The Foundations of Chemistry

22-4 Refining of Metals 907

TABLE 22-3 Some Specific Reduction Processes

Metal Compound (ore) Reduction Process Comments

mercury HgS (cinnabar) Roast reduction; heating of ore in air

HgSO heat

2 888nHgSO 2

copper sulfides such as Cu 2 S Blowing of oxygen through purified Preliminary ore concentration and
(chalcocite) molten Cu 2 S purification steps required to
Cu heat remove FeS impurities
2 SO 2 888n2CuSO 2

zinc ZnS (sphalerite) Conversion to oxide and reduction with Process also used for the production
carbon of lead from galena, PbS
2ZnS3O heat
2 888n2ZnO2SO 2
ZnOC888nheat ZnCO

iron Fe 2 O 3 (hematite) Reduction with carbon monoxide
produced from coke
2C (coke)O heat
2 888n2CO
Fe heat
2 O 3 3CO888n2Fe3CO 2

titanium TiO 2 (rutile) Conversion of oxide to halide salt and Also used for the reduction of UF 4
reduction with an active metal obtained from UO 2 , pitchblende
TiO heat
2 2Cl 2 2C888nTiCl 4 2CO
TiCl heat
4 2Mg888nTi2MgCl 2

tungsten FeWO 4 (wolframite) Reduction with hydrogen Used also for molybdenum

WO heat

3 3H 2 888nW3H 2 O

aluminum Al 2 O 3
xH 2 O Electrolytic reduction (electrolysis) in
(bauxite) molten cryolite, Na 3 [AlF 6 ], at
1000°C
2Al heat
2 O 3 888n4Al3O 2

sodium NaCl (sea water) Electrolysis of molten chlorides Also for calcium, magnesium, and

2NaCl888nheat 2NaCl other active metals in Groups IA

(^2) and IIA
Impure
solid
Impurities are
concentrated
here
Molten
zone
Heater
Purified
solid
Figure 22-4 A representation of a zone refining apparatus.