Abstract
This thesis details results obtained from the smelting process of Cassiterite ore bearing Nb/Ta
minerals. The Cassiterite ore, sourced from the Kibara belt in the Democratic Republic of
Congo (DRC) was characterised using different analytical equipment such as XRF, XRD and
SEM/EDS. It was then treated using a shaking table in order to concentrate it. The Cassiterite
ore was then smelt in a tube furnace and the effect of basicity and smelting time was
investigated.
The chemical and mineralogical studies by XRF and XRD revealed that the Cassiterite ore
sample contained Sn (76.01%), Nb2O5 (0.62%) and Ta2O5 (0.81%). It was mainly composed of
Cassiterite (SnO2) as the major mineral phase with minor compounds of Sillimanite (Al2SiO5),
Ferrotapiolite (Fe(Nb,Ta)2O6), Pyrochlore ((Na, Ca, U)2 (Nb,Ta)2 06) and Tapiolite minerals
(FeTa2O6). These results were confirmed using SEM/EDX. It was further revealed that rich Nb
and Ta minerals (Pyrochlore and/or Tapiolite and/or Ferrotapiolite) are trapped in sizes ranging
from 1.98 to 3.43 μm in the Cassiterite mineral.
The results from the gravity pre-concentration process using a shaking table revealed that the
Sn grade improved from 76.01 up to 90.50%. However, the Sn recovery was 49.6%; 55.5%;
65.69% and 14.8% for sizes of x>212; 212<x<150; 150<x<106 and x<106 μm respectively.
Nb recovery was 48.9%; 34.1%; 49.9% and 10.02% for sizes of x>212; 212<x<150;
150<x<106 and x<106 μm respectively and for Ta 44.4%; 59.3%; 84.69% and 20.9% for sizes
of x>212; 212<x<150; 150<x<106 and x<106 μm respectively. These recoveries are very low
and the Cassiterite ore was smelt without pre-concentration.
Initially, dolomite was used as a fluxing agent in the smelting process without any reducing
agent and smelting at 14000C. The results revealed that after smelting, the chemical
composition of the metal fraction was 95.07 % Sn and 4.92 % Fe and that of slag was 3.67 %
Nb2O5, 4.08 % Ta2O5 and a small amount of SnO2 (1.14%). This shows that there was a need
to add a reducing agent in order to reduce the Fe % present in the metal product.
The sample was then smelt in the presence of different amounts of CaO and MgO in order to
monitor the basicity while blowing CO gas at 14000C. The results show that a metal with Sn
grade of 99% at a recovery of 92% was produced at a basicity of 1.2. The slag analysis revealed...
M.Tech. (Extraction Metallurgy)