Improvements in Obtaining Caustic Soda or Caustic Potash by Means of Boracic Acid.
Year: 1889

page_text: Date of Application, 2nd Nov., 1889
Complete Specification Left, 29th July, 1890-Accepted, 30th Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Obtaining Caustic Soda or Caustic Potash by Means
of Boracic Acid.
I, WILLIAM GARROWAY, of Netherfield Chemical Works, Glasgow, in the County of
Lanark, North Britain, Manufacturing Chemist, do hereby declare the nature of this
invention to be as follows, that is to say :-
My said invention has for its object the obtaining of caustic soda or caustic potash
from chloride or sodium or chloride of potassium, or from sulphate of soda by means
of boracic acid, in an improved, simple, and economical manner.
In carrying out my invention I calcine or heat in a suitable furnace or retort a
mixture of boracic acid, chloride of sodium or chloride of potassium, and nitrate or
sulphate of soda or of potash. Hydrochloric acid is evolved and may be condensed
by known means, whilst borate of the alkali remains along with the nitrate or sulphate.
The said nitrate or sulphate is added to the original materials to promote their fusion,
and to modify the condition of the melt or resulting mass, so that it may be the more
easily and economically dealt with in the subsequent grinding and other operations.
The alkaline borate obtained by the calcining operation is dissolved and treated
with lime whereby caustic soda or caustic potash are obtained and borate of lime.
The borate of lime is precipitated, and the solution containing the caustic alkali, after
being separated, is concentrated in the ordinary way.
The boracic acid is recovered so as to be used over again, by treating the borate of
lime with the hydrochloric acid resulting from the first operation, or with other suit-
able acid such as sulphuric acid, chloride or sulphate of calcium being obtained as a
bye product.
Dated this First day of November 1889.
EDMUND HUNT,
Annlicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Obtaining Caustic Soda or Caustic Potash by Means
of Boracic Acid.
I, WILLIAM GARROWAY, of Netherfield Chemical Works, Glasgow, in the County
of Lanark, North Britain, Manufacturing Chemist, 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: -
My said invention has for its object the obtaining of caustic soda from chloride of
sodium, or caustic potash from chloride of potassium, by means of boracic acid, in an
improved, simple, and economical manner.
In carrying out my invention I calcine or heat a mixture of boracic acid with
chloride of sodium or with chloride of potassium in a suitable furnace, such for
example as is in use for decomposing chloride of sodium with sulphuric acid; or the
operation may be effected in an externally heated retort. A small proportion of
nitrate or sulphate of the alkali is, by preference, added to the original materials to
promote their fusion, and to modify the condition of the melt or resulting mass, so
that it may be more easily and economically dealt with in the subsequent grinding and
other operations. The action between the materials is also facilitated by injecting
superheated steam amongst them. The proportions of the materials which I prefer to
employ are 248 parts by weight of crystallised boracic acid to 117 parts of chloride of
sodium, or 159 parts of chloride of potassium; but one half the stated proportion of
boracic acid may be used, aborate or biborate being formed accordingly as the smaller
1נ0 ...

page_text: or larger proportion is used. Hydrochloric acid is evolved and may be condensed by
known means, whilst a borate or biborate of the alkali remains along with the small
proportion of nitrate or sulphate which may have been added.
The next operation consists in dissolving the alkaline borate or biborate and treating
it with lime, the proportion of lime employed being about 148 parts to 117 parts of
the original chloride of sodium or to 159 parts of the original chloride of potassium
the mixture is well agitated and boiled or heated under more or less pressure and
yields caustic soda or caustic potash which is in solution and borate or biborate of
lime which is precipitated. The caustic solution is separated by decantation or
filtration and may be concentrated or otherwise treated in the ordinary way.
The boracic acid is recovered so as to be used over again, by treating the borate
or biborate of lime with hydrochloric acid which may be that resulting from the first
operation, or it may be treated with another suitable acid such as sulphuric acid
chloride or sulphate of calcium being obtained as a bye product.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
The obtaining of caustic soda or caustic potash by the improved processes herein-
before described, in which processes the chloride of sodium or potassium is heated
with boracic acid to obtain a borate or biborate, such as borate or biborate being sub-
sequently treated with lime to obtain the caustic alkali whilst the boracic acid is
recovered for reuse by treating the borate or biborate of lime with hydrochloric or
other suitable acid.
Dated this Mmentr'oighth dox of 1000
EDMUND HUNT,
Applicant's Agent.