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Method for producing chromates through using chromium-containing waste residues

A technology of chromium waste residue and chromate, which is applied in the direction of chromate/dichromate, etc., to achieve the effect of solving environmental pollution, simple process flow and low process cost

Active Publication Date: 2013-12-18
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The purpose of the present invention is to overcome a series of problems in the existing chromate production process and provide a new raw material source and production process for the production of chromate

Method used

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  • Method for producing chromates through using chromium-containing waste residues

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Embodiment 1

[0056] First, a chromium-containing waste slag (dry basis, Cr content 25-30%, V content 0-0.5%, Si content 15-20%) produced during the process of vanadium extraction by vanadium-titanium magnetite was mixed with a concentration of 30 %Na 2 CO 3 The solution was reacted for 4 hours under the conditions of a liquid-solid ratio of 4:1, an oxidant of oxygen, an oxygen pressure of 5atm, and a temperature of 180°C, and the chromium leaching rate was 98%. The leached mixed slurry is filtered and separated to obtain filter cake (II) and chromate-containing alkali solution, and the chromate-containing alkali solution is evaporated and crystallized, and solid-liquid separation is performed to obtain sodium carbonate and sodium chromate crystals. The evaporative crystallization is operated under normal pressure, the initial temperature is 40°C, and the final temperature is 60°C.

Embodiment 2

[0058] Firstly, the chromium-containing waste residue (dry basis, Cr content 25-30%, Al content 0-2%, soluble sulfate 5-10%) of a chromium salt plant water treatment sludge is washed with water slurry, and the liquid-solid ratio (i.e. the mass ratio of the washing solution to the chromium-containing waste residue) is 8:1, and then the filter cake (I) and the washing solution are respectively obtained after gravity sedimentation; the filter cake (I) and the concentration of 75% K 2 CO 3 The solution was reacted for 3 hours under the conditions of a liquid-solid ratio of 10:1, an oxidant of oxygen, an oxygen pressure of 15atm, and a temperature of 150°C, and the chromium leaching rate was 98%. After leaching, the slurry is filtered and separated after impurity removal and desiliconization to obtain filter cake and leachate. The filter cake is washed to obtain non-toxic waste residue; the leaching solution is evaporated and crystallized, and solid-liquid separation is performed ...

Embodiment 3

[0060] Firstly, a chromium-containing waste residue (dry basis, Cr content 15-20%, organic matter content 20-30%, Fe content 0.1-1%) produced by the pharmaceutical industry was ground to a particle size of 20 μm, and the concentration was 10% NaOH countercurrent slurry washing, the liquid-solid ratio (that is, the mass ratio of the washing liquid to the chromium-containing waste residue) is 3:1, and then the filter cake (I) and the washing liquid are obtained after centrifugation, and the washing liquid is evaporated and crystallized to precipitate water-soluble Salt crystals, the secondary steam is condensed and recycled; the filter cake (I) and the NaOH solution with a concentration of 30% are in a liquid-solid ratio of 3:1, the oxidant is oxygen, the oxygen pressure is 2atm, and the temperature is 250°C Under the condition of reaction for 4 hours, the chromium leaching rate is 99%. After leaching, the mixed slurry is centrifuged to obtain filter cake (II) and chromate-conta...

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Abstract

The invention relates to a method for producing chromates through using chromium-containing waste residues. The method comprises the following steps: reacting pretreated chromium-containing waste residues with an oxidant in an alkaline solution, removing impurities of an obtained reaction solution, carrying out evaporative crystallization, and carrying out solid-liquid separation to obtain chromate products. The chromium-containing waste residues mainly comprise chromium hydroxide-containing waste residues and concretely are industrial chromium-containing wastes generated in the industrial processes comprising the metallurgy, the chemical industry, the pharmacy, the light industry and the like, wherein the main occurrence states of chromium comprise trivalent chromium salts, chromium hydroxide or hydrates thereof. The method has the advantages of short process flow, mild condition, small apparatus corrosion, low process cost, realization of the circulating regeneration of the chromium-containing waste residues, environmental pollution solving, exploitation of a new raw material for producing the chromates, and economic value creation.

Description

technical field [0001] The invention belongs to the field of hydrometallurgy or solid waste treatment, and in particular relates to a method for producing chromate from waste slag containing chromium with low energy consumption, no pollution and advanced technology. Background technique [0002] Chromate is an industrially necessary chemical raw material. As a chemical raw material for the preparation of chromium-based products such as sodium red alum, chromic anhydride, and chromium powder, it is widely used in metallurgy, materials, corrosion and protection. At present, the source of chromate production at home and abroad is mainly chromite ore. The crystal structure of chromite is a spinel structure, and a high activation energy is required to destroy this spinel structure, and most of the chromite is an associated ore, which often contains magnesium, aluminum, silicon and other impurities. There are disadvantages such as high reaction temperature, high pressure, and lo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 徐红彬张小飞张洋王念卫裴丽丽瞿金为张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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