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This paper presents the results of a study performed on silica sand samples to determine the effect of operating parameters (collector type and dosage, solids content in the pulp, pulp pH and air flow rate) on the concentrate grade and mass recovery in laboratory-scale column flotation. Through the analysis of variance (ANOVA), it was determined that the pulp pH had a significant impact on all four of the observed grade parameters (mass contents of SiO2, Al2O3, Fe2O3 and TiO2 in the concentrate). Air flow rate had a significant impact on the mass contents of SiO2 and Al2O3. The solids content in the pulp only significantly affected the mass content of Fe2O3. The mass recovery was significantly influenced by the pulp pH, with a high level of significance (p-value (p) = 0.002917), as well as by the air flow rate (p = 0.010285). On the basis of a model of the relationship between the respective grade parameters and tested operating variables, it was determined that with the use of the Aeromine 3030C collector (at a dosage of 500 g/t) the highest-grade concentrate regarding the mass contents of SiO2, Al2O3 and TiO2 was achieved with a pulp pH within a range from 2.4 to 3 and an air flow rate above 26 L/h. The lowest mass content of Fe2O3 in the concentrate was achieved at a pulp pH in a range from 2.2 to 2.8 and a solids content in the pulp between 2.0% and 3.5%. [ABSTRACT FROM AUTHOR]

• Recycling of electrical cables can be improved by using electrostatic separation. • Small grain sizes contain more than 60% of Al. • The Al mass fraction of 97.86% at 91.20% recovery could be obtained. • The splitter position has the most significant influence on separation. • The roll speed and the interaction of splitter and roll speed have an influence. Cables and wires have a widespread use due to their application in electric power and data transmission. Since they consist of a conductive core (Cu or Al) and an insulating layer (polymer), they can be brought back to life after disposal through recycling in the form of secondary raw materials such as copper, aluminium and/or polymer. The aim of this paper is to research the possibilities of electrostatic separation use for separating aluminium left in residue fraction after the process of recycling Al waste electric cables, as well as to determine the influence of operating parameters and the optimal separation conditions. Waste fraction characterisation has determined that aluminium is mainly found in small–size particles (<2 mm) with the mass fraction higher than 60%. During the research planning the central composite design was used and three operating variables of an electrostatic separator were tested: roll speed, voltage and separation splitter position. Results have shown that it is possible to obtain a concentrate with the Al mass fraction of 97.86% at 91.20% recovery. It has been shown that the splitter position has the most significant influence on the grade of concentrate and recovery. It has also been shown that the roll speed individually and the interaction of the roll speed and splitter position have a significant influence on the grade of concentrate. [ABSTRACT FROM AUTHOR]