UTAH ACADEMY OF SCIENCES 151 
Of interest in blast furnace practice is the use of 
pulverized coal as a fuel. Such use has, during the past 
two years, been brought to actual commercial experi- 
mentation both in Canada and the United States (*) and 
the experiments have been most promising. The pulver- 
ized coal is introduced into the furnace through the 
tuyeres thus decreasing the quantity of coke which it 
is necessary to add to the charge. Results indicate that 
a considerable saving in cost of operation can be effected. 
Having direct bearing on the utilization of pulverized 
coal in blast furnaces is the problem of smelting lead 
and copper ores with high zinc content. In the past, 
the smelting of ores high in zinc in the blast furnace 
has offered considerable difficulty due to. liability to 
freezing of the furnaces with continued operation on 
such ores. Its direct result has been to exclude lead 
and copper ores heavy in zine by a penalty on the zinc 
content. Hall has concluded (*) after extensive experi- 
mentation that the difficulty is due not to the high vis- 
cosity of zinc slag as is popularly supposed but to the 
condensation on the coke of zinc oxide brought up from 
the smelting zone in the charge which renders the coke 
much more difficult of combustion so that proper heat 
is not developed later on in the smelting zone. The use of 
powdered coal may bring about the solution of this 
old problem. 
Another phase of present smelting practice which 
has in the past few years received much attention, due 
in no small part to external pressure brought to bear 
by surrounding communities, is the treatment of flue 
gases. Such gases carry, besides the ordinary products 
of combustion, mechanically carried dust, volatalized 
metallic compounds, and sulphur dioxide gas. Large 
installations of bag houses and Cottrell electrostatic 
precipitators have been made to remove the solid mater- 
ial which is retreated to recover the values contained. 
As a result quantities of arsenic, so necessary in insecti- 
cides, and cadmium are being recovered from material 
which previously was belched forth in smoke clouds 
sBull. Can. Mining Inst. No. 87, p-737, (1919). 
*Hall, Min. and Sci. Press, 1919, Vol. 119, p-699. 
