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Method for separating and recovering chromium from waste residue containing hexavalent chromium

A technology of separation and recovery of hexavalent chromium, which is applied to the removal of solid waste, chemical instruments and methods, water/sewage treatment, etc., can solve the problems of troublesome post-treatment of filter residue, unsatisfactory leaching effect, and difficult solid-liquid separation. Achieve the effect of complete detoxification, high social and economic benefits, and simple process

Active Publication Date: 2008-07-02
FUJIAN INST OF RES ON THE STRUCTURE OF MATTER CHINESE ACAD OF SCI
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chinese patent "Chromium leaching slag treatment process" (CN1085832A), "Chromium slag water-dissolved poison comprehensive utilization method" (CN1201836A) directly leaching soluble hexavalent chromium with water, Chinese patent "alkaline chromium leaching slag treatment process" (CN1110196A) in Before leaching chromium with water, sodium carbonate is used to convert the calcium chromate in the chromium slag into sodium chromate to improve the leaching efficiency, but it is difficult to leaching the fine-grained hexavalent chromium-containing waste slag by these methods, even if the chromium leaching rate is heated and stirred also very low
This method produces a large amount of hydroxide colloids after neutralization, making solid-liquid separation more difficult
The Chinese patent "Comprehensive Utilization Method for Detoxification of Chromium Slag" (CN1038771A) has been improved, and most of the acidic hexavalent chromium in the chromium residue is leached with dilute hydrochloric acid, but the leaching effect of this method for the fine particle containing hexavalent chromium waste residue is also low. Not ideal, plus consumes a lot of acid
[0006] The flocculant method is used to recover chromium, that is, after the chromium slag is mixed with water and boiled evenly, the flocculant is added to the chromium slag suspension to increase the chromium slag particles and settle rapidly. The post-processing work caused trouble

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 1) Take 0.5 tons of waste residue containing hexavalent chromium and put it into a hydrothermal kettle with a solid-to-liquid ratio of 1:5, add Na 2 CO 3 50kg and NaHCO 3 420kg, stir fully, close the water heating kettle, set the temperature at 160°C, and keep it warm for 18 hours.

[0031] 2) After the hydrothermal treatment, pour out the solution containing hexavalent chromium in the upper layer, and take out the crystalline salt for the next hydrothermal treatment. Centrifugal washing and dehydration is carried out on the slag treated by the hydrothermal method, and the filter residue is dried.

[0032] 4) Collect the chromium-containing solution in the wastewater treatment station for reduction, recovery, and purification treatment, and add a reducing agent (such as sodium sulfide, sodium bisulfite, etc.) to reduce the hexavalent chromium in the solution to trivalent chromium to generate Cr (OH) 3 Sedimentation, the treated water can meet the national drainage ...

Embodiment 2

[0036] Take 1 ton of waste residue containing hexavalent chromium and put it into a hydrothermal kettle with a solid-to-liquid ratio of 1:2, add NaHCO 3 680kg, stir fully, close the water heating kettle, set the temperature at 130°C, and keep warm for 10 hours. Other technological process is identical with embodiment 1.

[0037]The original chromium slag contains 1210mg / kg of hexavalent chromium, and the acid-soluble hexavalent chromium after treatment is 2.984mg / kg.

Embodiment 3

[0039] Take 1.5 tons of hexavalent chromium-containing waste residue and put it into a hydrothermal kettle with a solid-to-liquid ratio of 1:1, add the crystalline salt generated by the previous hydrothermal treatment, and supplement NaHCO 3 300kg, stir fully, turn off the water heating kettle, set the temperature at 120°C, and keep it warm for 20 hours. Other technological process is identical with embodiment 1.

[0040] The original chromium slag contains 1632mg / kg of hexavalent chromium, and the acid-soluble hexavalent chromium after treatment is 3.214mg / kg.

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Abstract

The invention discloses a method for separating and recycling chromium from the waste residue containing hexavalent chromium. The waste residue containing hexavalent chromium which has fine particles and is difficult to subside is added with mineralizer and then is subject to hydrothermal method or heating treatment to generate the waste residue which can subside, the upper clear liquid is separated from the waste residue and then the waste residue is cleaned and dried. Sodium bicarbonate or salt-mixture of sodium carbonate and sodium bicarbonate is adopted as mineralizer. The invention has simple process, low cost, quick results, large throughput, complete detoxification and no secondary pollution and can make use of all the residue, thereby bringing comparatively high social benefit and economic benefit.

Description

technical field [0001] The method relates to a chromium separation, recovery and treatment method for waste residue containing hexavalent chromium. Background technique [0002] The hexavalent chromium-containing waste residue with fine particles (the particle size can reach the nanometer level), because of the fine particles, the hexavalent chromium ions are firmly adsorbed on the surface of the particles, and it is difficult to leach with water. However, when stacked in the open air, after long-term rain shower or soaking in stagnant water, a large amount of hexavalent chromium ions will dissolve with water and seep into the surface, thereby polluting groundwater, rivers and lakes, endangering aquatic products, farmland, various animals and plants, and further endangering human beings. . Chromium, on the other hand, is the number one strategic metal. Chromium and its compounds are widely used in various fields of industrial production, and are essential raw materials for...

Claims

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Application Information

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IPC IPC(8): C02F1/62B09B3/00
Inventor 林璋刘炜珍黄丰廖逸群庄赞勇
Owner FUJIAN INST OF RES ON THE STRUCTURE OF MATTER CHINESE ACAD OF SCI
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