Improvements in the Manufacture of Sulphuric, Nitric, and Nitrous Acid, and of Sulphate of Soda, Oxide of Iron, and Alumina.
Year: 1895

page_text: Date of Application, 5th Feb., 1895
Complete Specification Left, 4th May, 1895-Accepted, 8th June, 1895
Improvements in the Manufacture of Sulphuric, Nitric, and Nitrous
Acid, and of Sulphate of Soda, Oxide of Iron, and Alumina.
I, WILLIAM GARROWAY, of Netherfield Chemical Works, Duke Street, in the
City of the County of Glasgow, North Britain, Manufacturing Chemist, do hereby
declare the nature of this invention to be as follows:-
This invention relates to improvements in the manufacture of sulphuric, nitric
and nitrous acid, and of sulphate of soda, oxide of iron and alumina.
In accordance with my said invention I mix together proto-sulphate of iron
(copperas) and nitrate of soda, and subject this mixture to a moderate temperature,
by which I obtain nitric acid, with some nitrous acid, which pass off, and may be
employed in the manufacture of sulphuric acid or recovered by any well-known
means, while sulphate of soda associated with peroxide of iron remains behind as a
residue. This residue I treat with water, in which the sulphate of soda dissolves,
while the oxide of iron remains insoluble and constitutes a fine red pigment of
considerable commercial value.
انه
In carrying out my invention or improved process I either grind separately and mix
together, or grind together the protosulphate of iron and the nitrate of soda, and heat
the mixture in the ordinary way. I can use the protosulphate of iron either with the
whole of its contained water of crystallization, or after a portion of that has been
removed by previous heating. During the process the sulphuric acid acts upon
the nitrate of soda, producing sulphate of soda, which remains as a residue, mixed
with the peroxide of iron, while the nitric acid accompanied by some nitrous acid is
volatilised. I can then separate the sulphate of soda by treating the residue with
water, which dissolves it, settling or filtering the solution, and concentrating it to
obtain Glauber's salts in the usual way, while the oxide of iron requires only to be
washed and dried in order to bring it into a marketable condition.
I have also found that sulphate of alumina or alum treated in the same way
yields nitric and nitrous acids, as well as sulphate of soda which remains associated
in this case with pure alumina, which like the oxide of iron, may be separated by
treatment with water, and is then left in a marketable condition.
In heating my retorts containing the said mixtures I may either employ heat
specially generated for the purpose, or in the application of the resulting nitric
acids for the sulphuric acid manufacture the heat of the pyrites or sulphur kilns
or burners.
Dated this Fourth day of February 1895

page_text: Improvements in the Manufacture of Sulphuric, Nitric, and Nitrous
Acid, and of Sulphate of Soda, Oxide of Iron, and Alumina.
I, WILLIAM GARROWAY of Netherfield Chemical, Works, Duke Street,
Glasgow, 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:-
My invention relates to an improved process by which I obtain nitric and
nitrous acid which may be advantageously employed in the manufacture of sulphuric
acid, and to the production at the same time of sulphate of soda, oxide of iron and
alumina.
In carrying out my invention I mix together proto-sulphate of iron (copperas)
and nitrate of soda and subject this mixture to a moderate temperature, by which
I obtain nitric acid and nitrous acid, which pass off, and may be employed in the
manufacture of sulphuric acid, or they may be recovered by any well known means,
while sulphate of soda associated with peroxide of iron remains behind as a residue.
This residue I treat with water, in which the sulphate of soda dissolves, while the
oxide of iron remains insoluble and constitutes a fine red pigment of considerable
commercial value.
In practically working or carrying out my invention I grind separately and mix
together, or grind together, 556 parts of the proto-sulphate of iron and 340 parts
nitrate of soda, both by weight. These are chemically equivalent proportious, but
as neither of these substances are known commercially in a pure state, the proper
allowance must be made for such impurities as may be present. In any case I do
not confine myself strictly to these proportions as I find in practice that they may vary
without detriment to the process. Thus, I can use for example 2 parts of commercial
proto-sulphate of iron to 1 part of commercial nitrate of soda, both by weight. I can
also use the proto-sulphate of iron either with the whole of its contained water of
crystallization or after a portion of that has been removed by previous heating.
The mixture so produced I place in pots or retorts made of cast iron or other
suitable material, in which I then heat the mixture, preferably up to a dull red
heat. During the process of heating the sulphuric acid combines with the soda,
producing sulphate of soda which remains as a residue mixed with the peroxide of
iron, while the nitric acid accompanied by nitrous acid is volatilized. These acids
may be either led directly into the sulphuric acid chamber for use there, or they
may be recovered by condensation or by other well-known means. I then treat
the residue in the retorts with water, hot or cold, by which I dissolve out the
sulphate of soda from the oxide of iron. The former I can recover as Glauber's
salts by evaporation and crystallization in the usual way: the latter I wash with
water and dry it, after which it is ready for the market. I find that the oxide of
iron prepared in this way is of superior quality in respect that it is free from all
acidity which is so objectionable in the oxide of iron made by roasting copperas, in
the ordinary way.
I have also found that sulphate of alumina or alum treated in the same way
yields nitric and nitrous acids.as, well as sulphate of soda, which remains associated
in this case with pure alumina, which like oxide of iron may be separated by treatment
with water and is then left in a marketable condition.
In heating my pots or retorts containing the said mixtures I may either employ heat
specially generated for the purpose, or, in the application of the resulting nitric
acids for the sulphuric acid manufacture, the heat of the pyrites or sulphur kilns
or burners.
1 do not consider it necessary to give any drawing of the plant or apparatus, as

page_text: I find that the "nitre pot" usually employed in the manufacture of vitriol serves the
purpose very well, as far as that manufacture is concerned. Where the nitric
acids are to be condensed or otherwise employed, however, it will be necessary
to use such retort or vessel as is commonly in use for the manufacture of nitric
acid.
Having now particularly described my invention and the manner of carrying it
out, now declare that what I hereby claim is :-
First. The preparation of nitric and nitrous acids by heating a mixture of proto-
sulphate of iron and nitrate of soda, in the manner substantially as hereinbefore
described.
Second. The preparation of sulphate of soda by heating a mixture of proto-
sulphate of iron and nitrate of soda, in the manner substantially as hereinbefore
described.
Third. The preparation of oxide of iron by heating a mixture of proto-
sulphate of irou and nitrate of soda, in the manner substantially as hereinbefore
described.
Fourth. The preparation of alumina by heating a mixture of sulphate of
alumnina or alum with nitrate of soda, in the manner substantially as hereinbefore
described.
Fifth. The preparation of nitric and nitrous acids by heating a mixture of
sulphate of alumina or alum with nitrate of soda, in the manner substantially as
hereinbefore described.
Sixth. The preparation of sulphate of soda by heating a mixture of sulphate
of alumina or alum with nitrate of soda, in the manner substantially as hereinbefore
described.
Dated this 2nd day of May 1905
JOHNSONS,
115, St. Vincent Street, Glasgow, Applicant's Agents.