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% SiO2, 0.143% Fe2O3, 1.52% Al2O3, and 0.088% TiO2; Fe2O3 had to be reduced to below 0.04%. The reverse flotation tests were carried out with and without indirect ultrasound irradiation. The lowest Fe2O3 grade of the flotation yield was 0.058% and this was achieved using 2000 g/t of C4 collector with 15 min conditioning at neutral pH. C4 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% SiO2, 0.034% Fe2O3, 0.90% Al2O3 and 0.051% TiO2.
Highlights
Silica is an important product in industrial minerals and it has many applications
In order to demonstrate the effect of indirect ultrasound irradiation on the performance of reverse flotation, eight pairs of experiments were selected and the most important responses were investigated
The silica product of flotation tests was dried treated in two stages of dry high intensity magnetic separation
Summary
Silica is an important product in industrial minerals and it has many applications. Silica with low iron content is much in demand for glass, ceramics, and pottery use [1]. Different silica deposits are used in the production of a high purity silica product and they can be classified as three main types [1]: Quartz veins: These deposits are extremely high-grade containing white silica crystals. Quartzite: This is metamorphosed sandstone made up of quartz sand united by siliceous cement, forming low-porosity rock. Quartzite varies from white to gray in color and sometimes brown, red, or yellow due to the presence of small amounts of impurities. Some quartzite deposits may contain up to 99% SiO2
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