两种白钨矿碱分解溶液的蒸发与结晶过程研究
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摘要
本文采用旋转薄膜、玻璃真空蒸发器,对两种组成不同的白钨矿的苛性钠浸出溶液,选择了两种蒸发温度(90℃和80℃)下的蒸发-结晶试验。蒸发-结晶过程是按照流程设计的要求,所进行的承上启下的中间过程。目的是取得含有与不含有钼酸钠的钨酸钠结晶,以方便萃取分离钨/钼过程使用,并节省调整酸度过程的耗酸量;同时,取得高浓度氢氧化钠溶液,以便循环使用苛性钠试剂,并节省浸出试剂的消耗量。试验结果表明,对于含钼的钨酸钠-苛性碱浸出溶液而言,蒸发-结晶温度为90℃时(-0.098 MPa,56 r/min),尽管,氢氧化钠的回收率达到了尽善尽美,ηNa OH=100%,但是,美中不足的结晶率分别是:ηW=84.39%和ηM o=69.60%。即钨酸钠和钼酸钠的循环率分别为:ρw=16.17%和ρMo=31.29%。对于不含钼的钨酸钠-苛性碱溶液而言,蒸发-结晶温度为80℃,(-0.098 MPa,56 r/min),尽管,氢氧化钠的回收率接近完美,ηNa OH=100.0%,但是,美中不足是钨酸钠的循环率达到了,ηW=17.00%。两种结果表明,蒸发-结晶温度范围为80~90℃下,氢氧化钠的回收率,尽如人意,美中不足的是钨酸钠的循环率达到了16.1%~17.0%,钼酸钠的循环率达到31.29%。钨酸钠和钼酸钠之间的分离系数范围是1.21~1.56。
Evaporation and crystallization of two kinds of leaching solution of scheelite were tested by glass evaporator of film rotary so as to recover caustic soda in the leaching process and to get the sodium tungstate in the liquidliquid extraction process. The results have shown that there are two kinds of status. One is the solution bearing molybdenum and another is the solution free molybdenum. Although the former( 90℃,- 0. 098 MPa,56 r / min) is to get complete recovery of caustic soda( ηNa OH= 100%),bring a few and a larger recycle rate of 16. 17% and31. 29%. The latter( 80 ℃,- 0. 098 MPa,56 r / min) is to get recovery rate of sodium hydroxide( ηNa OH=100. 0%),bring a certain recycle rate of the sodium tungstate,17. 00%. In the both of evaporation-crystallization process,the recycle rate of sodium tungstate is about 16. 17% ~ 17. 00% and the recycle rate of sodium molybdate is 31. 29%. The separation coefficient between tungsten and molybdenum is about 1. 21 ~ 1. 56.
Evaporation and crystallization of two kinds of leaching solution of scheelite were tested by glass evaporator of film rotary so as to recover caustic soda in the leaching process and to get the sodium tungstate in the liquidliquid extraction process. The results have shown that there are two kinds of status. One is the solution bearing molybdenum and another is the solution free molybdenum. Although the former( 90℃,- 0. 098 MPa,56 r / min) is to get complete recovery of caustic soda( ηNa OH= 100%),bring a few and a larger recycle rate of 16. 17% and31. 29%. The latter( 80 ℃,- 0. 098 MPa,56 r / min) is to get recovery rate of sodium hydroxide( ηNa OH=100. 0%),bring a certain recycle rate of the sodium tungstate,17. 00%. In the both of evaporation-crystallization process,the recycle rate of sodium tungstate is about 16. 17% ~ 17. 00% and the recycle rate of sodium molybdate is 31. 29%. The separation coefficient between tungsten and molybdenum is about 1. 21 ~ 1. 56.
引文
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[3]梅支舵.钼酸钠的结晶率、纯度和p H的关系[J].矿产保护与利用,2000,(1):39-41.
[4]徐志昌,张萍.双极膜回收钨酸钠中游离碱的研究[J].中国钼业,2013,37(2):42-48.
[5]顾珩,汪剑岭,王继民,等.高钼钨酸钠溶液萃取分离钨钼的研究[J].稀有金属与硬质合金,1997,(129):7-10.
[6]李庆生,贺小华,尹侠.薄膜蒸发器配套72%片碱生产装置[J].氯碱工业,2003,(8):4-5.
[7]李庆生,贺小华,尹侠.一种用于生产72%片碱的新装置[J].氯碱工业,2004,(7):4-6.
[8]徐志昌,张萍.超高浓度溶液化学与Σ捏合机械力学化学反应器[J].中国钼业,2015,29(5):4-9.