A NEW OR IMPROVED METHOD OF PRODUCING ALUMINA, SUITABLE FOR THE MANUFACTURE OF ALUMINIUM
Year: 1881

page_text: LETTERS PATENT to James Webster, of Solihull, in the County of Warwick,
Engineer, for an Invention of "A NEW OR IMPROVED METHOD OF PRODUCING
ALUMINA, SUITABLE FOR THE MANUFACTURE OF ALUMINIUM."
PROVISIONAL SPECIFICATION left by the said James Webster at the
Office of the Commissioners of Patents on the 14th June 1881.
JAMES WEBSTER, of Solihull, in the County of Warwick, Engineer. "A New
OR IMPROVED METHOD OF PRODUCING ALUMINA, SUITABLE FOR THE MANUFAC-
TURE OF ALUMINIUM."
The object of this Invention is to produce a soluble alumina to be used in the
manufacture of the metal aluminium and for other useful purposes at a less cost
than hitherto.
I take the ordinary alum of commerce, or the sulphate of alumina, or other salts
or compounds of alum, and mix therewith about its weight of carbonaceous
matter, by preference gas-pitch or asphalte, and grind the compound to a fine
powder. This mixture I then place in a furnace, retort, or other suitable receptacle,
and heat the same to about 400° to 500° of Fahrenheit's scale, taking care not to
raise it higher, thus driving off the water of crystallisation with a small portion of
sulphuric acid from the alum, at which temperature the pitch and sulphur melt and
combine together with the remainder of the alum, namely, alumina and potass. The
said temperature is maintained for about three hours, the mixture being well
stirred and mixed during this time, and until it attains the consistence of a thick
paste; it is then removed from the furnace and placed upon a stone floor, and when
cool, broken into pieces and sprinkled with a small quantity of hydrochloric acid
and water mixed in the proportion of one volume of acid to four of water. This
mixture is then thrown in a heap, 18 inches thick or more, and occasionally turned
so that it may heat and give off sulphuretted hydrogen gas. When such gas ceases
to rise from the mixture, I add thereto about five per cent. of wood, charcoal, or
lamp-black, and a small quantity of water if required, and well mix them; the
whole is then removed to a mill or edge-stones, and ground to a stiff paste, which

page_text: is then removed from the mill and made into balls, about 1lb. weight each, and
pierced with some four to six holes, to allow the moisture therein to freely escape
during the period of drying; the said balls are then placed in a drying stove, at
first heated to about 100° Fahrenheit, for about two days, when they are transferred
to an oven or stove heated to from 200° to 300° Fahrenheit, and thus remain until
thoroughly dried.
Tho said dried balls are then placed in a vertical retort of fire-clay heated and
kept at a dull-red heat for about 30 hours; during this time when the balls are
thus heated, I pass through them a jet of steam and atmospheric air combined in
the proportion of about two volumes of steam to one volume of air. By this
process the sulphur, ferric sulphate with small quantities of potass and alumina, are
carried over with the vapour, and condensed by being passed through earthenware
tubes and condensers, similar to the process used in the condensing of nitrous or
nitric acid. When the vapour is all given off, the said balls are removed from the
retort and placed to cool. When sufficiently cooled they are again taken to the
mill and there ground to a fine powder. This powder is then placed in a vat with
about seven times its weight of water, and boiled by steam for about an hour, when
the steam is turned off and the contents of the vat allowed to cool; during this
process of cooling the alumina will fall to the bottom of the vat as a thick
precipitate; the potass and sulphur which was left in the alumina being held in
solution by the water. I then draw this liquid off and boil it down dry, when tho
residue will be found to be the crude sulphate of potass.
The said thick precipitate is further washed with water to free it from the
sulphate of potass remaining therein, and is then placed in sacks or frames to drain
and dry, which completes the process.
This alumina may now be used for the manufacture of anhydrous chloride of
aluminium, the metal aluminium, or other purposes where hydrate of alumina or
oxide of alumina are now used.
The liquid containing sulphur, ferric sulphate, and small quantities of potass and
alumina, may be drawn from the condensers and be sold or used in the manufacture
of colors in dying, printing, and other similar purposes.
The sale or use of this bye-product and the crude sulphate of potass will con-
siderably reduce the cost of the manufacture of the alumina. I expect to reduce
the cost of the alumina nearly one-half.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Webster in the Great Seal Patent Office on the
14th December 1881.
JAMES WEBSTER, of Solihull, in the County of Warwick, Engineer. "A_NEW
OR IMPROVED METHOD OF PRODUCING ALUMINA, SUITABLE FOR THE MANU-
FACTURE OF ALUMINIUM.”
The object of this Invention is to produce alumina to be used in the manufacture
of aluminium and for other useful purposes at a less cost than heretofore.
In carrying my present Invention into practice, I take the alum of commerce or
the sulphate of alumina, or other salts or compounds of alum; for this description
I will take the ordinary alum of commerce, and mix therewith about one-third its
weight of carbonaceous matter, by preference gas pitch, which consists chiefly of
carbon with a small portion of sulphur. This mixture is ground to a fine powder
and then thrown into a flat-bottomed furnace, similar to those used in the manu-
facture of soda-ash, and is heated to about 400° or 500° of Fahrenheit's scale, care
being taken not to raise the heat higher, thus driving off the water of crystallization
with a small portion of sulphuric acid from the alum. At the said temperature
the pitch and sulphur combine together with the alum thus dried. This temperature
is maintained for about three hours, the compound being well stirred and mixed
during such time, when it will have attained the consistenco of a thick paste; it is
then removed from the furnace and placed upon a stone floor, and when cool broken
into pieces and moistened with a small quantity of hydrochloric acid and water
mixed in the proportion of one volume of acid to four similar volumes of water.
This mixture is then thrown in a heap eighteen inches thick or more, and
occasionally turned, so that it may heat and give off sulphuretted hydrogen gas.
When such gas ceases to rise from the mixture, about five per cent. thereof of
wood, charcoal, or lampblack is added thereto, with a small quantity of water if
required for grinding the compound down to a thick paste and well mix them; the
whole is then removed to a mill or other grinding apparatus, and ground to a stiff
paste. This paste is then removed from the mill and made into balls, about 1lb.
cach, and pierced with some four to six holes, to allow the moisture therein to
freely escape during the process of drying; the said balls are then placed in a
drying stove, previously heated to about 100° Fahrenheit, for about two days, when
they are transferred to an oven or stove heated to from 200° to 300° Fahrenheit,
and thus remain until thoroughly dried. These dried balls are put into a vertical
retort of fire-clay. Or the mixture in the heap when it ceases to give off
sulphuretted hydrogen gas may be conveyed direct to such fire-clay retort, which,
in either case is then heated to a dull-red heat, and maintained thereat for about
thirty hours. During this time when the mixture is thus heated, I pass through
it a jet of steam and atmospheric air, mixed in the proportion of about two volumes
of steam to one similar volume of air. By this process the sulphur and ferric
sulphate with a small quantity of potass and a trace of alumina are carried over
with the vapour, and condensed by being passed through earthenware tubes and
condensers, similar to the process used in the condensing of nitrous or nitric acid.
This condensed vapour or liquid is really hydrochloric acid in a concentrated state,
contaminated with free sulphuric acid, sulphate of potass, and iron. When the said
vapour is all given off the dried mixture is removed from the retort and placed to
cool; when sufficiently cooled it is again takon to the mill and there ground to a
fine powder, which powder is then placed in a vat or pan with about seven times
its weight of water and boiled by steam for about an hour, when the steam is
turned off and the contents of the vat allowed to cool; during this process of

page_text: cooling the alumina will fall to the bottom of the vessel as a thick precipitate,
the sulphate of potass which was left in the alumina being held in solution by the
water. I then draw this liquid off and boil it down dry, when the residue will be
found to be the crude sulphate of potass.
The said thick precipitate (the alumina) is further washed with water to free it
from any little sulphate of potass that may remain therein, and is then placed in
sacks or frames to drain and dry, which completes the production of the alumina.
This alumina can now be used for the manufacture of anhydrous chloride of
aluminium, the metal aluminium, also for other purposes where hydrate of alumina
or oxide of alumina are now used.
The aforesaid liquid or hydrochloric acid may be drawn from the condensers and
be sold or used in the manufacture of colors in dyeing, printing, and for other
similar purposes.
The sale of this bye-product and the crude sulphate of potass will considerably
reduce the cost of making the alumina. I estimate that I shall by my improved
process reduce by nearly one-half the present cost of producing it.
Having thus fully described and ascertained the nature of my said Invention
and the method of performing the same, I hereby declare that I do not claim the
mixture of carbonaceous matter with alum per se, being aware that prior to my
Invention such mixture has been used; nor do I claim the jet of mixed steam and
air per se, being aware that it has been applied to other uses, but never previously
as now applied to vertical retorts for the production of alumina; but what I do
claim as my Invention and desire to secure by the herein before mentioned in part
recited Letters Patent is,-
Firstly. Extracting the chief portion of the sulphur and ferric sulphato, and
recovering the hydrochloric acid from the compound while in a heated state by
means of a jet or jets of steam and atmospheric air combined, and the method of
performing the same, substantially as described.
Secondly. The improved process as a whole (except the parts disclaimed) of
manufacturing alumina from alum or other sulphates of alumina or salts of alum,
substantially as specified.
In witness whereof, I, the said James Webster, have hereunto set my hand
and scal, this Seventh day of December, in the year of our Lord One
thousand eight hundred and eighty-one.
TAR
WODNARD