次磷酸钠废渣制备亚磷酸钠的工艺研究

Preparation of Sodium Phosphite from Waste Residue of Sodium Hypophosphite

以次磷酸钠废渣为原料,与氢氧化钠溶液反应制备亚磷酸钠,并对其工艺进行优化。确定最佳制备工艺条件为:反应温度100℃、反应时间4.0 h、渣碱质量比10∶3.6、渣水质量比1∶5;最佳精制工艺条件为:趁热过滤,用亚磷酸调节pH值7~8,直接蒸发浓缩、结晶。在此条件下,废渣中磷转化率高于90%,亚磷酸钠纯度大于98%。该工艺使次磷酸钠废渣中大量的磷得到充分合理利用,其副产物氢氧化钙可以作为生产次磷酸钠的原料返回至次磷酸钠生产车间,既降低了企业生产成本,又实现了废弃物的资源化利用。

Using waste residue of sodium hypophosphite as a raw material,we prepared sodium phosphite through the reaction of the waste residue of sodium hypophosphite and sodium hydroxide solution,and optimized the process.The optimum preparation conditions are determined as follows:the reaction temperature of 100℃,the reaction time of 4.0 h,the residue-alkali mass ratio of 10∶3.6,and the residue-water mass ratio of 1∶5.The optimum refining conditions are determined as follows:filtering at an elevated temperature,adjusting pH value of 7~8 with phosphorous acid,and direct evaporation,concentration,and crystallization.Under above conditions,the conversion rate of phosphorus in the waste residue and the purity of sodium phosphite are more than 90%and 98%,respectively.In this process,a large amount of phosphorus in the waste residue of sodium hypophosphate can be used fully and reasonably,and the by-product calcium hydroxide can return to the production workshop of sodium hypophosphite as a raw material,which not only reduces the production cost of the enterprise,but also realizes the resource utilization of waste.