A PROCESS FOR THE RECOVERY OF NICKEL AND CHROMIUM FROM THE PICKLING BATH SLUDGE OF STAINLESS STEEL.

摘要

This invention relates to a process for the recovery of nickel and chromium from the pickling bath sludge generated during the pickling of the stainless steel. The process comprises treating leach liquor containing sodium chromate and its acidification with HCI, reducing the same with sodium sulphite and then hydrolyzing with NH4OH to precipitate chromium as Cr (OH)3 , which on calcinations yields chromium oxide (Cr2O3). From the chromium free sludge, nickel was recovered as ferro-nickel by carbothermic reduction. The process is useful for the stainless steel and ferro-alloys producing industries. The quantitative recoveries of nickel and chromium is in the range of about 93-95% and 95-96% respectively.