Effect of Quartz on the Preparation of Sodium Stannate from Cassiterite Concentrates by Soda Roasting Process

Abstract

Sodium stannate (Na2SnO3) has been successfully prepared by a novel process of roasting cassiterite concentrates and sodium carbonate (Na2CO3) under CO–CO2 atmosphere, namely soda roasting-leaching process. However, more than 22 wt. % tin of the cassiterite was not converted into Na2SnO3 and entered the leach residues. Quartz (SiO2) is the predominant gangue in the cassiterite, and phase evolution of SnO2–SiO2–Na2CO3 system roasted under CO–CO2 atmosphere was still uncertain. In this study, the effect of SiO2 in cassiterite concentrates on preparation of Na2SnO3 was clarified. The results indicated that Na8SnSi6O18 was inevitably formed when cassiterite and Na2CO3 were roasted above 775 °C under CO–CO2 atmosphere via the reaction of SnO2 + 6SiO2 + 4Na2CO3 = Na8SnSi6O18 + 4CO2, and formation of Na8SnSi6O18 would be increased with increasing roasting temperature and Si/Sn mole fraction. In addition, it was found that Na8SnSi6O18 was insoluble in the leachate at pH value range of 1–14, which, therefore, was enriched in the leach residues. The silicon content of the cassiterite concentrates should be controlled as lower as possible to obtain a higher conversion ratio of Na2SnO3.

Identification of tin species released in solution during the water leaching of solids from the alkaline smelting (NaOH-KOH) of stanniferous ores

“…The tin leaching yield achieved 95.87%, a value close to fthat reported by Yuma et al (2020) but higher than the ones from previous studies in literature (Bunnakkha et al 2012;Zhang et al, 2019; with the use of higher temperatures. As for other chemical species released in solution, except Fe, the leaching yield was above 50%.…”

“…As for other chemical species released in solution, except Fe, the leaching yield was above 50%. Given that the pH was equal to 11.9, literature (Yuma et al , 2020;Zhang et al, 2019) states that one may find chemical species such as Sn(OH) 6 2− , Sn(OH) 5 − , Si(OH) 6 2− , HSiO 3 − and SiO 3 2− in the aqueous solution from the smelting products leaching, using water as solvent. Fig.…”

Study of Using Quartz Powder as a Mineral Admixture to Produce Magnesium Oxysulfate Cement

“…Filler quartz (Q) has been used to reinforce cementitious materials, e.g., Portland cement, alkali activated slag cement, due to its physical dilution effect and filling effect [29][30][31][32]. For instance, our previous work found granite powders (D 50 ≈ 10 µm) with a Q purity of 70.8 wt.% can increase the compressive strength, chlorion-and sulphatecorrosion resistance of MOS paste through exhibiting its filling effect in the system, improving the pore structure of matrix [6].…”