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

Table 9

Estimated regression coefficients for concentration of leached copper (reduced).

Term	Coef.	SE Coef.	𝑇	𝑃
Constant	331.331	44.6537	7.420	0.000
pH	−6.835	2.5007	−2.733	0.011
Stirring time (ST)	0.449	0.1035	4.340	0.000
Temperature (𝑇)	−8.295	2.2282	−3.723	0.001
Temperature*temperature (𝑇^2)	0.100	0.0275	3.637	0.001

𝑆 = 30.0083, PRESS = 33253.1, 𝑅-Sq = 61.66%, 𝑅-Sq (pred) = 43.37%, and 𝑅-Sq (adj) = 55.53%.