RU2418872C2 - Procedure for processing mixed copper ore - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure for processing mixed copper ore consists in ore crushing and crumbling. Further, crumbled ore is leached with solution of sulphuric acid of concentration 10-40 g/dm³ and mixed during 10-60 min at contents of solid phase 10-70 %. Upon leaching cake of ore leaching is dehydrated and flushed. Further, flush water is added to a liquid phase of ore leaching and solid suspensions are released from joined copper containing solution. Copper is extracted from copper containing solution and there is produced cathode copper. Flotation of copper minerals from leaching cake is performed at value of pH 2.0-6.0 and there is produced flotation concentrate.

EFFECT: raised extraction of copper into commodity products, reduced consumption of reagents for flotation, increased rate of flotation, and reduced expenditures for crumbling.

8 cl, 1 dwg, 2 ex

Description

The invention relates to copper metallurgy, and in particular to methods of processing mixed (sulfide-oxidized) copper ores, as well as intermediate products, tails and slags containing oxidized and sulfide minerals of copper, 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 processing, as well as using combined technologies. World practice of processing copper ores shows that the degree of oxidation is the main factor affecting the choice of technological schemes and determining technological and technical and economic indicators of ore processing.

For the processing of mixed ores, technological schemes have been developed and are applied, which 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, organization of phase flows and the rules for the arrangement 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.

A known method for the extraction of copper, which consists in dry crushing ore to a particle size of 2, 4, 6 mm, leaching with classification, subsequent flotation of the granular part of the ore and sedimentation of the slurry fraction of copper concentrate with sponge iron from the slurry part of the ore (A.S. USSR N 45572, V03B 7/00, 01/31/36).

The disadvantage of this method is the low extraction of copper and the quality of the copper product, to increase which additional operations are required.

There is a method of producing metals, which consists in grinding the starting material to a particle size larger than the fraction needed for flotation, leaching with sulfuric acid in the presence of iron skar, followed by the direction of solid residues for flotation of copper deposited on iron skar (DE 2602849 B1, С22В 3/02 , 12/30/80).

A similar method is known for processing refractory oxidized copper ores of Professor Mostovich (Mitrofanov S.I. et al. Combined processes for processing non-ferrous metal ores, M., Nedra, 1984, p. 50), which consists in leaching oxidized copper minerals with acid, cementing copper from solution iron powder, flotation of cement copper from an acid solution to obtain a copper concentrate. The method is used for processing refractory oxidized ores of the Kalmakir deposit at the Almalyk mining and smelting plant.

The disadvantages of these methods is the high cost of implementation in connection with the use of iron belongings, which reacts with acid, while increasing the consumption of both sulfuric acid and iron belongings; low copper recovery by fermentation with iron stock and flotation of cement particles. The method is not applicable for the processing of mixed ores and flotation separation of sulfide copper minerals.

Closest to the claimed method in technical essence is a 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 solution of sulfuric acid with a concentration of 10-40 g / dm ³ with stirring, the solids content of 50-70%, dehydration and washing of the leach cake, its grinding, combining the liquid phase of the leaching of ore with the washing water of the ore leaching cake, releasing from solid to stars and extracting copper from a copper-containing solution to obtain cathode copper and flotation of copper minerals from crushed leaching cake in an alkaline medium with a reagent-regulator to obtain a flotation concentrate.

The disadvantages of the method are the high consumption of reagents-regulators of the environment for flotation in an alkaline environment, the insufficiently high copper recovery during flotation due to oxide copper minerals entering after leaching of large particles, the screening of minerals of copper by the reagent-regulator of the medium, and the high consumption of collectors for flotation.

The invention achieves the technical result, which consists in increasing the extraction of copper from ore into commercial products, reducing the consumption of reagents for flotation, increasing the speed of flotation, reducing the cost of grinding.

The specified technical result is achieved by a method of processing mixed copper ores, including crushing and grinding ore, leaching the crushed ore with a solution of sulfuric acid with a concentration of 10-40 g / dm ³ with stirring, the solids content of 10-70%, lasting 10-60 minutes, dehydration and washing ore leaching cake, combining the liquid ore leaching phase with wash water, leaching cake, releasing the combined copper-containing solution from solid suspensions, extracting copper from the copper-containing solution with the preparation of cathode copper and flotation of copper minerals from the leach cake at a pH of 2.0-6.0 to obtain a flotation concentrate.

Particular cases of using the invention are characterized by the fact that ore grinding is carried out to a particle size of from 50-100% class minus 0.1 mm to 50-70% class minus 0.074 mm.

Also leaching cake leaching is carried out simultaneously with its dehydration 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.

Also, the extraction of copper from a copper-containing solution is carried out by liquid extraction and electrolysis.

In addition, the extraction raffinate resulting from liquid extraction is used to leach ore and to wash the leach cake.

And also the spent electrolyte formed during electrolysis is used to leach ore and to flush the leach cake.

The speed and efficiency of leaching copper minerals from ore depends on the particle size of the ore: the smaller the particle size, the minerals are more accessible for leaching, faster and more dissolved. For leaching, ore is crushed to a larger size than for flotation, i.e. from 50-100% of the class minus 0.1 mm, to 50-70% of the 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 oxidation state of copper minerals.

After ore leaching, copper minerals are flotated, the effectiveness of which also depends on the particle size - large particles are poorly floated and the smallest particles - sludge. When the crushed ore is leached, the sludge particles are completely leached, and the largest are reduced in size, as a result, the particle size without additional grinding corresponds to the material size required for efficient flotation of mineral particles.

Stirring during leaching of the crushed ore provides an increase in the rate of mass transfer of physicochemical processes, while increasing the extraction of copper in solution and reducing the duration of the process.

Leaching of ground ore is effectively carried out with a solids content of 10 to 70%. An increase in the ore content during leaching up to 70% allows to increase the productivity of the process, the concentration of sulfuric acid, creates conditions for the friction of particles between themselves and their grinding, and also reduces the volume of apparatus for leaching. Leaching at a high ore content leads to a high concentration of copper in the solution, which reduces the driving force of the dissolution of minerals and the leaching rate, compared to leaching at a low solids content.

Leaching of ore with a particle size of minus 0.1-0.074 mm with a solution of sulfuric acid with a concentration of 10-40 g / dm ³ for 10-60 minutes allows to obtain high copper recovery from oxidized minerals and secondary copper sulfides. The dissolution rate of oxidized copper minerals in a solution of sulfuric acid concentration of 10-40 g / DM ³ high. After leaching of crushed mixed copper ore lasting 5-10 minutes, the content of hard-to-oxidize oxidized minerals in the ore is significantly reduced and is less than 30%, so it goes into the sulfide technological grade. The extraction of copper minerals remaining in the leach cake can be carried out in the flotation mode of sulfide minerals. 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 leach cake and the load on the flotation concentration of the leach cake are significantly reduced and, accordingly, the consumption of flotation reagents - collectors.

Preliminary sulfuric acid treatment of sulfide-oxidized copper ores allows not only to remove hard-to-oxidize oxidized copper minerals, but also to clean the surface of sulfide minerals from iron oxides and hydroxides, to change the composition of the surface layer so that the floatability of copper minerals increases. By the method of X-ray photoelectron spectroscopy, it was found that as a result of the sulfuric acid treatment of copper sulfides, the elemental and phase composition of the surface of minerals changes, affecting their flotation behavior - the sulfur content increases 1.44 times, copper 4 times, and the iron content decreases 1.6 times. The ratio of the phases of sulfur on the surface after sulfuric acid treatment of secondary copper sulfides varies significantly: the fraction of elemental sulfur increases from 10 to 24% of total sulfur, the proportion of sulfate sulfur from 14 to 25% (see drawing: S2p sulfur spectra (type of hybridization of electronic orbitals, characterized by a certain binding energy) of the 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). Given 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, during the leaching of crushed mixed copper ore, the surface composition of copper sulfide minerals changes, affecting their flotation qualities, in particular:

- increases the content on the surface of sulfide minerals of copper of elemental sulfur, which has hydrophobic properties, which reduces the consumption of collectors for flotation of copper sulfide minerals;

- the surface of copper minerals is cleaned of iron oxides and hydroxides that shield the surface of the minerals, so the interaction of minerals with the collector is reduced.

For further processing of leaching products, the leaching cake is dehydrated, which can be combined with leaching of the leaching cake, for example, on belt filters, from the moisture contained in the copper cake. A variety of filtering equipment is used to dewater and rinse the ore leach cake, for example, filter centrifuges and belt vacuum filters, as well as precipitation centrifuges, etc.

The ore leach solution and the ore leach cake washings 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 obtained cathode copper, especially when using the liquid extraction process with an organic extractant. Suspension can be released in the simplest way - clarification, as well as additional filtering.

Copper is extracted from the clarified copper-containing ore leaching solution and leaching of the leaching cake to obtain cathode copper. A modern method for extracting copper from solutions is the method of liquid extraction with an organic cation exchange extractant. Using this method, selectively extract and concentrate copper in solution. After copper reextraction from the organic extractant, electroextraction is performed to obtain cathode copper.

During the 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 the 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 leaching the leaching cake. In this case, the concentration of sulfuric acid in the residual moisture of the leach cake increases.

When copper is electrolyzed from purified impurities, such as iron, and concentrated by liquid extraction of copper-containing solutions, a spent electrolyte is formed with a concentration of 150-180 g / dm ^{3 of} sulfuric acid and 25-40 g / dm ^{3 of} copper. As well as extraction raffinate, the use of spent electrolyte for leaching and washing the leach cake reduces the consumption of fresh acid for leaching, copper loss, and it is rational to 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, the particles are reduced in size and the size of the leaching cake corresponds to a flotation of 60-95% of the class minus 0.074 mm.

In Russia, an alkaline medium is used for flotation enrichment of copper minerals, which is determined by the predominant use of xanthogenates as collectors, which are known to decompose under acidic conditions, and, in some cases, the need for pyrite depression. To regulate the environment during alkaline flotation, lime milk is most often used in industry as the cheapest reagent, which allows raising the pH to strongly alkaline values. Calcium entering the flotation pulp with milk of lime to some extent screens the surface of the minerals, which reduces their floatability, increases the yield of enrichment products and reduces their quality.

During the processing of mixed copper ores of the Udokan deposit, the crushed ore after sulfuric acid treatment is washed from copper ions with an acid extraction raffinate, spent electrolyte and water. As a result, the moisture of the leach cake has an acidic environment. For the subsequent flotation of copper minerals in alkaline conditions, washing with a large flow rate of water and neutralization with a large flow rate of lime are necessary, which increases the cost of processing. Therefore, it is advisable to flotation enrichment of sulfide copper minerals after sulfuric acid leaching to carry out in an acidic environment, at a pH of 2.0-6.0 to obtain copper concentrate and tailings.

Studies have shown that in the main flotation of copper minerals from sulphate leaching cakes, when the pH value decreases, 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 cakes of sulfuric acid leaching of copper ore of the Udokan deposit at various pH values pH Products Exit The copper content,% Copper recovery,% g % 2 Flotation Concentrate 19.44 10.71 10.77 85.07 Control flotation concentrate 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 four 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 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 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 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 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 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 higher the copper content in the concentrate, the yield and recovery. The yield of the control flotation concentrate in an acidic medium is large (18.36%), with an increase in the pH value, the yield of this concentrate decreases to 7%. The extraction of copper in the total concentrate of the main and control flotation in the entire range of the studied pH values is almost the same and is about 95%. Flotation recovery at a lower pH is higher than copper recovery at a higher pH, due to the large yield in concentrates under acidic flotation conditions.

After sulfuric acid ore treatment, the flotation rate of sulfide copper minerals increases, the time of the main and control flotation is only 5 minutes, in contrast to the ore flotation time of -15-20 minutes. The flotation rate of copper sulfides is much greater than the rate of decomposition of xanthate at low pH values. The best flotation enrichment results are achieved using several collectors from a number of potassium butyl xanthate, sodium dithiophosphate, sodium diethyl dithiocarbamate (DEDTA), aeroflot, pine oil.

According to the residual concentration of xanthate after interaction with copper sulfides, it was experimentally determined that 1.8 x 2.6 times less xanthogenate is adsorbed 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 elemental sulfur content on the surface of copper sulfides after sulfuric acid treatment, which, as is known, increases its hydrophobicity. Studies of the foam flotation of secondary copper sulfides showed (abstract of the dissertation “Physicochemical Foundations of Combined Technology for Processing Copper Ores of the Udokan Deposit” Krylova LN ”) that sulfuric acid treatment leads to an increase in copper recovery in concentrate by 7.2–10.1% a solid phase yield of 3.3 ÷ 5.5% and a copper content in concentrate of 0.9 ÷ 3.7%.

The invention is illustrated by examples of the method:

Example 1

Mixed copper ore of the Udokan deposit, containing 2.1% copper, of which 46.2% are in oxidized copper minerals, was crushed, crushed to a particle size of 90% of the class minus 0.1 mm, leached in a vat with stirring at a solids content of 20% , the initial concentration of sulfuric acid 20 g / DM ³ while maintaining the concentration of sulfuric acid at 10 g / DM ³ for 30 minutes. For leaching, extraction raffinate and spent electrolyte were used. The leach cake was dehydrated on a vacuum filter and washed on a belt filter with extraction raffinate and water.

Flotation enrichment of the sulfuric acid leach cake was carried out at pH 5.0 using potassium butyl xanthate and sodium diethyl dithiocarbamate (DEDTA) as collectors in an amount 16% less than for flotation of the crushed copper leaching cake of copper ore with a particle size of 1-4 mm. As a result of flotation enrichment, the recovery of copper in the total sulfide copper concentrate was 95.1%. Lime for flotation concentration was not used, which in alkaline flotation of leaching cake is consumed in an amount of up to 1200 g / t of ore.

The leaching liquid phase and the washings were combined and clarified. The extraction of copper from solutions was carried out with a solution of the organic extractant LIX 984N, and cathode copper was obtained by copper electrolysis from a copper-containing acid solution. Through recovery of copper from ore by the method amounted to 91.4%.

Example 2

The copper ore of the Chineisk deposit, containing 1.4% copper, in which 54.5% are in oxidized copper minerals, was crushed and ground to a particle size of 50% class minus 0.074 mm, leached in a vat with stirring at a solids content of 60%, the initial concentration sulfuric acid 40 g / dm ³ using a spent electrolyte. The leach pulp was dehydrated on a vacuum filter and washed on a belt filter, first with spent electrolyte and extraction raffinate, then with water. The leach cake without regrinding was enriched by flotation at pH 3.0 using xanthate and aeroflot with a flow rate (total flow rate of 200 g / t) lower than with ore flotation (collector flow rate of 350-400 g / t). The recovery of copper in sulfide copper concentrate was 94.6%.

The leaching liquid phase and leaching cake washings were combined and clarified. The extraction of copper from solutions was carried out with a solution of the organic extractant LIX, cathode copper was obtained by electroextraction of copper from a copper-containing acid solution. The through extraction of copper from ore into commercial products amounted to 90.3%.

Claims (8)

1. A method of processing mixed copper ores, including crushing and grinding ore, leaching the crushed ore with a solution of sulfuric acid with a concentration of 10-40 g / dm ³ with stirring, the solids content of 10-70%, duration 10-60 min, dewatering and washing cake ore leaching, combining the liquid ore leaching phase with leaching cake washings, releasing the combined copper-containing solution from solid suspensions, extracting copper from the copper-containing solution to obtain cathode copper and flotation of copper mi neral from the leach cake at a pH of 2.0-6.0 to obtain a flotation concentrate. 2. The method according to claim 1, in which the grinding of ore is carried out to a particle size component of 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 leaching is carried out simultaneously with its dehydration 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 resulting from liquid extraction is used to leach the ore and to wash the leach cake. 8. The method according to claim 6, in which the spent electrolyte formed during electrolysis is used to leach ore and to flush the leach cake.

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