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Meishan iron ore beneficiation plant is designed to process ore of 2.5 million t, actually large-scale concentrator 1.65 million t, about 22% to 23% tailings separated from the ore every year, mainly from the tailings re-election operation The tail of the vibrating chute and the jig. Among them, +0.3mm is a dry coarse-grained tailings (commonly known as waste rock); -0.3mm is a wet fine-grained tailings (called tailings), which is mainly from the concentrated cone overflow of 2~0mm grain-grade ore; 2~ 0mm particle size jigging before re-concentration bucket overflow; magnetic separation concentrate permanent magnet dewatering tank overflow; 12 ~ 0mm grain grade concentrate grader overflow; tailings classifier overflow. The tailings yield is about 7% (accounting for the original ore), and the iron content is between 20% and 23%. The main components are magnetite, siderite, quartz , calcite , pyrite ore and kaolin . Table 1. Among them, the -0.074mm particle size accounts for about 80%, the iron is mainly distributed in the -0.074mm particle size, and the magnetic iron and iron carbonate content are 28.73% and 35.35%, respectively.
Table 1 Mineral composition of tailings (%)
mineral
magnetite
Siderite
Hematite
Pyrite
Calcite
Kaolinite
quartz
Feldspar
Apatite
dolomite
Quality score
10.3
16.05
5.6
5.2
13.42
13.72
15.42
7.0
1.0
9.7
In August 1991, the concentrator established a tailings re-election system to recover iron minerals in fine tailings by magnetic separation, and re-elect tailings with a strong magnetic separator (field strength of 191kA/m) (1 Times). After production, qualified iron concentrate with 57.8% iron and 0.4% sulfur can be obtained. The tailing grade can be reduced to below 19.39%, and the total tailings grade is reduced by 2%. According to the annual processing of 1.8 million tons of raw ore, it can recover 0.9 million tons of iron concentrate from abandoned tailings every year, with an annual economic benefit of more than 1.5 million yuan.