Studies On Immobilization Of Zinc In Tailings By Composite Modified Bentonite

In this study, the tailings was collected from mining industry, GuangXi Hechi. The tailings’physical and chemical properties were been researched. To find cost-effective fixative, leaching experiment was chose for this paper.By physical and chemical research, it indicated that the content of Zinc was highest; and the tailings has a good capacity to acid solution, because it can raise vary level of acidic solution to neutral or alkalescent within48hours. Under laboratory conditions, leaching experiments for tailings showed that soaking liquid acidity and soaking time has some effect on leaching quantity of zinc.Bentonite from Guangxi Binyang was used as raw material. Two different kinds of compound-modified bentonite were made by bentonite from Binyang, and the immobilization ability of modified bentonite under different situation were researched in this paper. In this paper, we mixed chitosan and ethanediamine or SDS with bentonite, to made two different kinds of organobentonite, and studied the fixated rate under different conditions. Besides, the best modified condition of SDS modification were studied. The results indicated that MB showed better results than B, when in a relatively acidic environment. The immobilization ratio of Zn in tailings was57～83%. The single factor experiment showed that the optimum immobilization conditions were:MB adding1.5g/50g; reaction temperature35℃; pH≥4.0; stable time≥4hours. The orthogonal experiment showed that pH was the most important condition, and other results were:MB adding1.5g; reaction temperature30℃; pH=5.6. the same as the single factor experiments, and the surface structure of original bentonite and modified bentonite was characterized by SEM and XRD, the results indicated that chitosan and ethanediamine were incorporated onto bentonite and intercalated into bentonite partially; GB was prepared by adding SDS to calcined bentonite, GB also showed better results than B, the best calcine temperature is300℃and the appropriate dosage of SDS is10percent of bentonite. The single factor experiment showed some results as follow:the economic dosing quantity of GB was1.5g; the fixed effect was stable between25℃and40℃; fixed process achieve stable in4hours; and GB showed good results even in a relatively acidic environment with pH value of4. Through XRD, we can know that SDS intercalated into bentonite successfully.