With the non-ferrous metal industry rapidly advancing, the efficient use of lead-zinc mineral resources is becoming increasingly important. Particularly for complex lead-zinc sulfide ores, with their varied mineral composition, inconsistent particle sizes, and high oxidation rates, traditional grinding and flotation methods fall short in achieving efficient separation and recovery. Consequently, it is crucial to explore and implement more efficient, eco-friendly mineral processing techniques. This article focuses on a complex lead-zinc sulfide mine to examine the application of a staged grinding and flotation process in this type of ore, aiming to inform the beneficiation of similar ores.
The chemical multi-element analysis of a complex lead-zinc sulfide ore shows that the valuable components in the ore are mainly Pb and Zn, while also containing high levels of S, Fe, and SiO2. In terms of mineral composition, it mainly includes sphalerite (containing iron sphalerite), galena, pyrrhotite, pyrite, quartz, chlorite, montmorillonite, and mica. The statistical analysis of the particle size distribution of galena and sphalerite shows that galena mainly exists in the form of coarse particles, while sphalerite is mainly distributed in fine particles.
Stage grinding and flotation process is a method of designing grinding and flotation processes based on the particle size and monomer dissociation degree of minerals in the ore. The core idea of this process is "early recovery", which means recovering minerals that are easy to grind and float as early as possible during the grinding process, thereby improving the efficiency and selectivity of the entire process. For lead and zinc minerals with uneven particle size distribution, the stage grinding and flotation process can effectively achieve the separation and enrichment of lead and zinc minerals.
Based on the analysis of ore properties, this study conducted comparative experiments between the step grinding and selection process and the traditional grinding and flotation process. In the experiment, it was found that the step grinding and step selection process can obtain higher grade and recovery rate of lead coarse concentrate in the first stage of grinding flotation (rapid lead flotation), and has little effect on zinc flotation. Therefore, the step grinding step selection process was determined, and detailed condition experiments were conducted on this basis.
Lead selection Na2S dosage test
Adding Na2S can activate the flotation of lead-zinc minerals in sulfide lead-zinc ores with high oxidation rates. By controlling the sulfurization time and Na2S dosage, the flotation efficiency of lead-zinc minerals can be significantly improved. The experimental results indicate that the appropriate dosage of Na2S is 200 g/t and the sulfurization time is 7 minutes.
Type and dosage test of collector
Ding Huang Yao, Ding ammonium black medicine, ethyl sulfide nitrogen, and HQ77 were selected as collectors for the experiment. The results showed that the comprehensive recovery index of HQ77 was significantly better than the other three collectors. Further experiments on the dosage of HQ77 showed that optimal lead zinc flotation indicators can be obtained when the dosage of HQ77 is 200 g/t.
Type and dosage test of inhibitors
In the lead flotation process, ZnSO4 and Na2SO3 act as inhibitors, which can effectively suppress zinc sulfide minerals. By adjusting the dosage of the combination inhibitor, it is possible to simultaneously obtain lead concentrate and zinc concentrate with higher grade and recovery rate. The appropriate dosages of ZnSO4 and Na2SO3 were determined to be 800 g/t and 300 g/t, respectively, through experiments.
After completing the condition test, laboratory small-scale flotation closed-circuit tests were conducted for lead flotation (two roughing, three refining, and two sweeping) and zinc flotation (one roughing, two refining, and two sweeping). The experimental results show that lead concentrate with a lead grade of 60.05% and a lead recovery rate of 89.63%, as well as zinc concentrate with a zinc grade of 47.01% and a zinc recovery rate of 88.14%, can be obtained, achieving efficient recovery of lead and zinc.
