Research On Removing Sulfur From Pyrite Slag With Microorganism

The accumulations of pyrite slag could result in occupancy of great deal of land as well as serious pollution of the environment. Pyrite slag should be exploited and utilized reasonably. In this way, the wastes could become useful resource and the environment could be protected.There are high contents of the iron in pyrite slag, from which the iron concentrate could be recycled. However, the characteristic of pyrite slag is sulfur content that is the harmful impurities of iron-making raw materials. The slag with the sulfur content less than 0.5% could be used as the iron-making raw materials.In the present paper, the study was done to remove sulfur from North Korean pyrite slag by microorganism method .The microorganism is a thiobacillus ferrous (T.f).To remove sulfur from North Korean pyrite slag, several influence factors were concerned, such as bacteria sorts, cultivation time, pulp density, slag particle size, nitrogen source and catalyst etc. Through the experiment of single factor, the conclusions were gained. The T.f. bacteria, which directly abstracted from North Korean pyrite slag was used to remove sulfur. Then, enriched it, the rate of desulphurization was raised by tamed T.f. bacteria to deal with North Korean pyrite slag. When the bacteria were cultivated in such conditions: incubating time of 72 hours and pulp density of 80g/L and nitrogen source-CNH₄)₂SO₄ of lg/L, AgNO₃ catalyst of 0.05g/L, the effect of desulphurization appeared best. After six days' treating, the sulfur content was lower than 0.5%, reduced from 1.17% to 0.47% and the rate of desulphurization was 59.8%.North Korean iron concentrate, which the content of the iron was 65.15%, the contents of the sulfur was 1.14%, could be gained by magnetization. In desulphurization process of North Korean iron concentrate when the treating condition was the same as treating North Korean pyrite slag, after five days, the sulfur content was reduced from 1.14% to 0.45% and the rate of desulphurization was 60.5%, which was suitable for smelting. The time of desulphurization was cut down one day.The experiments results showed, it was more economical and feasible to remove sulfur from North Korean iron concentrate than to remove sulfur from North Korean pyrite slag, and the effect was better. In the study, the measure of further desulphurization of North Korean iron concentrate was found. It was continuing operated and replaced the culture medium once every two days, disposed for four days, the sulfur content could be reduced from 1.14% to 0.44%, and the rate of desulphurization was 61.4%. the conclusion showed, The time of desulphurization was cut short one day again, and the effect of desulphurization was much better.