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A kind of preparation method of soluble chromium hydroxide

A technology of chromium hydroxide and solution, applied in chemical instruments and methods, chromium compounds, inorganic chemistry, etc., can solve the problems of high cost, harsh conditions, and poor working environment, and achieve low cost, mild reaction conditions, and less addition Effect

Active Publication Date: 2022-07-08
PANGANG GROUP RESEARCH INSTITUTE CO LTD
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Problems solved by technology

The method for preparing soluble chromium hydroxide mentioned in this document is all realized under the condition of room temperature and below, prepares soluble chromium hydroxide with ammonia as precipitant, the cost is higher, and the working environment is relatively poor, and adopts When sodium hydroxide is used as a precipitant, it needs to be controlled at low temperature (<15°C), and the conditions are relatively harsh

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  • A kind of preparation method of soluble chromium hydroxide

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[0028] like figure 1 As shown, some embodiments of the present invention disclose a preparation method of soluble chromium hydroxide, comprising the following steps:

[0029] Step 1 adds ammonium salt to the trivalent chromium solution and dissolves to obtain the first mixed solution;

[0030] In step 2, under predetermined reaction conditions, alkali is added to the first mixed solution to obtain chromium hydroxide precipitation, and the ammonia released during the precipitation process can be absorbed and reused;

[0031] In step 3, the chromium hydroxide precipitate is filtered and washed to obtain easily soluble chromium hydroxide, and the filtrate can directly enter the wastewater treatment process.

[0032] Wherein, the ammonium salt is water-soluble and has a pH value of not more than 7; the ammonium salt can be one of ammonium sulfate, ammonium hydrogen sulfate, ammonium chloride, ammonium nitrate, and ammonium acetate. In some preferred embodiments, the anion of the...

Embodiment 1

[0038] Chromium chloride solution 1000mL (including Cr 3+ =10g / L), add ammonium chloride 6.2g (n(NH 4+ ):n(Cr 3+) = 0.6), stirring and dissolving; adding sodium bicarbonate lye at a temperature of 20 ° C and a stirring speed of 200 to 300 r / min, controlling the pH of the endpoint to be 6.0, and stirring the reaction for 30 min after adding alkali; filtering and washing to obtain easily soluble hydrogen Chromium oxide, the filtrate enters the wastewater treatment process. The obtained chromium hydroxide precipitate was placed in a 0.1 mol / L HCl solution (1000 mL), stirred and dissolved at room temperature, and the required time was about 3 min.

Embodiment 2

[0040] Chromium sulfate solution 2000mL (including Cr 3+ =26g / L), add ammonium sulfate 132g (n(NH 4+ ):n(Cr 3+ )=2.0), stirring and dissolving; adding sodium carbonate lye at a temperature of 60 ° C and a stirring speed of 400 to 500 r / min, controlling the pH of the endpoint to be 7.0, and adding alkali to complete the stirring reaction for 15 min; filtering and washing to obtain easily soluble hydrogen peroxide Chromium, the filtrate enters the wastewater treatment process. The obtained chromium hydroxide precipitate was placed in 0.05mol / L H 2 SO 4 The solution (2000 mL) was stirred and dissolved at room temperature, and the required time was about 5 min.

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Abstract

The invention discloses a preparation method of easily soluble chromium hydroxide, which comprises adding ammonium salt to a trivalent chromium solution and dissolving to obtain a first mixed solution; under predetermined reaction conditions, adding alkali into the first mixed solution to obtain chromium hydroxide precipitate; filter and wash the chromium hydroxide precipitate to obtain soluble chromium hydroxide. In the present invention, by adding ammonium salt to the trivalent chromium solution, the precipitation speed of trivalent chromium is slowed down in the process of adding alkali, the formation of chromium hydroxide colloid is suppressed, and a kind of soluble chromium hydroxide is prepared; On the basis of ammonium chloride, only a single ammonium salt needs to be added, the amount of addition is small, the cost is low, and no other impurities are introduced; the process is simple, the reaction conditions are mild, and the operability is strong; chromium hydroxide is easy to precipitate, no need to stand, easy to dissolve in acid, Can be used as a source of trivalent chromium for electroplating and metal surface treatment.

Description

technical field [0001] The invention relates to the technical field of metallurgy and chemical industry, in particular to a preparation method of easily soluble chromium hydroxide. Background technique [0002] In recent years, the application of trivalent chromium in electroplating and metal surface treatment has flourished. The trivalent chromium source of trivalent chromium electroplating baths and metal surface treatment pools mainly uses soluble trivalent chromium salts, such as chromium chloride, chromium sulfate, Chromium sulfamate, etc. However, as chromium is deposited on the substrate in the form of metallic chromium or chromium oxide during use, Cl - or SO 4 2- The anions will remain in the bath liquid; after the chromium source equivalent to the amount of consumed chromium is added to continue electroplating, the anions will continue to accumulate in the bath, so that the composition of the bath liquid cannot be kept stable. dispose of. Although chromium hyd...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/00
CPCC01G37/00Y02P10/20
Inventor 蒋霖伍珍秀李明伍金树
Owner PANGANG GROUP RESEARCH INSTITUTE CO LTD
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