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Abstract:Removal of iron impurities in silica is one of the most important issues in the glass industry. The most noted impurities are surface coating and staining on silica particles; additionally, some cases of inclusions are observed. The prepared silica sample, for this research work, mostly was in the size range of 106-425 µm. Mineralogical studies indicated the existence of goethite, hematite, limonite and pyrite as the major iron impurities. The poor liberation degree of silica particles from clays encouraged the use of ultrasound irradiation to improve the efficiency of reverse flotation. The head sample contained 96.98% SiO 2 , 0.143% Fe 2 O 3 , 1.52% Al 2 O 3 , and 0.088% TiO 2 ; Fe 2 O 3 had to be reduced to below 0.04%. The reverse flotation tests were carried out with and without indirect ultrasound irradiation. The lowest Fe 2 O 3 grade of the flotation yield was 0.058% and this was achieved using 2000 g/t of C 4 collector with 15 min conditioning at neutral pH. C 4 consisted of Aero 801, Aero 825, oleic acid and sodium oleate at equal dosage. As a result, a flowsheet was developed to include indirect ultrasound irradiation with reverse flotation and two stages of dry high intensity magnetic separation. In conclusion, the best product contained 98.43% SiO 2 , 0.034% Fe 2 O 3 , 0.90% Al 2 O 3 and 0.051% TiO 2 .

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