Improvements in the Utilization of a Waste Product and in the Manufacture of Cement and Porcelain.
Year: 1888

page_text: Improvements in the Utilization of a Waste Product and in the
Manufacture of Cement and Porcelain.
OWAIN HUGHES Aber C. E. School Bangor Teacher do hereby declare the nature
of this invention to be as follows:-
In the slate quarries of Wales and other places it will be observed that all the slates
blasted or otherwise taken from the quarry is not turned to profit and only a certain
quantity is made into slates the remaining part, which is very large, is thrown away as
useless rubbish.
Now I have found that this debris can be turned to profit by using the same for
the manufacture of cement and porcelain. I propose the slate to be ground or otherwise
pulverized into very fine powder & mixed in suitable proportions with similarly or
otherwise powdered glass, flints, or any other fusible material and made into a
uniforum paste with water or other liquid, this when formed into vessels and sufficiently
heated, will make excellent porcelain.
I have found that if slate and limestones be burnt, roasted or calcined together or
separately and then reduced to powder, or if first ground and then, heated or burnt,
the compound thus formed will inake excellent cement.
I have also found that slate after being roasted or calcined, be introduced together
with limestones into a blast furnace till the oxide of iron contained in the slate is
detached from its clay, the lime will combine with the clay and form a fusible glassy
compound which I propose to utilize for the inanufacture of porcelain.
I do not however confine myself to these details.

page_text: COMPLETE SPECIFICATION.
Improvements in the Utilization of a Waste Product and in the
Manufacture of Cement and Porcelain.
OWAIN HUGHES Aber C. E. School Bangor, N. Wales Teacher 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 :—
Owing to the various causes affecting the cleavage of slates in the slate quarries a
very considerable amount of rock is wasted and thrown away as rubbish or rubble.
This waste is inevitable in the working of a slate quarry and the proportion which
finished slates bear to the mass of rock removed is about 1 to 10 or 1 ton of finished
slates for every 10 tons of rock removed thus leaving a waste product of 9 tons. In
some quarries this amount of waste is far exceeded. Now I have found that this
rubble can utilized in the manufacture of cement as a substitute for ordinary clays
.puzzolanos and muds that are used for the manufacture of other cements.
If cement, or cement stones from which cements are manufactured, be submitted to
a chemical analysis they will be found to be composed of (a) silica (b) alumina
(c) magnesia (d) oxide of iron and manganese, (e) carbonate of lime. All cements
contain these ingredients in different proportions either in combination or separately.
From the following table it will be seen that slate will bear a very satisfactory
comparison with the best cement stones in use.
From the above table it will be seen that slate is very rich in the hardening
ingredients-silica and alumina-it also contains in addition to the above table a
proportion of alkalies (soda & potash) which will better promote the formation of
silicates of lime and alumina during calcination. It will also be observed that slate
contains less lime, a deficiency which which I propose to obviate by adding separately,
a quantity of lime in the proportions hereinafter stated.
The artificial, as well as the naturall puzzolanos imported from Civita Veccia,
employed in the manufacture of cement contain, silica, alumina, lime, soda & potash,
oxide of iron, magnesia and water. If slate be compared with puzzolano it will be
found to contain the same ingredients and nearly in the same proportions.

page_text: Slate will therefore form an excellent substitute for puzzolanos, for which purpose
propose to utilize slate in the manufacture of cement.
1
Now having given the chemical analysis of slate and compared it with that of
cement stones and puzzolanos, I find that a cement can be made from the mechanical
combination previous to calcination, of lime and slate in suitable proportions, but as
the proportions are liable to variations according to the quality and properties of the
cement required, I do not confine myself to the exact details in any of the several
proportions.
A cement made of these ingredients will have an advantage over other
cements which are apt to vary as the clay from any one pit is not always the same
and constant, but lime and the different kinds of slate being always constant in their
properties, a cement made of these will possess always the same property.
I will now proceed to state the different proportions of the ingredients for the
manufacture of cements. Silica should be present in a quantity varying from 2 to 4
times that of alumina and sometimes it should even amount to 7 or 11 times, so that
a preponderance of silica even to that extent will not affect the cementitious qualities
of the material, but the quality of cement it produces.
The quantity of lime, iron, alkalies should be also variable in each cement so that
an exact and fixed proportion is not essential for the production of a good cement,
the lime should range from 84 to 11 for every unit of alumina.
Ground slate and pure rich lime should be mixed in the proportion of about 20 per
cent. of the former to about 80 per cent. of the latter or 20 per cent. of slate to
140 per cent, of carbonate of lime. If the slate contain any ingredient contained in
the lime, or vice versa, less of that ingredient should be added or should the slate be
dificient in any of the necessary ingredients it should be added in the required
proportion. In mixing the ingredients the carbonate of lime should be present in the
proportion of about 60 per cent. of the whole mass the silica 23 alumina 11 and the
remaining 6 composed of the various other ingredients found in the slate, or, in other
words, in a mixture of 100 parts 60 to 48 should be carbonate of lime and 40 to 42
of slate, or the mixture of lime and slate should have the ingredients in nearly the
following proportions.
T
50

page_text: Should the mixture be found deficient in iron a proportion of red iron ore or yellow
ochre should be added. I do not however confine myself to these details or the
proportions.
The greatest possible care should be taken to ensure a perfect mixture of the lime
and slate for other wise the molecules of the silicate of alumina cannot enter into
perfect combination with the lime; the fineness to which the cement is ground will
practically determine its adhesive powers. It would be advisable to mix the powdered
slate with the carbonate or sub-carbonate of lime to ensure these results. The ingre-
dients should be ground previous to calcination in a sufficient quantity of water and
subinitted to a similar treatment as that adopted in the manufacture of cements, and
submitted to a great heat sufficient to produce a pyrogenic compound of the silicate
of alumina and lime. After calcination it is again ground in the manner adopted
and sifted through sieves of suitable dimensions.
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 herein described new manufacture of cement consisting of ground slate in
combination with lime.
•
2. The utilization of slate waste in combination with lime for the manufacture of
cement.
3. The use of slate waste ground or otherwise as a substitute for trass, puzzolanos,
clay, or any matter in which silica, alumina, alkalies, iron, manganese, magnesia or
any other ingredient found in slate are present, for the manufacture of cement in
combination with lime.
4. The use of slate waste in combination with lime as substitute for cement
stones or similar matter for the manufacture of cement & should the mixture be
deficient in any ingredient it should be added in the requisite proportion substantially
as described.
5. The combinations herein-before stated substantially as described.