Improvements in and in connection with the Manufacture of Iron Sulphate, and of Materials for use in the Filtration and Precipitation of Sewage and Polluted Waters.
Year: 1892

page_text: Date of Application, 18th Oct., 1892
Complete Specification Left, 13th July, 1893-Accepted, 2nd Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in and in connection with the Manufacture of Iron
Sulphate, and of Materials for use in the Filtration and
Precipitation of Sewage and Polluted Waters.
I, FRANK PULLEN CANDY of 56 Nightingale Lane Balham in the County of
Surrey Sanitary Engineer do hereby declare the nature of this invention to be as
follows:-
I take sulphide of iron, for instance iron pyrites, either alone or in conjunction
with other substances and heat or burn it or them at such a temperature and in such
a manner, for example I may give access of air or steam or both to the heated
matter, as to convert all or part of the iron or other substance and sulphur into a
soluble salt, the salt of iron I prefer to obtain being ferric sulphate. wash the
roasted material in water and dissolve out the salt or salts which, if I wish to
obtain in a solid form, I evaporate down or crystallise out or treat as hereafter
mentioned. I use the said salt or salts for the precipitation and deodorization of
sewage and polluted waters or for other purposes to which such salt or salts is or
are applicable or I obtain the salt or salts from the treated material in other ways.
The residue of the sulphide of iron after the extraction of the iron salt I use
for the filtration of sewage and polluted waters. I sometimes carbonise the said
residue with or without the addition of carbonaceous matter:-by carbonise I mean
heating without free access of air.
I sometimes burn the iron sulphide in a similar manner to that employed in the
manufacture of sulphuric acid or I use the residue of the iron sulphide obtained in
the manufacture of sulphuric acid, for the filtration of sewage and polluted waters
either with or without washing in water or acid and with or without carbonisation
as before mentioned.
When I wish to obtain the solution of ferric sulphate procured from the heated
iron sulphide as before mentioned, in a solid form, I mix the solution of the salt
with a suitable material which when acidified will form the whole into a solid mass.
I preferably use a material such as alumina which will crystallise; the said material
when acidified abstracts or uses up the water in the solution of the salt and the
whole is obtained in a solid form for example I take bauxite and mix with it a
solution of ferric sulphate obtained as before mentioned, the said ferric sulphate
solution containing sufficient water for the crystallisation of the sulphate of alumina
to be obtained from the bauxite, I then add sufficient sulphuric acid to dissolve the
bauxite, and allow the mass to set.
I may obtain the solution of any other salt applicable to sewage treatment, in a
solid form in the same way, for instance a solution of any ferric sulphate or ferric
chloride in combination with bauxite or hydrated ferric oxide or other suitable
material, and acid.
Dated this Fifteenth day of October 1892.

page_text: COMPLETE SPECIFICATION.
Improvements in and in connection with the Manufacture of Iron
Sulphate, and of Materials for use in the Filtration and
Precipitation of Sewage and Polluted Waters.
I FRANK PULLEN CANDY of 56 Nightingale Lane Balham, in the County of
Surrey Sanitary Engineer do hereby declare the nature of this invention, and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
I take sulphide of iron, for instance that sulphide of iron known commercially
as iron pyrites, and burn or heat it in such a manner that the sulphur is driven off,
I prefer to allow free access of air to the burning sulphide and also to inject steam
therethrough, I then conduct or force the fumes through or over a layer or layers
of iron oxide, preferably ferric hydrate, or through or over a layer or layers
of aluminium oxide for instance bauxite, or I may use a mixture of the said iron
and aluminium oxides, I sometimes add to the material or materials before-
mentioned a small quantity of manganese dioxide or of other similar oxidizing
agent or agents I prefer to employ the said iron or aluminium oxides or other
substances, in a heated condition."
The result of the beforementioned treatments is that the iron sulphide is
converted into porous iron oxide and iron sulphate while the other oxides of iron
and alumina are converted into iron sulphate and aluminium sulphate. The iron
sulphate I prefer to obtain is ferric sulphate.
When the proportion of sulphates in any or all of the materials employed is
small I prefer to lixiviate the said sulphates out, afterwards evaporating them down
if necessary, and employ them for the precipitation and deodorization of sewage
or impure waters. If all or a great part of the materials employed are converted
into sulphates, I add such material or materials directly to the sewage or waters to
be purified. Instead of utilizing the said sulphates of iron or alumina for the
purification of sewage or polluted waters I may employ them for other purposes to
which they are applicable.
The residue of the iron sulphide after lixiviation I employ as a filtering material
for sewage or impure waters, reducing it first, if necessary, to a suitable size. I
sometimes heat or roast the said residue in combination with carbonaceous matter,
without allowing free access or too free access of air thereto, I thus convert the
said residue into a mixture of ferrous and ferric oxides, preferably black in
appearance.
I use this said heated or carbonised residue as a filtering material; first reducing
it to a suitable size if necessary.
During the beforementioned carbonising process the iron sulphide residue is
brought to a red heat, and it may be necessary to maintain that heat for from three
to eighteen hours; the carbonaceous matter employed may be coal, sawdust, tar,
green oils or other similar suitable substance or substances. I do not carry the
carbonising process so far that metallic iron is produced.
Or I may use as a filtering material, either with or without previous washing, or
with or without carbonisation, as before mentioned, or after both washing and
carbonisation, the spent oxide obtained in the manufacture of sulphuric acid from
iron sulphide. If necessary I reduce by a granulation process the said spent
oxide or the treated spent oxide to a suitable size for filtration purposes. Such a
suitable size is that of fine gravel or coarse sand, or a mixture of these sizes. Any
of the filtering materials before mentioned may be used mixed with sand.
Or in place of the spent oxide obtained from the iron sulphide used in the
manufacture of sulphuric acid, I may burn iron sulphide in a similar manner, and
then use it as before described.
When I wish to obtain in a solid form the solution of ferric sulphate produced

page_text: from or in connection with the burnt pyrites as before described, instead of
evaporating it down I sometimes use the said solution in place of the water
employed in the manufacture of a salt of iron or salt of alumina, from iron oxide
or aluminium oxide: the method I preferably employ is as follows, I take the
solution of ferric sulphate and mix with it iron oxide, for instance hydrated ferric
oxide or aluminium oxide for instance bauxite or a mixture of both, the whole
being ground to a slurry, I then add sufficient sulphuric acid to the mass to dissolve
the oxides of iron or aluminium, and allow the mixture to set, heat being applied
thereto if necessary; the solution of ferric sulphate must contain sufficient water
to allow the reaction between the iron oxide or aluminium oxide to take place.
I prefer rather to employ the said aluminium oxide than the said iron oxide. In
place of the ferric sulphate produced as before mentioned I may use ferric sulphate
produced in other ways or I may use ferric chloride.
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―
1. The manufacture of sulphates from iron pyrites and from iron oxide and
aluminium oxide substantially as described.
2. For the filtration of sewage or polluted waters the use of burnt pyrites
substantially as described.
3. For the filtration of sewage or polluted waters the use of burnt pyrites either
washed or lixiviated, or carbonised or both substantially as described.
4. For the filtration of sewage or polluted waters the use of burnt pyrites
reduced to a suitable size substantially as described, the said burnt pyrites having
or having not undergone other treatment either previous to or after granulation
substantially as described.
5. The use of a solution of ferric sulphate or ferric chloride in place of the water
employed in the manufacture of iron sulphate or aluminium sulphate substantially
as described.
Dated this 26th day of June 1893.
F. PULLEN CANDY.