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Separation method and separation device

A separation method and separation technology, applied in the direction of fluorine/hydrogen fluoride, etc., can solve problems such as inability to perform efficient recovery, many processes, and generation of secondary waste liquid

Inactive Publication Date: 2014-12-03
SEIKO EPSON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, in this method, hydrofluoric acid cannot be directly separated and recovered from the etching solution.
That is, after recovering as calcium fluoride, it is necessary to convert the calcium fluoride into hydrofluoric acid, so efficient recovery cannot be performed.
In addition, there are many steps from the etching waste liquid to the production of new etching liquid (hydrofluoric acid), and a large amount of secondary waste liquid is generated in the process.
Therefore, there is also the problem of poor environmental performance
In addition, due to many steps, there is also a problem that the device structure is enlarged and complicated

Method used

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Experimental program
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Effect test

Embodiment 1

[0120] A mixed acid was prepared as an etching waste solution. In addition, the concentration of hydrofluoric acid before separation of this mixed acid was 12.6 wt%, the concentration of ammonium bifluoride before separation was 27.6 wt%, the concentration before separation of silicon was 0.4 wt%, and the remainder was almost all water. These concentrations were measured using the above-mentioned apparatus and method (the same applies to the concentrations described below).

[0121] First Distillation Process

[0122] 500 g of mixed acids were charged into a distillation pot, and distillation was performed by heating the mixed acids to 120° C. under atmospheric pressure. Thus, hydrofluoric acid (hydrofluoric acid aqueous solution) was obtained as distillate A. This process was performed until the distillation amount reached 60%, whereby 297 g of distillate A was obtained.

[0123] As a result of measuring the concentration of each component in the distillate A, the concentr...

Embodiment 2

[0135] A mixed acid was prepared as an etching waste solution. In addition, the concentration of hydrofluoric acid in this mixed acid is 16.8 wt%, the concentration of ammonium bifluoride is 31.2 wt%, the concentration of silicon is 0.11 wt%, and the rest is almost all water.

[0136] First Distillation Process

[0137] Next, 500 g of the mixed acid was charged into the distillation pot, and the mixed acid was heated to 120° C. under atmospheric pressure to perform distillation. Thus, hydrofluoric acid (hydrofluoric acid aqueous solution) was obtained as distillate A'. This process was carried out until the distillation amount reached 65%, whereby 322 g of distillate A' was obtained.

[0138] As a result of measuring the concentration of each component in the distillate A', the concentration of hydrofluoric acid was 18.2 wt%, the concentration of ammonium bifluoride was 0.01 wt%, and the concentration of silicon was 0.01 wt%. The yield of hydrofluoric acid to the mixed acid...

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Abstract

The invention provides a separation method and a separation device, which can simply separate high-purity hydrofluoric acid from a mixed acid at least containing hydrofluoric acid, ammonium bifluoride, silicon and water. The separation method of separating the hydrofluoric acid from the mixed acid (100) at least containing hydrofluoric acid, ammonium bifluoride, silicon and water, comprises the following steps: a first distillation step of distilling the mixed acid (100) to recover a distillate (200) containing the hydrofluoric acid and water and recover a residual fluid (500) containing the ammonium bifluoride and the silicon; a second distillation step of distilling the distillate (200) to mainly separate water from the distillate (200) and furthermore recover a residual fluid (600) containing the hydrofluoric acid with relatively higher concentration than that of the hydrofluoric acid in the distillate (200).

Description

technical field [0001] The invention relates to a separation method and a separation device. Background technique [0002] Conventionally, products containing hydrofluoric acid and ammonium fluoride are known as etching solutions. In addition, a technique for recovering hydrofluoric acid (fluorine) from such an etching solution and an etching waste solution used after etching is also widely known (for example, refer to Patent Document 1). [0003] Patent Document 1 describes a method of recovering fluorine as high-purity calcium fluoride with a low silica content by reacting calcium carbonate with an etching solution containing hydrofluoric acid and ammonium fluoride, Hydrofluoric acid for etching solution is produced again from the recovered calcium fluoride. [0004] However, in this method, hydrofluoric acid cannot be directly separated and recovered from the etching solution. That is, after recovering as calcium fluoride, a step of converting the calcium fluoride into...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B7/19
Inventor 山本秀树
Owner SEIKO EPSON CORP