Effect of CaO/MgO Ratio on the Product Quality during Tin Smelting

Abstract

The existing tin smelting processes have the disadvantages of high smelting temperature, long smelting time and especially high tin losses. In this paper, the effect of basicity on the product quality during tin smelting was studied by monitoring the CaO/MgO ratio. It was found that the iron content in the metal product depends on the Fe/Sn ratio in the slag. A high tin metal product (98.52% Sn and 1.02% Fe) was obtained and a small loss of Sn went into the slag (<10%) at a reduction temperature of 1400 0 C and basicity of 1.2. The low Fe content in the Sn metal would make the subsequent tin refining easier. The Nb and Ta content in the slag increased to 4.96 and 5.06% respectively. The main phases in the slag were Ferrocolumbite, Niobium oxide and Tantalum oxide. The recovery was high for Sn in the metal and Nb/Ta in the slag.

Review on key parameters during carbothermic reduction of Tin from cassiterite

“…The phases that form in the slag to preferentially collected Nb an Ta are similar when CaO and MgO are kept constant. However, the basicity increase leads to an increase in Sn recovery [8,9]. The change of basicity through the addition of Quartz has a significant effect during the reduction of cassiterite.…”

“…Tantalum oxide and Niobium oxide may reach 5% in the slag while the purity of metal reached a maximum of 99% of Sn and 1% Fe. This makes the slag of considerable value [9].…”