钾矿石用于磷炉造渣助熔联产钾肥机理研究

Both the reserves of phosphate resources and the capacity of phosphate chemical industry in Yunnan province take the first place in china. However, yellow phosphorus is the basic raw material of various fine phosphorus chemical industries， but its development is limited for high energy consumption in China, so the key to the sustainable development is to explore energy saving technology of yellow phosphorus. Because of lack of soluble potassium resources and high dependence degree of potash imports, using the rich resources of insoluble potassium to prepare soluble potash is the only way for the future development. Based on the principle of production of yellow phosphorus by electric furnace method and the analysis of thermodynamics, it is suggested that co-production of potash may be used by melting potassium ores in place of silica in the phosphorus furnace . Setting in one of two major advantage resources - phosphate rock and potassium ore in Yunnan, energy saving and consumption reducing can be realized by reducing the main reaction temperature at which the phosphorus furnace slag is melted. Making the use of instability and volatility of displacement reaction products - potassium oxide K2O, potassium can be concentrated in the electrostatic precipitation, then potash will be made by acid leaching. The preliminary screening of potassium ores was conducted by contrastive analysis of slag fusibility and liquidity in different systems. Then the types of potassium ores are determined according to the change of resistance with temperature in silica. On the basis of former research In the calcium oxide - potassium ore system, practical production is simulated by replacing silica with potassium ores. The mechanism of slag making with potassium ore fluxing and the transfer of potassium may be proved. This project is expected to provide theoretical basis and technical support for production of yellow phosphorus using potassium ore in electric furnace.

云南磷矿资源及磷化工产能全国第一。黄磷是多种精细磷化工的基本原料，亦是我国限制发展的高能耗产业，故开发节能降耗技术是黄磷可持续发展的关键；我国可溶性钾资源匮乏，钾肥进口依赖度高，因此，利用我国不溶性钾资源制备可溶性钾肥，是未来发展的必由之路。本项目在热力学分析的基础上，结合电炉法黄磷生产原理，提出用钾矿石替换硅石用于磷炉造渣助熔联产钾肥，集云南两大优势资源—磷矿石、钾矿石于一体，拟通过降低主反应、炉渣熔融温度实现磷炉节能降耗；利用置换反应产物—K2O不稳定、易挥发的特点，在电除尘灰中富集钾、酸浸生产钾肥。以热力学分析为基础，通过不同体系下炉渣熔融性、流动性研究对比分析，筛选钾矿石，再以硅石电阻随温度变化关系为依据，确定钾矿石种类；项目在氧化钙-钾矿石体系的基础上，进行钾矿石替换硅石实际生产模拟研究，探明钾矿石造渣助熔机理和钾迁移变化规律，预期可为钾矿石用于磷炉生产提供理论依据和技术支撑。

黄磷是制造磷化合物及其衍生物不可替代的原料。中国黄磷产能占世界的75%，目前黄磷生产均采用电炉法，是我国限制发展的高能耗、高污染行业，因此开发黄磷生产新工艺或节能降耗技术是黄磷可持续发展的关键。基于此，本课题组提出利用云南丰富的钾矿石替换传统硅石作生产助熔剂，通过形成熔点更低的残渣，以期达到降低生产操作温度，实现黄磷生产节能降耗，并利用K2O易升华的特点，从尾气中回收钾、生产钾肥的目的，从而有效缓解我国钾肥资源匮乏、进口依赖度高等问题。.课题在纯物质研究机理问题，实物配料体系模拟实际生产过程研究的总体构思下，通过项目的系统研究，培养研究生5名，取得了包括发表研究论文23篇在内的成果共计42项，并获得如下结论：.1..不论是硅石助熔或是钾矿石助熔，电炉法黄磷生产的反应历程未发生根本变化，首先是氟磷灰石脱氟，然后是磷酸钙与酸性物质（SiO2、Al2O3）形成高温稳定钙盐并释放出P2O5，最后P2O5被赤热的碳还原成单质磷，并以P4蒸汽形式逸出体系。.2..硅石助熔时，反应控制步骤为氟磷灰石脱氟，而钾矿石助熔时，反应控制步骤为磷酸钙的复盐反应。.3..相同酸度值下，钾长石体系反应活化能较硅石体系约低15%，表明钾矿石分解产物有类似催化剂功能；同等工艺条件下，钾矿石体系下磷的回收率较硅石体系提高2-5%，在满足生产实际回收率下，相同回收率，钾长石助熔时可降低操作温度100℃左右。.4..同等质量的残渣，钾矿石助熔与硅石助熔相比，钾矿石残渣特征温度较硅石残渣约低100℃；在1350℃下，钾矿石助熔残渣高温熔融物摊开面积是硅石残渣的1.5以上，充分说明其残渣熔融温度更低，亦即钾矿石助熔时，可获得熔融温度更低的低共熔物。.上述研究结果表明：钾矿石替换硅石用于电炉法黄磷生产作助熔剂及同步生产钾肥切实可行，并有利于降低生产能耗，研究达到了课题申报的预期目的。同时研究还发现，当用钾矿石替换硅石后，其自然冷却残渣属非晶相矿物，可直接用于生产微晶玻璃，因此，研究成果具有较好的推广应用价值。