二氧化硅在铝酸钠溶液中的反应行为

采用两种纯硅矿物(白炭黑和高岭土)为原料, 研究二氧化硅在铝酸钠溶液中的反应行为。结果表明: 硅矿物在铝酸钠溶液中的反应行为包括硅矿物分解和硅渣析出两个过程, 两者之间存在动态平衡, 温度升高, 硅矿物反应率升高; 在高温(280 ℃)条件下, 影响硅矿物反应率的主要因素是溶液游离Na₂O_k浓度, 随着游离Na₂O_k的升高, 硅矿物反应率下降; 溶液中氧化铝浓度对硅矿物反应率影响不大; 溶液游离碱和氧化铝浓度升高可阻碍硅渣析出反应的进行, 不利于钠硅渣的形成。研究结果可为低铝硅比铝土矿的铝硅分离提供理论依据。

Reaction Behavior of Silica in Sodium Aluminate Solution

Using two kinds of pure silicon minerals(silica and kaolin) as raw material, the reaction behavior of silica in sodium aluminate solution was investigated. The results showed that the reaction behavior of silicon minerals in sodium aluminate solution included two processes of decomposition of silicon minerals and precipitation of silica residue, between which dynamic equilibrium occurred. The reaction rate of silicon minerals increased with the increase of temperature. Under the condition of high temperature(280 ℃), the main factor which affected reaction rate of silicon minerals was free Na_2O_k concentration in solution. The reaction rate of silicon minerals decreased with the increase of free Na_2O_k concentration. Alumina concentration in solution had little influence on the reaction rate of silicon minerals. The increase of free alkali and alumina concentration in solution can resist the precipitation reaction of silica residue, which go against the formation of sodium and silica residues. The results provided theoretical references for the separation of aluminium and silicon in bauxite with low Al/Si ratio.