The Comprehensive Utilization Of Tungstenslag

The methods of acid and alkali leaching alternately, which combined withphysical and chemical separations are used for the research of tungsten slagutilization, meanwhile the manufacturing of new types of gypsum whisker iscombined with the wastewater treatment of hydrometallurgy, which can achievemaximum use of tungsten slag resources and no waste discharge.Hydrochloric acid is selected to decompose tungsten slag. The optimalexperimental conditions are as follow: the concentration of hydrochloric acidis15%,the amount of hydrochloric acid is1.5times as the theoretical amount,the reaction temperature is90℃, the reaction time is4hour. Under thiscondition, the leaching rates of Ca, Fe, Mn are more than90%, the retention rateof niobium and tantalum are85.6%and92.8%.After the acid hydrolyzateneutralized by calcium hydroxide by multi-steps,the recoveries of P, Fe, Mn aremore than90%.The acid hydrolyzate is neutralized by calcium hydroxide by multi-steps.Calcium hydrogen phosphate, iron hydroxide and manganese hydroxideprecipitates are formed separately from the liquid phase, produce appropriateuseful product. The pH value for dicalcium phosphate precipitation is controlled，withinthe range of1.2to5.5. Reaction temperature is45℃, and rapid stirring isneeded to avoid reactant wrapped by product, otherwise the content of primaryproduct will be decreased and the raw material will be wasted. The content ofcalcium hydrogen phosphate in product is87.2%.The optimum conditions of divalent iron oxidation and precipitation areas follows: reaction temperature is70℃, pH is above6. Maintain a stable pH,the iron can be almost completely separated, and without any loss of manganese.The content of ferric oxide in precipitate is92.6%.The manganese ions are recovered within the pH range6.5~11, themanganese dioxide content of the obtained precipitate is85.49%.The optimal reaction conditions of gypsum whisker preparation process are:the concentration of sulfuric acid is50%, the concentration of CaCl2is1.5~2mol/L, heated these liquids over80℃and rapid mixed under constant stirring,the addition time is10min, the concentration of crystalline improver CPAM is8mg/L, the combination of microwave and oven are used to dry the whiskersquickly. Under these conditions, long rod-like whiskers, which whiteness are upto95%and have good dispersibility, can be obtained.