228 TRANSACTIONS OF THE 
parison’ of their results, is the fact that both were able to 
volatilize a high percentage of the metal contents from 
their ores, and that both concluded their experiments 
facing the same principal difficulty, of being unable satis- 
factorily to collect the metallic fumes from the gases. 
COTTRELL ELECTROSTATIC PRECIPITATOR. 
It was about 1912 when Dr. F. G. Cottrell successfully 
developed the electrostatic principle of separating solid 
constituents from gaseous bodies‘. 
The use of the precipitator as a fume condensor, 
found a ready application in connection with the chloride 
volatilization process. 
METALLURGY OF THE CHLORIDE VOLATILIZATION 
PROCESS. 
PREPARATION OF THE ORE CHARGE. 
The ore is first crushed to a size depending on the 
physical occurrence of the metal-bearing minerals in the 
ore gangue, usually .046 inch or 14 mesh is sufficient. 
The ore with part or all of the chloridizing reagent 
or reagents, usually sodium and calcium chloride, are 
thoroughly mixed and admitted to the furnace for the 
chloridizing roast. 
CHLORIDIZING ROAST. 
The roast is usually conducted at a temperature 
ranging from 850 to 1000° C. Most experiments have 
been conducted in a rotary furnace similar to the cement 
kiln type. The ore charge is continuously fed into the 
furnace at one end and the roasted product discharged 
out of the opposite end. The ore charge in the kiln 
becomes heated as it approaches the discharge and heated 
end of the furnace. Asa result there is a chemical reac- 
5Mining Magazine, March, 1914, vol. 10, p. 200. 
6U. S. Patent No. 1,016,476, issued Feb. 6, 1912. U.S. Patent 
No. 1,035,422, issued August 13, 1912. 
