Improvements in the Manufacture of Portland Cement from Hard Limestone.
Year: 1889

page_text: Date of Application, 8th Oct., 1889
Complete Specification Left, 27th June, 1890-Accepted, 20th Sept., 1890
ROY DIUNAD DEMUITIQATION.
Improvements in the Manufacture of Portland Cement from Hard
Limestone.
WILLIAM THOMAS TIMEWELL of 23 Oxford Street Totterdown Bristol in the
County of Somerset Portland Cement Maker do hereby declare the nature of this
invention to be as follows:-
This invention has for its object to make cement from hard limestone such as the
hard mountain limestone found in Somersetshire, Wales, Derbyshire, and bath free-
stone found in Wiltshire, and Portland stone found in Dorsetshire, or any other
limestone, preferable, that will make white lime that contain from 70 to 96 per cent.
of carbonate of lime the limestone is reduced to a fine powder and mixed with inland
fresh water silicated clay, or tidal river silicated mud, that contains from 60 to
cent. of silica.
75
per
I reduce the limestone to a fine powder through millstones or pulverizing machines
so that 75 per cent. of the whole will pass a 80 guage sieve 6400 mmeshes to the square
inch I then prepare it in a dressing machine through a 60 guage wire sieving or
bunting clothi 3600 meshes to the square inch I prefer separating the fine from the
coarse with a blowing machine or fan driven at a high speed to exhaust the impalpable
powder from the machine as it is being ground and blow the same into a stive or
collecting chamber.
I then mix the powdered limestone with silicated clay or silicated tidal mud, with
water in a mixing machine similar to a clay pug mill driven at the speed of
100 revolutions per minute I then grind the wet mixture through two pairs of ordinary
corn millstones driven at the usual speed, to form an impalpable slurry, then I dry
out the moisture and burn it in a cement kiln at a high temperature to cause fusion,
I then grind it to a fine powder so that it will pass a sieve of 2500 meshes to the
square inch, so I produce good Portland cement.
I burn the dried slurry into clinkered cement in kilns with drying floor attached to
the flue of each kiln to utilize the waste heat which is conducted through flues under
iron plates leading to the chimney stack, this forms a drying floor as the wet mixture
leaves the mixing machine it is ground through millstones, from thence pumped onto
the drying floors, and dried with the waste heat from the kiln when burning a previous
loading of dried slurry.
In mixing the materials 1 work it through two mixing machine kept running at
full speed, when one machine is full-I pass the same through millstones, whilest the
other machine is being filled, by these means every mixture is finished separately, in
this I do away with continuous running mixtures, so as to ensure the production of
cement of high and regular quality.
The proportions of mixing the materials are guided by the quantity of carbonate
of lime in the stone, and the silica and alumina in the clay, or mud, from three to
four parts, or five parts of carbonate of lime by weight to one by weight of silica
and alumina allowing for the moisture in either of the materials.
Dated this Seventh day of October 1889.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Portland Cement from Hard
Limestone.
I WILLIAM THOMAS TIMEWELL of 23 Oxford Street Totterdown Bristol in the
County of Somerset Portland Cement Maker, 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:-
This invention has for its object to make Portland cement from hard limestone
such for example as the hard mountain limestone found in Somersetshire, Devonshire,
Wales, Derbyshire, and bath freestone found in Wiltshire, and Portland stone found
in Dorsetshire, or any other limestone preferable that will make white lime, or that
contains from 80 to 98 per cent. of carbonate of lime. The limestone is reduced to
a fine powder and mixed with inland fresh water silicated clay, or tidal river silicated
mud, preferable that contains from 60 to 75 per cent. of silica and from 16 to 25 per
cent. of alumina and iron.
I reduce the limestone to a fine powder by means of millstones or pulverizing
machines preferable that 75 per cent. of the whole will pass a 80 guage sieve
6400 meshes to the square inch, I then prepare it in a dressing machine through a
60 guage wire sieving or bunting cloth 3600 meshes to the square inch, I prefer
separating the fine from the coarse with a blowing machine or fan driven at a high
speed to exhaust the impalpable powder from the machine as it is being ground, and
blow the same into a stive or collecting chamber.
I then mix the powdered limestone with silicated clay or silicated tidal mud with
water in a mixing machine similar to a clay pugmill driven at the speed of
100 revolutions per minute, I then grind the wet mixture through one, or two, pairs
of 4 feet ordinary corn millstones driven at the usual speed, to form an impalpable
slurry, then I dry out the moisture and burn it in a cement kiln, at a high temperature
that will cause fusion, I then grind the burnt clinker to a fine powder preferable that
it will pass a sieve of 2500 meshes to the square inch, so I produce good Portland
cement.
I burn the dried slurry into clinkered cement in kilns with drying floors attached to
the flues of each kiln, and utilize the waste heat which is conducted through flues
under iron plates leading to the chimney stack.
As the wet mixture leaves the mixing machine it is ground through millstones from
thence pumped on to the drying floors and dried with the waste heat from the kiln
when burning a previous loading of dried slurry.
In mixing the raw materials I work it alternately through two mixing machines
kept running at full speed, when one machine is full I grind the same through
millstones whilest the other machine is being filled by these means every mixture is
finished separately so I do away with continuous running mixtures and the uncertainty
of results incidental to the soft chalk processes, thus ensures the production of a
cement of high and regular quality.
The proportions of mixing the materials are guided by the quantity of carbonato
of lime in the stone, and the silica and alumina in the clay, or mud, from three to
five parts of carbonate of lime by weight, to one by weight of silica and alumina,
allowing for the moisture in either of the materials.
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:
The manufacture of cement from hard limestone and silicated aluminous clay, or
tidal mud containing silica and alumina substantially as herein before defined.
13
W. T. TIMEWELL.