Skarn-type scheelite beneficiation process

Skarn-type scheelite is an important type of tungsten ore, and its main mineral component is scheelite. This type of ore is usually formed in the contact zone between intermediate-acidic magmatic rocks and carbonate rocks, and has undergone complex skarnization. Its characteristics are complex mineral composition. In addition to scheelite, it is often accompanied by a variety of metal minerals, such as chalcopyrite, molybdenite, magnetite, etc., as well as non-metallic minerals such as garnet, diopside, calcite, quartz, etc. The distribution of scheelite in the ore varies greatly, ranging from coarse grains to fine grains, and has a close symbiotic relationship with gangue minerals. Some scheelite exists in the gangue minerals in the form of impregnation, fine veins or inclusions, which makes its beneficiation more difficult.

In order to continuously expand the application of tungsten in modern industry, it is necessary to develop skarn-type scheelite selection. Let us introduce what are the skarn-type scheelite selection methods?

1. Skarn-type scheelite gravity separation process

Gravity separation is based on the difference in mineral density. Under the action of external forces such as gravity field or centrifugal field, mineral particles of different densities are layered or graded according to density or particle size, thereby achieving mineral separation. The density of scheelite in skarn-type scheelite is about 6.1g/cm³, which is significantly different from most gangue minerals (such as garnet with a density of about 3.5-4.3g/cm³ and calcite with a density of about 2.71g/cm³), which provides a physical basis for gravity separation. During gravity separation, the mineral particles in the slurry are moved by water flow or mechanical force, and the dense scheelite particles tend to be enriched at the bottom of the equipment or in a specific area, while the gangue minerals with low density are distributed in other areas.

Gravity separation has a simple process, low equipment cost, convenient operation, no need to use chemical agents, and is environmentally friendly. For coarse-grained scheelite, gravity separation can quickly and effectively remove a large amount of gangue minerals, improve the grade of the selected ore, and has a high processing capacity. For example, in the pre-selection stage of some skarn-type scheelite concentrators, the use of gravity separation equipment such as jigs or shaking tables can pre-discard a large amount of low-density gangue minerals and reduce the processing volume of subsequent beneficiation processes.

However, the recovery effect of fine-grained scheelite is poor, the separation accuracy is relatively low, and it is difficult to obtain high-grade scheelite concentrate. Because fine-grained scheelite is small in mass during the gravity separation process, it is relatively complex to be subjected to gravity and fluid resistance, and is easily mixed with gangue minerals, and cannot be separated well.

2. Skarn-type scheelite flotation process

Flotation is based on the difference in the physical and chemical properties of the mineral surface, especially the wettability of the mineral surface to achieve mineral separation. In the flotation process of skarn-type scheelite, the properties of the slurry must be adjusted first. Generally, the pH value of the slurry is controlled between 9-10.5, and sodium carbonate is often used as a pH regulator.

Flotation has high sorting accuracy and can effectively separate scheelite from gangue minerals and other paragenetic metal minerals to obtain high-grade scheelite concentrate. It has good recovery effect on fine-grained minerals and can process skarn-type scheelite with finer embedded particle size.

However, the cost of flotation reagents is high, and some reagents are toxic, which is potentially harmful to the environment and the health of operators. The flotation process is relatively complex and requires precise control of multiple process parameters, such as pulp concentration, pH value, reagent addition amount, flotation time, etc., and the operation and management requirements are high. If the parameters are not properly controlled, it is easy to lead to poor flotation results, such as low concentrate grade, low recovery rate or excessive reagent consumption.

3. Magnetic separation process of skarn-type scheelite

Magnetic separation is to use the magnetic difference of minerals to carry out mineral separation. Although scheelite itself is a weakly magnetic mineral, there are often some magnetic minerals such as magnetite in skarn-type scheelite. In the process of magnetic separation, the ore is sent into the magnetic field of the magnetic separator, and the mineral particles with strong magnetism (such as magnetite) will be adsorbed on the magnetic pole by the magnetic field, while the non-magnetic or weakly magnetic minerals are not affected by the magnetic field, thereby achieving the separation of minerals. For some scheelite, after special treatment (such as roasting, etc.), its magnetic properties may change, and magnetic separation can also be used for separation.

For the treatment of skarn-type scheelite ore containing magnetic impurities, magnetic separation can effectively remove magnetic minerals and improve the efficiency of subsequent beneficiation processes and the quality of concentrates. Magnetic separation equipment is relatively simple, with low operating costs and little impact on the environment.

However, its application range is relatively narrow, and it is only effective for scheelite ores with certain magnetism or ores containing magnetic impurities. It is difficult to obtain high-purity scheelite concentrate using magnetic separation alone, and it usually needs to be used in combination with other beneficiation methods. Moreover, changes in the magnetic properties of scheelite often require additional pretreatment steps, such as roasting, which increases the complexity and cost of the process. Recommended: scheelite beneficiation equipment