The Art of Talc Flotation for Different Industrial Applications

Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO2 (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries.

Recovery of Cassiterite and Topaz Minerals from an Old Metallurgical Dump, Eastern Desert of Egypt

Huge amounts of tailing dumps as a result of mines’ blasting operations were impacting economic and environmental problems. Evaluation of one of these tailing dumps of the Eastern Desert of Egypt showed the presence of reasonable amount of cassiterite mineral reaching 0.199% SnO2. The mineral cassiterite was found as finely disseminated particulates, reached to 5 microns, within varieties of quartz-feldspar-hornblende-biotite granitic formations. In the present study, the processing regime considered from the beginning the alignment between reaching cassiterite mineral liberation size, and its extreme brittleness character. Stirring ball milling technique was applied to produce −0.51 mm product with minimum fines as possible, which was left aside for a separate study. The ground product −0.51 + 0.074 mm was subjected to joint shaking table/dry high intensity magnetic separation techniques after splitting it into two fractions, −0.51 + 0.21 mm and −0.21 + 0.074 mm. Each fraction was separately subjected to “Wilfley” shaking table. At optimum conditions, a shaking table concentrate was obtained with 0.29% SnO2 and an operational recovery reached 96.94% from a feeding contained 0.19% SnO2. The heavies and the two middling products after shaking table were directed separately after dryness to dry high intensity magnetic separation using “Eriez” rare earth roll separator, meanwhile the light fractions were rejected. Mathematically designed experiments were applied to optimize the separation process. At optimum conditions, a final cassiterite concentrate was obtained with 11.25% SnO2, and an operational recovery 94.08%. In addition, a topaz mineral concentrate was separated at splitter angle 65˚.

Differential Flotation of Some Egyptian Feldspars for Separation of Both Silica and Iron Oxides Contaminants

An anionic-cationic flotation of two Egyptian feldspar samples, representing Road Ashaab locality of the Eastern Desert of Egypt, was investigated on both laboratory and pilot plant scales. The pegmatites belong to the alkali feldspar granite type, mostly microcline and orthoclase, KAL Si3O8 coarse grained rocks. Quartz, as the main gangue mineral, occurs in two forms as either free grains or as veins intercalating the feldspar crystals or, sometimes, intermingled with them. Iron, on the other hand, is found in three different forms as free magnetite embedded in the feldspar crystals, as microcrystalline crystals, or as magnetite filling cracks in the feldspar. Dissolution of magnetite to hematite is, sometimes, observed. Grinding of the feldspar samples to less than 0.25 mm followed by desliming was optimized in the laboratory, using a ball mill in closed circuit with the screen. Anionic flotation of the iron oxide impurity from the -0.25 + 0.03 mm ground product was successfully conducted using locally produced dodecyl benzene sulphonic acid—rice bran oil/kerosene promoter at pH 3. Cationic flotation of feldspar from this product was then carried out employing a locally produced quaternary ammonium salt in presence of HF acid, as a silica depressant and a feldspar activator at pH 3. Feldspar final concentrates assaying 80.8% - 89.5% feldspar mineral, 0.119% - 0.127% Fe2O3 and 16.84% - 18.65% Al2O3, were obtained at the optimum operating conditions that satisfy the requirements of the ceramic industry. Continuous 200 kg/h pilot plant runs were conducted using the appropriate equipment, based upon the laboratory findings to produce feldspar concentrates assaying 16.38% - 18.13% Al2O3, and 0.13% - 0.15% Fe2O3. Materials’ metallurgical balance and complete chemical analyses were shown.