Waste knowledge

New technology for chromic acid recycling

chemical treatments coarsing plastic plating process is one of the key technologies of plastic plating. Chromic acid/sulphuric acid of thick liquid composed of simple, made easy, convenient operation and maintenance, low investment, the effect can satisfy the requirements for metal adhesion strength. However, roughening process of traditional Cr6+ toxic in large consumption of chromic anhydride into "three wastes", air and water pollution, damage to the ecological environment, and harm to human health, but also fail to achieve energy conservation and cleaner production. To do this, you must use new technology for chromate reduction the amount of pollution from the source, a significant reduction in the amount of pollution and recovery chromic anhydride, and advanced recycling and end to realize energy saving and emission reduction, cleaner production, protection of the environment.

traditional chrome anhydride/sulfuric acid plastic rough of process of insufficient: chrome anhydride/sulfuric acid rough of plastic, purpose is can makes plastic surface produced sponge-like micro-holes and hydrophilic can, meet metal coating combined force strength of requirements, but rough of reaction in the only has not to 5% of Cr6+ was plastic decomposition restore into Cr3+,95% above of chrome anhydride with chrome fog, and abandoned rough of liquid and cleaning water loss, into has "waste", serious pollution environment. Crude Cr6+ formed in the liquid can be recycled, practice was wasted.

at present, the commonly used chemical precipitation, chelating agents, heavy metal ion capture agent, chromium removal machines, methods of bio-treatment of wastewater containing Cr6+, 1g chromium chromium is comparable to 3G prices and eventually gets is chromium. Environmental pollution by chromium containing Cr3+. Brick or recovery of chromium from chromium to increase treatment costs. Therefore, the traditional process is the pollution first and treatment later, reduce Cr6+ pollution Cr3+ pollution still inevitable, chromic acid and water resources do not increase their utilization.

cycle economic mode rough of plastic process of features: cycle economic mode rough of plastic process from source Shang cut has chrome anhydride Sources volume, again with recycling parts with out of rough chrome anhydride Crystal solid instead of has traditional recycling rough of liquid; recycling of rough chrome anhydride Crystal and recycling slot liquid in the plastic decomposition product points left, rough chrome anhydride Crystal precipitation for rough of slot cycle using, plastic decomposition product was parts with into cleaning sink in. In view of the greater dilution of principles, the use of four closed water tank cleaning, as the chromic pollution has been cut from the source volume, and the empty tank recovery, thus decreased concentration of chromic acid in the washing tank a lot, with burning of ceramic membrane filter, clean washing tank plastic decomposition products such as organic impurities, first supplementary armoring of the washing bath bath. Environmental protection Cr6+ pollution is not allowed, so restoring trough adding a reducing agent Cr6+ into Cr3+. Counter-current washing and save water resources, using three-stage counter-current washing, filtering wastewater containing Cr3+ removal of suspended debris, using ion-exchange method or membrane replace traditional chemical precipitation method for treatment of waste water (chromium-containing very low concentrations to meet the technical conditions), recycling of Cr3+ and the water cycle. Recycling chromic acid mist and burning of electrolytic oxidation Ceramic tube Cr3+ into Cr6+ and supporting the use of the technology equipment.

China is plastic-coated country, chrome-plated and the consumption of 30% calculations, coarsening 2000 plastic consumption of chromic acid is at least 20000t 15190t,2007 year. New technology for recycling chromic acid recycling 90%, 1 save 18000t, saving tens of billions of tons. Production of 1T of chromic anhydride, 3T chromium slag and chromium fog and waste, while energy consumption. Roughening of the cleaner production of chromic acid recycling of plastics technology at home and abroad first, but cuts of more than 95% from the source pollution of chromic acid, automatic and manual production lines operating for many years shows that implementation is very good.

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