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Copper ore resources are an important basis for industrial development, but with the gradual depletion of high-grade ore, the efficient use of low-grade copper ore has become a key topic in the field of ore dressing. A low-grade copper ore contains 0.58% copper, accompanied by a small amount of gold, sulfur and other elements, the copper minerals in the ore are dominated by blue chalcopyrite, sulfur-arsenocopper ore, closely symbiotic with pyrite, embedded in the coarse grain size, but some of the copper and sulfur minerals have a complex relationship. For this kind of ore characteristics, this study through process optimisation, developed a set of efficient and economic beneficiation process, and finally obtained a copper concentrate grade 31.17%, recovery rate of 93.53%, sulfur concentrate grade 43.2%, recovery rate of 44.31% of the excellent indicators.
The primary ore is secondary enriched copper sulphide ore, the main metal minerals are pyrite (4.9%) and blue chalcopyrite (0.8%), and quartz (53.8%) and alunite (35.2%) are the main vein stones. More than 70% of copper minerals are blue chalcopyrite, with good floatability, but some copper minerals and pyrite are wrapped or hyphenated, which are difficult to be dissociated by rough grinding. In addition, the ore contains arsenic (1.64%), and the influence of arsenic on the quality of copper concentrate needs to be suppressed through process optimisation.
Based on the characteristics of the ore, the study adopts the three-stage process of ‘one-stage rough grinding and tailing - flash flotation of copper - copper and sulfur mixed flotation and then grinding and sorting’, the specific steps are as follows:
1. Rough grinding and tailing
Purpose: to throw away the low-grade tailings and reduce the subsequent processing capacity.
Process parameters: the original ore is ground to a fineness of -74μm content of 51%, at this time, the tailings copper grade is only 0.024%, copper loss rate of 2.66%.
Advantage: Highly efficient tailing through coarse grinding, reducing energy consumption and chemical costs.
2. flash flotation of copper minerals
Purpose: to quickly recover the high grade copper minerals which are easy to float, and reduce the loss of middle ore cycle.
Key operation:
Chemicals: selective recovery agent SP (10 g/t), appropriate amount of frothing agent.
Flotation time: shorten to 1/3 of conventional flotation, preferentially flotation of blue pyroxene copper ore and sulphur-arsenic copper ore.
Effect: flash flotation copper concentrate grade 31.17%, recovery 93.53%, significantly better than the conventional flotation of 23.87% grade.
3. copper and sulfur mixed flotation and regrinding sorting
Copper and sulphur mixed flotation:
Conditions: weakly alkaline slurry (pH 8-9), using T-based yellow drug and T-based ammonium black drug (ratio 1:2) as a mixed recovery agent, total dosage of 45 g/t.
Function: co-flotation of the remaining copper minerals with pyrite to form a mixed concentrate.
Regrinding and sorting:
Regrinding fineness: grind the mixed concentrate to -74μm content of 95%, to promote the dissociation of copper and sulfur.
Inhibitor: add lime (1000 g/t) to inhibit pyrite and enhance the efficiency of copper-sulfur separation.
Results: After regrinding, the copper and sulfur separation effect is remarkable, the grade of copper concentrate is increased to 8.54%, and the sulfur recovery rate of sulfur concentrate reaches 88.91%.
1. pH value control
Lime dosage: 1000-1500 g/t, not only can inhibit pyrite, but also maintain the pulp pH 10-11, optimising the environment for copper mineral flotation.
Mechanism of action: lime is added in the grinding stage to inhibit the surface activity of pyrite in advance and reduce its interference with copper flotation.
2. Selection and combination of collector
Flash flotation stage: SP collector has high selectivity for blue chalcopyrite, when the dosage is 10 g/t, the copper recovery rate is 84.5%, and the concentrate grade is 22.24%.
Copper and sulfur mixed flotation stage: T-based yellow drug and T-based ammonium black drug combination (ratio 1:2), to strengthen the recovery of hard-to-float copper minerals, while taking into account the recovery of sulfur.
3. The efficiency of regrinding process
Improvement of dissociation degree: regrinding makes the copper-sulfur congeners fully dissociated, and the dissociation degree of copper mineral monomer is increased from 85% to more than 95%.
Surface renewal: the grinding process removes the residual agents on the mineral surface and enhances the inhibition effect of lime on pyrite.
Through the closed-circuit test verification, the final indicators of the whole process are as follows:
Copper concentrate: yield 1.82%, copper grade 31.17%, recovery rate 93.53%, associated gold recovery rate 52.17%.
Sulphur concentrate: yield 6.53%, sulphur grade 43.2%, recovery rate 44.31%.
Tailings: copper loss rate only 3.02%, sulphur loss rate 47.8%.
Economic analysis:
Pharmacy cost: low dosage of SP and combined collector, 20% savings in pharmacy cost per tonne of ore.
Optimisation of energy consumption: rough grinding tail loss reduces the amount of subsequent processing, and energy consumption per tonne of ore is reduced by 15%.
This study successfully realises the efficient separation of low-grade copper ore through the process of ‘rough grinding tailing-flash flotation-copper-sulfur regrinding and separation’. The core of the process is:
Segmented processing: priority recovery of easy-to-float minerals, reducing the circulating load of the middle ore;
Pharmaceutical synergism: the combination of selective collectors and inhibitors improves the separation precision;
Regrinding efficiency: cracking complex congeners through fine grinding to ensure the quality of the final concentrate.
This process provides technical reference for the development of low-grade copper resources, and has significant industrial application value.
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