Copper can be produced as a main product or as a co-product, gold, lead, zinc and silver. It is mined in the Northern and Southern Hemispheres and primarily consumed in the Northern Hemisphere with the US as the main producer and consumer.

The copper processing plant recycles copper from metal ore and scrap copper. The leading consumers of copper are wire mills and copper mills, which use copper to produce copper wire, etc. The end use of copper includes building materials, electronic products, transportation and equipment.

Copper is mined in quarries and underground. The ores typically contain less than 1% copper and are often associated with sulfide minerals. The ore is crushed, concentrated, and suspended with water and chemicals. Blowing air through the mixture attached to the copper will cause it to float on top of the sludge.

Crushing complex for copper ore

Large copper ore raw materials are fed into the copper ore jaw crusher evenly and gradually by vibrating feeder through the primary crushing hopper of copper ore. Once parted, the crushed pieces of copper ore can meet the standard and be taken as the final product.

After the first crushing, the material will be transferred to copper ore impact crusher, copper ore cone crusher, secondary crusher conveyor. Then the crushed materials are transferred to a vibrating sieve for separation. The final copper ore products will be taken away, and the other copper ore parts will be returned to the copper ore impact crusher, forming a closed circuit.

The dimensions of the final copper ore product can be combined and evaluated according to the requirement of the customers. We can also equip environmental protection ash removal systems.

Mill complex for copper ore

After primary and recycling in the copper ore production line, it can go to the next stage to grind copper ore. The final copper ore powder produced by Zenith Copper Ore Milling Equipment typically contains less than 1% copper, while the sulfide ores have moved to the beneficiation stage, while the oxidized ores are used for leaching tanks.

The most popular copper ore milling equipment is ball mills. ball mill plays important role in copper ore grinding process. Zenith ball mill is an efficient tool for grinding copper ore into powder. There are two grinding methods: dry process and wet process. It can be divided into table type and flow type according to various forms material unloading. The ball mill is the crucial equipment for grinding after the materials are crushed. This effective tool for grinding i various materials into powder.

It can also be used with mills such as European type MTW trapezoidal mill, XZM superfine mill, MCF coarse powder mill, vertical mill, etc.

Copper ore has a different composition, which affects its quality characteristics and determines the choice of the method of enrichment of the feedstock. The composition of the rock can be dominated by sulfides, oxidized copper, and a mixed amount of components. At the same time, in relation to ore mined in the Russian Federation, the flotation enrichment method is used.

Processing of sulfide copper ore of disseminated and continuous type, which contains no more than a quarter of oxidized copper, is carried out in Russia at processing plants:

  • Balkhash;
  • Dzhezkazganskaya;
  • Sredneuralskaya;
  • Krasnouralskaya.

The raw material processing technology is selected according to the type of raw material.

Work with disseminated ores involves the extraction of sulfides from the rock and their transfer to depleted concentrates using chemical compounds: blowing agents, hydrocarbons and xanthate. Rather coarse grinding of the rock is used primarily. After processing, the poor concentrate and middlings pass additional process grinding and cleaning. During processing, copper is released from intergrowths with pyrite, quartz and other minerals.

The homogeneity of the porosity ore supplied for processing ensures the possibility of its flotation at large enrichment enterprises. High level productivity allows to achieve a reduction in the cost of the enrichment procedure, as well as to accept ore with a low copper content (up to 0.5%) for processing.

Schemes of the flotation process

The flotation process itself is built according to several basic schemes, each of which differs both in the level of complexity and cost. The simplest (cheapest) scheme provides for a transition to an open ore processing cycle (at the 3rd stage of crushing), ore grinding within one stage, as well as a subsequent regrinding procedure with a result of 0.074 mm.

During the flotation process, the pyrite contained in the ore is subjected to depression, leaving a sufficient level of sulfur in the concentrates, which is necessary for the subsequent production of slag (matte). For depression, a solution of lime or cyanide is used.

Solid sulfide ores (cuprous pyrites) are distinguished by the presence of a significant amount of copper-bearing minerals (sulfates) and pyrite. Copper sulfides form thin films (covellite) on pyrite, while, due to the complexity chemical composition the floatability of such ore is somewhat reduced. For efficient process enrichment requires careful grinding of the rock in order to facilitate the release of copper sulfides. It is noteworthy that in a number of cases, thorough grinding is devoid of economic feasibility. It's about about situations where a pyrite concentrate subjected to a roasting process is used in blast-furnace smelting in order to extract precious metals.

Flotation is carried out when creating an alkaline medium of high concentration. In the process, the following proportions are used:

  • lime;
  • xanthate;
  • fleetoil.

The procedure is quite energy intensive (up to 35 kWh/t), which increases production costs.

The process of grinding ore is also complex. As part of its implementation, multi-stage and multi-stage processing of the source material is provided.

Enrichment of intermediate type ore

The processing of ore with a sulfide content of up to 50% is similar in technology to the enrichment of solid sulfide ore. The difference is only the degree of its grinding. The material of a coarser fraction is accepted for processing. In addition, the separation of pyrite does not require the preparation of a medium with such a high alkali content.

Collective flotation followed by selective processing is practiced at the Pyshminskaya concentrator. The technology makes it possible to use 0.6% ore to obtain 27% copper concentrate with subsequent recovery of over 91% copper. Works are carried out in an alkaline environment with different levels of intensity at each stage. The processing scheme allows to reduce the consumption of reagents.

Technology of combined enrichment methods

It is worth noting that ore with a low content of impurities of clay and iron hydroxide lends itself better to the enrichment process. The flotation method makes it possible to extract up to 85% of copper from it. If we talk about refractory ores, then the use of more expensive combined enrichment methods, for example, the technology of V. Mostovich, becomes more effective. Its application is relevant for Russian industry, since the amount of refractory ore is a significant part of the total production of copper-bearing ore.

The technological process involves the crushing of raw materials (fraction size up to 6 mm) followed by immersion of the material in a solution of sulfuric acid. This allows sand and sludge to be separated, and free copper to go into solution. The sand is washed, leached, passed through a classifier, crushed and floated. The copper solution is combined with the sludge and then subjected to leaching, cementation and flotation.

In the work according to the Mostovich method, sulfuric acid is used, as well as precipitating components. The use of technology turns out to be more costly in comparison with operation according to the standard flotation scheme.

The use of an alternative scheme of Mostovich, which provides for the recovery of copper from oxide with flotation after crushing of heat-treated ore, makes it possible to somewhat reduce costs. To reduce the cost of technology allows the use of inexpensive fuel.

Flotation of copper-zinc ore

The process of flotation of copper-zinc ore is labor intensive. Difficulties explained chemical reactions occurring with multicomponent raw materials. If the situation is somewhat simpler with primary sulfide copper-zinc ore, then the situation when exchange reactions began with the ore already in the deposit itself can complicate the enrichment process. Conducting selective flotation, when dissolved copper and films of cavellin are present in the ore, may become impossible. Most often, such a picture occurs with ore mined from the upper horizons.

In the beneficiation of the Ural ore, which is rather poor in terms of copper and zinc, the technology of both selective and collective flotation is effectively used. At the same time, the method of combined ore processing and the scheme of collective selective enrichment are increasingly used at the leading enterprises of the industry.

Ores extracted from the bowels of the earth or technogenic raw materials in most cases cannot be directly used in metallurgical production and therefore go through a complex cycle of successive operations. preparation for blast furnace. Note that when ore is mined by opencast mining, depending on the distance between the blast holes and the size of the excavator bucket, the size of large blocks iron ore can reach 1000-1500 mm. In underground mining, the maximum size of a piece usually does not exceed 350 mm. In all cases, the extracted raw materials contain and a large number of small fractions.

Regardless of the subsequent scheme for preparing the ore for smelting, all mined ore goes through, first of all, the stage primary crushing, since the size of large pieces and blocks during mining far exceeds the size of an ore piece, the maximum allowable according to the conditions of blast-furnace smelting technology. Specifications for lumpiness, depending on the reducibility, the following maximum size of ore pieces is provided: up to 50 mm for magnetite ores, up to 80 mm for hematite ores and up to 120 mm for brown iron ore. The upper limit of the particle size of agglomerate pieces should not exceed 40 mm.

Figure 1 shows the most common crusher installations in crushing and screening plants. Schemes a and b solve the same problem of crushing ore from

Figure 1. Scheme of crushing iron ore
a - "open"; b - "open" with preliminary screening; c - "closed" with preliminary and verification screening

At the same time, the principle “do not crush anything superfluous” is implemented. Schemes a and b are characterized by the fact that the size of the crushed product is not checked, i.e., the schemes are "open". Experience shows that in a crushed product there is always a small number of pieces, the size of which is somewhat larger than the specified one. In "closed" ("closed") circuits, the crushed product is again sent to the screen to separate insufficiently crushed pieces with their subsequent return to the crusher. With “closed” ore crushing schemes, compliance with the upper limit of crushed product size is guaranteed.

The most common types of crushers are:

  • conical;
  • jaw crushers;
  • roller;
  • hammer.

The device of crushers is shown in fig. 2. The destruction of pieces of ore in them occurs as a result of crushing, splitting, abrading forces and impacts. In the Black jaw crusher, the material introduced into the crusher from above is crushed by the oscillating 2 and fixed 1 cheeks, and in the McCouley cone crusher, by the fixed 12 and rotating internal 13 cones. The shaft of the cone 13 enters the rotating eccentric 18. In the jaw crusher, only one stroke of the movable jaw is working, during the reverse stroke of the jaw, part of the crushed material has time to leave the working space of the crusher through the lower outlet slot.

Figure 2. Structural schemes crushers
a - cheek; b - conical; c - mushroom-shaped; g - hammer; d - roll;
1 - fixed cheek with an axis of rotation; 2 - movable cheek; 3, 4 - eccentric shaft; 5 - connecting rod; 6 - hinged support of the rear spacer cheek; 7 - spring; 8, 9 - mechanism for adjusting the width of the unloading gap; 10 - thrust of the closing device; 11 - bed; 12 - fixed cone; 13 - movable cone; 14 - traverse; 15 - suspension hinge of the movable cone; 16 - cone shaft; 17 - drive shaft; 18 - eccentric; 19 - damping spring; 20 - support ring; 21 - regulating ring; 22 - cone thrust; 23 - rotor; 24 - impact plates; 25 - grate; 26 - hammer; 27 - main frame; 28 - crushing rolls

The capacity of the largest jaw crushers does not exceed 450-500 t/h. Typical for jaw crushers are cases of press-fitting of the working space during crushing of wet clay ores. In addition, jaw crushers should not be used for crushing ores that have a slate slate structure of the piece, since individual tiles, if their long axis is oriented along the axis of the slot for dispensing crushed material, can pass through the working space of the crusher without being destroyed.

The supply of jaw crushers with material must be uniform, for which the apron feeder is installed from the side of the crusher's fixed jaw. Jaw crushers are usually used for crushing large pieces of ore (i = 3-8). Electricity consumption for crushing 1 ton of iron ore in these plants can vary from 0.3 to 1.3 kWh.

In a cone crusher, the axis of rotation of the inner cone does not coincide with the geometric axis of the fixed cone, i.e., at any moment, ore crushing occurs in the zone of approach of the surfaces of the inner and outer fixed cones. At the same time, in the remaining zones, the crushed product is dispensed through the annular gap between the cones. Thus crushing of ore in a cone crusher is carried out continuously. Achievable productivity is 3500-4000 t/h (i = 3-8) with power consumption for crushing 1 ton of ore 0.1-1.3 kWh.

cone crushers can be successfully used for ores of any type, including those with a layered (platy) structure of the piece, as well as for clay ores. Cone crushers do not need feeders and can operate “under the rubble”, i.e. with a working space completely filled with ore coming from a bunker located above.

The Simons Short Cone Mushroom Crusher differs from the conventional cone crusher in that it has an elongated crushed product delivery zone, which ensures that the material is completely crushed to the desired size of the pieces.

IN hammer crushers crushing of ore is carried out mainly under the influence of blows on them by steel hammers mounted on a rapidly rotating shaft. At metallurgical plants, limestone is crushed in such crushers, which is then used in sinter shops. Brittle materials (eg coke) can be crushed in roller crushers.

After primary crushing, rich low-sulphurous ore with a fraction > 8 mm can be used by blast-furnace shops, fraction Some of the fine fractions are still absorbed by the furnace, sharply worsening the gas permeability of the charge column, since small particles fill the space between larger pieces. It must be remembered that the separation of fines from the blast-furnace charge in all cases gives a significant technical and economic effect, improving the course of the process, stabilizing dust removal at a constant minimum level, which in turn contributes to the constant heating of the furnace and reducing coke consumption.

The task of these operations is the complete or partial disclosure of grains of gold-bearing minerals, mainly particles of native gold, and bringing the ore into a state that ensures the successful flow of subsequent enrichment and hydrometallurgical processes. Crushing and especially fine grinding operations are energy-intensive, and their costs account for a significant proportion of the total cost of ore processing (from 40 to 60%). Therefore, it must be borne in mind that grinding should always be completed at the stage when they are sufficiently opened for their final extraction or for their intermediate concentration.

Since the main method of extracting gold and silver for most ores is hydrometallurgical operations, the necessary degree of grinding should ensure the possibility of contact of solutions with open grains of gold and silver minerals. The sufficiency of opening these minerals for a given ore is usually determined by preliminary laboratory technological tests for the extraction of precious metals. To do this, ore samples are subjected to technological processing after varying degrees of grinding while simultaneously determining the recovery of gold and accompanying silver. It is clear that the finer the dissemination of gold, the deeper the grinding should be. For ores with coarse gold, coarse grinding (90% grade -0.4 mm) is usually sufficient. But since in most ores along with coarse gold there is also fine gold, most often the ores are ground more finely (up to -0.074 mm). In some cases, the ore has to be subjected to even finer grinding (up to 0.044 mm).

An economically viable degree of grinding is established taking into account a number of factors;

1) the degree of extraction of metal from the ore;

2) an increase in the consumption of reagents with more intensive grinding;

3) the cost of additional grinding when bringing the ore to a given size;

4) deterioration in the thickening and filterability of finely divided ores and related additional costs for thickening and filtering operations.

Schemes of crushing and grinding vary depending on the material composition of ores and their physical properties. As a rule, the ore is first subjected to coarse and medium crushing in jaw and cone crushers with verification screening. Sometimes a third stage of fine crushing is used, carried out in short-cone crushers. After a two-stage crushing, a material with a particle size of 20 mm is usually obtained; after a three-stage crushing, the material size is sometimes reduced to 6 mm.

The crushed material goes to wet grinding, which is most often carried out in ball and rod mills. Ores are usually reduced in several stages. The most widely used two-stage grinding, and, for the first stage, it is preferable to use rod mills, which give a product more uniform in size with less overgrinding.

At present, ore and ore-pebble self-grinding has become widespread in the ore preparation cycle at gold mining enterprises. In ore self-grinding, the grinding media are unsized pieces of the ore being ground itself, only some control over the upper size of the pieces is provided. In the case of ore-pebble self-grinding, the grinding medium is a fraction of pieces of crushed ore (galya) specially distinguished by size and strength.

Ore self-grinding is carried out in air or aquatic environment in special mills, in which, compared to conventional ball mills, the ratio of the diameter to the length of the mill is increased. Since the grinding effect of ore lumps is worse than steel balls, the diameter of self-grinding mills reaches 5.5-11.0 m.

For dry self-grinding, an Aerofol mill is used. It is a short drum mounted on a massive foundation. On the inner surface of the drum along its generatrix, at some distance from one another, shelves of I-beams or rails are installed, which, when the drum rotates, raise pieces of ore. As they fall, the pieces crush the ore below, and besides, hitting the shelves as they fall, large pieces split. On the end caps of the drum, guide rings of triangular section are fixed, the purpose of which is to direct the pieces to the middle of the drum. The mill rotation speed is 80-85% of the critical speed.

The crushing of ores in Aerofol mills provides a more uniform product in comparison with grinding in conventional ball mills. In Aerofol mills, ore regrinding is reduced, which improves the filterability and thickening of the resulting pulps. After grinding in these mills, the indicators of hydrometallurgical processing also improve: the consumption of reagents (cyanide) is reduced by 35%, and gold recovery is increased (up to 4%). Dry ballless grinding of gold ores is more economical in some cases. However, it imposes stringent requirements on the moisture content in the ore (no more than 1.5-2%). An increase in humidity drastically reduces the efficiency of grinding and classification processes. In addition, dry grinding is accompanied by large dust formation, which requires a developed dust collection system and worsens working conditions. Therefore, self-grinding in an aquatic environment is more common.

Wet ore self-grinding is carried out in Cascade mills. This mill has a short drum with conicalend caps. Hollow trunnions and the drum rests on bearings. The ore from the mill is unloaded through the grate. Cascade mills operate in a closed cycle with a mechanical classifier or hydrocyclones.

Ore-pebble self-grinding is carried out, as a rule, in the aquatic environment. The designs of ore-pebble and ball mills with grate discharge are similar.

The size of the ore gallstone used as the grinding medium is determined by the grinding stage. At the first stage of grinding, halyards with a size of -300 + 100 mm are usually used, at the second - 100 + 25 mm. Elimination of hali is carried out on screens. The shape of the halyard for grinding does not matter.

In the schemes of processing gold ores, a significant place is occupied by the operations of classifying the crushed material by size. IN Lately at most gold recovery factories, hydrocyclones of various designs are widely used as a classifier at all stages of processing, including in a closed primary grinding cycle, instead of spiral, rack and bowl classifiers. Rough classification of mill products is in some cases carried out by screening in drum screens mounted at the discharge ends of the mills.

Before hydrometallurgical treatment or enrichment by flotation, gold ores are deslimed if the sludge is depleted in gold and adversely affects technological operations. Hydrocyclones or thickeners are used for desludge bathing. By such methods, up to 30-40% of sharply depleted material is sometimes removed to the dump, which not only improves technological performance, but also reduces the amount of equipment for subsequent operations.

Sorting and primary enrichment of lumpy ore

Usually, in the mined rock mass, along with pieces of gold-bearing ore, there are also pieces of waste rock, the exclusion of which from subsequent processing can significantly improve technical and economic indicators.

To remove waste rock, sometimes manual sorting is used. At the same time, waste rock is either removed from the rock mass, or an ore fraction enriched with gold is isolated. General rule sorting is that the output rock in terms of gold content should not be richer than the tailings of the gold recovery plant.

Typically, ore sorting is used for material larger than 40-5C mm. The sorting conveyor belts are given a vibrating motion to improve the inspection of the pieces. However, manual sorting of ores is a laborious and inefficient process. Therefore, it is not currently used (with the exception of a few enterprises in South Africa).

IN last years Advances in science and technology have made it possible to replace manual sorting with more rational and economically viable methods of preliminary enrichment of relatively large lumpy ore, in particular, the enrichment process in heavy environments, fully mechanized and fairly simple in design. The most promising application of enrichment in heavy media to sulfide ores, in which it is associated only with sulfides, is evenly distributed, and its content in the enriched raw material is almost proportional to the content of sulfides. Therefore, when enriched in heavy media, together with sulfides, it is concentrated in heavy fractions; the light fractions contain host rocks that are almost not mineralized for this group of gold-bearing ores.

Machines that are used for crushing - crushers, can reduce the size of the pieces to 5-6 mm. Finer crushing is called grinding, it is carried out in mills.

In most cases, crushing together with grinding are preparatory operations before ore dressing. Although crushing in one unit is possible from 1500 mm, for example, to 1-2 mm or less, but practice shows that this is economically unprofitable, therefore, at crushing and processing plants, crushing is carried out in several stages, using the most suitable type of crusher for each stage: 1) coarse crushing from 1500 to 250 mm; 2) average crushing from 250 to 50 mm; 3) fine crushing from 50 to 5-6 mm; 4) grinding up to 0.04 mm.

Most crushers used in industry work on the principle of crushing pieces of ore between two steel surfaces approaching each other. Ores are crushed using jaw crushers (coarse and medium crushing), cone crushers (coarse, medium and fine crushing), roller and hammer crushers(medium and fine crushing).

jaw crusher(Fig. 1, a) consists of three main parts: - a fixed steel vertical plate, called a fixed cheek, - a movable cheek, suspended in the upper part, - a crank mechanism that imparts oscillatory movements to the movable cheek. Material is loaded into the crusher from above. When the cheeks come together, the pieces are destroyed. When the movable cheek moves away from the fixed jaw, the crushed pieces fall under the action of their own weight and exit the crusher through the discharge opening.

Rice. 1 Crushers: a - jaw; b - conical; in - hammer; g - roll

cone crushers work on the same principle as the jaw ones, although they differ significantly from the latter in design. A cone crusher (Fig. 1, b) consists of a fixed cone, a movable cone suspended in the upper part. The axis of the movable cone bottom enters eccentrically into a rotating vertical glass, due to which the movable cone makes circular movements inside the large one. When the movable cone approaches some part of the fixed cone, the pieces are crushed, filling the space between the cones in this part of the crusher, while in the diametrically opposite part of the crusher, where the surfaces of the cones are removed to the maximum distance, the crushed ore is unloaded. Unlike jaw crushers, cone crushers have no idling, due to which the productivity of the latter is several times higher. For medium and fine crushing, short-cone crushers are used, operating on the same principle as cone crushers, but slightly different in design.

IN roller crusher ore crushing occurs between two parallel steel rolls located horizontally, rotating towards each other (Fig. 1, c).

For crushing brittle rocks of low and medium strength (limestone, bauxite, coal, etc.) hammer crushers, the main part of which (Fig. 1, d) is a rotor rotating at high speed (500-1000 rpm) - a shaft with steel plates-hammers fixed on it. Crushing of material in crushers of this type occurs under the action of numerous hammer blows on falling pieces of material.

Usually used for crushing ores. ball or rod mills, which are cylindrical drums rotating around a horizontal axis with a diameter of 3-4 m, in which, together with pieces of ore, there are steel balls or long rods. As a result of rotation with a relatively high frequency (~20 min -1), the balls or rods, having reached a certain height, roll down or fall down, carrying out the grinding of ore pieces between the balls or between the balls and the surface of the drum. The mills operate continuously - ore is loaded through one hollow trunnion, and unloaded through another. As a rule, grinding is carried out in an aqueous medium, due to which not only dust emission is eliminated, but also the productivity of the mills is increased. During the grinding process, automatic sorting of particles by size takes place - small ones pass into a suspended state and are taken out of the mill in the form of pulp (a mixture of ore particles with water), while larger ones that cannot be in a suspended state remain in the mill and are crushed further.