Processing of copper ore. Copper ore processing complex
Copper ore has a different composition, which affects its quality characteristics and determines the choice of method for enriching the feedstock. The composition of the rock may be dominated by sulfides, oxidized copper, or a mixed amount of components may be present. At the same time, for ore mined in the Russian Federation, the flotation enrichment method is used.
Processing of disseminated and continuous copper sulfide ore, which contains no more than a quarter of oxidized copper, is carried out in Russia at processing plants:
- Balkhash;
- Dzhezkazgan;
- Sredneuralskaya;
- Krasnouralskaya.
The technology for processing raw materials is selected in accordance with the type of source material.
Working with disseminated ores involves extracting sulfides from the rock and moving them into depleted concentrates using chemical compounds: blowing agents, hydrocarbons and xanthate. The primary method used is fairly coarse grinding of the rock. After processing, the lean concentrate and middlings undergo an additional process of grinding and cleaning. During processing, copper is freed from intergrowths with pyrite, quartz and other minerals.
The homogeneity of the porphyritic ore supplied for processing makes it possible to flotate it at large processing plants. High level productivity allows you to reduce the cost of the enrichment procedure, as well as accept ore with a low copper content (up to 0.5%) for processing.
Flotation process diagrams
The flotation process itself is built according to several basic schemes, each of which differs in both the level of complexity and cost. The simplest (cheapest) scheme involves switching to an open ore processing cycle (at the 3rd stage of crushing), grinding the ore within one stage, as well as carrying out a subsequent additional grinding procedure to obtain a result of 0.074 mm.
During the flotation process, the pyrite contained in the ore is subjected to depression, leaving in the concentrates a sufficient level of sulfur necessary for the subsequent production of slag (matte). To carry out 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-containing minerals (sulfates) and pyrite. Copper sulfides form thin films (covellite) on pyrite, and due to the complexity chemical composition the floatability of such ore is somewhat reduced. An effective beneficiation process requires careful grinding of the rock to facilitate the release of copper sulfides. It is noteworthy that in a number of cases, thorough grinding is not economically feasible. We are talking about situations where pyrite concentrate, subjected to a roasting process, is used in blast furnace to extract precious metals.
Flotation is carried out by creating an alkaline environment of high concentration. The following are used in the process in specified proportions:
- lime;
- xanthate;
- fleetoil.
The procedure is quite energy-intensive (up to 35 kW h/t), which increases production costs.
The ore grinding process is also complex. As part of its implementation, multi-stage and multi-stage processing of the source material is provided.
Intermediate ore beneficiation
Processing of ore with a sulfide content of up to 50% is similar in technology to the processing of solid sulfide ore. The only difference is the degree of its grinding. Material of a coarser fraction is accepted for processing. In addition, the separation of pyrite does not require the preparation of an environment with such a high alkali content.
At the Pyshminsky concentrating plant, collective flotation followed by selective processing is practiced. The technology makes it possible to use 0.6% ore to obtain 27% copper concentrate with subsequent extraction of over 91% copper. Work is carried out in an alkaline environment with different levels intensity at each stage. The processing scheme allows reducing the consumption of reagents.
Technology of combined enrichment methods
It is worth noting that ore with a low content of clay and iron hydroxide impurities lends itself better to the beneficiation process. The flotation method allows you 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 use is relevant for the Russian industry, since the amount of refractory ore makes up a significant part of the total production of copper-bearing ore.
The technological process involves crushing raw materials (fraction size up to 6 mm) followed by immersing the material in a sulfuric acid solution. 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 flotated. The copper solution is combined with the slurry and then subjected to leaching, cementation and flotation.
In work using the Mostovich method, sulfuric acid is used, as well as precipitating components. The use of technology turns out to be more expensive compared to standard flotation.
The use of Mostovich's alternative scheme, which involves the recovery of copper from the oxide with flotation after crushing the ore subjected to heat treatment, allows to reduce costs somewhat. The technology can be made cheaper by using 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 with primary sulfide copper-zinc ore is somewhat simpler, then the situation when exchange reactions began with the ore already in the deposit itself can complicate the enrichment process. Selective flotation may not be possible when dissolved copper and cavellin films are present in the ore. Most often, this picture occurs with ore mined from the upper horizons.
In the beneficiation of Ural ore, which is quite poor in copper and zinc content, both selective and collective flotation technologies are effectively used. At the same time, the method of combined ore processing and the scheme of collective selective enrichment are increasingly used at leading enterprises in the industry.
Copper ore processing plant in mining, beneficiation, smelting, refining and casting
Crushing and screening complex for processing copper ore
Copper ore processing plant is a crushing plant specially designed for crushing copper ore. When the copper ore comes out of the ground, it is loaded into a 300-ton truck to transport the crusher. The complete copper crushing plant includes jaw crushers like main crusher, impact crusher and cone crusher. Once crushed, the copper ore must be screened by size by screening machine and distributing the classified ore to a series of conveyors, for transportation to the mill for further processing.
Copper ore processing complex
The process of extracting copper from copper ore varies depending on the type of ore and the required purity of the final product. Each process consists of several steps in which unwanted materials are physically or chemically removed and the copper concentration is gradually increased.
Firstly, the copper ore from the open pit is crushed, loaded and transported to the primary crusher. The ore is then crushed and screened, with fine sulfide ore (< 0.5 мм) собирается пенной флотации клеток для восстановления меди. Крупные частицы руды идет в кучного выщелачивания, где меди подвергается разбавленного раствора серной кислоты, чтобы растворить медь.
The alkaline solution containing dissolved copper is then subjected to a process called solvent extraction (SX). The SX process concentrates and purifies the copper leach solution, so the copper can be recovered with high efficiency electric current through cell electrolysis. It does this by adding a chemical to the SX tanks that selectively binds to and extracts the copper, easily separating it from the copper, recovering as much of the reagent as possible for reuse.
A concentrated solution of copper is dissolved in sulfuric acid and sent to electrolytic cells to restore copper plates. From copper cathodes, it is made into wires, devices, etc.
SBM can offer types of crushers, screening and grinding machine, copper ore flotation plant, processing plant in USA, Zambia, Canada, Australia, Kenya, South Africa, Papua New Guinea and Congo.
Copper can be produced as a main product or as a co-product with gold, lead, zinc and silver. It is mined in the Northern and Southern Hemispheres and primarily consumed in the Northern Hemisphere with the United States as the main producer and consumer.
A copper processing plant processes copper from metal ore and copper scrap. The leading consumers of copper are wire mills and copper mills, which use copper to produce copper wire etc. End uses of copper include Construction 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 attaches the copper, causing it to float at the top of the slurry.
Crushing complex for copper ore
Large raw copper ore is fed into the copper ore jaw crusher, evenly and gradually, by vibrating feeder through the copper ore primary crushing hopper. Once separated, the crushed pieces of copper ore can meet the standard and will be taken as the final product.
After the first crushing, the material will be transferred to the copper ore impact crusher, copper ore cone crusher, secondary crushing conveyor. Then the crushed materials are transferred to the vibrating sieve for separation. The final production of copper ore will be taken away, and 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 rated according to customers' requirement. We can also equip ash removal systems to protect the environment.
Mill complex for copper ore
After primary and recycling in the copper ore production line, it can enter the next stage to grind the copper ore. The final copper ore powder produced by Zenith copper ore milling equipment typically contains less than 1% copper, while sulfide ores have moved to the beneficiation stage, while oxidized ores are used for leach 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 effective 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 unloading material. Ball Mill is a crucial equipment for grinding after crushed materials. It is an effective tool for grinding i various materials into powder.
It can also use mills such as MTW European type trapezoidal mills, XZM ultrafine grinding mills, MCF coarse powder grinding mills, vertical mills, etc.
Machines used for crushing - crushers - can reduce the size of pieces to 5-6 mm. Finer crushing is called grinding and is carried out in mills.
In most cases, crushing together with grinding are preparatory operations before ore beneficiation. Although it is possible to crush in one unit from 1500 mm, for example, to 1-2 mm or less, 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 to 0.04 mm.
Most crushers used in industry operate on the principle of crushing pieces of ore between two steel surfaces approaching each other. For crushing ores, jaw crushers (coarse and medium crushing), cone crushers (coarse, medium and fine crushing), roller and hammer crushers (medium and fine crushing) are used.
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. The material is loaded into the crusher from above. When the cheeks come together, the pieces break apart. When the moving jaw moves away from the fixed one, the crushed pieces fall under the influence of their own weight and exit the crusher through the discharge hole.
Rice. 1 Crushers: a – jaw; b – conical; c – hammer; g – roller
Cone crushers They work on the same principle as cheek ones, although they differ significantly from the latter in design. A cone crusher (Fig. 1, b) consists of a fixed cone and a movable cone suspended in the upper part. The axis of the movable cone with its lower part enters eccentrically into the 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 one, 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, 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 roll crusher crushing of ore occurs between two horizontal steel parallel rolls 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-shaft rotating at high speed (500-1000 rpm) with steel hammer plates attached to it. Crushing of material in crushers of this type occurs under the influence of numerous hammer blows on falling pieces of material.
Commonly used for grinding ores ball or rod mills, which are cylindrical drums with a diameter of 3-4 m rotating around a horizontal axis, in which steel balls or long rods are located along with pieces of ore. As a result of rotation at a relatively high frequency (~20 min -1), the balls or rods, having reached a certain height, roll or fall down, grinding pieces of ore between the balls or between the balls and the surface of the drum. The mills operate in a continuous mode - loading with ore occurs through one hollow axle, and unloading through another. Typically, grinding is carried out in aquatic environment, due to which not only dust emissions are eliminated, but also the productivity of the mills is increased. During the grinding process there is automatic sorting particles by size - small ones become suspended and in the form of a pulp (a mixture of ore particles with water) are removed from the mill, and larger ones, which cannot be suspended, remain in the mill and are crushed further.
Owners of patent RU 2418872:
The invention relates to copper metallurgy, namely to methods for processing mixed (sulfide-oxidized) copper ores, as well as middlings, tailings and slag containing oxidized and sulfide copper minerals. A method for processing mixed copper ores involves crushing and grinding the ore. Then the crushed ore is leached with a sulfuric acid solution with a concentration of 10-40 g/dm 3 with stirring, solid phase content 10-70%, duration 10-60 minutes. After leaching, the ore leaching cake is dewatered and washed. Then the liquid phase of ore leaching is combined with washing waters and the combined copper-containing solution is freed from solid suspensions. Copper is extracted from a copper-containing solution to produce copper cathode. From the leaching cake, copper minerals are flotated at a pH value of 2.0-6.0 to obtain a flotation concentrate. The technical result consists in increasing the extraction of copper from ore into commercial products, reducing the consumption of reagents for flotation, increasing the flotation speed, and reducing grinding costs. 7 salary files, 1 ill., 1 table.
The invention relates to copper metallurgy, namely to methods for processing mixed (sulfide-oxidized) copper ores, as well as middling products, tailings and slags containing oxidized and sulfide copper minerals, and can also be used for processing mineral products of other non-ferrous metals.
Processing of copper ores is carried out using leaching or flotation concentration, as well as using combined technologies. World practice in processing copper ores shows that the degree of their oxidation is the main factor influencing the choice of technological schemes and determining the technological and technical-economic indicators of ore processing.
For recycling mixed ores technological schemes have been developed and applied that differ in the methods used for extracting metal from ore, methods for extracting metal from leaching solutions, the sequence of extraction methods, methods for separating solid and liquid phases, organizing phase flows and rules for the layout of operations. The set and sequence of methods in the technological scheme is determined in each specific case and depends, first of all, on the mineral forms of copper in the ore, the copper content in the ore, the composition and nature of the host minerals and ore rocks.
There is a known method for extracting copper, which consists of dry crushing of ore to a particle size of 2, 4, 6 mm, leaching with classification, subsequent flotation of the granular part of the ore and precipitation of the sludge fraction of copper concentrate with sponge iron from the sludge part of the ore (AS USSR N 45572, B03B 7/00, 01/31/36).
The disadvantage of this method is the low extraction of copper and the quality of the copper product, which requires additional operations to improve.
There is a known method for obtaining metals, which consists in grinding the source material to a fraction size exceeding the fraction size required for flotation, leaching with sulfuric acid in the presence of iron belongings, followed by sending solid residues for flotation of copper deposited on the iron belongings (DE 2602849 B1, C22B 3/02 , 12/30/80).
A similar method for processing refractory oxidized copper ores by Professor Mostovich is known (Mitrofanov S.I. et al. Combined processes for processing non-ferrous metal ores, M., Nedra, 1984, p. 50), which consists of leaching oxidized copper minerals with acid, cementing copper from solution iron powder, flotation of cement copper from an acidic solution to obtain copper concentrate. The method is used for processing refractory oxidized ores of the Kalmakir deposit at the Almalyk mining and metallurgical plant.
The disadvantages of these methods are the high cost of implementation due to the use of iron belongings, which reacts with acid, thereby increasing the consumption of both sulfuric acid and iron belongings; low copper recovery by cementation with iron waste and flotation of cement particles. The method is not applicable for the processing of mixed ores and flotation separation of sulfide copper minerals.
The closest to the claimed method in technical essence is the method of processing sulfide-oxidized copper ores (RF Patent No. 2337159 priority 04/16/2007), including crushing and grinding of ore to a particle size of 1.0-4.0 mm, leaching for 0.5- 2.0 hours of crushed ore with a sulfuric acid solution with a concentration of 10-40 g/dm 3 with stirring, solid phase content of 50-70%, dehydration and washing of the leaching cake, its grinding, combining the liquid phase of ore leaching with the washing waters of the ore leaching cake, release from solid suspensions and extraction of copper from a copper-containing solution to obtain cathode copper and flotation of copper minerals from crushed leaching cake in an alkaline environment with a reagent-regulator to obtain a flotation concentrate.
The disadvantages of this method are the high consumption of reagents-regulators of the environment for flotation in an alkaline environment, insufficiently high extraction of copper during flotation due to oxide copper minerals coming after leaching of large particles, shielding of copper minerals with a reagent-regulator of the environment, high consumption of collectors for flotation.
The invention achieves a technical result consisting in increasing the extraction of copper from ore into commercial products, reducing the consumption of reagents for flotation, increasing the flotation speed, and reducing grinding costs.
The specified technical result is achieved by a method of processing mixed copper ores, including crushing and grinding of ore, leaching of crushed ore with a solution of sulfuric acid with a concentration of 10-40 g/dm 3 with stirring, solid phase content of 10-70%, lasting 10-60 minutes, dehydration and washing ore leaching cake, combining the liquid phase of ore leaching with the leaching cake wash waters, releasing the combined copper-containing solution from solid suspensions, extracting copper from the copper-containing solution to produce cathode copper and flotation of copper minerals from the leaching cake at a pH value of 2.0-6.0 s obtaining flotation concentrate.
Particular cases of using the invention are characterized by the fact that ore is crushed to a component size ranging from 50-100% class minus 0.1 mm to 50-70% class minus 0.074 mm.
Also, washing the leaching cake is carried out simultaneously with its dewatering by filtration.
In addition, the combined copper-containing solution is freed from solid suspensions by clarification.
Preferably, flotation is carried out using several of the following collectors: xanthate, sodium diethyldithiocarbamate, sodium dithiophosphate, aeroflot, pine oil.
Copper is also extracted from a copper-containing solution by liquid extraction and electrolysis.
In addition, the extraction raffinate generated during liquid-liquid extraction is used for ore leaching and for washing the leach cake.
And also the spent electrolyte formed during electrolysis is used for leaching of ore and for washing the leaching cake.
The speed and efficiency of leaching of copper minerals from ore depends on the size of the ore particles: the smaller the particle size, the more accessible the minerals are to leaching and dissolve faster and to a greater extent. For leaching, the ore is crushed to a particle size slightly larger than for flotation concentration, i.e. from 50-100% class minus 0.1 mm, to 50-70% class minus 0.074 mm, since after leaching the particle size decreases. The content of the size class when grinding ore depends on the mineral composition of the ore, in particular on the degree of oxidation of copper minerals.
After leaching the ore, flotation of copper minerals is carried out, the effectiveness of which also depends on the size of the particles - large particles and the smallest particles - sludge - float poorly. When leaching crushed ore, the slurry particles are completely leached, and the largest ones are reduced in size, as a result, the particle size without additional grinding corresponds to the size of the material required for effective flotation of mineral particles.
Stirring during leaching of crushed ore ensures an increase in the rate of mass transfer physical and chemical processes, while the extraction of copper into the solution increases and the duration of the process decreases.
Leaching of crushed ore is effectively carried out at a solid phase content of 10 to 70%. Increasing the ore content during leaching to 70% allows you to increase the productivity of the process, the concentration of sulfuric acid, creates conditions for friction between particles and their grinding, and also allows you to reduce the volume of leaching apparatus. Leaching at high ore grades results in high copper concentrations in solution, which reduces driving force mineral dissolution and leaching rate compared to low solids leaching.
Leaching ore with a particle size of minus 0.1-0.074 mm with a sulfuric acid solution with a concentration of 10-40 g/dm 3 for 10-60 minutes allows for high extraction of copper from oxidized minerals and secondary copper sulfides. The rate of dissolution of oxidized copper minerals in a solution of sulfuric acid with a concentration of 10-40 g/dm 3 is high. After leaching of crushed mixed copper ore for 5-10 minutes, the content of difficult-to-float oxidized minerals in the ore is significantly reduced and is less than 30%, thus it becomes sulfide grade. Recovery of copper minerals remaining in the leach cake can be accomplished by sulfide mineral flotation. As a result of sulfuric acid leaching of crushed mixed copper ore, oxidized copper minerals and up to 60% secondary copper sulfides are almost completely dissolved. The copper content in the leaching cake and the load on flotation enrichment of the leaching cake are significantly reduced and, accordingly, the consumption of flotation reagents - collectors - is reduced.
Preliminary sulfuric acid treatment of sulfide-oxidized copper ores allows not only to remove difficult-to-float oxidized copper minerals, but also to clean the surface of sulfide minerals from iron oxides and hydroxides, and to change the composition of the surface layer in such a way that the flotability of copper minerals increases. Using X-ray photoelectron spectroscopy, it was established that as a result of sulfuric acid treatment of copper sulfides, a change occurs in the elemental and phase composition of the surface of minerals, affecting their flotation behavior - the sulfur content increases by 1.44 times, copper by 4 times, and the iron content decreases by 1.6 times. The ratio of sulfur phases on the surface after sulfuric acid treatment of secondary copper sulfides changes significantly: the proportion of elemental sulfur increases from 10 to 24% of total sulfur, the proportion of sulfate sulfur - from 14 to 25% (see drawing: spectra of sulfur S2p (type of hybridization of electronic orbitals, characterized by a certain binding energy) surface of copper sulfides, A - without treatment, B - after sulfuric acid treatment, 1 and 2 - sulfur in sulfides, 3 - elemental sulfur, 4, 5 - sulfur in sulfates). Taking into account the increase in total sulfur on the surface of minerals, the content of elemental sulfur increases by 3.5 times, sulfate sulfur by 2.6 times. Studies of the surface composition also show that as a result of sulfuric acid treatment, the content of iron oxide Fe 2 O 3 on the surface decreases and the content of iron sulfate increases, the content of copper sulfide Cu 2 S decreases and the content of copper sulfate increases.
Thus, when leaching crushed mixed copper ore, the composition of the surface of copper sulfide minerals changes, affecting their flotation qualities, in particular:
The content of elemental sulfur on the surface of copper sulfide minerals, which has hydrophobic properties, increases, which reduces the consumption of collectors for flotation of copper sulfide minerals;
The surface of copper minerals is cleared of iron oxides and hydroxides, which shield the surface of the minerals, therefore the interaction of minerals with the collector is reduced.
For further processing of leaching products, the leach cake is dewatered, which can be combined with washing the leach cake, for example, on belt filters, to remove copper contained in the cake moisture. A variety of filtration equipment, such as filter centrifuges and vacuum belt filters, as well as precipitation centrifuges, etc., are used to dewater and wash the ore leaching cake.
The ore leaching solution and the wash waters of the ore leaching cake to extract the copper contained in them are combined and freed from solid suspensions, since they worsen the conditions for copper extraction and reduce the quality of the resulting copper cathode, especially when using the liquid extraction process with an organic extractant. Removal of suspended matter can be carried out in the most in a simple way- clarification, as well as additional filtration.
Copper is extracted from the clarified copper-containing solution of ore leaching and washing of the leaching cake to produce copper cathode. A modern method for extracting copper from solutions is the method of liquid extraction with an organic cation-exchange extractant. Using this method allows you to selectively extract and concentrate copper in solution. After re-extraction of copper from the organic extractant, electroextraction is performed to produce cathode copper.
During liquid extraction of copper from sulfuric acid solutions with an organic extractant, an extraction raffinate is formed, which contains 30-50 g/dm 3 of sulfuric acid and 2.0-5.0 g/dm 3 of copper. To reduce acid consumption for leaching and copper losses, as well as rational water circulation in the technological scheme, the extraction raffinate is used for leaching and for washing the leaching cake. In this case, the concentration of sulfuric acid in the residual moisture of the leach cake increases.
During the electrolysis of copper, a spent electrolyte is formed from copper-containing solutions purified from impurities, such as iron, and concentrated during liquid extraction, with a concentration of 150-180 g/dm 3 of sulfuric acid and 25-40 g/dm 3 of copper. Just like the extraction raffinate, the use of spent electrolyte for leaching and washing the leaching cake makes it possible to reduce the consumption of fresh acid for leaching, the loss of copper, and rationally use the aqueous phase in the technological scheme. When using spent electrolyte for washing, the concentration of sulfuric acid in the residual moisture of the leach cake increases.
Grinding after leaching for flotation separation of copper minerals is not required, since during the leaching process the particles decrease in size and the leach cake size corresponds to the flotation class 60-95% minus 0.074 mm.
In Russia, an alkaline environment is used for flotation enrichment of copper minerals, which is determined by the predominant use of xanthate as collectors, which are known to decompose under acidic conditions, and, in some cases, by the need for pyrite depression. To regulate the environment during alkaline flotation, industry most often uses lime milk as the cheapest reagent that allows the pH to be increased to highly alkaline values. Calcium entering the flotation pulp with lime milk to some extent screens the surface of minerals, which reduces their floatability, increases the yield of enrichment products and reduces their quality.
When processing mixed copper ores from the Udokan deposit, the crushed ore after sulfuric acid treatment is washed from copper ions with acidic extraction raffinate, spent electrolyte and water. As a result, the moisture in the leach cakes is acidic. Subsequent flotation of copper minerals under alkaline conditions requires washing with a large flow of water and neutralization with a large flow of lime, which increases processing costs. Therefore, it is advisable to carry out flotation enrichment of sulfide copper minerals after sulfuric acid leaching in an acidic environment, at a pH value of 2.0-6.0, to obtain copper concentrate and waste tailings.
Research has shown that in the main flotation of copper minerals from sulfuric acid leaching cakes, with a decrease in pH value, the copper content in the main flotation concentrate gradually increases from 5.44% (pH 9) to 10.7% (pH 2) with a decrease in yield from 21% to 10.71% and a decrease in recovery from 92% to 85% (Table 1).
| Table 1 | |||||
| An example of enrichment of sulfuric acid leaching cakes of copper ore from the Udokan deposit at different pH values | |||||
| pH | Products | Exit | Copper content,% | Copper recovery, % | |
| G | % | ||||
| 2 | Main flotation concentrate | 19,44 | 10,71 | 10,77 | 85,07 |
| 38,88 | 21,42 | 0,66 | 10,43 | ||
| Tails | 123,18 | 67,87 | 0.09 | 4,5 | |
| Source Ore | 181,50 | 100,00 | 1,356 | 100,00 | |
| 4 | Main flotation concentrate | 24,50 | 12,93 | 8,90 | 87,48 |
| Control flotation concentrate | 34,80 | 18,36 | 0,56 | 7,82 | |
| Tails | 130,20 | 68,71 | 0,09 | 4,70 | |
| Source Ore | 189,50 | 100,00 | 1,32 | 100,00 | |
| 5 | Main flotation concentrate | 32,20 | 16,51 | 8,10 | 92,25 |
| Control flotation concentrate | 17,70 | 9,08 | 0,50 | 3,13 | |
| Tails | 145,10 | 74,41 | 0,09 | 4,62 | |
| Source Ore | 195,00 | 100,00 | 1,45 | 100,00 | |
| 6 | Main flotation concentrate | 36,70 | 18,82 | 7,12 | 92,89 |
| Control flotation concentrate | 16,00 | 8,21 | 0,45 | 2,56 | |
| Tails | 142,30 | 72,97 | 0,09 | 4,55 | |
| Source Ore | 195,00 | 100,00 | 1,44 | 100,00 | |
| 7 | Main flotation concentrate | 35,80 | 19,02 | 6,80 | 92,40 |
| Control flotation concentrate | 15,40 | 8,18 | 0,41 | 2,40 | |
| Tails | 137,00 | 72,79 | 0,10 | 5,20 | |
| Source Ore | 188,20 | 100,00 | 1,40 | 100,00 | |
| 8 | Main flotation concentrate | 37,60 | 19,17 | 6,44 | 92,39 |
| Control flotation concentrate | 14,60 | 7,45 | 0,38 | 2,12 | |
| Tails | 143,90 | 73,38 | 0,10 | 5,49 | |
| Source Ore | 196,10 | 100,00 | 1,34 | 100,00 | |
| 9 | Main flotation concentrate | 42,70 | 21,46 | 5,44 | 92,26 |
| Control flotation concentrate | 14,30 | 7,19 | 0,37 | 2,10 | |
| Tails | 142,00 | 71,36 | 0,10 | 5,64 | |
| Source Ore | 199,00 | 100,00 | 1,27 | 100,00 |
During control flotation, the lower the pH value, the greater the copper content in the concentrate, the yield and recovery. The yield of the control flotation concentrate in an acidic environment is high (18.36%), with an increase in the pH value the yield of this concentrate decreases to 7%. The recovery of copper in the total concentrate of the main and control flotation is almost the same over the entire range of pH values studied and is about 95%. Flotation recovery at lower pH is higher compared to copper recovery at higher pH. high value pH, which is explained by the high yield in concentrates under acidic flotation conditions.
After sulfuric acid treatment of ore, the flotation speed of sulfide copper minerals increases, the time of main and control flotation is only 5 minutes, in contrast to the ore flotation time of 15-20 minutes. The rate of flotation of copper sulfides is significantly greater than the rate of xanthate decomposition at low pH values. The best results of flotation enrichment are achieved by using several collectors from the series potassium butyl xanthate, sodium dithiophosphate, sodium diethyldithiocarbamate (DEDTC), aeroflot, pine oil.
Based on the residual concentration of xanthate after interaction with copper sulfides, it was experimentally determined that 1.8÷2.6 times less xanthate is sorbed on the surface of minerals subjected to sulfuric acid treatment than on the surface without treatment. This experimental fact is consistent with the data on the increase in the content of elemental sulfur on the surface of copper sulfides after sulfuric acid treatment, which, as is known, increases its hydrophobicity. Studies of foam flotation of secondary copper sulfides have shown (abstract of the dissertation “Physico-chemical foundations of combined technology for processing copper ores of the Udokan deposit” by L.N. Krylov”) that sulfuric acid treatment leads to an increase in the extraction of copper into concentrate by 7.2÷10.1% , solid phase yield by 3.3÷5.5% and copper content in the concentrate by 0.9÷3.7%.
The invention is illustrated by examples of method implementation:
Mixed copper ore of the Udokan deposit, containing 2.1% copper, of which 46.2% is in oxidized copper minerals, was crushed, ground to a size of 90% minus 0.1 mm, leached in a stirred vat at a solid phase content of 20% , the initial concentration of sulfuric acid is 20 g/dm 3 with maintaining the concentration of sulfuric acid at the level of 10 g/dm 3 for 30 minutes. Extraction raffinate and spent electrolyte were used for leaching. The leach cake was dewatered on a vacuum filter and washed on a belt filter with extraction raffinate and water.
Flotation enrichment of sulfuric acid leaching cake was carried out at pH 5.0 using potassium butyl xanthate and sodium diethyldithiocarbamate (DEDTC) as collectors in an amount 16% less than for flotation of crushed copper ore leaching cake with a particle size of 1-4 mm. As a result of flotation enrichment, the extraction of copper into the total sulfide copper concentrate was 95.1%. Lime was not used for flotation enrichment, which is consumed in quantities of up to 1200 g/t of ore during alkaline flotation of the leaching cake.
The liquid phase of leaching and wash water were combined and clarified. Extraction of copper from solutions was carried out with a solution of the organic extractant LIX 984N; copper cathode was obtained by electrolysis of copper from a copper-containing acid solution. The end-to-end extraction of copper from ore using the method was 91.4%.
Copper ore of the Chiney deposit, containing 1.4% copper, of which 54.5% is in oxidized copper minerals, was crushed and crushed to a size of 50% class minus 0.074 mm, leached in a stirring vat at a solid phase content of 60%, initial concentration sulfuric acid 40 g/dm 3 using waste electrolyte. The leaching pulp was dehydrated on a vacuum filter and washed on a belt filter, first with the spent electrolyte and extraction raffinate, then with water. The leaching cake without regrinding was enriched by flotation at pH 3.0 using xanthate and aeroflot at a flow rate (total consumption 200 g/t) lower than during ore flotation (collector consumption 350-400 g/t). Copper recovery in copper sulfide concentrate was 94.6%.
The liquid phase of the leach and the leach cake wash water were combined and clarified. Extraction of copper from solutions was carried out with a solution of the organic extractant LIX; cathode copper was obtained by electrical extraction of copper from a copper-containing acid solution. The end-to-end recovery of copper from ore into marketable products was 90.3%.
1. A method for processing mixed copper ores, including crushing and grinding of ore, leaching of crushed ore with a sulfuric acid solution with a concentration of 10-40 g/dm 3 with stirring, solid phase content of 10-70%, duration 10-60 minutes, dehydration and washing of the cake ore leaching, combining the liquid phase of ore leaching with the wash waters of the leaching cake, releasing the combined copper-containing solution from solid suspensions, extracting copper from the copper-containing solution to obtain cathode copper and flotation of copper minerals from the leaching cake at a pH value of 2.0-6.0 to obtain flotation concentrate.
2. The method according to claim 1, in which the ore is crushed to a size ranging from 50-100% of the class minus 0.1 mm to 50-70% of the class minus 0.074 mm.
3. The method according to claim 1, in which the leaching cake is washed simultaneously with its dewatering by filtration.
4. The method according to claim 1, in which the combined copper-containing solution is freed from solid suspensions by clarification.
5. The method according to claim 1, in which the flotation is carried out using several of the following collectors: xanthate, sodium diethyldithiocarbamate, sodium dithiophosphate, aeroflot, pine oil.
6. The method according to claim 1, in which the extraction of copper from a copper-containing solution is carried out by liquid extraction and electrolysis.
7. The method according to claim 6, in which the extraction raffinate formed by liquid extraction is used for leaching the ore and for washing the leach cake.
8. The method according to claim 6, in which the spent electrolyte formed during electrolysis is used for leaching of ore and for washing the leach cake.
The invention relates to copper metallurgy, namely to methods for processing mixed copper ores, as well as middlings, tailings and slags containing oxidized and sulfide copper minerals
