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.

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Liberation of Nb/Ta minerals from Cassiterite ore during comminution is difficult. Microwave pre-treatment of cassiterite ore using batch multiple mode microwave was done. The ore was characterized and the effects of various parameters affecting the liberation of Nb/Ta minerals were investigated. It was found that the ore contains 76. 1%wt of SnO2 and traces of Nb2O5 (0.62% wt) and Ta2O5 (0.81% wt). The major phases in the cassiterite ore after pre-treatment were Pyrochlore, Cassiterite, Sillimanite, Ferrotapiolite, Niobium Tantalum, Niobium Titanium, Iron Tin, Niobium Tin, Iron Tantalum and Niobium tin silicide. The ore displayed a significant liberation of the Nb and Ta minerals at 100% irradiation and the high temperature of 540 C was achieved. Significant changes were observed from the SEM/EDS and the Mapping of the distribution of the Nb/Ta minerals showed that there was an improvement in the liberation of these minerals. It is concluded that the use of microwaves brings changes in the matrix pattern of the cassiterite ore, favouring the liberation of microwave susceptible minerals phases.

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