摘要
为将Ca(H_(2)PO_(4))2制备KH_(2)PO_(4)过程中的石膏资源化利用,以H_(3)PO_(4)与CaCO_(3)反应制备Ca(H_(2)PO_(4))2溶液,并与K_(2)SO_(4)溶液反应,进行Ca(H_(2)PO_(4))_(2)-H_(3)PO_(4)-K_(2)SO_(4)体系中石膏晶型和形貌调控研究。结果表明:通过改变反应时间、反应温度、SO^(2-)/_(4)过量系数和CaO含量等参数可对Ca(H_(2)PO_(4))_(2)-H_(3)PO_(4)-K_(2)SO_(4)体系中石膏晶型和形貌进行调控,制得短柱状α-CaSO_(4)·0.5H_(2)O。体系在温度高于95℃和CaO含量为3.0%~5.0%(质量分数,下同)时形成α-CaSO_(4)·0.5H_(2)O,在CaO含量为5.5%主要形成CaSO_(4)·2H_(2)O;反应时间长于20 min和SO^(2-)/_(4)过量系数大于1.4将形成K_(2)SO_(4)(CaSO_(4))_(5)·H_(2)O,导致石膏晶体表面缺陷增加。本实验条件下,适宜反应条件为:反应时间10 min、反应温度95℃、SO^(2-)/_(4)过量系数1.2和CaO含量5.0%,此条件下可制得长度42~70μm、直径13~24μm的短柱状α-CaSO_(4)·0.5H_(2)O,其抗折和抗压强度分别可达5.61 MPa和33.74 MPa,滤液中钾收率和脱钙率分别可达94.23%和83.80%。
In order to make the resource utilization of gypsum in the process of preparing KH_(2)PO_(4) from Ca(H_(2)PO_(4))2,the Ca(H_(2)PO_(4))2 solution prepared by the reaction of H_(3)PO_(4) and CaCO_(3) was mixed with K_(2)SO_(4) solution.Then the regulation of gypsum crystalline and morphology in Ca(H_(2)PO_(4))_(2)-H_(3)PO_(4)-K_(2)SO_(4) system was studied.The results show that the short columnarα-CaSO_(4)·0.5 H_(2)O can be obtained from Ca(H_(2)PO_(4))_(2)-H_(3)PO_(4)-K_(2)SO_(4) system by changing the reaction condition,including reaction time,reaction temperature,SO^(2-)/_(4)excess coefficient(ξ)and CaO content.The α-CaSO_(4)·0.5 H_(2)O is formed at temperatures above 95℃and CaO content of 3.0%to 5.0%(mass fraction,the same below),while CaSO4·2 H2O is formed at low temperatures and CaO content of 5.5%.Meanwhile,with the increase of CaO content in the range of 3.0%to 5.0%,the aspect ratio ofα-CaSO_(4)·0.5 H_(2)O decreases.As the reaction time is longer than 20 min and the SO^(2-)/_(4)excess coefficient is greater than 1.4,K_(2)SO_(4)(CaSO_(4))_(5)·H_(2)O is easily formed,resulting in the increase of surface defects of gypsum crystals.Under the conditions of reaction time of 5 min,reaction temperature of 95℃,SO^(2-)/_(4)excess coefficient of 1.2 and CaO content of 5.0%,a short columnarα-CaSO_(4)·0.5 H_(2)O crystals with length of 42μm to 70μm and diameter of 13μm to 24μm are prepared,the flexural strength and compressive strength of which are 5.61 MPa and 33.74 MPa,respectively.The yield of potassium and decalcification rate of the filtrate are 94.23%and 83.80%,respectively.
作者
吴钦
杨林
易芸
耿平兰
曹建新
WU Qin;YANG Lin;YI Yun;GENG Pinglan;CAO Jianxin(School of Chemistry and Chemical Engineering,Guizhou University,Guiyang 550025,China;Key Laboratory of Guizhou Province for Green Chemical Industry and Clean Energy Technology,Guizhou University,Guiyang 550025,China;Engineering Research Center of Efficient Utilization for Industrial Waste,Guizhou University,Guiyang 550025,China;Guizhou Institute of Products Quality Inspection&Testing,Guiyang 550016,China)
出处
《人工晶体学报》
CAS
北大核心
2021年第6期1104-1111,1122,共9页
Journal of Synthetic Crystals
基金
国家重点研发计划(2018YFC1900202)
贵州省科技计划(黔科合服企[2018]4011)。
