Lead Zinc is an important non-ferrous metals, lead and zinc as international demand increased year by year and the rapid development of China's industry, the demand for lead and zinc is growing.
A flotation test study on a carbon-bearing fine-grained lead-zinc mine in China was carried out. Two treatments were proposed. One is the floatability of carbon, the other is the floatability of useful minerals and the correlation between carbon and useful minerals. Sex [1] . Generally, there are two kinds of carbon removal processes: one is the lead carbon mixed process; the other is the defoaming process such as decarburization and carbon suppression [2] . On the basis of research on the ore properties of the samples, the ore processing process test was carried out. The mine belongs to the carbon-containing high-zinc low-lead sulfide ore. The test adopts a flotation method of carbon-zinc mixed float-lead-zinc separation.
First, the nature of the ore
(1) Analysis of main components
The chemical analysis results of the main components in the ore are shown in Table 1. The valuable metal elements in the ore sample are zinc and lead. The content of carbon in the ore sample is very high, and the ore sample belongs to the carbon-bearing lead-zinc ore.
(2) Phase analysis and mineral composition
The ore samples were analyzed for the phase of lead and zinc. The degree of oxidation of ore is very low, and lead-zinc minerals mainly exist in the form of sulfides. The main metal minerals are sphalerite and galena. The symbiotic relationship between the two is the key to restricting their rational sorting. Lead and zinc phase analysis and mineral composition are shown in Tables 2, 3 and 4.
(3) Embedding characteristics of important metal minerals in ore
The main metal minerals in the ore sample are sphalerite and galena, and other metal minerals are low. Among them, the sphalerite in the ore has a relatively coarse grain size, and its composition is substantially free of iron . Coarse sphalerite is encased in fine-grained gangue minerals, galena, organic carbon, and other minerals. The galena is filled along the sphalerite fracture or embedded in the sphalerite in the form of inclusions. The size of the inlaid cloth is fine and it is difficult to dissociate the monomer.
The organic carbon in the ore is embedded in the fissures of the coarse sphalerite, or the fine particles are embedded along the periphery of the sphalerite. In addition, a small amount of organic carbon is embedded in the sphalerite in the form of fine-fine particles. Partial organic carbon and sphalerite are difficult to dissociate from the monomer during grinding operations. And the symbiotic relationship between galena and sphalerite is very close. Irregular galena is often embedded in coarse-grain sphalerite, some fine-grained galena is embedded in fine grains, some coarse grains are often wrapped with fine-grained sphalerite; or fine-grained fine-grain galena is wrapped The form of the body is embedded in the sphalerite. Therefore, some organic carbon and galena are difficult to dissociate from the sphalerite sufficient monomer, which makes separation difficult.
Second, the flotation process
(1) Selection of flotation schemes
The conditional test adopts the single factor test method [3] . The general flotation method has the methods of preferential flotation, partial flotation, flotation, and branch flow flotation. In view of the ore properties of the ore sample, the test adopts a flotation method of first floating carbon zinc and then floating lead and zinc respectively. Due to the special relationship between carbon and zinc minerals in the ore, the carbon concentrate contains a large amount of zinc, and the carbon-zinc mixed concentrate is used as a zinc concentrate product. The carbon zinc-lead-zinc flotation principle process is shown in Fig. 1.
(2) Flotation condition test
1. Carbon-zinc mixing test
Due to the high carbon content in the ore, a carbon preferential flotation process is considered. Due to the complex inlaid relationship of carbon and zinc, the zinc which is co-produced with carbon at the same time will also float out. Therefore, the process of carbon-zinc mixing is adopted first. The amount of CaO were carried out, the amount of coal oil, dispersant type and amount test.
Taking CaO as the pulp pH adjuster, the lead and zinc grades and the recovery rate increase with the increase of the amount of CaO. For the carbon-zinc mixing, the natural pH value is better, the CaO dosage is 0, and the pH value is 8.63. The test results are shown in Figure 2.
Since the density of carbon is small, it can be floated by adding a small amount of kerosene. In order to determine whether the amount of kerosene can reduce the loss of lead minerals in carbon-zinc concentrate, the kerosene dosage test is carried out. The kerosene dosage is preferably 60g/t. The test results are shown in Figure 3.
Test water glass and sodium hexametaphosphate as a dispersing agent inhibits phosphate gangue, relatively water glass is better than sodium hexametaphosphate. Appropriate addition of a dispersing agent is beneficial to increase the content of lead in the carbon concentrate, and a small amount of water glass is added to the rough carbon, preferably 500 g/t. The test results are shown in Figure 4.
2. Grinding fineness test
The test grinding fineness was tested at 55%, 65%, 75%, 85%, and 90% with a fineness of -74 μm. As the fineness of grinding increases, the monomer dissociation degree of lead minerals and zinc minerals increases, the recovery rate of lead in lead concentrates increases, zinc minerals become more difficult to suppress, and their occupancy rate in lead concentrates also increases. It is recommended that the rough grinding fineness be 85% in -74μm.
3, carbon zinc selection test
The purpose of carbon zinc-lead separation flotation is to reduce the lead content in the carbon-zinc concentrate. The optimum pH for lead minerals and sphalerite is different for flotation. At higher pH values, flotation of sphalerite is favored, and in the same case, lead ore is effectively inhibited, and it is determined by experiments that the suitable amount is 600 g/t. Na 2 SO 4 was used as an inhibitor of lead minerals. With the increase of the amount of Na 2 SO 4 , the recovery rate of lead reached the lowest at 1500g/t and the inflection point appeared. Therefore, it is more reasonable to select this point. The use of SWS (the code of the dispersant) lead makes the lead in the carbon-zinc concentrate as little as possible to ensure the quality of the carbon-zinc concentrate. According to the test, the final dosage is 200g/t.
4. Lead-zinc separation ZnSO 4
As an inhibitor of sphalerite in the preferential flotation of lead-zinc separation, Na 2 SO 4 acts as an auxiliary inhibitor of ZnSO4 in the suppression of sphalerite. Ethyl sulfide is used as a collector for lead minerals. The test results are shown in Figures 5 and 6.
It can be seen from the test results that ZnSO 4 has a slight inhibitory effect on lead minerals while suppressing sphalerite. The amount should be reasonably selected, and the appropriate addition of Na 2 SO 4 is beneficial to improve the grade of lead in the concentrate, but Na 2 SO 4 , excessive, affects the grade of lead and the recovery rate. The amount of ZnSO 4 used is 2,000 to 3,000 g/t, and the ratio of ZnSO 4 to Na 2 SO 4 is preferably about 4:1. It is more suitable to choose 40 to 50 ethane sulfur.
5. Lead-zinc separation and re-grinding test
The lead-zinc separation regrind test results are shown in Figure 7.
The purpose of regrind is to dissociate lead and zinc further monomer to achieve better separation. As the grinding time increases, the occupation rate and grade of zinc in the lead concentrate decrease, and it is more suitable to select the regrind fineness to be -38.5 μm to account for 85%.
6, zinc flotation
CaO is used as a pulp pH adjuster for sphalerite flotation. The test results are shown in Figures 8, 9, and 10. It is known from the test that the addition amount of CaO is preferably about 2000 g/t. CuSO 4 is an activator that activates the zinc that was inhibited in the previous step. The amount added was determined to be 450 g/t. The amount of the collector xanthate added was 80.
(3) Flotation closed circuit test
In the flotation closed circuit, the sample is ground to -74μm, which accounts for 85%. In the carbon-zinc mixing operation, one rough selection, five selections, and one sweep are used to obtain zinc concentrate. The lead-lead operation is a rough selection, five selections, and two sweeps to obtain lead concentrate. The tailings obtained after lead flotation are subjected to one rough selection, four selections, and two sweeps to obtain zinc concentrate 2, and zinc concentrates 1 and 2 are mixed to obtain total zinc concentrate. The test results are shown in Table 5.
Third, the conclusion
(1) The valuable metal minerals in the ore are sphalerite and galena. The ore contains a lot of organic carbon. Among them, carbon zinc has a complicated symbiotic relationship, and the lead-zinc inlay has a fine particle size.
(2) The carbon-zinc mixed float-lead and zinc separation flotation process was adopted in the test, which solved the problem of carbon-zinc symbiosis and fine-grain grade lead-zinc, and achieved the purpose of recovering lead-zinc minerals in ore.
(3) In order to meet the sales requirements and achieve economic value, zinc concentrate 1 and zinc concentrate 2 are mixed. As a total concentrate, the grades of lead and zinc concentrates meet the standards of qualified concentrates.
references
[1] Feng Junsheng. Carbon removal process of carbon-containing lead-zinc polymetallic ore [J]. Foreign metal ore dressing, 2001, (6): 6-8.
[2] Feng Junsheng. Study on carbon removal process of carbon-bearing lead-zinc polymetallic ore in Inner Mongolia [J]. Baotou Iron and Steel College Journal. 2000, 19 (4): 279-282.
[3] Wang Zi. Floating mineral processing technology [M]. Beijing: Metallurgical Industry Press. 2006.
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