Studies On Immobilization Of Zinc In Tailings By Organic Composite Modified Sodium-Bentonite

There are a large number of cumulate tailings in Guangxi, a large sum of heavy metal will leaching in condition of frequent acid rain landing, then it will pose threat to water, soil and human health. In this study, one tin tore of Hechi city in Guangxi was taken as research object. Aiming at the actual situation of acid rain landing in the locality, this study planned to exploit fixatives not only could be used in acidic condition, but also be cost effective, So the content of Zn in lixivium of tailings could be reduced, then local ecological environment could be protected.Urea-chitosan and EDTA-chitosan were used to modified bentonite, The research took time and pH as variables to study leaching behavior of Zn in tailings. Single-factor experiment took dosage, time, pH and temperature as variables. Orthogonal experiment took dosage, pH and temperature as variables, rely on above experiments, the influence of factors to bentonite fixing Zn in tailings could be explored and fixed condition also be optimized, all kinds of bentonite were characterized by scanning electron microscope (SEM), infrared radiation (IR) and X-Ray diffraction (XRD). The above experiments insisted on the following conclusions.1) pH was a vital factor to the concentration of Zinc in lixivium, the stronger acidity of leaching solution was, the higher leaching concentration of Zn was. Leaching time also had some effects on the concentration of Zn in lixivium.2) the fixed rate of bentonite compound modified by urea and chitosan summed up to 86%. The optimum immobilization conditions were:adding amount 1.5g/50g tailings, reaction temperature was 25℃, pH was 4.5, stable time was 3 hours. The fixed rate of bentonite compound modified by EDTA and chitosan summed up to 93%. The optimum immobilization conditions were: adding amount 6 g/50g tailings, reaction temperature was 35℃, pH was 4.5, stable time was 2 hours. The orthogonal experiment showed that pH was the most important condition. The best fixed condition was consistent with orthogonal experiment. These two kinds of modified bentonite all can be used in areas with frequent acid rain.3) The modifiers of these two kinds of modified bentonite were partly loaded to surface of bentonite, and partly intercalated to interlamination of bentonite.