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Method for removing cyanide in waste cathode carbon in aluminum electrolysis cell

An aluminum electrolytic cell waste and cyanide technology, which is applied in the removal of solid waste and other directions, can solve the problems of complex process flow and high processing cost, and achieve the effects of high oxidation efficiency, stable reaction, and convenient large-scale industrial application.

Inactive Publication Date: 2016-07-20
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method needs to consume a large amount of alkali to adjust the pH of the solution to be alkaline, the process flow is relatively complicated, and the treatment cost is high; and chloride ions and hydroxide ions are introduced in the process of removing cyanide, so the waste water needs to be treated. Further processing to meet environmental protection requirements

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] The treatment of cyanide in the waste cathode carbon block of aluminum electrolytic cells (wherein the sodium cyanide content is calculated as 0.2%), specifically includes the following steps:

[0058] (1) Crushing and grinding: 1 kg of aluminum electrolytic cell waste cathode carbon block is ground to -2mm by a fine crusher, and finally ground by a ball mill, so that the particle size -0.074mm accounts for 85%;

[0059] (2) Water immersion filtration: add 1kg of the waste cathode carbon blocks ground in step (1) into water to form a slurry (the mass ratio of solid to liquid is 1:7). Carry out water immersion in the tank, stir and leaching for 1.5h, then filter, and obtain 6860mL filtrate for further processing;

[0060] (3) Oxidative evaporation crystallization: add 70g / L hydrogen peroxide 30mL, stabilizer 0.175g (wherein citric acid 0.07g, maleic acid 0.105g) and ZnO1.5g to the step (2) filtrate, at a temperature of 50°C, a rotating speed of 60r / min Under the conditi...

Embodiment 2

[0062] The treatment of cyanide in the waste cathode carbon block of aluminum electrolytic cells (wherein the sodium cyanide content is calculated as 0.2%), specifically includes the following steps:

[0063] (1) Crushing and grinding: 1 kg of aluminum electrolytic cell waste cathode carbon block is ground to -2mm by a fine crusher, and finally ground by a ball mill, so that the particle size -0.074mm accounts for 90%;

[0064] (2) Water immersion filtration: add 1kg of the waste cathode carbon blocks ground in step (1) into water to form a slurry (solid-to-liquid ratio: 1:8). immersion in water, stirred and leached for 2 hours, filtered, and 7900mL filtrate was obtained from the filter for further processing;

[0065] (3) Oxidation and evaporation crystallization: Add 35 mL of 60 g / L hydrogen peroxide, 0.2 g of stabilizer (including 0.06 g of citric acid, 0.09 g of maleic acid, and 0.05 g of ethylenediaminetetraacetic acid) to the filtrate of step (2), 0.7 g of catalyst CuO a...

Embodiment 3

[0067] The treatment of cyanide in the waste cathode carbon block of aluminum electrolytic cells (wherein the sodium cyanide content is calculated as 0.2%), specifically includes the following steps:

[0068] (1) Crushing and grinding: 1 kg of aluminum electrolytic cell waste cathode carbon block is ground to -2mm by a fine crusher, and finally ground by a ball mill, so that the particle size -0.074mm accounts for 90%;

[0069] (2) Water immersion filtration: add 1kg of the waste cathode carbon blocks ground in step (1) into water to form a slurry (solid-to-liquid ratio: 1:8). immersion in water, stirred and leached for 2 hours, filtered, and 7900mL filtrate was obtained from the filter for further processing;

[0070] (3) oxidation evaporation crystallization: add 60g / L hydrogen peroxide 35mL, stabilizer 0.175g (ammonium citrate 0.05g among them) to step (2) filtrate, CuO0.8g and Fe 3 o 4 0.6g, oxidize the cyanide in the solution in a stirred reactor under the conditions of...

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Abstract

The invention relates to a method for removing cyanide in waste cathode carbon in an aluminum electrolysis cell, and belongs to the technical field of aluminum electrolysis solid waste resource recycling. After being levigated, an aluminum electrolysis cell waste cathode carbon block is added in water to be immersed; filtering is conducted after immersing, and first filter liquor and first filter slag are obtained; the reaction is conducted at the temperature of 30 DEG C to 70 DEG C after hydrogen peroxide, a stabilizing agent and a catalyst are added in the first filter liquor; filtering is conducted after the reaction, and second filter liquor and second filter slag are obtained; the second filter liquor is evaporated, distilled water and a crystal substance are obtained, and an oxidative product is decomposed into utilizable gas (CO2 and NH3). Treatment of the waste cathode carbon block with high efficiency and low energy consumption is achieved through the cooperative effect of the hydrogen peroxide, the proper number of the catalyst and the proper number of the stabilizing agent. The technology is simple, controllability is high, closed-loop circulation is achieved, secondary pollution is avoided, the resource utilization rate is high, and large-scale industrial application is facilitated.

Description

Technical field: [0001] The invention relates to a method for removing cyanide in waste cathode carbon blocks of an aluminum electrolytic cell, and belongs to the technical field of recycling solid waste resources of aluminum electrolysis. technical background: [0002] During the production process of aluminum electrolysis, the cathode carbon block expands due to the penetration of impurities such as sodium and cryolite, which further causes damage to the electrolytic cell. Domestic aluminum electrolytic cells need to be overhauled when they are about 2000 days old. The waste cathode carbon blocks produced during the overhaul process are one of the main solid pollutants in the aluminum electrolysis industry. The statistical results of the fluorine balance survey of industrial aluminum electrolytic cells show that for every ton of electrolytic aluminum produced, about 10kg of waste cathode carbon blocks will be produced. Taking 2015 as an example, the output of electrolytic...

Claims

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Application Information

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IPC IPC(8): B09B3/00B09B5/00
CPCB09B3/00B09B5/00
Inventor 田忠良杨凯肖劲袁杰郭伟昌赖延清李劼
Owner CENT SOUTH UNIV
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