Improvements in the Manufacture and Burning of Portland Cement.
Year: 1886

page_text: Date of Application, 18th Nov., 1886.
Complete Left, 11th Aug., 1887.
Complete Accepted, 13th Sept., 1887.
Improvements in the Manufacture and Burning of Portland Cement.
We, HENRY MACEVOY of 404 Camden Road, HENRY HOLT of 15 Stock Orchard
Crescent, both in the County of Middlesex, LEADHAM WHITE of 2 Lime Street Square
in the City of London, Cement Manufacturers, and WILLIAM WILDERS of 19 High
Street, Northfleet, in the County of Kent; Manager of Cement Works do hereby
declare the nature of this invention to be as follows:-
In the manufacture of Portland Cement it has before been proposed to add coal
breeze or other suitable material to the chalk and clay from which the cement is to be
made and to grind these materials together before loading them into the kilns it has also
been proposed to so admix with the chalk and clay a portion only of the fuel that is
required for burning it and to load the materials into the kiln together with the further
quantity of fuel required for burning it. Up to the present time however no satis-
factory results have been obtained when, making cement in this way owing to the large
proportion of breeze which has been ground in with the other materials.
According to our invention we grind in with the materials breeze or suitable fuel in
the proportion of about to of the total amount of the fuel required. The breeze or
other fuel is added to the wet slurry in the wet mill and is there mixed and ground
with it or the mixing and grinding might be effected by any other suitable
machinery.
The slurry thus ground and mixed with breeze is dried on floors or in chambers
and the kilns are loaded with this dried slurry together with hard coke in the ordinary
manner. The clinker obtained is afterwards ground in the ordinary manner but
owing to the porous or honey-comb state in which the clinker is obtained it will be
found that the cost of grinding is materially reduced.
Much less fuel is necessary in loading kilns with this improved dried slurry and a
heavier burnt and in every way superior cement is obtained.
Dated this 19th day of November 1886
CARPMAEL & Co.,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture and Burning of Portland Cement.
We, HENRY MACEVOY of 404 Camden Road, HENRY HOLT of 15 Stock Orchard
Crescent both in the County of Middlesex, LEEDHAM WHITE of 2 Lime Street Square
in the City of London, Cement Manufacturers and WILLIAM WILDERS of 19 High
Street, Northfleet in the County of Kent Manager of Cement Works, 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 :-
In the Specification of a former Patent granted to William Goreham and Leedham
White No. 99 in the year 1870 it was proposed to add coke breeze or other carbon-
aceous fuel to the chalk and clay from which the cement is to be made and to grind
these materials together before loading the mintofthe kilns and it was also proposed to so
admix with the chalk and clay a portion only of the fuel that is required for burning
it and to load the materials into the kiln together with the further quantity of fuel
required for burning it.
In the Specification of another Patent granted to William Goreham it was also
proposed to grind the materials from which cement is made with the breeze in a wash
mill with a small quantity of water and which we call the wet mill.
In the first of the specifications above mentioned it was stated that it was preferred
to use ground or powdered coke breeze in the proportion of 30 lbs. to the bushel of
finished cement and to use in addition from 10 to 15 lbs. of coke.
Up to the present time however no satisfactory results have been obtained when
making cement in this way and for some time past the use of breeze has been entirely
abandoned. We have found that the cause of failure was the large proportion of
breeze used and that if the breeze be used in much smaller proportion a highly satisfactory
result is obtained not only by reason of a saving in the cost of fuel used but also
because a heavier burnt and in every way superior cement is obtained and we have
further found not only that coke breeze can be so used but also that coal breeze or
dust or small coal can be used with still greater advantage a considerably smaller
quantity of such coal dust being requisite than when coke breeze is used.
So far as we are aware no cement has ever been made with coal breeze or powder or
small coal ground in with the cement material.
If it had been ever attempted to use coal dust in anything like the proportions
indicated in the above mentioned Specification no successful result could possibly
have been obtained. In the first place it would have been almost impossible to prevent
the slip from burning on the drying floors, and if not, then the slip would either be
burnt to dust in the kiln instead of to clinker or would cake together in a mass and
choke the kiln.
According to our invention we when using coke breeze use the breeze in a propor-
tion not exceeding 25 lbs. of breeze to the 100 lbs. of finished cement and use there-
with about 15 lbs. of coke.

page_text: Preferably we use 21 lbs. of breeze and 22 lbs. of coke for every 100 lbs. of finished
cement.
When using small coal or coal dust we use the coal in a proportion not exceeding
15 lbs. of coal to the 100 lbs. of finished cement.
Preferably we use the coal in the proportion of 10 lbs. of coal to the 100 lbs. of
finished cement and use therewith in loading the kiln about 22 lbs. of coke.
When using anthracite coal dust we use a still smaller percentage. By preference
we use such coal dust in the proportion of 8 lbs. to the 100 lbs. of finished cement and
use therewith in loading the kiln from 15 to 22 lbs. of coke.
From the above figures it will be seen that by using small or powdered coal we are
able to effect a great saving in the total amount of fuel used so that not only a very
large saving in fuel is effected but in addition a material part of the fuel used is a
fuel of which large quantities are always attainable and which is of small cost.
The breeze or small coal is added to the wet slurry in the wet mill (called the wash mill
in the Specification of Goreham's Patent No. 196370) and is there mixed and ground with
it or the mixing and grinding might be effected by any other suitable machinery. The
slurry thus ground and mixed with breeze or small coal is dried on floors or in cham-
bers and the kilns are loaded with this dried slurry together with the hard coke in the
ordinary manner. The clinker obtained is afterwards ground in the ordinary manner
but owing to the porous or honey comb state in which the clinker is obtained it will
be found that the cost of grinding is materially reduced.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is :-
1. The grinding of coke breeze with slurry in a proportion not exceeding 25 lbs. to
the 100 lbs. of finished cement and subsequently burning the slurry in kilns together
with coke substantially as described.
2. The grinding of powdered or small coal with slurry in a proportion not exceed-
ing 15 lbs. of coal to 100 lbs. of finished cement and subsequently burning the slurry
in kilns together with coke substantially as described.
Dated this 11th day of August 1887.
CARPMAEL & Co.,
Agents for the Applicants.