摘要
为了合理利用低浓度氯化钙废液,以浓硫酸与氯化钙废液反应制备的二水硫酸钙为原料,再以CaCl2-HClH2O混合电解质溶液为相转变介质,制备应用价值高的半水硫酸钙。文中研究了该体系中温度和HCl,CaCl2,Mg2+质量分数对CaSO4·2H2O脱水转变为CaSO4·0.5H2O所需的相转变时间、晶体形态变化的影响。以结晶水质量分数确定相转变时间,以晶体图片表征晶体形态的变化。结果表明:相转变时间随着温度以及HCl,CaCl2,Mg2+质量分数的增加而逐渐缩短;单因素实验研究中,温度高于343.15K,HCl,CaCl2,Mg2+质量分数分别超过3.65%,38.85%,0.001%时,相转变时间缩短趋势减缓;晶体形态逐渐由片状转变为针状。该方法可作为HCl法湿法磷酸工艺中低浓度氯化钙废液利用的有效途径。
In order to deal with the CaCl2 solutions,with CaSO4·2H2O from the reaction of waste CaCl2 solutions and concentrated H2SO4 as raw materials, and CaCl2-HCl-H2O electrolyte solutions as phase transformation medium,the calcium sulfate hemihyhrate with more application value was prepared. The effects of temperature,composition of solutions,and the impurity Mg2 ＋on the phase transformation time（ PTT） and the change of crystal morphology were investigated. The PTT was determined by the change of the crystallization water content and the crystal morphology was characterized through the images of the crystals. The results indicate that PTT decreases with the increase of temperature and the mass fraction of HCl,CaCl2,Mg2 ＋; the PTT shortens quickly when the temperature is above 343. 15 K and the mass fractions of Ca Cl2,HCl,Mg2 ＋are over 38. 85%,3. 65%,0. 001%,respectively,and then flattens out with the increase of the studied effect factors; the plate-like crystals gradually transform into the needle crystals during the transformation process. This method can be an effective way to treat the low concentration of waste CaCl2 solutions produced by wet-process phosphoric acid based on hydrochloric acid method.
出处
《化学工程》
CAS
CSCD
北大核心
2015年第2期54-58,共5页
Chemical Engineering(China)
关键词
CACL2
HCL
硫酸钙
相转变
晶体形态
calcium chloride
hydrochloric acid
calcium sulfate
phase transformation
crystal morphology
