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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 easy precipitation Effect

Active Publication Date: 2020-12-22
PANGANG GROUP RESEARCH INSTITUTE CO LTD
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  • Abstract
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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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  • Preparation method of soluble chromium hydroxide

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preparation example Construction

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

[0029] Step 1: adding ammonium salt to the trivalent chromium solution and dissolving it to obtain the first mixed solution;

[0030] 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] Step 3: Filter and wash the precipitated chromium hydroxide to obtain easily soluble chromium hydroxide, and the filtrate can directly enter the waste water treatment process.

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

Embodiment 1

[0038] Chromium chloride solution 1000mL (where 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 300r / min, controlling the end point pH to be 6.0, and stirring and reacting for 30 minutes after adding alkali; filtering and washing to obtain soluble hydrogen Chromium oxide, the filtrate enters the wastewater treatment process. The obtained chromium hydroxide precipitate was placed in 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 (where Cr 3+ =26g / L), add ammonium sulfate 132g (n(NH 4+ ):n(Cr 3+ )=2.0), stir and dissolve; add sodium carbonate lye at a temperature of 60°C and a stirring speed of 400 to 500r / min, control the end point pH to 7.0, and complete the stirring reaction for 15 minutes after adding alkali; filter and wash to obtain soluble hydroxide Chromium, the filtrate enters the wastewater treatment process. Place the obtained chromium hydroxide precipitate in 0.05mol / L H 2 SO 4 solution (2000mL), stirring and dissolving at room temperature, the required time is about 5min.

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Abstract

The invention discloses a preparation method of soluble chromium hydroxide. The preparation method comprises the following steps: adding ammonium salt into a trivalent chromium solution and dissolvingthe ammonium salt to obtain a first mixed solution; under a preset reaction condition, adding alkali into the first mixed solution to obtain a chromium hydroxide precipitate; and filtering and washing the chromium hydroxide precipitate to obtain the soluble chromium hydroxide. By adding the ammonium salt into the trivalent chromium solution, the precipitation speed of trivalent chromium is reduced in the alkalifying process, the generation of a chromium hydroxide colloid is inhibited, and the soluble chromium hydroxide is prepared; on the basis of traditional alkali precipitation, only singleammonium salt needs to be added, and the adding amount the ammonium salt is small, so cost is low, and other impurities are not introduced; the process of the method is simple, reaction conditions are mild, and operability is high; and chromium hydroxide is easy to precipitate, does not need standing, can be easily dissolved in acid, and can be used as a trivalent chromium source 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 soluble chromium hydroxide. Background technique [0002] In recent years, the application of trivalent chromium in electroplating and metal surface treatment has flourished. The source of trivalent chromium in 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, in use, as chromium is deposited on the substrate in the form of metallic chromium or chromium oxide, Cl - or SO 4 2- The anions will remain in the bath liquid; after supplementing the chromium source equivalent to the amount of chromium consumed to continue electroplating, the anions will continue to accumulate in the bath, making the composition of the bath liquid unable to maintain stability. for disposal. Although chromi...

Claims

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Application Information

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Patent Type & Authority Applications(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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