富硼渣制备硼酸及回收硫酸镁的新研究

New Research on Preparation of Boric Acid and Recovery of Magnesium Sulfate from Boron-rich Slag

富硼渣与焙烧后的硼镁矿相似,可代替硼镁矿作为硼和镁的来源。研究硼酸和硫酸对硫酸镁结晶的影响,结果表明,硼酸和硫酸对硫酸镁的结晶起促进作用。采用先高压回收一水硫酸镁再进行低温结晶的方法制备硼酸,综合利用硫酸浸出富硼渣的滤液,一水硫酸镁的浸出率可达73.66%,回收率能达到55.74%,纯度为96.07%;硼酸的浸出率可达98.85%,回收率能达到71.85%,纯度为99.55%,达到了工业硼酸的标准(GB538-90)。此方法不仅节省部分能源,而且最终滤液中的硼酸和硫酸镁可重复回收。整个工艺形成闭路循环,无废液排出。

Since the boron-rich slag is similar with roasted ascharite in the chemical composition,it could replace ascharite bringing boron and magnesium.The research finds that the boric acid and sulfuric acid can promote the crystallization of magnesium sulfate.When the way that the monohydrate magnesium sulfate is recovered by high pressure first and then the boric acid is prepared by low temperature crystallization method,the leaching rate of monohydrate magnesium sulfate can reach 73.66% with the recovery of 71.85% and the purity of 96.07% and the leaching rate of boron acid can reach 98.85% with the recovery of 71.85% and the purity of 99.55%,which is fit for the industrial standard（GB 538-90） for boric acid.The Filtrate of boron-rich slag leached by sulfuric acid got comprehensive utilization.This method not only can save energy,but also can recover the boric acid and magnesium sulfate in the final filtrate repeatedly.The whole process is a closed circle without discharging waste liquid.