Improvements in the Manufacture of Portland Cement.
Year: 1898

page_text: Date of Application, 25th July, 1898-Accepted, 24th Sept., 1898
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Portland Cement.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention (as communicated to me from abroad by La Societie anonyme des Ciments
et Platres de Vilvorde a Vilvorde, Belgium) and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
It is known that the burning of cement stones or artificial lumps require, for
good output and quality, a quantity of fuel which may be reckoned at about 350
kilogrammes of coke per ton or 1000 kilogrammes of Portland cement whether
natural or artificial, or an equivalent quantity of fuel other than coke to give the
same heat value.
If the quantity of fuel be reduced much of the cement remains unburnt, and the
cement in consequence contains much free lime and is of specific gravity less than 3.
By burning the material in an atmosphere saturated with sodium chloride, which
is easily obtained by throwing on the successive charges of fuel and lumps about
50 kilogrammes of sodium chloride per 10 tons of cement material very different
results are obtained and qualities of cement which may be thus stated.
1. The burning is much more active, allowing of a much smaller amount of fuel
being emploved, that is to say about 250 kilogrammes of coke, or its heat produc-
ing equivalent instead of 350 kilogrammes per ton of cement produced. The
chemical reactions due to the burning are facilitated and the stones present the
character of good fusion as desired for cement stones: -
2. The time of burning is greatly reduced:-
3. The proportions of the unburnt material such as occurs in the usual process
is in large measure reduced: -
4. The cohesion of the burnt stones is considerable and their specific gravity
greater than that of ordinary cement.
5. The specific gravity of the moulded cement is increased and exceeds 3 for
the natural cements of Tournay.
is
6. The colour of the burnt stones is greenish grey, that of the moulded cement
slate colour.
grey
7. The cements burnt with sodium chloride give the chemical reactions of the
best ordinary cement, presenting no free sodium chloride.
8. The cement burnt with sodium chloride presents the characters of the best
slow setting cement, tension experiments with the dynamometer and of resistance
to compression and steam give the best results.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is:-
In the manufacture of Portland cement, the addition of sodium chloride in the
kilns, in order to facilitate the burning of both natural and artificial cement

page_text: materials, the said addition permitting the reduction in large proportion of the
fuel necessary for the complete burning of the cement stones, and also giving
better manufacturing results, substantially as and for the purpose set forth.
ABEL & IMRAY,
Agents for the Applicant.