以氢氟酸协同草酸精制石英砂尾矿及其作用机理

高纯度石英砂在建筑、玻璃制造、铸造等工业领域应用广泛,将石英砂尾矿进行除Fe、Al处理,能够得到相当于高纯度石英砂的替代产品。本研究采用广东河源石英尾矿为原料,提出以氢氟酸协同草酸精制石英砂尾矿的方法,并确定最佳的条件。通过对草酸Fe³⁺溶解络合实验,确定了草酸用量与反应温度;通过HF协同草酸精制实验,确定了酸浸反应时间与物料比例。结果表明,80℃时200g粒径60目的石英砂尾矿在100mL饱和草酸溶液与HF比为25:1(体积比)的酸浸液中,浸泡4h时对石英尾矿的处理可以达到精制的目的。精制后石英砂中二氧化硅含量可以达到99.97%,白度达87.5.实验表明,通过补加草酸与HF可实现精制液的循环应用。冷却失效的精制液可回收结晶析出的草酸,剩余精制液与石英砂水洗液一起进行尾液处理。尾液处理采用饱和澄清石灰水将废液中的杂质沉淀析出,尾液与饱和澄清石灰水的体积比为1:13时处理效果最好,处理后可以达到中水的排放标准。

Refining quartz sand tailings and mechanisms by hydrofluoric acid associated with oxalic acid

High purity quartz sand is widely used in construction,glass manufacturing,casting and other industrial fields. In order to obtain the replacement products of high purity quartz sand,quartz sand tailings were treated by removing Fe and Al. In this work,the method of quartz tailings from Guangdong Heyuan as raw material refined with hydrofluoric acid associated with oxalate was proposed,and the optimum operating conditions were also provided. Oxalic acid dosage and reaction temperature were determined by oxalic acid complexation experiments. The acid leaching reaction time and material ratio were determined by refining experiments via hydrofluoric acid associated with oxalic acid. The results showed that the best operating conditions of refining the quartz sand tailings were as follows. Quartz sand tailings of 200g with the particle size≤250mm were immersed into the 100mL mixed solution of saturated oxalic acid and hydrofluoric acid in the volume ratio is 25:1 for 4 hours. Temperature was kept at 80℃。 After refining,the silica content in the refined quartz sand tailings could reach 99.97%,with the whiteness of 87.5. Experimental results demonstrated that refined solution was recycled by adding oxalic acid and hydrofluoric acid. Oxalic acid could be crystallized from the uncooled refined solution. The residual refined solution and refined quartz sand water lotion was treated as waste liquid. The impurities in the waste liquid were precipitated by the addition of a saturated lime water. The experimental results showed that the tail liquid was treated completely when the volume ratio of the tail liquid and the lime water is 1:13 and after the end solution treatment,the tail liquid can be used as recycled water discharge.