伊利石中硅的热化学活化与脱除

Thermochemical Activation of Silicon in Illite and Its Removal

伊利石是铝土矿中主要含硅矿物之一。TG -DTA、XRD和IR综合研究表明 ,在热作用下 ,伊利石在5 0 0～ 70 0℃脱去羟基 ,在 110 0℃左右结构发生非晶质转化 ,层状结构中的硅被活化为无定形SiO2 。根据无定形SiO2 易溶于稀碱溶液的特性 ,开发了伊利石热化学活化 -碱浸脱硅新工艺。当热活化温度 110 0～ 115 0℃ ,热活化时间 90～ 12 0min ,碱浸出温度 95℃ ,Na2 OK=(12 0～ 15 0 )g/L ,浸出时间 90～ 12 0min时 ,可获得 4 5 %左右的脱硅率。XRD分析结果表明 ,热活化生成的无定形SiO2 溶于NaOH溶液被脱除 ,但碱浸过程中生成水合铝硅酸钠导致脱硅率较低。矿石中含有的天然α -SiO2 在热化学活化、碱浸过程所表现出的惰性也使得总脱硅率降低。

Illite is one of the major silicon containing minerals in bauxite ores. Comprehensive TG-DTA, XRD and IR study results show that the OH groups will split off from illite at 500 ℃～ 700 ℃ and at about 1100 ℃,the illite structure will undergo a amorphous change when the silicon in the layers will be transformed into amorphous substance. A desilication process for illite by thermochemical activation-alkali leaching is therefore developed on the basis of the character that amorphous silica is alkali soluble. A desiliation rate of about 45% can be obtained under the following operation conditions: activation temperature of 1100～ 1150 ℃,activation time of 90～ 120 min,alkali leaching temperature of about 95 ℃,concentration of caustic soda (Na 2OK) of 120～ 150 g/L,and leaching time of 90～ 120 min,XRD analysis shows that amporphous SiO 2 generated by activation dissolves in NaOH solution, where it is removed. However the desilication rate is low due to the formation of sodium hydroaluminosilicates in alkali leaching. Moreover, The inertness of natural α-SiO 2 exhibited in the thermochemical activation and alkali leaching also leads to reduced overall desilication rate.