A kind of harmless disposal method of wet chromium slag

Abstract

The invention discloses a method for harmless disposal of wet chromium slag. The device includes a pretreatment device, a No. 1 reaction device, a No. 2 reaction device, a No. 3 reaction device, a hexavalent chromium reduction device, a separation device, a washing device, Waste water treatment plant and middle water tank. First, after the chromium slag from the chromium slag stockyard is processed by the pre-treatment device, the wet chromium slag is sent to the No. 1 reactor, and the solution is slowly added into the No. 1 reactor, and the wet chromium slag is sent to the No. , mixed and sent to hexavalent chromium reduction device. Slowly add chromium reducing agent until the reduction is complete; liquid-solid separation is realized through the separation device; the liquid phase from the separation device is sent to the wastewater treatment device for treatment, and a small amount of trivalent chromium flocculant is added, and the treated water is reclaimed water. Sent to the pool for recycling. Compared with the prior art, the present invention has the characteristics of low cost input, simple operation and control, low disposal cost and complete detoxification.

Description

technical field [0001] The invention relates to a method for harmless disposal of wet chromium slag. Background technique [0002] Chromium slag is a high-risk solid waste, which mainly includes chromium salts, Al 2 o 3 , SiO 2 , MgO, Fe 2 o 3 , CaO, etc., the main pollutants are hexavalent chromium and trivalent chromium, and the chromium residue usually contains 1% to 5% hexavalent chromium. Generally, most trivalent chromium compounds are insoluble in water, non-toxic and harmless, and are essential trace elements for humans and mammals. Usually, the toxicity of chromium slag mainly comes from hexavalent chromium, which is listed as one of the eight most harmful chemical substances to the human body and one of the three carcinogenic metals recognized internationally. Among them, calcium chromate is easy to cause Cancer of the respiratory system, the minimum amount of hexavalent chromium poisoning is 110μg / m 3 . my country stipulates that the maximum allowable conc...

AI Technical Summary

Problems solved by technology

[0006] (1) There are great difficulties in detoxification

[0007] Since chromate is a strong oxidizing agent, the reduction of hexavalent chromium is relatively complete at high temperature, but some low-valent chromium is inevitably oxidized to hexavalent chromium during the cooling process, although it can be engineered through kiln design and operation To control the oxidation of low-valent chromium, but there are relatively high requirements for the control of process conditions and the quality of operators

[0008] (2) High process energy consumption and high pressure on factory health and safety

[0009] The dry disposal process is usually carried out at high temperature. In the process of chromium slag disposal, it is necessary to control the content of chromium-containing dust in the air during the operations of calcination, grinding, transportation, feeding, discharging and storage, so as to achieve the health of the disposal workshop. Safety requirements, so the disposal process needs to be operated under micro-negative pressure conditions, or increase the dust removal in the workshop, these operations will inevitably lead to increased energy consumption in the disposal process

[0010] (3) Large equipment investment and high operating costs

[0017] Among the three harmless disposal technologies mentioned above, the dry method technology is widely used in domestic research and industrialization, but it has the disadvantages of large investment, complicated operation control, high disposal cost, and incomplete detoxification.

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