Enrichment of minerals: basic methods, technologies and equipment

At the sight of valuable commodity minerals, the question arises as to how an attractive piece of jewelry can turn out from primary ore or a fossil. Especially in view of the fact that the processing of the rock as such is, if not one of the final, at least the final refinement process. The answer to the question will be the enrichment of minerals, during which the base processing of the rock takes place, which involves the separation of valuable minerals from empty media.

General Enrichment Technology

Processing of valuable minerals is carried out at special enrichment enterprises. The process involves several operations, among which preparation, direct splitting and separation of the rock with impurities. In the course of enrichment, different minerals are obtained, including graphite, asbestos, tungsten, ore materials, etc. Not necessarily this should be valuable rocks - there are many factories that perform processing of raw materials, which is further used in construction. In one way or another, the basics of mineral enrichment are based on an analysis of the properties of minerals, which also determine the principles of separation. By the way, the need for clipping of different structures does not only arise for the purpose of obtaining one pure mineral. It is common practice when several valuable species are derived from one structure.

Crushing of the rock

At this stage, the material is milled to individual particles. In the process of crushing, mechanical forces are used to overcome internal clutch mechanisms. As a result, the rock is divided into small solid particles, which have a homogeneous structure. In this case, it is worthwhile to distinguish between direct crushing and grinding technique. In the first case, the mineral raw material undergoes a less deep separation of the structure, during which the particles form a fraction of more than 5 mm. In turn, grinding provides the formation of elements with a diameter of less than 5 mm, although this figure depends on what kind of rock has to deal with. In both cases, the task is to maximize the splitting of the grains of the useful substance so that the pure component is freed without a mixt, that is, an empty rock, impurities, etc.

Screening process

After completion of the crushing process, the harvested raw material undergoes a different technological action, which can be both sifting and weathering. Screening in essence is a way of classifying the obtained grains according to the size characteristic. The traditional way of implementing this stage involves the use of sieves and sieves, provided with the possibility of calibrating cells. In the process of screening, the superlattices and sublattices are separated. In some ways, the enrichment of minerals begins at this stage, as some of the impurities and mixes are separated. A fine fraction with a size of less than 1 mm is screened out and by the air medium - by weathering. The mass, resembling fine-grained sand, rises with artificial air currents, after which it settles. Subsequently, particles that settle more slowly are separated from very small dust elements that are retained in the air. To further collect the derivatives of this screening, water is used.

Concentrating processes

The process of enrichment aims to separate the raw material from the raw material. During the implementation of such procedures, several groups of elements are distinguished: useful concentrate, dump tail and other products. The principle of separation of these particles is based on the differences between the properties of minerals and gangue. Such properties can be the following: density, wettability, magnetic susceptibility, size, electrical conductivity, shape, etc. Thus, enrichment processes using a difference in density involve gravitational separation methods. This approach is used in the processing of coal, ore and non-metallic raw materials. Extremely widespread and enrichment based on the wettability characteristics of the components. In this case, a flotation method is used, the feature of which is the possibility of separating fine grains.

It also uses magnetic mineral enrichment, which allows the release of ferruginous impurities from the talc and graphite media, as well as the purification of tungsten, titanium, iron and other ores. This technique is based on the difference in the effect of a magnetic field on fossil particles. As the equipment, special separators are used, which are also used to restore magnetite suspensions.

Final stages of enrichment

The main processes of this stage include dehydration, pulp thickening and drying of the particles obtained. Selection of equipment for dehydration is carried out on the basis of the chemical-physical characteristics of the mineral. As a rule, this procedure is performed in several sessions. However, the need for its implementation does not always arise. For example, if electrical separation was used in the enrichment process, dehydration is not required. In addition to the technological processes of preparation of the product of enrichment for further processing, the corresponding infrastructure for handling mineral particles must be provided. In particular, the factory organizes appropriate production services. In-house vehicles are being introduced, water, heat and electricity are being provided.

Enrichment equipment

At the stages of grinding and crushing, special settings are used. These are mechanical aggregates, which, with the help of various driving forces, have a destructive effect on the rock. Further in the screening process, a sieve and screen are used, in which the possibility of hole calibration is provided. Also used for sieving are more complex machines, which are called screens. Direct enrichment is performed by electric, gravitational and magnetic separators, which are used in accordance with the specific principle of separation of the structure. After that, drainage technologies are used for dehydration, in the implementation of which the same screens, elevators, centrifuges and filtration apparatuses can be used. The final stage, as a rule, involves the use of heat treatment and drying.

Wastes from the enrichment process

As a result of the enrichment process, several categories of products are formed, which can be divided into two types - useful concentrate and waste. And a valuable substance does not necessarily have to represent the same breed. Nor can it be said that waste is an unnecessary material. Such products may contain valuable concentrate, but in minimal amounts. Moreover, further enrichment of minerals that are in the waste structure often does not justify itself technologically and financially, therefore, secondary processes of such processing are rarely performed.

Optimum enrichment

Depending on the conditions of enrichment, the characteristics of the source material and the method itself, the quality of the final product may differ. The higher the content in it of a valuable component and less impurities, the better. The ideal enrichment of the ore, for example, provides for a complete absence of waste in the product. This means that in the process of enriching the mixture obtained by crushing and screening, litter particles from empty rocks were completely excluded from the total mass. However, it is not always possible to achieve such an effect.

Partial enrichment of minerals

Partial enrichment refers to the separation of a class of the size of a fossil, or the cutting off of an easily identifiable portion of impurities from the product. That is, this procedure does not purport to completely purify the product of impurities and waste, but only increases the value of the starting material by increasing the concentration of useful particles. Such processing of mineral raw materials can be used, for example, to reduce the ash content of coal. In the enrichment process, a large class of elements is isolated with further mixing of the concentrate of unenriched screening with a fine fraction.

The problem of loss of valuable rock during enrichment

As unnecessary impurities remain in the mass of the useful concentrate, so valuable rock can be excreted along with the waste. To take into account such losses, special tools are used to calculate the permissible level of these for each of the technological processes. That is, for all methods of separation, individual rates of allowable losses are developed. The permissible percentage is taken into account in the balance of processed products in order to cover differences in the calculation of the moisture ratio and mechanical losses. Especially such an accounting is important if it is planned to enrich the ore, during which deep crushing is used. Accordingly, the risk of losses of valuable concentrate also increases. And yet in most cases the loss of useful breed is due to violations in the technological process.

Conclusion

Recently, enrichment technologies for valuable rocks have made a significant step in their development. Both individual processing processes and general schemes for implementing the branch are being improved. One of the promising areas for further advancement is the use of combined treatment schemes that improve the quality characteristics of concentrates. In particular, magnetic separators are subjected to a combination, as a result of which the enrichment process is optimized. New methods of this type include magnetohydrodynamic and magnetohydrodystic separation. At the same time, the general tendency of deterioration of ore rocks is noted, which can not but affect the quality of the product obtained. To combat the increase in the level of impurities, it is possible to actively use partial enrichment, but in general the increase in processing sessions makes the technology ineffective.