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Method for preparing high-purity chromium powder through electrochemical reduction of trivalent chromium by using ionic exchange membrane cell

An ion-exchange membrane electrolyzer and electrochemical technology, applied in the field of non-ferrous metallurgy, can solve problems such as difficulty in achieving continuous deposition of coatings, inapplicability to large-scale industrial production, and inconvenient control of production conditions, and achieve low raw material prices and simple composition , No environmental pollution effect

Active Publication Date: 2014-12-10
HARBIN INST OF TECH AT WEIHAI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The metal thermal reduction method is suitable for large-scale production. It is characterized in that it is generally used in a special container to reduce chromium ions with a metal reducing agent under an inert gas protective atmosphere, but the presence of other metal ions is likely to cause pollution to the product.
Although the vacuum carbon reduction method can avoid pollution to the product, it is inconvenient to control the production conditions, and the energy consumption is high, so it is not suitable for large-scale industrial production
Compared with the previous two methods, the electrolysis method has the advantages of easy control of the production conditions and high purity of the obtained product, but its biggest disadvantage is the low current efficiency (about 10~40%) and high energy consumption, and it is difficult to achieve continuous deposition of the coating

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Embodiment 1: A method for producing high-purity chromium powder by electrochemically reducing trivalent chromium in an ion-exchange membrane electrolyzer. The cathode is a red copper plate, and the anode is insoluble graphite; It is an anion exchange membrane; the distance between cathode and ion exchange membrane, anode and ion exchange membrane is 30 mm; the distance between cathode and anode is 60 mm; electrolysis time is 1 h; current density is 600 A m -2 ; Electrolytic stirring speed is 0 rpm.

[0033] Take 500 ml of a solution composed of chromium chloride, boric acid, amide compounds and carboxylate compounds as catholyte, wherein Cr 3+ The concentration is 30 g·L -1 ;Another 500 ml of sodium hydroxide solution was taken as the anolyte; the electrolysis temperature was 27°C; 99.85% pure.

Embodiment 2

[0034] Embodiment 2: A method for electrochemically reducing trivalent chromium in an ion-exchange membrane electrolyzer to produce high-purity chromium powder. The electrode, electrolyzer structure, electrode diaphragm, and electrode distance are the same as in Embodiment 1. Electrolysis time 2 h; current density 800 A m -2 ; Electrolytic stirring speed is 900 rpm.

[0035] Take 500 ml of a solution composed of chromium chloride, boric acid, amide compounds and carboxylate compounds as catholyte, wherein Cr 3+ The concentration is 30 g·L -1 ;Another 500 ml of sodium hydroxide solution was used as the anolyte; the electrolysis temperature was 30°C; the average cell pressure was 3.84 V; the current efficiency was 80.2%; the metal chromium obtained on the cathode of the cathode chamber was in the form of powder, and the quality of the chromium powder was 0.7472g; The purity is 99.62%.

Embodiment 3

[0036] Embodiment 3: A method for electrochemically reducing trivalent chromium in an ion-exchange membrane electrolyzer to produce high-purity chromium powder. The electrode, electrolyzer structure, electrode diaphragm, and electrode distance are the same as in Embodiment 1. Electrolysis time 4 h; current density 300 A m -2 ; Electrolytic stirring speed is 1200 rpm.

[0037]Take 500 ml of a solution composed of chromium chloride, boric acid, amide compounds and carboxylate compounds as catholyte, wherein Cr 3+ The concentration is 20 g·L -1 ; Another 500 ml of sodium hydroxide solution is taken as the anolyte; the electrolysis temperature is 40 ℃; the average cell voltage is 6.38V; the current efficiency is 71.2%; The purity is 99.57%.

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Abstract

The invention relates to a method for preparing high-purity chromium powder through electrochemical reduction of trivalent chromium by using an ionic exchange membrane cell. Used catholyte is a composite solution containing chromic chloride, boric acid, amides compounds and carboxylic acid or carboxylate compounds, anolyte is a low valence state metal oxysalt solution or metal alkaline solution, and an electrolytic cell separation membrane is an anion-exchange membrane. A negative pole for electrolysis is a simple substance or a reduced metal panel, and a positive pole for the electrolysis is low valence state metal or an insoluble graphite panel. Electric current density is 100-1000A.m-2. Electrolytic cell pressure is 0.5-10V. Electrolysis temperature is 10-60 DEG C. Electrolysis stirring speed is 0-2,400rpm. According to the method, as the composite solution containing materials such as Cr3+ is used to conduct the electrolysis, pollution of Cr6+ on environment in a traditional electrolysis process is avoided, the high purity chromium powder is obtained on the negative pole, current efficiency of the negative pole is substantially improved, the current efficiency of the negative pole can be higher than 60%, and energy consumption for electrolytic deposition chromium powder is reduced.

Description

technical field [0001] The invention relates to the field of nonferrous metal metallurgy, in particular to a method for preparing high-purity chromium powder by electrochemically reducing trivalent chromium in an ion-exchange membrane electrolyzer. Background technique [0002] As the hardest element in the earth's crust, chromium is widely used in the field of metal surface treatment. At present, the United States, Japan, and most countries and regions in Europe have formulated strict policies, regulations and standards for the use and emission of hexavalent chromium, strictly controlling its emission, and using it within a limited period until the prohibition of hexavalent chromium and cyanide electroplating products enter the market. Therefore, the traditional hexavalent chromium reduction process will inevitably be eliminated. [0003] CN 101260537B discloses a "method for producing high-purity metal chromium by electrolysis", which uses hexavalent chromium ions as obj...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25C5/02
Inventor 魏琦峰姚远任秀莲
Owner HARBIN INST OF TECH AT WEIHAI