The role of protective alkalinity and Ca²⁺ ions in the cyanidation of refractory silver ores

The effect of protective alkali on the extraction of silver from refractory ores, taken from the Kütahya-Gümüşköy region of Turkey, and the behaviour of dissolved Ca²⁺ ions during cyanidation were investigated. It was shown that high concentrations of protective alkali are beneficial in the cyanidation of these ores, in contrast to gold cyanidation where they prohibit gold dissolution. Calcium ions are advantageous in the cyanidation of sulphidic silver ores since they prevent the detrimental effects of ions which hinder silver dissolution and consume CN^- ions. Using high concentrations of protective alkalis decreases the cyanide consumption.