What Are The Commonly Used Mineral Processing Methods?
Heavy-Media Process
1. Method
The heavy medium beneficiation method utilizes the density differences (or particle size differences) of different ore particles in the ore, and creates an ideal loose layering and separation environment through the principles of fluid dynamics and various mechanical forces, in order to achieve effective separation of different materials.
2. Principle
According to Archimedes' principle, particles with a density lower than that of a heavy medium will float up, while particles with a density higher than that of a heavy medium will sink.
3. Process flow
The ore reselection process consists of a series of continuous operational steps. The nature of these operational steps can be divided into three main parts: preparation operation, selection operation, and product processing operation.
(1) The preparation process includes the following aspects:
a) The crushing and grinding operations carried out to dissociate useful mineral monomers;
b) For ores with high levels of pectin or clay, perform ore washing and desliming operations;
c) Particle size classification of selected ores is carried out through screening or hydraulic grading methods. After ore classification, they are selected separately, which is beneficial for selecting better operating conditions and improving sorting efficiency.
(2) The sorting operation is the core process of ore sorting. The complexity of the sorting process varies, and simple processes may only consist of a single unit operation, such as heavy medium sorting.
(3) The product processing operation mainly involves processes such as concentrate dewatering, tailings transportation, and storage.
Jigging
1. Principle
Jigging is a beneficiation method that utilizes the effect of vertical alternating medium flow to loosen the mineral particle group and stratify it according to density differences. During this process, lighter minerals will float to the upper layer, known as light products; And heavier minerals sink to the lower layer, called heavy products, to achieve mineral separation. If the density of the medium increases within a certain range, the density difference between mineral particles will also increase accordingly, thereby improving the sorting efficiency. The equipment that completes the jigs process is called a jigs. After being fed into the jig, the ore dressing material will fall onto the sieve plate to form a dense layer of material, which is called the bed layer. At the same time as the material is fed in, the lower part of the jigs is periodically supplied with alternating water flow. This vertical variable speed water flow enters the bed through the sieve holes, and the minerals undergo the jigs sorting process in this water flow.
2. Technological process
When the water flow rises, the bed is lifted up, presenting a loose and suspended state. At this point, the mineral particles in the bed begin to move relative to each other and undergo stratification based on their inherent characteristics such as density, particle size, and shape. Even before the water flow stops rising and turns downward, due to inertia, the mineral particles are still moving, and the bed continues to loosen and stratify. When the water flow turns downward, the bed gradually becomes tighter, but stratification is still ongoing. When all the mineral particles fall back onto the sieve surface, the possibility of relative motion between them is lost, and the stratification process basically stops. At this point, only those mineral particles with higher density and finer particle size pass through the gaps between the large blocks of material in the bed and continue to move downwards. This phenomenon can be seen as a continuation of the stratification phenomenon. When the descending water flow ends, the bed is completely tight and the stratification temporarily stops. The time required for the water flow to complete a periodic change is called the jig cycle. During a jig cycle, the bed undergoes a process of layering from tight to loose and then to tight again, and the particles are subjected to sorting. Only after multiple cycles of beating can the stratification gradually improve. Ultimately, high-density mineral particles concentrate in the lower part of the bed, while low-density mineral particles gather in the upper layer. Subsequently, two products with different densities and masses were obtained by discharging them separately from the jigs.
Flotation
1. Principle
Flotation is a mineral processing technique that utilizes the differences in physical and chemical properties of mineral surfaces for sorting.
2. Flotation process
The flotation process includes grinding, grading, slurry adjustment, as well as the coarse selection, fine selection, and sweeping stages of flotation. In these processes, the grinding flotation process can be subdivided into single-stage grinding flotation process, multi-stage process of segmented grinding flotation, and process of re grinding and re selection of concentrate or intermediate ore. In flotation operations, the step of producing coarse concentrate is called roughing; The process of re selecting coarse concentrate is called selection; The step of recycling tailings again is called scanning selection. When the goal is to recover multiple useful minerals from the ore, priority flotation or selective flotation processes can be selected based on mineral characteristics, that is, all useful minerals are first floated out before separation; Alternatively, a mixed separation flotation process can be adopted, where all useful minerals are first floated out before separation. In industrial production practice, it is necessary to select appropriate reagent formulas and flotation processes based on the characteristics of the ore and product requirements. The basic process of flotation, which is the core structure of the process flow, usually involves key elements such as the number of stages, the number of cycles, and the flotation sequence of minerals.
3. Flotation machine:
The types of flotation machines include mechanical agitation flotation machines, inflatable flotation machines, mixed flotation machines or inflatable agitation flotation machines, and gas precipitation flotation machines.
(1) The mechanical stirring flotation machine has the following characteristics: the aeration and stirring of the slurry are both achieved through a mechanical stirrer, and it is an external air self-priming flotation machine. Its inflatable mixer has the suction function of a pump, which can simultaneously suck up air and slurry.
(2) The significant features of the inflatable agitation flotation machine are: the aeration amount can be independently adjusted, the wear degree of the mechanical agitator is relatively small, the beneficiation index is superior, and the energy consumption is low.
(3) The characteristic of the Denver type flotation machine is that it has a large effective aeration capacity and can form an upward flow of slurry in the tank.
(4) The structural features of an inflatable flotation machine include the absence of mechanical agitators and transmission components. The inflation method is to inflate through an inflator, and the size of the bubbles can be controlled by adjusting the structure of the inflator. The mixing method of bubbles and slurry is countercurrent mixing. Its main application is to process rough and sweeping operations with simple composition, high grade, and easy beneficiation.
(5) Gas precipitation flotation machine is mainly used for the flotation of fine-grained minerals and the de oiling flotation of oily wastewater.
Magnetic Separation
1. Principle
Magnetic separation is a process that utilizes the magnetic differences between different ores or materials to separate them under the influence of magnetic and other related forces.
2. Magnetic Separation Process
The magnetic separation process is a magnetite beneficiation technology that combines dry and wet methods. This process mainly involves three-stage magnetic separation of mineral powder, followed by wet material magnetic separation. In the magnetic separation process, the magnetic field strength range used is 400 to 1200 Gauss (GS), and the speed of the magnetic drum is set between 60 to 320 revolutions per minute. After dehydration treatment, the wet material is converted into finished iron concentrate powder. For ores with a general iron content of 35%, after this magnetic separation process, the iron content of the iron concentrate powder can be increased to 68% to 70%. This joint process method has achieved a utilization rate of up to 90% for ore. During the manufacturing process, the water consumption is significantly reduced, thereby saving water resources, lowering production costs, and reducing environmental pollution. In addition, the dust generated during the magnetic separation process is effectively captured by specialized dust removal devices, avoiding air pollution. Overall, this method is an innovative process with high production efficiency, excellent product quality, and environmental friendliness.
Chemical beneficiation
1. Principle
Chemical beneficiation is a resource processing technology that uses chemical methods to change the composition of material components based on their chemical properties, and uses other methods to enrich the target components. This process mainly includes two key steps: chemical leaching and chemical separation.
2. Process:
(1) Usually, ores processed by chemical beneficiation are mostly lean, fine-grained, and complex ores. Based on the occurrence state of the target mineral, the roasting process is indispensable as it prepares for the subsequent leaching steps and facilitates the precipitation of the target mineral. Due to the existence of certain elements in minerals in the form of isomorphism, their precipitation process requires the destruction of the mineral lattice structure. According to the different additives, temperature, and pressure used, calcination can be divided into various types, such as chlorination calcination, calcification calcination, and high-temperature calcination.
(2) The purpose of the leaching step is to transfer useful elements in ionic form into the leaching solution, preparing for the subsequent solid-liquid separation steps. According to different leaching conditions, there are also various classifications of leaching processes, similar to roasting.
(3) Solid liquid separation refers to the process of separating the leached residue from the leachate.
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