The ore dressing and purification process is to separate valuable mineral components from the raw ore and remove unwanted impurities. According to different ore types and their physical and chemical properties, ore dressing and purification methods can be divided into many types, each of which has its specific working principle and application equipment. The following are several common ore dressing and purification methods, their basic principles and the main process equipment used:

1. Photoelectric sorting

Principle: Photoelectric sorting is a process of preliminary enrichment or direct acquisition of the final product based on the appearance characteristics (such as color, luster, shape) or specific physical properties (such as density, etc.) of minerals. This method is particularly suitable for minerals with obvious visual differences or physical properties.

Applicable minerals: quartz, pebbles, marble, limonite, wollastonite, phosphate rock, bauxite, limestone, talc, brucite, magnesite and other ores with obvious appearance characteristics or physical characteristics.

Application equipment: color sorter, artificial intelligence sorter, X-ray sorter, etc.

2. Ore washing

Principle: Ore washing is used to process ores containing a large amount of clay or other fine-grained impurities. By means of hydraulic flushing or mechanical stirring, the ore surface is cleaned and the dissociation between mineral particles is promoted, thus creating favorable conditions for subsequent separation operations.

Applicable minerals: Ores containing a large amount of clay or other fine-grained impurities, such as iron ore, manganese ore, bauxite, phosphate ore, etc.

Applicable equipment: spiral ore washer, vibrating screen, double spiral ore washer, etc.

3. Gravity separation

Principle: Gravity separation realizes layered transfer in an appropriate medium flow according to the different densities of the ore particles to achieve the purpose of separation. It includes various forms such as jig separation and shaking table separation. For some non-metallic minerals, centrifugal force is also used to enhance the separation effect, such as the separation of kaolin and gangue particles.

Applicable minerals: Ores with large density differences, such as tungsten-tin ore and coal; certain non-ferrous metals (such as lead and zinc), ferrous metals (such as iron), precious metals (such as gold) and non-metallic minerals (such as quartz sand, kaolin).

Applicable equipment: moving screen jig, shaking table, small cone angle cyclone group or centrifuge, etc.

4. Flotation

Principle: Flotation uses the difference in wettability of mineral surfaces. After adding appropriate reagents, minerals are separated in a gas-liquid-solid three-phase interface system. This method is widely used in the sorting of various fine-grained materials, especially when the mineral itself has low hardness and is easy to mud.

Applicable minerals: non-ferrous metal ores (such as copper, lead, zinc, sulfur, molybdenum, etc.), ferrous metals (such as magnetite and hematite in iron ore), rare metals (such as spodumene), non-metallic minerals (such as graphite, fluorite, barite, talc, etc.). Flotation is also one of the effective means of treating complex paragenetic ores.

Applied equipment: flotation machine, commonly used collectors include coal tar, and frothers include pine oil or butyl ether oil.

5. Magnetic separation

Principle: Magnetic separation is a technology that achieves separation based on the difference in magnetic properties between different minerals under the action of a magnetic field. It is one of the effective means to remove iron and other magnetic impurities, and is often used to purify non-metallic minerals such as talc and quartz sand.

Applicable minerals: Ores containing magnetic minerals, such as iron ore (hematite, magnetite), ilmenite, chromite, siderite, etc.; can also be used to remove iron impurities in non-metallic ores (such as quartz sand, feldspar, kaolin, talc, etc.).

Applicable equipment: iron remover, magnetic pulley, dry drum magnetic separator, permanent magnetic drum magnetic separator, induction roller magnetic separator, disc magnetic separator, high gradient magnetic separator, etc.4.

6. Electrostatic separation

Principle: Electrostatic separation relies on the difference in the electrical properties of minerals to complete the selective adsorption and separation of minerals in a high-voltage electric field environment. Although the application scope of this technology is relatively small, it still shows its unique advantages in specific occasions, such as the separation of rare minerals such as diamond and zircon.

Applicable minerals: Ores with different conductive properties, such as diamond, zircon, ilmenite and other rare minerals.

Applicable equipment: Roller corona-electrostatic composite electric field electrostatic separator.

7. Chemical beneficiation

Principle: Chemical beneficiation refers to the use of chemical reaction characteristics between minerals to separate minerals using chemical methods such as acid-base leaching and chlorination roasting. For example, for graphite with high purity requirements, the silicate impurities can be removed by acid leaching; and for insoluble fluorite, its purity can be improved by hydrofluoric acid treatment.

Applicable minerals: ores that need to be separated or purified by chemical reactions, such as using acid-base method to treat graphite to remove silicate impurities; using hydrofluoric acid to treat insoluble fluorite to improve its purity; or using leaching technology to extract gold from low-grade gold mines.

Applied equipment: reactor, leaching tank, etc.

8. Selective flocculation

Principle: Selective flocculation is to add specific polymer flocculants to make the target mineral form loose aggregates, while other minerals remain dispersed, and then combine gravity separation or flotation to separate mineral components. This method is particularly suitable for the separation of fine-grained minerals.

Applicable minerals: separation of fine-grained minerals, especially when there are significant differences in surface properties between these minerals, such as the selective flocculation flotation technology used in the treatment of fine-grained tin ore.

Applicable equipment: flocculant addition system, stirring barrel, etc.

9. Calcination or roasting

Principle: Calcination or roasting is to use the physical and chemical changes of minerals at high temperatures to change the mineral structure or remove volatile components. For example, kaolin can be calcined to remove structural water to form metakaolinite; while graphite can be roasted at high temperature to remove low-melting impurities and obtain higher-grade products.

Applicable minerals: ores that undergo physical and chemical changes at high temperatures to facilitate subsequent processing, such as kaolin can be calcined to remove structural water to form metakaolinite; graphite can be roasted at high temperatures to remove low-melting impurities to obtain higher-grade products; in addition, it also includes bauxite, magnesite, etc.

Applicable equipment: rotary kiln, vertical furnace, tunnel kiln, etc.

In summary, it is crucial to choose the appropriate mineral processing and purification method for specific ore types and needs. At the same time, with the advancement of science and technology, new technologies and equipment continue to emerge, which improves the efficiency of mineral processing while reducing costs and promoting the effective use of resources. These methods and technologies are not limited to metal ores, but are also applicable to the processing of non-metallic ores.