煅烧-铵盐两步浸出法对磷矿浮选尾矿钙镁回收研究

Recovery of calcium and magnesium from phosphate rock flotation tailings by calcination-ammonium salt two-step leaching process

采用煅烧-铵盐两步浸出法对磷矿浮选尾矿中的钙和镁进行回收,考查了铵盐种类及用量、固液比、反应温度、反应时间等对氧化钙和氧化镁浸出率的影响。磷矿浮选尾矿的最佳煅烧温度为1000℃、煅烧时间为60 min。在氧化钙与氯化铵摩尔比为1∶2.2、固液比为1∶7、反应温度为35℃、反应时间为20 min的条件下,氧化钙的浸出率为56.69%,氧化镁的浸出率为4.29%,较好地实现了钙镁分离。在氧化镁与硫酸铵摩尔比为1∶1.4、固液比为1∶10、反应温度为90℃、反应时间为60 min的条件下,氧化镁的浸出率达83.43%。煅烧-铵盐两步浸出法能有效实现对磷矿浮选尾矿的二次利用。

Calcium and magnesium were recovered from phosphate flotation tailings by calcination-ammonium salt two-step leaching process.The influence of the variety and dosage of ammonium salts,solid-liquid ratio,reaction temperature and reaction time on the leaching rate of calcium oxide and magnesium oxide were investigated.It is concluded that the optimum temperature and time for calcination of the phospahte flotation tailings were 1,000℃and 60 minutes respectively.Satisfactory separation of calcium from magnesium can be achieved at quicklime to ammonium chloride mole ratio of 1∶2.2,solid-liquid ratio of 1∶7,at reaction temperature of 35℃with reaction time of 20 minutes,resulting in 56.69%CaO leaching rate and 4.29%MgO leaching rate.With magnesium oxide to ammonium sulfate mole ratio of 1∶1.4,solid-liquid ratio of 1∶10,reaction temperature of 90℃and reaction time of 60 minutes,83.43%MgO leaching rate was obtained.The secondary utilization of phosphate flotation tailings is likely to be realized efficiently by calcination-ammonium salt two-step leaching process.