Evaluation of the Effect of Residual Silver in Copper on the Cementation Process by Factorial Design and Multiple Regression Analysis

Residual silver in cementator copper was studied to examine its effect on the efficiency of cementation process in form of reduced silver by considering reaction duration, silver content and rotation speed of copper electrodes. The experiments were conducted at room temperature with 100 mm² non-rotating and rotating disc copper electrodes (0 and 500 rpm) alloyed with different Ag ratios (0.5 and 10 %). The reactions were carried out in nitrate solutions in certain reaction time (10 min. and 2 h). Experimental parameters and their levels were determined by precursor tests. The amounts of reduced silver (mg) were expressed as process output. Experiments were designed by full factorial design (2^k) method and analyzed using ANOVA and multiple regression analysis. The maximum amount of reduced silver was obtained at a silver content of 0.5 % with non-rotating disc copper electrode in 2 h reaction duration. The effective parameters on the cementation process were determined as reaction duration, reaction duration and rotation speed of copper electrode and silver content of copper electrode. Correlation coefficients (R² and R² _Adj) were calculated as 0.978 and 0.948, respectively.