AN IMPROVED METHOD OF MANUFACTURING LIQUID SULPHATE OF ALUMINA, WHEREBY IT IS RENDERED APPLICABLE TO DIFFERENT INDUSTRIES IN WHICH SULPHATE OF ALUMINA IS AT PRESENT EMPLOYED IN THE FORM OF CAKE
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Thomas James Smith at the Office
of the Commissioners of Patents on the 10th April 1877. Cominunicated
from abroad by Emile Victor Constant Bichon, Chemical Manufacturer, residing
at Montpellier, Herault, France.
THOMAS JAMES SMITH, of the Firm of Robertson, Brooman, and Company, of
166, Fleet Street, in the City of London, Patent Agents. "AN IMPROVED METHOD
OF MANUFACTURING LIQUID SULPHATE OF ALUMINA, WHEREBY IT IS RENDERED
APPLICABLE TO DIFFERENT INDUSTRIES IN WHICH SULPHATE OF ALUMINA IS AT
PRESENT EMPLOYED IN THE FORM OF CAKE." Communicated from abroad by Emile
Victor Constant Bichon, Chemical Manufacturer, residing at Montpellier, Herault,
France.
This Invention has for object the manufacture of liquid sulphate of alumina by
means of hydrated alumina, the richness of which varies from 60 to 80 per cent.
The liquid sulphate of alumina thus manufactured can be employed in tho
different branches of industry where it is at present employed in the form of cake.
Into a leaden vat of 30 hectolitres, which can be heated by steam piping, is placed
150 kilogrammes of hydrated or powered alumina of a richness of 80 per cent., or
120 kilogrammes of real or pure alumina; if the material contains only 60 per cent.
of alumina, 200 kilogrammes would be necessary; in a word, 120 kilogrammes of
real alumina can be employed. Upon this powder is poured 550 kilogrammes
of sulphuric acid at 50 degrees centigrade, the whole being diluted to a clear pulp;
a steam cock is opened, and the mixture becomes heated; at the expiration of 10
minutes chemical combination commences and is maintained at a temperature of
130 degrees until completed.
The sulphuric acid combines with the alumina and forms sulphate of alumina,
the combination occupying about one hour. Water is added for the first operation,
and the wash water from the bottom for the second. The vat is filled with water,
which then indicates about 15 degrees Beaumé.
In each operation such a quantity of water is added that the degree of the acid
gauge is always the same.
If for the manufacture of papers which do not require to be very white, the
solution is allowed to settle. The clear solution is poured off into another vat
alongside, from which the workmen can take each day the number of decalitres
necessary for each paper vat.

page_text: If the lower vat contains 30 hectolitres, since there are 120 kilogrammes of
alumina in solution, each hectolitre contains 4 kilogrammes of alumina, or 30 kilo-
grammes of sulphate of alumina, and consequently each decalitre contains 3 kilo-
grammes of sulphate of alumina.
For all papers, which must be totally exempt from any trace of iron, three kilo-
grammes of prussiate of potassa disolved by a kilogramme of peroxide contained in
the alumina employed is added to the solution in the first-named vat. At the end
of 24 hours it can be poured off into the second vat; the whole can be then taken
up into an upper vat, and water coming from a pipe washes this residue. The wash
water is employed for the following operations:-
The upper vat is filled by degrees with Prussian blue and its residues, because
the sulphate of iron being in contact with the prussiate of potassa becomes changed
into insoluble Prussian blue, and takes the form of sulphate of potash.
When the upper vat is full of blue and the residues, a prussiate is regenerated
under the form of prussiate of soda. For this purpose 78 kilogrammes of caustic
soda is boiled. The Prussian blue, in the presence of the hot soda, is transformed into
prussiate of soda, and precipitates the peroxide of iron. This last is utilized in the
manufacture of lighting gas. The prussiate is therefore in constant use, save the
insignificant losses occasioned by manipulation.
This second method of treatment by the prussiate is only necessary to obtain
sulphate of alumina quite exempt from iron.
In a case where the alumina contains 3 per cent. of peroxide of iron, as the
quantity mentioned above gives 900 kilogrammes of sulphate of alumina, it is
scarcely a three-thousandth part of peroxide of iron that the non-purified liquor
contains, consequently, as one thousand kilogrammes of paper require 40 kilo-
grammes of sulphate of alumina, there are 120 grammes of peroxide of iron intro-
duced into a 1000 kilogrammos of paper, far too feeble a proportion to influence
the colour to an appreciable extent.
The following figures show the results of an operation •
The net cost is thus 8 francs per 100 kilogrammes of manufactured sulphate of
alumina.
The material costs scarcely 2000 francs in place, and can be kept in a surface of
30 square metres.
This method gives therefore 5 per cent. of economy upon the actual price of
sulphate of alumina in cake. It has the further advantage of never giving an
excess of sulphuric acid since there is always an excess of alumina left. It is seen
in addition that the liquid sulphate of alumina thus manufactured may be employed
direct, without previous evaporation, by paper makers, tanners, dyers, and others.
If the manufactured sulphate of alumina contains traces of blue it can be eliminated
by means of filters.