IMPROVEMENTS IN TREATING THE OXIDE OF IRON RESIDUES OF GAS PURIFYING IN ORDER PRINCIPALLY TO EXTRACT SULPHUR THEREFROM
Year: 1865

page_text: LETTERS PATENT to Thomas Bell, of Plaistow, in the County of Essex,
for the Invention of "IMPROVEMENTS IN TREATING THE OXIDE OF IRON
RESIDUES OF GAS PURIFYING IN ORDER PRINCIPALLY TO EXTRACT SULPHUR
THEREFROM."
Sealed the 24th April 1866, and dated the 2nd December 1865.
PROVISIONAL SPECIFICATION left by the said Thomas Bell at the
Office of the Commissioners of Patents, with his Petition, on the 2nd
December 1865.
I, THOMAS BELL, of Plaistow, in the County of Essex, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN TREATING THE OXIDE OF
IRON RESIDUES OF GAS PURIFYING IN ORDER PRINCIPALLY TO EXTRACT SULPHUR
THEREFROM," to be as follows:-
This Invention has for its object improvements in treating the oxide of iron
residues of gas purifying in order principally to extract sulphur therefrom. The
oxide of iron residues of gas purifying are at present used in the manufacture
of sulphuric acid, the sulphur being at once burnt off as sulphurous acid;
this process is, however, disadvantageous, as the impurities contained in the-
residues render necessary a larger per-centage of nitre than would be.
required if the sulphurous acid were obtained from sulphur or a natural
pyrtes.

page_text: According to my Invention I place the residue when dry in a retort or
vessel which can be closed air-tight, and by a fire outside the retort or vessel
the material is, whilst the air is excluded, heated until the sulphur volatilizes ;
the vapour is led away to a suitable condenser, and there collected;, the
sulphur thus obtained may be used for the manufacture of sulphuric acid and
for other purposes. In some cases I treat the gas residue with hydrochloric
acid which dissolves out the iron, leaving the sulphur contaminated only with
matters which are in no way injurious in the manufacture of sulphuric acid ;;
or this impure sulphur may, by sublimation, be brought into a commercial
form.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Bell in the Great Seal Patent Office on the 1st
June 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BELL, of Plaistow, in the County of Essex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of December, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Bell, Her special licence that I, the said Thomas Bell, my
executors, administrators, and assigns, or such others as I, the said Thomas
Bell, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
TREATING THE OXIDE OF IRON RESIDUES OF GAS PURIFYING IN ORDER PRINCIPALLY
TO EXTRACT SULPHUR THEREFROM," upon the condition (amongst others) that I,
the said Thomas Bell, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Bell, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-

page_text: formed, to be particularly described and ascertained in and by the following
statement thereof; that is to say:-
This Invention has for its object improvements in treating the oxide of iron
residues of gas purifying in order principally to extract sulphur therefrom.
According to my Invention I treat the gas residue with hydrochloric or
other equivalent acid, which dissolves out the iron leaving the sulphur
contaminated only with matters which are in no way injurious in most
manufacturing processes.
:
The following is the manner in which I prefer to proceed :-I take the
gas residue and I wash it with weak hydrochloric acid, such as at many
chemical works is a waste product. This washing may be effected by agitating
the residue with the acid, allowing it to subside and decanting the clear liquor;
or the acid may be caused to filter through the residue; both of these systems
of washing are well understood by manufacturing chemists. A small quantity
only of acid is employed for the first washing, and this liquor which will
contain nearly all the ammonia which was in the residue is kept separate from
the other washings; this same liquor is used for the first washing of different
portions of waste until it becomes charged with iron and ammonia, lime is
then added, and the ammonia is distilled over and absorbed by sulphuric or
other acid, or if caustic ammonia is required it is condensed in water, as is
well understood. The washing with acid is continued until it is found that
the iron which the residue originally contained has all (or practically all) been
dissolved out. The same acid may be repeatedly used, until it becomes so
charged with iron as to be of no further use. In this manner residue con-
taining at the outset 40 per cent. of sulphur is brought up to about 80 per
cent. The purified residue is then thoroughly washed with water until only
the last traces of acid remain, and this may be neutralized by a final washing
with lime water, or the addition of a small quantity of lime. The material is
then dried, and it may, if desired, be melted and cast into rolls in the usual
way. Although still containing some impurities, which spoil its color, it is
then sufficiently pure for use for most manufacturing purposes for which
brimstone is now employed. However, if a purer sulphur is required the
material after it has been dried and before it is melted may be washed with
naphtha or other solvent, which will dissolve out naphthaline and some other
impurities deposited by the gas, and which in some cases are found in suffi-
cient quantity to be worth separating in this manner irrespective of a purer
sulphur being thereby obtained. In place of using, as above described, weak
bydrochloric acid, such as is often a waste product, stronger acid may be
used, indeed an economy of acid and of time, although not usually of cost, is

page_text: obtained by the use of. stronger acid. In place of hydrochloric acid sulphuric
acid-may be substituted; its action is in this process similar and equivalent to
that of hydrochloric acid, but it is more convenient to use hydrochloric acid.
In witness whereof, I, the said Thomas Bell, have hereunto set my
hand and seal, this First day of June, in the year of our Lord One
thousand eight hundred and sixty-six.