Effect of Na2Co3 on the preparation of metallic tin from cassiterite roasted under strong reductive atmosphere

Abstract

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.

Nickel, copper and cobalt coalescence in copper cliff converter slag

“…Vale's Copper Cliff operation extracts nickel from a combination of pentlandite ((Fe,Ni) 9 S 8 ) and variable amounts of chalcopyrite (CuFeS 2 ), pyrrhotite (Fe 7 S 8 ) and/or pyrite (FeS 2 ) and violarite (Ni 2 FeS 4 ) [3][4][5]. Similarly to other pyrometallurgical extraction processes [6], it is technically difficult to produce high-grade nickel concentrate without loss of nickel due to the intergrowth of the various sulphide minerals and the presence of dissolved nickel in the pyrrhotite crystal lattice. Therefore, a bulk concentrate of about 20 wt% CuNiCo is treated in two stages; flash smelting and converting [7][8].…”

The Recovery of Metallic Tin from an Industrial Tin-Bearing By-Product Containing Na2SO4 by Reduction Smelting Process

“…Another factor could be the volatile behavior of SnO at high temperatures. According to Zhang et al [18], in the tin smelting process, more than 5 wt% of tin was volatilized into The effect of Na 2 O/SiO 2 on the recovery of tin was studied in the range of 0.3-0.7 at 1200 • C and 2 h. In this study, the behavior of tin with Na 2 O/SiO 2 was characterized by reduction and volatilization in the process of reduction smelting. In the reduction behavior, Figure 4 shows that tin content in slag strongly depends on Na 2 O/SiO 2 ratio.…”

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

“…Our previous studies have discussed in detail about the formation mechanism of Na 2 SnO 3 ; however, the reaction principle and thermodynamic data of Na 2 CO 3 -SnO 2 -SiO 2 system were unclear [25][26][27]. Hence, the major objectives of this study were: (1) to determine the effect of SiO 2 on the leaching efficiency of Sn and Si; (2) to investigate the effect of SiO 2 on phase evolution of SnO 2 -Na 2 CO 3 system; (3) to ascertain leaching characteristics of the tin, silicon-containing compounds.…”