熔融NaOH分解橄榄石型硅酸盐的反应机理

采用熔融NaOH分解Mg2SiO4和MgNiSiO4,采用拉曼光谱对碱熔融过程进行在线检测,利用X射线衍射仪和红外光谱仪等分析碱融后的水浸渣,研究硅酸盐在熔融碱中的分解机理。结果表明:NaOH对Mg2SiO4中Mg离子的释放是逐次进行的,其中间产物为Na2MgSiO4;MgNiSiO4在碱熔融分解过程中,Ni离子优先于Mg离子从硅酸盐阵列中释放;镁和镍橄榄石型硅酸盐中的Mg—O和Ni—O最终都可以被Na—O替换,生成Na4SiO4。

Reaction mechanisms of decomposition of magnesium nickel silicate by alkali fusion using NaOH

The decomposition of forsterite and magnesium-nickel silicate was undertaken by alkali fusion using NaOH at elevated temperatures.Raman spectra were measured for the reactions between the silicates and sodium hydroxide in-situ during the alkali fusion process.Meanwhile,the water-leaching residue of the fusion products was characterized by X-ray diffractometry and infrared spectroscopy.The results show that the magnesium ions in Mg2SiO4 can be liberated from the silica arrays successively by aggression of sodium hydroxide,giving rise to Na2MgSiO4 as an intermediate;whereas nickel ions seem to be released much easier from the arrays of MgNiSiO4 than magnesium ions,and move out from their array sites prior to magnesium ions.The bindings between Mg-O and Ni-O in their silicates can be substituted by Na-O completely,and Na4SiO4 is one of the final products for the alkali fusion process.