Iron is widely distributed in nature and is one of the earliest discovered and most commonly used metals. There are various types of iron ore with different grades. Iron can be selected through processes such as crushing, grinding, magnetic separation, flotation, and reselection. The main materials with high industrial value are magnetite, hematite, magnetite, ilmenite, limonite, and siderite.
1. Magnetite ore
Magnetite is a type of iron oxide ore, which is a common iron ore mineral. It appears black gray with metallic luster and black streaks. Magnetite is widely distributed in the Earth's crust and often coexists with other minerals. The iron content is 72.4% and it has magnetism. Magnetic separation method can be used in mineral processing, which is very convenient. Due to its fine structure, its reduction performance is poor. After long-term weathering, it becomes hematite.
2. Hematite
Hematite is also an iron oxide, with a surface color ranging from red to light gray, sometimes black, and dark red streaks. Commonly found in geological environments such as volcanic rocks and sedimentary rocks. Due to their different structural conditions, they can be divided into many categories, such as Red hematite, Specular hematite, Micaceous hematite, and Red Ocher. Pure hematite has an iron content of 70%, with less harmful impurities such as sulfur and phosphorus, and better reducibility than magnetite.
3. Limonite
This is an ore containing iron hydroxide, which is a general term for two different structured ores, goethite and phosphorite, and appears as earthy yellow or brown. Commonly found in geological layers such as mudstone and sandstone containing iron. Due to the weathering of other iron ores, brown iron ore has a relatively soft structure, low specific gravity, and high water content.
4. Titanium iron ore
Titanium iron ore is an oxide mineral of iron and titanium, appearing gray to black with a slight metallic luster, also known as titanium magnetite. The main application is to extract rare metal titanium.
5. Siderite
Siderite is an ore containing ferrous carbonate, mostly in a bluish gray color. This type of ore mostly contains a considerable amount of calcium and magnesium salts. Although its iron content is not high, it is easy to mine and process.
The common beneficiation methods for iron ore mainly include the following, and the beneficiation methods may vary for different types and characteristics of iron ore:
Ⅰ. Magnetic ore beneficiation method
1. Single weak magnetic separation process
Suitable for easily selected single magnetite ores with simple mineral composition.
It can be further divided into continuous grinding weak magnetic separation process and stage grinding stage separation process.
Continuous grinding weak magnetic separation process: suitable for ores with coarse particle size or high iron grade. According to the particle size of the iron ore, one stage grinding or two stages of continuous grinding can be used. After the grinding products meet the separation requirements, weak magnetic separation can be carried out.
Stage grinding stage separation process: suitable for low-grade ores with finer embedded particle size. After a stage of grinding, magnetic separation coarse selection is carried out, and some qualified tailings are discarded. The magnetic separation coarse concentrate then enters the second stage of grinding for further grinding and selection.
2. Weak magnetic separation reverse flotation process
Mainly aimed at the problem of difficulty in improving the grade of iron ore concentrate and the high composition of impurities such as SiO2 in iron concentrate. The process methods include two types: magnetic separation cation reverse flotation process and magnetic separation anion reverse flotation process.
3. Weak magnetic strong magnetic flotation combined process
Mainly used for processing polymetallic coexisting iron ores and mixed iron ores.
It is divided into weak magnetic separation flotation process, weak magnetic strong magnetic process, and weak magnetic strong magnetic flotation process.
Weak magnetic separation flotation process: mainly used for processing magnetite ore with associated sulfides.
Weak magnetic strong magnetic process: mainly used for processing mixed ores with low magnetic properties. Firstly, weak magnetic separation is used to separate weak magnetic magnetite, and then strong magnetic separation is used to recover weak magnetic minerals such as hematite from weak magnetic tailings.
Weak magnetic strong magnetic flotation process: used for processing more complex polymetallic coexisting iron ores.
Ⅱ. Mineral processing method for hematite ore
1. Roasting and magnetic separation process
When the mineral composition is relatively complex and other beneficiation methods are difficult to obtain good separation indicators, magnetization roasting method is often used.
For fine ore, methods such as strong magnetic separation, gravity separation, flotation, and their combined processes are commonly used for separation.
2. Flotation process of hematite
The flotation process methods include anionic collector forward flotation, cationic collector reverse flotation, and anionic collector reverse flotation, all of which have been applied in industry.
The reverse flotation process has advantages over the forward flotation process because the target of the reverse flotation process is gangue, while the target of the forward flotation process is iron minerals. The effective gravity of gangue in flotation pulp is far lower than that of iron minerals, so it is easier to separate gangue minerals in flotation foam by reverse flotation. Therefore, it is easier to separate gangue minerals in flotation foam by reverse flotation.
3. Weak magnetic strong magnetic process
The traditional process flow for processing magnet hematite mixed ore.
After the weak magnetic separation tailings are concentrated, they are subjected to strong magnetic coarse selection and scanning selection. The strong magnetic coarse concentrate is concentrated and then selected by a strong magnetic separator.
4. Strong magnetic flotation process
Due to the small amount of magnetite and other strong magnetic minerals in the ore, it is easy to cause blockage of the strong magnetic field separator, so when using the strong magnetic separation process. It is usually necessary to add a weak magnetic separation operation before the strong magnetic separation operation to remove or separate the strong magnetic minerals in the ore.
Ⅲ.Mineral processing method for brown iron ore
1. Single selection process
For ores with high iron grade and good selectivity. Usually, a simple single separation process is used, including reselection, high-intensity magnetic separation, and flotation.
Single re-election process: As the main sorting method for brown iron ore, re-election is mainly used to process coarse-grained disseminated ore.
Single magnetic separation process: Strong magnetic separation is also a commonly used method for separating limonite, with a simple process and convenient management. Has strong adaptability to ores, and concentrates are easy to concentrate and filter. But for fine-grained mineral mud, the separation effect is poor.
Single flotation process: flotation is divided into two process flows: forward flotation and reverse flotation.
2. Joint selection process
Including magnetization roasting magnetic separation process, flotation strong magnetic process, reselection strong magnetic process, etc.
Ⅳ.Mineral processing method for siderite ore
1. Roasting magnetic separation technology
Magnetic roasting principle: refers to the physical and chemical reactions that occur in a corresponding atmosphere after heating materials or ores to a certain temperature, thereby thermally decomposing weakly magnetic siderite into strongly magnetic magnetite and magnetite.
Magnetic roasting classification: Stacked state magnetic roasting, fluidized state magnetic roasting (cooling method will affect the effect of magnetic roasting of siderite).
2. Strong magnetic separation process: Siderite or magnesiosiderite has weak magnetism. Although the ore grade is low and the mineral composition is complex, strong magnetic separation technology can successfully separate weak magnetic iron minerals such as hematite and limonite, including siderite.
3. Flotation process: There are two main flotation processes: positive flotation for iron enrichment and reverse flotation for desilication.
The above is an introduction to commonly used methods for iron ore, and the specific situation should be determined based on the actual characteristics of the ore.
Recommend several reagents for iron ore flotation:
Titanium iron collector
【Characteristics】Black paste like solid
【Water soluble】Partially soluble in water
【Specification】750kg/pallet or 25kg/bag
【Typical applicable minerals】Ilmenite
【Function】This product is mainly used for flotation of ilmenite, with good selectivity and can significantly improve the grade of concentrate.
Red magnetite depressant
【Characteristics】White to light yellow powder
【Specification】25kg/bag, 50kg/bag, 1000kg/bag
【Function】Red magnetite depressant, when added to the slurry, can effectively improve the surface hydrophilicity of minerals such as hematite, magnetite, and limonite, effectively inhibiting them and achieving the improvement and reduction of impurities in iron concentrate. Mainly used for reverse flotation of iron ore.
Reverse flotation (silicate) collector
【Characteristics】Light yellow to yellow liquid
【Water soluble】Insoluble
【Specification】900kg/IBC drum
【Function】Efficient ether amine, suitable for removing silicates from hematite and magnetite, easy to biodegrade.
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