EXTRACTION OF GOLD AND SILVER BY CYANIDATION PROCESS FROM COMPLEX ORE OF SHOUGHUR AREA CHITRAL, KYBER PAKHTUNKHWA

Abstract

The aim of the research work was to optimize the cyanidation leaching parameters for maximum extraction of gold and silver from complex ore of Shoughur area of district Chitral, Khyber Pakhtunkhwa on laboratory scale testing. The research work was carried out into two parts. In first part the cyanidation parameters like grinding time, dosage of pH, cyanidation time, dosage of sodium cyanide (NaCN) and dosage of lime Ca (OH)2 were optimized. The samples were subjected to differential grinding time varying from 20 to 35 minutes, pH of slurry adjusted from 9 to 11 by adding Ca (OH)2 from 0.5 to 1.5 gm/kg , dosage of NaCN varies from 0.1% to 0.02 % and cyanidation time varies from 0 to 40 hours. The maximum yielded of 71.82 gm/ton of gold grade and silver grade of 34.34 gm/ton was obtained at grinding time of 25 minutes, particle size 63 um, pH 10.40, cyanidation time of 37 hours and at lime dosage of 0.5gm/kg. In the second part the cyanidation process was applied on roasted and un-roasted ore samples. The cyanidation time and grinding time were optimized. The maximum grade of gold 71.82 ppm and silver 25.95 ppm was extracted from roasted ore samples at cyanidation time of 35 hours and grinding time of 30 minutes as compared to unroasted ore samples. It is concluded that cyanidation process on roasted ore samples gives encouraged results as compared to un-roasted ore samples