Research On The New And Clean Production Technology Of Dephosphorization Of Baosteel Steel Slag Magnetic Separation Tailing

Our country is the largest producer of iron and steel, and steel slag production is huge,but the comprehensive utilization ratio of steel slag is very low, only 30 to 40 percent. The best way to cause less even no steel slag emissions is internal recycling use in steel enterprises, which is also the best approach for the large amount of slag to be used.However, the problem of phosphorus enrichment prevents the internal recycling utilization of steel slag in steel enterprises. Therefore, steel slag dephosphorization is the key research topic of this slag being as alternative sintering flux. Based on the practice of chemical mineral processing, hydrometallurgy principle and exploration test studies, a new and clean production process of dephosphorization of Baosteel slag magnetic tailings,separating is proposed.The ammonium chloride leaching properties of steel slag magnetic separation tailings were studies. And the optimum technological conditions of ammonium chloride leaching of Baosteel slag magnetic tailings obtained are as follow as : the molar ratio of ammonium chloride and calcium oxide is 2:1; the particle size of the slag is 200 mashes; the leaching temperature is room temperature(20~25?); the ratio of liquid and solid(v/m) is 5:1;stirring strength is 380 r·min-1; and stirring time is 90 min. Under these conditions,leaching yield ratio of magnetic steel slag tailings can reach about 18.70%. And ammonium and carbon dioxide are added into the leaching slurry filtrate to calcification,and calcium carbonate obtained can be used as a raw material of sintering. And the concentration of ammonium chloride in the filtrate after calcification is adjusted, and this filtrate are returned to the cycle leaching of magnetic steel slag tailings.The optimum technological conditions of sulfuric acid leaching of the leached residues of ammonium chloride were as follow as :the mass fraction of sulfuric acid is10%; the particle size of the slag is 200 mashes; the leaching temperature is room temperature(20~25?); the ratio of liquid and solid(v/m) is 8:1; stirring strength is 230r·min-1; and stirring time is 90 min. Under these conditions, sulfuric acid leaching dephosphorization rate is about 85%. And the phosphorous content(P2O5) of the sulfuric acid leaching slag obtained is only 0.292%, and can be directly used as sintering raw material.The optimum technological conditions of dephosphorization of lime coagulation and sedimentation in acid leaching solution are that: the proportion of lime actual investments and theoretical inputs is 2.17:1(molar ratio); the reaction time is 60 min; the settlementtime after reaction is 3.5 h; the reaction temperature is room temperature(20~25?); and stirring strength is 230 r·min-1. Under these conditions, the dephosphorization ratio is more than 98%. And this dephosphorization residue can be further processed for other chemical products.The new cleaner production process of dephosphorizing Baosteel slag magnetic tailings can separate more phosphorus sintering raw material, so that steel slag can be achieved effective utilization, and waste emissions from the iron and steel enterprises are reduced. This process can be used for steel slag tailings comprehensive utilization technology of iron and steel enterprises.