Method for treating trivalent-chromium chromium-plating wastewater

A treatment method and technology for trivalent chromium, which are applied in the fields of metallurgical wastewater treatment, multi-stage water treatment, water/sewage treatment, etc., can solve problems such as difficulty in reaching the standard of trivalent chromium, achieve good market application prospects, low treatment costs, and reduce The effect of COD

Active Publication Date: 2020-02-21
GUANGZHOU ULTRA UNION CHEM LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Based on this, it is necessary to provide a treatment method for trivalent chromium-plating wastewater, so that the complexing agent and trivalent chromium in the treated trivalent chromium-plating wastewater can be effectively treated, and the problem of trivalent chromium in the existing treatment technology can be solved. Difficulty in meeting chromium standards

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  • Method for treating trivalent-chromium chromium-plating wastewater

Examples

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Embodiment 1

[0047] Embodiment 1: process the trivalent chromium plating wastewater containing citric acid

[0048] This embodiment provides a treatment method for trivalent chromium chrome-plating wastewater in a sulfate system, to process trivalent chromium chromium-plating wastewater containing 300 mg / L of trivalent chromium ions and 400 mg / L of citric acid. Organic additive; comprising the steps of:

[0049] Step 1, add ferrous chloride

[0050] The trivalent chromium-plating wastewater is imported from the wastewater regulating tank to the feeding tank, and under mechanical stirring, 15L ferrous chloride solution is added to every ton of wastewater.

[0051] Step 2, precipitation of citric acid and trivalent chromium

[0052] The wastewater flows from the feeding tank into the sedimentation tank. Under mechanical stirring, lime emulsion is added to make the pH of the wastewater to 10-12. Ferrous ions and calcium ions form precipitates with citric acid, and trivalent chromium ions re...

Embodiment 2

[0063] Embodiment 2: process the trivalent chromium plating wastewater containing malic acid

[0064] This embodiment provides a treatment method for trivalent chromium chromium plating wastewater in a sulfate system, to process trivalent chromium chromium plating wastewater containing 100 mg / L of trivalent chromium ions and 800 mg / L of malic acid. Organic additive; comprising the steps of:

[0065] Step 1, add ferrous chloride

[0066] The trivalent chromium-plating wastewater is imported from the wastewater regulating tank to the feeding tank, and under mechanical stirring, 25L ferrous chloride solution is added to every ton of wastewater.

[0067] Step 2, precipitation of malic acid and trivalent chromium

[0068] The wastewater flows from the feeding tank into the sedimentation tank, and under mechanical stirring, lime emulsion is added to make the pH of the wastewater to 10-12, ferrous ions and calcium ions form precipitates with malic acid, and trivalent chromium ions ...

Embodiment 3

[0079] Embodiment 3: process the trivalent chromium plating waste water containing formic acid

[0080] This embodiment provides a treatment method for trivalent chromium plating wastewater in a chloride system to treat trivalent chromium chromium plating wastewater containing 400 mg / L of trivalent chromium ions and 600 mg / L of formic acid. The wastewater contains a small amount of surfactants additive; comprising the following steps:

[0081] Step 1, add ferrous chloride

[0082] The trivalent chromium-plating wastewater regulating tank is input into the feeding tank, and under mechanical stirring, 20L ferrous chloride solution is added in every ton of wastewater.

[0083] Step 2, precipitation of formic acid and trivalent chromium

[0084] The wastewater flows from the feeding tank into the sedimentation tank, and under mechanical stirring, lime emulsion is added to make the pH of the wastewater to 10-12, ferrous ions and calcium ions form precipitates with formic acid, an...

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Abstract

The invention provides a method for treating trivalent-chromium chromium-plating wastewater. Through a synergistic effect of ferrous ions and calcium ions, an organic acid coordination agent containing carboxyl groups in wastewater is precipitated by using ferrous ions and calcium ions, and trivalent chromium released from a complex generates chromium hydroxide precipitates, so that the trivalentchromium is effectively removed. In addition, a sodium hypochlorite solution is used as an oxidant to control the oxidation-reduction potential (ORP) value and the oxidation time, so that an oxidationreaction process is ensured, organic additives in the wastewater can be effectively destroyed, the chemical oxygen demand (COD) of the wastewater is reduced. Indexes meet the wastewater discharge standard, and wastewater treatment cost is reduced and the economic benefit is improved while the environment is protected.

Description

technical field [0001] The invention belongs to the technical field of industrial wastewater treatment, in particular to a treatment method for trivalent chromium plating wastewater. Background technique [0002] Replacing highly toxic hexavalent chromium plating with trivalent chromium plating has been widely used and achieved good environmental and social benefits. [0003] Trivalent chromium plating has been put into large-scale production for a short period of time, and the treatment of its wastewater still needs further research. Trivalent chromium plating includes two systems of sulfate trivalent chromium plating and chloride trivalent chromium plating. In the sulfate system, carboxyl-containing organic acids such as citric acid or malic acid are used as complexing agents. In the chloride system, generally Using formic acid as complexing agent. [0004] Citric acid has strong oxidation resistance, and the efficiency of destroying citric acid by traditional oxidation ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F103/16C02F101/22
CPCC02F1/001C02F1/5245C02F1/56C02F1/66C02F1/76C02F9/00C02F2101/22C02F2103/16C02F2301/08
Inventor 郭崇武黎小阳赖奂汶
Owner GUANGZHOU ULTRA UNION CHEM LTD
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