IMPROVEMENTS IN THE MANUFACTURE OF ALKALI
Year: 1878

page_text: LETTERS PATENT to Henry Brunner, of Appleton Widnes, in the County of
Lancaster, Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ALKALI."
Sealed the 7th February 1879, and dated the 10th August 1878.
PROVISIONAL SPECIFICATION left by the said Henry Brunner at the Office
of the Commissioners of Patents on the 10th August 1878.
HENRY BRUNNER, of Appleton Widnes, in the County of Lancaster, Manufacturing
Chemist. "IMPROVEMENTS IN THE MANUFACTURE OF ALKALI."
This Invention relates to improvements in the manufacture of alkali, and consists
in the employment of one or more of the substances constituting what is known as
the charge subsequent to the action of heat upon those constituents which have
been placed in the furnace, revolving or otherwise, and subjected to the action of
heat.
In carrying out my Invention I either charge the furnace revolving or otherwise
with the entire quantity of salt cake and limestone together with a portion of the
slack, and when the charge has been submitted to the action of heat and the desired
decomposition has been effected I add the residual portion of the slack and continue
the operation until the charge is ready to draw; or instead of adding the whole
quantity of the sulphate of soda or salt cake, the limestone, and the slack, I firstly
place in the furnace, revolving or otherwise, the entire quantity of the sulphate of
soda together with the larger proportion of the limestone and slack, and when the
desired decomposition has been effected I add the residual portions of the limestone
and slack and continue the operation, as is well understood, until the charge is
ready to draw.
By adopting either of the processes herein indicated I have found that the residual
portion of the cyanides which are always contained in the resulting lexiviation is
considerably reduced in quantity.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Brunner in the Great Seal Patent Office on the 8th February
1879.
HENRY BRUNNER, of Appleton Widnes, in the County of Lancaster, Manufacturing
Chemist. IMPROVEMENTS IN THE MANUFACTURE OF ALKALI."
«
My said Invention relates to improvements in the manufacture of alkali, and
has for its object to prevent or hinder the formation of cyanides in the black ash
process, and it consists in keeping back the whole or a large proportion of the
mixing slack until the other materials of which the charge in the furnace is composed
have attained a comparatively high temperature.
:
The furnace is first charged with the sulphate to be decomposed together with
the necessary quantity of carbonate of lime (either in the form of limestone, chalk,
or the so-called lime mud produced in the manufacture of caustic soda), and the
materials so charged are heated up to the point of fusion of the sulphate before
adding the mixing slack. After the mixing slack has been added the charge is
worked in the ordinary well-known manner until the operation is completed. I
find that in working in this manner a much smaller proportion of mixing slack is
required than in any other method of working with which I am acquainted, and
the resulting black ash is practically free from cyanides.
But as in carrying out my Invention as above described so considerable an
amount of time is lost in heating the sulphate and the carbonate of lime up to the
fusing point of the former as is not to be compensated by the saving in mixing
slack and the improved quality of the black ash obtained I prefer to work as
follows I charge the furnace with the sulphate to be decomposed and the
necessary quantity of carbonate of lime together with a portion of the mixing slack,
and heat the mixture up to the point of fusion of the sulphate. Owing to the
combustion in the furnace of the slack thus added the required temperature is sooner
reached than when the charge obtains its heat solely from the fire-place, and there
is consequently a considerable saving of time. As soon as the point of fusion is
reached a partial decomposition of the sulphate takes place, causing the mass to
swell up to some extent. As soon as this temporary ebullition has sufficiently
subsided the mixing slack proper is added in one or more portions, and the opera-
tion continued, as is well understood, until the charge is ready to draw. The black
ash so made is practically free from cyanides.
The proportion of slack to be employed in conjunction with the sulphate and the
carbonate of lime charged at the commencement of the operation may vary according
to the quality of the slack and the amount of moisture in the other materials. From
about 25% to 75% of the total quantity to be used may be employed, and the
smaller the proportion so employed the greater will be the ultimate saving of
mixing slack.
It is necessary to the success of my process that the temperature of the furnace
be high throughout the operation.
I have further ascertained that it is not absolutely necessary to the success of my
process to charge the whole of the carbonate of lime at the commencement of the
operation, but that if it be considered advisable to do so portion of it may be
retained to be added subsequently, together with the mixing slack proper, in order
to prevent the coking together of the latter, but such addition of carbonate of lime
must not be made to any extent which will materially reduce the temperature of the
charge, and I do not claim the use of carbonate of lime in this manner as any part
of my Invention.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may he used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as my Invention in improvements in the manufacture of alkali

page_text: is, the keeping back of the whole or of a large proportion of the carbonaceous
material or mixing slack until the other materials of which the charge in the furnace
is composed have reached a temperature at or about which the sulphate fuses, with
the object of preventing or hindering the formation of cyanides.
In witness whereof, I, the said Henry Brunner, have to this my Specification
set my hand and seal, this Sixth day of February, One thousand eight
hundred and seventy-nine.
TIENDY DDTINNED
101
HENRY BRUNNED (L.C.)