Studies On The Treatment Of Zinc In Tailings Leaching Solution By Composite Modified Fly Ash

A tailings in Hechi, Guangxi piled up a lot of tailings, it’s often under acid rain. Heavy metals in tailings can easily be leached out into the surrounding environment. This will lead to a high risk of ecological environment. The purpose of this paper is to find an economical and highly efficient adsorption material, which is used in tailings treatment to reduce the leaching amount of heavy metals in tailings.In this paper, a new modified fly ash (MFA) was prepared by solution method with the fly ash (FA) as raw material and two different organic compounds hexadecyl trimethyl ammonium bromide and NH4Cl as modifiers. The adsorption performance of modified fly ash was determined by the simulation tailings leaching solution experimental, and the modification mechanism was analyzed. In the actual tailings leaching solution, the optimum conditions optimized by single factor experiment and orthogonal experiments. The experimental results show that:In the simulation of tailings leaching solution experiment, the single factor experiment results showed that the highest removal rate of Zn by the MFA was 96.8%, the optimum conditions of MAF were:MAF adding 2.0g; reaction time 40min; reaction temperature of 25 ℃; pH≥ 4.0. The results of isothermal adsorption experiment showed that the adsorption process of modified fly ash on Zn were finely fitted to the Langmuir equation and the Freundlich equation, and it was single molecule layer adsorption. The saturated adsorption capacity of the MFA was 17.39mg/g, adsorption capacity were much higher than that by the original fly ash. The characterization results of SEM, XRD and IR and the modification mechanism showed that the fly ash was changed by the composite modification. On the surface of fly ash, the vitreous structure was destroyed, the specific surface area became larger, and a large number of Al and Si active groups appeared. Adsorption capacity of fly ash increased with a reasonable explanation.In the experiment of actual tailings leaching solution,the highest removal rate of Zn by the MFA was 91.9%.The effect of pH and temperature on the use of MFA was similar to the simulation experimental results. The reaction time in the experiment of actual tailings leaching solution was much longer than the simulation experiment,it was basically stable in 8 hours.Orthogonal experimental results showed that, adding amount was the most important factor to affect the adsorption effect, and the effect of pH on removal rate was the least, the optimum conditions optimized by orthogonal experiments were: MAF adding 2.5g/50g tailings; reaction temperature of 25 ℃; pH≥ 4.0. The simulated acid rain experiments showed that the MFA was suitable for use in the falling area of acid rain.