IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT
Year: 1883

page_text: LETTERS PATENT to John Henry Johnson, of 47 Lincolns Inn Fields in the,
County of Middlesex Gentleman for an Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF PORTLAND CEMENT"-communicated to him from Edward
J. De Smedt a person resident at Washington City; District of Columbia, and
Robert W. Lesley a person resident at Philadelphia, Pennsylvania, in the
United States of America
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the,
Office of the Commissioners of Patents on the 20th March 1883.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT"-a.
communication to me from Edward J. De. Smedt a person resident at Washington
City, District of Columbia and Robert. W. Lesley a person resident at Philadelphia
Pennsylvania in the United States of America
The object of this Invention is firstly to produce in a moist state bricks or pieces.
of the materials from which portland Cement is made, the said bricks or blocks of
a sufficient porosity to allow the water of evaporation to escape during the calcining.
operation without breaking the bricks into pieces or dust and thus to overcome.
many of the objections difficulties and expenses incidental to this manufacture as
at present conducted
My foreign Correspondents have found that this result can be obtained by mixing.
a combustible by preference a hydro-carbon with the argills-calcareous or argillo-,
magnesian material prior to the calcining operation and it is this feature that
characterizes this part of the present invention
It is preferred to use a hydro-carbon combustible and among the hydro-carbons
coal, tar, petroleum oil or petroleum residuum are preferred I do not however
restrict myself to hydro-carbons as any combustible may be used for instance.
sawdust, should the material be of such character as to require an addition of
potash. Preferably about five parts by weight of the combustible are used to one
hundred parts of the dry.powder from which the paste is made, but I do not confine.

page_text: myself to this per centage for the proportions may be considerably varied without
departing from the nature of the Invention
It will be found preferable to mix the combustible with the dry powder and then
to mix the mass with water sufficient to make a thick paste. The mixing can be
effected in any suitable way and by the aid of ordinary mixing apparatus but the
combustible, the powder and the water may be mixed together at one and the same
time if desired
Under some circumstances it may be advisable to mix the powder and the
combustible in beated state but as a general rule this will not be found necessary
The paste thus produced is made up in the usual way into bricks or other forms
which in their moist state are put into the kiln and subjected to the calcining.
operation
They can be taken at once from the mill or place where they are formed and
put into the kiln no delay being necessary During the calcining operation the
combustible contained in the brick burns out, gradually and the brick is thus
rendered porous little by little according to the penetration of the combustion
The steam or vapour. has thus afforded to it a free passage from the brick and
the latter preserves its form and shape unimpaired throughout the process of
calcination. There is a noticable absence of the surface glaze or vitrefaction
which usually appears on the calcined brick under ordinary methods, and besides
this the calcination is more uniform and regular by reason of the introduction
throughout the brick of a heat giving combustible
The bricks or forms. after calcination are ground, and the product may be packed
in barrels in the usual way. The invention possesses the following advantages over
the methods of manufacture heretofore practiced
As compared with the "wet" system it' does away with the "backs" or vats
and the necessity for acres of storage room it lessens the amount of handling
required because it permits the paste to be run directly from the mixers to the
kilns, it prevents the irregularity in the paste which results in the "wet" system
from the settling of the heavier portions, and it lessens the outlay of capital
required to carry the paste for months before it is ready for use
As compared with the " dry" process it reduces the ordinary handling about
one third, it does away with drying floors, and it also does away with all the
expense for fuel now required' to dry the paste
As compared with both systems it reduces the time required for manufacture
from months in the "wet" system and, weeks in the "dry" system, to two or
three days, it reduces to the minimum all loss by waste and powdering in the kilns,
it reduces cost of grinding owing to the absence of the usual surface glaze or
vitrefaction on the brick, it reduces the amount of fuel required to calcine the
bricks, and it insures a regular and uniform product
The invention is applicable generally to all hydraulic cements in which the
material is reduced to the condition of a paste before calcination
My foreign Correspondents have further ascertained that argillo-manganesian and
argillo-calcareous Cement rocks and hydraulic limestones are adapted in other
respects to this manufacture they are deficient for that purpose in the amount of
lime they contain. And they have discovered that by combining with them lime
in sufficient quantity to bring the percentage of this ingredient in the compound
up to about 70 per cent.this difficulty is completely obviated and a cement can be
produced having all the characteristics and qualities of the best Portland. Cement
By this Invention a more regular accurate and better Portland Cement can be
produced than by the methods now in use and a very considerable saving in money
and labour is effected
One way in which the invention may be carried into practical effect is as
follows
The cement rocks or the hydraulic limestone or both are taken and ground up
raw. By analysis it is ascertained what is the chemical composition of the ground
mass with a view to determine the extent to which it is deficient in lime and then

page_text: there is added to the mass lime in such proportion as to make the manufactured
Portland Cement analyze about 70 per cent (or say from 55 or 60 to 70 per Cent)
of lime or lime and magnesia
After the addition and incorporation of the lime the powdered or ground mass
is moistened made into bricks or other forms dried, calcined to a clinker and ground
into cement under either the "wet" process or the "dry" process as preferred. Or
if desired it may be made into Cement in accordance with the process herein before
first described consisting in the mixture with the Cement paste before calcination
of a hydro-carbon or other combustible
I have stated that the ingredient added to the ground rock is lime-Under the
term lime I desire to be understood as including lime or dolomite lime which
will slake in water either hydrated or anhydrous or in the form of a carbonate
which after calcination will slake in water Portland Cement can also be made
from ordinary natural Cements such as Rosendale Cement and Cumberland Cement
by adding to them lime in the proportion hereinbefore indicated and then moistening
the mass, making it into bricks or other forms, recalcining the same to clinker, and
then grinding the calcined product
Portland Cement may also be from the ordinary natural Cements, by first
recalcining the latter to clinkers and then regrinding and adding lime in the
proportions hereinbefore indicated

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
20th September 1883.
"
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman IMPROVEMENTS IN THE MANUFACTURE OF PORTLAND CEMENT
a communication to me from Edward J de Smedt a person resident at Washington
City District of Columbia and Robert W Lesley a person resident at Philadelphia
Pennsylvania in the United States of America
In order that the present Invention may be more readily understood I will first
set out the usual methods of manufacturing Portland Cement and the disadvantages
attending them and will then describe the improvements on the same according to
the present Invention.
Portland cement is a compound of argillo-calcareous or argillo-magnesian
substance, and may be made from natural rocks or earths wherein are found by
analysis the necessary proportion of Silica alumina and lime or magnesia or from a
combination or mixture of lime with clay of various kinds.
"
"
It is usually made in two ways known as the "Wet" or "English" process and
the "Dry
"
or German" process.
First, The "Wet" process. In this process clay and chalk in proper proportions
are thrown into a pug mill or into a mill with chasers, and water is added; the
mixture is constantly stirred and the chasers reduce the "mix to an almost
impalpable powder causing perfect admixture. The mixture is then allowed to
flow out in a paste of about the consistency of cream on to drying floors heated by
Steam for the purpose of expelling the excess of water by artificial heat or into
" backs ΟΙ "vats" in the open air about two feet deep where by evaporation and
decantation all the water is drawn out.
»
The paste thus formed is (when dry) cut into bricks or Squares and carried to
the kilns.
When placed in the kilns many of the pieces lose their corners and much of the
dry material is scaled off by reason of the intense heat and the powder thus formed
owing to its not being properly calcined and to its becoming mixed with the dust
of the ashes is wasted. When drawn from the kilns the material is in form of
clinker, in masses as large as a man's head and in most cases covered with an
impenetrable vitrification or glaze which is injurious to the manufacture of cement
and makes the grinding very difficult.
The clinker drawn from the kilus is carefully examined, all vitrified pieces
thrown out, the underburnt portion put in again and the good clinker broken up in
breakers and then ground and packed in barrels ready for market.
Second. The "Dry" process. In this process the chalk and clay having been'
dried and powdered are mixed together in a dry mixer in a dry state and are then
run into a pug mill where just enough water is added to make a stiff paste. The
material as it exudes from the pug mill is cut into bricks loaded on to cars and
carried to a drying room where in about a week or two weeks' time it is ready to
be carried to the kilns.
It is then burned, as in the other process before described, ground and barrelled.
The same disadvantages of "burning" apply to this dry process as have been
described as applying to the "wet" process.
Disadvantages of the "Wet" System.
This System has the following disadvantages.
a. The immense storage room required for the wet paste.
b. The repeated handling required.

page_text: c. Ine irregularity of the inanufactured article, the paste run out into the "backs
being composed of materials of different specific gravities, the heavier naturally
settling to the bottom.
d. The large capital required to carry the Stock of paste in the "backs," the
material requiring from two to four months to dry.
Disadvantages of the "Dry" System.
a. It requires one or more handling and one more grinding than the "Wet."
b. The large expense for drying floors:
c. The large expense for fuel required in the drying operation.
Disadvantages incidental to both Systems.
1. The handling of the material from the mixers to drying floors or "backs" and
then back to kilns.
2. The waste of time and money before the mixed material can be used.
3. The loss by wastage in the kilns as before described.
4. The added difficulty of grinding the glazed clinker.
5. The extra amount of Coal required to send heat through the Cold or only
partly warmed masses of dried paste.
It will be noticed that most if not all of these disadvantages are due directly or
indirectly to the preliminary drying operation which is performed before the
calcining operation can take place.
'
Ordinary paste formed into bricks or other forms if subjected in the moist state.
to a great heat will fly apart and will all scale off into powder leaving nothing"
beliind and consequently proper calcination is impossible. This effect is due to the.
sudden evaporation of the water contained in the bricks or pieces. The water in
its course towards evaporation encountering an obstacle (the coating formed on the
outside of the brick) breaks it in order to escape. This scaling off goes on
continually until the whole piece is reduced to powder. Thus it is that recourse
is had to the method now in use of thoroughly drying the paste before calcining it,
a process of great length and most expensive.
The object of the present Invention is to produce in a moist state bricks or blocks
of the materials from which Portland cement is made, the said bricks or blocks.
being of a sufficient porosity to allow the water of evaporation to escape during the.
calcining operation without breaking the bricks into pieces or dust and thus to
overcome many of the objections difficulties and expenses incidental to this
manufacture as at present conducted.
My Foreign Correspondents have found that this result can be obtained by
mixing a liquid combustible, by preference a hydro-carbon with the argills-
calcareous or argillo-magnesian material prior to the calcining operation and it is
this feature that characterizes the present Invention.
It is preferred to use a hydro-carbon combustible and among the hydro-carbons,
Coal tar, petroleum, petroleum oil or petroleum residuum are preferred.
I do not however restrict myself to hydro-carbons as any other liquid combustible,
may be used, such as vegetable or animal Oils. Preferably about five parts by
weight of the combustible are used to one hundred parts of the dry powder from
which the paste is made; but I do not confine myself to this percentage for the
proportions may be considerably varied without departure from the nature of the
Invention.
It will be found preferable to mix the liquid combustible with the dry powder
and then to mix this mass with water sufficient to make a thick paste. The mixing
can be effected in any suitable way and by the aid of ordinary mixing apparatus,
but the combustible, the powder and the water may be mixed together at one and,
the same time if desired.
Under some circumstances it may be advisable to mix the powder and the
combustible in a heated state but as a general rule this will not be found necessary.
The paste thus produced is made up in the usual way into bricks or other forms
which in their moist state are put into the kiln and subjected to the calcining
operation.

page_text: They can be taken at once from the mill or place where they are formed and put
into the kiln, no delay being necessary. During the calcining operation the liquid
combustible contained in the brick burns out gradually and the brick is thus
rendered porous little by little according to the penetration of the combustion.
4
The Steam or vapour has thus afforded to it a free passage from the brick and
the latter preserves its form and' shape unimpaired throughout the process of
calcination. There is a noticeable absence of the surface glaze or vitrefaction which
usually appears on the calcined brick under ordinary methods and besides this the
calcination is more uniform and regular by reason of the introduction throughout
the brick of a heat giving liquid combustible.
The bricks or forms, after calcination, are ground and the product may be packed
in barrels in the usual way. The Invention possesses the following advantages
over the methods of manufacture heretofore practised.
As compared with the "wet" system it does away with the "
"backs " or vats
and the necessity for a great extent of storage room; it lessens the amount of
handling required because it permits the paste to be run directly from the mixers
to the kilns; prevents the irregularity in the paste which results in the "Wet"
System from the settling of the heavier portions and it lessens the outlay of capital
required to carry the paste for months before it is ready for use
As compared with the "dry" process it reduces the ordinary handling about one
third, it does away with drying floors and it also does away with all the expense
for fuel now required to dry the paste
As compared with both systems it reduces the time required for manufacture
from months in the "wet" system and weeks in the "dry" system to two or three
days it reduces to the minimum all loss by waste and powdering in the kilns it
reduces cost of grinding owing to the absence of the usual surface glaze or
vitrifaction on the brick it reduces the amount of fuel required to calcine the
bricks and it insures a regular and uniform product
The part of the Invention hereinbefore described is applicable generally to all
hydraulic cements in which the material is reduced to the condition of a paste
before calcination
"
The Invention further consists as follows. Portland Cement in rare instances is
made from natural rocks wherein have been found the requisite ingredients combined
in proper proportions but usually it is manufactured from chalk and clay by the
"
wet process or the "dry" process both of which processes of manufacture are
well known to those skilled in this industry the manufactured article by chemical
analysis ordinarily containing about thirty per cent of silica and alumina and
Seventy per cent of lime and magnesia together with small and varying per centages
of oxide of iron potash sulphuric acid and other matters
In places where there is a difficulty in finding clay and chalk or carbonate of lime
containing the proper ingredients in proper form in such proximity to one another
as to admit of economical working the processes as hitherto attempted have not
been attended with pecuniary success
In such places however Argillo-magnesian and argillo calcareous cement rocks
and hydraulic lime stones may be found quite abundantly and have been used
extensively for the manufacture of cement But although containing silica, alumina,
magnesia, and lime and other ingredients they are ineffective in themselves to
produce Portland Cement the Cement made froin them being common cenient such
for instance as the cement known in the market as Cumberland cement Rosendale
cement and the like
My foreign correspondents have found that whilst these rocks are adapted in
other respects to this manufacture they are deficient for that purpose in the amount
of lime they contain and they have discovered by experiment that by combining
with them lime in sufficient quantity to bring the percentage of this ingredient in'
the compound up to about Seventy per cent the difficulty hitherto experienced is
completely obviated and a cement can be produced having all the characteristics
and qualities of the best Portland Cement The value of this part of the Invention

page_text: is enhanced by the fact that as a general rule wherever a cement rock or hydraulic
limestone formation occurs there are also to be found rocks capable of producing
lime so that there can be obtained on the spot all the ingredients' required for the
manufacture of the Cement according to this Invention
By this part of the Invention a more regular accurate and better Portland
Cement can be produced than by the methods hitherto in use and a very
considerable saving in money and labour is effected
One way in which the Invention may be carried into practical effect is as
follows-
The cement rocks or the hydraulic limestones or both are taken and ground up
raw By analysis it is ascertained what is the chemical composition of the ground
mass in order to determine the extent to which it is deficient in lime and then
there is added to the mass lime in such proportion as to make the manufactured
Portland Cement analyze about Seventy per cent (or say from fifty five or sixty
to seventy per cent) of lime or lime and magnesia
After the addition and incorporation of the lime the powdered or ground mass
is moistened made into bricks or other forms dried calcined to a clinker and ground
into cement under either the "wet" process or the "dry" process as preferred Or
if desired it may be made into cement in accordance with the process hereinbefore.
first described consisting in the mixture with the cement paste before calcination
of a hydro-carbon or other liquid combustible
I have stated that the ingredient added to the ground rock is lime. Under the
term lime I desire to be understood as including lime or dolomite lime which
will slake in water either hydrated or anhydrous or in the form of a carbonate
which after calcination will slake in water. Slaked lime will I believe be found
most convenient in practice
Portland Cement can also be made according to this Invention from ordinary
natural cements such as Rosendale Cement and Cumberland Cement by adding to
them lime in the proportion herein before given and then moistening the mass making
it into bricks or other forms recalcining the same to clinker and then grinding the
calcined product
Portland Cement may also be made according to this Invention from the ordinary
natural cements by first recalcining the latter to clinkers and then regrinding and
adding lime in the proportions hereinbefore indicated. Portland Čement thus
obtained is however more slow setting than that obtained by adding lime to the
mass before calcination
I desire it to be understood that I include within the terms of my claim all of
the foregoing recited methods of applying and using cement rocks or hydraulic
limestones whether raw or in the condition of cements for the purpose of producing
Portland Cement
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is-
First The improvement in the art of manufacturing Portland Cement consisting
in adding to and mixing with the cement material a liquid hydro carbon or other
liquid combustible prior to the calcining operation substantially as and for the
purposes herein before setforth
Second-The improvement in the art of manufacturing Portland Cement which
consists in mixing with the paste from which the Cement is to be made a liquid
combustible then making up this compound into bricks or other suitable forms
and then subjecting the same while still moist to the process of calcination
substantially as herein before setforth
Third-A cement paste composed of hydraulic cement making materials in
combination with & liquid combustible material substantially as hereinbefore
set forth

page_text: Fourth. The improvement in the art of manufacturing Portland Cement
consisting in combining with cement rocks or hydraulic lime stones either before
or after the calcining operation lime in substantially the proportions hereinbefore
stated
Fifth. The process of manufacturing Portland Cement consisting in combining
with ground or pulverized cement rocks or hydraulic limestones, lime in substantially
the proportions stated and subsequently calcining and grinding said compound
substantially as hereinbefore described
Sixth-The hereinbefore described product obtained from the combination.
substantially in the manner herein before described of cement rocks or hydraulic
limestones with lime in substantially the proportions herein before stated
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal this first day of September One thousand
eight hundred and eighty three.