利用磷石膏、钾长石制备硫酸钾的基础研究

【作者】 王雪；

【导师】 张召述；

【作者基本信息】 昆明理工大学 ， 应用化学， 2009， 硕士

【摘要】 磷石膏是湿法磷酸生产过程产生的主要固体废弃物,目前我国利用率不足10%,其所引发的环境污染、土地占用和资源浪费问题已成为制约磷肥企业可持续发展的关键。与此同时,我国可溶性钾资源严重不足而不溶性钾资源如钾长石矿储量却十分丰富。将钾长石与磷石膏有机地结合起来生产硫酸钾,实现钾长石与磷石膏的合理利用,具有重大的经济价值和学术意义。本文以磷石膏、钾长石和焦炭为原料,以理论失重率、硫酸钙分解率和钾熔出率为指标,在管式反应器中进行高温煅烧,考察了反应气氛、物料配比、原料粒度、助熔剂种类及用量等因素对体系实验指标的影响,并得到了最优化配方。经实验研究得出如下结论：(1)磷石膏—焦炭、分析纯石膏—焦炭配料体系分别在还原性气氛、氧化性气氛、复合气氛下的煅烧失重率和CaSO4分解率呈现随反应温度升高而增大趋势；但是分解产物明显不同,还原气氛的分解产物主要是硫化钙,氧化气氛和复合气氛下的分解产物主要是氧化钙。(2)磷石膏—焦炭—钾长石、分析纯石膏—焦炭—钾长石配料体系在还原气氛、氧化气氛、复合气氛下的煅烧失重率和CaSO4分解率也随反应温度升高呈现明显增大趋势；在相同温度下,在还原性气氛下钾熔出率最低,氧化气氛和复合气氛下钾熔出率较高。(3)为了获得较高的钾熔出率,采用单因素实验法得出以下结论：钙硅比为1.2,焦炭用量超出实验给定区间上限,仍需增加,焦炭粒度在160目≤d≤140目区间,助熔剂为焦炭质量25%的Na2CO3。(4)利用正交实验法分析了钾长石、磷石膏、焦炭和助剂四个因素对反应的影响,获得了钾熔出率较高的工艺条件。优化方案为：焙烧温度为1000℃、焙烧时间为1.0h、在弱氧化性气氛中反应、助熔剂用量为钾长石总量的30%,钾熔出率可达90.0%。(5)采用XRD和红外探讨了反应机理,验证了煅烧产物中硫酸钾的存在。(6)针对提取硫酸钾后得到的固体废渣,进行了碳分提铝,并将二次废渣用于制备CBC复合材料,取得了初步结果。更多还原

【Abstract】 Phosphogypsum is that main solid waste in wet process of phosphoric acid production. The utilization ratio of phosphogypsum in our country does not reach 10% at present. The problems of environmental pollution, land occupancy and resources waste initiated by phosphogypsum have already become the key of restricting sustainable development of phosphate fertilizer enterprise. Meanwhile, solubility potassium resource in our country is grave insufficient but the reserve of insoluble potassium resource such as potassium feldspar ore is very rich. The way that organically combine potassium feldspar and phosphorus gupse to produce potasium sulphate, and to make reasonableness use of potassium feldspar and phosphogypsum, has significant economic value and academic significance.In this paper, the influence of reaction atmosphere, materials ratio, particle size of raw materials and the type and amount of help flux to experimental indicators has been studied, through high temperature calcination in tubular reactor, taking phosphogypsum, potassium feldspar and coke as raw materials, and taking the theoretical weight loss rate, decomposition rate of calcium sulfate and potassium melt rate as indexes. The optimized formula has been founded.The study results show that:(1) Under the deoxidation atmosphere, oxide nature atmosphere and compound atmosphere, the calcination weightlessness rate and CaS04 decomposer rate of both phosphogypsum-coke and analytical pure gupse-coke system, have presentated an enhances trend with the reaction temperature raises; but break up outcomes are in great difference, the decomposition outcome under deoxidation atmosphere is mainly calcium sulfide, the decomposition outcome under oxide atmosphere and the compound atmosphere are mainly calcium oxide.(2) Under the deoxidation atmosphere, oxide nature atmosphere and compound atmosphere, the calcination weightlessness rate and CaS04 decomposer rate of both the phosphogypsum-coke-potassium feldspar and analyses pure gupse-coke-potassium feldspar system, have presentated an enhances trend with the reaction temperature raise; under the identical temperature, potassium melts out rates is minima under deoxidation nature atmosphere, potassium melts out rate is comparatively highly under the oxide atmosphere and the compound atmosphere.(3)For gaining higher potassium rate, adopt single factor experiment way to find the following conclusions:calcium silicon proportion is 1.2,coke dosages has exceeded upper limit of given experiment, still need to be increasd;coke granularity is in 160 mesh≤d≤140 mesh, helping flux is Na2CO3,25% of coke quality.(4) Though orthogonality experiment way to analyze the impact of potassium feldspar, phosphogypsum, coke and assistant over reaction. Have gained higher potassium melting out rate technological conditions. Optimize scheme is:the baking temperature is 1000℃, baking time is 1.0h, reacted in weak oxide nature atmosphere, helping flux dosages is 30% of potassium feldspar quantity, potassium melting out rate amounts to 90.0%.(5) Though XRD and infrared investigation way discussed reaction mechanism and verified that there existed potasium sulphate in calcination outcome.(6) Aiming at the waste residue that potasium sulphate have been extracted, carried the carbon separating progress to extracte aluminium, repeated waste residue has been used to prepare CBC compound material and has got first step result.更多还原