When mineral processing separation results, for either constant or varying quality of the feed, can be approximated on the so-called Fuerstenau upgrading plots with the same one-fitting parameter a, then this parameter can be used as a selectivity indicator. If the equation has a form [...], where [...] stands for recovery of non-useful component in tailing while\ksi is the recovery of useful component in the concentrate, then at the same selectivity of upgrading (constant a) the increase of the useful component in the feed \alfa results in an increased amount of this component in both concentrate \beta and tailing [...] while the ratio of [...] to \beta is linearly dependent on \alfa when \epsilon is constant. Thus, at a constant selectivity a and constant \epsilon an increase in \alfa leads to a greater increase of the considered component in the tailing \theta than in the concentrate \beta.

Investigations of n-dodecane used in flotation of copper ore from the Legnica-Glogow Copper Basin (LGOM) were presented in the paper. The aim of the work was estimation of influence of nonpolar reagent's on the results of copper ore flotation. Two series of flotation tests were conducted. The first series - flotation experiments with standard flotation with xanthate collector only (KEtX), were compared with the second series: flotation experiments with n-dodecane addition (C12) in the first stage and then xanthate addition (KEtX). n-dodecane was used in form of aqueous emulsion and frother was aqueous solution of \alfa-terpincol. Flotation results showed that a part of copper minerals float with n-dodecane, and the rest of them is recovered using xanthate collector. The best results were obtained for the first series (with xanthate only). These flotation results were compared with the results of copper sulphide ores flotation with n-heptane addition. It was found that with the doses reagent used, n-heptane has a higher selectivity in comparison with n-dodecane. In the presence of various doses of n-heptane, tested material enriched better in organic carbon carriers than in the copper minerals.