The invention relates to a process for producing a glass substrate for a cover glass for use in electronic appliances. The process is characterized by including: an etching step in which a glass substrate is etched with an acidic etching solution; and a removal step in which an alkali fluoroaluminate which is a compound adhered to an acid-resistant substance and which resulted from the etching step and became acidic through the etching step is removed with an acidic electrolyte solution that contains metal ions. A device for producing a glass substrate for a cover glass for use in electronic appliances is provided, the device being characterized by including: an etching solution feeder for etching a glass substrate with an acidic etching solution; and a means for removing an alkali fluoroaluminate which is a compound adhered to an acid-resistant substance and which generated by contact with the etching solution and became acidic because of the etching solution, with an acidic electrolyte solution that contains metal ions.

Process and device for producing glass substrate for cover glass for use in electronic appliance, and method and device for removing alkali fluoroaluminate

PROBLEM TO BE SOLVED: To produce sodium silicofluoride by using, as a raw material, hydrosilicofluoric acid contained in a fluorine-based waste liquid or generated in a treating process of the fluorine-based waste liquidSOLUTION: Sodium silicofluoride is produced by reacting hydrosilicofluoric acid contained in a fluorine-based waste liquid with a sodium compound or by reacting hydrosilicofluoric acid formed by the reaction of hydrogen fluoride contained in the fluorine-based waste liquid with a silicon oxide compound, with the sodium compound It is possible to produce sodium silicofluoride having a quality at an industrial chemical level

Method for producing valuable substance from waste liquid

The present invention obtains an inexpensive material with a photocatalytic function. A photocatalyst is obtained by halogenation of a glass fiber with silicon dioxide in the composition thereof. Molten quartz, soda-lime glass, alkali-free glass, or borosilicate glass can be used for the glass. Hydrofluoric acid, hydrochloric acid, and hydrobromic acid can be used in the hydrohalogen acid, but hydrofluoric acid is most desirable. The form may be granular, fibrous, or sheet form. The glass exhibits a photocatalytic function even with non-ultraviolet, visible light and has a water-repelling effect. This glass is capable of decomposing organic matter and the plate form is used as window glass for buildings and as window glass for vehicles and other transportation devices. The fibrous form is used as a filter for air suction and discharge devices.

Glass with photocatalytic function

PROBLEM TO BE SOLVED: To provide a method for producing high purity sodium silicofluoride and potassium borofluoride as valuable materials and hydrochloric acid by using as raw material a fluorine-containing waste liquid discharged after use of a hydrofluoric acid-based chemical etching agent for a glass substrate to which hydrochloric acid has been added. SOLUTION: The fluorine-containing waste liquid, discharged after use of a hydrofluoric acid-based chemical etching agent for glass to which hydrochloric acid has been added, is treated as a raw material in the order of the following (a) to (e): (a) aluminum in the waste liquid is reacted with an alkaline earth salt and then separated as an alkaline earth fluoroaluminate; (b) hydrofluoric acid contained in the aluminum-freed waste liquid is reacted with a silicon oxide compound to be converted into hydrosilicofluoric acid; (c) a sodium salt is added to the waste liquid containing hydrosilicofluoric acid to synthesize sodium silicofluoride; (d) synthesized sodium silicofluoride is separated and a potassium salt is added to the remaining liquid to synthesize potassium borofluoride; and (e) synthesized potassium borofluoride is separated and the remaining liquid is distilled to produce hydrochloric acid. Sodium silicofluoride, potassium borofluoride and hydrochloric acid as valuable industrial chemicals can be produced. COPYRIGHT: (C)2011,JPO&INPIT

Method for producing valuable material and hydrochloric acid from waste liquid

PROBLEM TO BE SOLVED: To provide a method for producing alkali metal silicofluoride and nitric acid with high purity as valuables with a waste liquid of mixed acid of hydrofluoric acid and nitric acid as raw material. SOLUTION: The production method uses a waste liquid of mixed acid of used hydrofluoric acid and used nitric acid as raw material, and performs treatment in order of the following (a) to (c): (a) hydrofluoric acid included in a waste liquid is reacted with a surplus silicon oxide compound to be converted into hydrosilicofluoric acid; (b) a surplus alkali metal salt is added to the waste liquid after the conversion into the hydrosilicofluoric acid to produce an alkali metal silicofluoride; and (c) after the production of the alkali metal silicofluoride by the (b), the separated liquid and an aluminum compound or a boron compound are reacted with each other, and fluorine as the constituent element of the hydrosilicofluoric acid contained in the liquid is converted into nonvolatile fluoroaluminic acid or borofluoric acid having a high boiling point, and then, nitric acid is produced by a distillation process. According to the method, high purity alkali metal silicofluoride and nitric acid can be produced. COPYRIGHT: (C)2011,JPO&INPIT

Method for producing alkali metal silicofluoride and nitric acid from waste liquid

PROBLEM TO BE SOLVED: To provide a method and an apparatus for separating/recovering recyclable hydrofluoric acid and silicofluoric acid efficiently from a waste liquid containing hydrofluoric acid and silicofluoric acid. SOLUTION: The method comprises separating the solid in the waste liquid containing hydrofluoric acid and silicofluoric acid and then first concentrating the waste liquid by distillation, and recovering an aqueous solution containing mainly hydrofluoric acid and an aqueous solution containing mainly silicofluoric acid, respectively. Other materials are remained in the distillation pot residue. The aqueous solution containing hydrogen fluoride can be recycled as a chemical etching treatment liquid for glass after adjusting the concentration by adding hydrofluoric acid. The aqueous solution containing silicofluoric acid can be recycled as synthetic raw materials of silicofluoric acid and silicofluoride for sales on the market by converting the hydrofluoric acid to silicofluoric acid by adding silicon dioxide and further by adjusting the concentration to a given one by diluting it with water. COPYRIGHT: (C)2008,JPO&INPIT

Kei Gen

Papers

Method and apparatus for separating and recovering acid components from waste liquid containing hydrofluoric acid and silicohydrofluoric acid