What Steps Are Included in Iron Ore Beneficiation?

01Crushing and grinding in iron ore beneficiation

The crushing and grinding process includes crushing and screening operations, ore pre-selection operations before grinding, grinding and classification operations, etc. The energy consumption of the crushing and grinding system accounts for 50%-70% of the energy consumption of the entire mineral processing plant, of which the energy consumption of the grinding system accounts for more than 80% of the energy consumption of the crushing system. In order to reduce the grinding energy consumption, you can choose to reduce the grinding ore granularity. In order to reduce the grinding particle size, crushing equipment with large ratio, large crushing ratio, high efficiency and low consumption is used. Another way to reduce energy consumption is to perform pre-throwing before crushing, neutralization and grinding to reduce the load of subsequent grinding and sorting operations. Large-scale equipment is an important way to reduce energy consumption, so the mineral processing plant will choose to use large-sized autogenous grinding mills and ball mills for grinding operations. When iron ore is carrying out grinding and classification operations, high-efficiency classification equipment such as hydrocyclones, spiral classifiers and high-frequency fine screens are often used. These equipments play an important role in saving energy, reducing consumption and improving sorting indicators.

(Iron ore magnetic separation technology)

02Magnetic separation in iron ore beneficiation

Magnetic separation is the main method for selecting iron ore. It is mainly based on the magnetic differences in the materials to be separated. Different types of magnetic separators are used to separate different magnetic components in the materials. Magnetic separation methods can be divided into two methods: weak magnetic separation and strong magnetic separation.

Weak magnetic separation technology is suitable for strong magnetic iron minerals such as magnetite and vanadium, and mainly adopts stage grinding and stage magnetic separation. Throwing qualified tailings at each grinding stage can reduce the amount of regrinding in the next stage, reduce energy consumption, and improve the economic benefits of the mineral processing plant.

Strong magnetic separation technology is suitable for the processing of weakly magnetic minerals, such as hematite. Since the fine-grained iron minerals are not completely dissociated into monomers, a large amount of conjoined matter will enter the magnetic separation concentrate, resulting in low quality concentrate. Therefore, most mines will use strong magnetic separators as pretreatment equipment. The concentrator will discard qualified tailings as much as possible during the crushing and grinding stages to ensure metal recovery while improving the quality of the coarse concentrate.

(Iron ore flotation site)

03Flotation in iron ore beneficiation

Flotation is mainly suitable for the separation of fine-grained iron ore. Flotation method can be divided into forward flotation and reverse flotation. As the main method of iron ore beneficiation, positive flotation has the advantages of simple process flow, wide source of flotation reagents, and low price. The reverse flotation technology is suitable for iron ore beneficiation operations with relatively small gangue mineral content and types. Most reverse flotation processes use various methods to remove a large amount of gangue minerals to avoid affecting the flotation effect.

04Gravity separation in iron ore beneficiation

Gravity separation is one of the important methods for weakly magnetic iron ore. It can generally be divided into heavy media beneficiation, jig beneficiation, shaking table beneficiation and chute beneficiation. Heavy media beneficiation and jig beneficiation can be used to separate coarse-grained iron ore. Shaking table mineral processing has high separation accuracy and large enrichment ratio. However, the shaker has a small processing capacity per unit area and occupies a large area. It is sometimes used for the recovery of weakly magnetic iron minerals. Chute iron ore separation is widely used, and qualified concentrates with coarser particles can be obtained.

(Iron ore beneficiation)

05Iron ore combined beneficiation technology

If there are many types of iron minerals in the ore and the particle size is fine, it is difficult to recover the concentrate with a single mineral processing technology. In this case, it is necessary to use a combined mineral processing technology. Combined beneficiation technology can bring into play the advantages of magnetic separation, gravity separation, flotation and other methods, thereby improving the grade and recovery rate of the iron concentrate obtained. Therefore, joint beneficiation technology is a commonly used method for beneficiation of complex and difficult-to-benefit iron ore. The combined beneficiation technology can be applied to the separation of most weakly magnetic iron ores and mixed iron ores, and can also be applied to the separation of individual fine-grained highly magnetic iron ores.

(Thickener)

06Iron ore product processing technology

After the separation stage, the obtained iron ore concentrate needs to use concentration and filtration equipment to further improve the grade of the concentrate. Choosing efficient concentration equipment and technology can improve the processing capacity of the processing plant and reduce the floor space. Using more advanced filtration equipment and methods can improve filtration efficiency, reduce energy consumption and reduce product moisture content. After concentration and dehydration, the transportation cost of the product can be reduced and the production efficiency can be improved.

The above is the general mineral processing process used in iron ore beneficiation. The selection of specific iron ore beneficiation processes and equipment should be determined based on the properties and characteristics of the ore. Xinhai Mining recommends conducting mineral beneficiation test analysis to more accurately understand the selectivity of ore. Choosing the appropriate mineral processing technology and equipment can effectively improve the concentrate recovery rate and economic benefits.