New or Improved Process and Apparatus for Reducing or Smelting Ores.
Year: 1895

page_text: Date of Application, 7th May, 1895-Accepted, 29th June, 1895
COD DRIV DT DUIFICATION,
New or Improved Process and Apparatus for Reducing or
Smelting Ores.
1, EMIL ERNST LUNGWITZ, of No. 842 Bushwick Avenue, in the City of
Brooklyn, County of Kings and State of New York, United States of America,
Mining Engineer, do hereby declare the nature of this invention, and in what
mauner the same is to be performed, to be particularly described in and by the
following statement
The present invention relates to an improved process of smelting ores, and it has
for its object to prevent the loss of metals by volatilization.
It is well known that the boiling point of a substance depends upon the pressure
exerted upon the liquid, the boiling point rising with the pressure according to a
law governed by the nature of the substance. Sufficient pressure will prevent
ebullition of a liquid, even if its temperature be raised considerably beyond its
boiling point under ordinary pressure To prevent volatilization of the regulus once
formed, it is only necessary to maintain a sufficiently high pressure in the furnace.
In the case of an ore contaming lead and zinc oxides, for instance, the zinc would
volatilize at the temperature of the furnace, say 1200° C., if a sufficient prossure
were not exerted to raise its boiling point to this temperature.
From the
researches of Dr. Carl Barus (Bulletin U.S. Geological Survey No. 54, 1889, and
confirmed by my own investigation), we may conclude that the tension of zinc
vapor at this temperature would be about 50 lbs.
A represents the steel or similar casing of the stack supporting and enclosing
the fire brick B. The throat of the furnace is closed by a cap or plate C having
an opening controlled by a trap-door Chinged to the under sule of the cap. This
opening is preferably centrally located, but may be placed toward the side of the
throat if desired. The usual hopper D for feeding ore and fuel is inserted in the
throat of the furnace. The discharge opening in this hopper is controlled by a
trap doo D' hinged to the under side of the hopper. The trap doors C and D
may, if desned, be replaced by ordinary bell closures. Tuyetes E of the usual
construction supply the blast for raising the temperature, and also for raising tho
pressure within the furnace so that the reduced metal or oxides will not boil under
the temperature necessary for conducting the process. F is a second steel or other
casing surrounding the casing A. The space between these two casings forms a
water and air-tight chamber which water is kept circulating to cool the casing A,
and to prevent injury to said casing, if it should become exposed to the pressuro
within the furnace through fusing of the bick at any point, the water in said
chamber is kept under pressme equal to the pressure within the furnace. Water
is supplied to this cooling chamber, through the nozzles of the pipes G leading
from the bustle pipe G by any suitable pump the water entering preferably near
the throat of the furnace and descending to the hearth, thus cooling the upper
portion of the stack fist, and being heated gradually as it approaches the hearth,
where it escapes through a suitable discharge pipe G¹. This hot water may be
utilized by feeding it directly to the boiler connected with the engine supplying
the blast for the furnace. Suitable pressure gauges I and II' are applied to the
furnace to indicate the pres-unes excited within the furnace and the cooling
chamber respectively, in order that said pressures may be kept equal. Safety

page_text: The
valves and may also be applied to the furnace and the cooling chamber
respectively, to balance the pressures by removing any excess in either
furnace safety valve I is preferably located just below the trap door D', and
through it the waste gases are discharged. The construction of this valve 18
similar to that of a boiler safety valve.
The operation of my invention is as follows.
A charge of fuel and orc is introduced into the furnace through the openings in
the plate C and hopper D after which the trap doors C and D' are closed. After
the fires are stated the blast is turned on through the tuyeres E until the pressure
within the furnace exceeds the pressure at which the metal to be reduced would
bol at the temperature to be created by the blast As soon as the one is smelted
the reduced metal sinks to the hearth, where it collects and may be drawn off
though the tap hole. Volatilization of the metal on regulus and of the oxides 15
thus prevented, as the pressure oxerted upon the charge is so high that it cannot
boil, and hence cannot volatilize and be carried off through the furnace throat, or
over into the fluo dust chamber. This is a feature of great importance as the
metal once reduced sinks to the hoarth, and is not carried off by the flue to be
returned through the hopper in the form of an oxide and resmelted. Besides, by
the expansion of the blast in furnaces as at present constructed, the finer particles
of the charge are carried over into the flue dust chamber, as the blast maintains its
pressure only at the tuyeres. As any desired pressure 13 maintained constant
thoughout the furnace in my invention, however, the formation of fluc dust is
almost entirely prevented.
The construction of furnace I have illustrated is especially designed for
continuous smelting and roasting without lowering the pressure within the furnace.
When it becomes necessary to recharge the furnace the trap door C¹ (or bell as
the case may be) 1s opened, and fuel or ose fed into the hopper, the trap door D'
(or bell) being kupt closed. When a sufficient quantity of the charge las thus
been introduced into the hopper the door C is closed and D' is opened, when the
fuel or ore enters the fminace, the door D' being closed after all the charge has
been fed, to the furnace by the hopper. It will be seen that while thus recharging
the furnace one of its gaseous contents can escape, and the pressure remains
undisturbed, as one of the exits is always closed and the enclosed gases cannot get
beyond the cap plate C of the stack.
My process is applicable not only to the smelting and roasting of ores containing
a single metallic element, but to ores containing several such elements. The
pressure of the blast would of course depend upon the metal or metals to be
reduced and to be oxidized from the ore, and where several metals are reduced and
Toasted simultaneously within the furnace the pressure would be sufficiently bigh
to prevent volatilization of the metal to be tapped.
do not wish to be understood as limiting myself to any specific means for
regulating and balancing the pressures in the furnace and cooling chamber
respectively as the means so employed may be modified without departing from the
spirit of the invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim 18:
1. The process of reducing ores containing as a constituent a volatılizable
metallic element which consists in melting the ore and maintaining within the
furnace a pressure higher than the piesame at which the resulting metal or
regulus or one of its constituents would boil at the temperature obtaining in the
fuinace, substantially as described.
2. The heren described blast furnace stack closed to the atmosphere, means for
maintaining within the stack a pressure higher than that at which the metal would
boil at the temperature of the furnace, a closed casing surrounding said stack and

page_text: forming with its exterior walls an air-tight chamber, and means for exerting and
maintaining in said chamber a pressure substantially equal to the pressure
maintained within the stack, as described.
1
LOOK
E. E. LUNGWITZ,
Per W. H. Beck,
115 Cannon Street, London, Agent.
E. E. LUNGWITZ,
Per W. H. Beck,
115 Cannon Street, London, Agent.