利用钾长石合成雪硅钙石纳米粉体的反应机理研究  

Synthesis of Tobermorite Nano-scale Powder from Potassium Feldspar:Reactive Mechanism Research

作　　者：刘贺[1] 马鸿文[1] 聂轶苗[1] 王蕾[1] 

机构地区：[1]中国地质大学矿物材料国家专业实验室,北京100083

出　　处：《现代地质》2006年第2期347-353,共7页Geoscience

基　　金：中国地质大学矿物材料国家专业实验室开放基金项目(04103)

摘　　要：采用CaO为助剂，在水热条件下分解钾长石，进而合成雪硅钙石。影响反应的主要因素为：n（CaO）／n（SiO2＋AlO1．5）、晶化温度和晶化时间等。在n（CaO）／n（SiO2＋AlO1.5）为0．75-1．00、晶化温度为230-250℃、晶化时间为5-8h的条件下，可以合成结晶良好的雪硅钙石晶体。反应机理分析表明：在钾长石一氧化钙的水热体系中，钾长石的分解并不是简单的离子交换作用或铝硅酸盐解聚作用，而是在碱金属离子与水作用的基础上，反应物中H^＋与矿物表面的碱金属离子K^＋、Na^＋、Ca^＋作用，首先形成表面富硅贫铝的前驱聚合体（SiO2·nH2O）；然后这些前驱聚合体分解，与溶液中的Ca^2＋作用，生成C-S-H凝胶和水钙铝榴石；随着反应时间的延长，C-S-H凝胶和水钙铝榴石进一步转变为雪硅钙石。Potassium feldspar was hydrothermally decomposed with CaO as an additive, and then tobermorite nano-scale powder was synthesized. The effective factors on the synthesizing reaction were the mole ratio of CaO/（ SiO2 ＋ AlO1.5 ）, reaction temperature and reaction time. The experimental results showed the tobermorite was crystallized well with the mole ratio of CaO/（ SiO2 ＋ AlO1.5 ） in the range of 0. 75 to 1.00, at the reaction temperature of 230 to 250 ℃ for 5 to 8 hours. The research data obtained in this study demonstrate that the reactive mechanism of the potassium feldspar＇s dissolution cannot be explained solely on the basis of ion exchange or aluminosilicate depolymerization reaction. The dissolution of potassium feldspar and the crystallization of tobermorite in hydrothermal system are considered possibly as a three-step process. At first, the potassium feldspar decomposes and gives rise to Si-rich and Al-deficient surface precursor complexes, secondly, the precursor complexes （SiO2·nH2O） decompose and further to form C-S-H gel and hydrogamet phases, and at last, the C-S-H gel and hydrogamet are converted into the tobermorite.

关 键 词：低温水热法 钾长石 雪硅钙石 反应机理 

分 类 号：P575[天文地球—矿物学] P579[天文地球—地质学]