Beneficiation test of a complex refractory lead-zinc polymetallic sulfide ore

Currently, lead-zinc ore component of the world more and more complex, dense symbiosis between the various minerals, complex relationships disseminated, lead-zinc multi-metal mineral beneficiation has become one of the problems of heavy metal. The treatment of such ores is mainly based on flotation at home and abroad. A lead-zinc mine in Hebei is a large-scale silver -bearing polymetallic symbiotic sulfide ore deposit. There are many kinds of ore types, and the main valuable metal elements are galena and sphalerite. Wherein the lead ore, zinc sulphide ore close symbiosis, green and mutually interconnected fine inclusions was slightly, disseminated sulphide ore particle size is uneven, and the presence of secondary copper minerals sulfide mineral separation influenced, is easily Floating difficult to mine. According to the nature of the ore, we have adopted the lead-zinc priority flotation process, coupled with a reasonable pharmaceutical system, successfully achieved lead and zinc separation, and achieved good flotation indicators.

First, the nature of the ore

(1) Multi-element analysis of raw ore

The results of multi-element analysis of raw ore are shown in Table 1-2. As can be seen from Table 1-2, the ore belongs to a complex silver-containing polymetallic symbiotic sulfide ore.

Table 1 Results of multi-element chemical analysis of ore and minerals% (1)

Table 2 Multi-element chemical analysis results of ore and minerals% (2)

(II) Analysis of the original mineral phase

The results of analysis of lead and zinc phases in raw ore are shown in Tables 3 and 4. The phase results show that the lead and zinc in the ore are mainly in the form of sulfides, and the oxidation rates of lead and zinc are relatively low.

Table 3 Results of chemical phase analysis of lead

Table 4 Results of chemical phase analysis of zinc

(3) Main metal mineral inlay characteristics

The galena is the most important carrier of lead in the ore, and the relative content of minerals is 4.44%. The ore content of ore in the ore is mostly distributed in the range of 0.010-0.2 mm and the maximum particle size is 0.8 mm. The symbiotic relationship between galena and sphalerite and chalcopyrite is very close, often forming a complex mineral aggregate and closely co-existing. The coarse and fine galena in the ore are often closely symbiotic with the sphalerite, and the fine-grained sphalerite inclusions are common in the medium-thick galena, while the fine-grained galena is often irregularly composed with sphalerite. The co-edge structures are embedded together in the gangue minerals, and the sulphide aggregates they form are also relatively fine. Galena ore and sphalerite addition, the magnet complex ore mineral aggregates composed of closely associated, but also often has an irregular shape in disseminated gangue minerals.

The sphalerite in the ore is unevenly distributed in different light sheets. It is more common that the sphalerite and galena complexes form a complex sulfide aggregate or a complex co-edge structure with magnetite and a fine-grained structure. Cloth feature. The sulfide aggregates composed of sphalerite and galena in the ore are very complex, or the symbiotic boundary is extremely irregular or embedded in the magnetite in the form of inclusions, and most sphalerites are only in fine grinding conditions. Monomer dissociation can be achieved, which is an important mineralogical factor affecting the separation of lead and zinc.

Second, research methods

(1) Grinding fineness test

Grinding fineness is an important process condition for flotation separation. Reasonable grinding fineness not only ensures sufficient monomer cleavage of each target mineral, but also avoids excessive pulverization. According to the nature of the ore, combined with the grain size characteristics of the ore useful minerals, the grinding fineness -74μm was tested at 65%, 75%, 85%, 90%. The test results are shown in Figure 1.

The test results show that the lead crude recovery rate increases slowly with the increase of grinding fineness, but the amplitude is not very obvious. The grade of lead rough-selected concentrates is increasing with the increase of grinding fineness and the amplitude is relatively obvious. When the grinding fineness -74μm reaches 85%, the lead grade in coarse concentrates tends to moderate. The zinc occupation rate in lead crude concentrate is not obvious in the fineness of grinding -74μm 65%～90%. Considering comprehensively, the grinding fineness -74μm is selected to be 90% for the grinding fineness used in the test.

(II) Lead flotation condition test

According to the results of the grinding fineness test, the ore is ground to -74 μm for 90% for preferential flotation. The test uses a rough selection and a sweeping process.

1. Lead pH test

The pH value of the slurry is relatively high in the floatability of the lead ore and the interaction between the agent and the mineral. Lime was selected as the pH adjuster for lead-slurry slurry. The test results are shown in Figure 2.

The test results show that the change of pH value has obvious influence on the grade and recovery rate of lead in crude lead concentrate. When the CaO is low, the higher the recovery of lead concentrate grade is lower, and the lead is increased with the increase of CaO dosage. The grade gradually declined and the lead recovery rate gradually increased. When the amount of CaO reached 500g/t, the grade change of lead began to slow down and decreased significantly at 1500g/t. The lead recovery rate decreased with the increase of CaO dosage, indicating that the large amount of CaO is unfavorable for the flotation of lead. The grade of zinc in lead concentrates did not change significantly with the change in CaO dosage. Considering the right amount of CaO added.

2. Zinc inhibitor test

The key to lead and zinc beneficiation is lead and zinc separation. The key to lead and zinc separation is to choose an effective zinc inhibitor. The effect of zinc inhibition directly affects the selection of lead and zinc selection indicators. In ore dressing, two or more combination agents are often used to improve the effect of the medicament. The commonly used inhibitor of zinc is zinc sulfate, and zinc sulfate is generally used in combination with other agents. The sphalerite activity in the ore sample used in this test is relatively high and easy to float and difficult to suppress. After several screenings, several experimental protocols were identified: ZnS0 ₄ + Na ₂ S0 ₃ combination, ZnS0 ₄ + FS/NS combination, ZnS0 ₄ + Na ₂ S0 ₃ + FS/NS combination (FS and NS are inorganic salts) , the same as below).

The experimental results show that ZnS0 ₄ +Na ₂ S0 ₃ +FS is the best combination of the ore minerals. The amount of these three inhibitors was adjusted separately, and the synergistic effect of the three agents was finally determined. The amount of the combination agent was determined to be ZnS0 ₄ (4000 g/t) + Na ₂ S0 ₃ (1000 g/t) + FS (300 g / t). At this time, the flotation index of lead crude concentrate is: lead grade is 66.58%, lead recovery rate is 82.25%, zinc grade is 4.86%, and zinc occupation rate is 12.09%. The test flow is shown in Figure 3.

3. Lead- collecting agent test

In the lead-selective collector test, several experimental schemes were designed for comparative study: single ZSN method, single AN method, ZSN+AN method, ZSN+ethyl yellow medicine method (ZSN and AN are both sulfur-nitrogen organic compounds). The test results are shown in Table 5.

Table 5 Test results of lead collector type test

The test results show that the combined flotation effect of ZSN+ethylxanthate is the most ideal in these collector schemes. At this time, the lead grade in lead crude concentrate reaches 29.36%, and the lead recovery rate reaches 94.10%. .

(III) Zinc flotation condition test

1, zinc selection pH test

In order to select the lead tailings for zinc rough selection, the pH value of the pulp required for zinc selection is first determined. The test used CuS0 ₄ 50g/t as the activator, butyl xanthate 20g/t as the collector, and CaO as the pH adjuster as the variable. The test results are shown in Figure 4.

Tests have shown that as the amount of CaO added increases, the flotation index of zinc decreases. For overall consideration, choose to add little or no lime.

2, copper sulfate dosage test

CuS0 _{4 was} selected as the zinc rough activator, and the test results are shown in Fig. 5.

The test results show that the flotation index of zinc increases with the increase of CuSO ₄ dosage, but the flotation index is the best when CuSO ₄ is l00g/t, then the zinc grade does not change when CuSO ₄ dosage continues to increase. And the recovery rate has dropped. Therefore, it is best to add CuSO ₄ 100g/t.

3. Zinc-selective collector test

The butyl xanthate was selected as the collector for zinc selection and the pine oil as the foaming agent. The amount of pine oil is added in proportion to the amount of butyl yellow. The test results are shown in Figure 6.

It can be seen from the test results that the zinc grade and the recovery rate are opposite with the increase of the amount of butyl yellow. Considering that the increase in the amount of butyl yellow can cause some of the better floatable pyrite to float, which is unfavorable for subsequent selection operations, the amount of butyl xanthate is appropriate.

4, selected re-grinding test

In the exploratory experiment, it was found that the zinc concentrate was no longer directly selected for grinding, and it was difficult to increase its flotation index in the closed circuit test. The zinc grade was difficult to reach more than 50%. For this purpose, the zinc coarse concentrate regrind test was carried out, and the test results are shown in Fig. 7.

The test results show that after the re-grinding of zinc concentrate, the grade and recovery rate of zinc in zinc concentrate can be effectively improved, the grade of zinc concentrate product in closed circuit test and the recovery rate of zinc are ensured, and the process is smoother.

Third, flotation closed circuit process test

Based on the above conditional tests, a better pharmaceutical system was selected for the priority flotation closed-circuit process test. The selection of lead in the closed-circuit process is a rough selection, two sweeps, and four selections. The selection of zinc is one rough selection, two sweeps, five selections, and zinc concentrate re-grinding. The results of the closed circuit test are shown in Table 6.

Table 6 Flotation closed circuit test results%

The silver grade unit is g/t.

It can be seen from Table 6 that the closed-circuit test has obtained better sorting index. The main minerals lead and zinc have obtained high-quality concentrate products and considerable recovery rate, of which lead concentrate contains 71.4% lead and the recovery rate is 94.9%. Zinc concentrate contains 55.5% zinc, the recovery rate reaches 70.9%, and the total recovery rate of associated silver also reaches 76.34%, and the lead and zinc mutual inclusion indexes are ideal.

Fourth, the conclusion

1) The ore used in this test is a silver-containing polymetallic symbiotic sulfide ore. There are many minerals in the ore. The symbiotic relationship between the sulfide minerals in the ore is close, and the inlay size is not uniform, which leads to the grinding process, the sorting process and the medicament. The system is more complicated and belongs to the easy-floating and difficult-to-mine mine.

2) The zinc mineral inhibitor was systematically studied during the separation process of lead and zinc, so that the zinc content in the lead concentrate was reduced to about 3%.

3) After continuous adjustment and optimization of the test procedure and the pharmaceutical system, the test achieved good separation results. The sorting index obtained by the closed circuit test is lead concentrate with lead content of 71.4%, recovery rate of 94.9%, zinc concentrate containing 55.5% of zinc, recovery rate of 70.9%, and total recovery of associated silver reaching 76.34%.

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