Empress Catherine II Saint Petersburg Mining University (Saint Petersburg, Russia)

Aleksandrova T. N., Doctor of Technical Sciences, Professor, Head of the Mineral Processing Department, Aleksandrova_TN@pers.spmi.ru
Lushina E. A., Post-Graduate Student, Mineral Processing Department, s235070@stud.spmi.ru
Romashev A. O., Candidate of Technical Sciences, Associate Professor, Mineral Processing Department, Romashev_AO@pers.spmi.ru
Nikolaeva N. V., Candidate of Technical Sciences, Associate Professor, Mineral Processing Department, Nikolaeva_NV@pers.spmi.ru

The use of recycled water in mineral processing plant water supply systems is accompanied by the accumulation of inorganic ions capable of significantly altering the physicochemical properties of flotation reagents and disrupting the stability of the separation process. The aim of this study is to evaluate the effect of the ionic composition of mixed salt systems NaCl – CaCl₂ on the thermodynamic and kinetic characteristics of the methyl isobutyl carbinol (MIBC) foam layer, as well as on the flotation recovery of copper from sulfide ore. NaCl and CaCl₂ solutions at concentrations of 5, 15, and 30 mM with varying ratios (25 : 75, 50 : 50, 75 : 25) were used as research objects; flotation tests were conducted at pH 9 using potassium butyl xanthate as collector and MIBC at dosages of 5–15 g/t. Statistical processing of results was performed using full factorial experiment design and analysis of variance (ANOVA). It was shown that the presence of salts in solution reduces the critical micelle concentration of MIBC and leads to a nonlinear decrease in surface tension, with the maximum reduction in σ and favorable foam formation kinetics achieved at the equimolar NaCl : CaCl₂ ratio. An integral criterion D_f based on Harrington’s desirability function was proposed, allowing simultaneous consideration of thermodynamic and kinetic foam characteristics. It was established that the increase in copper recovery correlates with the reduction in time to reach maximum foam height. During flotation of sulfide ore in a three-phase system, the presence of the solid phase alters the foam layer stabilization mechanisms; however, the proposed methodology is applicable for evaluating various classes of surfactants and will enable identification of the optimal frother depending on the specific ionic composition of recycled water.
This work was supported by the Russian Science Foundation grant No. 26-17-00226.

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