钾长石水热法制备矿物钾肥工艺研究

发布时间：2018-03-30 11:15

  本文选题：钾长石矿　切入点：钾肥　出处：《成都理工大学》2017年硕士论文

【摘要】：我国作为全球最大的钾盐和钾肥需求国之一,钾肥消费量一直大于生产量,钾肥对外依附度达50%左右。合理开发利用国内储量丰富的难溶性含钾盐矿制造钾肥,积极开展提钾工艺研究,可在一定程度上弥补国内缺乏可溶性钾盐资源的不足,缓解我国钾肥供需矛盾。钾长石是一种自然界分布极广,我国储量极其丰富的难溶含钾硅酸盐矿物。本文以四川乐山峨边五渡低钾含量钾长石为研究对象,采用水热反应制备多元素矿物质肥料。论文通过四川乐山峨边五渡低钾含量钾长石XRD、XRF分析,确定该矿石主要化学成分为SiO2、Al2O3、K_2O。物相组成为斜微长石、石英、钠长石。不同粒径矿石分析结果表明随着矿物粒度的减小,硅的含量SiO2的含量在67.90%到69.31%范围内逐渐减少,而K_2O的含量在9.57%到10.19%范围内略有增加,斜微长石的含量在56.61%到60.27%范围内有增加的趋势。矿石K_2O平均含量约为10%。以钾的溶出率和产物肥料中有效K_2O含量为评价标准,采用单因素法进行了反应工艺条件优化实验,结果表明以氧化钙为助剂,K的溶出率和产物中有效K_2O的含量随温度、压力、液固比、时间的增大而呈增加的趋势。K的溶出率随CaO用量的增加而增大,产物中有效K_2O含量随CaO用量增加而呈先增加后减小的趋势。温度、CaO的用量对K的溶出率和产物中有效K_2O的含量影响均较为显著。确定工艺条件:以氧化钙为助剂,Ca/(Si+Al)摩尔比为1.00,液固比仅为1.8∶1,反应温度为250℃,压力为8Mpa,反应时间20h。水热反应后的产物中钾的溶出率可到达85%,产物中K_2O的含量可达4.76%。产物肥料经XRD、XRF、SEM分析可知其主要组成是托贝莫来石(分子式为Ca5Si6O18·5H2O)和水钙铝榴石(分子式为Ca3Al2(Si O4)(OH)8)和斜方硅钙石(分子式为Ca4Si3O10·2H2O),钾多以KOH的形式存在。用0.5mol/L盐酸溶液和蒸馏水作为浸取剂,对产物中的肥料组分进行浸取,由ICP-OES分析结果可知,产物有效肥料组分分别为:4%可溶性钾(以K_2O计量,包括水溶性和枸溶性)、25%枸溶性硅(以SiO2计量)、44%的枸溶性钙(以CaO计量)以及总含量0.4%的枸溶性铁和镁以及锌硼锰等微量元素;实验考察了产物中钾的时间释放效应,产物中的水溶性钾在水中的释放速率较慢,可能是矿物肥料中钙、等硅难溶性的组分包裹所致,枸溶性的钾在酸的作用下释放速率较快。对产物外观特征进行了测定,其疏松堆密度为0.65g/cm3左右,与SEM图示产物结构疏松,存在大量微米级孔径的结论相符合。产物pH值为11左右,为碱性肥料,适用于酸性土壤,含水量低于0.5%。探讨优化工艺条件下,钾长石矿的分解机理以及水热反应中各元素存在形式及组成变化。通过对不同时间段的固体反应物XRD分析可知,反应助剂中的Ca2+交换了钾长石中的K+,OH-破坏了钾长石的晶体结构,由原来的斜微长石转变为过渡态C-S-H凝胶,C-S-H再转变为最终的托贝莫来石和斜方硅石,Al2O3与部分SiO2以及CaO在水热条件下形成了水钙铝榴石。通过土培实验得出,产物肥料对作物肥效明显,有利于提高产量,并且中和了酸性土壤,有利于根系的生长。初步验证了产物的肥效。
[Abstract]:China is one of the world's largest salt and potash demand, fertilizer consumption has been greater than the amount of fertilizer production, degree of external dependence is about 50%. The rational development and utilization of abundant domestic potassium salt producing insoluble potash, and actively carry out the research process of potassium, can make up for the lack of domestic shortage of soluble potash resources in some degree, ease the contradiction between supply and demand of China's potash. Potassium feldspar is a very widespread in nature, insoluble potassium silicate minerals rich in reserves in China. This paper takes Sichuan Leshan Ebian five Du low potassium feldspar as research object, by hydrothermal reaction to prepare mineral fertilizers. The Sichuan Leshan Ebian five crossing the low potassium content of potassium feldspar XRD, XRF Al2O3 analysis, determine the main chemical compositions of the ores are SiO2, K_2O., phase composition as microcline, quartz, albite ore. Different particle size analysis results That with the decrease of mineral granularity, SiO2 content of silicon to 69.31% range decreased in 67.90%, and the content of K_2O in the range of 10.19% to 9.57% with a slight increase in microcline in the 56.61% to 60.27% range is increased. The average content of ore is approximately 10% K_2O. With the dissolution of potassium the effective rate and K_2O content in fertilizer products as the evaluation criteria, the reaction conditions are optimized by single factor method. The results show that with calcium oxide as additives, the dissolution rate and the effective content of K_2O in the product with temperature, pressure K, liquid-solid ratio, time increases and increased the release of.K the rate increased with the increase of the content of CaO, K_2O content in the product was first increased and then decreased with increasing CaO content. The temperature, the amount of CaO on the K of the dissolution of the effective content of K_2O rate and the product were more significant. Determine the process conditions were: 姘у寲閽欎负鍔╁墏,Ca/(Si+Al)鎽╁皵姣斾负1.00,娑插浐姣斾粎涓，

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