| 摘要 |
<p>Heat treatment salts are recovered from water used to wash the workpieces after treatment. The water is fed to an evaporator heated to 200-600 degrees C. by the same salt as that employed in the treatment, so water is removed and the salts are dry enough to be recycled into the heat treatment bath. The pref. evapn. temp. is 200-500 degrees C and the steam evolved is condensed and returned, esp. as hot water, to the washing bath. The pref. plant consists of a boiler for heating the salt and a pump feeding the molten salt to the evaporator. The molten salts are used for the heat-treatment or colouring of iron, steel, tool steel, brass or bronze, and the carry over of salt from the molten salt bath to the aq. washing bath is 20-100 g salts/m2 of workpiece surface. This loss is expensive and also causes environmental contamination if the spent washing soln. is fed into the drains.</p> |
