Treating the Residual Spent Iron Liquors Resulting from the Manufacture of Copper from Burnt Cupreous Sulphur Ores to Obtain a Certain Oxide of Iron therefrom and Apparatus to be Used therefor.
Year: 1887

page_text: Date of Application, 14th Sept., 1887
Complete Specification Left, 13th June, 1888
Complete Specification Accepted, 24th Aug., 1888
Treating the Residual Spent Iron Liquors Resulting from the
Manufacture of Copper from Burnt Cupreous Sulphur Ores to
Obtain a Certain Oxide of Iron therefrom and Apparatus to be
Used therefor.
I, HENRY BIRD of Southdown House near Devonport in the County of Devon
Chemist, do hereby declare the nature of my said invention to be as follows:-
This Invention relates to the manufacture of a certain oxide of iron known as
gas-oxide" to be used chiefly for the purification of illuminating gas; the matter
from which such oxide is made, being that known as "spent iron liquors" resulting
from the common process of the separation, by precipitation, by iron, of the copper
contained in burnt cupreous sulphur ores.
According to this Invention the spent iron liquor, containing sulphate of iron
resulting from the precipitation, by iron, of the copper in the burnt cupreous sulphur
ore is treated with milk of lime, or lime in a fine state of division.
The mixture is now allowed to settle and a slurry containing hydrated oxide of iron
is precipitated. This slurry is then filtered in a filter press of the ordinary type for
expressing the clear liquor.
When in the press it may be washed with water to free it from the soluble salts it
contains. The hydrated oxide of iron would now be taken from the press and would
be in the form of cakes. The next step of the process consists in mixing homo-
geneously the oxide of iron with a carboniferous substance, preferably sawdust, or
tanwaste. The mixing may be conveniently effected by a mixer of the character of a
pug-mill. or, a mortar mixer. After these materials have been thoroughly intermixed
the iron is oxidized and the mixture is thereby converted into the gas-oxide. The
oxidation is effected most economically by exposure to the atmosphere by spreading the
mixture upon a floor protected from the weather.
In lieu of mixing the liquor directly with milk of lime as above specified it may be
mixed with chloride of calcium, thereby converting the sulphate of iron into chloride

page_text: of iron, the sulphate of lime being precipitated. The clear liquor is then taken and
treated with lime as above specified and the process is completed as before described.
It is stated above that the soluble salts contained in the slurry are removed from it
when in the filter press, but these however may be removed after the mixture of iron
and sawdust or equivalent substance has been subjected to oxidation if it is preferred
to do so.
This may be effected by placing it in a tank with a false perforated bottom and
displacing the soluble salts by adding water to the gas-oxide and allowing it to
percolate through the material. Or both these methods of washing out the soluble
salis may be adopted in combination.
The residual liquor after treating with milk of lime will contain soda salts and these
may be recovered from it by evaporating the liquor in the manner practised in
manufacturing soda by the Le blanc process. A suitable apparatus for treating the
iron liquor, when milk of lime is used in the first instance, consists of a tank for the
iron liquor, and one for the lime. These combine and are mixed in a mixing tank
which may be one sufficiently large to form also a precipitating and settling tank.
Or it may be merely a mixer, in which case one or more settling tanks are employed.
In either case the clear liquor is withdrawn from the tank or tanks in which the
liquor is settled, preferably, by a suitable syphon and the deposited slurry is removed
by a suitable force pump. The clear liquor is delivered from the pump to the filter
press the cakes of hydrate-oxide from the press being taken away and are mixed
roughly by hand with sawdust or equivalent material. They are then mixed homo-
geneously by a mixing machine of the pug-mill or mortar mixing type. When the
material is washed finally to remove the soluble salts it is effected in a lixiviating
tank of the type above specified.
When the iron liquor is treated with chloride of Calcium in the manner herein
specified there will be two tanks in the process beyond those above specified.
These will consist of a chloride of calcium tank and a mixing tank for the chloride of
calcium and the iron liquor; or sets of such tanks may be employed instead
of one.

page_text: Treating the Residual Spent Iron Liquors Resulting from the
Manufacture of Copper from Burnt Cupreous Sulphur Ores to
Obtain a Certain Oxide of Iron therefrom and Apparatus to be
Used therefor.
I, HENRY BIRD of South Down House Devonport in the County of Devon, Chemist,
do hereby declare the nature of my said invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
*
This invention relates to the manufacture of a certain oxide of iron known as gas
oxide" to be used chiefly for the purification of illuminating gas and the removal of
sulphur compounds from other gases; the matter from which such oxide is made
being that known as "spent iron liquors" resulting from the common process of the
separation, by precipitation, by iron of the copper contained in burnt cupreous
sulphur ores.
According to this invention the spent iron liquor, containing sulphate of iron
resulting from the precipitation, by iron of the copper in the burnt cupreous sulphur
ore is treated with milk of lime or lime in a fine state of division. The mixture is
now allowed to settle and a slurry containing hydrated oxide of iron is precipitated.
This slurry is then filtered in a filter press of the ordinary type for expressing the
clear liquor. When in the press it may be washed with water to free it from the
soluble salts it contains. The hydrated oxide of iron would now be taken from
the press and would be in the form of cakes, which are then preferably dried at a low
temperature. A convenient and economical method of drying the iron cakes will be
upon floors constructed with flues or channels covered with iron plates, or bricks,
pipes heing laid in the flues through which exhaust or live steam is passed. The next
step of the process consists in mixing homogeneously the oxide of iron with a
carboniferous or fibrous substance preferably sawdust, or tan-waste. The mixing may
be conveniently effected by a mixer of the character of a pug-mill or a mortar mixer.
After these materials have been thoroughly intermixed the iron is per-oxidized and
the mixture is thereby converted into the gas-oxide. The oxidation is conveniently
effected by exposure to the atmosphere by spreading the mixture upon a floor protected
from the weather.
In the above described process the calcium sulphate formed, is precipitated along
with the hydrated oxide of iron, a portion is however washed out by the lixiviation
but the bulk remains with the iron oxide.
In lieu of mixing the liquor directly with milk of lime as above specified, it may be
mixed with chloride of calcium, thereby converting the sulphate of iron into chloride
of iron, the sulphate of lime being precipitated. The clear liquor is then taken

page_text: pumped by the pump / to the filter press F. The cakes of hydrated oxide of iron are
formed by this process of filter pressing and when discharged from the press are
spread over the drying floor G. The next step of the process consists in adding the
carboniferous or fibrous substance namely the sawdust or other material, which is
done on the floor EI by hand, after which the iron cakes and the sawdust are
thoroughly mixed in the mixer-edge runners-designated I.
The mixture is then spread upon the floor J and exposed to the atmosphere until it is
oxidized. The residual liquor in the tank D and from the filter press F will contain
soda salts which may be recovered from it by evaporating the liquor. When the iron
liquor is treated with the milk of lime direct and without the calcium chloride, the
tanks B and C would be omitted and the iron liquor fed from the tank A to the
tank D.
In erecting a plant such as above described the side of a hill is very suitable as in
such a case the liquors from the tanks A. B and C C and D D could he arranged to
gravitate into each other, and so do away with pumps or syphons.
When complete exhaustion of the soluble salts from the iron cake is desired then
the pressed cake should be thrown into a tank, lixiviated with water and again pressed
before being placed on the drying floor. In cases where economy of space is an
object, the mixture of hydrated oxide of iron and sawdust may be oxydised by being
placed on shelves in a tower, or put into a vessel with a false bottom and then forcing
or drawing air through it.
gas oxide
Having now particularly described and ascertained the object and purposes of my
invention I would state in conclusion that I have described what I consider the best
mode of carrying out the manufacture of "
from spent iron liquor of the
kind herein specified, and the one I prefer to employ, I would have it understood
however that I do not intend to limit my Patent to the precise manner heroin specified
of producing the " gas oxide" since modifications may be made without departing
from the spirit or scope of my invention; for example, if desired, the unmixed iron
cake (hydrated oxide of iron) may be manufactured in one place and then may be
sold or removed and subsequently be mixed with the carboniferous or fibrous
substance, by the buyers or users; I would also state that I do not claim broadly as
new per se or in combination any part of the plant described except as combinations
of apparatus for carrying out the above mentioned manufacture: but what I claim in
respect of the herein described invention is :-
1. The manufacture herein described for use as "gas oxide" consisting of a hydrated
oxide of iron produced from spent iron liquors, of the kind herein specified, in the
manner described said hydrate being subsequently mixed with carboniferous or fibrous
substances and oxidized either before or after mixing, as or substantially as and for
the purposes set forth.
2. The manufacture herein described consisting of " gas oxide produced from
spent iron liquors of the kind herein specified, substantially in the manner herein set
forth.
3. The production of "gas oxide" herein described which consists in (1) treating
spent iron liquors of the kind herein specified with lime (2) filtering and pressing the
precipitate, (3) then mixing a carboniferous or fibrous substance with the hydrated
oxide of iron so produced and (4) then oxidizing it; substantially as set forth.
4. The production of "gas oxide" herein described which consists in (1) treating
spent iron liquors of the kind herein specified with lime, (2) filtering and pressing the
precipitate, (3) then drying the hydrate of iron so produced, (4) then mixing a
carboniferous substance with the dried hydrate of iron and (5) then oxidizing it;
substantially as set forth.
5. The production of " gas oxide" as herein described which consists mainly, in
(1) treating iron liquors of the kind herein specified with Calcium chloride, (2) treating
the hydrated oxide of iron so produced with lime, (3) filtering and pressing the
precipitate thus formed, (4) then mixing the iron with a carboniferous substance,
and (5) then oxidizing it; substantially as set forth.

page_text: 6. In the production of "gas oxide" from spent iron liquors of the kind herein
specified the employment in combination of a spent iron liquor tank, A, a lime tank
or mixer E, a settling or precipitating tank or tanks D, and a filter press F and with
or without a heated drying floor G substantially as set forth.
7. In the production of gas-oxide" from spent iron liquors of the kind herein
specified, the employment in combination of a spent iron liquor tank A, a calcium
chloride tank B, a settling or precipitating tank or tanks D, and a filter press F and
with or without a heated drying floor G, substantially as set forth.
Dated this 12th day of June 1858.
HENRY BIRD.
By Cheesbrough & Royston,
15, Water Street, Liverpool,
Patent Agents.