An Improved Process for Producing Pure Acetic Acid.
Year: 1899

page_text: Date of Application, 18th. Mar., 1899-Accepted, 1st July, 1899
COMPLETE SPECIFICATION.
An Improved Process for Producing Pure Acetic Acid.
I, FRANZ JOSEF BERGMANN, of 5, Möhnestrasse, Neheim on the Ruhr, in the
German Empire, Manufacturer, 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, that is to say :-
This invention relates to an improved process for the production of pure acetic
acid from crude acetate of lime lycs, and is based upon the formation of the known
double salt from acetate of lime with chloride of calcium. This double compound
eliminates itself easily from sufficiently concentrated solutions in the form of a
crystalline magma or pulp. The compound itself is not liable to change under
the action of air, and precipitates in an almost perfectly pure state even from
impure acetate of lime lycs. From the double salt pure acetic acid may be
obtained by distillation with a suitable acid. If for decomposing the double salt
concentrated hydrochloric acid be employed, chloride of calcium can
obtained from the residue of the distillation and be re-introduced into the process.
As an example the following proportions are used:
be
158 kilogs. of acetate of line, dissolved in as little water as possible, and
111 kilogs. chloride of calcium, also in a very strong solution are brought together.
Theoretically 269 kilogs. of the double salt ought to be obtained, but in reality
the quantity is less on account of the high solubility of this salt. The yield of the
latter will increase according to the concentration of the lyes and according to
the low temperatures of the same. It is preferable to have the concentration of
the solution of acetate of lime not less than 14° B., and of the chloride of calcium
not less than 60° B.
The calcium chloride lye is added to the acetate of lime solution, and the pro-
duct then concentrated by evaporation until the liquid, upon cooling down, be-
comes solidified to a mass of needle like crystals. After cooling, the crystalline
magma or pulp is subjected to centrifugal action with the result that the lye thus
separated in the centrifugal apparatus contains the largest porcentage of the im-
purities, whereas the magma or pulp is obtained in an almost perfectly pure state.
The double salt thus produced (either with or without previous drying) is then
distilled with an acid, preferably hydrochloric acid.
Unlike former processes, the improved process is such that the drying and cal-
cining of the acetate of lime is avoided, and that, on distilling the product, a pure
acid is obtained directly without any further rectification.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what
I claim is:
1. The process for producing pure acetic acid from crude acetate of lime lyes,
which consists in adding a calcium chloride lye to the said crude acetate of lime
lyes, concentrating the product by evaporation, treating by centrifugal force the
crystalline double compound thus obtained, and subsequently subjecting the said

page_text: compound to distillation by means of an appropriate acid, substantially as set
forth.
2. My improved process for producing pure acetic acid, substantially as herein-
before described.
Dated this 18th day of March 1800
'
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 6A, Market Street, Nottingham,
Agent for the Applicant.