Improvements in the Reduction of Ores, and Obtaining the Metal therefrom by the Utilization of Waste Gases from Carbonization of Vegetable Matter.
Year: 1885

page_text: Improvements in the Reduction of Ores, and Obtaining the
Metal therefrom by the Utilization of Waste Gases from
Carbonization of Vegetable Matter.
I ALFRED JULIUS BOULT of 323 High Holborn in the county of Middlesex,
Engineer, do hereby declare the nature of this invention (a communication from
Henry M. Pierce of Nashville, Tennessee, United States, Manufacturer) and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The present invention relates to the utilization of certain waste gases, to wit:
the non-condensable gases evolved in the distillation and carbonization of wood
for metallurgical purposes, whereby a chemically pure heat is produced, and
whereby a metal of better quality is obtained.
For the purposes of this description, I have seen fit to describe it in conjunction
with other fuel in a blast furnace or smelting process. In which process it is
necessary to use other fuel, such as charcoal, coke or other solid fuel in order to
prevent scaffolding, to preserve in a measure the permeability of the mass and to
supply a deoxidizer, and a carburizer. Though it is evident that in the puddling
furnace, and in the heating and melting of metals where the physical conditions
required are different, these gases may be used either in combination with other
gases, or independently as a fuel, and the same valuable results due to its chemical
purity will be correspondingly obtained.
To put into practical operation this invention, I employ an ordinary charcoal,
pig-iron blast furnace provided with suitable air and gas inlets, and combine
therewith gas and air heating chambers. The gases are generated in wood
carbonizing kilns or ovens, from which, they are withdrawn and passed through
condensers. From these condensers, the uncondensable gases are withdrawn and
projected into the furnace through an ordinary equalizer and hot blast chamber.
Heretofore in ordinary practice, the blast furnace has been supplied at regular
intervals with charcoal, ore and a flux in proper proportions-sufficient charcoal
being used to generate the heat required to reduce the ore to metal.

page_text: A furnace similar in general construction to the ordinary blast furnace is
employed. The furnace is charged in the usual manner with the same proportionate
amounts of ore and flux as would be used were charcoal the sole fuel.
The amount
of charcoal however, charged at the same time with the ore and flux is graduated
to supplement the fuel furnished in the wood gases.
These gases are injected either warm or cold into the blast furnace in or above
the air tuyere zone. In the furnace they mix with the hot or cold air blast and
are consumed. The combustion of these gases and of the charcoal distributed
throughout the charge, furnishes heat sufficient to carry on the ore reducing
process; it is found in practice that 60% of these gases, to 40% of the solid fuel
heretofore used is efficient.
The value and importance of this gaseous fuel, as applied to metallurgical
purposes, and the extent to which it may lessen the use of charcoal, in a blast
furnace may perhaps be more fully appreciated by noting the following facts.
A cord of wood seasoned, weighs, say 4000 lbs. In reducing this cord of wood to
charcoal, of charcoal by weight, say, 1000 lbs. are obtained, or one quarter of the
entire weight of the wood. The remaining 3000 lbs. pass off in the form of gases.
These gases are largely hydro-carbons which properly prepared and managed, are
capable of generating a large amount of heat, indeed, about 1000 of the 3000 lbs.
of the gases thrown off from each cord of wood reduced to charcoal are fixed
hydro-carbon gases, capable of producing, when mixed with the air, a chemically
pure flame free from all injurious elements.
A cord of wood will throw off, in being reduced to charcoal, about 28,000 cubic
feet of gas. The ordinary charcoal furnace requires about 100 cords of wood daily
for charcoal purposes. One hundred cords of wood properly charred, will deliver
at any reasonable distance from the coaling oven 700,000 cubic feet, or 50 tons of
uncondensable gases; hence, 100 cords of wood will yield in weight as much fuel
in form of gas as in form of charcoal. By utilizing the fixed gases thrown off in
making charcoal, the amount of fuel produced by wood is at least doubled. In
addition to this, gas fuel is free from ash and all injurious matter and is easier
converted to heat than charcoal or any other fuel,
The wood gases are valuable, first for their heat producing power;
and secondly,
because being a gaseous fuel, they are more cheaply and easily introduced, into a
furnace and there converted into heat, than a corresponding weight of the fixed
fuels, and finally, being chemically pure produce a better quality of iron. Hence,
the employment of wood gases as a fuel, in blast furnaces, in combination with
more or less fixed fuels, first, converts to a profitable use valuable bydro-carbon
gases now generally allowed to go to waste; secondly, gives to the furnace-man in
charge, absolute control of the temperature of the furnace; and thirdly, cheapens
the production of the metal by lessening the amount of charcoal now essential to
its manufacture. Indeed the utilization of these wood gases is an economic
necessity in order to obtain full value of wood that is now daily becoming more
scarce, and higher priced.
This process can be employed with a corresponding economy of fixed fuel in the
reduction of valuable ores for any metal such as gold, silver, etc.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as, communicated to
me by my foreign correspondent I declare that what I claim is
.
1. The process herein described for the heating and smelting of ores and metals,
which consists in subjecting the same to the heat produced by combining air with
non-condensable gases derived from the distillation or carbonization of wood or
other vegetable matter, substantially as and for the purpose set forth.
2. The process herein described for the reduction of ores and metals which
consists in subjecting the ore, flux and a percentage of solid fuel sufficient to
supplement the gaseous fuel to the heat produced by combining air with heated

page_text: non-condensable gases derived from the distillation or carbonization of wood or
other vegetable matter, substantially as set forth.
3. In a blast furnace, the process herein described of utilizing the gases evolved
in the destructive distillation of wood or other vegetable matter as fuel which
consists in first conducting the said gases from the carbonizing chamber, to a
condenser, and reducing to liquid their condensable constituents; then forcing the
uncondensable gases through a heating chamber which is heated by the waste gases
from the said blast furnace; and finally with a suitable quantity of atmospheric air
injecting them into a blast furnace.
4. The process herein described of utilizing the gases evolved from the destructive
distillation of vegetable matter, which consists in conducting the said gases into a
condenser, then forcing the non-condensed gases under pressure into an equalizing
chamber, then through a heated chamber which latter is heated by the waste gases
from the blast furnace, and finally, with the proper quantity of atmospheric air
forcing them into the blast furnace, as described.