Year: 1886

page_text: -Date of Application, 18th June, 1886.
Complete Left, 18th Mar., 1887..
Complete Accepted, 19th Apr., 1887.
I SAMUEL LOWDEN of 6 Queensborough Terrace, Kensington in the County of
Middlesex, do hereby declare the nature of this invention to be as follows:-
Portland Cement is, as is well known, composed of Medway blue clay, or equivalent
aluminous compound, inixed with chalk or limestone, the latter ingredient constituting
the greater bulk of the compound.
Experience has shewn that great skill is required in the production of a sound
cement, and that, notwithstanding the desirability of making the cement in the locality
where it is to be used, this course has in general proved impracticable. I have found,
however, that it is practicable to manufacture what may be termed the "nucleus" of
the cement, and transport it in a comparatively small bulk to any locality possessing
chalk or limestone, and there to complete the manufacture of the Cement.
In carrying this invention into practice, I make a combination of Medway blue
clay, and-chalk or limestone, treating the compound in the same manner as when
making Portland Cement. The proportions, however, differ materially :. thus, I take
one part by weight of Medway blue clay, in its natural state, and five parts of chalk or
limestone in its natural state. The material, when thoroughly mixed, dried upon hot
plates, and subjected to a white heat in a kiln, will combine and form the "nucleus "
which I desire to produce, and will be fit for transport to any part where chalk or
limestone abounds, and where the finished product is intended to be employed. To
complete the manufacture, I take chalk or limestone, reduce it to powder, and subject
it to a heat of say 210' Faht. or thereabouts, to drive out the natural moisture
therefrom. I then mix the dried material with the prepared "nucleus," in the
proportion of one part by weight of the chalk or limestone to the three parts of the
nucleus," and I thus obtain a Portland Cement equal in quality to the best of those
in the market.
By this means I am enabled to effect a material economy in the matter of transport,
and to utilize chalk or limestone in localities where it has hitherto been of little
or no use.

page_text: COMPLETE SPECIFICATION..
Improvements in the Manufacture of Portland Cement:
I SAMUEL LOWDEN of 6 Queensborough Terrace, Kensington, in the County of
Middlesex, 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 :-
Portland Cement is, as is well known, composed of Medway blue clay, or an
equivalent aluminous compound, mixed with chalk or limestone, the latter ingredient
constituting the greater bulk of the compound.
Experience has shown that great skill is required in the production of a sound
cement from these materials, and that notwithstanding the desirability of making the
cement in or near the locality where it is to be used, this course has in general proved
impracticable. I have found, however, that it is prácticable to manufacture what may
be termed the nucleus of the cement, and to transport it to any locality possessing
chalk or limestone, and there to complete the manufacture of the cement.
This mode of working possesses many advantages, some of which are obvious, while
others follow from the behaviour of the cement while in its partly manufactured state,
or when forming an ingredient of concrete.
In carrying this invention into practice, I make a combination of Medway blue clay
or equivalent aluminous compound and chalk or limestone, treating the mixture in
substantially the same manner as when making Portland cement. The proportions,
however, of the ingredients will differ materially.
The clay and the chalk or limestone which I employ are crushed and washed in the
usual way to remove extraneous matters therefrom; and in their moist state the two
substances are intimately mixed together in the proportion, by weight, of one part of
clay to five parts of chalk or limestone. When thoroughly mixed, the compound is
run into settling tanks, from which the supernatent water is run off: The deposit
is then removed from the tanks, and dried by artificial heat in the usual way.
When the compound is dried, it is tranferred into kilns and submitted to a white
heat.
As, however, the material has to be burned very hard, I use about more fuel
than is employed in making the ordinary Portland cement. When the fire has
burnt out and the material has cooled down, the kiln is drawn.
The material is then reduced to pieces about the size of a walnut in a stone
crusher, and will constitute the nucleus which it is desired to produce.
As this product is extremely hard, it has little tendency to absorb moisture, a
characteristic of extreme importance, inasmuch as cement is very liable, in transport,
to exposure to the action of water, and great waste is thereby occasioned, portions of
the cement setting in cakes wherever the moisture has gained access.
The partially manufactured cement will then be fit for transport to any locality
where chalk or limestone abounds, and where. the finished product is intended to be
employed.

page_text: To complete the manufacture, I take the chalk or limestone of the locality (say,
for example, that which is obtained in the neighbourhood of Chicago), reduce it to
powder, and subject it to a heat say 210° Fahr. or, thereabouts, to drive out the
natural moisture therefrom. I then mix the dried material with the prepared nucleus
in the proportion, say, of one part by weight of the chalk or limestone to three
parts by weight of the nucleus, and I thus obtain a Portland Cement equal in
quality to the best of those in the market.
The Chicago limestone that I have used in the production of my cement is a
magnesium limestone, which, on analysis, is found to consist of the following
ingredients in or about the proportions given :-
It should be remarked that what I have termed the nucleus is in itself a cement,
but when used as such, from being extremely hard, it gradually deteriorates, whereas,
when mixed with a due proportion of uncalcined limestone as above indicated, it
will, like Portland Cement, increase in hardness after setting. By thus dividing the
manufacture into two distinct processes, I am enabled to effect a material economy
in the matter of transport, to reduce the risk of injury to the material during
transport, and to utilize chalk or limestone in localities where it has hitherto been
of little or no value.
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
The process above described of manufacturing Portland Cement at two stages, that
is to say, forming a nucleus by the combination, under a white heat, of Medway
blue clay or equivalent aluminous compound with chalk or limestone, in or about
the proportions of one part of clay to five of chalk or limestone; and completing the
manufacture by mixing the nucleus compound with uncalcined chalk or limestone as
set forth, and in or about the proportions of three parts of the nucleus to one part of
the chalk or limestone.