Experimental study on flotation of a refractory copper sulfide ore in Anhui

In recent years, China's copper consumption has increased rapidly, but due to the shortage of copper resources, China's copper-smelting raw materials can only meet about one-third of domestic demand. Therefore, strengthening the development and utilization of refractory copper ore is of great significance for expanding China's copper resources and ensuring the supply of domestic copper-smelting raw materials, and at the same time increasing economic benefits for enterprises.

A copper mine in Anhui is an altered contact metamorphic bovine copper sulfide deposit. The ore is difficult to be selected due to the complex mineral composition and embedding relationship and contains a large number of easily floating gangues. The common flotation agent is mixed with copper and sulfur according to conventional copper and sulfur. Separation process for mineral processing trial production, only copper grade 16.85%, recovery rate 81.23% copper concentrate, and design copper concentrate copper grade 21.30%, the recovery rate of 85.50% is very large, resulting in the plant can not be put into normal production. To this end, a new flotation test study was conducted on the ore.

First, the nature of the ore

Some Copper Ore Anhui complex composition, mainly metallic minerals chalcopyrite, pyrite, pyrrhotite and magnetite, part of the copper present in the form of copper oxide and copper binding, in particular of serpentine ore, magnetic pyrite strongly bound copper-containing lots more thereof; major gangue minerals garnet, quartz, talc, serpentine, silica magnesia, hedenbergite, biotite, calcite, muscovite. The main chemical composition analysis results of the ore are shown in Table 1, and the copper phase analysis results are shown in Table 2.

Table 1 Analysis results of main chemical components of ore

Table 2 Analysis results of copper ore phase of ore

The ore structure is mainly crystalline structure, followed by the metasomatic structure of the solid solution separation structure, and the recrystallized structure, the force structure and the internal structure of the grain are locally observed.

Observed under the microscope: the most important copper mineral in the ore is closely related to the gangue, and the coarse, medium, fine and fine particles mainly composed of medium and fine grain inlays are unevenly embedded, often with it. The granules are infiltrated in the gangue or embedded in the gaps or fissures of pyrite, pyrrhotite, magnetite and gangue particles, and are often cut by flaky gangue.

The ore composition is complex, containing refractory copper oxide, combined copper and easy-floating gangue mineral talc, serpentine, etc. Copper minerals are closely related to gangue mineral inlays. These factors have led to the difficulty of selecting a copper ore in Anhui. Sex.

Second, flotation test

(1) Exploratory experiment

According to the site conditions, under the principle of -0.074 mm and 75% grinding fineness, the process of separation of copper-sulfur mixed copper and sulfur was firstly carried out. Mixed flotation, ethyl xanthate and Z-200 are mixed in a ratio of 1:2 as a composite collector of sulfide ore (referred to as MC) J, the foaming agent is pine oil; the flotation is separated by lime. An inhibitor of pyrite, using Z-200 as a collector for chalcopyrite. Exploring the experimental phenomena and results show that talc and other gangue minerals are easy to float, which not only reduces the copper concentrate grade, but also consumes a large amount of chemicals, which has a great influence on the copper recovery rate. Even if the amount of flotation agent is increased, the copper concentrate grade And the recovery rate still falls short of the design indicators (see Table 3). Therefore, in order to obtain a better sorting result, the easy-floating gangue mineral must be separated from the ore before the mixed flotation.

Table 3 Comparison of experimental and design indicators

(2) Determination of grinding fineness

In order to verify that the -0.074mm accounted for 75% of the grinding fineness, the raw ore was ground to different fineness for 2 times of coarse mixing. The agent used was composite collector MC120+60g/t and pine oil 40+20g/t. The test results are shown in Figure 1.

According to the results of Fig. 1, considering the grade and recovery of copper, it is suitable that the fineness of grinding is -0.074 mm and 75%.

(3) Removal of easy-floating gangue minerals

According to the exploratory test, a separation of easy-floating gangue minerals should be added before the copper-sulfur mixed flotation to eliminate their influence on the classification of sulfide minerals. To this end, a new ester drug QL was developed. The medicament has a certain foaming property and has a good collecting effect on talc and serpentine, and can achieve better separation of these easy-floating gangue minerals and sulfide minerals.

Q-L was used to sort the easy-floating gangue minerals from the ore in different amounts. The results are shown in Figure 2.

It can be seen from Fig. 2 that with the increase of the amount of QL, the copper grade in the easy-floating gangue foam product gradually decreases and the copper recovery rate gradually increases. According to the test results, it was determined that the amount of QL was 80 g/t, and the copper recovery rate of the easy-floating gangue foam product was 13.20%.

In order to ensure a high recovery index of the final copper concentrate, the high-selectivity collector Z-200 of copper is used to recover the fine-grained easy-to-float copper minerals entering the easy-floating gangue foam product. The test procedure is shown in Figure 3. The copper grade and recovery index of fine copper concentrate in different Z-200 dosages are shown in Figure 4.

It can be seen from Fig. 4 that when the amount of Z-200 is more than 15g/t, the copper recovery rate of the fine-grained copper coarse concentrate is not increased much and the copper grade is drastically decreased, so the amount of Z-200 is 15g/t.

The mineral composition of the fine-grained copper coarse concentrate and copper-sulfur mixed flotation obtained from the above selected chemical conditions was analyzed. It was found that the content of the easy-floating gangue in both products was <4%, indicating that the test reached the removal of the ore. The intended purpose of the medium-floating gangue mineral.

(4) Mixed rough selection test

The ore after the removal of the easy-floating gangue mineral is subjected to a copper-sulfur mixed crude selection condition test. The MC composite agent is still selected as the collector of the sulfide ore, so that the strong absorption of the ethyl xanthate is organically combined with the high selectivity of the Z-200. The test procedure is shown in Fig. 5. The copper grade and recovery index of the mixed coarse concentrate obtained under different amounts of MC and foaming agent are shown in Fig. 6 and Fig. 7.

According to the test results of Fig. 6 and Fig. 7, it is determined that the total amount of copper and sulfur mixed coarse MC is 150g/t (rough selection I 100g/t, rough selection II50g/t), and the total amount of pine oil is 60g/t (rough selection I40g) /t, rough selection II20g/t).

(5) Copper and sulfur separation lime dosage test

According to the flow of Figure 8, the copper-sulfur separation test was carried out on the mixed coarse concentrate with Z-200 as the collector of copper and the inhibitor of lime as sulfur. The influence of the amount of lime on the copper concentrate index was mainly investigated. The test results are shown in Figure 9.

It can be seen from Fig. 9 that the total amount of lime is 2500g/t (2000g/t for rough selection and 500g/t for selection). At this time, the copper grade of copper concentrate is 24.01%, and the copper recovery rate is 76.54%.

(6) Closed circuit test

On the basis of the mixed rough selection and copper-sulfur separation conditions test, a closed-circuit process test was carried out. In the test, in order to increase the copper recovery rate as much as possible, the sweeping operation was increased once in the process of copper-sulfur mixing and copper-sulfur separation. The test procedure is shown in Figure 10, and the test results are shown in Table 4.

Table 4, closed circuit test results %

It can be seen from the closed-circuit test results that with the new process flow and pharmaceutical system, the copper grade of copper concentrate is 22.78% and the copper recovery rate is 86.80%, both exceeding the design index.

The copper concentrate obtained from the closed circuit test was identified by minerals. The results show that the copper minerals in the copper concentrate are mainly chalcopyrite, followed by the porphyrite, a small amount of blue copper ore, malachite, and various gangue minerals. Content <3%. The particle size analysis and microscopic observation of the tailings show that the copper minerals in the tailings are mainly in the form of fine particles and inclusions which are difficult to recover by flotation. The distribution rate of copper in the -5μm size is 30.56%, which is the result. The main reason for the loss of copper in tailings.

Third, the conclusion

(1) Using a new easy-floating gangue separation-copper-sulfur mixed-copper-sulfur separation process and chemical system to treat a refractory copper sulfide ore in Anhui, obtaining a copper concentrate of copper content of 22.78% and a copper recovery rate of 86.80%. The better selection indicators are 1.48 and 1.30 percentage points higher than the design indicators.

(2) Using the self-developed new agent QL to pre-float the easy-floating gangue minerals in the ore and eliminate its influence on the flotation of sulfide minerals, which is a key measure for the success of the new process.

(3) The combination of ethyl xanthate and Z-200 as a composite collector for sulfide ore flotation not only ensures good selectivity in the flotation process, but also facilitates high recovery.

(4) The new process is applicable to the nature of ore. The chemical system is simple, the dosage is small, and it is easy to industrialize.

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