AbstractsChemistry

"Zinc ores containing large amounts of ferric oxide, calamine and willemite have been known for a long time among practical zinc metallurgists to be more difficult to reduce than ores of the same type but free from the above named compounds. This has been thought to be due to the high temperatures necessary for the reduction of the zinc ferrite and the zinc silicates by carbon. The ferrite is formed both during the roasting of sulphide ores and during distillation in the retorts, while calamine and willemite are introduced as such in the ores. The amount of ferrite formed during the roasting process depends almost entirely upon the temperature at which the roast is conducted, as excessively high temperatures are conducive to the formation of the ferrite. The object of the investigation described in this thesis was to determine the effect of various factors on the rate of reduction of zinc ferrite, willemite, and calamine, in order to obtain more specific data concerning the reasons for the difficulty of reducing ores containing large amounts of these compounds" – Introduction, p. 1-2.