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Pyrometallurgical Metal Refining of Tin Metal from the Egyptian…
Pyrometallurgical Metal Refining of Tin Metal from the Egyptian Cassiterite Concentrate
Procedure of Refining Process: Purification of Crude Tin Metal Method
Boiling Process
• In the boiling process, the tin was melted in the crucible at 300°C, then agitated with poles of green wood.
• The green wood should be moistening to produce steam along with the mechanical stirring of the poles.
• Most of the remaining impurities are floated on the surface to form scum, which were then removed and tin metal was poured into the steel mould.
Liquation process
• Based on the difference in melting points and the difference in specific gravity of tin alloy components, the liquation refining was carried out.
• In Liquation process, the produced metal from boiling step was put on perforated funnel which was put on a crucible and then placed on the furnace adjusted at 231°C.
• The melted tin runs down and was collected in the crucible, while the other materials remain above as solids. The high purity tin metal was then poured into the steel mould.
Steps for Smelting
Each
run
was carried out
on batches
containing 50 gm of the concentrate, in addition to
**char coal: reductant
sodium carbonate and sodium nitrate: fluxing agents**
The required weight of reactants to desired proportions were
weighed and mixed thoroughly in fireclay scorifiers
and finally the charge was
transferred
to a fixed volume
fireclay crucible
A Muffle Furnace of maximum temperature 1200°C was preheated to the required temperature (850 - 1000°C), then the crucible was inserted into the furnace.
After
completing the reduction reaction
for each run, the
crucible
was
removed
and tin metal was
poured into steel mould
and the slag was collected.
The extracted tin metal and recovered slag were then weighed and analyzed, then continued by
refining process
.
Influences
Smelting temperature has noticeable effect on the reaction rate. An activation energy of 106 KJ/mol was calculated for the reduction of cassiterite concentrate.
The purity of refined tin will be higher. From this case, after boiling process, the purity of refined tin was (99.4 %) and that of Liquation process was (99.6 %).
Basic (alkaline) fluxes gives better recovery, high purity tin metal by using lower smelting temperature and time.
Purpose
• To get pure metal by removing impurities
• To improve the properties of engineering metals and alloy
• Chemical reactivity
• Boiling points
• Hardness
• Thermal and electrical properties
• Mechanical strength
• Resistance
• Ductility
• Specific gravity
Lim Ling Xin
134318
Material Engineering