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Chromium residue detoxifying process

A chromium slag and process technology, applied in the field of chromium slag detoxification, can solve the problems of not finding a chromium slag detoxification process, long detoxification reduction time, harsh reaction conditions, etc., so as to extend the effective reduction reaction time, shorten the redox reaction time, Overcome the effects of low temperature

Inactive Publication Date: 2011-08-31
河南金谷环保工程设备有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, sodium chromate tetrahydrate and free calcium chromate are water-soluble phases, which are easily dissolved by surface water and rainwater, which is the source of the recent pollution of chromium slag; although the other four components are difficult to dissolve in water, they can be stored in the open air for a long time. After weathering and hydration, it is easy to cause medium and long-term pollution of the environment by chromium slag
[0003] Chromium slag detoxification has always been a headache for the chromium salt industry. Traditional detoxification methods have not found a truly effective, An Economical and Operable Chromium Slag Detoxification Process

Method used

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Examples

Experimental program
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Embodiment 1

[0047] Process flow chart as shown in the accompanying drawing:

[0048] In the first step, chromium slag and reducing agent 1 are placed in a wet ball (rod) mill, ground and pulverized to 200 mesh, water-soluble and acid-soluble hexavalent chromium (Cr 6+ ) continuously dissolves, and the dissolved water-soluble (Cr 6+ ) continuously undergoes the first reduction reaction with reducing agent 1 to convert to trivalent chromium (Cr 3+ ), to detoxify the chromium slag initially. Among them, reducing agent 1 is sodium sulfide (Na 2 S), its dosage is to reduce 90% of the total amount of hexavalent chromium in the measured chromium slag to trivalent chromium as a criterion.

[0049] In the second step, the chromium slag after preliminary detoxification in the first step is put into the beating tank, and circulating water is introduced into the beating tank to prepare the chromium slag slurry, and the concentration is controlled to be 40 Baume degrees, and then the chromium slag ...

Embodiment 2

[0052] The difference with Example 1 is: in the second step, the mass concentration of concentrated sulfuric acid is 98%; in the third step, after solid-liquid separation, an alkaline substance NaOH is added in the obtained filtrate 1 to adjust the pH of the filtrate 1 The value is up to 6, and the Mg in it is to be measured 2+ 、Al 3+ , Fe 3+ 、Cr 3+ After the precipitation, the solid-liquid separation is performed again, and the obtained filtrate 2 is returned to the wet ball (rod) mill and the beating tank for recycling; the others are the same as in Example 1.

Embodiment 3

[0054] The difference from Example 1 is that in the third step, after solid-liquid separation, an alkaline substance CaO is added to the obtained filtrate 1 to adjust the pH value of the filtrate 1 to 8, and the Mg therein is to be measured. 2+ 、Al 3+ , Fe 3+ 、Cr 3+ and SO 4 2- After the precipitation, the solid-liquid separation is performed again, and the obtained filtrate 2 is returned to the wet ball (rod) mill and the beating tank for recycling; the others are the same as in Example 1.

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Abstract

The invention belongs to the technical field of chromium residue detoxifying, and discloses a chromium residue detoxifying process. The process comprises the following steps of: performing wet grinding on chromium residue, adding water into the chromium residue to prepare chromium residue slurry; and after being subjected to acid-leaching reduction reaction, performing solid-liquid separation on the chromium residue slurry to obtain a filter cake, namely the detoxified chromium residue. The process is characterized in that: under the condition of not changing the original alkaline environmentof the chromium residue, a reducing agent 1 is added into the chromium residue directly, and then the reducing agent and the chromium residue are subjected to wet grinding to form particles with 100 to 300 meshes; and the water is added to prepare the chromium residue slurry with 30 to 45 baume degrees, wherein the reducing agent 1 is sodium sulphide, sodium bisulfide, sodium thiosulfate or sodium pyrosulfite. The process has simpleness, thorough detoxification, no chromium return phenomenon and easy implementation of mass production; and the process prolongs effective reduction reaction time, improves reaction efficiency, saves the using amount of acid during the acid-leaching reduction, and has low processing cost because Cr6+ in the chromium residue is subjected to two times of dissolution and reduction.

Description

technical field [0001] The invention belongs to the technical field of chromium slag detoxification, and in particular relates to a chromium slag detoxification process. Background technique [0002] The chromium salt industry is an indispensable and important industry in the national economy, mainly used in electroplating, leather tanning, printing and dyeing, medicine, catalyst, metal corrosion inhibition, etc. The main waste residue (ie, chromium residue) discharged during the production of chromium salts is a highly toxic hazardous waste, of which hexavalent chromium (Cr 6+ ) is the source of toxicity. According to the analysis results of the chemical composition characteristics of some chromium slags in my country, Cr 2 o 3 For measurement, the average mass percentage of total chromium in the chromium slag is about 3-5%, and the average mass percentage of hexavalent chromium is about 1-5%. There are six components in chromium slag containing Cr 6+ , respectively so...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A62D3/37
Inventor 李顺灵陈俊杰杨秋岭黄立志袁明涛李万灵燕战军赵豆豆李常慧张鋆浩潘志恒杨海龙
Owner 河南金谷环保工程设备有限公司
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