The Impact of the Imperial Smelting Furnace on Non-ferrous Metallurgy

IN 1936 at the Avonmouth Works of the National Smelting Company in England, zinc was produced by both the Hori-zontal Process and by the Vertical Retort Process, then recently installed under licence from the New Jersey
Zinc Company.
In the Research Department we were not satisfied
with either process. The Horizontal Process was inter-mittent in operation, and was a heavy consumer of
fuel. In addition, the vast number of small retorts
which were used, required a considerable amount of
labour, and the work was hot and arduous. The Vertical
Retort Process represented a considerable improvement,
in that it was continuous in operation, and the consi-derably fewer retorts required much less labour and
the thermal efficiency was higher. It was still essen-tially a small unit operation however, maintenance
costs were high, and to make good briquettes, a coal
of special quality was required, which was in limited supply.