The use of acetic acid in the presence of hydrogen peroxide as an alternative agen to cyanidation in silver leaching

In this thesis, the solubility of spherical-granular silver grains sold in the market with a purity of 99.99% in a mixture of acetic acid and hydrogen peroxide under various conditions was investigated. Experiments were carried out in 0.5 L solution in 1 L volume beakers in a hot water bath that can be adjusted to various temperatures. In the studies, the effects of stirring speed, temperature, hydrogen peroxide and acetic acid concentration on the dissolution of granular silver were investigated. According to the results obtained, it was determined that the stirring speed had a negative effect, and as the hydrogen peroxide (0.5-2 M) and acetic acid (0.25-1.0 M) concentrations increased, the silver dissolution rates for certain concentrations increased relatively. With the increase in temperature (40-61.5 °C), the dissolution rate increased, but after a critical temperature of 61.5 °C, the dissolution rate was negatively affected because the hydrogen peroxide decomposition increased. Using the kinetic evaluation, it was determined that silver was compatible with the "shrinking core model" in the acetic acid medium under the effect of hydrogen peroxide and was expressed as "1-(1-X)1/3=kct". The activation energy of 28.80 kJ/mol was calculated for the temperature range of 40-61.5 °C. Keywords: Silver, Hydrogen peroxide, Acetic acid, Cyanidation, Silver acetate.