The Neihart herald. [volume] (Neihart, Mont.) 1890-1901, 1892-02-05
MATTE-SMELTING.

Matte-SlneltlnS Ior the eNtract'oii
of gold and silver from their ores is
of German origin, but by the ingen-
uity of few American metalurgists,
it has been so changed from the pre-
vious foreign practice that we can
safely claim it as an American pro-
cess: Its principal distinction is
that it is preeminently suited for the
treatment of base ores, particularly
sulphuretted varities, and generally
speaking, all such ores as are or
were classified as ''refractory" or
s'rebellious," which are so easily
treated by mating that those once
used words have now lost their force
and application. Nothing is too diff
ficult for matte-smelting, and such
substances as sulphur, antimony, ar
senic, etc, which give great trouble
in other modes of treatment, are not
only of no detriment in mating, but
are actually, to some extent, of
great use therein. The valuable
metals which can he extracted by
matte-smelting are gold, silver, plat
mum, copper, nickle, cobalt and,
less perfectly, lead. A large num-
ber of the so-called ''rare" metals
also come down. The percentage
saved is rarely less than so, and
usually somewhat more. The saw
ing of gold is the most perfect, and
in carefully conducted work, is prob
ably equal to the assay valuations.
WE FORM TWO SUBSTANCES IN MAT
the Stag and the matte. The latter
contains the valuable metals united
in homogeneous mass of specific
gravity of the above five, with sui
rhur and with more or less iron,
lead, etc, according to the compo-
sition of the ore. The Stag contains
silico united with various oxides of
the ore, or flux, principally oxide of
iron or manganese, lime, magnesia,
baryta, ETC., none of which do we
desire to save. The proportion of
matte to Stag to secure economical re-
suits should be from one-tenth to one
fortieth, according to circumstances.
1t is in maintaining the proper ratio
between them that the greatest skill
and judgement are deuiauted, for
it can easily be understood that if
the proportion of matte is too large,
it will be poor in valuable metals
and while the extraction may be ex'
cellent the matte will not pay SC
we'll for it's subsequent treatment at
the refinery. But on the other hand
if the amount of matte be small, say
one -fortieth of the ore smelted, il
will stand many reasonable subse.
quent charges for shipping to the
refinery and the commercial success
of the operations will be great. Those
who have an inkling of smelling viii
understand at once that the amount
of sulphur in the smelling charge
governs the amount of matte formed
in the furnace. Experience in leat
smelling applies equally here ane
we may also apply the rules for the
formation of the slags practised ii
the latter art, only that a much large
variety of slags are permissible il
matte, than in lead smelling. Thus
for instance, the bi-silicate slags
found Objectionable in the latte,
;. give excellent results in mating
and for certain classes of ores ar
indispensable. In lead smelling, a
is we'll understood, the silica content
of slags vary, as rule, from 26 t
= 40 per cent, while in mating W
! often make slags as high as SO pc
cent silica, and even more acid one
have been used to advantage. Thi
is an overwhelming advantage i
case of silicous ores.
! Almost every mine produces sui
phur in the form of sulphides, an
some from iron, or substances whic
take it's place, and silica is almos
the universal accompaniment of gol
and silver ores. A custom smelte
= in South Dakota treats quartz carry
ing less than $50 per ton in gol
and silver, purchasing quantity
I. iron pyrites to form the matte an
makes it pay although the limestor
aux necessary to Stag SO much silie
actually weighs more than the or
Tn th;c ooco +ho malta contains HI