(1) No preliminary crushing is required.
(2) The product is largely in the form of lumps, and hence
immediately suitable for blast-furnace work.
(3) The plant and appliances required are simple.
The two methods employed are—(A) open-air roasting, (B) roasting in
kilns.
A. _Open-air Roasting of Lump Ores._—This method is conducted in
heaps or stalls, and the features just considered apply particularly
to this branch of roasting practice. The modern tendency is to avoid
heap-roasting altogether, and it is only conducted when the conditions
are exceptional.