Experimental study on beneficiation process of a lead-zinc mine

China is rich in lead zinc mineral resources. Lead and zinc as an important non-ferrous metal mineral resources play an important role in the national economy, widely used in electrical, mechanical, military, metallurgy, chemical industry, light industry and pharmaceutical industry. Yunnan a lead-zinc-rich metal lead, zinc sulfide ore grade of 4.67% of lead, zinc grade of 18.89%, accompanying elements silver, cadmium, germanium, and pyrite utilization reached a target, ore The economic value is higher.

First, the nature of the ore

The results of multi-element chemical analysis of raw ore are shown in Table 1. The chemical phase analysis results of lead and zinc in ore are shown in Tables 2 and 3.

Table 1 Results of multi-element chemical analysis of ore

Table 2 Results of chemical phase analysis of lead and zinc

From the analysis results of Tables 1-2, it can be seen that the lead and zinc grades in the ore are both high, and the associated elements silver, cadmium and antimony all meet the requirements of comprehensive utilization index, and pyrite can also be comprehensively recovered. The oxidation rate of zinc in the ore is low, only 2.61%, and the oxidation rate of lead is 8.57%. The ore sample is a primary sulfide ore. The rock-forming elements in the ore are mainly calcium and magnesium . It can be inferred that the gangue minerals in the ore are mainly carbonate minerals.

The structure of the ore mainly includes a massive structure, a disseminated structure, a vein-like and a vein-like structure, and a strip-like structure. The structure of the ore mainly includes grain structure, self-crystal structure, semi-automorphic crystal structure, inclusion structure, and interstitial structure.

There are many types of minerals in the ore. Lead minerals mainly independent galena, there are a small amount of white lead, lead-containing minerals as well as other fine sulfur arsenic lead, lead sulfate or sulfur arsenic block lead, arsenic, antimony, sulfur, lead, sulfur, arsenic, lead and copper ore , sulfur arsenic silver lead ore. The independent mineral of zinc is sphalerite. The independent minerals of silver are mainly sulfur, arsenic, copper and silver. The independent minerals of sulfur are mainly pyrite, and there are still traces of pyrite and pyrrhotite. The independent mineral of the harmful element arsenic is arsenopyrite. Other metal minerals include chalcopyrite, beryllium copper, hematite, and limonite. Gangue minerals are dolomite, ankerite, calcite, followed by a small amount of quartz, sericite, muscovite, clay minerals. Gangue minerals as well as other carbonaceous material, apatite, rutile, zircon and the like. The inlay characteristics of the main recycled minerals are as follows:

Galena is the most important lead mineral in ore. It is mainly produced in irregular shape. It is closely related to sphalerite, pyrite and leucox, and is often closely symbiotic. The common galena is irregular. It is embedded in sphalerite, and has a star-shaped, net-like galena. The size of the galena is very fine, which is difficult to separate from the sphalerite monomer, so it is easy to be lost to zinc concentrate. in. As a result of the oxidation, the lead ore is often edging or residual structure along the edge or crack of the galena, and its embedding relationship is very complicated. In the operation of flotation of lead sulfide, they are easily lost in tailings, which is one of the important reasons that affect the recovery rate of lead ore . Galena is often filled along the pyrite fractures or gaps to form a more complex mosaic relationship. In the coarse-grained pyrite, galena inclusions are also visible, and the inclusion size is generally 3 to 1 μm. Galena is the most important carrier mineral in silver in ore, and most of the silver is present in galena.

Sphalerite is an independent mineral of zinc and the most important metal mineral in ore. It is mainly embedded in gangue minerals. It is closely related to pyrite and galena. It is closely symbiotic. The galena is often embedded in the sphalerite gap or fissure. Sometimes the galena is fine veins. Embedded in the sphalerite crack, the pulse width is very thin, generally 2 ~ 5μm, it can also be seen that the galena is star-shaped, worm-like embedded in sphalerite, this part of the fine-grained galena is difficult to single The dissociation is easy to lose in the zinc concentrate; when the sphalerite is cemented to replace the pyrite crumb, the embedding relationship is very complicated. A part of fine-grained pyrite is also difficult to separate from the sphalerite monomer. It is easy to enter the zinc concentrate in the operation of flotation sphalerite, and sometimes the sphalerite inclusions are also found in the coarse-grained pyrite. The particle size is generally from 5 to 11 μm.

Second, the test results and discussion

The traditional flotation process for lead-zinc sulfide ore includes two major categories: preferential flotation and mixed flotation. At present, based on this, it has evolved into a principle process of many different structures, such as lead-zinc-pyrite direct priority flotation process, preferential lead-zinc-sulfur mixed-zinc-sulfur separation scheme, lead-sulfur mixed-selection- The process of obtaining lead-zinc mixed concentrate by zinc flotation-lead-sulfur separation scheme. In recent years, due to the poor, fine and miscellaneous nature of the ore processed by some lead-zinc concentrators, the ore dressing researchers and the engineers of the concentrator have succeeded in researching some new processes, such as asynchronous mixed flotation processes and branch floats. Select a process, a floatable process, a floatable asynchronous flotation process. The preliminary flotation and mixed flotation exploration test results of the test ore indicate that it is easier to obtain high-quality concentrates by preferential flotation, so priority flotation is used for detailed conditional tests.

(1) Grinding fineness test

According to the results of process mineralogy, the grain size of lead minerals is finer than that of zinc minerals. Therefore, the grinding fineness test mainly investigates the effect of grinding fineness on the floatability of lead minerals. The test conditions were as follows: the amount of zinc sulfate was 2000 g/t, the amount of sodium sulfite was 200 g/t, the amount of collector SN-9 was 60 g/t, the amount of foaming agent BK204 was 25 g/t, and the flotation time was 6 min. The test results are shown in Figure 1. Considering the grade and recovery rate of lead crude concentrate, the grinding particle size is preferably 70%-74μm.

Figure 1 Effect of grinding fineness on the selection index

1- lead grade; 2-zinc grade; 3- lead recovery; 4-zinc recovery;

(2) Lead coarse selection lime test

To enhance the inhibition of lime, lime is added to the ball mill . The lime dosage test process conditions are that the amount of zinc sulfate is 2000 g/t, the amount of sodium sulfite is 200 g/t, the amount of collector SN-9 is 60 g/t, the amount of foaming agent BK204 is 25 g/t, and the flotation time is 6 min. The test results are shown in Figure 2. As can be seen from Fig. 2, the amount of lime is preferably 3000 g/t. At the same time, it can be seen that the lead content in the tailings is relatively high. For this reason, a rough lead selection is added in the following test.

Figure 2 Effect of the amount of leaded lime on the selection index

(III) Trial extraction of lead sulfate

The test conditions of zinc sulfate dosage test are lime dosage 3000g/t, sodium sulfite dosage 200+100g/t (rough selection I+ coarse selection II dosage, the same below), collector SN-9 dosage 60+20g/t, foaming agent BK204 dosage It is 25 g/t and the flotation time is 6+6 min. The test results are shown in Figure 3. As can be seen from Fig. 3, the amount of zinc sulfate is preferably 3000 g/t.

(IV) Lead crude sodium sulfite dosage test

The experimental conditions for the amount of sodium sulfite used were 3000 g/t of lime, 2500+500 g/t of zinc sulfate, 60+20 g/t of collector SN-9, 25 g/t of foaming agent BK204, and flotation time of 6+6 min. The test results are shown in Figure 4. It can be seen from Fig. 4 that the amount of zinc sulfate should not exceed 700 g/t.

Fig. 3 Effect of the amount of lead-selected zinc sulphate on the selection index

Figure 4 Effect of the amount of lead sodium sulfite on the selection index

(5) RAW-9 dosage test for lead rough selection

The SN-9 dosage test process conditions were lime dosage of 3000 g/t, zinc sulfate dosage of 2500+500 g/t, sodium sulfite dosage of 500+200 g/t, foaming agent BK204 dosage of 25 g/t, and flotation time of 6+6 min. The test results are shown in Figure 5. As can be seen from Fig. 5, the amount of SN-P is preferably 50 g/t.

Figure 5 Effect of lead selection of SN-9 on the selection index

(6) Lead selection test

Lime, zinc sulfate, sodium sulfite and regrind test were carried out in the lead selection condition test. The main test results are shown in Fig. 6. The test conditions were lime dosage l00g/t, zinc sulfate dosage 500g/t, sodium sulfite 300g/t, and selection time 5min. It can be seen from Fig. 6 that the zinc content in the lead concentrate is the lowest when the regrind is 98%-43 μm. Considering that the lead cloth has a fine particle size, the regrind particle size is 98%-43 μm.

Figure 6 Effect of regrind on lead selection index

(VII) Zinc flotation lime dosage test

The zinc flotation lime dosage test uses two rough selection processes. The process conditions are 800+200g/t of copper sulfate, 100+50g/t of butyl yellow, 30g/t of pine oil, and 6+6min of flotation time. The test results are shown in Figure 7. As can be seen from Figure 7. The amount of lime is preferably 500 g/t.

Fig. 7 Effect of the amount of zinc coarsely selected lime on the index of zinc flotation

(VIII) Trial of zinc flotation copper sulfate

The process conditions of zinc flotation copper sulfate dosage test are 500g/t lime, 100+50g/t butyl yellow, 30g/t pine oil, and 6+6min flotation time. The test results are shown in Fig. 8. As can be seen from Fig. 8, the amount of copper sulfate is preferably 400 to 600 g/t.

(9) Comprehensive recovery of pyrite

Zinc flotation tailings use sulfuric acid to adjust the pH value to neutral, butyl xanthate as a collector, and pine oil as a foaming agent. The comprehensive recovery exploration test of pyrite is carried out, and the obtained sulfur concentrate grade is 48.56%. The operation recovery rate is 96.50%. It can be seen that the pyrite in the ore can be recovered comprehensively.

(10) Closed circuit test

On the basis of the above condition test and the full open circuit test, a closed circuit test was carried out, and qualified lead concentrate and zinc concentrate were obtained. The test results are shown in Table 3.

Table 3 Closed circuit test results

Fig. 8 Effect of zinc-selective copper sulfate on zinc flotation index

Third, the conclusion

(1) The test ore is lead-zinc sulfide ore, and the grade of ore is 4.67% of lead and 18.89% of zinc. The main recovered metals in the ore are lead and zinc, and pyrite has a comprehensive recovery value.

(2) The lead-zinc preferential flotation process is adopted, and qualified lead concentrate and zinc concentrate are obtained. This process is suitable for treating the lead-zinc ore.

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