第45卷第11期2017年11月
硅酸盐学报Vol. 45,No. 11
November,2017 JOURNAL OF THE CHINESE CERAMIC SOCIETY
https://www.doczj.com/doc/4c7821391.html, DOI:10.14062/j.issn.0454-5648.2017.11.17 硅酸钾碱液水热合成针状硅灰石反应历程
罗征1,2,马鸿文1,杨静1
(1. 中国地质大学(北京)材料科学与工程学院,北京 100083;
2. 昊青新材(北京)技术有限公司,北京 100083)
摘要:利用钾长石–KOH–H2O体系分解反应所得硅酸钾碱液合成针状硬硅钙石,用作合成硅灰石的前驱体。采用OLI Analyzer 9.2软件模拟K2O–CaO–SiO2–H2O体系化学平衡,预测了合成硬硅钙石的初始CaO/SiO2摩尔比、反应温度和液固比范围。在此基础上通过单因素实验,确定了合成硬硅钙石的优化条件。反应历程为:水合硅酸钙→雪硅钙石→雪硅钙石+硬硅钙石→硬硅钙石。合成的硅灰石保持了硬硅钙石的针状形貌,分散较均匀,长约10~15μm,直径约300nm,长径比约40,符合建材行业一级品标准。
关键词:钾长石;硬硅钙石;硅灰石;绿色合成
中图分类号:TQ443.5 文献标志码:A 文章编号:0454–5648(2017)11–1679–07
网络出版时间:2017–10–09 13:56:00 网络出版地址:https://www.doczj.com/doc/4c7821391.html,/kcms/detail/11.2310.TQ.20171009.1356.009.html Hydrothermal Synthesis of Acicular Wollastonite from Potassium Silicate Solution
LUO Zheng1,2, MA Hongwen1, YANG Jing1
(1. School of Materials Science and Technology, China university of Geosciences, Beijing 100083, China;
2. Bluesky Technology Corporation, Beijing 100083, China)
Abstract: Xonotlite, as a precursor for synthesizing acicular wollastonite, was synthesized using K-feldspar alkai-leaching filtrate as a silicon source. The chemical equilibrium in the system of K2O–CaO–SiO2–H2O was simulated by a thermodynamical software named OLI Analyzer 9.2, predicting the effects of initial CaO/SiO2 molar ratio, reaction temperature, and liquid-solid ratio as well. The optimal conditions and reaction process of synthesis of xonotlite were determined at the predicted parameters. The reaction process of xonotlite from the alkai-leaching filtrate is calcium silicate hydrate → tobermorite → tobermorite + xonotlite → xonotlite. The size of resultant acicular wollastonite is 10–15 μm in length and approximately 300 nm in diameter, and the product is conformed as a prime standard material in building materials industry.
Keywords: K-feldspar; xonotlite; wollastonite; green synthesis
硅灰石是一种链状偏硅酸钙矿物,化学式为CaSiO3,理论组成(w B%)为:CaO,48.3%;SiO2,51.7%。天然硅灰石成分复杂,伴生杂质矿物多,且由于不同产地的成矿条件差别,导致硅灰石产品纯度波动大、性能不稳定、白度低,应用受到一定限制。合成硅灰石则具有更大的选择性和可控性,有着更为优良的性能和广泛的应用范围[1–3]。
硅灰石产品分为高长径比硅灰石和磨细硅灰石两大类。前者属于高档产品,主要利用其针状物理机械性能,广泛的应用于塑料、橡胶、石棉代用品、油漆、涂料等领域,可增加制品硬度、抗弯强度、抗冲击性,改善材料的电学特性,提高热稳定性和尺寸的稳定性;后者属于低档产品,主要用于陶瓷和冶金工业[4–5]。因此,获得高长径比硅灰石是该领域的研究热点。
目前,合成硅灰石的方法主要包括高温烧结法、溶液反应–焙烧法两类。高温烧结法是以硅石和方解
收稿日期:2017–07–16。修订日期:2017–08–24。
基金项目:中国地质调查项目(12120113087700),中央高校基本科研业务费(53200859555)资助项目。
第一作者:罗征(1988—),男,博士研究生。
通信作者:马鸿文(1952—),男,博士,博士研究生导师,教授。Received date: 2017–07–16. Revised date: 2017–08–24.
First author: LUO Zheng (1988–), male, Doctoral candidate.
E-mail: luo.zheng1988@https://www.doczj.com/doc/4c7821391.html,
Correspondent author:MA Hongwen (1952–), male, Ph.D., Professor. E-mail: mahw@https://www.doczj.com/doc/4c7821391.html,