Harmless treatment method of red sludge in after-treatment liquid of cold galvanizing

A harmless treatment and post-processing technology, applied in dehydration/drying/concentrated sludge treatment, iron oxide, iron oxide/iron hydroxide, etc., can solve secondary pollution of the environment, waste of resources, inability to be effectively utilized, etc. problems, to achieve the effect of solving secondary pollution, benefiting environmental protection, and reducing production costs

Inactive Publication Date: 2015-10-14
HEBEI JIANZHI CASTING GROUP
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Problems solved by technology

The red mud discarded without harmless treatment not only pollutes the environment twice, but als

Method used

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  • Harmless treatment method of red sludge in after-treatment liquid of cold galvanizing

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Embodiment Construction

[0012] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0013] As shown in the process flow diagram of the present invention, the present invention comprises the following steps:

[0014] A. Drying and dehumidification: Transport the red mud to the shed area and stack it naturally. After drying until it is basically dry mud or slightly wet, it can be filled and sealed. The slightly wet moisture content of the red mud should be controlled at about 17%;

[0015] B. Filling and sealing: choose a high-temperature resistant container, put the air-dried red mud into the container and compact it to minimize the air trapped in the red mud to ensure the quality of the heating treatment, and then cover and seal, that is, put the lid on Use mud or other materials that are resistant to high temperature and not easy to shrink and deform tightly at the joint with the mouth of the high temperature resistant container to ensure the tight...

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Abstract

The invention discloses a harmless treatment method of red sludge in an after-treatment liquid of cold galvanizing, which includes following steps: (a) air-drying and demoisturizing the red sludge to obtain dry red sludge or slight-wet red sludge; (b) filling a container with the dried red sludge, compacting the dried red sludge and sealing the container; (c) heating the container in a high-temperature kiln, increasing the temperature to about 950 DEG C, maintaining the temperature for 8-10 h, and naturally decreasing the temperature for 15-17 h after the fire is extinguished; (d) taking out the container from the kiln and naturally cooling the container to obtain a solid substance formed after heating; (e) performing identification to the solid substance formed after heating the dried red sludge, wherein the solid substance is sheet-like (or piece-like) in appearance, is grey-black in color, is about 0.07 times by the volume of the non-heated dried red sludge and is about 0.22 times by the volume of the the non-heated dried red sludge. The main component of the solid substance is useful ferric oxide [Fe2O3] with a less amount of other harmless substances. The harmless treatment method is simple in processes, can effectively solve a problem of secondary pollution to environment due to the red sludge in the after-treatment liquid of cold galvanizing, is beneficial to environment protection, can increase economic benefit of the cold galvanizing industry and can reduce production cost.

Description

technical field [0001] The invention relates to a method for harmless treatment of industrial waste, in particular to a method for harmless treatment of red mud in post-treatment liquid of cold galvanizing. Background technique [0002] In the production of cold galvanizing, castings cleaned by shot blasting need to be pickled and washed for rust removal, and the waste liquid produced is mainly ferrous chloride [FeCl 2 ] and ferric chloride [FeCI 3 ] and the remaining hydrochloric acid [HCl]. For the needs of environmental protection, these waste liquids need to be post-treated according to the current industry standards, that is, adding sodium hydroxide [NaOH] and a small amount of polyaluminum chloride [PAC], ferrous sulfate [FeSO 4 ], polyacrylamide [PAM], defoamer. Sodium hydroxide is neutralized with waste liquid to form iron trihydroxide [Fe(OH) 3 ] and sodium chloride [NaCl] precipitates, polyaluminum chloride and polyacrylamide adsorb ferric hydroxide, making it ...

Claims

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Application Information

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IPC IPC(8): C02F11/12C22B1/00C01G49/06
Inventor 李友宾尹魁任福艳任劲峰王宝海
Owner HEBEI JIANZHI CASTING GROUP
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