The teller. [volume] (Lewiston, North Idaho) 1876-1878, 1877-05-19
THE WILLARD PROCESS.

to the process of z. A. Willard of Col
orado, for roasting ores so as to save
much larger per cent Of the precious
metals than by other processes. We
give below an account Of the process,
it being extracts from the Denver Tri.
bune:
Mr.. Wizards method is as follows ::
After the ore is crushed in Blake
cru.hor, pulverized in ball pulverzer
and screened to eighty, it is drawn out
on a mixing floor where the first stage
of the process begins. A quantity of
fine carbonaceous material, by prefer
ence sawdust, which is inexpensive and
in finely divided condition, is first
spread upon the floor and thoroughly
w,t with salt water. The ore is spread
evenly over it and carefully rake into
it till the two materials are thoroughly
mixed. The wetting with salt water is
continued until the mass is slightly i'd
hesive when pressed in the hand. 1t is
now ready for charging into the furnace
The furnaces, which are only expert
mental ones, are four feet in diameter,
circular in form. and sixteen inches
deep, with a capacity of seven hundred
pounds. The cover is sheet iron, loosely
fitting, and opening by hinge. On
the back Of the furnace, and under the
cover, is a fue leading to the chimney
for carrying off the gases and vapors.
In the bottom Of the furnace is pipe
about an inch in diameter, connected
with an air compressor for introducing air
and water vap,r. Underneath the fur.
mace is fire box with the usual appl-
ances for heating. The method Of US.
ing the furnace is to build fire 10 the
fre-box and keep the draft open until
the bottom Of the furnace IS about red
hot, when the doors are closed and little
or no fuel is added till the end Of the
treatment. or till the furnace is ready
for fresh charge.
The furnace bens hot enough. a thin
layer Of aw,dust, straw or any c0nven-
lent carbouaceouS material is strewn over
the bottom and the mixed ore is charged
in till it is filed to the Aue. The air
compressor is set in motion, the air ad-
mittcd through suitably arranged valves
into the bottom, aud the action begins
Immediately.
The theory Of what takes place is as
follows: The saw.dust strewn over the
bottom Of the furnace underg'es decon'
position or slow combustion, and com
municates it to the saw.dust in the ere
The sulphuret decomposes BY the heat
and hydro carbon gas and carbnnic OK
ide form with the water sulphurous acid
which attacks tho salt. dec'mposing it
The chlorine freed from the salt com
bines with the iron, cope er, god. silver
and any other metal left exposed by the
decomposition Of the sulphuret, and
forms chlorides Of the metals. These
metals then, except the gold and silver
are changed into oxides by the draft o
hot oxygen from the compressor, which
is constantly forcing its way up iron
below. The silver is not affect ID By
the oxygen, but remains a chloride o
silver. while the gold is rendered br'gA
and free. The gases in passin!
through the mass of wet ore are almos
cold when they issue from the top o
the furnace, and may be condensed in
chamber IL desired. After an hour tn
top Of the mass in the furnace begin
TO undergo combustion, and in less tha'
three hours the whole action ceases, ant
the ore Is roasted.
It is then found that oil the sulphur
1ellnrium, arsenic and antimony hav
disappeared. all the base metals are ox
idss, the gold is perfectly free andt
silver il chloride. Not trace OF de
leterious material is left in the ore
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