Mining Institute, Cola Science Center, Russian Academy of Sciences, Apatity, Russia:

V. A. Ivanova, Leading Researcher, Candidate of Engineering Sciences, gera@goi.kolasc.net.ru
G. V. Mitrofanova, Leading Researcher, Candidate of Engineering Sciences

The accomplished research focuses on separation of calcium-bearing minerals, such as apatite, calcite and dolomite, having similar flotation properties. The indicated set of minerals is typical of baddeleyite–apatite–magnetite ore of the Kovdor deposit, with nonmagnetic fraction represented by apatite–carbonate–silicate ore variety. The optimal compositions and application methods are found for the hydroxyethylated compounds (isononyl phenols and aliphatic alcohols) as modifying agents for the selective flotation of apatite, enabling higher technical-and-economic indices and enhanced ecological safety of apatite concentrate production from Kovdor ore. The influence of hydroxyethylated alkyl phenols (Neonol AF-n) with the hydroxyethylation degree in the range of n = 2–10 on the selective flotation of apatite from different composition samples of apatite–carbonate–silicate ore with Р₂О₅ content of 8.7 and 10.2 % and with the carbonate content magnitude of 1.06–2.16 is investigated. It is shown that modifying agents with 4–10 oxyethyl groups allow production of concentrates with Р₂О₅ content of 37.33–39.62 %. The method is proposed and commercially tested for the separate feed of modifying agents with different hydroxyethylation degrees to the process of flotation. By the test results, given the flotation feed contains 9.5–10.5 % of Р₂О₅ and has the carbonate content magnitude of 1.2–1.6, the separate feed increases Р₂О₅ recovery in the equal-quality concentrate (37 % Р₂О₅) by 2.6 % on the average, at the decreased consumption of modifying agents by 10–25 %. The applicability of alkyl phenol ethoxylates with 3 and 4 oxyethyl groups as mono-regulators instead of a modifying agent with factory composition, at the similar performance is illustrated. The properties of alkyl phenol ethoxylates with 3 and 4 oxyethyl groups are studied. The larger scale tests accomplished on a facility with capacity of 250 kg/h demonstrated applicability of hydroxyethylated (С₁₂-С₁₄) alcohol with 4 oxyethyl groups as a mono-regulator instead of a factory mixture of modifying agents at the same performance. The higher biodegradability of hydroxyethylated alcohols determines their future introduction.

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