Method for separating polishing material and regenerated polishing material

A method for separating a cerium oxide containing-abrasive from a used abrasive-containing slurry that contains the cerium oxide containing abrasive and a component derived from a polished object that has been polished in an abrasive device, the method comprising:

• collecting the used abrasive-containing slurry discharged from the abrasive device;
• adding a divalent alkali earth metal salt to the collected-used abrasive-containing slurry to form a mother liquid while a temperature of the collected-used abrasive-containing slurry is regulated in a range from 10 to 70° C.;
• aggregating the abrasive when the mother liquid has a property of measured or converted pH of lower than 10 at 25° C. so that sedimentation of the abrasive occurs, the aggregated abrasive settles, and a supernatant solution containing the component derived from the polished object is formed;
• and
• isolating the abrasive from the mother liquid;
• wherein the cerium oxide containing-abrasive is mainly comprised of cerium oxide rare earth material, optionally also containing one or more additional rare earth elements, and the polished object is a glass.