Magnetic Separation of Non-ferrous Metals And Rare Metal Ores

Magnetic separation of non-ferrous metal ores and rare metal ores is an important separation technology in mineral processing, mainly using the magnetic difference of minerals in the ore for separation.

 

Non-ferrous metal ores

Common minerals in non-ferrous metal ores include:

• Bauxite (the main ore of aluminum)
• Copper ores (such as chalcocite, chalcopyrite)
• Lead-zinc ores (such as galena, sphalerite)
• Nickel ores (such as pyrite, pentlandite)

 

Rare metal ores

Rare metal ores (such as tungsten, molybdenum, lithium, niobium, tantalum, etc.) can also be processed by magnetic separation. For example:

• Magnetic minerals in tungsten ores (such as wolframite) can be separated by magnetic separation technology.
• Impurity minerals in lithium ores (such as spodumene) can sometimes also be removed by magnetic separation.

 

 

Magnetic Separation

Magnetic separation is a method of physically separating minerals by magnetic force. Magnetic minerals can be attracted to magnets, while non-magnetic minerals are not. This method is widely used in the beneficiation process of non-ferrous metal ores. The magnetic separation method can be divided into two kinds of dry and wet methods, the dry method is suitable for ores with larger particle sizes, and the wet method is suitable for ores with smaller particle sizes.

 

The advantages of magnetic separation

1. High efficiency: magnetic separation can efficiently separate magnetic and non-magnetic minerals, greatly improving the beneficiation efficiency.
2. Flexible: The magnetic separation method can be adjusted by adjusting the magnetic field strength and magnetic field direction to adapt to different types of ores and particle sizes and has a high degree of flexibility.
3. Environmental protection: magnetic separation does not require the use of chemical reagents, no pollution of the environment.

 

The limitations of magnetic separation

1. Limited beneficiation effect: magnetic separation can only separate minerals with a certain degree of magnetism, for non-magnetic minerals can not be separated, so the beneficiation effect is limited.
2. High cost of equipment: the cost of magnetic separation equipment is relatively high, which may not be economical for small mines.
3. High operation technology requirements: magnetic separation requires operators to have a high technical level and experience, otherwise it may affect the beneficiation effect.

 

The use of magnetic separation for non-ferrous metal ores has certain advantages and limitations. In the beneficiation process, the appropriate beneficiation method should be selected based on comprehensive considerations such as ore type and particle size to achieve the best beneficiation effect.

 

 

Non-ferrous Metals And Rare Metal Ores Processing

In the mining and processing of some non-ferrous and rare metal ores (e.g., vein tungsten ore, vein tin ore, alluvial tin ore and seaside alluvial ore, etc.), a notable feature is that they are usually enriched with a variety of magnetic minerals, such as magnetite, hematite, magnetopyrite, ilmenite, wolframite, tantalite, niobium iron ore, and monazite. Given that these metallic minerals are generally denser than chalcopyrite minerals, the first step in the beneficiation process is often gravity separation, which takes advantage of the density differences between the minerals to enrich them and produce a mixed coarse concentrate initially. Gravity separation relies on equipment such as shaking tables, spiral chutes, centrifugal concentrators, and jig separators, effectively separating metallic minerals from the mixture based on density differences.

 

The rough concentrate is then dried and screened, and subdivided into different grades based on its size composition, and mineral properties, to provide a more homogeneous raw material for the subsequent concentrating operation, thus improving the overall efficiency of the beneficiation process. At the concentrating stage, depending on the specific composition, particle size, and other physicochemical properties of the crude concentrate, a single magnetic separation method or a more complex combined beneficiation process is flexibly selected.

 

Single Magnetic Separation

The single magnetic separation method is mainly applied to the minerals with strong magnetic properties, such as magnetite, ilmenite, and magnetic pyrite, to realize the effective separation of magnetic minerals and non-magnetic minerals under the action of the magnetic field through the magnetic separator, the commonly used magnetic separation equipment covers dry, wet and high gradient magnetic separator, the method is known for its easy operation and high efficiency.

 

Combined Beneficiation Process 

The combined beneficiation process applies to the combination of minerals with more complex composition and less significant magnetic difference, which combines magnetic separation with other beneficiation techniques, such as flotation, particle flotation, electrostatic separation, and gravity separation, aiming to improve the quality of concentrate and the comprehensive utilization of resources. Specific combination methods include:

Magnetic Separation-Flotation: For rough concentrates containing sulfide or oxide ores, which are pre-treated by magnetic separation, and then flotation technology is used to recover specific minerals.

Magnetic Separation-Electrostatic Separation: For scenarios where there are significant differences in electrical conductivity between minerals, such as the separation of ilmenite from monazite.

Magnetic Separation-Gravity Separation: For minerals with large particle sizes or significant density differences, gravity separation is used as a preliminary enrichment means, followed by magnetic separation for further purification.

Magnetic Separation-Particle Flotation: Especially suitable for coarse-grained minerals, magnetic separation first separates the magnetic components, and particle flotation is used to recover the non-magnetic parts.

 

While pursuing economic benefits, the comprehensive utilization of mineral resources and environmental protection are equally important. For example, in the beneficiation of tungsten and tin ores, not only the main metal is recovered, but also the associated rare metals such as tantalum, niobium, and rare earth are recovered. At the same time, in response to the global environmental protection trend, the beneficiation process needs to reduce pollutant emissions, promote green beneficiation technology and environmentally friendly agents, and ensure the sustainable development of mineral resources.

 

Generally speaking, for nonferrous and rare metal ores containing multiple magnetic minerals, selecting a gravity separation, single magnetic separation, or combined beneficiation process based on mineral characteristics is an effective way to improve the quality of concentrate and resource utilization.