The beneficiation methods of tin ore are different due to the difference of symbiotic and associated minerals. This article introduces the beneficiation methods of tin ore, cassiterite polymetallic sulfide ore, and placer tin ore.
The density of tin ore is higher than that of paragenetic minerals. Therefore, for a long time, gravity beneficiation was the main method of tin ore beneficiation. However, as the number of easy-to-select tin ores became less and less, the particle size of cassiterite in the ore was getting smaller and smaller. Therefore, Cassiterite flotation process appeared.
Since various iron oxide minerals often exist in tin minerals, such as magnetite, hematite and limonite, these minerals cannot be separated from cassiterite by flotation and gravity separation, so in recent years, Magnetic separation has appeared in the tin ore beneficiation process.
Tin ore is commonly used in the combined flotation-heavy beneficiation method. The process flow is: raw ore is crushed to 20mm, one-stage closed-circuit grinding to 0.074mm (200 mesh) accounts for 60% to 65%, mixed flotation, one coarse, two sweeps and one fine; copper sulfur Separation grinding to 0.074mm accounts for 95% 1 roughing 2 sweeping 3 fines to produce copper concentrate and sulfur concentrate; mixed flotation tailings are re-selected for sulfide and then re-selected.
The ore contains high-grade tin, lead, antimony and zinc, and contains sulfur, arsenic, cadmium, indium, silver and gold, which can be comprehensively recovered as associated elements and rare and precious metal elements. The ore has many types of minerals and its components are very complex, so the difficulty of beneficiation is also very high.
After key scientific and technological breakthroughs, the expansion test was carried out using the two principles of magnetic-floating-heavy and magnetic-heavy-floating-heavy, and a good sorting index was obtained.
The magnetic-flotation-gravity separation method is as follows: the sulfide ore flotation adopts the preferential mixed flotation separation process, and the recovery rates of tin, lead, antimony and zinc are 78.11%, 85.59%, 82.63% and 81.65% respectively.
After the raw ore is crushed to -20mm, it is screened and divided into two grades of 20-4 and 4-0mm, and 20-4mm enters the dense medium cyclone for pre-selection. The heavy product of the dense medium cyclone is pre-selected by jigging after a stage of rod milling, and the jigging tailings are screened with a 2mm vibrating screen to remove +2mm as waste tailings, and -2mm is sent to the shaker for separation. The mixed flotation tailings are sorted by shaking table to produce qualified tin concentrate; the mixed flotation concentrate is then finely ground for lead-zinc separation flotation, and lead-antimony concentrate and zinc concentrate are produced respectively. The gravitational slime enters the Φ300mm cyclone, the overflow is then passed through the Φ125 and Φ75mm hydrocyclones to remove the fine mud, the sand is concentrated, flotation and desulfurized, and then the cassiterite flotation is carried out.
Xinlu Tin Mine is one of the main tin mines affiliated to Guangxi Pinggui Mining Bureau. The former has high grade and large reserves, and is distributed in massive, cystic and beaded shapes; the latter has low grade, wide distribution, and complex ore bodies.
Since the intercalation characteristics of cassiterite in particle sizes larger than 5mm and smaller than 5mm are somewhat different, 5mm is used as the boundary for coarse and fine separation.
The coarse sand of +5 mm is separated by two jiggings after passing through the rod mill, and the tailings of the first jigging are swept by a shaking table to obtain a coarse concentrate with a tin grade of 8% to 9% and enter the secondary mill.
The fine sand of -5mm is classified with a Φ600mm cyclone, and its settling is separated by jigging twice, and the overflow is then classified with a Φ400mm cyclone and separated by a shaking table.
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