Sodium cyanide process

A technology of sodium glycolate and solution, which is applied in the direction of metal cyanide and simple alkali metal cyanide, and can solve the problems of high transportation costs, accident leakage, environmental risks, etc.

Active Publication Date: 2006-05-03
THE CHEMOURS CO FC LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although transporting sodium cyanide solution is an alternative, it entails high transport costs and high environmental risk in the event of an accidental spill during transport

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Sodium cyanide from a typical composition solution of a commercial sodium cyanide production process was used in this example. This production method is disclosed in US Patent 4,847,062, incorporated herein by reference.

[0028] Sodium cyanide crystallization is performed in a small chamber that provides an optical path for the solution and the crystals formed. This chamber is similar to that invented by Garside and Larson. (J. Garside, A. Mersmann &, J. Nyvlt (eds.) Measurement of Crystal Growth Rates, 1990, European Federation of Chemical Engineering, Working Party on Crystallization, P. 83), the disclosure of which is hereby incorporated by reference for brevity . The chamber consists of a 15 cm3 solution tank contained between two glass plates. The upper plate is thicker and forms an insulating barrier, and the lower plate separates the crystallized solution from the constant temperature water that circulates through the device from a constant temperature bath. ...

Embodiment 2

[0037] This example shows the growth of sodium cyanide crystals in the presence of iron, with and without glycolate.

[0038] The same procedure as described in Example 1 was carried out except that iron was added as described below. The solution was saturated with sodium cyanide at 80°C. In this example, all crystallization onset temperatures were 60°C. In this example, additional iron was added to the plant mother liquor in the form of ferric chloride. The final concentration of iron added was 30 ppm (ppm, based on iron). After the solution was prepared, small brown spots settled to the bottom of the container, which appeared to be FeCl 3 . The mother liquor is thus saturated with iron, and 30 ppm of iron added exceeds the iron saturation concentration of the mother liquor.

[0039] One experiment was performed with iron added and without sodium glycolate. A second experiment was performed with the same iron concentration and with the addition of 2 wt% sodium glycolate...

Embodiment 3

[0044] In this example, 10ppm of ferric chloride (iron-based) and 2% sodium glycolate were added. After the solution was prepared, as in Example 2, small brown spots remained in the flask, which was probably undissolved chlorine Iron. The inventors again expected that in the mother liquor FcCl 3 The degree of saturation determines the actual concentration of iron. However, the inventors expect the actual concentration of excess iron to be less than 10 ppm in each case, and the value is the same whether 10 ppm or 30 ppm is added.

[0045] The results showed that the quality of the crystals was very close to that obtained by adding glycolate in Example 2. The measured crystal growth rate was 4 μm / min, slightly lower than that obtained in Example 2, but approximately the same within the expected measurement accuracy.

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PUM

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Abstract

The present invention provides a method for producing NaCN. The process comprises contacting hydrogen cyanide and sodium hydroxide to produce a NaCN solution, and crystallizing the NaCN solution, wherein the process is carried out in the presence of an acid or a metal salt of the acid, wherein the acid has a pKa≤4.8, from the slurry The NaCN crystals were isolated from and dried.

Description

field of invention [0001] The present invention relates to the crystallization method of sodium cyanide and the production method of sodium cyanide. Background of the invention [0002] Sodium cyanide (NaCN) has a variety of uses. For example, it can be used for electroplating, treating metal surfaces, extracting and recovering precious metals from ores, and many other chemical applications. The use of sodium cyanide in the leaching of ores containing precious metals, such as gold or silver, is well known in the art. [0003] To produce sodium cyanide, hydrogen cyanide (HCN) is neutralized with aqueous sodium hydroxide (NaOH) followed by evaporative crystallization to produce a slurry of sodium cyanide crystals which can be separated from the slurry and dried. During the crystallization of sodium cyanide from an aqueous solution, some liquid remains in the crystals producing an unwanted sodium cyanide. Additionally, the aqueous solution may contain c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01C3/10
CPCC01C3/10C01P2006/22
Inventor J·M·罗杰斯D·A·格林
Owner THE CHEMOURS CO FC LLC
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