Recovery of hydrofluoric acid

A recovery method, the technology of hydrofluoric acid, applied in the direction of fluorine/hydrogen fluoride, etc., can solve problems such as difficult on-site implementation and inoperable equipment, and achieve the effects of preventing scale, preventing the decline of heat transfer efficiency, and simplifying the device

Inactive Publication Date: 2007-09-05
MITSUBISHI CHEM ENG CORP +1
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Problems solved by technology

However, in the above-mentioned hydrofluoric acid waste liquid, there are dissolved metal components such as Si, B, Al, Ca, Zr, etc., which are recovered by distillation, and the metal components in the concentrated solution (separated and concentrated hydrofluoric acid waste liquid) will precipitate out and thus create scale in the system containing the retort 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
  • Recovery of hydrofluoric acid
  • Recovery of hydrofluoric acid

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Embodiment

[0051] Purified hydrofluoric acid was recovered from the hydrofluoric acid waste liquid discharged from the glass substrate etching process using the hydrofluoric acid recovery device shown in FIG. 1 . In the hydrofluoric acid recovery device, the effective volume of the evaporator (1) is 1000 cc, and the effective volume of the distillation tower (2) is 300 cc. 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.

[0052] In the heating operation in the evaporator (1), 800 cc of hydrofluoric acid waste liquid was heated at 74° C. under a pressure of 100 Torr, and the crude hydrofluoric acid was recovered as vapor and supplied to the distillation column (2). At this time, a total of 12 cc of 98% sulfuric acid was added to the evaporator (1) at a flow rate of 3 cc / hour. On the other hand, in the distillation operation of the...

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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, distilling said coarse fluoric acid in the first distilling tower until the concentration of hydrogen fluoride in distillate is higher than the concentration of recovered fluoric acid to obtain refined fluoric acid.

Description

technical field [0001] The present invention relates to a method for recovering hydrofluoric acid, and more specifically, relates to a method for recovering hydrofluoric acid in a batch method for recovering and refining hydrofluoric acid from hydrofluoric acid waste liquid containing metal components discharged from an etching process of a glass substrate, etc., by a distillation method . 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 using hydrofluoric acid such as etching described above, hydrofluoric acid waste liquid containing metal components is discharged, but such waste liquid contains a large amount of hydrofluoric acid not used in the r...

Claims

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Application Information

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IPC IPC(8): C01B7/19
Inventor 宫田坚洋亀山薰川瀬泰人
Owner MITSUBISHI CHEM ENG CORP
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