Constructing Purposes.
Year: 1887

page_text: Date of Application, 21st May, 1887
Complete Left, 20th Feb., 1888
Complete Accepted, 23rd Mar., 1888
General Constructing Purposes.
ALBERT BUSCH Chemist Palatine Hotel Bridge Street Stockton on Tees do hereby
declare the nature of this invention to be as follows:-
By mixing blast furnace slag with magnesium usta (Mg 0) and with chalk and by
grinding and mixing these materials together I obtain a product that closely resembles
the material known as Portland Cement and suitable for the same purposes.
As Magnesium usta is an expensive article I would in practical work prefer to use
a earthly substance which in combination contains magnesium and chalk and is called
Dolomit and which has the following chemical formal viz. Ca CO3 + Mg CO3.
The Dolomit must have been heated in suitable ovens to certain degrees of heat.
It is afterwards ground and mixed with the slag by suitable machinery and in
suitable proportions.
I have also discovered that the quality of many cements are improved by an
admixture of magnesium usta and chalk or of Dolomit that has been prepared in a
suitable manner.

page_text: General Constructing Purposes.
ALBERT BUSCH Chemist of 22 Mall Road Hammersmith formerly of Palatine
Hotel Stockton on Tees, 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:-
The object of my invention is to produce a material with the qualities of good
Portland Cement from a mixture of Blast Furnace Slag Calcined Magnesia (Magnesia
Usta) and Chalk or from the two first ingredients alone and I will now describe how
I propose to prepare this new Cement. By Furnace Slag I understand the Slags
obtained from the melting of Iron both in the state in which they are generally found
by the Furnaces as hard stones or fallen to fine powder but preferably such as are
rendered cementitious or more cementatious by the process called granulation of slag,
which means that the slag has been suddenly cooled or disintegrated while in its hot,
molten state, by means of water, steam air or special contrivances.
By calcined Magnesia I understand Magnesia, either pure or in combination with
other substances, which has been heated to such a temperature that the Magnesia has
lost all or most of its carbonic acid gas and has been rendered caustic and sometimes
I also hydrate i.e. slake it.
By chalk I understand any sort of chalk or limestone not calcined i.e. burnt.
Perfectly pure Magnesia being a very costly material to produce I prefer in
practice to use an earthly substance which chiefly contains magnesium and chalk and
is generally termed "Dolomite" and which is sometimes expressed by the chemical
formula Ca CO, + Mg CO₂.
As the chalk, contained in the Dolomite for my purpose is extraneous matter more
or less I prefer to use the Dolomites which contain comparatively much magnesium
and little chalk.
It being essential that, when burning or calcining the Dolomite, the magnesium
only is made caustic i.e. made to loose its carbonic acid gas, care must be taken that
the temperature in the kiln, whatever description of kiln be used is not raised
sufficiently high for the chalk also to give off its carbonic acid gas and even if this
cannot be entirely avoided, my object will be attained practically by keeping the
temperature of the kiln at about from 300-450° Centigrade.
Having now explained the treatment to which I submit my raw materials I will
proceed to explain how I utilize the raw materials thus prepared for the purpose of
cement making.
Having taken care that my materials viz. Slag, Magnesia and chalk or Slag and a
Dolomite, which latter as explained consists of magnesia and chalk, are perfectly dry,
I grind to a powder by suitable machinery. Sometimes I grind each separately and
afterwards mix in the requisite proportions and sometimes I mix before grinding.
The materials thus ground and mixed is my finished product, that which I call cement

page_text: for building and other purposes, and it will thus be seen that I do not submit my
product to any calcination after mixing.
The proportions I take of my various raw materials naturally depends upon
their chemical composition, but in practise I have found the following mixture
suitable viz. :
2 parts by weight of Slag
1 do.
1 do.
"
"
""
do.
do. Magnesia
Ohalk
دو
or the two latter ingredients represented by calcined Dolomite. These proportions
I have found to give good results but I do not limit myself to them. Sometimes I
make the cement without chalk, using slag and magnesia only and sometimes
I improve the quality of my cement by the addition of such substances as are
commonly used for improving other slag cements. Obviously I could add other
cement to my mixture and could add lime in substitution of, partly or wholly, or in
addition to the Dolomite or chalk and magnesia; but that would not constitute an
improvement.
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. The manufacture of hydraulic cement from a mixture of Blast Furnace slag and
calcined Magnesia or from slag, calcined magnesia and chalk by grinding mixing and
incorporating these materials in the manner and by the means herein described
.and without calcining the various materials after mixing them.
2. The preparation of Dolomitic Limestone (Dolomite) for cement making by
burning it at such a temperature that practically only the magnesium and not the
chalk looses its carbonic acid gas as herein described.
Dated this 20th day of February 1888.
ALBERT BUSCH.