Process for recovering chromium from hexavalent chromium-containing wastewater
Through three-stage countercurrent extraction and two-stage countercurrent back-extraction method, hexavalent chromium is converted into trivalent chromium, and is recycled through organic reducing agent under acidic conditions, which solves the problem of high consumption of chemicals in the extraction process and realizes the production of chromium salts. Efficient recycling and low-cost production reduce the generation of high-salt wastewater.
Active Publication Date: 2015-07-22
HUNAN YONKER ENVIRONMENTAL PROTECTION RES INST
View PDF7 Cites 9 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Problems solved by technology
[0004] The technical problem solved by the present invention is to avoid the large amount of acid and alkali agents in the extraction and stripping process, and reduce the consumption of agents
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreExamples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0015] In the process provided in this example, the chromium-containing wastewater used is the chromium-containing wastewater in the wastewater collection pool of a chromium salt factory, and the hexavalent chromium content is 53 mg / L. The process comprises the following steps: using trialkyl tertiary amine as extractant and kerosene as solvent to prepare a trialkyl tertiary amine-kerosene solution containing 30 wt% of extractant; preparing concentrated sulfuric acid into dilute sulfuric acid with sulfuric acid content of 10 wt% Finally, the pH value of the chromium-containing wastewater is adjusted to 1.0 to 2.0; the prepared 30wt% trialkyl tertiary amine-kerosene solution is added to the chromium-containing wastewater to extract hexavalent chromium. During the extraction, the water phase / oil phase flow rate ratio =15:1 (i.e. equivalent to chromium-containing wastewater being concentrated 15 times), three-stage countercurrent extraction, a sampling port is set at the outlet of...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
Login to View More Abstract
The invention relates to a process for recovering chromium from hexavalent chromium-containing wastewater. The process comprises the following steps: (1) extracting hexavalent chromium in the wastewater to an organic phase by utilizing an extracting agent, and separating hexavalent chromium from a water phase to obtain a hexavalent chromium-loaded organic phase; (2) reducing the hexavalent chromium-loaded organic phase with an aqueous solution of an organic reducing agent, reducing hexavalent chromium into trivalent chromium, reversely extracting trivalent chromium into the water phase, and separating the organic phase from the water phase to obtain a solution of the trivalent chromium and a renewable organic phase, wherein the organic reducing agent is one or a mixture of alcohols, aldehydes and carboxylic acids with the carbon atom number of 1 to 3; (3) evaporating a solvent from the solution of trivalent chromium, catalyzing, and recovering trivalent chromium. According to the process, a high-concentration reserve extracting liquid is obtained by reducing and reversely extracting, so that the chromate production difficulty and the cost during a later period are greatly reduced; the organic reducing agent is selected and used; the final oxidation product is carbon dioxide and water; the chromate is not required to be separated from other salts; relatively pure chromate is easily obtained.
Description
technical field [0001] The invention relates to a process for recovering chromium from waste water containing hexavalent chromium, which belongs to the field of sewage treatment. Background technique [0002] Chromium (Cr 6+ ), will produce a large amount of chromium (Cr 6+ ) waste water. Chromium is one of the highly toxic elements. Direct discharge will cause serious pollution to the environment. Human contact or ingestion will cause serious injuries such as skin ulcers, respiratory inflammation, anemia, and neuritis. It is also one of the known carcinogens. [0003] Currently, chromium (Cr 6+ ) The harmless treatment of wastewater is mainly chemical reduction, sedimentation and sealing up for landfill. If the processed chromium (Cr 3+ ) waste residue is discharged or landfilled, in the long run, it will also cause pollution to the environment. There are also data showing that chromium (Cr 6+ ) waste water, but since the extraction is carried out under the condition...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/10C01G37/00
CPCC02F1/26C02F2101/22C22B34/32Y02P10/20C22B3/20C22B7/006C01G37/08C22B3/32C22B3/262C22B3/282C22B3/306
Owner HUNAN YONKER ENVIRONMENTAL PROTECTION RES INST