Study On The New Process Of Rare Earth Polishing Powder For Recycling

In this paper, three new recovery processes called Semi Dry Process, Ammonium Roasting, Alkali Roasting have been developed, which using waste polishing powder as raw material and lab-scale test has been completed. And the feasibility of the three processes has been verified using the Intermediate test. The main contribution of this Semi Dry Process is improving the traditional wet-process to a high effective and environment friendly recycling method. Ammonia sulfate in this process was used as assistant reagent in calcinations. After that, a concentrated rare earth solution has been collected by water leaching. The impurity actions in this solution is less than that in the solution collected by concentrated sulphuric acid extraction, and can be separated directly. This new recovery process does not produce any acidic waste water and builds a cyclic utilization process, in which the assistant reagent can be recycled. Ammonium Roasting and Alkali Roasting primarily adopt changing the crystal shape and size of rare earth oxide and removing the impurities to recycle the waste rare earth polishing. The reaction conditions in the three recovery processes all have been tested by orthogonal experiment. Finally, a satisfied requirement has be found by improving the reaction conditions. The experiments have abandoned the complex traditional process, greatly reduce production costs, and the desired design data for the large-scale industrial production have been obtained.