拜耳法氧化铝生产中草酸钠的苛化

Causticization of sodium oxalate during alumina production by Bayer process

本文对拜耳法氧化铝生产过程中,用石灰苛化法处理铝酸钠溶液中的草酸钠,以氢氧化钠的形式对其进行回收利用的工艺进行了研究。实验研究了温度、石灰用量以及Na OH浓度对苛化反应的影响,并探索了草酸钠与碳酸钠共同苛化的可行性。研究证明:反应温度的升高、石灰用量的增加对草酸钠转化成为氢氧化钠的过程具有促进作用,而氢氧化钠浓度的增加对苛化反应不利。用石灰苛化含草酸钠的工业铝酸钠溶液,氧化钙用量系数为1.30以上,温度高于85℃,反应时间为1.5小时草酸钠的苛化率能达到85%以上。

In this paper, the causticization of sodium oxaiate in sodium aluminate solution with lime and recycling in the form of sodium hydroxide in Bayer process are studied. Effects of reaction temperature, lime amount and concentration of sodium hydroxide are investigated. The feasibility of cansticizing Na2C2O4 together with Na2CO3 is considered. The results show that the increases of reaction temperature and the lime amount have a promoting effect on the conversion of sodium oxalate into sodium hydroxide, and the increase of concentration of NaOH gives harm to the reaction. For the cansticization of sodium oxalate in sodium aluminate solution the coefficient of lime dosage is above 1.30, and reaction temperature is higher than 85℃, the reaction time is about 1.5 hours, the conversion rate of sodium oxalate can be 85% and above.