To provide a method and equipment for conversion of a polishing waste liquid into a glass raw material which recycle a large amount of the polishing waste liquid of other kind of glass by converting it into the glass raw material.

A polishing material and glass fine powder after polishing a glass for cathode-ray tube and the like by using a slurry in which the polishing material is suspended are mixed in the polishing waste liquid 13. The polishing waste liquid 13 is supplied to an agglomeration tank 14, in which an agglomeration agent 15 is added to generate agglomerated matter 16. The agglomerated matter 16 is supplied to a sedimentation tank 17 to generate sediment 18. The sediment 18 is supplied to a concentration tank 19 to generate precipitate 20. The precipitate 20 is supplied to a dehydrator 22 to generate a polishing sludge 23. The polishing sludge 23 is granulated and dried to produce the glass raw material 26. The polishing waste liquid 27 of the other glass types is supplied to the equipment for conversion of the polishing waste liquid 13 into the glass raw material.