Ask A Scientist Chemistry Archive

 
name Sam M.
status student
age 12

Question - How would you extract zinc out of zincblende?
-----------------
Sam,

The following zinc extraction process is taken from an Inorganic Chemistry 
Book (London) dated 1939, but the core of the process (Chemistry) is still 
used today.  The zincblende ore is first roasted, and the sulphur dioxide 
produced from the blende may be utilized in the manufacture of sulphuric 
acid.  External heating has to be applied, the blende being raked in a 
series of muffle furnaces through which air circulates.  Care must be 
taken so that only the oxide of zinc is produced:  2ZnS + 3O2  = 2ZnO + 
2SO2.  Some sulfate is always formed and is decomposed at the high 
temperatures used.  The roasted ore is next mixed with half its weight of 
powdered coal and charged into fireclay retort furnaces.  Zinc distills 
off:  ZnO + C = Zn +CO.  The reduction begins at 800 degrees and increases 
rapidly with the rise in temperature.  I hope that this helps.

Sincerely,

Bob Trach
=====================================================