Treatment The Ion Exchange Water Of Vanadium Extraction From Stone Coal And Separation-recovery Valuable Metals

At present, the acid wastewater containing variety of heavy metal is produced inthe process of vanadium extraction from stone coal, it can cause environmentalpollution seriously and waste valuable metal resources. Therefore, effective extractionof valuable metals becomes focus from the wastewater. Referring literatureinfornation and according to the analyzing results of vanadium plant wastewater, thesimulated wastewater was regarded as raw materials and treated by two-step chemicalprecipitation. The valuable metals in the wastewater were recovered by ammonialeaching, alkaline leaching and oxidation separation. And then water maybe recycled.The wastewater was treated via two-step chemical precipitation which includesiron precipitation and precipitation of other metals. Firstly, pH value in the range of3.0-3.2was adjusted by lime milk to precipitate iron. Secondly, sodium carbonate wasadded to adjust to pH8.8-9.0and other metals were precipited from the wastwater.The result showed that wastewater could meet the discharge standards.The compositions of the first-step silt mainly contained calcium sulfate and ferrichydroxide. Calcium sulfate with purity of98.2%was obtained through theacid-soluble separated, and96.1%Fe2O3with a yield83%was obtained by precipitateiron and calcine from the filtrate.The second step silt exist the metal hydroxides and basic carbonates. Copper, zincand cadmium leaching by ammonia, single factor test and orthogonal test conditionswere studied, the optimum leaching conditions were determined: ammoniaconcentration of5mol·L-1, liquid-solid ratio of16:1, temperature of50, time of75min.The ammonia immersion use zinc replacement of copper and cadmium, the zincpowder dosage and the replacement time of displacement effect preliminary werestudied. The zinc powder amount of2times of the theoretical, time of15min,obtained98.3%copperpowder and90.5%of the sponge cadmium. Concentrated byevaporation, crystallization recovery of93.6%ZnSO4·7H2O. Copper, zinc andcadmium recoveries were91%,87.4%and84.1%.Study of the NaOH concentration, liquid to solid ratio, temperature and time forthe NaOH dip aluminum optimum conditions, the best conditions: NaOHconcentration of2mol·L-1, the ratio of liquid to solid of9:1, temperature of90,leaching75min. And Al(OH)3purity of88.05%was prepared. Aluminum recoveryrate was93.04%. By comparing with hydrogen peroxide, ammonium persulfate and sodiumhypochlorite oxidation effect for Cr(III), the best oxidizing agent is sodiumhypochlorite, and under the conditions of the pH value of11, temperature of60,oxidizing30min, oxidation rate reached95%. Cr() solution prepared lead chromatewhich contain leaded65.1%and chromium14.8%. This process also recyclesmanganese dioxide products which contain manganese60.5%. The chromium andmanganese recoveries were87.4%,81%.Magnesium in the silt after the purification of the impurity were preparated basicmagnesium carbonate products which content MgO of40.7%. Magnesium recoverywas89.5%.By expanding the experiment proved that the wastewater treat by two-stepchemical precipitation and valuable metals recovery process is feasible, has industrialapplication value.