Lead Zinc is an important non-ferrous metals, plays an irreplaceable role in the national economy and industrial development. 80% of the world's lead and zinc are obtained by smelting lead-zinc ore. However, with the continuous mining, the easy-to-select sulfide ore resources are increasingly depleted, and lead-zinc ore resources are being continuously developed. However, due to the complex composition of lead-zinc ore minerals, there are many associated minerals, fine grain size, serious muddy phenomenon, high soluble salt content, and various inevitable ions have great influence on the floatability of lead and zinc. Therefore, at present, only a small number of high-grade lead-zinc ore mines have mining value, and it is difficult to recycle the lead-zinc ore with low grade and difficulty in conventional beneficiation processes. At present, the lead-zinc ore with industrial value mainly includes white lead ore (PbCO3), lead bismuth (PbSO4), zirconia (ZnCO3), and heteropolar ore. China is a major lead oxide and zinc resource resource in China. The zinc concentrate production can not meet the demand, and still rely heavily on imports. Strengthening the research on the recovery and utilization of lead-zinc mine has great practical significance for alleviating the contradiction between supply and demand. Based on a large number of literatures, this paper reviews the methods of processing lead-zinc ore from flotation process, leaching process and combined metallurgy process.
1 flotation process
At present, the lead-zinc ore dressing plant usually adopts a flotation process. A single lead-zinc deposit is rare, and the lead-zinc ore is mainly derived from the oxidation zone of sulfide ore, which contains both oxidized ore and sulfide ore. There are two main principles for the flotation of lead-zinc ore. One is â€œfirst sulfur and then oxygenâ€, which is based on the sequential flotation of galena-sphalerite-lead oxide-zinc oxide ore; Zinc" is a sequential flotation of galena-lead oxide-sphalerite-zinc oxide ore. At present, the flotation process of lead-zinc ore is mainly a flotation flotation method, a fatty acid collector flotation method, a chelating agent flotation method, and a flocculation flotation method.
1.1 vulcanization - xanthate flotation
The vulcanization-xanthate method is an effective way to recover lead and zinc oxide. A large number of studies have been carried out by domestic and foreign mineral processing workers. The mechanism of the vulcanization-xanthate method is to pre-vulcanize the lead-zinc oxide, so that the surface of the lead-zinc oxide is covered with a highly hydrophobic sulfide film, and then the xanthate-type collector is used for flotation. Early studies have found that when the temperature of the slurry is heated to 50~60 Â°C, it will be beneficial to the vulcanization of zinc oxide minerals and the adsorption of chemicals. However, excessive vulcanization agent will inhibit the action of xanthate and mineral surface, and the zinc oxide mineral needs to be added after vulcanization. copper sulfate can be activated after the xanthate collector. The Gorno plant in northern Italy uses the temperature-vulcanization-flotation method to float lead tailings, adjust the pH value of the slurry to 11, and heat the slurry to cure at 45~50 Â°C. After the activation of copper sulfate, the amylose is harvested. The zinc concentrate grade was 38.0% and the zinc recovery rate was 76.4%. Sun Wei et al. used the vulcanization-xanthate method to float the white lead ore and vulcanize-thiophenol to float the heteropolar ore, and studied the flotation process of a lead-zinc ore in Yunnan Wuyuan. Na2S is used as the vulcanizing agent, Dinghuang is the lead collector, thiophenol is the zinc collector, and No. 2 oil is the foaming agent. The lead grade is 53.93%, and the lead concentrate containing zinc is 13.13%. The zinc grade is used. It is 31.82%, zinc concentrate with lead content of 2.75%, and lead-zinc mixed concentrate with lead grade of 33.38% and zinc grade of 19.10%. The comprehensive recovery rate of lead and zinc is over 98%.
The vulcanization-xanthate method is widely used, and is more used for the recovery of lead oxide, but the selectivity is generally poor. It is difficult to obtain better beneficiation indexes for complex low-grade lead-zinc ore. In addition, the heating process and the activation process are required, and the process is complicated and the cost is high.
1.2 Sulfide-amine salt flotation method
The sulfur-amine salt flotation method, also known as the Rey method, was first discovered by Maurice Rey and its assistants, and proved that the primary amine collector is the most effective. At present, the vulcanization-amine salt flotation method has become the main method for flotation of lead and zinc oxide. Most of the domestic lead-zinc oxide plants use the vulcanization-ammonium salt flotation method. The process does not require warming vulcanization, and excess sodium sulfide does not significantly inhibit subsequent flotation. Chen Jinquan et al. conducted a vulcanization-amine salt flotation test on a high- speed iron mud oxide lead-zinc mine with sodium sulfide as a vulcanizing agent and mixed amine (dodecylamine, hexadecylamine, octadecylamine) as a collector. Under the conditions of lead and zinc feeding grade of 3.54% and 5.86%, the lead concentrate grade was 45.23%, the recovery rate was 73.51%, the zinc concentrate grade was 40.56%, and the recovery rate was 76.21%. Li Yuqiong et al. used a vulcanization-amine salt flotation method to recover zinc oxide from a zinc oxide ore in Pu'er, Yunnan Province. The sodium sulfide was used as a vulcanizing agent and the octadecylamine was used as a collector. The original ore grade of zinc was 6.08. %, after one rough selection, three selections, three sweeps, the zinc concentrate grade was 37.21%, and the recovery rate was 64.97%. Amine collectors have good selectivity for lead and zinc, and their selection index is better than the vulcanization-xanthate method. However, the vulcanization-amine salt flotation method also has some shortcomings: it is sensitive to slime and soluble salts, and has poor selectivity to the ore-bearing gangue minerals, and the dosage of the chemicals is large. The actual production requires de-sludge and sulfuric acid cleaning and activation, which will cause a large loss of zinc metal and complicated process flow.
1.3 fatty acid collector flotation method
Fatty acids collector widely used in the flotation of silicate minerals, phosphates and other mineral oxide ores which can be used directly in the flotation of zinc oxide, it may also be used to remove reverse flotation concentrate carbonate Salt and sulphate to improve concentrate grade.
The French JMCases et al first applied the fatty acid process to the flotation of lead-zinc ore containing silicate gangue, and used this process to treat the Sanguninede lead oxide zinc ore by vulcanization-yellow medicine. The white lead ore was selected, and the silicate gangue mineral was inhibited by Na2CO3 and Na2SiO3. The diabase was directly floated with oleic acid, and finally the grade was 44.60% zinc concentrate, and the recovery rate was 84.50%. Ye Junjian et al. used a combination of fatty acid collectors FA-1 and GA-1 in the case of using butyl xanthate or amine collector GA-1 alone to have no collection effect on ore in the ore. When the collector is given a mineral grade of 8.90%, the zinc concentrate grade can be obtained by a rough selection of 22.59%, and the zinc recovery rate is 74.03%.
Although the study of fatty acid flotation lead oxide zinc ore began in the 1920s, fatty acid collectors have poor selectivity for gangue minerals and lead oxides for carbonate and sulfate gangue minerals. The zinc ore sorting effect is very poor, especially the lead-zinc-bearing ore with high iron content is more difficult, and it has not been widely used in industry.
1.4 Chelating agent flotation method
Chelating agent collectors have attracted much attention due to their high selectivity and strong ability to capture. Wang Lun et al. used the Pu'er County zinc oxide ore to carry out the organic chelating agent salicylaldehyde oxime-amine flotation test. A single flotation process was used to obtain a zinc concentrate with a grade of 37.07% and a recovery rate of 73.92%.
Tan Xin et al. studied the capture performance of CF collectors for smithsonite, leucite, calcite , dolomite, quartz and limonite. It was found that CF has good collection performance for smithsonite and leucite. The other side of the stone, dolomite, quartz, limonite is weak. When CF is used as a collector, sodium hexametaphosphate and zinc sulfate water glass can effectively inhibit the flotation of gangue minerals such as calcite.
It can effectively separate the diabase, leucite and gangue minerals in the slurry at normal temperature and natural pH. It does not require an alkaline environment like xanthate and amine collector, and the vulcanization process is subtracted. Increased operability, saving a lot of energy and sodium sulphide. It avoids the shortcomings of low selectivity of xanthate and amine collectors, low flotation index of lead-zinc ore, high consumption of chemicals and high operating cost. Due to the high price of chelating agent and relatively short development time, stability and theoretical research still need to be further improved, and it has not been widely used in production.
1.5 flocculation flotation method
The loss of lead oxide zinc ore in fine particles and slime is one of the main reasons for the low flotation index of lead-zinc ore. After the addition of the selective flocculant, the fine-grained lead-zinc minerals are agglomerated into larger-sized minerals, which improves the floatability and achieves the separation of fine-grained gangue minerals, effectively improving the recovery of lead-zinc metal. .
Yang et al. studied the possibility of selective flocculation of Lanping hydrozinc mine with anionic flocculant 2PAM30. The results show that the anionic flocculant 2PAM30 can be used to separate the hydrozinite and quartz by mixing with sodium hexametaphosphate and EDTA.
Han Wenjing conducted a laboratory medium-scale flocculation flotation study on a certain deep lead oxide zinc ore in Henan. The zinc oxide oxidation rate of the ore is 92.3%, the lead oxidation rate is 90.4%, and the primary slime is 16.8%. Carboxymethyl cellulose is used as a flocculant, and the principle of preferential flotation of lead and zinc is adopted. The experiment finally obtained lead and zinc concentrates with grades of 49.83% and 40.75%, respectively. The lead and zinc recovery rates were 42.26% and 81.64%, respectively. After the experiment was applied to the production, the zinc concentrate grade was above 30%, and the zinc recovery rate was 64%.
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