IMPROVEMENTS IN THE MANUFACTURE OF SUGAR, APPLICABLE ALSO TO THE TREATMENT OF GLYCERINE AND OTHER ALLIED SUBSTANCES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Farnham Maxwell Lyte at the Office
of the Commissioners of Patents on the 23rd November 1880.
FARNHAM MAXWELL LYTE, of Putney, in the County of Surrey. "IMPROVEMENTS
IN THE MANUFACTURE OF SUGAR, APPLICABLE ALSO TO THE TREATMENT OF
GLYCERINE AND OTHER ALLIED SUBSTANCES."
In the process of refining sugar as ordinarily carried on the syrups or liquors
contain considerable though variable quantities of combined sulphuric acid and of
sulphates or other salts of lime and magnesia. The presence of these substances
interferes with the filtration and crystallization of the syrups.
This Invention consists in an improved method of separating or eliminating
them from the syrups. The Invention is carried into effect by two successive
stages, viz., 1st, by eliminating the sulphuric acid, and, 2nd, removing the lime or
other alkaline earths.
It has been previously proposed to treat the syrups containing these impurities
with hydrate of baryta and with tribasic phosphate of ammonia for the purpose of
eliminating these impurities, but the results of such treatment have been unsatis-
factory because the baryta has been left in solution in the syrup, and the separation
of the impurities has been imperfect. Considerable expense also is incurred by
using such an expensive salt as the hydrate of baryta.
According to this Invention the syrup, saccharine liquors or juices to be purified
are treated first with carbonate of baryta, which, although almost if not absolutely
insoluble in the syrups or the saccharine liquors or juices, yet decomposes the
sulphates of lime, magnesia, and the alkaline earths contained therein and forms an
insoluble precipitate of sulphate of baryta mixed with the slight excess which may
have been added of carbonate of baryta. This precipitate is or may then be
separated by decantation or filtration, or both, and the decanted or filtrated syrup,
saccharine liquor, or juice will be found to be almost entirely free from either
sulphuric acid or baryta.
It is preferable to use precipitated and still wet carbonate of baryta formed by
the precipitation of some soluble salt of baryta with an alkaline carbonate and the
subsequent washing of the precipitate (but any suitable baryta salt may be used, such,
for instance, as the sucrate or saccharate of baryta). If the quantity of carbonate
of baryta added has been considerably in excess, this precipitate can be used again

page_text: for the treatment of further quantities of syrup, saccharine liquor, or juice, until all
the carbonate which it contains is decomposed or converted into sulphate. The
special advantages of carbonate of baryta over hydrate of baryta and other prepa-
rations previously used are, that it is cheaper, far less soluble in the syrup, and
that it leaves any alkalies which may have been originally present in the syrup
in the form of sulphates as carbonates instead of in a caustic condition, and that
therefore the sugar is far less injured during the subsequent boiling.
After having thus separated the sulphates from the syrup, or saccharine liquor,
or juice, the lime is separated by the addition of phosphate of ammonia, preferably
in the form of the tribasic phosphate of ammonia, which causes a precipitate of
insoluble tribasic phosphates of lime and the other alkaline earths, and perfectly
removes any trace of baryta which may have been left in the syrup, or saccharine
liquor, or juice. This precipitate carries down with it a large proportion of the
coloring matters and clarifies the syrup to a very great extent.
The precipitate
may, if desired, be settled off, or it may be filtered without settling.
The carbonate or salts of strontia corresponding to the above mentioned salts of
baryta may, in some cases, be substituted for carbonate of baryta, but not usually
with advantage.
The syrups, saccharine liquors, or juices treated by this process will be found to
filter better, and boil and crystallize more readily in the vacuum pan. In the
treatment of glycerine and other allied substances the mode of procedure is
mutatis mutandis identical.