Method of treating stainless steel passivating cleaning wastewater by employing calcium carbide waste residue

Abstract

The invention discloses a method of treating stainless steel passivating cleaning wastewater by employing calcium carbide waste residue. The method comprises the following steps of: transferring stainless steel passivating cleaning wastewater into a neutralizing tank for alkali adjustment, then transferring the wastewater to a clarification pond, and adding cationic polyacrylamide to generate a metal hydroxide precipitate to obtain clarified waste liquor; mixing a calcium carbide waste residue suspension liquid; transferring the separated clarified waste liquor to a fluoridation pond, adding a hydrochloric acid solution, then adding the calcium carbide waste residue suspension liquid and polymeric aluminum and feeding the mixed liquid into a settling pond, wherein fluorine ions and calcium ions are combined to generate a CaF2 precipitate to be removed; and feeding the wastewater without the CaF2 precipitate into the final neutralization tank, adding a neutralizing liquid into the final neutralization tank to obtain treated waste liquor, and then discharging the waste liquor by means of a sand filter. The method disclosed by the invention uses the calcium carbide waste residue to replace lime for treating the stainless steel passivating cleaning wastewater, has the advantages of low cost and convenient in use, plays a role of treating waste with waste, and is remarkably in environmental benefit and economic benefit.

Description

technical field [0001] The invention relates to the field of wastewater treatment, in particular to a method for treating stainless steel passivation cleaning wastewater by using calcium carbide waste residue. Background technique [0002] Stainless steel has excellent mechanical and chemical properties such as corrosion resistance, heat resistance, mechanical strength, wear resistance, formability, compatibility, etc., and it has a beautiful appearance and light weight. It is used in petroleum, chemical, machinery, shipbuilding, Widely used in nuclear power, military industry, construction and other industries. In the production process of stainless steel, it has to go through annealing, normalizing, quenching, welding and other processing processes, and a thin and dense oxide film will be formed on the surface. Its main components contain a large amount of chromium oxide and nickel oxide, which will affect the appearance of the product. Therefore, it must be removed by su...

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Problems solved by technology

However, a large amount of lime is used in the wastewater treatment process of this patent. Although the price of lime is cheap, its solubility is low, so it can only be added as emulsion, and the lime particles are relatively thick, and the neutralization reaction speed is slow, which is easy to cause the center of lime particles The part did not participate in the reaction and increased the amount of lime, and at the same time the CaF produced by the reaction of fluoride ions and calcium ions 2 It will be wrapped on the surface of calcium hydroxide particles, and it will not be fully utilized. Therefore, it is necessary to increase the dosage of lime milk during operation, so that even when the pH value of the wastewater reaches 12, the fluoride ion concentration can only be reduced to 15mg. / L or so, this one increases the cost, and the other increases the amount of sludge deposition

[0006] Therefore, combined with the advantages of large amount of calcium carbide residue and high calcium content, in view of the slow reaction rate, low utilization rate of limestone and large amount of by-products in the process of limestone treatment of stainless steel passivation cleaning wastewater, it is necessary to provide a solution for the wastewater treatment process. Methods of environmental pollution and product efficiency issues to effectively solve the secondary reuse of solid waste

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