China Y&X Beijing Technology Co., Ltd. Company Cases

一  Differentiated Design and Technology Selection for CIL and CIP Processes Although both CIL (carbon-in-leach) and CIP (carbon-in-pulp) processes are activated carbon adsorption gold extraction processes, they differ significantly in process design, operational logic, and applicable scenarios:  Differentiating Mechanisms: CIL simultaneously reduces the liquid gold concentration through leaching and adsorption, driving the cyanidation reaction kinetics. CIP optimizes leaching and adsorption conditions step by step to reduce impurity interference, but the process is more complex. 二  Key Influences of Activated Carbon Adsorption Kinetics on Gold Recovery The adsorption efficiency of activated carbon for gold-cyanide complex (Au(CN)₂⁻) is determined by both pore structure and chemical modification. The key parameters are as follows: 1. Adsorption Kinetic Model Diffusion-controlled Stage: Au(CN)₂⁻ migrates to adsorption sites through micropores (1000 m²/g). Chemical Adsorption Stage: Oxygen-containing functional groups (such as carboxyl and phenolic hydroxyl groups) on the activated carbon surface coordinate with Au(CN)₂⁻, with an apparent activation energy of 15-18 kJ/mol (laboratory measured values). 2. Optimized Parameters Pore Structure: Coconut shell charcoal with a micropore ratio >70% has a gold adsorption capacity of 6-8 kg Au/t charcoal; fruit shell charcoal with a micropore ratio 5 g/t), modified coconut shell charcoal with a K value ≥30 is recommended. The gold concentration in the tailings can be controlled at 0.05-0.1 mg/L. 三  Pretreatment Technology for Arsenic-Containing Gold Ore and Efficiency Improvement Mechanism Arsenic compounds (such as FeAsS) encapsulating gold particles is the primary cause of low leaching yields. Pretreatment technologies release gold through mineral dissociation: 1. Roasting Oxidation Method Process Parameters: Two-stage roasting (first stage at 650°C to remove arsenic and produce As₂O₃ gas, second stage at 800°C to remove sulfur and produce porous Fe₂O₃ roasted sand). Verification: After roasting a high-arsenic ore (12% As content), the gold leaching rate increased from 41% to 90.5%, but a flue gas purification system (As₂O₃ capture efficiency >99%) was required. 2. Pressurized Oxidation Method Acidic Oxidation: Under conditions of 190°C and 2.0 MPa, arsenopyrite decomposes into Fe₃⁺ and SO₄²⁻, converting arsenic into H₃AsO₃, increasing the gold leaching rate to 88%-95%. Limitations: Titanium reactors cost $30 million per 10,000 tons of production capacity, making them suitable only for large-scale mines. 3. Biooxidation Method Microbial Action: Acidithiobacillus ferrooxidans catalyzes the conversion of Fe²⁺ to Fe³⁺, dissolving the arsenopyrite coating and achieving an arsenic removal rate of >90%. Efficiency Improvement: Biooxidation of a difficult-to-treat gold ore (2.5 g/t Au, 8% As) increased the cyanide leaching rate from 25% to 92%, and the oxidation cycle was optimized to 7 days (with the addition of an Fe³⁺ catalyst). 四  Large-Scale Application and Technological Breakthroughs in Biooxidation Pretreatment Due to its environmental advantages, biooxidation technology has achieved commercial application in specific scenarios: 1. Applicable Limits Ore Type: Sulfide-encapsulated gold ore (As 1%-15%), mineral dissociation degree 99% (producing scorodite FeAsO₄·2H₂O). A large mine in Peru: Daily processing of 2,000 tons of ore containing 20% ​​arsenic, achieving a slag cyanide recovery rate >90%, and a 30% reduction in overall costs compared to roasting. 3. Technical Bottlenecks and Breakthroughs Bacterial Acclimation: Arsenic-tolerant strains (such as Leptospirillum ferriphilum) can survive at As₃⁺ concentrations of 15 g/L, increasing oxidation rates by 25%.  Process Coupling: The combined biooxidation + CIL process can process ultra-low-grade ores (Au 0.8 g/t), achieving an overall recovery rate exceeding 85%.

For every practitioner or student in the mineral processing field, a deep understanding and mastery of basic mineral processing methods is the golden key to unlocking the door to professional expertise. The separation of useful minerals from gangue minerals in ore is a critical step in the entire mineral resource development and utilization process. The purpose of mineral processing is to enrich useful minerals through various methods, remove harmful impurities, and provide qualified raw materials for subsequent smelting or industrial applications. This article systematically reviews and deeply analyzes five of the most basic and widely used mineral processing methods, aiming to help readers build a clear knowledge framework, ensuring a clear understanding of the principles and straightforward application. These five core methods are:       Gravity Separation       Flotation       Magnetic Separation       Electrostatic Separation       Chemical Processing (Hydrometallurgy) 01 Gravity Separation  Gravity separation (abbreviated as gravity separation) is one of the oldest mineral processing technologies, with its application dating back thousands of years to gold mining. Today, gravity separation remains important in the processing of tungsten, tin, gold, iron ore, and coal, due to its low cost, minimal environmental impact, and high processing capacity. Core Principle: Gravity separation is fundamentally based on the density differences between minerals. When mineral particles are in a moving medium (primarily water or air), they are subject to the combined effects of gravity, fluid dynamics, and other mechanical forces. High-density particles settle quickly and settle in the lower layers of the equipment, while low-density particles settle slowly and settle in the upper layers. Specific equipment and process flows can separate these two density groups. Particle size and shape also influence the separation process, so strict particle size control of the incoming material is often required in practice. Applicable conditions: There is a significant density difference between minerals, which is the prerequisite for the effective operation of gravity separation. It can handle a wide range of particle sizes and is particularly good at processing coarse-grained ores that are difficult to process with other methods.   It is suitable for processing gold and tin, wolframite, hematite and coal. Main equipment: Jig: It loosens the bed layer and separates it into layers according to density through periodic vertical alternating water flow. It is commonly used to process coarse and medium-sized ores and coal.  Shaking table: On an inclined bed, it utilizes the differential reciprocating motion of water flow and bed surface to loosen and separate the ore particles into layers and perform zonal separation. It is suitable for the separation of fine-grained ores. Spiral chute/spiral concentrator: It utilizes the combined effects of gravity, centrifugal force and water flow to separate the ore slurry as it flows in the spiral trough. It is suitable for processing fine-grained materials with a particle size of 0.03mm to 0.6mm.   Heavy medium separator: It uses a heavy suspension with a density between useful minerals and gangue as the separation medium. Ore particles with a density less than the medium float up, while those with a density greater than the medium sink, achieving precise separation. 02 Flotation Flotation is one of the most widely used mineral processing methods, particularly in the processing of non-ferrous metals (copper, lead, zinc), precious metals (gold, silver), and various non-metallic ores. Core Principles: Flotation exploits differences in the physical and chemical properties of mineral surfaces—namely, their varying floatability (hydrophobicity). By adding a series of specific flotation agents to a fully ground slurry, these surface properties can be artificially altered. 1. Regulators adjust the slurry's pH, among other factors, to create an optimal environment for other agents to function. 2. Collectors selectively adsorb onto the target mineral surface, rendering it hydrophobic (non-wettable by water). 3. Frothers reduce the surface tension of water, generating a large number of stable bubbles of optimal size. After treatment with the reagent, the hydrophobic target mineral particles selectively adhere to the bubbles and float to the surface of the slurry, forming a mineralized foam layer. The hydrophilic gangue minerals, on the other hand, remain in the slurry. The foam is scraped off with a scraper to obtain the enriched concentrate. Applicable conditions: Suitable for processing various sulfide ores with fine particle size and complex composition, such as copper, lead, zinc, nickel, molybdenum and other ores.  Widely used in the separation of oxide ores, non-metallic ores (such as fluorite, apatite) and precious metal ores. Flotation is an extremely effective method for separating minerals with similar density and no obvious difference in magnetic and electrical properties. Key elements (reagent system): The effectiveness of flotation depends heavily on the correct reagent system, including reagent type, dosage, order of addition, and location. Collectors: These agents, such as xanthates and nitroglycerins, are key to achieving hydrophobicity.  Frothers: These agents, such as pine oil (No. 2 oil), are responsible for creating stable foam.  Adjusters: These agents include activators (such as copper sulfate), inhibitors (such as lime and cyanide), and pH adjusters, used to enhance or diminish the floatability of minerals and improve separation selectivity. 03 Magnetic Separation Magnetic separation is a physical method that uses the magnetic difference of minerals for sorting. The process is simple and usually does not cause environmental pollution. It plays an indispensable role in the selection of ferrous metal ores (especially iron ore). It is also widely used to remove iron-containing impurities or recover magnetic substances from other minerals. Core principle: When ore particles pass through the uneven magnetic field generated by the magnetic separator, ore particles with different magnetic properties will be subject to magnetic forces of different magnitudes.  Strongly magnetic minerals (such as magnetite) will be attracted by the strong magnetic force and adsorbed to the surface of the magnetic pole (such as the magnetic drum). With the movement of the magnetic pole, they are taken to the designated position, leave the magnetic field and fall to become concentrates.  Non-magnetic or weakly magnetic minerals (such as quartz and some gangue) are subject to little or almost no magnetic force. Under the action of gravity and centrifugal force, they move along the original path and become tailings. Applicable conditions: Magnetite sorting: Magnetic separation is the most important and efficient method for processing magnetite. Sorting other magnetic minerals: It can also be used to sort manganese ore, chromite, ilmenite and some rare metal minerals with weak magnetism (such as wolframite). Iron removal: In the purification of non-metallic mineral raw materials such as ceramics and glass, it is used to remove harmful iron impurities to improve the whiteness of the product. Heavy medium recovery: In heavy medium coal or ore dressing, it is used to recover magnetic heavy materials such as magnetite powder. Main equipment: There are many types of magnetic separators. According to the magnetic field strength, they can be divided into weak magnetic field, medium magnetic field and strong magnetic field magnetic separators; according to the equipment structure, they can be divided into drum type, roller type, disc type and magnetic separation column type. Permanent magnet drum magnetic separator: The most widely used, often used to process strongly magnetic magnetite, and divided into co-current, counter-current and semi-counter-current types according to the slurry flow direction.  High gradient magnetic separator: It can generate a strong magnetic field gradient, which is used to sort weakly magnetic minerals or remove fine-grained iron impurities. • Magnetic pulley/magnetic drum: Commonly used for dry pre-selection to remove large iron pieces before the material enters the crusher to protect the equipment. 04 Electric separation Electrostatic separation utilizes differences in the conductive properties of minerals to separate them in a high-voltage electric field. This dry separation method is particularly suitable for water-scarce areas. While not as widely used as the previous three methods, it plays an irreplaceable role in separating certain mineral combinations, such as scheelite from cassiterite and zircon from rutile.  Core Principle: The electrostatic separation process primarily involves two steps: charging and separation.When preheated and dried mineral particles enter the high-voltage electric field formed by corona electrodes and rotating rollers:  Conductive minerals (such as ilmenite and cassiterite) quickly acquire an electric charge and rapidly dissipate it due to contact with the grounded rollers. After losing their charge, they are thrown from the rollers by centrifugal force and gravity.  Non-conductive minerals (such as zircon and quartz) have poor conductivity and are difficult to dissipate after acquiring an electric charge. They are attracted to the roller surface by electrostatic forces, moving to the rear of the roller as the roller rotates, and then being swept away by brushes.Since the two minerals have significantly different motion paths, separation is achieved.  Applicable Conditions: There must be significant differences in electrical conductivity between minerals. Common conductive minerals include magnetite, ilmenite, cassiterite, etc.; non-conductive minerals include quartz, zircon, feldspar, scheelite, etc.  Commonly used in the selection of non-ferrous metals, ferrous metals and rare metal ores, especially for separating associated minerals from mixed concentrates of gravity separation or magnetic separation.  The materials to be selected must be strictly dry, clean and of uniform particle size.  Main equipment:  Roller electrostatic separator: It is the most commonly used electrostatic separation equipment, which consists of a rotating grounded roller and a high-voltage corona electrode to form a working area. Plate/screen plate electrostatic separator: It is used to process materials with different particle size ranges. 05 Chemical Ore Dressing / Hydrometallurgy Chemical ore dressing, often closely associated with the concept of hydrometallurgy, utilizes chemical reactions to alter the physical phases of mineral components, thereby separating useful components from impurities. This method is particularly suitable for processing low-grade, complex, and finely impregnated ores, such as copper oxide, gold, and uranium ores, which are difficult to separate using traditional physical separation methods.  Core Principle:  Its core is selective leaching. Using a specific chemical solvent (leachant), under specific temperature and pressure conditions, the target metal or its compounds in the ore are selectively dissolved into a solution, while the gangue minerals remain in the solid phase (leaching residue). The main steps include:       1. Leaching: The ore is treated with a leaching agent such as an acid (such as sulfuric acid), an alkali (such as sodium hydroxide), or a salt solution (such as cyanide) to release the useful metal into the liquid phase.        2. Liquid-Solid Separation: The target metal-rich solution (leachate) is separated from the leaching residue.       3. Solution purification and enrichment: Use precipitation, solvent extraction or ion exchange to remove impurity ions in the solution and increase the concentration of the target metal.       4. Metal recovery: Extract the final metal product or its compound from the purified solution through electrolysis, displacement or precipitation. Applicable conditions: Processing of low-grade oxide ores: For example, the acid leaching-extraction-electrolysis process for low-grade copper oxide ores.  Extraction of precious metals: For example, the cyanide leaching method for gold ores is the most widely used gold extraction process.  Processing of complex and difficult-to-separate ores: For ores with similar physical properties and complex interbedded relationships, chemical beneficiation is often the only effective way.  Metal recovery from waste: It has broad prospects in areas such as battery recycling and electronic waste treatment.  Typical processes: Cyanide gold extraction: Use sodium cyanide solution to dissolve the gold in the ore, and then replace the gold with zinc powder. Acid leaching of copper: Leach the copper oxide ore with dilute sulfuric acid to obtain a copper sulfate solution, which is then extracted and electrolyzed to obtain high-purity cathode copper.   Bayer process for producing alumina: Treating bauxite with sodium hydroxide solution under heated and pressurized conditions is a classic hydrometallurgical process for producing alumina. The five fundamental methods of mineral separation—gravity separation, flotation, magnetic separation, electrostatic separation, and chemical separation—form the cornerstone of modern mineral processing technology. Each method has its own unique scientific principles and scope of application. In actual production, mineral processing engineers often need to flexibly select a single method or combine multiple methods based on the specific properties of the ore (such as mineral composition, dissemination characteristics, and physical and chemical properties), technical and economic indicators, and environmental protection requirements to develop the optimal mineral processing process, thereby achieving efficient, economical, and green development of mineral resources. A deep understanding and mastery of these fundamental principles is fundamental for every mineral processing engineer to solve practical problems and promote technological innovation.

Flotation, one of the most widely used and core separation technologies in the modern mineral processing industry, relies heavily on the efficient mixing and interaction of the gas, liquid, and solid phases within the flotation cell. A flotation cell is more than just a simple container; it's a complex multiphase flow reactor whose core mission is to create optimal fluid dynamics for the encounter, collision, adhesion, and mineralization of hydrophobic mineral particles and bubbles. This article will delve into the two key operations of flotation cells: aeration and agitation. It will systematically explain how these two synergistic effects achieve "perfect mixing" of the gas, liquid, and solid phases, ensuring efficient and accurate mineral separation. 一 The core of the flotation process: the essence and goal of three-phase mixing The essence of the flotation process is the introduction of air (gas phase) into the ore slurry (a liquid-solid two-phase system). Through physical and chemical reactions, target mineral particles selectively attach to air bubbles, forming mineralized bubbles. These bubbles rise to the surface of the slurry as a froth layer that is scraped off, while gangue minerals remain in the slurry and are discharged as tailings. The success of this process depends directly on the following three conditions: 1 Effective suspension of solid particles: Adequate agitation must ensure that ore particles of varying sizes and densities are uniformly suspended in the slurry, preventing coarse and heavy particles from settling and ensuring that all particles have the opportunity to come into contact with the bubbles. 2 Effective gas dispersion: The introduced air must be sheared and broken into a large number of tiny, appropriately sized bubbles, which are then evenly dispersed throughout the flotation cell to increase the gas-liquid interface and the probability of collision between bubbles and ore particles. 3 A controllable hydrodynamic environment: The flotation cell must maintain sufficient turbulence to promote particle suspension and bubble dispersion, while avoiding excessive turbulence that could cause the dislodgment of attached ore particles. It is necessary to construct a flow field in the trough that has both a high turbulent kinetic energy dissipation zone (to promote collision) and a relatively stable zone (to facilitate the floating of mineralized bubbles). Therefore, "perfect mixing" is not a simple homogenization, but refers to the uniform distribution of the three phases at the macro level and the creation of controlled turbulence and flow field structures that are conducive to the selective adhesion of particles and bubbles at the micro level. 二 Mechanically Agitated Flotation Cells: A Classic Fusion of Aeration and Agitation. Mechanically agitated flotation cells are currently the most widely used flotation equipment. Their core component, the impeller-stator system, organically combines the two functions of aeration and agitation.  1. Agitation: The impeller's pumping and vortexing impellers, driven by a motor, rotate at high speed, functioning like a pump, primarily achieving the following agitation effects: Slurry Circulation and Suspension: The impeller's rotation generates a powerful centrifugal force, drawing slurry from the center and ejecting it radially or axially. This pumping action creates a complex circulating flow within the cell, ensuring the slurry remains in motion. This ensures that dense and large particles are effectively agitated and kept suspended. Turbulence Generation: The high-speed rotation of the impeller creates a sharp velocity gradient and intense turbulence in the surrounding area (particularly at the blade tips). This highly turbulent zone is the primary site for bubble breakage and particle-bubble collisions.  2. Aeration: Self-aspiration and Forced Aeration. Mechanically agitated flotation cells are primarily categorized by the aeration method: self-aspiration and forced aeration (or aeration-agitation). Self-aspirating flotation machines (such as the SF model) :feature a cleverly designed impeller that creates a negative pressure zone within the impeller chamber as it rotates. Air is automatically drawn in through the suction pipe and mixed with the slurry within the impeller chamber. This type of flotation machine offers a simple structure and requires no external blower. Forced air supply flotation machine (such as KYF type): Through an external low-pressure blower, compressed air is forced into the impeller area through the hollow impeller main shaft or independent pipes. This method can accurately control the amount of air, is not affected by the impeller speed and slurry level, and has a stronger adaptability to process conditions, especially suitable for large flotation machines. 3. "Impeller-stator" synergistic effect The stator is a stationary component installed around the impeller, usually with guide vanes or openings. Its synergy with the impeller is crucial to achieving "perfect mixing": Flow stabilization and guidance: The slurry-air mixed flow thrown out from the impeller at high speed has a strong tangential velocity component, which can easily form huge vortices in the tank, causing liquid surface instability and affecting the stability of the foam layer. The guide vanes of the stator can effectively convert this tangential flow into a radial flow that is more conducive to the dispersion of bubbles and particles. Promote bubble dispersion: Through the flow stabilization effect of the stator, bubbles can be more evenly distributed throughout the effective volume of the flotation tank, rather than concentrated in certain areas. Isolate turbulence: The stator acts as an "energy barrier", separating the high turbulence area near the impeller from the separation area and foam area at the top of the tank, creating a relatively quiet and stable environment for the stable floating and enrichment of mineralized bubbles. The high-speed rotation of the impeller achieves slurry suspension and gas absorption/crushing. The stator then stabilizes and guides the flow, creating three functionally distinct fluid dynamic zones within the tank: a highly turbulent mixing zone (near the impeller), a relatively stable separation zone (in the middle of the tank), and a largely static froth zone (on the surface of the slurry). This achieves efficient mixing and orderly separation of gas, liquid, and solid phases. 三 Flotation Column: Another Intelligent Way to Achieve Three-Phase Mixing. Unlike the violently turbulent environment of mechanically agitated flotation cells, flotation columns represent an alternative design philosophy, achieving three-phase mixing through countercurrent contact in a relatively static environment. The aeration core—the bubble generator: Flotation columns lack mechanical agitators. Their aeration and mixing functions rely primarily on a bubble generator located at the bottom. The bubble generator uses pressurized air, utilizing microporous media, jet flow, or the Venturi effect, to generate a large number of fine bubbles within the slurry. These microbubbles are key to the flotation column's efficient capture of fine minerals. Countercurrent contact mechanism: The slurry is fed from the upper center of the flotation column and flows slowly downward, while fine bubbles are generated from the bottom and rise slowly upward. This countercurrent contact mechanism provides a longer interaction time and a higher probability of collision between particles and bubbles. Low-turbulence environment: The flotation column lacks high-speed rotating components, maintaining a low-turbulence, laminar or near-laminar flow. This "quiet" environment significantly reduces the shedding of adhered mineral particles, greatly facilitating the recovery of fine and fragile minerals. Washing water system: A washing water device is installed on the top of the flotation column to effectively wash away the gangue particles entrained in the foam layer, thereby obtaining a higher grade concentrate. The flotation column, through its unique bubble generation technology and countercurrent contact method, achieves effective contact and separation of gas, liquid and solid phases in a more "gentle" way, showing excellent performance especially when processing fine-grained materials. 四 Technology Development and Optimization Direction  In order to pursue a more perfect "three-phase mixing", the aeration and stirring technology of the flotation tank is still being improved: Large-scale and flow field optimization: With increasing processing capacity, the volume of flotation cells is increasing. Currently, ultra-large flotation machines with a capacity of hundreds of cubic meters are in operation. This places higher demands on the design of the impeller-stator structure and flow field control. Numerical simulation technologies such as computational fluid dynamics (CFD) are widely used to guide equipment optimization design to ensure uniform particle suspension and gas dispersion within the huge cell. New impellers and stators: The development of various new impellers (such as backward-inclined blades and multi-stage impellers) and stators aims to achieve greater slurry pumping capacity and more ideal bubble dispersion with lower energy consumption.  Intelligent control: By installing various sensors to monitor parameters such as slurry level, foam layer thickness, and aeration in real time, and combining machine vision and artificial intelligence technologies to analyze foam status, automatic optimization control of agitation intensity and aeration volume is achieved. This is a key direction for improving flotation efficiency and moving towards intelligent mineral processing.

In the modern mineral processing industry, flotation is one of the most widely used and effective methods. Its core principle is to exploit the differences in the physical and chemical properties of mineral surfaces. By adding flotation reagents, the target mineral's hydrophobicity is selectively altered, causing it to adhere to bubbles and float upward, thereby separating it from the gangue minerals. An optimized reagent system is crucial for successful flotation, directly determining the concentrate grade and recovery rate, and thus impacting the economic efficiency of the entire mineral processing plant. However, faced with increasingly complex, lean, fine, and mixed ore resources, traditional trial-and-error methods are no longer sufficient to efficiently and accurately select the optimal reagent combination. This article aims to systematically explore how to scientifically and efficiently select the optimal flotation reagent combination for mineral processing professionals. 一 The Basics of Flotation Reagent Systems: Understanding the Components and Their Synergistic Effects A complete flotation reagent system usually consists of three categories: collectors, frothers and regulators. Each type of reagent has its own function and affects each other, forming complex synergistic or antagonistic effects. Collectors:the core of the flotation process. Their molecules contain both polar and non-polar groups. They selectively adsorb to the surface of the target mineral, rendering it hydrophobic through their non-polar groups. The choice of collector is primarily based on the properties of the mineral. For example, xanthate and nitrophenol are commonly used for sulfide ores, while fatty acids and amines are often used for non-sulfide ores. Frothers: Their primary function is to reduce the surface tension of water, producing a stable, appropriately sized foam that acts as a carrier for hydrophobicized mineral particles. An ideal frother should produce a foam with a certain degree of brittleness and viscosity, effectively capturing mineral particles while also easily breaking up after the concentrate is scraped off, facilitating subsequent processing. Adjusters: These are the most diverse and complex type of agent within the flotation system. They are primarily used to adjust the slurry environment and mineral.surface properties to enhance separation selectivity. They primarily include:       Depressants: Used to reduce or eliminate the floatability of certain minerals (usually gangue minerals or certain easily floatable sulfide ores). For example, lime is used to depress pyrite, and water glass is used to depress silicate gangue minerals.       Activators: Used to enhance the floatability of certain difficult-to-float or depressed minerals. For example, copper sulfate is often added to activate oxidized sphalerite during flotation.       pH Adjusters: Adjust the pH of the slurry to control the effective form of the collector, the surface electrical properties of the mineral, and the conditions under which other agents react. Commonly used agents include lime, soda ash, and sulfuric acid.       Dispersants: Used to prevent sludge capping or selective flocculation and improve the dispersion of ore particles, such as water glass and sodium hexametaphosphate. Synergy is key to developing an efficient reagent system. For example, mixing different types of collectors (such as xanthate and black powder) often exhibits enhanced capture capacity and selectivity compared to single agents. The clever combination of inhibitors and collectors can achieve preferential flotation or mixed flotation of complex polymetallic ores. Understanding the individual functions and interaction mechanisms of these reagents is the first step in systematic screening. 二 Systematic Screening Methodology: From Experience to Science Systematic screening of reagent combinations aims to replace traditional single-factor or "cook-and-dish" experiments with scientific experimental design and data analysis, thereby identifying the optimal or near-optimal reagent combination in a shorter time and at a lower cost. Currently, mainstream methods include single-factor conditional experiments, orthogonal experimental design, and response surface methodology. 1. Single-factor conditional experiment This is the most basic experimental method. It involves keeping all other conditions fixed and varying the dosage of a single reagent. The effect on flotation performance indicators (grade, recovery) is observed across a series of experimental points. This method is simple and intuitive, and is essential for initially determining the approximate effective dosage range for various reagents. However, its major drawback is that it cannot examine interactions between reagents and makes it difficult to identify the global optimum. 2. Orthogonal experimental design When multiple factors (multiple reagents) need to be investigated and their optimal combination needs to be identified, orthogonal experiments are an efficient and cost-effective scientific method. They utilize an "orthogonal table" to arrange experiments. By selecting a few representative experimental points, the primary and secondary relationships among the factors and the optimal level combination can be scientifically analyzed. Implementation Steps: 1. Determine Factors and Levels: Identify the reagent types (factors) to be investigated and set several different dosages (levels) for each reagent. 2. Select an Orthogonal Array: Based on the number of factors and levels, select an appropriate orthogonal array to arrange the experimental plan. 3. Conduct Experiments and Data Analysis: Conduct flotation tests using the combinations arranged in the orthogonal array, recording concentrate grade and recovery. Using range analysis or variance analysis, the significance of each factor's impact on the performance indicators can be determined, and the optimal reagent dosage combination can be determined. The advantage of orthogonal experiments is that they significantly reduce the number of experiments and effectively evaluate the independent impact of each factor. They are one of the most widely used optimization methods in industrial testing. 3. Response Surface Methodology The response surface methodology is a more sophisticated optimization method that combines mathematical and statistical techniques. It not only finds the optimal combination of conditions but also establishes a quantitative mathematical model that relates flotation performance indicators to reagent dosages. Implementation Steps: 1. Preliminary Experiments and Factor Screening: Single-factor experiments or Praskett-Berman designs are used to quickly identify key reagents with significant impacts on flotation performance. 2. Steepest Ramp Experiment: Within the initial region of significant factors, experiments are conducted along the direction of the fastest response change (gradient direction) to quickly approach the optimal region. 3. Central Composite Design: After the optimal region is determined, experiments are arranged using a central composite design. This design effectively estimates a second-order response surface model, including linear, square, and interaction terms for reagent dosage. 4. Model Development and Optimization: Through regression analysis of experimental data, a second-order polynomial equation is established, linking the response (e.g., recovery) to the dosage of each reagent. This model can be used to generate three-dimensional response surface plots and contour plots, visually demonstrating reagent interactions and accurately predicting the optimal reagent dosage for the highest grade or recovery. Response surface methodology can reveal interactions between factors and accurately predict optimal operating points, making it ideal for fine-tuning pharmaceutical formulations. 三 From the Laboratory to Industrial Application: A Complete Screening Process A successful pharmaceutical system development needs to go through a complete process from small-scale laboratory trials to industrial production verification. 1. Ore Property Research: This is the foundation of all work. Through chemical analysis, phase analysis, and process mineralogy, a comprehensive understanding of the ore's chemical composition, mineralogy, embedded particle size, and the interplay between useful and gangue minerals is essential to provide a basis for preliminary reagent selection. 2. Laboratory Pilot Test (Beaker Test): Conducted in a 1.5-liter or smaller flotation cell. The objectives of this stage are:       Using single-factor experiments, preliminarily screen effective collector, depressant, and frother types and determine their approximate dosage ranges.       Using orthogonal experiments or response surface methodology, optimize the combination of several selected key reagents to determine the optimal reagent system under laboratory conditions. 3. Laboratory Closed-Circuit Test (Expanded Continuous Test): Simulating the middling ore recycling process in industrial production, conducted in a slightly larger flotation cell (e.g., 10-30 liters). This stage verifies and refines the reagent system developed in the pilot test and examines the impact of middling ore return on the stability of the entire flotation process and final performance. 4. Pilot (Semi-industrial) Testing: A small-scale, complete production system is established and operated continuously at the production site. The pilot test bridges laboratory research with industrial production, and its results directly impact the success and economic viability of the final industrial application. During this stage, the reagent system undergoes final testing and adjustments. 5. Industrial Application: The reagent system and process flow established in the pilot test are applied to large-scale production, with continuous fine-tuning and optimization based on fluctuations in ore properties during production. 四 Future Trends: Intelligence and New Agent Development With technological advancements, the screening and application of flotation agents are moving towards smarter and more efficient approaches. Computational Chemistry and Molecular Design: Quantum chemical calculations and molecular simulation techniques can be used to study the interaction mechanisms between agents and mineral surfaces at the molecular level and predict agent performance, enabling targeted design and synthesis of new, highly efficient flotation agents, significantly shortening the R&D cycle. High-Throughput Screening and Artificial Intelligence: Drawing on the principles of new drug development, combined with automated experimental platforms and high-throughput computing, large numbers of agent combinations can be rapidly screened. Simultaneously, artificial intelligence and machine learning technologies are also beginning to be applied to flotation processes. By analyzing historical production data and establishing predictive models, they enable real-time intelligent control and optimization of agent dosage. Environmentally Friendly New Agents: With increasingly stringent environmental regulations, the development of low-toxic, biodegradable, and environmentally friendly flotation agents has become a key development direction. Systematically screening for the optimal flotation agent combination is a complex undertaking involving multiple disciplines. This requires mineral processing technicians to not only have a deep understanding of the basic principles of flotation chemistry and the synergistic effects of reagents, but also to master scientific experimental design methods such as orthogonal experiments and response surface methodology. By following the rigorous process of "ore property research - laboratory testing - closed-circuit testing - pilot testing - industrial application" and actively embracing new technologies such as computational chemistry and artificial intelligence, we can more scientifically and efficiently address the challenges posed by complex and difficult-to-process ores, providing solid technical support for the clean and efficient utilization of mineral resources.

In the mining industry, a widely held adage is, "No two ores are exactly alike." This isn't just a simple rule of thumb; it's a core technical principle that governs the entire mineral resource development process. It profoundly reveals the natural heterogeneity of ores and directly determines the complexity and uniqueness of mineral processing process design—there's no "one-size-fits-all" process suitable for all ores. This article will delve into the root causes of ore heterogeneity and the inevitable requirements for customized mineral processing process design, aiming to provide mining professionals with a comprehensive, accurate, and insightful perspective.   Ore "Personality": The Root of Heterogeneity   Ore heterogeneity stems from the long and complex geological process of mineralization. Different geological tectonic environments, mineralization temperatures and pressures, and the physical and chemical conditions of the medium all contribute to the diverse nature of ores. Even within the same ore body, different sections, or even two adjacent ores, significant differences in composition and structure can exist. This "individuality" is primarily manifested in the following aspects:   Complexity of chemical and mineralogical composition: In addition to valuable metals or minerals, ores also contain coexisting or associated gangue and other metallic minerals. The types, contents, and occurrence states of these components (e.g., as independent minerals or isomorphously present within the crystal lattice of other minerals) vary greatly. For example, in some iron ores, iron may exist in various forms, such as strongly magnetic magnetite, weakly magnetic hematite, or limonite, accompanied by minerals such as pyroxene and mica. This poses significant challenges to single-source separation methods.   Variation in physical properties: Ores also vary in physical properties such as hardness, density, magnetic properties, electrical properties, grindability, mud content, and water content. Variations in ore hardness and grindability directly impact the selection of crushing and grinding equipment, energy consumption, and ultimately, grinding efficiency.   Diversity of Structural Structures: The distribution of minerals within an ore, specifically the intergrowth between useful and gangue minerals, and the size and shape of the embedded particles, are key factors influencing the difficulty of mineral processing. The finer the particle size of the useful minerals, the finer the ore grinding is required to separate the individual components, which undoubtedly increases the processing cost.   Customized Process Flow: An Inevitable Choice for Tailoring to the Ore   Precisely because of ore heterogeneity, the design of mineral processing flows must move away from a one-size-fits-all approach and toward customized, tailored processing. Developing a process flow is the primary and core task of mineral processing plant design. Its fundamental design principle is based on detailed mineral processing test research and reference to proven experience from similar mines.   Mineral Processing Tests: The Cornerstone of Process Design   Comprehensive mineral processing tests must be conducted before any mineral processing plant design. Systematic testing provides a deep understanding of the ore's selectivity, including:   Determining the Optimal Grinding Fineness: Grinding is designed to fully separate useful minerals from gangue minerals. Insufficient grinding fineness can result in the loss of recovery of some useful minerals, while overgrinding wastes energy and may generate slime, interfering with subsequent flotation operations.   Choosing the most effective separation method: The appropriate separation method is selected based on the differences in the physical and chemical properties of the different minerals in the ore. For example, magnetic separation can be used for magnetite; flotation is often used for copper sulfide ores; and gravity separation is the primary method for placer gold ores. In many cases, a combination of multiple methods is required to achieve efficient separation.   Optimizing the reagent system and process parameters: In chemical separation methods such as flotation, the type of reagent, dosage, duration of action, and pH of the slurry all have a crucial impact on separation performance. Even when processing the same graphite ore, the required reagent dosage and grinding method may vary significantly due to differences in crystallinity and flake size.   Flexibility and Optimization in Process Design   An excellent mineral processing process must not only be technically feasible and economically sound, but also possess a degree of flexibility to adapt to changes in ore properties that may occur during a mine's production process. For example, changes in the type of ore being processed may necessitate adjustments to the grinding fineness or flotation process. Furthermore, with technological advancements and the pursuit of cost reduction and efficiency, mineral processing process optimization is an ongoing process. Introducing more efficient crushing and grinding equipment and adopting automated control technologies can help improve mineral processing efficiency and reduce operating costs.   The Dangers of a "One-Size-Fits-All" Approach: Double Loss of Economy and Resources   Ignoring the specific characteristics of the ore and forcibly adopting a so-called "one-size-fits-all" or standardized process can have serious consequences. Fluctuations in ore quality indicators, such as grade, particle size, and intercalation characteristics, can directly lead to deterioration in production performance if the mineral processing process cannot adapt. Research has shown that an inappropriate process can lead to:   Reduced mineral processing recovery: Large amounts of valuable metals are lost in tailings due to ineffective separation or separation, resulting in a significant waste of resources.   Decreased concentrate grade: Excessive gangue minerals or harmful impurities in the concentrate affect the efficiency of subsequent smelting processes and the quality of the final product, reducing the product's market competitiveness.   Soaring production costs: To compensate for process defects, increased reagent consumption and energy consumption may be required, leading to a significant increase in production costs.

Gold Recovery from E-Waste Using Eco-Friendly Extraction Reagents I. Pretreatment Steps 1.1 Crushing and Screening Purpose: Increase surface area to facilitate subsequent gold leaching. Operations: ① Use a crusher to break down e-waste (e.g., circuit boards, CPUs, gold fingers) into 0.5–1 mm particles. ② Screen the material to remove oversized or undersized particles, ensuring uniform particle size. ③ Employ magnetic separation to remove ferromagnetic impurities (e.g., iron, nickel). ④ Rinse the crushed material with clean water to eliminate dust and impurities, then air-dry for further use.   1.2 Roasting Treatment (Optional) Purpose: Remove organic materials and break the bonding between metals and plastics. Operations: ① Place the crushed e-waste in a roasting furnace and roast at 500–600°C for 1–2 hours. ② Ensure proper ventilation during roasting to prevent the accumulation of harmful gases. ③ After roasting, allow the waste to cool to room temperature, then perform secondary crushing until the particle size is less than 0.5 mm.   II. Preparation of Eco-Friendly Gold Extraction Agent YX500 Solution 2.1 Preparation of Eco-Friendly Gold Extraction Agent YX500 Solution Reagent: Eco-friendly gold extraction agent YX500. Concentration: Prepare a YX500 solution with a concentration of 0.05%–0.1% (i.e., 0.5–1 g/L). Method: ① Add an appropriate amount of clean water into the mixing tank. ② Slowly add the eco-friendly gold extraction agent YX500 in proportion while continuously stirring until it is completely dissolved. ③ Dosing time: Ensure the operation is completed within 10–20 minutes.   2.2 Alkalinity Adjustment Purpose: Prevent hydrogen cyanide gas volatilization and ensure smooth leaching reaction. Operations: ① Add sodium hydroxide (NaOH) or lime milk to adjust the solution pH to 10–11. ② Use pH test strips or a pH meter to verify the solution's alkalinity reaches the appropriate level.   III. Leaching Process 3.1 Leaching Equipment Equipment: Tower leaching tank or mechanically agitated tank. Temperature: Ambient temperature (20–25°C). If leaching acceleration is required, temperature may be increased to 40–50°C.   3.2 Reagent Addition & Reaction Conditions Dosing sequence: ① First, add sodium hydroxide (NaOH) solution for pH adjustment. ② Then, add the pre-prepared eco-friendly gold extraction agent YX500 solution and start the stirring device. ③ Dosing time: Must be completed within 10–20 minutes. Stirring speed: 200–300 rpm to ensure full contact between materials and solution.   3.3 Leaching Time & Oxidant Usage Leaching time: At ambient temperature: 24–48 hours. At 40–50°C: Can be reduced to 12–24 hours. Oxidant: ① To accelerate gold dissolution, hydrogen peroxide (H₂O₂, 0.1–0.5%) may be added or air may be introduced. ② Addition timing: Synchronized with the YX500 solution dosing and maintained continuously.   IV. Solid-Liquid Separation Filtration and Washing Method: Vacuum filtration or centrifugal separation equipment shall be employed. Operations: ① Filter the leached slurry to separate the gold-bearing solution (pregnant solution) from the residue. ② Wash the residue with dilute alkaline solution (pH 10-11) to recover residual gold elements.   V. Gold Recovery Methods Method 1: Zinc Powder Replacement Process Steps: ① Slowly add zinc powder to the pregnant solution at a ratio of 5-10 g/L. ② Maintain continuous stirring with a reaction time of 2-4 hours. ③ Filter to obtain gold mud.   Method 2: Electrolysis Process Equipment: Stainless steel cathode, graphite or lead anode. Conditions: ① Current density: 1-2 A/dm², Voltage: 2-3 V. ② Electrolysis duration: 6-12 hours. Operations: ① After energizing the electrolytic cell, gold gradually deposits on the cathode. ② Remove the cathode and scrape off the deposited gold mud.   VI. Gold Mud Treatment and Refinement Acid Washing and Smelting Steps: ① Use dilute nitric acid or aqua regia to dissolve impurities, followed by filtration to obtain purified gold mud. ② Place the gold mud in a high-temperature electric furnace for smelting, then cast into gold ingots. Purity: Can reach ≥99.9%.   VII. Waste Liquid Treatment and Environmental Protection Measures Compliant Discharge Testing: Verify cyanide concentration to ensure it remains below 0.2 mg/L. Discharge: After meeting standards, release into wastewater treatment system.   VIII. Safety Precautions ① Ventilation: Maintain adequate ventilation in work areas to prevent hydrogen cyanide gas accumulation. ② Protection: Operators must wear gloves, masks, and protective goggles to ensure safety. ③ First Aid: Prepare amyl nitrite and other antidotes for emergency treatment of cyanide poisoning.       Detection of Cyanide Ion (CN¯) Concentration in Eco-Friendly Gold Extraction Reagents   Testing the cyanide ion (CN¯) concentration in eco-friendly gold extraction agents is a critical step to ensure their safety and effectiveness. The following outlines commonly used detection methods and their key operational points, categorized into two main types: laboratory testing methods and on-site rapid testing methods.   I. Laboratory Precision Detection Methods 1.1 Silver Nitrate Titration (Classical Method) Principle: Cyanide ions react with silver nitrate to form soluble [Ag(CN)₂]¯ complexes, with excess silver ions reacting with an indicator (e.g., silver chromate) to produce a color change. Steps: ① Dilute the sample and add sodium hydroxide (pH >11) to prevent hydrogen cyanide (HCN) volatilization. ② Use silver chromate as an indicator and titrate with standardized silver nitrate solution until the color changes from yellow to orange-red. Scope: Suitable for high cyanide concentrations (>1 mg/L); provides precise results but requires laboratory conditions.   1.2 Spectrophotometry (Isonicotinic Acid-Pyrazolone Method) Principle: In weakly acidic conditions, cyanide reacts with chloramine-T to form cyanogen chloride (CNCl), which then reacts with isonicotinic acid-pyrazolone to produce a colored compound. Quantification is achieved by measuring absorbance at 638 nm. Steps: ① Distill the sample if necessary to remove interferents. ② Add buffer and chromogenic reagents, then measure absorbance using a spectrophotometer. Calculate concentration via a standard curve. Advantage: High sensitivity (detection limit: 0.001 mg/L), ideal for trace-level analysis.   1.3 Ion-Selective Electrode (ISE) Method Principle: A cyanide electrode responds to CN¯ activity, measuring concentration via potential difference. Steps: ① Adjust sample pH to >12 with NaOH to avoid HCN interference. ② Calibrate the electrode, measure potential, and convert to concentration. Advantage: Rapid operation, broad detection range (0.1–1000 mg/L), but requires regular electrode calibration.   II. On-Site Rapid Detection Methods 2.1 Rapid Test Strips Principle: Strips contain chromogenic agents (e.g., picric acid) that change color (yellow to reddish-brown) upon reaction with cyanide ions. Procedure: Immerse the strip in the sample, then compare the color against a reference card for semi-quantitative reading. Features: Highly portable but relatively low accuracy; suitable for emergency screening.   2.2 Portable Cyanide Detectors Principle: Miniaturized spectrophotometric or electrode-based devices (e.g., Hach, Merck). Operation: Direct sample injection with automatic concentration display. Advantage: Combines speed and high precision, ideal for field use in mining areas.   2.3 Pyridine-Barbituric Acid Colorimetry (Simplified) Reagent Kit: Pre-packaged tubes with chromogenic agents; add water sample for colorimetric analysis. Detection Limit: ~0.02 mg/L, suitable for low-cyanide testing in eco-friendly gold extraction agents.   III. Precautions Safety Measures Cyanide is highly toxic! All testing must be conducted in a fume hood to prevent skin contact or inhalation. Waste liquid treatment: Oxidize with sodium hypochlorite (CN¯ + ClO¯ → CNO¯ + Cl¯). Interference Factors Sulfide (S²¯) and heavy metal ions may cause interference. Pre-distillation or masking agents (e.g., EDTA) should be used to eliminate their effects. Method Selection High-precision testing: Laboratory titration or spectrophotometry is preferred. Rapid screening: Test strips or portable devices are more practical.  

  Chapter 1: Characteristics of Lead-Zinc Ore Resources and Beneficiation   1.1 Global Resource Distribution Features Main Mineralization Types: Sedimentary Exhalative Deposits (55%) Mississippi Valley-Type Deposits (30%) Volcanogenic Massive Sulfide (VMS) Deposits (15%) Representative Deposits: China's Fankou Deposit (Proven reserves: Pb+Zn >5 million tonnes) Australia's Mount Isa Mine (Average zinc grade: 7.2%) Mineralogical Associations: Intimate PbS-ZnS intergrowth (Particle size distribution: 0.005-2mm) Precious metal associations (Ag content: 50-200g/t, often occurring as argentiferous galena)   1.2 Process Mineralogy Challenges Variable Iron Content in Sphalerite (Fe 2-15%): Impacts flotation behavior due to changes in surface chemistry, High-iron sphalerite (>8% Fe) requires stronger activation Secondary Copper Minerals (e.g., Covellite): Causes copper contamination in zinc concentrates (typically >0.8% Cu), Requires selective depression reagents (e.g., Zn(CN)₄²⁻ complexes) Slime Coating Effects: Becomes significant when -10μm particles exceed 15%, Mitigation methods: ---Dispersion agents (sodium silicate) ---Stage grinding-flotation circuits       Chapter 2: Modern Beneficiation Process Systems 2.1 Standard Selective Flotation Process Grinding and Classification Control ---Primary Closed-Circuit Grinding: Hydrocyclone classification, Circulating load: 120-150% ---Target Fineness: 65-75% passing 74μm, Galena liberation degree: >90% Lead Flotation Circuit ---Reagent Scheme: Reagent Type Dosage (g/t) Mechanism of Action Lime 2000-4000 pH adjustment to 9.5-10.5 Diethyl dithiocarbamate (DTC) 30-50 Selective galena collector MIBC (frother) 15-20 Froth stability control ---Equipment Configuration: JJF-8 Flotation Cells: 4 cells for roughing + 3 cells for cleaning Zinc Activation Control ---CuSO₄ Dosage: 250±50 g/t, Optimized with mixing intensity (power density: 2.5 kW/m³) ---Potential (Eh) Control Range: +150 to +250 mV   2.2 Innovative Bulk Flotation Technology Key Technological Breakthroughs: ---High-efficiency composite collector (AP845 + ammonium dibutyl dithiophosphate, 1:3 ratio) ---Selective depression removal technology (pH adjustment to 7.5±0.5 using Na₂CO₃) Industrial Application Cases: ---Throughput increased by 22% (reaching 4,500 t/d) at an Inner Mongolia mine ---Zinc concentrate grade improved by 3.2 percentage points   2.3 Dense Media Separation-Flotation Combined Process Pre-concentration Subsystem: ---Medium density control (magnetite powder D50=45μm) ---Three-product cyclone (DSM-800 type) separation efficiency Ep=0.03 Economic Analysis: ---When waste rejection rate reaches 35-40%, grinding costs are reduced by 28-32%       Chapter 3: Lead-Zinc Ore Beneficiation Reagents 3.1 Collector Types & Applications (1) Anionic Collectors Reagent Target Mineral Dosage (g/t) pH Range Notable Features Xanthates (e.g., SIPX) ZnS 50-150 7-11 Cost-effective, requires CuSO₄ activation Dithiophosphates (DTP) PbS 20-60 9-11 High Pb selectivity over Zn Fatty acids Oxidized ores 300-800 8-10 Needs dispersants (e.g., Na₂SiO₃) (2) Cationic Collectors Amines (e.g., Dodecylamine): Used in reverse flotation for silicate removal, Dosage: 100-300 g/t, pH 6-8 (3) Amphoteric Collectors Amino-carboxylic acids: Selective for Zn in complex ores, Effective at pH 4-6 (Eh = +200 mV)   3.2 Depressants & Modifiers Reagent Function Dosage (kg/t) Target Impurities Na₂S Zn depression in Pb circuit 0.5-2.0 FeS₂, ZnS ZnSO₄ + CN⁻ Pyrite depression 0.3-1.5 FeS₂ Starch Silicate depression 0.2-0.8 SiO₂ Na₂CO₃ pH modifier (buffer at 9-10) 1.0-3.0 -   3.3 Composite Reagents for Lead-Zinc Ore Beneficiation Composite beneficiation reagents refer to multifunctional reagent systems formed by integrating two or more functional components (collectors, depressants, frothers, etc.) through physical blending or chemical synthesis. Based on their composition, they can be classified into: (1) Physically Blended Type Mechanical mixing of individual reagents (e.g., diethyldithiocarbamate (DTC) + butyl xanthate at a 1:2 ratio) Typical example: LP-01 composite collector (xanthate + thiocarbamate) (2) Chemically Modified Type Molecularly engineered multifunctional reagents Typical examples: Hydroxamic acid-thiol complexes (dual collector-depressant functionality) Zwitterionic polymer depressants       Chapter 4: Key Equipment and Technical Parameters 4.1 Flotation Equipment Selection Guide Roughing Stage: KYF-50 flotation machine (aeration rate: 1.8 m³/m²·min) Cleaning Stage: Flotation column (Jameson Cell, bubble diameter: 0.8-1.2 mm) Comparative Test Data: Conventional mechanical vs. aerated cells: Recovery rate difference of ±3.5% 4.2 Process Control Systems Online Analyzer Configuration: ---Courier SLX (slurry XRF, analysis cycle: 90 s) ---Outotec PSI300 (particle size analysis, error 85%) Reuse Water Standards: ---Heavy metal ion concentrations (Pb²⁺65%) ---Sulfur concentrate production (combined magnetic separation-flotation, S grade >48%) Bulk Utilization Methods: ---Cement additive (15-20% blending ratio) ---Underground backfill material (slump control 18-22 cm)       Chapter 6: Techno-Economic Indicator Comparison 6.1 Typical Concentrator Operating Data Production Cost Structure: Cost Item Proportion (%) Unit Cost (USD/t)* Grinding Media 28-32 1.2-1.5 Flotation Reagents 18-22 0.75-1.05 Energy Consumption 25-28 1.05-1.35 *Note: Currency conversion at 1 CNY ≈ 0.15 USD 6.2 Technological Upgrade Benefits Case Study: 2,000 t/d Concentrator Retrofit Parameter Before Retrofit After Retrofit Improvement Zinc Recovery 82.3% 89.7% +7.4% Reagent Cost 6.8 CNY/t 5.2 CNY/t -23.5% Water Reuse Rate 65% 92% +27%       Chapter 7: Future Technological Development Directions 7.1 Short-Process Separation Technologies Superconducting Magnetic Separation (Background field intensity: 5 Tesla, processing -0.5mm material) Fluidized Bed Separation (Air-dense medium fluidized bed, Ecart Probable Ep=0.05) 7.2 Green Beneficiation Breakthroughs Bio-Reagent Development (e.g., Lipopeptide-based collectors) Zero-Tailings Mine Construction (Comprehensive utilization rate >95%)

1 Overview of Phosphate Ore Phosphate ores in nature are mainly classified into apatite-type (e.g., fluorapatite Ca₅(PO₄)₃F) and sedimentary phosphorite (e.g., collophanite). Due to significant variations in raw ore grades (P₂O₅ content ranging from 5% to 40%), beneficiation processes are typically required to enhance the grade to meet industrial standards (P₂O₅ ≥ 30%). Phosphate ores are rich in phosphorus, primarily used for extracting phosphorus and producing related chemical products, such as widely known phosphate fertilizers, as well as common industrial chemicals like yellow phosphorus and red phosphorus. These phosphorus-based materials, derived from phosphate ores, find extensive applications in agriculture, food, medicine, chemicals, textiles, glass, ceramics, and other industries. Given the generally high floatability of phosphate ores, flotation is the most commonly employed beneficiation method.       2 Phosphate Ore Beneficiation Methods   The selection of phosphate ore beneficiation processes depends on ore type, mineral composition, and dissemination characteristics. The primary methods include: Scrubbing and desliming, Gravity separation, Flotation, Magnetic separation, Chemical beneficiation, Photoelectric sorting, and Combined processes. 2.1 Scrubbing and Desliming Process This method is particularly suitable for heavily weathered phosphate ores with high clay content (such as certain sedimentary phosphorites). The technological process consists of: Crushing and Screening: Raw ore is crushed to appropriate particle size (e.g., below 20mm) Scrubbing: Employing scrubbers (like trough scrubbers) with water agitation to separate clay and fine slimes Desliming: Using hydrocyclones or spiral classifiers to remove slime particles smaller than 0.074mm Advantages: Features simple operation and low cost, capable of increasing P₂O₅ grade by 2-5% Limitations: Shows limited effectiveness for processing ores with closely intergrown minerals 2.2 Gravity Separation This method is applicable to ores where phosphate minerals and gangue exhibit significant density differences (e.g., apatite-quartz associations). Commonly used equipment includes: Jigging Machines: Ideal for processing coarse-grained ore (+0.5mm) Spiral Concentrators: Effective for medium-fine particle separation (0.1-0.5mm) Shaking Tables: Specialized for precision separation Advantages: Chemical-free process, making it particularly suitable for water-scarce regions Limitations: Relatively lower recovery rates (approximately 60-70%); Ineffective for processing ultra-fine particle ores 2.3 Flotation Method The most widely applied beneficiation technology for phosphate ores, particularly effective for processing: Low-grade collophanite ores, Complex disseminated ore types 2.3.1 Direct Flotation (Phosphate Mineral Flotation) Reagent Scheme: Collector: Fatty acids (e.g., oleic acid, oxidized paraffin soap) Depressant: Sodium silicate (for silicate depression), starch (for carbonate depression) pH Modifier: Sodium carbonate (adjusting pH to 9-10) Process Flow: ①Grind ore to 70-80% passing 0.074mm ②Condition pulp sequentially with depressants and collectors ③Float phosphate minerals ④Dewater concentrates to obtain final product Applicable Ore Type: Siliceous phosphate ore (phosphate-quartz association) 2.3.2 Reverse Flotation (Gangue Mineral Flotation) Reagent Scheme: Collector: Amine compounds (e.g., dodecylamine) for silicate flotation Depressant: Phosphoric acid for phosphate mineral depression Applicable Ores: Calcareous phosphate ores (phosphate-dolomite/calcite associations) 2.3.3 Double Reverse Flotation A two-stage process: ①Primary flotation of carbonates; ②Secondary flotation of silicates Applicability: Siliceous-calcareous phosphate ores (e.g., Yunnan/Guizhou deposits in China) Advantages: Capable of processing low-grade ores (P₂O₅

Under surface weathering conditions, primary sulfide minerals undergo oxidation reactions with atmospheric oxygen and aqueous solutions, forming secondary oxidized mineral zones. These oxidation zones typically develop in the shallow portions of ore deposits, with their thickness controlled by regional geological conditions, ranging between 10-50 meters.   Based on the oxidation degree of metallic elements in the ore (i.e., the percentage of oxidized minerals relative to total metal content), ores can be classified into three categories: Oxidized ore: oxidation rate >30% Sulfide ore: oxidation rate 10 (leads to PbS film detachment) Process optimizations: ✓ Partial NaHS substitution for Na₂S ✓ pH adjustment with (NH₄)₂SO₄ (1-2 kg/t) or H₂SO₄ ✓ Staged reagent addition (test-determined)   1.2. Zinc Oxide Minerals and Flotation Methods 1.2.1. Principal Industrial Zinc Oxide Minerals Mineral Chemical Formula Zinc Content Density (g/cm³) Hardness Smithsonite ZnCO₃ 52% 4.3 5 Hemimorphite H₂Zn₂SiO₅ 54% 3.3–3.6 4.5–5.0 1.2.2 Flotation Process Options 1.2.2.1. Hot Sulfidization Flotation Key Parameters: Pulp Temperature: 60–70°C (critical for ZnS film formation) Activator: CuSO₄ (0.2–0.5 kg/t) Collector: Xanthates (e.g., potassium amyl xanthate) Applicability: Effective for smithsonite Limited efficiency for hemimorphite 1.2.2.2. Fatty Amine Flotation Process Control: pH Adjustment: 10.5–11 (using Na₂S) Collector: Primary fatty amines (e.g., dodecylamine acetate) Slime Management: Option A: Pre-flotation desliming Option B: Dispersants (sodium hexametaphosphate + Na₂SiO₃) Innovative Approach: Amine-Na₂S emulsion (1:50 ratio) Eliminates need for desliming   1.3. Beneficiation Processes for Mixed Lead-Zinc Ores 1.3.1. Process Flow Options 1.3.1.1. Sulfides-First, Oxides-Later Circuit Sequence: Sulfide minerals (bulk/selective flotation) → Oxidized lead → Oxidized zinc Advantages: Maximizes sulfide recovery before oxide treatment Reduces reagent interference between mineral types 1.3.1.2. Lead-First, Zinc-Later Circuit Sequence: Lead sulfides → Lead oxides → Zinc sulfides → Zinc oxides Advantages: Ideal for ores with clear Pb/Zn liberation boundaries Enables tailored reagent schemes for each metal 1.3.2. Process Optimization Guidelines Highly oxidized ores (ZnO >30%): Use amine collectors to co-recover: Oxidized zinc minerals Residual zinc sulfides Typical dosage: 150–300 g/t C12–C18 amines Process selection criteria: Requires: Ore characterization studies (MLA/QEMSCAN) Bench-scale testing (including locked-cycle tests) Decision factors: Oxidation ratio (PbO/ZnO vs. PbS/ZnS) Mineralogical complexity index     2. Flotation Characteristics of Multivalent Metal Salt Minerals 2.1. Representative Minerals Phosphates: Apatite [Ca₅(PO₄)₃(F,Cl,OH)] Tungstates: Scheelite (CaWO₄) Fluorides: Fluorite (CaF₂) Sulfates: Barite (BaSO₄) Carbonates: Magnesite (MgCO₃) Siderite (FeCO₃) 2.2. Key Flotation Properties Characteristic Description Crystal Structure Dominant ionic bonding Surface Properties Strong hydrophilicity (contact angle

  The common main Copper Oxide minerals include: Malachite (CuCO3-Cu(OH)2, Copper 57.4%, density 4g/cm³, hardness 4); Azurite (2CuCO3 · Cu (OH)2, Copper 55.2%, density 4g/cm³, hardness 4). In addition, there are also Chrysocolla (CuSiO3 · 2H2O, Copper 36.2%r, density 2-2.2g/cm³, hardness 2-4) and Chalcopyrite (Cu2O, Copper 88.8%, density 5.8-6.2g/cm³, hardness 3.5-4).   Fatty acid collectors have good collection performance for non-ferrous metal oxide minerals, but due to poor selectivity (especially when the gangue is a carbonate mineral), it is difficult to improve the concentrate grade. Among the xanthate collectors, only high-grade xanthate has a certain collection effect on non-ferrous metal oxide minerals. However, the method of directly using xanthate flotation to Oxidize Copper ore without sulfurization treatment has not been widely used in industrial applications due to its high cost. In practical applications, the following methods are more common:   ① Sulfurization method -- the most common and simple process, suitable for flotation of all sulfidizable Copper Oxide ores. After sulfurization treatment, the oxidized ore has the characteristics of sulfide ore and can be floated using xanthate. Malachite and Chalcopyrite are easy to sulfide with sodium sulfide, while Siliceous Malachite and Chalcopyrite are more difficult to sulfide. During the sulfurization process, the dosage of sodium sulfide can reach 1-2kg/(t of raw ore). Due to the easy oxidation and short reaction time of sulfurizing reagents such as sodium sulfide, the generated sulfurized film is not stable enough, and strong stirring can easily cause detachment. Therefore, it should be added in batches without prior stirring and directly added to the first tank of the flotation machine. During sulfurization, the lower the pH value of the slurry, the faster the sulfurization rate. When there is a large amount of mineral mud that needs to be dispersed, a dispersant should be added, usually using sodium silicate. Generally, butyl xanthate or mixed with dithiophosphate is used as a collector. The pH value of the slurry is usually maintained at around 9. If it is too low, lime can be added appropriately to adjust it.   ② Organic acid flotation method -- Organic acids and their soaps can effectively float Malachite and Chalcopyrite. If the gangue mineral does not contain carbonates, this method is applicable; Otherwise, flotation will lose its selectivity. When the gangue is rich in floatable iron and manganese minerals, it can also lead to a deterioration of flotation indicators. When using organic acid collectors for flotation, sodium carbonate, sodium silicate, and phosphate are usually added as gangue depressants and slurry adjusters. There are also cases in practice where sulfurization method is combined with organic acid flotation method. Firstly, sodium sulfide and xanthate are used to flotation Copper Sulfide and partial copper oxide, followed by organic acid flotation of the remaining Copper Oxide.   ③ Leaching-precipitation-flotation method--used when both sulfurization and organic acid methods cannot obtain satisfactory results. This method utilizes the easy solubility of Copper Oxide minerals by first leaching the oxide ore with sulfuric acid, then replacing it with iron powder to precipitate Copper metal, and finally floating the precipitated Copper through flotation. Firstly, it is necessary to grind the mineral to a monomer dissociation state (-200 mesh accounting for 40%~80%) according to its embedding particle size. The leaching solution adopts a dilute sulfuric acid solution of 0.5%~3%, and the amount of acid is adjusted between 2.3~45kg/(t of raw ore) according to the properties of the ore. For ores that are difficult to leach, heating (45~70℃) leaching can be used. The flotation process is carried out in an acidic medium, and the collector is chosen to be cresol dithiophosphate or bis xanthate. The undissolved Copper sulfide minerals float up together with the precipitated Copper metal and eventually enter the flotation concentrate.   ④ Ammonia leaching-sulfide precipitation-flotation method -- suitable for situations where ores are rich in a large amount of alkaline gangue, acid leaching consumes a large amount and is costly. This method first grinds the ore finely, and then adds sulfur powder for ammonia leaching treatment. During the leaching process, Copper ions in the oxidized copper ore react with NH3 and CO2, while being precipitated by sulfur ions to form new copper sulfide particles. Next, ammonia is recovered by evaporation and copper sulfide flotation is carried out. The pH value of the slurry needs to be controlled between 6.5 and 7.5, and excellent flotation results can be achieved using conventional copper sulfide flotation reagents. It is worth noting that the recycling of ammonia must be taken seriously to prevent environmental pollution.   ⑤ Segregation-flotation -- its core is to mix ore with suitable particle size, 2%~3% coal powder, and 1%~2% salt, and then perform Chlorination reduction roasting in a high temperature environment of 700-800℃ to generate copper chloride. These chlorides evaporate from the ore and are reduced to metallic Copper in the furnace, which then adsorbs onto the surface of coal particles. Subsequently, Copper metal was effectively separated from gangue through flotation method. This method is particularly suitable for processing difficult to select copper oxide ores, especially complex Copper oxide ores with high mud content and combined Copper accounting for more than 30% of the total Copper content, as well as ores rich in Malachite and Chalcopyrite. In the comprehensive recovery of Gold, Silver, and other rare metals, the separation method exhibits significant advantages compared to the leaching flotation method. However, its disadvantage is that it consumes a large amount of heat energy, resulting in relatively high costs..   ⑥ Flotation of mixed Copper ore -- the flotation process of mixed Copper ore should be determined based on experimental results. The available processes include: firstly, synchronous flotation of oxidized minerals and sulfide minerals after sulfidation; The second is to first flotation sulfide minerals, and then flotation oxidized minerals after sulfidizing tailings. When simultaneously flotation Copper oxide minerals and Copper sulfide minerals, the process conditions are basically the same as those for flotation of oxide minerals, but it should be noted that as the oxide content in the ore decreases, the amount of sodium sulfide and collector should be correspondingly reduced. There are usually two main processes used for the treatment of Copper Oxide ores abroad: sulfide flotation and acid leaching precipitation flotation.