Sharpening, Grinding, and Polishing Stones for Metals and other Hard Substances
Year: 1868

page_text: reverberatory furnace, taking care however to renew by stirring the
Burface exposed to the direct action of the heat; but besides this
manner of working being more costly the grains of emery will have less
tooth or cutting power, as the pulverizing operation will break down or
round the angles. This mode of manufacture is specified as a modifi-
cation of the principal process. All the varieties of bauxite can be
applied to the manufacture of artificial emery, and the quality of the
product will be in proportion to its richness in alumina.
II. Sharpening, Grinding, and Polishing Stones for Metals and other
Hard Substances. Artificial emery powder alone or mixed with crude
bauxite dust in a state of fineness more or less great according to the
nature of the article to be produced may be moulded by compression
or by any other simple manner of moulding, with the addition of the
binding materials specified above. The particles will be agglomerated
by firing, so as to form numerous utensils or articles used for domestic
purposes, and which serve to sharpen and polish metals, stones to whet
scythes, and sharpen knives, and carpenters' or joiners' tools, stones to
polish marbles, glass, crystal, and in short for all instruments and
materials for which natural emery is or can be used.
III. Grindstones, Millstones, and Polishing Stones.-The manufacture
of artificial grindstones and millstones is one of the most important
objects of this Invention. The artificial emery powder can be applied
to the manufacture of emery wheels, such as those generally in use, and
for which purpose natural emery powder is combined with caoutchouc,
glue, gelatine, or any other known suitable substance. Artificial emery
powder can be substituted for a quartz sand much used by Mr. Ransome
in his manufacture of artificial grindstones, in which to the homogeneity
and the perfection of form of these grindstones is added the durability
of cutting or polishing material.
Some of the objects of the present Invention it will be seen are the
applications of the artificial emery to existing manufactures, but it may
also be applied to the manufacture of grindstones or millstones on
various improved methods.
The first system consists in the agglomeration of the artificial emery
powder in the form of millstones by means of firing, as has already
been described above, taking care that the hardness is uniform through-
out,

page_text: The mass composed of hard grain and unattackable by steel tools
should be of such a structure that the shock of the dressing tools will
be able to cut or renew the surface, and, if desired, regulate its
inequalities.
To obtain the first condition when using ordinary furnaces the aid
of the brickmakers' and potters' art is called in, so that the articles may
be placed in the best possible position in the furnace, and also for the
better management of the fire the arrangement and change of position
of the articles in the reverberatory furnaces, upon the hearth of which
the stones or articles, solidified by a preparatory drying or stoving or
the free action of the fire may be rolled along the hearth of the furnace
from the chimney to the hottest part.
The second point is effected in two ways, first, by firing at a
high temperature a mixture of artificial emery and pure bauxite moulded
by compression, or by adding a small quantity of binding material or
in increasing the proportion of the emery, and stopping the firing at a
point where the mass will still preserve the necessary degree of friability
required for the cutting process. Thus, for example, fifty to sixty per
cent. of artificial emery with fifty to forty per cent. of fine bauxite
powder, and two to five per cent. of chalk or of chloride of calcium, or
five to six per cent. of fusible clay with a long and well managed firing
will be found to give very good results. The proportions given are not
absolute, they are not given as invariable, but simply as examples;
but in any case great care must be taken in firing in order
that the stone should not become too hard for the action of the
tools.
The second system consists in binding the materials together by means
of a quick or slow setting mortar of artificial emery and plaster or lime,
more or less hydraulic, or Portland cement, or other analogous products
which may be mixed with gelatine, dissolved glue, the alkaline or
silicate, in order to increase the tenacity of the paste.
The only pre-
cautions necessary are those usually employed in making mortar with
a large proportion of sand so as to get it soft; hot bitumen, pitch, or
asphaltes may also be employed for this purpose. It is understood
that in all these cases pressure may be used to increase the density and
molecular cohesion of the materials. This mode of agglomerating the
materials is applicable also to the manufacture of sharpening stones,
hones, or the other articles mentioned above.

page_text: IV. Grinding and Crushing Stones.-The great hardness, tenacity,
and density of articles manufactured from bauxite allow of its appli-
cation for crushing stones to be used in place of grindstones of porphyry
and granite.
In order to properly carry out this application a quantity
of artificial emery heated to a high temperature is introduced into the
mixture before firing, so that any warping of the articles when in the
furnace should be avoided. In millstones for grinding flour the least
ferruginous bauxites should be used so that the flour may not be
discolored.
V. Paving and Kerb Stones. By mixing artificial emery in largish
grains with fusible clay or other binding materials, and treating the
mass in the manner before described, very good paving kerb stones or
tiles for floors will be obtained. In some cases powdered bauxite
agglomerated by means of the binding matters already indicated may
be employed; for instance, white tiles are made by mixing bauxite
purified by muriatic acid with pipeclay and a small quantity of
chloride of calcium; or red tiles are made by mixing ferruginous bauxite
heated in an oxydizing flame with ferruginous clays.
VI. Bricks, Pottery, and other Articles of a Refractory Nature.-For
bricks, parts of furnaces, crucibles, retorts, muffles, and other vessels or
articles for various purposes in the arts, tuyeres of melting and other
furnaces, Bessemer converting vessels, pipes for heating air, or conducting
gas under pressure, the bauxite may be usefully employed.
No special precautions are required in the manufacture of these
articles other than those which would arise from the want of plasticity
in the pasty mass.
The density of the products and their resisting power during the
necessary manipulations that precede the firing will be increased by
making them under pressure, and this will allow of reducing the pro-
portion of the agglomerating or binding material. For fire-bricks the
mixture may consist of artificial emery powder or calcined bauxite with
thirty to forty per cent. of refractory clay (fire-clay). In bricks for
puddling furnaces a mixture of forty to sixty per cent. of calcined bauxite
with sixty to forty per cent. of crude bauxite, with four to six per cent.
of chloride of calcium, or three to four per cent. of quicklime, or two
to six per cent. of chalk or calcined marl, may be advantageously
employed.

page_text: The employment of chlorides of calcium and magnesium necessitates
a special precaution being taken with regard to the rapid drying of the
moulded articles, and of passing them through the fire without exposing
them to the action of the cold and humid atmosphere for a longer
period than is absolutely necessary.
VII. The Hearth and other Parts or Sides of Furnaces Moulded on
the Spot. Artificial emery may be employed with advantage alone or
mixed with crude pulverized bauxite for the hearths, sides, fire-places,
bridges, and other parts of various kinds of furnaces, and these parts
may if required be made in one piece. The composition of the mixtures
will vary according to the parts to which the substance is to be applied.
The mode of applying the bauxite is the same as when sand and other
matters are used for analogous purposes; care must, however, be taken
to have a sufficient quantity of artificial emery included to avoid cracks,
and should any cracks occur they must be stopped by means of a grout
of fine artificial emery powder, with the addition of a suitable binding
substance if necessary.
In constructing domes, arches, or roofs the
centres should be in metal, so that the materials may be well dried
before the centering is removed.
Having now described the Invention that has been communicated
to me, as aforesaid, I would observe that the present Invention has for
its object the application of bauxite and other analogous substances
under whatever name they may be known to the production,―
-1
First. Of artificial emery to be employed in any way in which natural
emery may be used, or for such purposes as the low price of the artificial
emery will allow it to be used.
Second. To the manufacture of hones or grindstones for sharpening
and polishing tools of every description, and for working and polishing
metals and other hard substances.
Thirdly. To the manufacture of millstones for grinding and crushing
grain and other substances.
Fourthly. To the manufacture of paving stones, kerb stones, or tiles
for floors.
Fifthly. To the manufacture of bricks, potteryware, and other articles
of a refractory nature.

page_text: Sixthly. To the hearths, sides, and other parts of furnaces which are
capable of being moulded on the spot.
In witness whereof, I, the said Alfred Vincent Newton, have
hereunto set my hand and seal, the Twenty-eighth day of January,
in the year of our Lord One thousand eight hundred and sixty-
nine.
Witness,
J. W. MOFFAtt,
66, Chancery Lane.
A. V. NEWTON. (L.S.)