Tin is an indispensable metal in the modern industry. The current tin
smelting processes, however, have the disadvantages of high smelting
temperature, long smelting time, especially high tin loss ratio (>10 wt%).
The tin loss attributes to the volatilization as gaseous SnO and stannous
silicate (SnO?SiO2) residual in the slag. An innovative approach for
preparing metallic tin effectively from cassiterite in the presence of
Na2CO3, named gas-based reduction roasting followed by water leaching
process, is under development in Central South University, China. The present
study, using chemically pure SnO2 and SiO2, aims to determine the impact of
Na2CO3 on the metallic tin preparation from cassiterite by the novel process
using XRD, SEM-EDS, chemical analysis, etc. It was found that Na2CO3
effectively restrained the tin volatilization as SnO and the formation of
hardly reductive SnO?SiO2 during the reduction roasting process. In the
presence of Na2CO3, most of SnO2 in the raw materials (mixture of SnO2+SiO2)
was directly reduced to metallic tin, and part of SnO2 reacted with Na2CO3 to
form intermediate Na2SnO3, which was then reduced to metallic tin. The SiO2
was transformed into Na2SiO3 and then went into the water solution in the
following water-leaching process. The main reactions of the SnO2 + SiO2
system in the presence of Na2CO3 under reductive atmosphere were ascertained.
Adsorptive Removal of Phosphate Ions Using Leached Sea Nodule Residue Generated by the Reduction–Roasting Ammoniacal Leaching Process
