Idaho County free press. [volume] (Grangeville, Idaho Territory) 1886-current, 1890-08-08

phur would be oxidized and lost. The
best that can be done seems to be-: To
place the pyritous ore in that position
where it will be the last portion to be
heated-that is near the bottom of the
charge-and to use coal with caution in
that locality. The extra portion of coal,
for reduction of metal to combine with
the sulphur, should be mixed with the
top portion, only, of the initial charge /:
giving to the lower parts, only a suf-
ficient quantity to reduce the magnetic
oxide which is left by the sulphur; or
about the equivalent of 2.6 per cent, in
pure carbon, of the estimate weight of
such oxide.
Fhe pyrites, II used in this way. would
count for next to nothing as u collect
ing medium, and very large portion of
the matte product would have to be
continually returned to the furnace.
Where low grade mates from other
sources are available, they may, of
course, be used for the filling and for
the top charge. Where pyrites alone
are to be used. and the supply is scanty,
two thirds of the entire output of matte
should be continually crushed and re-
turned; mixing one part with the initial
charge and using the other for the top
ping of after the roasting. 1t is to be
understood, of course, that any increase
in the matte product, from utilization of
sulphur. by any mode of smelling. must
be at the expense of the iron oxide /;
and where pyrite is cheaper than iron
ore, no coal should be used.
Where the supply of pyritous mater
ial is abundant, the same may be crush
ed and mixed in with the initiel charge,
the coal being omitted, or used with
great caution. But this manner of pro-
cedure can only produce, practically, a
quantity of, possibly, not more than
two thirds of the amount of the matte
which may be obtained by the previous
mode from the same quantity of pyrites.
Theoretically, the quantity of matte
would be but one-half as great, were
the liberated sulphur all wasted, as il
would BIZ were it all utilized; but, prac-
tically. anything like perfect realization
of theoretical "ifs"-except in matters
of waste--can not be expected.
In former paper, l, inadvertently,
made mis- .statement of this matter Of
the loss and gain ratio; writing 80 pei
cent" where it should have been loo
per cent of gain, or double the quantity
The loss, reckoning the other way would
be so per cent of the maximum quantity
of matte that might be produced by
utilizing all of the sulphur.
Where the pyrtous material consists
of complex ores, with a little pyrites
scattered among the other minerals, ther
a mixed charge is the best that can be
done. 1t is not easy to determine wit h
out experiment, just how much coal Car
be used without precipitation of metallic
iron from the Stag. At least one hal
of the surplus sulphur of the pyrites will
be set free at comparatively low tenn.
perature, aud it seems certain that, in
the mixed charges, a large part of this
free sulphur must be wasted in the re.
duction of the sesqui oxide of iron tc
the magnetic oxide. With pure magne'
tite for fiux, this difficulty would bt
avoided; but much of the sulphur would
be lost as vapor nevertheless. This por.
ton CD of the surplus sulphur-as sci
free at frst-will, for one part of pyrite
reduce four parts of the sesqui- oxide oil
iron to the magnetic oxide: and as l tc
is greater than the ratio of pyrite to
iron oxide in extreme cases.it will be APP.
parent that this first portion of sulphur
may be entirely used up in such reduc
ton; and that, for this first reduction, q
further quantity of coal may be required
Where the ratio of pyrite to sesqui-ox.
ide, in the charge, is greater than to 4
the sesqui-oxide will, probably, all bt
reduced to the magnetic oxide by thu
sulphur; and then, the permissible pro.
portion of coal may be only SO much al
will bring this oxide to fuxing condition
or the equivalent, in pure carbon, o
$50 per cent of its weight. This much
carbon will, l believe. be permissible il
all possible cases. except where concen.
tration of the matte is desirable; but tn,
conditions of the operation seem so un
certain that | can not attempt to say
how much this percentage of carbon
may be increased. And, as the proper
tons of the ingredients of the charge
are varied. to meet the various qualities
of an available ore supply, the matter o
correct carbon proportioning become.
still more complicated. Any portion o
sulphur which remains to be liberated
after the temperature has been increased
to the degree at which the activity o
the coal, as a reducing agent begins, will
probably, all combine with the iror
which is reduced by the carbon; and
whatever the amount of the sulphdes
so produced, such product will require &
proportionate quantity of coal for the
reduction of It's iron from the Stag com.
pound. Here, again, the appearance o
metallic silver, lead or iron in the matte
product will be the experimental indi.
cation of too much carbon. The carbon
proportion may be Increased until thit
result is reached and may then be di.