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Recovery of hydrofluoric acid

A recovery method and fluoric acid technology, applied in the fields of fluorine/hydrogen fluoride, heating water/sewage treatment, etc., can solve the problems of inoperable equipment and difficult on-site implementation, and achieve the purpose of preventing the decrease of heat transfer efficiency, simplifying equipment and preventing scale. Effect

Inactive Publication Date: 2012-03-28
MITSUBISHI CHEM ENG CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But in above-mentioned hydrofluoric acid waste liquid, dissolve the metals such as Si, B, Al, Ca, Zr to exist, recover by distillation, the metal component in the concentrate (separated and concentrated hydrofluoric acid waste liquid) will Separation, thus creating scale in the system including the distillation column, rendering the equipment inoperable
In addition, as in the usual production of hydrofluoric acid, once hydrogen fluoride is produced by the distillation method, the scale of the equipment becomes large, so it is difficult to implement it on-site from an economical point of view.

Method used

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  • Recovery of hydrofluoric acid
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  • Recovery of hydrofluoric acid

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Embodiment

[0051] According to the recovery method of the present invention, purified hydrofluoric acid is recovered from the hydrofluoric acid waste liquid discharged from the etching process of the glass substrate. As the hydrofluoric acid waste liquid to be treated, a waste liquid having a concentration of 10% by weight and a concentration of metal components such as Si, B, Al, Ca, and Zt of 1% by weight was prepared. In the crude hydrofluoric acid evaporation process, the hydrofluoric acid waste liquid is supplied to the evaporation kettle (1) at a flow rate of 300cc / hour, and the hydrofluoric acid waste liquid is heated at 74° C. under a pressure condition of 100 Torr, and the crude hydrofluoric acid is recovered as steam, It is fed to the first distillation column (21). At this time, 98% sulfuric acid was added to the evaporator (1) at a flow rate of 3 cc / hour. In addition, by producing crude hydrofluoric acid, the hydrofluoric acid waste liquid was concentrated to a concentration...

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Abstract

A process for recovering fluoric acid from the waste liquid generated during etching glass plate without generating scale includes such steps as adding sulfuric to said waste liquid, supplying the mixture to evaporator, heating, recovering the vapor to obtain coarse fluoric acid while separating and concentrating waste liquid, distilling said coarse fluoric acid in the first distilling tower to separate concentrated fluoric acid and recover water, distilling the concentrated fluoric acid in the second distilling tower to obtain refined fluoric acid and waste liquid.

Description

technical field [0001] The present invention relates to a method for recovering hydrofluoric acid, in particular, to a method for recovering hydrofluoric acid from hydrofluoric acid waste liquid containing silicon dioxide components and metal components discharged from the etching process of glass substrates, etc. by distillation. Background technique [0002] In the etching of glass and glass substrate, use for example concentration is the hydrofluoric acid (hereinafter referred to as " hydrofluoric acid ") of about 15 weight %, such hydrofluoric acid, usually on-site (on-site) by diluting about with pure water Prepared with 50% by weight of high-concentration hydrofluoric acid. Then, in the process of utilizing hydrofluoric acid such as above-mentioned etching, the hydrofluoric acid waste liquid containing silicon dioxide component and metal component is discharged, but such waste liquid contains a large amount of unutilized hydrofluoric acid in the reaction, so it is desi...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B7/19C02F1/04
Inventor 宫田坚洋亀山薰川瀬泰人
Owner MITSUBISHI CHEM ENG CORP