Year: 1886

page_text: Date of Application, 29th Apr., 1886.
Complete Left, 26th Jan., 1887.
Complete Accepted, 8th Mar., 1887.
I CHARLES JOHN HOWE of S Kensington Park Gardens, in the County of
Middlesex, Barrister at Law, do hereby declare the nature of this invention to be as
follows:-
This Invention relates to the manufacture of cement or plaster.
According to one method I take suitable lumps of gypsum or anhydrite or both,
either in the raw state as hewn or dried and even (in the case of gypsum) partially or
entirely deprived of the water of crystallization by the action of heat, and enclose the
same in a receiver together with an alkaline solution or solution of an alkaline silicate
aluminate or horate, or of borax, or of borax and cream of tartar, or of sulphate of
zinc or iron, or of barium hydrate or lime-water or a combination of these ingredients
and boil under pressure. I then withdraw the fluid and blow through the mass of
gypsum in the receiver if necessary first a current of carbonic acid gas and then a
blast of heated air or jet of super-heated steam. I then withdraw the material and if
necessary further calcine in a furnace and reduce to powder.
Or, I may place the lumps of gypsum or anhydrite or both in an exhausted receiver
to which an alkaline solution is then admitted, pressure being afterwards applied by
means of a force pump until the solution has thoroughly penetrated the lumps. The
receiver is fitted with a hot water or steam-jacket so that if it is desirable to use a
strong hot solution the vessel and its contents may be heated before introduction of
the solution and afterwards kept at a high temperature.
To still further improve the result the solution may he withdrawn and after drying
the lumps, the operation repeated, using the same or other solution of alkali or acid to
neutralize the chemicals already used or the compounds formed by them with the
gypsum and to promote the end I have in view if not sufficiently attained I insulate
the receiver and pass through its contents a current of electricity. I then admit
carbonic acid gas after which I thoroughly dry the mass by a blast of hot or cold air
driven through it. I then calcine the dried mass (when a cold blast has been used or
if it has not been sufficiently heated by the hot blast) in a reverberatory or other

page_text: furnace or by a current of heated air, the air being heated by passing through a
brickwork heater which is kept hot by a furnace, the waste heat being utilized to
support combustion in the furnace. Two such heaters or furnaces may be used
alternately or I may use regenerative furnaces. Or the calcination may be effected
by the direct application of gas flame or heat to the mass placed upon a grate of iron
or fire clay. The calcined mass is then reduced to powder. Or, after the saturating,
and drying or hardening process, I reduce the gypsum to powder and calcine in an
ordinary kiln, finally if necessary passing the powder through a heated tube. Some-
times, in order to calcine or dry in the first instance I place the lumps of gypsum in
a pit and pour upon them a bath of heated sand from a furnace whereby the water
of crystallization will be driven off in the form of vapour with violent ebullition of the
sand. In this manner the gypsum may be calcined very regularly for making either
cement or plaster.
C. J. HOWE.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Cement or Plaster.
I CHARLES JOHN HOWE of 8 Kensington Park Gardens, in the County of
Middlesex, Barrister at Law, 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 relates to the manufacture of cement or plaster suitable for fire-
proofing structures, for rapid plastering, for internal decoration, and for the many
other purposes for which such cements are usually employed.
In carrying out my invention in practice, I take suitable lumps of gypsum which
may either be raw or calcined, and instead of simply dipping them in a solution as
ordinarily practised in the manufacture of Keene's, Parian, and such like cements,
I place them in a suitable receiver, from which the air is then exhausted. I then
admit a solution such as that generally used in the manufacture of the above mentioned
cements, the solution filling the receiver and being put under pressure by means of a
force pump.
A convenient apparatus for the purpose would be one similar to that used in
creosoting timber for example.
If the gypsum has been previously calcined it may be unnecessary to use both the
preliminary exhaustion of air and the subsequent pressure of the liquid and in that
case, one or the other may be dispensed with.
In treating raw, or uncalcined gypsum a hot saturated solution should be used, in
which case, the receiver should be steam-jacketted in order to prevent the cooling of
the solution.
Or, the solution may with advantage be boiled under pressure by the direct
application of heat.
When the gypsum has been completely saturated with the solution it is removed
from the receiver and exposed to a current of air from a fan by spreading it in a thin
layer upon an open drying floor, or in a series of shallow troughs or boxes side by side
(having wooden coverings that can be conveniently removed for the purpose of
spreading and removing the material) the troughs or boxes communicating in such
way that a current of air may be drawn or forced through the whole series and through
or over the layers of gypsum therein contained by a fan or other means. Under the
influence of the air current the material speedily assumes a marble like structure.
is then ready to be calcined in the usual way after which it is ground. The plaster or
cement produced by this rapid process is very uniform in quality and economical to
manufacture.
It

page_text: 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 1 claim is :-
The herein described rapid process of manufacturing plaster or cement, which
consists essentially in saturating the gypsum in vacuo or under pressure and sub-
sequently exposing the saturated gypsum to a forced draught of air as herein
specified.
C. J. HOWE.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.