Preparation And Application Of Silicate Coagulant From Iron And Steel Metallurgical Slag

Blast furnace slag water quenching is one of iron and steel metallurgy wasteresidue.Because of its special chemical composition and pHase structure, can be used asraw material for water treatment chemicals.Preparation of silicate coagulant has not beenstudied by water quenching slag.Water quenching slag was explored as raw material to prepare poly-silicate aluminumferric sulfate (PSSAF) coagulant and poly-silicate aluminum ferric sulfate (SSAF).Theresults are as follows:(1)Acid leaching of iron and aluminum ions show:the leaching rate of aluminum、iron、silicon were3.37%,28%and0.77%in condition of Na2CO3/water quenching slagmass ratio was0.3、calcination temperature was900℃,and holding time was2h bycalcination,acid slag ratio was25:1,the concentration of H2SO4was6mol/L，the leachingtemperature was100℃,the leaching time was60min,the result of XRD and SEM show thatpHase has changed;(2)Alkali leaching process show:the leaching rate of silicon were60%,theconcentration of silicon was9265mg/L respectively in condition of the concentration ofNaOH was5.5mol/L, leaching time was5min,alkali slag ratio was25:1,the leachingtemperature was80℃;(3)Study on preparation and application of poly-silicate coagulant show:the effect ofcoagulant was best in conditions of （Fe+Al)/Si molar ratio was0.53,aging time was30min,the removal efficiencies of turbidity and COD was91.5%and60.23%;and the heremoval efficiencies of turbidity and COD was99.3%and91.5%for effluent from cokingplant in condition of best dosage of2.4mL/L,PSSAF with pH of6.5~8.5;(4)Contrasting the flocculation efficiency of PSSAF with M180,polymeric aluminumferric chloride(PFAC) and poly-ferric sulfate (PFS),the result show:the sequence ofcoagulation was PSSAF�'M180�'PFAC�'PFS.The removal efficiencies of turbidity and COD was98.9%and74.5%by PSSAF.Cost accounting shows that PSSAF cost slightlyhigher...