IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT
Year: 1884

page_text: I, EDWARD WILLIAM HARDING of 17 Thornhill Terrace Bishop Wearmouth in
the County of Durham Manufacturer, do hereby declare the nature of my
invention for IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT, to
be as follows:-
The object of this Invention in the first instance aims especially at the treatment
of the Cement in the Kilns or Ovens so as to ensure the better calcination without
vitrifaction by facilitating the uniform conv yance of heat throughout the matters
in the Kilns or Ovens.
The heat applied to the Kilns or Ovens may be that from Gas or Gas Fuel,
sufficient atmospheric air being admitted simultaneously in a cold or heated state
to ensure combustion and by these means to reduce the quantity of Coke or Coal
consumed at the same time that the calcination is effected more rapidly and
completely.
The materials used according to my improvements in the manufacture of
Portland Cement, are generally mixed together in a dry state and when the
ingredients are Chalk and Clay I dispense with the Wash Mill and Backs, the
Chalk and Clay being deposited on Floors heated by Flues, or in a closed, or open
chambers, and the heat applied, as is hereafter described, by means of Gas, or a
Gas Fuel and this heat is so regulated as.to drive the moisture from the Chalk and
Clay quickly, without baking them or otherwise prejudicially interfering with
their chemical properties.
The Chalk and Clay is then mixed in suitable proportions and ground together,
or separately and in this powdered state they are intimately mixed with each
other in their dry state in a mixing Mill or Hopper. During the mixing I add a
small percentage of Resin or some other solid highly inflammable material.
I next pass the mixed powder el materials into a Pug Mill, or pan with edge
runners or into a Mortar Mill, or other equivalent mixing apparatus, where enough
water is added to make the mixture sufficiently plastic to be easily formed into
Bricks, or other shaped pieces, by a Brick making machine, or other suitable means.
The Bricks, or shaped pieces, will then be ready for the Kilns, or Ovens.
The Kilns, or Ovens, are then charged much as usual viz. first with Coke and
then Bricks, or shaped pieces, to be converted and then again Coke and so on
in series until the Kilns, or Ovens, are sufficiently filled.

page_text: The requisite heat may then be applied by means of Fuel in the form of Gas
being admitted, or injected, at as many points as may be found desirable.
It may be desirable to stack the Bricks or forms of the material in the Kilns or
Ovens leaving apertures or spaces so as to assist the even distribution of the heat
throughout in the process of calcination.
The Gas for fuel, may be produced from Oil, Resin or other suitable vegetable
or mineral substances adapted to give a cheap Gas and may be produced by a Gas
producer or Reverberatory Furnace or otherwise, but I find it most convenient to
manufacture or produce the Gas from Coal, or Shale, according to circumstances.
In districts where Coal is cheap and of a bituminous nature, I carbonize the Coal
in suitable Retorts which may take the form somewhat of gas retorts but the
luminosity of the Gas not being of importance, and whilst heat giving properties
are so, the Tar and Ammonia with the lighter Hydro Carbons may be condensed
out of the Gas before use and the Gas then conveyed to the Kilus or Ovens, the
Retorts for carbonizing the Coal may be heated by Gas, sufficient Atmospheric air,
cold or heated, being supplied in the Furnace, or Flues. The Floors for drying the
Chalk and Clay may also be heated by such Gas as is used for the Kilns, or Ovens,
or the drying Floors may be so arranged with relation to the Kilns as to be heated
by the waste heat therefrom, or by the Flue-heat from the Retorts used for
carbonizing the Coal.
I
It will generally be found in practise that the cost of the gas manufactured for
use in the Kilus, or ovens, in my improved process will be compensated for by the
value of the coke produced and the bye products.
The Ammoniacal Liqour may be utilized in making sulphate of Ammonia or for
other uses and the Coal Tar either sold, or part of it employed in place of the
Resin, or other highly inflammable material used in the mixing with the
ingredients in a powdered state.
The object of mixing a small percentage of Resin or other inflammable material
with the raw or uncalcined or unburned materials for making Portland Cement is
to facilitate the calcining of the Cement, or cement forming matters in the Kilus,
or Ovens, by its aiding to conduct the heat through the Bricks or pieces, thereby
assisting the egress of the steam generated from the Water contained in the Bricks,
or pieces.
This invention may also be applied in the manufacture of Portland Cement
from other materials than those before referred to.
In some cases the Resin or other highly imflammable material may be dispensed
with and in such instances it is advisable to reduce the thickness of the Bricks, or
pieces.
Among the advantages attendant on the employment of my improvements will
be found more regular calcination of the cement in Kilns or ovens, increased yeild
of good marketable Cement from the same quantity of raw materials; considerable
reduction of cost for labor, and improved quality of cement as regards facility for
being ground and cost of grinding arising from the reduction of the quantity of
vitrified matters.

page_text: I EDWARD WILLIAM HARDING of 17 Thornhill Terrace Bishop Wearmouth in
the County of Durham Manufacturer do hereby declare the nature of my invention
for IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The object of this invention aims firstly especially at the treatment of the
Cement in the Kilns or Ovens so as to ensure the better calcination thereof
without vitrifaction by facilitating the uniform conveyance of heat throughout
the matters in the Kilns or Ovens.
The heat applied to the Kilns or Ovens may be that from Gas or Gas Fuel,
sufficient air being admitted simultaneously in a cold or heated state to facilitate
and as far as is practicable to ensure perfect combustion and by such means to
reduce the quantity of Coke or Coal consumed in the ordinary way of burning
Cement mixtures with the advantage of a more perfect calcination, the effecting of
same more rapidly and completely, with the avoidance of vitrifaction.
The materials used, according to my improvements, in the manufacture of
Portland Cement are generally mixed together in a dry state and when these
ingredients that are so mixed are chalk and clay, I am enabled to dispense with the
"Wash Mill" or "Backs," the chalk and clay being deposited on floors, or in a closed
or open chamber, and the heat applied, as is hereafter described in the form of Gas,
or Gas Fuel such heat being so regulated as to drive out the moisture from the
chalk and clay quickly without baking them or otherwise prejudicially interfering
with their chemical properties.
The chalk and clay are then mixed in suitable proportions and ground together,
or this grinding may be separately effected and in this powdered state they are
intimately mixed with each other whilst in a dry state in a mixing mill or hopper.
During this mixing I add a small percentage of resin or of some other solid highly
inflammable material.
I next pass the mixed powdered materials into a Pug Mill or pan with edge
runners or into a mortar mill or other equivalent mixing apparatus wherein enough
water is added to make the mixture sufficiently plastic to be easily formed into
bricks or other pieces either by a brick moulding machine or otherwise.
The bricks or pieces to be treated are then ready for the kilns or ovens, which
are charged much as is usual that is to say with Coke and then bricks or other
forms or pieces to be converted and then again Coke and so on in series until the
Kilns or ovens are sufficiently filled.
Or the chalk and clay may be reduced together in their relative proportions in
a harrow wash mill or other suitable wash mill or reducer, with sufficient water
being added thereto to bring the whole to a thick liquid consistency which may
then be run into a cistern or other receptacle and afterwards passed through
horizontal burr stones or such like means employed adaptable for reducing the
whole into a well and intimately mixed liquid mass; the resin or other solid highly
inflammable material being added either in the wash mill together with the chalk
and clay, or the admixture of the resin or its equivalent may take place at a later
stage as found more convenient in practice.
This liquid mass is then conducted by channels or conduits or by pumping to
drying surfaces of suitable form, which may be oblong square or otherwise, on
diying floors or on to moveable surfaces capable of traversing the drying floors

page_text: or on to the drying floors direct. Such floors being heated by suitable flues
arched, rectangular or of other shape or by heat channels of any suitable form
disposed below or otherwise, or the whole or part of the required heat may be
caused to flow over the matters under treatment or amongst them.
The heat employed may be that derived from Gas or Gaseous fuel used
simultaneously with the waste heat or Gases from the Kilns.
The drying floors may be arched or covered over and be placed in communication
with the Kilns so as to receive the waste heat or Gases therefrom and this heat
or Gas passes over the liquid mass or slurry and is utilized to assist in drying the
same simultaneously with auxiliary heat in the form of Gas or Gas Fuel and it
will in practice be found most economical to arrange the drying floor or floors at
about on a level with the top of the of Kiln so as to enable the dried mass to be
transferred to the Kiln with as little expenditure of labor as possible with
consequent economy.
The dried slurry or mixture will then be transferred to the Kilns or Ovens
in layers alternately with Coke and subjected to a similar treatment as herein before
described.
The requisite auxiliary heat to the Kilns or Ovens may then be supplied by
means of fuel in the form of gas, admitted or injected at as many points as may
be found desirable either immediately the contents of the Kiln or Oven or Kilns or
Ovens have been ignited or are commencing to burn or calcine, or the Gas may be
applied at a somewhat later stage.
It is desirable so to stack the bricks or forms or pieces of the combined
materials in the Kilns or Ovens, as to leave suitable apertures or spaces in order
to aid even distribution of the heat throughout the whole mass in the process of
calcination.
Gas suitable for fuel as described may advantageously be produced by a suitable
producer or reverberatory furnace or other well known means of production, from
resin or other suitable vegetable or mineral substances or liquids adapted to give a
cheap gas, but in practice I have found it most convenient to obtain gas from coal
or shale according to circumstances hence accordingly in districts where coal is
either plentiful or can be obtained cheaply and is of a bituminous nature, I carbonize
it in suitable retorts similar to retorts used in ordinary Gas Works, but luminosity of
the Gas being unimportant and heat giving properties being paramount in importance,
the Tar and Ammonia with the lighter hydro carbons are generally condensed out
of the Gas before use and the Gas then is conveyed to the Kilns or Ovens and to
the drying floors.
The Retorts also may be heated by Gas sufficient air either cold or in a heated
state being supplied in the furnaces or flues and the contained Coal thereby
carbonized in such Retorts.
The floors required for drying the chalk and clay in the case of the ingredients
being mixed or associated in a dry state may also be heated by Gas such as is used
for heating the Kilns or Ovens or these drying floors may be so arranged with
relation to the Kilns as to be heated by the waste heat therefrom or by the flue
heat from the retorts for producing the Gas.
By carrying out the manufacture of Portland cement according to my invention
it will be found in practice generally that the value realized by the production of
coke and by the utilization of the bye products will compensate for the cost of
manufacture of the gas for use in the Kilns or ovens.
For instance the ammoniacal liquor can be utilized in making sulphate of
ammonia or for other uses and the coal tar produced may be sold or partly used in
place of the resin or other highly inflammable material for mixing with the
materials for the Portland cement in a powdered state.
The object of mixing a small percentage of Resin or other suitable highly
inflammable material with the raw or uncalcined or unburned materials which are
to be burned in the manufacture of Portland cement is to facilitate the calcination
of such cement forming matters in the Kilns or Ovens by reason of such fuel in its

page_text: combustion aiding to conduct the heat throughout the substance of the bricks or
other pieces whereby egress of the steam or vapor generated is facilitated therefrom
without inconvenient or injurious splitting or rending.
The invention is applicable to the manufacture of Portland Cement from materials
other than those more particularly referred to.
In some cases the use of the Resin or other highly inflammable material may be
dispensed with, in which event the thickness of the bricks or pieces will generally
need to be lessened.
Among the advantages attendant upon the use of my invention will be found
that more regular calcination of cement in the Kilns or ovens is secured, with an
increased yield in good marketable cement from the same quality of raw material
whilst the facility with which such cement can be ground will be much enhanced
thereby reducing cost of grinding, owing to the diminished amount of vitrified
matters and generally considerable saving in cost for labour accrues.
Having now particularly described and ascertained the nature of my said.
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1st The introduction of Gas, in Kilns used in the manufacture of Portland
Cement obtained as set forth in the foregoing specification, whereby a more perfect
calcination is obtained.
2nd The utilization of the waste heat in the carbonization of Coal or other
substances for producing the Coke or Fuel required in Portland Cement making as
set forth.
3rd The heating of the drying floors used in the manufacture of Portland Cement
by auxiliary heat simultaneously with the admission of waste heat over or amongst
the slurry or pieces of mixtures for producing Cement as set forth.
4th The introduction of Resin or other solid inflammable material for conveying
heat more readily throughout the Cement mixtures during calcination as set forth.
5th The combining of the processes for carbonizing Coal with those for Cement
making purposes whereby the waste heat or Gases are utilized substantially as set
forth.
6th The arrangement or combination of drying floors, either open or covered,
with or without underneath flues, with Cement burning Kilus substantially as set
forth.