Improvement of Egyptian Talc Quality for Industrial Uses by Flotation Process and Leaching

Abstract

Talc is an industrial mineral that is widely used. It is always associated with other minerals, which determine the quality of talc samples for industrial purposes. Various operating variables control the natural floatability of talc. For enhancement of talc flotation, sodium hexametphosphate is used as a depressant for associated gangue minerals. In addition, oleic acid (in an equal mixture with kerosene) is used as an anionic collector. The results presented in this paper provided useful and important information on how to improve the quality of talc for industrial uses. The optimum conditions were obtained at pH = 11, depressant dosage = 1.0 kg/t, collector dosage = 1.2 kg/t and pulp density = 200 g/L. At these conditions, SiO 2 assay increased from 54.10% to 54.94%, MgO assay increased from 29.90% to 31.76%, CaO decreased from 0.80% to 0.42%, Al 2 O 3 decreased from 5.50% to 3.11%, Fe 2 O 3 decreased from 8.20% to 7.24%, the whiteness increased from 75.4% to 83.7%, and the loss on ignition decreased from 6.64% to 5.21%. The mass recovery of final concentrate was 92.4%. The component recoveries of SiO 2 and MgO (the major constituents of talc) in the final concentrate were 93.8% and 98.2%, respectively. More improvement of talc quality was obtained by leaching of final concentrate of flotation with 10% dilute hydrochloric acid. The mass recovery of final product was about 85% of initial feed. In this final product, Fe 2 O 3 decreased to 3.12%, CaO decreased to 0.38%, and Al 2 O 3 decreased to 3.01%. The assay of SiO 2 increased to 58.96%, MgO percent was nearly the same, the whiteness increased to 88.5%, and the loss on ignition decreased to 4.03%. The final product is suitable for many industrial uses such as low-loss electronics (a type of ceramics), paints, rubber, plastics, roofing, textiles, refractories, insecticides and coating of welding rods.

Purification and Removal of Hematite from Talc by Acid Leaching Assisted by Chlorination Techniques

“…In a typical dry chlorination experiment, 5 g of talc sample was mixed thoroughly with 5 g of NH 4 Cl, and the mixture was transferred into a 100-mL crucible. The crucible was then placed in a muffle furnace and heated to 250 °C for 120 min.…”

“…The mainstream gangue minerals in talc are magnesite (MgCO 3 ), carbonates, dolomite (CaMg(CO 3 ) 2 ), calcite (CaCO 3 ), serpentine, and chlorite (Mg 5 (Al,Fe)(Al, Si) 4 O 10 (OH) 8 ). The gangue minerals being hydrophilic in nature adversely affect the talc ore quality and hinder its industrial utilization [4,5]. For instance, the occurrence of iron oxide both on the surface and entrenched inside talc refutes its ingrained properties and limits its exploitation as an industrial precursor material.…”

“…To date, various techniques have been developed for the purification of talc ores such as floatation, magnetic separation, wet attrition, acid leaching, and chlorination [4,[7][8][9].…”

“…In flotation, talc usually hydrophobic is concentrated at the top as froth, while the gangue minerals are collected at the bottom as tailings, using air bubbles and flotation reagents such as frothers and depressants [10]. However, the final concentrate often contains impurities that need further processing such as magnetic separation and acid leaching [4,11]. Ahmad et al used flotation for the up-gradation of Egyptian talc for industrial applications; however, it was not possible to extract iron and aluminum potentially.…”

Integrated Process for Purification of Low Grade Talc Ores

“…However, this technique applied on talc containing a considerable amount of associated minerals, is not possible for the same reasons explained above. Also, it is not directly applicable to industrial processes because of its high cost (Feng and Aldrich, 2004;Jaramillo et al, 2005;Perez-Maqueda et al, 2005;Ahmed et al, 2007). Jaramillo et al (2005) have reported that acid leaching was more effective than froth flotation to remove iron oxides from talc, mainly by dissolution.…”