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Chemical surface treatment of metals in closed circuit - using evaporator to recover water and chemicals from rinsing tanks
Chemical surface treatment of metals in closed circuit - using evaporator to recover water and chemicals from rinsing tanks
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机译:封闭回路中金属的化学表面处理-使用蒸发器从冲洗水箱中回收水和化学物质
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摘要
Metal objects are subjected to chemical surface treatment (I) by spraying or immersion, followed by multi-stage rinsing in which the rinsing water flows in counter-current to the objects. In the novelty, the water from the first rinse is fed to an evaporator, from which the vapour flows via a condenser to the final rinse as pure water, whereas the overflow from the evaporator leads to treatment (I). Chemicals and water corresp. only with the net usage are fed continuously or at intervals to the process. Water from the first rinse may be fed to treatment (I), the latter feeding the evaporator; or the water from the first rinse may be fed to the evaporator and the overflow from the latter fed to a reservoir to which chemicals and water are added and the soln. then fed to treatment (I). The pref. plant consists of a closed circuit including an evaporator and condenser, the evaporator being connected in any of the three ways listed above. Recovery of chemicals and water is obtd., so there use is minimal; no decontamination plant is needed to treat effluents. The process can be used for chromate treatment of Mg objects.
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