Statistical Evaluation and Optimization of Factors Affecting the Leaching Performance of Copper Flotation Waste

Table 8

Estimated regression coefficients for concentration of leached copper.

Term	Coef.	SE Coef.	𝑇	𝑃
Constant	438.141	77.8093	5.631	0.000
pH	−36.180	16.1679	−2.238	0.037
Stirring time	0.538	0.5119	1.052	0.305
Temperature	−9.494	2.4252	−3.915	0.001
pH*pH	2.087	1.1702	1.783	0.090
Stirring time*stirring time	−0.003	0.0020	−1.493	0.151
Temperature*temperature	0.100	0.0263	3.813	0.001
pH*stirring time	0.009	0.0465	0.199	0.844
pH*temperature	0.090	0.1686	0.531	0.601
Stirring time*temperature	0.008	0.0070	1.143	0.267

𝑆 = 28.6208, PRESS = 38892.6, 𝑅-Sq = 72.10%, 𝑅-Sq (pred) = 33.77%, and 𝑅-Sq (adj) = 59.55%.