Improvements in or relating to the Calcination of Limestone, Ironstone, or the like Substances.
Year: 1892

page_text: Date of Application, 17th Feb., 1892
Complete Specification Left, 17th Dec., 1892-Accepted, 11th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Calcination of Limestone,
Ironstone, or the like Substances.
1, CHARLES RUDOLPH COWENS, of Trimdon Grange, R.S.O. in the County of
Durham, Quarry Owner, do hereby declare the nature of this invention to be as
follows:-
My invention relates to improvements in the process of and apparatus for
calcining limestone, ironstone, or the like substances, and in the recovery and
utilization of bye products and residuals for commercial purposes.
As my invention will be principally applied to the calcination of limestone, I will
for simplicity of description refer to this material only.
The usual mode of calcining limestone is to charge the limestone into a kiln
sandwiched between layers of coal, coke, or the like combustible materials, the
combustion of which effects the calcination of the limestone.
The lime resulting from this expensive process is liable to be mixed with cinders
or residual matter from the fuel which is detrimental to its quality.
The object of my invention is to dispense with coal, coke, or fuel of the like
commercial value and to effect the calcination of the limestone by the application
of heat derived from the combustion of gases obtained at a cheap rate from any
materials of small commercial value which are suitable for the purpose, that is
which contain the requisite proportion of hydrocarbons and fixed carbons such as
inferior coal, bituminous shale, town ashpit or the like refuse, or other similar
materials which are subjected to the well known process of partial and slow
combustion and to the injection of steam through and over the glowing mass.
When the gases from the producer are sufficiently rich in ammonia and other
useful bye products they are cooled and washed in any suitable manner, and are
then passed direct into the lower part of the kiln where their combustion caused by
the admission of the requisite quantity of air produces a temperature sufficient to
liberate and expel the carbonic acid from the limestone which is carried off with
the products of combustion. The lime resulting from the above described process
is of superior quality due to the limestone not having been brought into contact
with the impurities or residuals of the fuel.
A simple mode of carrying my invention into effect consists as follows:-1
construct a close furnace or producer of any suitable dimensions which I furnish
with a shoot or hopper at the upper part, and suitable arrangements for removing
cinders and ashes, and for admitting steam and air at the lower part. The producer
communicates with the kiln direct, or if bye products are to be recovered the gases
from the producer are passed through condensers and washers and then into the
kiln, the connection being from the upper part of the producer to the lower part of
the kiln where the combustion takes place.
1000

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to the Calcination of Limestone,
Ironstone, or the like Substances.
I, CHARLES RUDOLPH COWENS, of Trimdon Grange, R.S.O. in the County of
Durham, Quarry Owner, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention relates to the process of and apparatus for calcining limestone,
ironstone or the like substances, more especially dolomite.
As an important use of my invention will be its application to the calcination of
limestone, I will for simplicity of description refer to this material as representing
generally materials for the calcination of which my invention is similarly
applicable.
The usual mode of calcining limestone is to charge the limestone into a kiln
sandwiched between layers of coal, coke and the like combustible materials, the
combustion of which effects the calcination of the limestone. The lime resulting
from this expensive process is liable to be mixed with cinders or residual matter
derived from contact with the fuel and which is detrimental to its quality.
By means of my invention I am able to dispense with coal, coke, or fuel of the
like commercial value and to effect the calcination of the limestone by the
application of heat derived from the combustion of gases, which may be obtained
at a cheap rate from any materials of a lower commercial value which are suitable
for the purpose, that is, which contain the requisite proportion of hydro-carbons
and fixed carbons, such as inferior coal, bituminous shale, town ash-pit or the like
refuse, or other similar materials which are subjected to the well known process of
partial and slow combustion and to the injection of steam through and over the
glowing mass. But so far as the invention described in my Provisional Specification
extends to the recovery and utilization of byc-products and residuals for commercial
purposes, I have since found that there is some doubt as to the practical advantage
and utility of attaching condensers, washers or the like appliances to the apparatus
hereinafter described to be brought into operation in combination with the process
of calcination.
I therefore omit any description of suitable means for effecting this purpose
a combination with the improved apparatus and process constituting my invention.
But in order that my invention may be clearly understood and readily carried
into effect, I will now proceed to describe the same by referring to the accompanying
drawing in which an apparatus adapted for the purposes of my invention is
illustrated by way of example.
In the apparatus A is a producer communicating by flues with a kiln B; to these
may be added if preferred a regenerator C, so that the heat carried off with the
waste products of combustion as they leave the kiln are received into the
regenerator and so utilized in raising the temperature of the air supplied to
the kiln B, which air is also further raised in temperature by passing through the
chamber D, which serves as a temporary receptacle for the lime which drops down
into it in a highly heated state from the calcining kiln B.
b
The several parts of the apparatus being constructed and arranged as shown in
the drawing they are intended to carry out the process of calcining the limestone
in the following manner. A mixture of air and steam is caused to enter into the
pipera, to be discharged therefrom immediately below the grating 6 through which it
enters the producer A, and diffuses itself through and over the mass of material
which is charged therein as fuel setting up a slow and partial combustion the
products of which are delivered along the flues or passages C, into the kiln B. In
combination with these combustible gases air is admitted into the air dome d, and
through the chamber D, where it encounters a mass of hot lime which at the

page_text: commencement was heated by coke and is thereby materially raised in temperature
as it penetrates its way through to the kiln B. The mixture of this air with the
gases from the producer A sets up the requisite combustion within the kiln B to
liberate and expel the carbonic acid from the limestone which is carried off with
the waste products of combustion.
An important feature of the above described process is that the limestone is
never in contact with the fuel and the lime resulting therefrom is consequently of
superior quality due to the absence of any mixture of the impurities or residuals
of the fuel. In order to utilize the heat of the waste products of combustion the
regenerator C may be suitably constructed in various ways as for instance by
conducting the waste products of combustion from under a dome E, into a system
of flues e, from which it is drawn into the chimney. Air enters another system of
flues, and is finally delivered through the passage g, into the air dome d. I have
not considered it necessary to further describe a suitable construction of regenerator
in detail as regenerators have been adapted for many purposes and are now well
understood.
The apparatus can be worked at various temperatures according to the nature of
the process in hand, a damper h, and other suitable and well known appliances
being provided as required. As for instance a moderate temperature only is
required for expelling carbonic acid from limestone, whilst a high temperature is
required for the similar process of reducing dolomite to its maximum density.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be perforined, I declare that what I
claim is :-
Firstly-In the process of calcining limestone, ironstone, or the like materials,
the use of an apparatus in which the calcination is effected by means of combustible
gases supplied from a producer, combining within the kiln with air which has been
raised in temperature by absorbing heat from the calcined material with or without
previous heating in a regenerator, forming part of the apparatus, all combined and
operating together substantially as and for the purpose as herein before described
with reference to the accompanying drawing.
Secondly-In the process of calcining limestone, the use of an apparatus
arranged and constructed substantially as and for the purpose as hereinbefore
described and illustrated.
Dated this 16th day of December 1892.