Fundamental Research Of Comprehensive Use Of Boron Mud By Alkali Fusion Method

Boron mud is a kind of alkaline industrial waste produced from the production of borax, it is seriously harmful to the crops and the ecological environment. If it can be effectively used, there will be considerable economic benefits and social benefits.In this paper, the technology conditions of the process and kinetics were studied through the process of alkali fusion roasting, dissolution, filtration, carbonation. The main research content is as follows:(1) On the basis of single factor and orthogonal experiment, the molten alkali temperature, reaction time, mass ratio of alkaline were investigated in the roasting process according to silicon dioxide extraction rate. It is found that the best roasting process condition is to make it roasted at550℃for20min with the mass ratio of alkaline to ore (mass ratio)1.75:1.(2) Through the dynamic analysis of boron and silicon extraction in the process, it is known that the reaction process of the two are the same kind, both reactions conform to the shrinking core model with the production of solid product layer and the reaction process can be divided into two phases, the first stage of the reaction time is0-20min, the second stage of the reaction time is20-50min. The first stage of the reaction is controlled by interface reaction; the second stage is controlled by product layer diffusion. As shown in the paper, during the temperature400℃～550℃with the mass ratio of alkali to boron mud1.75:1, the Si extraction dynamics equations of the two stages are respectively, the activation energy of the two phases are44.78kJ·mol-1and15.94k·J-mol-1respectively; the boron extraction dynamics equations of the two stages are respectively, the activation energy of the two stages are41.74kJ·mol-1, the second phase is15.43kJ·mol-1respectively.(3) The process and the reaction kinetics of the preparation of white carbon black were studied in the paper. As found in the study, the final pH value of the first carbonation process is11.5, the optimum process conditions of carbon process are as follows:reaction temperature60℃, the concentration of sodium silicate solution1.Omol·L-1, and under this condition, the reaction rate can reach86.44%.Dynamics of carbon process shows that carbon extraction process is mainly controlled by the secondary chemical reaction, which is divided into three stages. When the concentration of sodium silicate is1mol·L-1, the temperature is60℃, the reaction rate constant of the three stages are K1=0.0064L·h·mol-1, K2=3.178L·h·mol-1, K3=1.130L·h·mol-1respectively.