Year: 1886

page_text: I, THOMAS ROBINSON, of 401 West Street, Tradeston, Glasgow, in the County
of Lanark, North Britain, Manager of Chemical Works, do hereby declare the
nature of this Invention to be as follows, that is to say :-
My said Invention has for its object the manufacture of alum and sulphate of
alumina in an improved manner, and so as to be freer from impurities, especially
iron, than these compounds are as ordinarily made; and my Invention consists
principally in treating the crude sulphate obtained in the ordinary way with a
sulphide.
In carrying out my Invention I calcine the alum yielding material such as shale,
bauxite, china clay, or other aluminous clay, and I treat the calcined material in
the ordinary way with sulphuric acid carrying on the operation sufficiently to
extract all the alumina. I then add sufficient sulphide of calcium (which may be
in the form of what is known as alkali waste) to neutralise any free sulphuric
acid and precipitate arsenic and other impurities.
If the object is to make alum I then add a sufficient quantity of a suitable
chloride such as chloride of potassium or of ammonium; or I may add the alkali
in the form of a sulphate and in that case I also add chlorine or hydrochloric acid.
The iron present is converted into a chloride which is left in solution when the
alum is crystallised out; and the alum thus obtained is of superior quality.
If the object is to make sulphate of alumina I add an excess of sulphide of
calcium and find that after filtering I obtain a liquor very free from iron as well
as from other impurities and which yields crystallised sulphate of alumina of
superior quality and suitable for various manufacturing purposes especially paper
making.
Dated this fourth day of January 1888
EDMUND HUNT,
Applicant's Agent,

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Alum and Sulphate of
Alumina.
I, THOMAS ROBINSON, of 401 West Street, Tradeston, Glasgow, in the County
of Lanark, North Britain, Manager of Chemical Works, 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 manufacture of alum and sulphate of
alumina in an improved manner, and so as to be freer from impurities, especially
iron, than these compounds are as ordinarily made; and my Invention consists
principally in treating the crude sulphate obtained in the ordinary way with a
sulphide.
In carrying out my Invention I calcine the alum yielding material such as shale,
bauxite, china clay, or other aluminous clay, and I treat the calcined material in
the ordinary way with sulphuric acid carrying on the operation sufficiently to
extract all the alumina. I then add sufficient sulphide of calcium (which may be
in the form of what is known as alkali waste) to neutralise any free sulphuric acid
and precipitate arsenic and other impurities. The quantity of sulphide of calcium
required in each case can be easily ascertained by applying well known chemical
tests or by trials and testing the resulting products. If an ordinary strength of
liquor sometimes termed "bog liquor" or yellow liquor" from alkali waste is
used, capable of neutralising about 2 ounces soda per gallon, a gallon will suffice
for neutralising about 2 ounces free sulphuric acid, the quantity of free sulphuric
acid present being ascertained in the manner ordinarily practised in alum works.
In addition to the sulphide of calcium liquor for neutralising the free sulphuric
acid a further quantity of the liquor must be added in the proportion of about a
gallon for every 3 ounces iron present as ascertained by well known tests.
"
If the object is to make alum I then add a sufficient quantity of a suitable
chloride such as chloride of potassium or of ammonium; or I may add the alkali
in the form of a sulphate and in that case I also add chlorine or hypochloric acid.
The quantity of chloride or sulphate of the alkali must correspond to the quantity
of sulphate of alumina present as is well understood by alum manufacturers. The
iron present is converted into a chloride which is left in solution when the alum is
crystallised out; and the alum thus obtained is of superior quality.
If the object is to make sulphate of alumina I add an excess of sulphide of
calcium and find that after filtering I obtain a liquor very free from iron as well
as from other impurities and which yields crystallised sulphate of alumina of
superior quality and suitable for various manufacturing purposes, especially paper
making. It can be ascertained in any case whether sufficient sulphide of calcium
has been added by testing for sulphuric acid and for iron in the manner ordinarily
practised in alum works.

page_text: 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
In the manufacture of alum and sulphate of alumina, treating the crude sul-
phate obtained in the ordinary way with a sulphide substantially as hereinbefore
described.
EDMUND HUNT,
Applicant's Agent.