Aqueous solution of chromium salt and method for producing same

A manufacturing method and aqueous solution technology, applied in chemical instruments and methods, chromate/dichromate, metal material coating technology, etc., can solve problems such as danger and NOx

Active Publication Date: 2006-12-27
NIPPON CHECMICAL IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, depending on the conditions, the added reducing agent reacts with nitric acid instead of chromium trioxide, and as a result, NOx may be generated
Therefore, not only a deNOx device is required, but also a dangerous state may be caused by violent reaction

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-1

[0070] In a glass reaction vessel equipped with a condenser, 251.6 g of water was added, and then 253.1 g of chromium trioxide was added, fully stirred and dissolved to form a 50% chromic acid aqueous solution. As a reducing agent, methanol was used. As the first stage of the reaction, a 20% aqueous methanol solution in which 48.4 g of water was added to 12.2 g of 99.5% methanol was added to the chromic acid aqueous solution at a rate of 1.0 g / min using a metering pump. This addition rate was the rate at which 60.6 g of 20% methanol aqueous solution was added in about 1 hour. In addition, 12.2 g of 99.5% methanol is an amount equivalent to reducing 30% of chromic acid.

[0071] After the first-stage addition of the reducing agent was completed, 817.9 g of a mixed solution of 28.4 g of 99.5% methanol and 789.5 g of 35% hydrochloric acid was added at a rate of 6.8 g / min. This addition rate was the rate at which the mixed solution of 817.9 g of methanol and hydrochloric acid wa...

Embodiment 1-2

[0076] Into a glass reaction container equipped with a condenser, 420.6 g of 60% chromic acid aqueous solution and 84.1 g of water were added and fully stirred to obtain a 50% chromic acid aqueous solution. As a reducing agent, ethylene glycol is used. As the first stage of the reaction, a 20% ethylene glycol aqueous solution in which 56.2 g of water was added to 14.3 g of 98.5% ethylene glycol was added to the chromic acid aqueous solution at a rate of 1.2 g / min using a metering pump. This addition rate is a rate of adding 70.5 g of 20% ethylene glycol aqueous solution in about 1 hour. In addition, 14.3 g of 98.5% ethylene glycol is an amount equivalent to reducing 30% of chromic acid.

[0077] After the addition of the reducing agent in the first stage was completed, 822.9 g of a mixed solution of 33.4 g of 98.5% ethylene glycol and 789.5 g of 35% hydrochloric acid was added at a rate of 6.9 g / min. This addition rate was the rate at which the mixed solution of 822.9 g of e...

Embodiment 1-3

[0080] Into a glass reaction container equipped with a condenser, 420.6 g of 60% liquid chromic acid and 151.1 g of water were added and fully stirred to obtain a 44% chromic acid aqueous solution. As reducing agent, 99.5% methanol was used. As the first stage of the reaction, a 20% aqueous methanol solution in which 48.4 g of water was added to 12.2 g of 99.5% methanol was added to the chromic acid aqueous solution at a rate of 1.0 g / min using a metering pump. This addition rate was the rate at which 60.6 g of 20% methanol aqueous solution was added in about 1 hour. In addition, 12.2 g of 99.5% methanol is an amount equivalent to reducing 30% of chromic acid.

[0081] After the first-stage addition of the reducing agent was completed, 423.2 g of a mixed solution of 28.4 g of 99.5% methanol and 394.8 g of 35% hydrochloric acid was added at a rate of 3.5 g / min. This addition rate was the rate at which 423.2 g of methanol and hydrochloric acid mixed solution were added in 2 ho...

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PUM

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Abstract

Disclosed is an aqueous solution of a chromium salt which is characterized in that the oxalic acid content is not more than 8 weight% relative to chromium. In this aqueous solution of a chromium salt, the total organic carbon is not more than 4 weight% relative to chromium. The chromium salt may preferably be a chromium chloride, a chromium phosphate or a chromium nitrate. The chromium chloride may preferably contain a basic chromium chloride represented by the following composition formula: Cr(OH)xCly (wherein 0 < x <= 2, 1 <= y < 3, and x + y = 3). The chromium phosphate may preferably be one represented by the following composition formula: Cr(H3-3 / nPO4)n (wherein n is a number satisfying 2 <= n <= 3). The chromium nitrate may preferably be a basic chromium nitrate represented by the following composition formula: Cr(OH)x(NO3)y (wherein 0 < x <= 2, 1 <= y < 3, and x + y = 3).

Description

technical field [0001] The present invention relates to chromium salt aqueous solution and its preparation method. Background technique [0002] Among various chromium salt aqueous solutions, it is known that an aqueous chromium nitrate solution can be used as a surface treatment agent for metals. An aqueous solution of chromium phosphate can be used as a treatment solution for forming a chemical protective film on the surface of various metals such as iron, nickel, copper, etc. to be galvanized (see Patent Document 1). [0003] At present, as the production method of chromium salts such as chromium nitrate, chromium phosphate, chromium chloride, etc., the known method is to add sulfuric acid to the sodium dichromate solution obtained by alkali oxidation and roasting of ore, and reduce it with organic matter. And become chromium sulfate solution, add sodium hydroxide or anhydrous sodium carbonate therein, produce the precipitation of chromium hydroxide or chromium carbonate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14C23C22/27C23C22/30C01B25/37
Inventor 小泷秀树番田知宏原孝志高木伸夫
Owner NIPPON CHECMICAL IND CO LTD
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