Electrochemical machining of metals - in appts. which is also used for inexpensive detoxication of neutral or basic electrolytes or their waste solns.

摘要

After the machining, the electrolyte or soln. contains heavy metal ions, esp. Cr(VI); the machined workpiece is removed, and Fe(II) ions are generated in the machining appts. for redn. of ions in the electrolyte. The pref. reducing agents are Fe(OH)2 and Fe3O4 obtd. by electrochemical dissoln. of an unalloyed steel electrode used instead of the workpiece in a soln. of alkali-chlorides and/or -nitrates; during redn., a protective gas, esp. CO2, N2 or Ar, is pref. used to reduce the effect of O2 in the ambient air on the Fe(II) ions. The consumable steel electrode may be a workpiece with a higher iron content than a high alloy workpiece previously machined in the electrolyte. A substantial saving in detoxication costs can be achieved.