Abstract: A polishing system performs chemical-mechanical polishing of an object to be polished using an abrasive slurry. The polishing system includes a polishing amount calculator that measures an amount of free metal ions of a metallic element derived from the object to be polished in a processed slurry and calculates a polishing amount of the object to be polished from the amount of the free metal ions. The object to be polished is a glass containing the metallic element of Group 1 or Group 2 of a periodic table.

Abstract: A recycled polishing agent slurry is prepared from a used polishing agent slurry after polishing a silicon material using a reference polishing agent slurry including a cerium oxide polishing agent and a dispersing agent. The preparation method includes: slurry collecting in which the used slurry discharged from a polishing machine is collected; separation and concentration in which the cerium oxide polishing agent in the collected slurry is separated from a component derived from the material to be polished and then concentrated, and polishing agent recycling in which a pH adjusting agent and the dispersing agent are added to the separated and concentrated cerium oxide polishing agent, and a recycled polishing agent slurry is adjusted to have a pH value at 25° C. of in a range of 6.0 to 10.5 and an electrical conductivity value in a range of 0.10 to 10.00 times that of the reference slurry.

Abstract: A polishing agent regenerating method in which a component of a polished material is removed from polishing agent slurry and a polishing agent is collected and regenerated is shown. The method includes at least, polishing, polishing agent slurry supplying, polishing agent slurry collecting, and sedimenting/separating/concentrating, performed in the above order. In the polishing agent slurry collecting or the sedimenting/separating/concentrating, a K2O density in the polishing agent slurry after dilution by water is performed is to be within a range of 0.002-0.2 mass %.