Biological leaching-solvent extraction-electrodeposition recovering method for heavy metal copper in sludge

Abstract

The invention relates to a biological leaching, solvent extraction and electrowinning recovery method for heavy metal copper in sludge, and is a method of dissolving the copper from the sludge by biological leaching method, separating and enriching the copper in leaching solution by solvent extraction method, and recovering the metal coppe by electrowinning electroless plating copper technology, and is a harmless and resourceful treatment technology for municipal sludge and industrial sludge with higher copper content. Firstly, the biological acidization which lowers the ph value of a sludge system and oxygenizement of compound acidophilic thiobacillus under aerobic condition in the presence of energy matter are utilized to enable the heavy metal copper in the sludge to abundantly dissolved out from solid phase to liquid phase, so that the sludge can be harmless; secondly, the copper in the biological leaching solution is extracted by using a copper extractant M5640 so that the copper enters an organic phase, and then the copper is conducted back extractioin by using sulfuric acid so that the copper enters the water phase again so as to separate and enrich the copper; finally, the enriched copper solution is electrolyzed to causes the copper to be deposited, and the copper is recovered to be resourceful. The technique not only can remove the heavy metals in the sludge and kill pathogens, but also ensures that the treated sludge is easy to dehydrate and settle and the heavy metal copper dissolved out can be recovered to achieve the purposes of harmlessness, reduction and resource of the sludge.

Description

1. Technical field: [0001] The invention relates to a technology for recovering heavy metal copper in urban sludge, industrial sludge and silt while making the sludge harmless and reducing in volume, and belongs to the technical field of environmental engineering. 2. Technical background: [0002] Sludge from sewage treatment plants contains a large amount of organic matter and plant nutrients such as N and P, but it also enriches a large amount of heavy metals (50% to 80%) in sewage. According to reports, in some urban sewage treatment plants with a large proportion of industrial wastewater (especially from the machinery industry, IT industry and electroplating industry), the urban sewage sludge has a higher content of heavy metals, such as Cu can reach several Thousands or even tens of thousands of mg / kg. At the same time, sludge from some industrial enterprises, such as electroplating sludge, also contains a high amount of Cu. The high amount of heavy metals in sludge w...

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Problems solved by technology

However, unlike metal ore and electroplating sludge, which are dominated by inorganic phases, the above-mentioned sludge contains a high amount of organic matter (30% to 60%). After bioleaching, will a large amount of water-soluble organic matter in the leachate be Affect the selective extraction, separation and purification of copper? Does the separation and enrichment of the copper solution have economic benefits for further electrowinning recovery? Has the recycled sludge achieved the goal of harmlessness? These aspects have not been reported so far

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