Abrasive material regeneration method regenerates a cerium oxide abrasive material from a used abrasive material slurry containing the cerium oxide abrasive material and resulting from grinding a grinding subject having silicon as the primary component, characterized by regenerating the abrasive material containing cerium oxide through: a slurry recovery step (A) for recovering an abrasive material slurry discharged from a grinder; an isolation/concentration step (B) for adding a magnesium salt as an inorganic salt to the recovered abrasive material slurry, aggregating the abrasive material under the condition that the pH value of the mother liquor converted to 25 DEG C is at least 6.5 and less than 10.0, and thus isolating and concentrating the abrasive material from the mother liquor; and an abrasive material recovery step (C) for recovering the isolated and concentrated abrasive material.

Abrasive material regeneration method and regenerated abrasive material

A method is presented for recovery, in reusable form, of rare earth minerals and zirconia from waste materials containing them. The method includes: mixing an ammonium sulfate powder and a powder containing the oxide waste material; heating the mixture to decompose the waste into a residue; dissolving the residue in water; separating rare earth constituents from the solution; and subsequently using the separated rare earth constituent (salt or solution) as a raw material. Moreover, the reactants used in the recovery may be recovered by appropriate precipitation and concentration operations.

Method for recycling of rare earth and zirconium oxide materials

A method for recovery of cerium oxide from the abrasive waste composed mainly of cerium oxide arising from the polishing of glass substrates, said method including the steps of (i) adding to the abrasive waste an aqueous solution of a basic substance; (ii) adding to the resulting solution a precipitant, thereby forming precipitates composed mainly of cerium oxide, and removing the supernatant liquid; (iii) adding to the resulting precipitates a solution of an acid substance, thereby making said precipitate slightly acid to neutral; (iv) washing the precipitates with an organic solvent; and (v) drying and crushing the precipitates. The method males it possible to recycle abrasive waste into a pure abrasive composed mainly of cerium oxide which can be reused to polish synthetic quartz glass substrates for state-of-the-art semiconductor technology relating to photomasks and reticles.

Method for recovery of cerium oxide

PURPOSE: A rare earth metal oxide based regeneration inorganic abrasive for LCD and PDP glass panels and an inorganic abrasive waste sludge regenerating method for manufacturing the same are provided to safely remove inorganic impurities included in abrasive waste sludge and reuse the separated abrasive. CONSTITUTION: A mixture of organic abrasive waste sludge and distilled water is prepared(S100). Insoluble impurities are removed from the mixture using a mesh(S105). Acids are added to the mixture, and solid and liquid components are separated from the mixture through centrifugation(S110~S120). The solid components are repetitively washed with distilled water or deionized water(S125~S135). The distilled water or deionized water is removed and the solid material is heat-treated at a temperature of 100~120°C and dried(S145). The dried solid material is crushed(S150). The crushed solid material is calcinated at a temperature of 450~550°C for 100~150 minutes in an electric furnace of oxygen(O2) atmosphere(S155). Organic compounds included in the solid material are removed and the calcinated solid material is powdered(S160).

Recycling mineral abrasive for lcd and pdp glass panel based on rare earth metal oxides and method for recycling mineral abrasive using sludge disposal

The purpose of the present invention is to provide an abrasive regeneration method which, from a used abrasive, can recover an abrasive by an efficient method and can thereafter obtain a high-purity regenerated abrasive by a simple method. This abrasive regeneration method regenerates an abrasive from a used abrasive slurry and is characterized by said abrasive comprising at least one type of abrasive selected from diamond, boron nitride, silicon carbide, alumina, alumina zirconia, zirconium oxide and cerium oxide, and by abrasive regeneration involving a slurry recovery step (A) for recovering an abrasive slurry discharged from a polishing machine, a separation and concentration step (B) for adding an alkaline earth metal salt as an inorganic salt to the recovered abrasive slurry to aggregate the abrasive, and separating and concentrating the abrasive from a mother liquor, an abrasive recovery step (C) for recovering the separated and concentrated abrasive, and a second concentration step (D) for filter-treating the concentrated abrasive.

Abrasive regeneration method

PROBLEM TO BE SOLVED: To provide a method for regenerating cerium-based abrasive usually abandoned due to a substantial fall in a grinding speed. SOLUTION: The used cerium-based abrasive is made into slurry re-dispersed with water. The re-dispersed slurry is treated with acid. The obtained acid-treated slurry is subjected to solid-liquid separation. The obtained cake is dried and cracked, or preferably, the dried cake is baked and cracked. By performing these steps, the cerium-based abrasive is regenerated. As an acid, one or combination of two or more of hydrochloric acid, sulfuric acid, nitric acid, and hydrofluoric acid can be used. COPYRIGHT: (C)2008,JPO&INPIT

Method for regenerating cerium-based abrasive

PROBLEM TO BE SOLVED: To provide a process for efficiently recovering high-quality rare earth oxide from waste grinding slurry. SOLUTION: In a method of recovering rare earth elements, rare earth oxides are recovered from the waste grinding slurry containing rare earth elements in a first process [I] including steps (1)-(5), and ammonium sulfate of the process [I] and water are reproduced in a second process [II] of a step (6) and recycled in the process [I]. The process [I] comprises steps of: (1) mixing slurry containing rare earth oxides with a sulfuric acid compound, heating/roasting the mixture, and dissolving it in water to make rare earth element solution; (2) adjusting a pH value of the rare earth element solution and dissociating insoluble components; (3) adding precipitant to the solution to separate out rare earth carbonate; (4) dissociating the rare earth carbonate from the slurry; and (5) baking the rare earth carbonate to recover it as rare earth oxides. If the pH regulator and the precipitant in the process [I] are aqueous ammonia and ammonium salt, the process [II] comprises the step of: (6) aqueous ammonium sulfate solution from which the rare earth carbonate is separated is condensed to recover the aqueous ammonium sulfate solution and the water. COPYRIGHT: (C)2009,JPO&INPIT

Method for recovering rare earth elements

PROBLEM TO BE SOLVED: To provide an inexpensive process of efficiently recovering rare earth oxides of high quality from waste grinding slurry containing rare earth elements. SOLUTION: In a method of recovering rare earth elements, rare earth oxides are recovered from waste grinding slurry containing rare earth elements in a first process (I) including steps (1)-(5), and ammonium bicarbonate (precipitant) is reproduced and recycled in a second process (II) including steps (6)-(7). The process (I) comprises steps of: (1) mixing slurry containing rare earth oxides with oxidizing and reducing agents and acid, and heating and solving the slurry; (2) dissociating non-soluble components after adjusting the pH value of rare earth element solution; (3) adding ammonium bicarbonate to the solution to form rare earth carbonate; (4) dissociating the rare earth carbonate from the slurry; and (5) of baking the rare earth carbonate to recover it as rare earth oxides. The process (II) comprises steps of: (6) adding strong alkaline agent to a dissociated solution of rare earth carbonate to generate, condense and recover ammonium; and (7) bringing ammonium into contact with generated carbon dioxide to form ammonium bicarbonate solution and to recycle the welding as a precipitant for forming rare earth carbonates. COPYRIGHT: (C)2009,JPO&INPIT

Yoshiichi Ito

Papers

Method for regenerating cerium-based abrasive

Method for recovering rare earth elements

Method of recovering rare earth element