Improvements in the Utilization, in the Manufacture of Portland Cement, of Precipitated Carbonate of Lime Forming Waste Products from Chemical Works, and in Apparatus for Employment therein.
Year: 1893

page_text: Date of Application, 9th Mar., 1893
Complete Specification Left, 11th Dec., 1893-Accepted, 13th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Utilization, in the Manufacture of Portland
Cement, of Precipitated Carbonate of Lime Forming Waste
Products from Chemical Works, and in Apparatus for Employment
therein.
I, JAMES HILL, of Avondale, Tettenhall Road, Wolverhampton in the County
of Stafford, Cement Manufacturer, do hereby declare the nature of this invention
to be as follows:-
This invention has for its object an improved process and improved apparatus
for utilizing, in the manufacture of Portland cement, precipitated carbonate of lime
forming waste products from chemical works, such as the carbonated lime mud
resulting from Chance's sulphur recovery process.
In using waste precipitated lime in the manufacture of Portland cement, it has
heretofore been mixed with the clay and washed and ground therewith in the
manner usually or frequently adopted when natural chalk is used for mixing with
the clay.
I have discovered, however, that the grinding of the precipitated lime
is quite unnecessary, and that it may be simply mixed with clay reduced, either
previously or after such mixing or contemporaneously therewith, into a liquid wash
or slurry and the slurry be then dried and burnt in the usual manner without being
first ground. By adopting this process of manufacture I effect a considerable
saving in cost.
The improved apparatus consists of a horizontal barrel, closed at its ends, which
is preferably larger in internal diameter at the middle than at the ends, being
conveniently of a barrel shape or approximately so, and has a central revolving
spindle passing longitudinally through it which carries a number of radiating arms
or beaters which revolve with the spindle. The clay and also some water are,
preferably, first charged in through an opening at the top of the barrel, and the
opening is then closed. Steam is blown in through one end of the barrel near the
bottom and the uncondensed portion escapes through an opening at the top of
the barrel near the opposite end. The arms or beaters break up and disintegrate
the clay and reduce it to a liquid wash, the heat imparted by the steam materially
assisting the process. The precipitated lime is then added through the opening in
the top of the barrel and is thoroughly mixed with the clay by the continued action
of the arms or beaters. When the charge is thoroughly reduced and mixed the
slurry is run out through a door in the bottom of the barrel, and is then dried and
burnt in the usual manner in the manufacture of Portland cement.
The arms or beaters aforesaid may be triangular-shaped in transverse section
and
present a sharp angle in the direction of their rotation.
When the barrel is formed of a larger internal diameter at the middle than at
the ends the discharging door is arranged at the middle, as the slurry of course
drains to such part when the door is opened.
Dated the 8th day of March 1802
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in the Utilization, in the Manufacture of Portland.
Cement, of Precipitated Carbonate of Lime Forming Waste
Products from Chemical Works, and in Apparatus for Employment.
therein.
I, JAMES HILL, of Avondale, Tettenhall Road, Wolverhampton in the County
of Stafford, Cement Manufacturer, 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 using precipitated carbonate of lime, such as the carbonated lime mud
resulting from Chance's sulphur recovery process, in the manufacture of Portland
cement, it has heretofore been mixed with clay in an ordinary wet mixing mill
(such as is commonly used in the manufacture of Portland cement when natural
chalk is used for mixing with the clay), into a wet slurry which is afterwards dried
and burnt. A considerable quantity of water, however, (as in the case of the
ordinary manufacture of Portland cement from clay and natural chalk) is required
to enable the clay to be properly reduced in such mill, and great expenditure of
fuel is consequently necessary to properly dry the mixed clay and carbonate of
lime contained in the slurry, previously to burning the mixture.
Now, the object of this invention is to effect the reduction of the clay in a
manner which enables it to be accomplished with much less water than heretofore,
by the use of apparatus which permits of the admixture therewith of the carbonate
of lime either contemporaneously with such reduction or subsequently thereto,.
whereby, without increasing the cost of reducing and mixing, considerable economy.
is effected in the drying of the mixed clay and carbonate of lime.
.
In describing the invention it will be convenient to describe first the apparatus
employed, and which itself forms an important feature of the invention. This
apparatus is illustrated by the drawings herewith, of which Figure 1 is a longi-
tudinal section through the centre of the apparatus, and Figure 2 is a transverse
section taken through the middle thereof.
This apparatus consists of a horizontal barrel A, closed at its ends by lids B B,
and fixed upon a bed G. The barrel A is, preferably, larger in internal diameter
at the middle as shewn than at the ends, being conveniently made of the shape
shewn, that is to say, with the middle thereof cylindrical and tapering smaller in
diameter from the ends of the cylindrical portion to the ends of the barrel. A
central revolving spindle C passes longitudinally through the barrel and through
packing-boxes on the ends thereof, and is preferably carried in bearings D D fixed
in position beyond the glands of the packing-boxes. On one end of the spindle
are mounted fast and loose pulleys EF, and the spindle is driven through the
medium of the pulley E at a speed of from- 600 to 800 revolutions per minute:
A number of radial arms or beaters a bed are fixed upon the portion of the spindle
which is within the barrel, and consequently revolve with the spindle: The
portion of the spindle which is within the barrel is square, or of other shape in
cross section which will prevent the arms from turning independently thereof
when placed thereon. The arms are, preferably, placed upon the spindle so that,
counting from one end of the set of arms, each succeeding arm follows the one
which it immediately succeeds at an angle of 90 degrees, and thus the outer
extremities of the arms are in the line of a spiral curve around the spindle; and
the arms are, respectively, made of such lengths that their tips come within about
half an inch of the interior surface of the barrel. The arms are, preferably,
made of the shape in transverse section shewn by detached view Figure 3, which
is a sectional shape of one of the arms taken on line x of Figure 2.
The arms
are conveniently of the shape in side elevation shewn by Figure 2, and their sharp
edges are forward and thus when fixed on the spindle in the position shewn by

page_text: Figure 2 the spindle is driven in the direction of rotation indicated by the arrow i-
of such figure. The arms are conveniently fixed by pushing them along the shaft
against an abutment formed by a collar e formed with or fixed to the spindle, and
then tightening them up endways by means of a cotter f and gibb g which pass
through a slotted opening in the spindle. The cotter may be prevented from
shaking loose by forming it, as shewn, with a screwed end which passes through a
hole formed in an upward extension of the gibb g and tightly screwing up a nut on.
the cotter and against the extension of the gibb. A washer is preferably
interposed between the cotter f and the arm adjacent thereto. An opening is.
formed through the top of the barrel, preferably at the middle thereof as shewn,.
and is closed by means of a sliding plate or sluice k. A hopper H (of which the
upper portion is broken away, for convenience of illustration) is fixed over the top
of the opening j, and the materials are supplied to the barrel from such hopper
through the opening j. An opening, corresponding to the opening 1, is formed
through the bottom of the barrel (preferably at the middle thereof, as shewn,
when the barrel is of a larger diameter at the middle than at the ends) and is..
closed by a sliding plate or sluice / working in suitable guides, as shewn.
A steam inlet opening m is formed in one end of the barrel as shewn, and
preferably near to the bottom thereof, and an outlet opening n for the escape of
uncondensed vapour is formed in the top of the barrel near to the opposite end
thereof to that at which the inlet opening m is formed.
The clay and also some water are, preferably, first charged in through the
opening in the top of the barrel, and the opening is then closed. Steam is
admitted through the hole m and the uncondensed portion escapes through the
opening n from which it may be conveyed away through piping. The arms or
beaters break up and disintegrate the clay and reduce it to a stiff slurry or past y
mass, the heat imparted by the steam assisting the process. The precipitated:
carbonate of lime is then added through the opening j which is then closed again,.
and the carbonate of lime is thoroughly mixed with the clay by the continued
action of the arms or beaters. The spindle preferably revolves while the clay is.
charged into the barrel, and also while the carbonate of lime is charged thereinto.
The opening through the bottom of the barrel is kept closed until the charge is.
thoroughly reduced and mixed, but when this has been accomplished the slurry or
pasty mass is discharged through such opening, and is then dried and burnt in the
usual manner in the manufacture of Portland cement. I have discovered that.
owing to the finely divided state in which the carbonate of lime is obtained, the wet
grinding mills employed in the ordinary manufacture of Portland cement may be
dispensed with as the slurry does not require grinding previously to being dried
and burnt.
The spindle is, preferably, kept revolving while the material is being discharged:
from the barrel.
The steam is, preferably, blown into the barrel only during the process of reducing-
the clay; but though it is preferred to use steam during such process its use is not
essential.
The slurry is made as stiff as is consistent with thorough mixing of the clay and
carbonate of lime, so as to lessen as much as may be convenient the quantity of
moisture to be evaporated therefrom; and by the use of the improved apparatus
above described the clay and carbonate of lime may be mixed in a much dryer state
than is the case in mixing slurry in the ordinary wet mixing mill commonly used in.
the manufacture of Portland cement, and thus a great saving is effected in the cost
of drying.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the utilization, in the manufacture of Portland cement, of precipitated'
carbonate of lime forming a waste product from a chemical works, reducing the

page_text: clay into a stiff slurry in a chamber or barrel closed at its ends and provided with a
revolving shaft carrying arms or beaters, and mixing therewith, either during such
reduction or subsequently thereto in the same chamber or barrel, the carbonate of
lime, and then drying and burning the slurry in the usual manner, but without
previously grinding it, substantially as described.
2. In the reduction of clay, within a chamber or barrel closed at its ends and
provided with a revolving shaft carrying arms or beaters, in the process of manu-
facturing Portland cement from clay and precipitated carbonate of lime, the use of
steam within such chamber or barrel to assist in the reduction of the clay, substan-
tially as described.
3. The improved reducing and mixing apparatus for use in carrying out the
improved process above described, substantially as described and illustrated.
Dated this 9th day of December 1893.
STEPHEN
WATKINS,
Wolverhampton, Agent for the Applicant.