Eureka weekly sentinel. [volume] (Eureka, Nev.) 1887-1902, 1888-07-14

ter treatment, assays about 40 ounces lie
ton, the results are very good. II il is o
higher value it is brought down by the adj
dition Of more lead. The reason Of this 4
that after certain point is reached. tn,
mechanical affinity Of lead for gold an,
silver Is taxed and losse, are Incurred
Similarly less lead Is used II the resultinc
bullion falls below 40 ounces, care bsins
taken, however, TO keep the percentage d
extraction as good. A crust Of black on
ide of iron two or three inches thick is al
ways found on the speiss after treatment,
the arsenic having been mostly expelled
from that part.
Experiments have been made with hot
air, but the results have not shown a sutH.
cient improvement upon those obtained by
the use Of a cold blast to Justify the cost
involved. The whole operation occupying
such short time, there Is little opportu.
| nifty for chilling; on the contrary the cold
air furnishes oxygen for the promotion of
combustion, thereby increasing the TEN.
| perature.
The time consumed in the operation is
| chiefly dependent upon the condition of
the molten mass II it be thick and pasty,
a longer time is required than il il runs
easily, for it must allow Of thorough in
ternixture with and an easy grayitation OF
the lead. Under normal conditions IT re-
| quires but from two TO three minutes for the
maximum results obtained.
The pot which receives the charge from
the converter is constructed on the plan OF
the commonly used Stag pot, but heavier,
on account OF the greater duty imposed
upon it. The interior Is smeared with
sand or rhyolite, which is sufficiently re-
fractory 20 protect the pot from the cor
rosive action Of the molten mass during
the time Of exposure.
At the bottom is a half-inch hole for
tapping the lead. After reaching the pot
the speiss chills very quickly, but not be-
fore the lead has gravitated to the bottom,
carrying with IL the silver and gold. The
lead is preserved in a molten condition by
the heat still retained in the speiss. and
when the latter has solidifed the lead is
tapped into molds, and afterwards desil-
verified BY the Parkes zinc process.
The speiss is dumped and the pots are
again smeared with sand, the heat re-
tanned by the pot suficing TO dry it. The
results vary with the degree Of efficiency
with which the work is carried on, but, un-
like any other process, are tolerably con-
slant.
The following figures will bear direct tes-
timony Of the efficiency Of the process.
from two convertels;
700tons Of speiss ehargei
in the Raschette fur ozs.
mace, produced $40 SILVER. GOLD.
tons containing ...... .7O6S o5l SIC, ,2i1.ss
The lead bullion OBJ
tAined by the process
contained. ..-......-..... - 5sss OJ b,i44 70
Lass.........................ii64-O2 OF d, ,Os7 50
Percentages of fexiraction silver 50 so gold se'2s
The loss OF lead in the operation is small,
varying from 8 To 8 per cent
A number Of interesting facts may lie
noted in connection with the reduction by
this process. The speiss is fed in large
Jumps, making it most practical to use
coke as a fuel on account Of the coarseness
Of the charge. This is direct saving in
Eureka, the cost OF smelling with charcoal
being greater than with coke. Again, in
this connection, the arsenic in the course of
reduction burns to Asa Os producing heat,
and thus acting as saver of fuel.
Being basic In its nature, the speiss facil-
itates the reduction Of silicious ores, which
Is the general character of the ores Of this
district. Being easily fusible and working
so rapidly, il increases the capacity Of the
furnace over what it would be were the
ore used alone
On comparing this with the process em.
ployed at the Richmond, it will be seen
that hot molten lead is superior to cold
lead or litharge in this function, since the
latter chills the speiss. The difference in
results is chiefly due to this fact. Lead
has greater affinity for arsenic when
melted by the heat Of the speiss than
when added in a molten state, thereby ne
cessitating more calcination preparatory to
desilverization. 1t has been found that
lead added in the cold state takes up 10
per cent arsenic while melting with it,
whereas lead previously melted absorbs
but ) per cent, making difference of from
two TO three days in the time required to
eliminate it,
Regarding Mr.. Bryan's use of air. to
eliminate the arsenic from the speiss, it is
not feasible. Nothing practical has yet
been found that will withstand the cor
rosiye action of molten speiss under air
pressure long enough for even meager
showing.
The labor of two men for every eight
hour shift at wages of SO per shift is re.
quired, aud only fuel enough is necessary
to keep the lead needed for treatment in
molten state.
The process has proven an admirable sue
cess, and has been the means OF material
izing the hidden treasures of an enormous
accumulation Of material heretofore re-
garded as a waste product.