Production practice of copper recovery from gold concentrate cyanide tailings

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A summary of the measures of technical comprehensive recycling stations gold mine gold cyanidation copper slag Guangdong river taken, as well as economic and technical indicators obtained after the transformation.
Key words gold concentrate, cyanide tailings, flotation, comprehensive recovery, 1. Introduction The ore deposit of Hetai gold deposit in Guangdong is a gold-bearing ore-poor rock-bearing type ore with gold, silver and copper. The original design beneficiation process of the plant is a single flotation gold and copper process. In order to realize the real estate gold, at the end of 1998, a 100t gold concentrate cyanide plant was built to form a flotation-gold concentrate cyanide gold extraction process. Due to the limitation of the production scale of the original flotation process, the gold ore cyanide process can only supply 50t/d, and the valuable copper minerals in the cyanide tailings cannot be comprehensively recovered.
The minerals contained in the flotation gold concentrate are mainly chalcopyrite-based primary minerals and secondary copper sulfide minerals. The two copper minerals have little effect on cyanide leaching. To this end, it was decided to use the gold concentrate cyanide tailings float copper process for the comprehensive recovery of copper and remaining gold and silver minerals.
2. Material composition of cyanide tailings 2.1 Raw ore properties The ore is a sulphide-rich mylonite-type gold-bearing ore with a low content of metal minerals in the ore. Metallic minerals are mainly pyrite, pyrrhotite, chalcopyrite, native gold, a small amount of co sphalerite, galena and arsenopyrite. The metal mineral content accounts for about 2.27% of the ore mineral content. Gangue minerals quartz, sericite, followed calcite, feldspar and the like.
2.2 Cyanide tailings analysis Because the main object of this process research is cyanide tailings, the multi-element analysis and the main phase analysis of the target mineral copper minerals were carried out. The results are shown in Table 1 and Table 2, respectively.

Table 1 Table of results of multi-element analysis of cyanide tailings

element

Cu

Fe

S

Al 2 O 3

SiO 2

C

Pb

Zn

Au ( g/t )

Ag ( g/t )

W B /%

2.5

15.36

13.48

4.42

45.6

0.65

0.31

0.23

2.68

30

Table 2   Cyanide tailings copper mineral phase analysis results

Phase name

Cu/ copper oxide

Cu/ secondary copper sulfide

Cu/ raw copper sulfide

all bronze

W B /%

0.99

0.056

0.176

0.241

W relative B /%

3.73

23.24

73.02

100

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3 Process production practice research Through the analysis of ore properties and small-scale experimental research on cyanide tailings, it is decided to use the flotation process to recover copper minerals and residual gold and silver minerals in the leaching residue, which affects the cyanide residue in the original production process. The main problems of flotation were analyzed and corresponding reform measures were taken.
The grinding fineness required for cyanidation of flotation concentrate in the original production process is -0.037mm, accounting for 90%. Under this particle size condition, we have determined the monomer dissociation of copper minerals. The results are shown in Table 3.

Table 3   Copper mineral monomer dissociation measurement results

Copper mineral presence

Monomeric copper mineral

Copper minerals and gangue

Copper minerals and pyrite

Copper minerals and pyrrhotite

Gangue wrapped copper mineral

total

W relative B /%

48.6

26.4

1.5

7.2

16.3

100

It can be seen from Table 3 that the monomer dissociation degree of the copper mineral in the leaching residue is not high, only 48.6%, which will affect the grade of the flotation copper concentrate. To this end, in order to achieve the goal of maximizing the recovery rate under the premise of satisfying the copper concentrate grade, it is required to strengthen the management of grinding operations in production. The main measures taken are: reducing the concentration of the cyclone feed, stabilizing its ore supply and ore concentration, increasing the working pressure of the cyclone, improving the classification efficiency of the cyclone, and thus grinding under the existing conditions. The fineness reaches -0.037mm, accounting for more than 95%. The flotation operation conditions are strictly controlled to achieve a higher recovery rate while ensuring the copper concentrate grade.
The Hetai Gold Mine has higher requirements for environmental protection. The production tail liquid of the front cyanidation process is zero-emission, and the replacement of the poor liquid is returned to the washing operation. The original designed sodium cyanide recovery system is idle for a long time, so the cyanide content of the thickener under the washing is still high, generally up to 2 ~6×10 -6 . Such a high cyanide concentration will have a strong inhibitory effect on copper minerals. To this end, the following scheme was adopted to eliminate the impact. First, the cyanide tailings were pressure-filtered by a chamber filter press to make the water content of the filter cake not higher than 15%, and then added to the water-skiing slurry to a concentration of 27.5%. The cyanide concentration in the flotation pulp can be greatly reduced, and the influence of cyanide on the copper selection operation can be eliminated. At the same time, the addition of CS agent further eliminates the influence of residual cyanide, and on the other hand activates secondary copper minerals and partially oxidized minerals and continuum minerals to achieve the goal of maximizing the recovery rate of flotation operations.
The flotation concentrate in the original flotation concentrate has a high content, and has not undergone de-treatment before cyanidation leaching. Although after grinding and grading and washing operations, the residual flotation agent in the cyanide residue still seriously affects the copper minerals in the lower stage. Recycling. The production of a large amount of foam, so that the indicators can not be controlled and the flotation operation seriously troughing problems, etc., bring difficulties to the copper selection process. The filtration of the chamber filter press greatly eliminates the effects of residual chemicals. Through the adjustment of the types and dosages of new copper selected drugs, the copper concentrate grade and recovery rate are better controlled.
The box filter press used in the production is intermittent discharge. With the fluctuation of the previous cyanidation operation, the amount of each ore discharge and the interval of the ore discharge can not be fixed, and the flotation production of copper selection generally requires the process parameters to be upgraded. Therefore, the required ore concentration and the ore concentration are relatively Stable, for this purpose, three-stage mixing operation is set up before the floating copper operation. One section is the pulping operation to ensure the slurry concentration is 27%; the second section is the buffering operation to ensure sufficient ore storage during the pre-filtration interval; the third section is the feeding operation to ensure the mine to be fed into the flotation operation. The amount and concentration are uniform and continuous.
4. Process flow, equipment and working conditions after transformation According to the on-site process research, the main equipment selected for cyanide slag copper selection process is pressure filter equipment: XAZ120m 2 box automatic filter press: 1 #搅拌槽: ф2500 x 2500mm mechanical stirring tank; 2 # stirring tank: ф 2500 x 2500mm punching 1500 x 1500mm mechanical stirring tank; 3 # stirring tank: like 500 x 2500mm mechanical stirring tank; rough selection: SF-4m3 flotation machine 2 ); one selection: 2 sets of SF-4m 3 flotation machine (original); secondary selection: 1 set of SF-4m3 flotation machine (original); secondary sweeping: SF-4m3 flotation machine 1 Taiwan (original); [next]
Cyanide slag flotation operation conditions: treatment of ore 50t / d; grinding fineness: -320 mesh accounted for 95%; filter cake water: not more than 17%; slurry flow: 117L / min; pulping concentration: 27%; Optional drugs: xanthine 80 to stay t, No. 2 oil 60g / t; one plus dosing: xanthate 40 g / t, No. 2 oil 30 g / t; two sweep dosing: xanthine 20 g / t, 2 No. 20 g/t; CS dosage: 200 g/t.
5 Production process indicators and technical and economic analysis 5.1 Production process indicators After 4 months of production operation, the main technical indicators obtained are shown in Table 4.

Table 4   Cyanide tailings flotation process index

Original copper accumulated copper grade /%

Tailings cumulative copper grade /%

Total copper grade concentrate /%

Recovery rate /%

4.14

0.55

18.87

/%

5.2 Economic and technical indicators 1) Calculation of output value. The treated ore is calculated according to 50t/d, the annual working days are calculated according to 300d, the copper grade of cyanide slag is 4%, the comprehensive recovery rate is 85%, the copper concentrate grade is 18%, and the copper price is based on the current price of 11 500 yuan / t, the annual output of copper 510t, the content of copper sales revenue of 5.865 million yuan.
In addition, the gold grade in the copper concentrate is 6 years old, and the gold in the concentrate is 40 yuan/g. The total income of the gold sales is 680,000 yuan. The total annual income is 6.545 million yuan.
(2) Total annual cost calculation. The total annual cost includes production costs and sales costs. Among them, the production cost includes electricity consumption, drug consumption, labor and material consumption, and its annual total is 650,200 yuan. The cost of sales includes labor and freight, with a total annual amount of 850,000 yuan, and the total cost of the two totals is 1.502 million yuan.
(3) The tax is calculated based on 12% of the sales revenue, and the total amount is 703,800 yuan (excluding the gold content).
(4) The annual sales of copper concentrates was 4.341 million yuan.
6 Conclusion Through a comprehensive study of the on-site process and ore material composition of the Gaoyao Hetai Gold Mine in Guangdong, the flotation process was used to comprehensively recover the copper and residual gold in the gold concentrate cyanide tailings, and the process on the site was modified to The cyanide slag recovery copper flotation plant has been put into production successfully, achieving the purpose of comprehensive recycling and bringing significant economic benefits to the enterprise. Copper recovery from cyanide slag is technically and economically feasible, so it can provide a good reference for tailings recovery similar to ore.

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