When you see valuable commodity minerals, the question rightly arises of how such an attractive piece of jewelry can be obtained from primary ore or mineral. Especially taking into account the fact that the processing of the breed as such is, if not one of the final, then at least the refinement process preceding the final stage. The answer to the question will be mineral processing, during which the basic processing of the rock occurs, which involves the separation of valuable mineral from empty media.
General enrichment technology
Processing of valuable minerals is carried out at special enrichment enterprises. The process involves several operations, including preparation, direct cleavage and separation of the rock with impurities. In the course of enrichment, various minerals are obtained, including graphite, asbestos, tungsten, ore materials, etc. It does not have to be valuable rocks - there are many factories that process raw materials that are later used in construction. One way or another, the basics of mineral processing are based on an analysis of the properties of minerals, which also determine the principles of separation. By the way, the need to cut off various structures arises not only with the aim of obtaining one pure mineral. It is common practice when several valuable breeds are derived from one structure.
Rock crushing
At this stage, the material is crushed into individual particles. In the process of crushing, mechanical forces are involved, with the help of which the internal adhesion mechanisms are overcome.
As a result, the rock is divided into small solid particles that have a uniform structure. In this case, it is worth distinguishing between direct crushing and grinding technology. In the first case, mineral raw materials undergo a less deep separation of the structure, during which particles are formed with a fraction of more than 5 mm. In turn, grinding ensures the formation of elements with a diameter of less than 5 mm, although this indicator also depends on which breed you have 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 mixed, that is, waste rock, impurities, etc.
Screening process
After the completion of the crushing process, the harvested raw material is subjected to another technological impact, which can be both sieving and weathering. Screening is essentially a way of classifying grains obtained by size characteristics. The traditional way to implement this stage involves the use of a sieve and sieve, provided with the ability to calibrate the cells. In the process of screening, the superlattice and sublattice particles are separated. In a way, mineral processing begins already at this stage, since some of the impurities and mixtas are separated. The fine fraction with a size of less than 1 mm is screened out and with the help of air - weathering. A mass resembling fine sand rises with artificial air currents and then settles.
Subsequently, particles that settle more slowly are separated from very small dust elements that linger in the air. For further collection of derivatives of such screening, water is used.
Dressing processes
The enrichment process aims to isolate mineral particles from the feedstock. During the implementation of such procedures, several groups of elements are distinguished - a useful concentrate, dump tailings and other products. The principle of separation of these particles is based on the differences between the properties of minerals and waste rock. These properties may include the following: density, wettability, magnetic susceptibility, size, electrical conductivity, shape, etc. Thus, enrichment processes that use the difference in density involve gravitational separation methods. This approach is used in the processing of coal, ore and non-metallic raw materials. Enrichment based on the wettability characteristics of the components is also very common. In this case, the flotation method is used, the feature of which is the ability to separate thin grains.
Magnetic mineral processing is also used, which makes it possible to isolate ferrous impurities from talc and graphite media, as well as to purify tungsten, titanium, iron and other ores. This technique is based on the difference in the effect of a magnetic field on fossil particles. As equipment, special separators are used, which are also used to restore magnetite suspensions.
The final stages of enrichment
The main processes of this stage include dehydration, thickening of the pulp and drying of the resulting particles. The selection of equipment for dehydration is based on the chemical and physical characteristics of the mineral. As a rule, this procedure is performed in several sessions. Moreover, 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 for preparing the enrichment product for further processing processes, an appropriate infrastructure should be provided for handling mineral particles. In particular, the factory organizes appropriate production services. Intershop vehicles are being introduced, and water, heat and electricity supplies are being organized.
Enrichment equipment
At the stages of grinding and crushing, special plants are involved. These are mechanical units that, with the help of various drive forces, have a destructive effect on the rock. Further, in the process of screening, a sieve and a sieve are used, in which the possibility of calibrating the holes is provided. Also for sifting, more complex machines are used, 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 dewatering, 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.
Enrichment process waste
As a result of the enrichment process, several categories of products are formed, which can be divided into two types - useful concentrate and waste. Moreover, a valuable substance does not necessarily have to represent the same breed. It also cannot be said that waste is unnecessary material. Such products may contain valuable concentrate, but in minimal volumes. At the same time, 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.
Optimal enrichment
Depending on the conditions of enrichment, the characteristics of the starting material and the method itself, the quality of the final product may vary. The higher the content of a valuable component in it and the less impurities, the better. The ideal ore beneficiation, for example, involves the complete absence of waste in the product. This means that in the process of enrichment of the mixture obtained by crushing and screening, litter particles from waste rock were completely excluded from the total mass. However, this effect is far from always possible.
Partial Mineral Processing
Partial enrichment refers to the separation of the size class of a fossil or the cutting off of an easily separated portion of impurities from a product. That is, this procedure does not aim to completely clean the product from 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, in order to reduce the ash content of coal. In the process of enrichment, a large class of elements is released upon further mixing of the concentrate of non-enriched screenings with a fine fraction.
The problem of valuable rock loss during enrichment
As unnecessary impurities remain in the mass of useful concentrate, so valuable rock can be removed along with waste. To account for such losses, special tools are used to calculate the permissible level of these for each of the technological processes. That is, for all separation methods, individual norms of permissible losses are developed. The permissible percentage is taken into account in the balance of processed products in order to cover discrepancies in the calculation of moisture coefficient and mechanical losses. Such accounting is especially important if ore dressing is planned, in the process of which deep crushing is used. Accordingly, the risk of loss of valuable concentrate increases. And yet, in most cases, the loss of useful breed occurs due to violations in the process.
Conclusion
Recently, enrichment technologies for valuable breeds have taken a significant step in their development. Improved and individual processing processes, and general schemes for the implementation of the department. One of the promising areas of further advancement is the use of combined processing schemes that increase the quality characteristics of concentrates. In particular, magnetic separators are combined, as a result of which the enrichment process is optimized. New methods of this type include magnetohydrodynamic and magnetohydrostatic separation. At the same time, there is also a general tendency for ore ore to deteriorate, which cannot but affect the quality of the resulting product. It is possible to deal with an increase in the level of impurities by the active use of partial enrichment, but in general, an increase in processing sessions makes the technology ineffective.