SMELTING WORKS AND REFINERIES
THE NEW SMELTER AT EL PASO, TEXAS
(April 19, 1902)
In July, 1901, the El Paso, Texas, plant of the Consolidated Kansas
City Smelting and Refining Company[52] was almost completely destroyed
by fire. The power plant, blast-furnace building and blast furnaces
were entirely destroyed, and portions of the other buildings were badly
damaged. The flames were hardly extinguished before steps were taken to
construct a new, modern and enlarged plant on the ruins of the old one,
and on April 15, 1902, nine months after the destruction of the former
plant, the new furnaces were blown in. In rebuilding it was decided to
locate the new power-house at some distance from the other buildings.
The furnaces have all been enlarged, each of the new lead furnaces (of
which there are seven) having about 200 tons daily capacity. These and
the three large copper furnaces have been located in a new position
in order to secure a larger building territory. The entire plant is
modern and up to date in every particular. One of the interesting
features is the substitution of crude oil as fuel in the boiler and
roasting departments. It is intended to use Beaumont petroleum for
the generation of power and the roasting of the ores instead of wood,
coal or coke, and it is expected that a considerable economy will be
effected by this means.
_Power Plant._—The power plant is complete in all respects. It is a
duplicate plant in every sense of the word, so that it will never be
necessary to shut the works down on account of the failure of any one
piece of machinery. There are seven boilers, having a total of 1250
h.p. The four blowers are unusually large, having a capacity of 30,000
cu. ft. of free air per minute. They are direct-connected to three
tandem compound condensing Corliss engines. No belts are used in this
plant, except for driving a small blower of 10,000 cu. ft. capacity,
which will act as a regulator. A large central electric plant has been
installed in the power-house, consisting of two direct-connected,
direct-current generators, mounted on the shafts of two cross-compound
condensing Nordberg-Corliss engines. The current from these generators
is transmitted through the plant, operating sampling works, briquetting
machinery, pumps, hoists, motors, cars, etc., displacing all the
small steam engines and steam pumps used in the old plant. The power
plant is provided with two systems for condensing; one being a large
Wheeler surface condenser, the other a Worthington central-elevated jet
condenser, the idea being to use the surface condenser during a short
period of the year when the water is so bad that it cannot be used in
the boilers. During the remainder of the year the jet condenser is in
service and the surface condenser can be cleaned. The condensed steam
from the surface condenser, with the necessary additional water, goes
back directly to the boilers when the surface condenser is in use. The
power-house is absolutely fireproof throughout, being of steel and
brick with iron and cement floors. It is provided with a traveling
crane, and no expense has been spared to make this, as all other
parts of the plant, complete in every respect. The main conductors
from the generators pass out through a tunnel into a brick and steel
lightning-arrester house, from which point the various distributing
lines go to different parts of the plant.
_Blast Furnaces._—There are seven large lead furnaces, each having a
capacity of 200 to 250 tons of charge per day, and three large copper
furnaces, each having a capacity of 250 to 300 tons per day. All of
the furnaces are enclosed in one steel fireproof building, the lead
furnaces being at one end and the copper furnaces at the other. Each
of the furnaces has its independent flue system and stack. An entirely
new system of feeding these furnaces has been devised, consisting of
a 6 ton charge car operated by means of a street railroad motor and
controller with third-rail system. The charge cars collect their charge
at the ore beds, lime-rock and coke storage, and are run on to 15 ton
hydraulic elevators. They are then elevated 38 ft. to the top of the
furnaces, traveling over them to the charging doors, through which the
loads are dumped directly into the furnaces. This system permits of two
men handling about 1000 tons per day. The same system and cars are used
for charging the copper furnaces, except that, as these furnaces are
much lower than the lead furnaces, the charge is dropped into a large
hopper, from which it is fed to the copper furnaces by a man on the
copper furnace feed-floor level.
NEW PLANT OF THE AMERICAN SMELTING AND REFINING COMPANY AT MURRAY, UTAH
BY WALTER RENTON INGALLS
(June 28, 1902)
Murray is a few miles south of Salt Lake City, with which it is
connected by a trolley line. The new works are situated within a few
hundred yards of the terminus of the latter and in close juxtaposition
to the old Germania plant, which is the only one of the Salt Lake
lead-smelting works in operation at present. The new plant is of
special interest inasmuch as it is the latest construction for
silver-lead smelting in the United States, and may be considered as
embodying the best experience in that industry, the designers having
had access to the results attained at almost all of the previous
installations. It will be perceived, however, that there has been no
radical departure in the methods, and the novelties are rather in
details than in the general scheme.
The new works are built on level ground; there has been no attempt to
seek or utilize a sloping or a terraced surface, save immediately in
front of the blast furnaces, where there is a drop of several feet
from the furnace-house floor to the slag-yard level, affording room
for the large matte settling-boxes to stand under the slag spouts.
A lower terrace beyond the slag yard furnishes convenient dumping
ground. Otherwise the elevations required in the works are secured by
mechanical lifts, the ore, fluxes and coal being brought in almost
entirely by means of inclines and trestles.
The plant consists essentially of two parts, the roasting department
and the smelting department. The former comprises a crushing mill
and two furnace-houses, one equipped with Brückner furnaces and the
other with hand-raked reverberatories. The reverberatories are of
the standard design, but are noteworthy for the excellence of their
construction. Similar praise may be, indeed, extended to almost all
the other parts of the works, in which obviously no expense has been
spared on false grounds of economy. The roasting furnaces stand in a
long steel house; they are set at right angles to the longer axis of
the building, in the usual manner. At their feed end they communicate
with a large dust-settling flue, which leads to the main chimney of
the works. The ore is brought in on a tramway over the furnaces and is
charged into the furnaces through hoppers. The furnaces have roasting
hearths only. The fire-boxes are arranged with step-grates and closed
ash-pits, being fed through hoppers at the end of the furnace. The
coal is dumped close at hand from the railway cars, which are switched
in on a trestle parallel with the side of the building, which side is
not closed in. This, together with a large opening in the roof for
the whole length of the building, affords good light and ventilation.
The floor of the house is concrete. The roasted ore is dropped into
cars, which run on a sunken tramway passing under the furnaces. At the
end of this tramway there is an incline up which the cars are drawn
and afterward dumped into brick bins. From the latter it is spouted
into standard-gage railway cars, by which it is taken to the smelting
department. The roasted ore from the Brückner furnaces is handled in a
similar manner. The delivery of the coal and ore to the Brückners and
the general installation of the latter are analogous to the methods
employed in connection with the reverberatories.
The central feature of the smelting department is the blast-furnace
house, which comprises eight furnaces, each 48 by 160 in. at the
tuyeres. In their general design they are similar to those at the
Arkansas Valley works at Leadville. There are 10 tuyeres per side, a
tuyere passing through the middle of each jacket, the latter being
of cast iron and 16 in. in width; their length is 6 ft., which is
rather extraordinary. The furnaces are very high and are arranged for
mechanical charging, a rectangular brick down-take leading to the dust
chamber, which extends behind the furnace-house. The furnace-house is
erected entirely of steel, the upper floor being iron plates laid on
steel I-beams, while the upper terrace of the lower floor is also laid
with iron plates. As previously remarked, the lower floor drops down a
step in front of the furnaces, but there is an extension on each side
of every furnace, which affords the necessary access to the tap-hole.
The hight of the latter above the lower terrace leaves room for the
large matte settling-boxes, and the matte tapped from the latter runs
into pots on the ground level, dispensing with the inconvenient pits
that are to be seen at some of the older works. The construction of
the blast furnaces, which were built by the Denver Engineering Works
Company, is admirable in all respects. The eight furnaces stand in a
row, about 30 ft. apart, center to center. The main air and water pipes
are strung along behind the furnaces. The slag from the matte-settling
boxes overflows into single-bowl Nesmith pots, which are to be handled
by means of small locomotives. The foul slag is returned by means of a
continuous pan-conveyor to a brick-lined, cylindrical steel tank behind
the furnace-house, whence it is drawn off through chutes, as required
for recharging.
The charges are made up on the ground level, immediately behind the
furnace-house. The ore and flux are brought in on trestles, whence the
ore is unloaded into beds and the flux into elevated bins. These are
all in the open, there being only two small sheds where the charges are
made up and dumped into the cars which go to the furnaces. There are
two inclines to the latter. At the top of the inclines the cars are
landed on a transferring carriage by which they can be moved to any
furnace of the series.
The dust-flue extending behind the furnace-house is arranged to
discharge into cars on a tramway in the cut below the ground level.
This flue, which is of brick, connects with the main flues leading to
the chimney. The main flues are built of concrete, laid on a steel
frame in the usual manner, and are very large. For a certain distance
they are installed in triplicate; then they make a turn approximately
at right angles and two flues continue to the chimney. At the proper
points there are large dampers of steel plate, pivoted vertically, for
the purpose of cutting out such section of flue as it may be desired to
clean. Each flue has openings, ordinarily closed by steel doors, which
give access to the interior. The flues are simple tunnels, without
drift-walls or any other interruption than the arched passages which
extend transversely through them at certain places. The chimney is of
brick, circular in section, 20 ft. in diameter and 225 ft. high. This
is the only chimney of the works save those of the boiler-house.
The boiler-house is equipped with eight internally fired corrugated
fire-box boilers. They are arranged in two rows, face to face.
Between the rows there is an overhead coal bin, from which the coal is
drawn directly to the hoppers of the American stokers, with which the
boilers are provided. Adjoining the boiler-house is the engine-house;
the latter is a brick building, very commodious, light and airy. It
contains two cross-compound, horizontal Allis-Chalmers (Dickson)
blowing engines for the blast furnaces, and two direct-connected
electrical generating sets for the development of the power required
in various parts of the works. A traveling crane, built by the Whiting
Foundry Equipment Company, spans the engine-house. In close proximity
to the engine-house there is a well-equipped machine shop. Other
important buildings are the sampling mill and the flue-dust briquetting
mill.
A noteworthy feature of the new plant is the concrete paving, laid on a
bed of broken slag, which is used liberally about the ore-yard and in
other places where tramming is to be done. The roasting-furnace houses
are floored with the same material, which not only gives an admirably
smooth surface, but also is durable. The whole plant is well laid out
with service tramways and standard-gage spur tracks; the intention has
been, obviously, to save manual labor as much as possible.
THE MURRAY SMELTER, UTAH[53]
BY O. PUFAHL
(May 26, 1906)
This plant has been in operation since June, 1902. It gives employment
to 800 men. The monthly production consists of about 4000 tons of
work-lead and 700 tons of lead-copper matte (12 per cent. lead, 45 per
cent. copper). The work-lead is sent to the refinery at Omaha; the
matte to Pueblo, Colo. Most of the ores come from Utah; but in addition
some richer lead ores are obtained from Idaho, and some gold-bearing
ores from Nevada.
For sampling the Vezin apparatus is used, cutting out one-fifth in
each of three passes, crushing intervening, the sample from the third
machine being 1/625 of the original ore; after further comminution of
sample in a coffee-mill grinder, it is cut down further by hand, using
a riffle. The final sample is bucked down to pass an 80-mesh sieve, but
gold ores are put through a 120-mesh.
The steps in the smelting process are as follows: Roasting the poorer
ores in reverberatory furnaces and in Brückner cylinders. Smelting
raw and roasted ores, mixed, in water-jacketed blast furnaces,
for work-lead and lead-copper matte, the latter containing 15 per
cent. lead and 10 to 12 per cent. copper. Roasting the ground
matte, containing 22 per cent. of sulphur, down to ¾ per cent. in
reverberatory furnaces. Smelting the roasted matte together with acid
flux in the blast furnace for a matte with 45 per cent. copper and 12
per cent. lead.
Only the pyritic ores are roasted in Brückner furnaces, the lead ores
and matte being roasted in reverberatory furnaces. Each of the 20
Brückner furnaces, which constitute one battery, roasts 8 to 12 tons
of ore in 24 hours down to 5½ to 6 per cent. sulphur, with a coal
consumption of two tons. The charge weighs 24 tons. The furnaces make
one turn in 40 minutes. To increase the draft and the output, steam
at 40 lb. pressure is blown in through a pipe; this has, however,
resulted in increasing the quantity of flue dust to 10 to 15 per cent.
of the ore charged. Ten furnaces are attended by one workman with one
assistant, working in eight-hour shifts. For firing and withdrawing the
charge five men are required.
The gases from the Brückners and reverberatory furnaces pass into a
dust-flue 14 × 14 ft. in section and 600 ft. long, built of brickwork,
with concrete vault; in the stack (225 ft. high, 20 ft. diameter) they
unite with the shaft-furnace gases, the temperature of which is only 60
deg.
There are 12 reverberatory furnaces with hearths 60 ft. long and 16
ft. broad. They roast 14 tons of ore (or 13 tons of matte) in 24 hours
down to 3½ to 4 per cent. sulphur, consuming 32 to 34 per cent. of coal
figured on the weight of the charge. There are 12 working doors on each
side. The small coal (from Rock Springs, Wyoming), which is burnt on
flat grates, contains 5 per cent. ash and 3 to 5 per cent. moisture.
The roasted product is dumped through an opening in the hearth,
ordinarily kept closed with an iron plate, into cars which are raised
by electricity on a self-acting inclined plane. Their content is then
tipped over into a chute and cooled by sprinkling with water. From here
the roasted matte is conveyed to the blast furnace in 30-ton cars. The
roasted ore is tipped into the ore-bins.
There are eight blast furnaces, 48 × 160 in. at the tuyeres, of which
there are 10 on each of the long sides. The hight from the tuyeres to
the gas outlet is 20 ft., thence to the throat 6 ft.; the distance
of the tuyeres from the floor is 4 ft. The base is water-cooled. The
water-jackets of the furnace are 6 ft. high. The tuyeres (4 in.)
are provided with the Eilers automatic arrangement for preventing
the furnace gases entering the blast pipes. The blast pressure is
34 oz. The furnaces are furnished with the Arents lead wells; the
crucible holds about 30 tons of lead. The slag and the matte run into
a brick-lined forehearth (8 × 3 ft., 4 ft. deep), from which the slag
flows into pots holding 30 cu. ft., while the matte is tapped off into
flat round pans mounted on wheels.
The charge is conveyed to the feed-floor by electricity. The furnace
charge is 8000 lb. and 12 per cent. coke, with 30 per cent, (figured on
the weight of the charge) of “shells” (slag). Occasionally as much as
230 tons of the (moist) charge, exclusive of coke and slag, has been
handled by one furnace in 24 hours. During one month (September, 1904)
40,000 tons of charge were worked up, corresponding to a daily average
of 166 tons per furnace.
The lead in the charge runs from 13 to 14 per cent. on an average. The
limestone, which is added as flux, is quarried not far from the works.
The coke used is in part a very ordinary quality from Utah; in part a
better quality from the East, with 9 to 10 per cent. ash. The matte
amounts to 10 per cent. The slag contains 0.6 to 0.7 per cent. lead and
0.1 to 0.15 per cent. copper. The slag has approximately the following
composition: 36 per cent. silica, 23 per cent. iron (corresponding to
29.57 per cent. FeO), 23 per cent. lime, 3.8 per cent. zinc and 4 per
cent. alumina.
The work-lead is transferred while liquid from the furnaces to kettles
of 30 tons capacity, in which it is skimmed, and thence cast in molds
through a Steitz siphon. First, however, a 5.5 lb. sample is taken
out by means of a special ladle, and is cast into a plate. From this
samples of 0.5 a.t. are punched out at four points for the assay of the
precious metals.
For the purpose of precipitating the flue dust, the blast-furnace gases
are passed into brickwork chambers in which a plentiful deposition of
the heavier particles takes place. From here the gases go through an L
pipe of sheet iron, 18 ft. in diameter, to the Monier flues, which have
a cross-section of 256 sq. ft. and a total length of 2000 ft. A small
part of the flues is also built of brick. The gases unite with the hot
roaster gases just before entering the 225 ft. chimney. In the portion
of the blast-furnace dust first precipitated the silver runs 22 oz. per
ton, while that recovered nearer the stack contains only 8 oz. The flue
dust is briquetted with a small proportion of lime, and, after drying,
is returned to the blast furnaces.
THE PUEBLO LEAD SMELTERS[54]
BY O. PUFAHL
(May 12, 1906)
At the Pueblo plant, ores containing over 10 per cent. lead are not
roasted, but are added raw to the charge. For such material as requires
roasting there are in use five Brückner furnaces. The charge is 24 tons
for 48 to 60 hours; the furnaces make one revolution per minute and
roast the ore down to 6 per cent. sulphur. There are also two O’Harra
furnaces, each roasting 25 tons daily, and 10 reverberatory furnaces 75
ft. in length, each roasting 15 tons of ore daily down to 4 per cent.
sulphur.
The charge for smelting is prepared from roasted ore, together with
Idaho lead ore, Cripple Creek gold ore, briquetted flue dust, slag
and limestone. There are seven water-jacketed furnaces, which smelt,
each, 150 tons of charge per day. The furnaces have 18 tuyeres, blast
pressure 34 oz., cross-section at the tuyeres 48 × 148 in. They are
charged mechanically by a car of 4 tons’ capacity.
The output of lead is 11 to 15 tons per furnace. The matte, which
is produced in small quantity, contains 8 to 12 per cent. lead and
the same percentage of copper. It is crushed by rolls, roasted in
reverberatory furnaces, and smelted with ores rich in silica. The matte
resulting at this stage, running 45 to 50 per cent. in copper, is
shipped to be further worked up for blister copper.
The work-lead is purified by remelting in iron kettles, the cupriferous
dross being pressed dry in a Howard press, and sent to the blast
furnaces. The work-lead is sent to the refineries at Omaha, Neb., or
Perth Amboy, N. J.
To collect the flue dust the waste gases are passed through long brick
flues. The chimneys are 150 to 200 ft. high, and 15 ft. in diameter.
They stand 75 ft. above the ground level of the blast furnaces. The
comparatively small proportion of flue dust produced (0.9 per cent. of
the charge) is briquetted, together with fine ore and 5 per cent. of
a thick paste of lime. For this purpose a White press is used, which
makes six briquets at a time, and handles 10 tons per hour.
According to a tabulation of the results of five months’ running, the
proportion of flue dust at several works of the American Smelting and
Refining Company is as follows:
Globe Plant, Denver 0.5% of the charge.
Pueblo Plant, Pueblo 0.9% ” ” ”
Eilers’ Plant, Pueblo 0.5% ” ” ”
East Helena Plant, Helena 0.3% ” ” ”
Arkansas Valley Plant, Leadville 0.2% ” ” ”
Murray Plant, Murray, Utah 1.2% ” ” ”
The fuel used is of very moderate quality. The coke (from beehive
ovens) carries up to 17 per cent. ash, the coal 10 to 18 per cent. The
monthly production is 2300 tons of work-lead and 150 tons of copper
matte (45 to 50 per cent. copper).
At the Eilers plant all sulphide ores, except the rich Idaho ore, are
roasted down to 5 to 7 per cent. S in 15 reverberatory furnaces, 60 to
70 ft. in length, each furnace roasting 15 tons per 24 hours, in six
charges.
The flue dust is briquetted together with fine Cripple Creek ore,
pyrites cinder from Argentine, Kan., Creede ores rich in silica and
10 per cent. lime. The residue from the zinc smeltery (U. S. Zinc
Company), which is brought to this plant (600 tons a month containing
nearly 10 per cent. lead), is taken direct to the blast furnaces.
Of the latter there are six, each with 18 tuyeres, which handle per
24 hours 160 to 180 tons of charge, containing on an average 10 per
cent. of lead in the ore, with 10 per cent. of coke, figured on the
charge. The average monthly production of a furnace is about 360 tons
of work-lead, which is purified at the Pueblo plant. The furnaces
are charged by hand. Of the slag, 30 per cent., as shells, etc., is
returned to the charge. The monthly production of work-lead is 2000
tons, carrying 150 oz. of silver and 2 to 6 oz. of gold per ton.
The matte amounts to about 8.3 per cent., and contains 12 per cent.
copper. It is concentrated up to 45 per cent. Cu, which is shipped (150
tons a month) for smelting to blister copper.
THE PERTH AMBOY PLANT OF THE AMERICAN SMELTING AND REFINING COMPANY[55]
BY O. PUFAHL
(January 27, 1906)
These works were erected in 1895 by the Guggenheim Smelting Company.
They are situated on Raritan Bay, opposite the southern point of Staten
Island, in a position offering excellent facilities for transportation
by land and by water. The materials worked up are base lead bullion
and crude copper, containing silver and gold, chiefly drawn from the
company’s smelteries in the United States and Mexico. Silver ore is
received from South America. The ores and base metals from Mexico and
South America are brought to Perth Amboy by the company’s steamships
(American Smelters Steamship Company).
_Ore Smelting._—The silver ore from South America (containing antimony
and much silver, together with galena, iron and copper pyrites) is
crushed by rolls and is roasted down from 26 per cent. to 3 per cent.
S in 11 reverberatory furnaces, 70 ft. long and 15 ft. wide (inside
dimensions). It is then mixed with rich galena from Idaho, pyrites
cinder, litharge, copper skimmings, and residues from the desilverizing
process, together with limestone, and is smelted for work-lead and
lead-copper matte in three water-jacketed furnaces, using 12 per cent.
coke, figured on the ore in the charge. Of these furnaces one has 12
tuyeres; it measures 42 × 96 in. in cross-section at the tuyeres, and
6 ft. 3 in. by 8 ft. at the charging level. The hight of charge is 16
ft. The other two furnaces have 16 tuyeres each, their cross-section at
the tuyeres being 44 in. by 128 in., at the charging level 6 ft. 6 in.
by 12 ft., and hight of charge 16 ft. The furnaces are operated at a
blast pressure of 35 oz. per square inch. The temperature of the gases
at the throat is 140 deg. F. (60 deg. C.) measured with a Columbia
recording thermometer, which works very well. These furnaces reduce,
respectively, 100 to 120 and 130 to 140 tons of charge per 24 hours;
they are also used for concentrating roasted matte.
_Copper Refining._—The crude copper is melted in two furnaces of 125
tons aggregate daily capacity, and is molded into anodes by Walker
casting machines. Twenty-six anodes are lifted out of the cooling
vessel at a time, and are taken to the electrolytic plant.
The electrolytic plant comprises two systems, each of 408 vats. The
current is furnished by two dynamos, each giving 4700 amperes at 105
volts. The cathodes remain in the bath for 14 days. The weight of the
residual anodes is 15 per cent.
The anode mud is swilled down into reservoirs in the cellar as at
Chrome (De Lamar Copper Refining Company), is cleaned, dried and
refined in a similar manner.
For melting the cathodes there are two reverberatory furnaces of
capacity for 75 tons per 24 hours. The wire-bars and ingots are cast
with a Walker machine. About 3200 tons of refined copper are produced
per month.
_Copper Sulphate Manufacture._—The lyes withdrawn from the electrolytic
process are worked up into copper sulphate, shot copper being added.
This latter is prepared in a reverberatory furnace from matte obtained
as a by-product in working up the lead. About 200 tons of copper
sulphate are thus produced per month; the process used is the same as
at the Oker works. Lower Harz, Germany. The crystals are rinsed, dried
and packed in strong wooden barrels.
_Lead Refining._—The working up of the Mexican raw lead is carried
out under the supervision of the customs officers. The lead, which is
imported duty free, must be exported again. From each bar a sample is
cut from above and below by means of a punch entering half way into the
bar. For refining the lead there are four reverberatory furnaces of 60
tons capacity, with hearths 17 ft. 9 in. by 12 ft. 6 in., a mean depth
of 14 in., and a grate area of 2 ft. 6 in. by 6 ft.; in addition to
these there is a furnace of 80 tons capacity with a hearth 19 ft. 7½
in. by 9 ft. 6 in., a mean depth of 18 in., and grate area of 3 ft. by
6 ft.
For desilverizing the softened lead there are five kettles, each of
60 tons capacity, 10 ft. 3 in. diameter and 39 in. depth. The zinc
is stirred in with a Howard mechanical stirrer and the zinc scum is
pressed dry in a Howard press, which gives a very dry scum. The latter
is then, while still warm, readily hammered into pieces for the retorts.
The desilverized lead is refined in five reverberatory furnaces, of
which four take a charge of 50 tons each, and one of 65 tons. The
production of desilverized lead is 5000 to 5500 tons a month.
The distillation of the zinc crusts is carried out in 18 oil-fired
Faber du Faur tilting furnaces. Each retort receives a charge of
1200 lb. of broken-up crust and a little charcoal. The distillation
lasts 6 to 7 hours. Fifty gallons of petroleum residues are consumed
per charge. The oil is blown into the furnace with a compressed
air atomizer. After withdrawing the condenser, which runs on a
traveling support, the argentiferous lead is poured directly from
the tilted retort into an English cupel furnace. Seven such furnaces
(magnesia-lined, with movable test) are in use, of which each works
up 4.5 to 5 tons of retort metal in 24 hours. The furnaces are
water-jacketed. The blast is introduced by the aid of a jet of steam.
Three tons of coal are used per 24 hours.
_Gold and Silver Parting._—The doré bars are cast into anodes for
electrolytic parting by the Moebius process. The plant consists of 144
cells in 24 divisions. The mean composition of the electrolytic bath is
said to be as follows: 10 per cent. free nitric acid, 17 grams silver,
and 35 to 40 grams copper per liter. The current is furnished by a 62
k.w. dynamo. One cell consumes 260 amp. at 1.75 volts. One k.w. gives
a yield of 1600 oz. fine silver per 24 hours. The daily production
of silver is almost 100,000 oz., and is exceeded at no other works.
About $3,000,000 worth of metal is always on hand in the different
departments.
THE NATIONAL PLANT OF THE AMERICAN SMELTING AND REFINING COMPANY[56]
BY O. PUFAHL
(April 14, 1906)
This plant, at South Chicago, Ill., refines base lead bullion. It
comprises four reverberatory furnaces, of which one takes a charge of
100 tons, one 80 tons, and the other two 30 tons each; one of the small
furnaces is being torn down, and a 120 ton furnace is to be built in
its place. The furnaces are fired with coal from Southern Illinois,
which contains 11 per cent. of ash.
In softening the bullion, the time for each charge is 10 hours. The
first portion tapped consists of dross rich in copper, which is
followed by antimonial skimmings and litharge.
The copper dross is melted up in a small reverberatory furnace,
together with galena from Wisconsin (containing 80 per cent. lead),
for work-lead and lead-copper matte, the latter containing about 35
per cent. of copper; this matte is enriched to 55 per cent. copper
by the addition of roasted matte, and is finally worked up for crude
copper (95 per cent.) in a reverberatory furnace. All the copper so
produced is used in the parting process for precipitating the silver.
The antimonial skimmings are smelted in a reverberatory furnace,
together with coke cinder, for lead and a slag rich in antimony, which
is reduced to hard lead (27 per cent. antimony, 0.5 per cent. copper,
0.5 per cent. arsenic) in a small blast furnace, 14 ft. high, which has
8 tuyeres.
The softened lead is tapped off into cast-iron desilverizing pots,
which usually outlive 200 charges; in isolated cases as many as
300. For desilverizing, zinc from Pueblo, Colo., is added in two
instalments, being mixed in by means of a Howard stirrer. After the
first addition there remains in the lead 7 oz. of silver per ton;
after the second only 0.2 oz. The first scum is pressed in a Howard
press and distilled; the second is ladled off and is added to the next
charge. The Howard stirrer is driven by a small steam engine suspended
over the kettle; the Howard press by compressed air.
For distilling zinc scum, 12 Faber du Faur tilting retorts, heated with
petroleum residue, are used. The argentiferous lead (with 9.6 per cent.
silver) is transferred from the retort to a pan lined with refractory
brick, which is wheeled to the cupelling hearth and raised by means of
compressed-air cylinders, so as to empty its molten contents through a
short gutter upon the cupelling hearth. The cupelling hearths are of
the water-cooled English type, and are heated by coal with under-grate
blast. The cast-iron test rings, with reinforcing ribs, are made in two
pieces, slightly arched and water-cooled; they are rectangular, with
rounded corners, and are mounted on wheels. The material of the hearth
is marl.
Argentiferous lead is added as the operation proceeds, and finally the
doré bullion is poured from the tilted test into thick bars (1100 oz.)
for parting.
The desilverized lead is refined in charges of 28 tons (4 to 5 hours)
and 80 to 90 tons (8 to 10 hours), introducing steam through four to
eight half-inch iron pipes. The first skimmings contain a considerable
proportion of antimony and are therefore added to the charge when
reducing the antimonial slags in the blast furnace. The litharge is
worked up in a reverberatory furnace for lead of second quality. The
refined lead is tapped off into a kettle, from which it is cast into
bars through a siphon.
The parting of the doré bullion is carried out in tanks of gray cast
iron, in which the solution is effected with sulphuric acid of 60 deg.
B. The acid of 40 deg. B. condensed from the vapors is brought up to
strength in leaden pans. In a second larger tank, which is slightly
warmed, a little gold deposits from the acid solution of sulphates.
The solution is then transferred (by the aid of compressed air) to the
large precipitating tank, and diluted with water. It is here heated
with steam, and the silver is rapidly precipitated by copper plates
(125 plates 18 × 8 × 1 in.) suspended in the solution from iron hooks
covered with hard lead. After the precipitation, the vitriol lye is
siphoned off, the silver is washed in a vat provided with a false
bottom, is removed with a wooden shovel, and is pressed into cakes 10 ×
10 × 6 in.
The refining is finished on a cupelling hearth fired with petroleum
residue, adding saltpeter, and removing the slag by means of powdered
brick. After drawing the last portion of slag the silver (0.999 fine)
is kept fused under a layer of wood-charcoal for 20 minutes, and is
then cast into iron molds, previously blackened with a petroleum flame.
The bars weigh about 1100 oz.
The gold is boiled with several fresh portions of acid, is washed and
dried, and finally melted up with a little soda in a graphite crucible.
It is 0.995 fine.
The lye from the silver precipitation, after clearing, is evaporated
down to 40 deg. B. in leaden pans by means of steam coils, and is
transferred to crystallizing vats. The first product is dissolved
in water, the solution is brought up to 40 deg. B. strength, and is
allowed to crystallize. The purer crystals so obtained are crushed, and
are washed and dried in centrifugal apparatus; they are then sifted and
packed in wooden casks in two grades according to the size of grain.
The very fine material goes back into the vats. From the first strongly
acid mother liquor, acid of 60 deg. B. is prepared by concentrating in
leaden pans, and this is used for the parting operation.
THE EAST HELENA PLANT OF THE AMERICAN SMELTING AND REFINING COMPANY[57]
BY O. PUFAHL
(April 28, 1906)
The monthly production of these works is about 1500 tons of base
bullion (containing 150 oz. Ag and 4 to 6 oz. Au per ton), and 200 tons
of 45 per cent. copper matte. The base bullion is shipped to South
Chicago, the matte to Pueblo.
The ore-roasting is done in two batteries of eight reverberatory
furnaces and 16 Brückner furnaces, the resulting product containing on
an average 20 per cent. lead and 3 per cent. sulphur. The charge for
the blast furnaces consists of roasted ore, rich galena, argentiferous
red hematite, briquetted flue dust, slag (shells) from the furnace
itself, lead skimmings, scrap iron and limestone.
Four tons of the charge are dumped over a roller into a low car, which
is then drawn up an inclined plane to the charging gallery by an
electric motor and is then dumped into the furnace.
The two rectangular blast furnaces (Eilers’ type) have eight tuyeres on
each of their longer sides and cast-iron water-jackets of 6 ft. hight.
The blast is delivered at a pressure of 40 oz. The lead is drawn off
through a siphon tap into a cooling kettle. The furnace has a large
forehearth for separating the matte and the slag. The slag is received
by a two-pot Nesmith truck, having an aggregate capacity of 14 cu. ft.
These trucks are hauled to the dump by an electric locomotive. The
shells are returned to the furnace with the charge.
The matte (with about 6 per cent. Cu and the same percentage of lead)
is tapped off into iron molds and after cooling is crushed to 0.25-in.
size, to be roasted in the reverberatory furnaces and smelted up
together with roasted ore for a 15 per cent. matte. The latter is
crushed, roasted and separately smelted together with silicious ore
for 45 per cent. matte, which is then sent to Pueblo to be worked up
into blister copper. The small quantity of speiss which is formed is
broken up and returned to the blast furnaces with the charge. The slag
contains 0.5 to 0.8 per cent. lead and 0.5 oz. silver per ton.
THE GLOBE PLANT OF THE AMERICAN SMELTING AND REFINING COMPANY[58]
BY O. PUFAHL
(May 5, 1905)
This plant produces 1800 tons of base bullion per month and 200 tons
of lead-copper matte containing 45 to 52 per cent. of copper. The ores
smelted are mostly from Colorado, but include also galena from the Cœur
d’Alene and other supplies. The limestone is quarried 14 miles from
Denver; coke and coal are brought from Trinidad, Colo.
All sulphides, except the slimes, concentrates and the rich Idaho ores,
are roasted. For roasting there are:
(1) Fifteen reverberatory furnaces, five of which measure 60 × 14 ft.,
and the other ten 80 × 16 ft. externally. In 24 hours these roast six
charges of 4400 lb. (average) of moist ore (2.15 tons of dry ore) from
28 to 30 per cent. down to 3 to 4 per cent. sulphur. Each furnace is
attended by three men working in 12-hour shifts; the stoker earns
$2.75; the roasters, $2.30.
(2) Two Brown-O’Harra furnaces, 90 ft. long, with two hearths, and a
small sintering furnace attached. They have three grates on each long
side, and each roasts 26 tons of ore in 24 hours down to ¾ per cent.
sulphur.
(3) Twelve Brückner furnaces, each taking 24 tons’ charge, with
under-grate blast, the air being fed into the cylinders by a steam jet.
According to the zinc content of the ores the roasting operation lasts
70 to 90 hours, the furnace making one revolution per hour. The roasted
product from the Brückner furnaces is pressed into briquets, together
with fine ore, flue dust and lime.
The smelting is carried out in seven blast furnaces, with 16 tuyeres,
blast at 2-lb. pressure, hight of furnace 18 ft. 6 in., section at
the tuyeres 42 × 144 in. The charge is 120 to 150 tons exclusive of
slag and coke. The slag and the matte are tapped off together into
double-bowl Nesmith cars, which are hauled, by an electric locomotive,
to a reverberatory furnace (hearth 20 × 12 ft.) in which they are kept
liquid, for several hours, in charges of 14 to 15 tons, in order to
effect complete separation. A little work-lead is obtained in this
operation, while the matte is tapped off into cast-iron pans of one
ton capacity, and the slag, 0.5 to 0.6 per cent. lead, 0.6 to 0.7 oz.
silver, is removed in 5-ton pots to the dump.
The matte is broken up, crushed to 0.25 in. size, roasted in the
reverberatory furnaces, smelted for a 45 to 52 per cent. copper matte,
which is shipped to be further worked up into blister copper. The crude
matte contains 10 to 12 per cent. copper, 12 to 15 per cent. lead, 40
oz. silver and 0.05 oz. gold.
From the siphon taps of the blast furnaces the work-lead is transferred
to a cast-iron kettle of 33 tons’ capacity. Here the copper dross
is removed, the metal is mixed by introducing steam for 10 minutes,
sampled, and the lead is cast into bars through siphons. It contains
about 2 per cent. antimony, 200 oz. silver and 8 oz. gold. This product
is refined at Omaha.
The blast-furnace gases pass through a flue 1200 ft. long, and enter
the bag-house, in which they are filtered through 4000 cotton bags 30
ft. long and 18 in. in diameter. These bags are shaken every 6 hours.
The material which falls to the floor is burnt where it lies, sintered
and returned to the blast furnaces.
In the engine house there are four Connersville blowers, two of which
are No. 8 and two of No. 7 size. Each blast furnace requires 45,000 cu.
ft. of air a minute.
The works give employment to 450 men, whose wages (for 10-to 12-hour
shifts) are $2 to $3.
LEAD SMELTING IN SPAIN
BY HJALMAR ERIKSSON
(November 14, 1903)
A few notes, gathered during a couple of years while I was employed
at one of the large lead works in the southeastern part of Spain, are
of interest, not as showing good work, but for comparing the results
obtained in modern practice with those obtained by what is probably the
most primitive kind of smelting to be found today. The plant about to
be described may serve as a general type for that country. As far as I
know, the exceptions are a large plant at Mazarron, fully up to date
and equipped with the most modern improvements in every line; a smaller
plant at Almeria, also in good shape, and the reverberatory smelting of
the carbonates at Linares. It should be kept in mind, however, that the
conditions are peculiar, iron and machinery being very expensive and
manual labor very cheap.
[Illustration: FIG. 41.—Spanish Lead Blast Furnace.]
About 4 ft. above the tuyeres the furnace is built of uncalcined brick
made of a black graphitic clay found in the mines near by; the upper
part is of common red brick. The entire cost of one furnace does not
reach $100. The flue leads to a main gallery 3.5 by 7 ft., which goes
down to the ground, and extends several times around a hill, the
chimney being placed on the top of the hill, considerably above the
furnace level. The gallery is about 10,000 ft. long, and is laid down
in the earth, with the arched roof just emerging. It is all built of
rough stone, the inside being plastered with gypsum. The furnace has
three tuyeres of 3 in. diameter. The blast pressure is generally 4 to
6 in. of water. Neither feeding floor nor elevators are used, only a
couple of scaffolds, the charge being lifted up gradually by hand in
small convenient buckets made of sea-grass. When charging the furnace,
coke is piled up in the center, and the mixture of ore, fluxes and slag
is charged around the walls. The slag and matte are left to run out
together on an inclined sand-bed. The matte, flowing more quickly, goes
further and leaves the slag behind, but the separation thus obtained
is, of course, very unsatisfactory. The charge mixture is weighed and
made for each furnace every morning. When it is all put through, the
furnace is run down very low, without any protecting cover on the top;
several iron bars are driven through the furnace at the slag-tap level,
for holding up the charge; the lead is all tapped out; a big hole is
made in the crucible for the purpose of cleaning it out; all accretions
are loosened with a bar; the hole is closed with mud of the graphitic
clay; bars are removed, when the crucible is filled with coke from the
center and the charging is continued. In this way a furnace can be kept
running for any length of time, but at a great loss of heat, and with a
great increase of flue dust.
The current practice, in many parts of Spain, is to run the same number
of ore-smelting and of matte-smelting furnaces. All the slag and the
raw matte, produced by the ore-smelting furnaces, is re-smelted in the
matte furnaces, together with some dry silver ores. No lead at all is
produced in the matte furnaces, only a matte containing up to 150 oz.
silver per ton and 25 to 35 per cent. of the lead charged on them. This
rich matte is calcined in kilns, and smelted together with the ore
charge.
The ores we smelted were galena ranging from 5 to 83 per cent. lead
and about 250 oz. silver per ton of lead; dry silver ores containing
up to 120 oz. silver per ton, and enough of the Linares carbonates for
keeping the silver below 120 oz. per ton in the lead. The gangue of the
galena was mainly iron carbonate. Most of that ore was hand picked and
of nut size. Machine concentrates with more than 30 per cent. lead or
containing much pyrite were calcined; everything else was smelted raw.
The flux exclusively used, before I came, was carbonate of iron, which,
by the way, was considered a “cure-for-all.” The slag analyses showed:
CaO, below 4 per cent.
FeO, above 45 per cent.
SiO₂, about 30 per cent.
BaO, 5 to 10 per cent.
Al₂O₃, 5 to 10 per cent.
Pb, by fire assay, 0.75 to 2.5 per cent.
Ag, by fire assay, 2 to 3 oz. per ton.
The specific gravity of the slag was about 5, or practically the same
as that of the matte. The output of metallic lead was about 70 per
cent.; of silver, 84 per cent. The working hight of the furnaces—tuyere
level to top of charge—was at that time only 7 ft., and I was told that
it had been still lower before.
To the working hight of the furnaces was added 2 ft., simply by putting
up the charging doors that much. A very good limestone was found just
outside the fence around the plant. Enough limestone was substituted
for the iron carbonate, to keep the lime up to 12 per cent. in the
slag, reducing the FeO to below 35 per cent. and the specific gravity
to below four.
The result of these alterations was an increase in the output of
metallic lead, from 76 to 85 per cent.; of silver from 84 to 90 per
cent.; a comparatively good separation of slag and matte, and a slag
running about 0.5 to 0.75 per cent. Pb and 1.5 oz. Ag per ton.
Owing to the great extent of the gallery, and the consequent good
condensation of the flue dust, the total loss of lead and silver was
much smaller than would be expected; in no case being found above 4 per
cent.
The composition of the charge was 55 per cent. ore and roasted matte,
13 per cent. fluxes, and 32 per cent. slag. Coke used was 11 per cent.
on charge, or 20 per cent. on ore smelted. Each furnace put through 10
to 15 tons of charge, or 7 tons of ore, in 24 hours. Eight men and two
boys were required for each furnace, including slag handling and making
up of the charge. The cost of smelting was 17 pesetas per ton of ore,
which at the usual premium (£1 = 34 pesetas = $4.85) equals $2.43. This
cost is divided as follows:
Coke $1.47
Fluxes 0.04
Labor 0.65
Coal for power 0.10
General expenses 0.17
————-
Total $2.43
This $2.43 per ton includes all expenses of whatever kind. The iron
carbonate flux contained lead and silver, which was not paid for. The
fluxes are credited for the actual value of this lead and silver.
Without making this discount, the cost of flux would amount to 26c. per
ton, making the entire smelting cost come to $2.65. As an explanation
of the low cost of labor, it may be noted that the wages were, for
the furnace-man, 2.25 pesetas, or 32c. a day; for the helpers, 1.75
pesetas, or 25c. a day.
The basis for purchasing the galena ore may here be given, reduced to
American money; lead and silver are paid for according to the latest
quotations for refined metals given by the _Revista Minera_, published
at Cartagena. (The quotations are the actual value in Cartagena of the
London quotations.)
The following discounts are made: 5 per cent. for both silver and
lead; $6.40 per ton on ore containing 7 per cent. Pb and below; this
rises gradually to a discount of $7.75 per ton of ore containing 30 per
cent. Pb and above.
The transportation is paid by the purchaser and amounts to about $1.20
per ton of ore.
The dry silver ores were cheaper than this and the lead carbonates much
more expensive.
LEAD SMELTING AT MONTEPONI, SARDINIA[59]
BY ERMINIO FERRARIS
(October 28, 1905)
In dressing mixed lead and zinc carbonate ores by the old method of
gradual crushing with rolls, middling products were obtained, which
could be further separated only with much loss. Inasmuch as the losses
in the metallurgical treatment of such mixed ore were reckoned to be
less than in ore dressing, these between-products at Monteponi were
saved for a number of years, until there should be enough raw material
to warrant the erection of a small lead and zinc smeltery.
In 1894 the lead smeltery in Monteponi was put in operation; in 1899
the zinc smeltery was started. At about the same time the reserves of
lead ore were exhausted, and the lead plant then began to treat all the
Monteponi ores and a part of those from neighboring mines.
As will be seen from the plan (Fig. 42), the smelting works cluster
in terraces around the mine shaft, covering an area of about 3000 sq.
m. (0.75 acre); the ore stocks and the pottery of the zinc works are
located in separate buildings.
During the first years of working, the slag had purposely been kept
very rich in zinc, in the hope of utilizing it later for the production
of zinc oxide. It had an average zinc content of 16.80 per cent., or 21
per cent. of zinc oxide, with about 32 per cent. SiO₂, 25 per cent.
FeO, and 14 per cent. lime. According to the recent experiments, this
slag can very well be used for oxide manufacture, in connection with
calamine rich in iron. The slag made at the present time has only 15
per cent. ZnO; 25 per cent. SiO₂; 16 per cent. CaO; 3 per cent. MgO;
33 per cent. FeO; 2.5 per cent. Al₂O₃, and 2 per cent. BaO, and
small quantities of alkalies, sulphur and lead (1 to 1.5 per cent).
The following classes of ore are produced at Monteponi:
1. Lead carbonates, with a little zinc oxide; these ores are screened
down to 10 mm. The portion held back by the screen is sent straight
to the shaft furnaces; the portion passing through is either roasted
together with lead sulphides, or is sintered by itself, according to
circumstances.
2. Dry lead ores, mostly quartz, with 10 to 15 per cent. lead, which
are mixed for smelting with the lead carbonates.
[Illustration: FIG. 42.—General Plan of Works.]
3. Lead sulphides, which are crushed fine and roasted dead. Quartz
sand is added in the roasting, in order to decompose the lead sulphate
and produce a readily fusible silicate; as quartz flux, fine sand from
the dunes on the coast is used. This is a product of decomposition of
trachyte, and contains 88 per cent. of silica, together with alkalies
and alumina. The roast is effected in two hand-raked reverberatory
furnaces, 18 m. long, which turn out 12,000 kg. of roasted ore in
24 hours, consuming 1800 kg. of English cannel coal, or 2400 kg.
of Sardinian lignite. There is also a third reverberatory furnace,
provided with a fusion chamber, which is used for roasting matte and
for liquating various secondary products.
The charge for the shaft furnace, as a rule, consists of 50 per cent.
ore (crude and roasted), 20 per cent. fluxes and 30 per cent. slag
of suitable origin. The fluxes used are limestone from the mine,
containing 98 per cent. CaCO₃, and limonite from the calamine
deposits. This iron ore contains 48 per cent. Fe, not more than 4 per
cent. Zn, a little lead and traces of copper and silver.
A shaft furnace will work up a charge of 60 tons, equal to 30 tons of
ore, in 24 hours, with a coke consumption of 12 per cent. of the weight
of the charge and a blast pressure of 50 mm. of mercury. There are
three furnaces, of which two are used alternately for smelting lead
ores, while one smaller furnace serves for smelting down products, such
as hard lead, copper matte and copper bottoms.
[Illustration: FIG. 43.—Elevation of works on line A B C D E F of Fig.
42.]
Figs. 43 to 46 show one of the furnaces. It will be seen at once that
its construction is similar to that of the standard American furnaces.
Pilz furnaces were tried in the first few years, but were finally
abandoned, as they could not be kept running for any satisfactory
length of time with slags rich in zinc. Diluting the slag, on the other
hand, would have led to an increased coke consumption, and would have
rendered the slag itself worthless. The furnace, however, differs in
several respects from its American prototype; the following are some of
the chief characteristics peculiar to it:
[Illustration: Section E F. Section G H.
FIG. 44.—Shaft Furnace for Lead Smelting.]
The chimney above the feed-floor covers one-third of the furnace
shaft, and is turned down in the form of a siphon, to connect with
the flue-dust chamber. The lateral faces, which are left open, serve
as charging apertures; the central one of these, provided with a
counterbalanced sheet-iron door, is used for charging from cars. The
square openings at the ends, which are covered with cast-iron plates,
are used for barring down the furnace shaft and may also be used for
charging. By this arrangement, together with the two hoppers placed
laterally on the chimney, it is possible to distribute the charge in
any desired manner over the whole cross-section of the furnace. This
arrangement greatly facilitates the removal of any accretions in the
furnace shaft, as the centrally placed chimney catches all the smoke,
while the charge-holes render the furnace accessible on all sides.
In case of large accretions being formed, the whole furnace can be
emptied, cleaned and restarted in 24 to 36 hours.
The smelting cone is enclosed by cast-steel plates 50 cm. high, instead
of having a water-jacket. These are cooled as desired by turning a
jet of water on them. The plates are connected to the furnace shaft
by a bosh wall 25 cm. thick, which is surrounded with a boiler-plate
jacket. These jacket plates also are cooled from the outside by sprays
of water. With this arrangement the consumption of water is less than
with water-jackets, as a part of the water is vaporized, and the danger
of leakage of the jackets is avoided. The cast-steel plates are made
in two patterns; there are two similar side-plates, each with four
slits for the tuyeres, and two end-plates, provided with a circular
breast of 30 cm. aperture, for tapping the slag. The breast is cooled
by water flowing down, and is closed in front by a plate of sheet
iron, in which is the tap-hole for running off the slag. When cleaning
out, this sheet-iron plate is removed and the breast is opened, thus
providing easy access to the hearth. The four cast-steel plates are
anchored together with bolts at their outer ribs, and rest on two long,
gutter-shaped pieces of sheet iron, which carry off all the water which
flows down, and keep it away from the brickwork of the hearth.
[Illustration: Section J L. Section C D.
FIG. 45.—Shaft Furnace.]
The hearth, cased with boiler plate and rails, has at the side a
cast-iron pipe of 10 cm. diameter for drawing off the lead to the
outside kettle; this pipe has a slight downward inclination, to prevent
the slag flowing out; every 20 minutes lead is tapped, and the end of
the pipe is then plugged up with clay.
The furnace shaft is supported upon a hollow mantel, which serves at
the same time as blast-pipe. The blast-pipe has eight lateral tees,
which are connected by canvas hose with the eight tuyeres. The mouth
of the tuyeres has the form of a horizontal slit, whereby the air is
distributed more evenly over the entire zone of fusion.
[Illustration: FIG. 46.—Shaft Furnace for Lead Smelting. (Section A B.)]
The precipitation of flue dust is effected in a brick condensing
chamber, placed near the beginning of the main flue. The main flue
terminates on the hill (see Fig. 43) in a chimney, the top of which
is 160 m. above the ground level of the works, affording excellent
draft. The condensing chamber (Figs. 49 to 51) consists of a vaulted
room, 3.40 m. wide and 6.60 m. long, which is divided into twelve
compartments by one longitudinal and five baffle walls. The gases
change direction seven times, and pass over the longitudinal wall
six times, being struck six times by fine sprays of water. The six
atomizers for this purpose consume 1.5 liter of water per minute, of
which four-fifths is vaporized, while one-fifth flows off to the lower
water basin. By this means 10 to 15 per cent. of the total flue dust
is precipitated in the condensing chamber itself, and is removed from
time to time as mud through the lower openings, which are water-sealed.
The remainder of the volatilized water precipitates the flue dust
almost completely on the way to the stack, so that only a short column
of steam is visible at the mouth of the stack. The flue to the stack
passes for the most part underground through abandoned adits and
galleries, thus providing a variety of changes in cross-section and
in direction, and assisting materially the action of the condensing
chamber.
[Illustration: FIG. 47.—Section of Lead Refinery.]
[Illustration: FIG. 48.—Softening Furnace.]
As the charge of the shaft furnaces is poor in sulphur, no real matte
is produced, but only work lead and lead ashes (Bleischaum), which
contains 90 per cent. of lead, 1.6 per cent. sulphur, 0.4 per cent.
zinc, 0.85 per cent. Cu, 0.99 per cent. Fe, and 0.22 per cent. Sb. By
liquation and a reducing smelt in a reverberatory furnace, most of the
lead is obtained, along with a lead-copper matte, which is smelted for
copper matte and antimonial lead in the blast furnace.
[Illustration: FIG. 49.—Fume Condenser. (Section A B.)]
The copper matte, containing 18 per cent. Cu, 25 per cent. Fe, 30 per
cent. Pb and 18.4 per cent. S, is roasted dead in a reverberatory
furnace, is sintered, and melted to copper-bottoms in a small shaft
furnace. These copper-bottoms, which contain 60 per cent. copper and
25 per cent. lead, are subjected to liquation, and finally refined to
blister copper.
The zinc-desilvering plant, Fig. 47, consists of a reverberatory
softening furnace, two desilvering kettles of 14 tons capacity, a pan
for liquating the zinc crust, and a small kettle for receiving the lead
from the liquation process.
This pan has the advantage over the ordinary liquating kettle, that the
lead which drips off is immediately removed, before it can dissolve the
alloy; the silver content of the liquated lead is scarcely 0.05 per
cent., while the dry alloy contains 5 to 8 per cent.
[Illustration: FIG. 50.—Fume Condenser. (Section E F G H.)]
[Illustration: FIG. 51.—Fume Condenser. (Section C D.)]
The removal of the zinc is effected in a second reverberatory furnace.
Formerly the steam-method was used, but the rapid wear of the kettles,
and the excessive formation of oxides called for a change in the
process. The zinc-silver alloy is distilled in a crucible of 200 kg.
capacity, and is cupeled in an English cupel furnace. The details of
the reverberatory furnace are shown in Fig. 48.
The composition of the final products is shown by the following
analyses; Lead: Zn, 0.0021 per cent.; Fe, 0.0047 per cent.; Cu, 0.0005
per cent.; Sb, 0.0030 per cent.; Bi, 0.0007 per cent.; Ag, 0.0010 per
cent.; Pb, 99.998 per cent.; Silver, Ag, 99.720 per cent.; Cu, 0.121
per cent.; Fe, 0.005 per cent.; Pb, 0.018 per cent.; Au, 0.003 per
cent.
INDEX
Alloy, retorting the, in lead refining, 267
Alumina, experience with, 259
American Smelting and Refining Co., 4, 6, 26, 93, 113, 252, 295
at Murray, Utah, 287
Atmosphere, effect of on concrete, 242
Bag-house, cost of attending, 246
standard, 246
Bag-houses for saving fume, 244
Bartlett, Eyre O., 244
Bayston, W. B., 199
Bennett, James C., 66
Betts, Anson G., 270, 274
Between products, working up of, 39
Biernbaum, A., 41, 148, 160
Blast furnace of circular form, 253
Spanish lead, 307
Blast, volume and pressure of in lead smelting, 76
Blower, rotary, deficiency of, 251
Blowers for lead and copper smelting, 256
now more powerful for lead smelting use, 252
Blowers, rotary, method of testing volumetric efficiency of, 254
_vs._ blowing engines, 254
_vs._ blowing engines for lead smelting, 251
Blowing engines, when to use, 259
Bonne Terre lead deposits, 18
orebody, Missouri, 13, 14
Borchers, W., 114, 116, 127
Bormettes method, combination processes in, 222
Bradford, Mr., 55
Bretherton, S. E., 251, 258
Broken Hill Proprietary Block, 14, 59
Broken Hill practice, 51
Proprietary Co., 52, 113, 124, 145, 175, 178, 206
Bricking plant for flue dust and fine ores, 66-70
Briquetting costs, 62
methods of avoiding, 63, 64
process, operations, in 59
Bullion, analyses of in lead refining, 281
refined lead and slimes, analyses of, 282
Canadian Smelting Works, 275
Carlton Iron Co., 63
Carmichael, A. D. 56, 199
Carmichael-Bradford process, 175-185
brief estimate of, 209
claims of in patent, 199
recommendations of, 124
process, points concerning, 131
Cement walls, how to build, 241
Channing, J. Parke, 254
Charge-car in smelting, true function of, 94
feeding of in lead smelting, 77
mechanical character of in lead smelting, 78
Charges, effect of large in lead smelting, 77
Cherokee Lanyon Smelter Co., 104
Chimney bases, 237
Chisholm, Boyd & White Co., 64
Clark, Donald, 114, 144, 175
Cœur d’Alene mines, 5, 6, 7
Concrete flues and stacks, advantages and disadvantages of, 242
in metallurgical construction, 234
Connersville Blower Co., 252
Consolidated Kansas City Smelting and Refining Co., 285
Coke, percentage necessary to use in smelting, 259
Croll, H. V., 253
Cupellation in lead refining, 269
De Lamar Copper Refining Co., 297
Desilverization in lead refining, 265
Desloge practice contrasted with others, 46
Doeltz, F. O., 139
Dross, analyses of in lead refining, 279
Dupuis & Sons, 63
Dust chamber, arched form, 231
beehive form of, 232
design, 229
rectangular form, 230
concrete, 235-237
Dwight, Arthur S., 73, 81
spreader and curtain in furnaces, 91
East Helena and Pueblo smelting systems compared, 93
plant of the American Smelting and Refining Co., 302
system of smelting, 88-94
Edwards, Henry W., 234, 240, 242
Einstein silver mine, 14
Engine, blowing, proper field of, 257
blowing, and rotary blowers, 258
Eriksson, Hjalmar, 306
Federal Lead Co., 38
Mining and Smelting Co., 7
Feeders, cup and cone, for round furnaces, 81
Ferraris, Erminio, 311
Flat River mines, 18
Flue gases and moisture, effect of on concrete, 242
Flues, concrete, 234, 240, 242
Foundations for dynamos, 236
Fremantle Smelting Works, 145
Fume-smelting, cost of, 33
in the hearth, 32
Furnace operations at Desloge, Mo., 45
Furnaces at Desloge, Mo., 43
reverberatory, at Desloge, Mo., 42
Galena, experiments in roasting, 129
lime-roasting of, 14
new methods of desulphurizing, 116
roasting of by Savelsberg process, 122, 123
Gas, furnace, effect of on cement, 240
Gelatine, use of in electrolytic lead refining, 275
Germot, A., 224
process, 224
Globe plant of the American Smelting and Refining Co., 304
Smelting and Refining Co., 244
Greenway, T. J., 59
Guillemain, C., 133
Harvard, Francis T., 242
Hearth, covered-in, 36
Heat, effect of on cement, 242
Heberlein, Ferdinand, 113, 167, 199
Hixon, Hiram W., 256, 258
Harwood, E. J., 51
Hourwich, Dr. Isaac A., 27
Huntington-Heberlein process, 113, 144-147
consideration and estimate of, 203-209
credit due to, 126
process as distinguished from others, 118
economic results of, 155-159
Huntington-Heberlein explained by the inventors, 167-173
process at Friedrichshütte, 148
process, from the hygienic standpoint, 160
ideas of in patent specifications, 117
process, introduction of at Tarnowitz, Prussia, 41
and Savelsberg processes, essential difference between, 192
process, some disadvantages of, 165, 166
Huppertz, L., 121
Hutchings, W. Maynard, 108, 126, 170
Huntington, Thomas, 113, 167, 199
Iles, Malvern W., 96, 252
Ingalls, W. R., 3, 16, 27, 42, 177, 186, 193, 215, 224, 244, 287
Iron, behavior of in silver-lead smelting, 75
Jackson Revel mine, 14
Johnson, E. M., 104
R. D. O., 18
Jones, Richard, 244
Samuel T., 244
Laur, F., 224
Lead, analyses of refined, 281
bullion, electrolytic refining of base, 270
bullion, Parkes process of desilverizing and refining, 263
bullion, softening of, 263
concentrate Joplin district, valuation of, 25
and copper smelting, the Bormettes method of, 215-223
deposits, southeastern Missouri, 18
Joplin district, 8
marketing, 3
-ore roasting, consideration of new processes, 135-138
Lead ore, average prices for, 27
ore, cost of smelting, 32
-ore roasting, theoretical aspects of, 133
ores, Galena, Kan., 24
ores, method of valuing, 26
ores, southwestern Missouri, 24
Park City, Utah, 8
-poisoning in old and new processes, 162-165
refining, electrolytic, 274
soft, Missouri, 25
smelting at Desloge, Mo., 42
smelting at Monteponi, Sardinia, 311
smelting and refining, cost of, 96
smelting in the Scotch hearth, 31
smelting in Spain, 306
smelting at Tarnowitz, Prussia, 41
source of in Missouri, 13
in southeastern Missouri, 7, 10, 17
sulphide and calcium sulphate, metallurgical behavior of, 139-143
total production United States, 5
yield from Scotch hearths, 39
Leadville, Colo., mines, 8
Lewis, G. T., 244
Lime-roasting of galena, 126
Lotti, Alfredo, 215
Messiter, Edwin H., 229, 240
Middleton, K. W. M., 31
Mine La Motte, 14
Minerals, briquetting of, 63
Mining methods in Missouri, 19-23
Missouri Smelting Co., 197
Mould, H. S., Co., 64
Murray smelter, Utah, 291
National plant of the American Smelting and Refining Co., 299
New Jersey Zinc Co., 246
Nutting, Mr., 256
Ore and Fuel Co., 63
different behavior of coarse and fine in lead smelting, 79
treatment in detail by the Huntington-Heberlein process, 150-155
Parkes process, cost of refining by, 99
Percy, Dr., 244
Perth Amboy plant of the American Smelting and Refining Co., 296
Petraeus, C. V., 24
Pfort curtain for furnaces, 82
Picher Lead Co., 197
Piddington, F. L., 263
Potter, Prof. W. B., 15
Pueblo lead smelter, 294
Smelting and Refining Co., 84
Pufahl, O., 38, 291, 294, 296, 299, 302, 304
Pyritic smelting without fuel practically impossible, 256
Raht, August, 251, 254
Refining, monthly cost of per ton of bullion treated, 100
Roasters, hand, and mechanical furnaces, average monthly cost of, 98
Roberts-Austen, W. C., 139
Salts, effect of crystallization of contained on concrete, 243
Santa Fe Gold and Copper Mining Co., 255
Savelsberg, Adolf, 122
Savelsberg process, 186-192
process, claims of in patent, 201
process contrasted with Huntington-Heberlein, 209
process, difference between and Huntington-Heberlein, 197
Savelsberg process the simplest, 132
Scotch-hearth method, permanency of, 195
Scotch hearths, 34
Schneider, A. F., 81
Seattle Smelting and Refining Works, 273
Silver-lead blast furnaces, mechanical feeding of, 81
blast furnace, proper conditions, 73
smelting, details of practice, 73
smelting, modern, 73
Slag-smelting costs, 34
Slime analysis at Broken Hill, 51
Slimes, analyses of in lead refining, 281
desulphurization of by heap roasting, 51
treatment of at Broken Hill, 53-55
Smelter, new, at El Paso, Texas, 285
Smelters’ pay, 32
Smelting, average cost of per ton, 98
Smelting Co. of Australia, 263
costs, 48
detailed costs of, 101, 102
of galena ore, 38
preparation of fine material for, 59
Solution, washing from slime, 277
Sticht, Mr., 256
St. Joseph Lead Co., 16
St. Louis Smelting and Refining Co., 81
Sulphide Corporation, 145
Sulphur dioxide, effect of on cement, 240
Sulphuric acid, making of at Broken Hill, 174
Tasmanian Smelting Co., 145
Tennessee Copper Co., 255
Terhune, R. H., furnace gratings, 84
Thacher, Arthur, 14
Ulke, Titus, 270
United Smelting and Refining Co., 88
States Zinc Co., 295
Vezin, H. A., 252
Walls, retaining, 237
Walter, E. W., 260
Waring, W. Geo., 24
Welch, Max J., 229
Wetherill, Samuel, 244
Wheeler, H. A., 10
Zinc, amount required in lead refining, 265, 266
crusts, treatment of in lead refining, 267
oxide in slags, 108
retort residues, analysis of materials smelted and
bullion produced, 106
retort residues, smelting, 104
FOOTNOTES:
[1] During 1905, antimonial lead commanded a premium of about 1c. per
lb. above desilverized, owing to the high price for antimony.
[2] The figures for 1903 and 1904 have been added in the revision of
this article for this book. The production of lead in the United States
in 1903 was 276,694 tons; in 1904, it was 302,204 tons.
[3] Ounces of silver to the ton of lead.
[4] These figures are doubtful; they are probably too high. (See table
on p. 5).
[5] The production of zinc ore in this district has now been commenced.
[6] The manuscript of this article was dated Oct. 5, 1905.
[7] Translated from _Zeit. f. Berg.-Hütten-und Salinenwesen_, LIII
(1905, p. 450).
[8] This paper is published in pp. 148-166 of this book.
[9] Abstract from _Transactions_ of the Australasian Institute of
Mining Engineers, Vol. IX, Part 1.
[10] In the course of subsequent discussion Mr. Horwood stated that the
losses in roasting were 12½ per cent. in lead and probably about 5 per
cent. in silver. As compared to roasting in Ropp furnaces the loss in
lead was 5 to 6 per cent. greater, but the difference of loss in silver
was, he thought, not appreciable. Mr. Hibbard said that the Central
mine had obtained satisfactory results with masonry kilns.—EDITOR.
[11] Abstract of portion of a paper presented at the Mexican meeting
of the American Institute of Mining Engineers, under the title “The
Mechanical Feeding of Silver-Lead Blast Furnaces.” _Transactions_, Vol.
XXXII, pp. 353-395.
[12] Abstract of a paper (“The Mechanical Feeding of Silver-Lead Blast
Furnaces”) presented at the Mexican meeting of the American Institute
of Mining Engineers and published in the _Transactions_, Vol. XXXII.
For the first portion of this paper see the preceding article.
[13] Abstract of a paper in _Western Chemist and Metallurgist_, I, VII,
Aug., 1905.
[14] Much better work is being done at present, smelting the Western
zinc ores, and the residue contains about one-third of the above
figure, or 7.5 per cent. of zinc oxide. The high per cent. of ZnO left
in residue was mainly due to poor roasting.
[15] There was also considerable coke used of an inferior grade, made
from Kansas coal.
[16] Part of the ZnO in roasted matte came from being roasted in the
same furnace the zinc ore had been roasted in.
[17] There was less residue on the charges during this month, which
accounts for the larger tonnage with a lower blast.
[18] Translation of a paper read before the Naturwissenschaftlicher
Verein at Aachen, and published in _Metallurgie_, 1905, II, i, 1-6.
[19] 35 to 40 cm. = 13.78 to 15.75 in. = 8 to 9.12 oz. per sq. in.
[20] _Engineering and Mining Journal_, 1904, LXXVIII, p. 630; article
by Donald Clark; reprinted in this work, p. 144.
[21] Owner of the patents.—EDITOR.
[22] Abstract of a paper in _Metallurgie_, II, 18, Sept. 22, 1905, p.
433.
[23] This method is described further on in this book.
[24] Translated from _Metallurgie_, Vol. II, No. 19.
[25] British patent, No. 17,580, Jan. 30, 1902, “Improved process for
desulphurizing sulphide ores.”
[26] W. C. Roberts-Austen, “An Introduction to the Study of
Metallurgy,” London, 1902.
[27] A. Lodin, _Comptes rendus_, 1895, CXX, 1164-1167; _Berg. u.
Hüttenm. Ztg._, 1903, p. 63.
[28] _Comptes rendus_, loc. cit.
[29] Translated from the _Zeitschrift für das Berg.-Hütten-und
Salinenwesen im. preuss. Staate_, 1905, LIII, ii, pp. 219-230.
[30] Translated from the _Zeitschrift für das Berg.-Hütten-und
Salinenwesen im. preuss. Staate_, 1905, LIII, ii, pp. 219-230.
[31] The manufacture of sulphuric acid from these gases has now been
undertaken in Silesia on a working scale.—EDITOR.
[32] A paper presented before the American Institute of Mining
Engineers, July, 1906.
[33] _Engineering and Mining Journal_, Sept. 2, 1905.
[34] This term is inexact, because the hearths employed in the United
States are not strictly “Scotch hearths,” but they are commonly known
as such, wherefore my use of the term.
[35] Percentages of lead in Missouri practice are based on the wet
assay; among the silver-lead smelters of the West the fire assay is
still generally employed.
[36] This improvement did not originate at either Alton or
Collinsville. It had previously been in use at the works of the
Missouri Smelting Company at Cheltenham, St. Louis, but the idea
originated from the practice of the Picher Lead Company, of Joplin, Mo.
[37] This refers especially to the Savelsberg process.
[38] A. D. Carmichael, U. S. patent No. 705,904, July 29, 1902.
[39] _Metallurgie_, 1905, II, i, 1-6; _Engineering and Mining Journal_,
Sept. 2, 1905.
[40] _Metallurgie_, 1905, II, 19; _Engineering and Mining Journal_,
Jan. 27, 1906.
[41] _Metallurgie_, 1905, Sept. 22, 1905; _Engineering and Mining
Journal_, March 10, 1906.
[42] _Engineering and Mining Journal_, Oct. 21, 1905.
[43] Translated by W. R. Ingalls.
[44] As originally published the title of this article was
“Lead-Smelting without Fuel.” In this connection reference may well be
made to Hannay’s experiments and theories, _Transactions_ Institution
of Mining and Metallurgy, II, 188, and Huntington’s discussion,
_ibid._, p. 217.
[45] Excerpt from a paper, “Concrete in Mining and Metallurgical
Engineering,” _Transactions_ American Institute of Mining Engineers,
XXXV (1905), p. 60.
[46] A Discussion of the Paper by Henry W. Edwards, on “Concrete in
Mining and Metallurgical Engineering,” _Transactions_ of the American
Institute of Mining Engineers, XXXV.
[47] _Engineering News_, Nov 30, 1899, and U. S. Patent No. 665,250,
Jan. 1 1901.
[48] A discussion of the paper of Henry W. Edwards, on “Concrete in
Mining and Metallurgical Engineering,” _Transactions_ of the American
Institute of Mining Engineers, XXXV.
[49] Abstract from the _Journal_ of the Chemical, Metallurgical and
Mining Society of South Africa, May, 1903.
[50] Abstract of a paper in _Transactions_ American Institute of Mining
Engineers, XXXIV (1904), p. 175.
[51] Silver not given. This was the case, also, with the gold in the
bullion. The slimes contained 0.131 per cent. of gold, or 39.1 oz. per
ton.
[52] A constituent company of the American Smelting and Refining
Company.
[53] Translated from _Zeit. f. Berg.-Hütten.-und Salinenwesen im
preuss. Staate_, 1905, LIII, p. 433.
[54] Abstract from a paper in _Zeit. f. Berg.-Hütten-und Salinenwesen
im preuss. Staate_, 1905, LIII, p. 439.
[55] Translated from _Zeit. f. Berg.-Hütten.-und Salinenwesen im
preuss. Staate_, 1905, LIII, 490.
[56] Abstract from a paper in _Zeit. f. Berg.-Hütten-und Salinenwesen
im preuss. Staate_, 1905, p. 400.
[57] Abstract from a paper in _Zeit. f. Berg.-Hütten.-und Salinenwesen
im preuss. Staate_, 1905, p. 400.
[58] Abstract from an article in _Zeit. f. Berg.-Hütten.-und
Salinenwesen im preuss. Staate_, 1905, LIII, p. 444.
[59] Translated from _Oest. Zeit. f. Berg.-und Hüttenwesen_, 1905, p.
455.