IMPROVEMENTS IN THE TREAT- MENT OF SPENT OXIDE OF IRON ARISING FROM THE MANUFACTURE OF GAS FOR THE PURPOSE OF OBTAINING CERTAIN VALUABLE PRODUCTS, AND FOR REN- DERING THE SAID OXIDE AGAIN FIT FOR USE
Year: 1877

page_text: LETTERS PATENT to Peter Spence, of Manchester, in the County of Lancaster,
Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN THE TREAT-
MENT OF SPENT OXIDE OF IRON ARISING FROM THE MANUFACTURE OF GAS FOR
THE PURPOSE OF OBTAINING CERTAIN VALUABLE PRODUCTS, AND FOR REN-
DERING THE SAID OXIDE AGAIN FIT FOR USE."
Sealed the 29th April 1878, and dated the 5th November 1877.
PROVISIONAL SPECIFICATION left by the said Peter Spence at the Office of
the Commissioners of Patents on the 5th November 1877.
"
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist. IMPROVEMENTS IN THE TREATMENT OF SPENT OXIDE OF IRON ARISING
FROM THE MANUFACTURE OF GAS FOR THE PURPOSE OF OBTAINING CERTAIN
VALUABLE PRODUCTS, AND FOR RENDERING THE SAID OXIDE AGAIN FIT FOR USE."
I take the spent oxide of iron used in the manufacture of gas containing, as is
well known, certain valuable substances, and place it in tanks of any convenient
form, and by water, either hot or cold, I dissolve and wash out any compounds of
ammonia it may contain. I now let the material drain until tolerably dry, after
which I take unslacked lime, equal to one-half of the washed spent oxide, and slake
it into a fine dry powder, and intimately mix the two together. I then place the
whole in tanks, preferably of iron, each having a false bottom pierced with numerous
small holes, and each having a pipe rising from under the false bottoms to the
surface, and through which water or solutions can be poured directly into the spaces
between the bottoms and false bottoms of the tanks. I now pour water through
the pipes until it rises over the material, which water I find may be heated to 150°
or 160° F., but I believe at present not nearer the boiling point. The water now
overflowing may be used as hereafter mentioned, or passed into another tank to
strengthen it. In either case it is run into a reservoir, and settled until clear of:all

page_text: sediment; it is then run into precipitating vessels, and has added to it a solution of
perchloride of iron, with a slight excess of hydrochloric acid until no more precipi-
tation takes place. The precipitate is Prussian blue, which having been washed is
made into pulp blue or dry Prussian blue, as is well known; or, after the washing,
I add to it a sufficient quantity of potash to decompose the Prussian blue, and the
solution so formed I boil up until it is ready to crystallize prussiate of potash. The
spent oxide having had all the prussiate of lime washed out is now submitted to
boiling by blowing steam into the space between the bottoms. A dark brown solution
of sulphide of calcium being formed, and this I continue to boil and run off until all
is extracted. This solution I run into another series of tanks. After settlement, and
when cold, I add to it hydrochloric acid until the liquor has a slightly acid reaction.
Sulphur is now precipitated, and this I wash, drain, and dry, after which it is fit
for most of the purposes for which brimstone is used. The lately spent material in
the tanks, after having been drained and dried, is fit for again being used in the
purification of gas.
SPECIFICATION in pursuance of the conditions of the Letters Patent.filed by
the said Peter Spence in the Great Seal Patent Office on the 4th May
1878.
"
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist. IMPROVEMENTS IN. THE TREATMENT OF SPENT OXIDE OF IRON ARISING
FROM THE MANUFACTURE OF GAS FOR THE PURPOSE OF OBTAINING CERTAIN
VALUABLE PRODUCTS, AND FOR RENDERING THE SAID OXIDE AGAIN FIT FOR USE."
The material to which my Invention refers is the hydrated oxide of iron now
generally used for the purification of illuminating gas, and when, having become
spent, it is no longer of use in the said purification, and has to be replaced by a
new charge. In this condition however it contains valuable substances, some of
which I extract by my Invention, and after they have been extracted I have rendered
the oxide of iron again fit for use in the said purification of gas.
In carrying out my said Invention I take. the said spent oxide, and place it in
suitable tanks, and by water, either cold or hot, I dissolve and wash out any com-
pounds of ammonia it may contain; this is needful for subsequent operations, but does
not of itself constitute any part of my Invention. I now turn the material on to a floor,
and let it drain until tolerably dry. I then take unslacked lime, equal in quantity
to one-half of the spent oxide, and slake it into a fine dry powder, and with this
dry powdered hydrate of lime I mix intimately the drained spent oxide, and place
the whole in tanks, preferably of iron, having each a false bottom, also of iron, such
false bottoms being provided with numerous small holes, and having a pipe (say, of
three inches diameter) arising from under the false bottoms of the tanks to the
surface, and through which water or solutions can be poured directly into the spaces
between the bottoms and false bottoms of the tanks. The tanks having been filled
with the mixture, water is poured through the said pipes until it rises, over the
material, and which water may be heated to 150° or 160° F., but should not be

page_text: nearer the boiling point. The liquid overflowing or drawn off may be used at once,
or passed into other tanks to strengthen it; in the former case it is run into a
reservoir until clear, and it is then run into precipitating vessels, and has added to
it a solution of perchloride of iron, with a slight excess of hydrochloric acid until no
more precipitation takes place. The precipitate is Prussian blue, which, after sub-
sidence, is washed by renewed waters, and is then either made into pulp blue or
dry Prussian blue, as is well known; or, after the said washing or subsidence, I
add to it a sufficient quantity of potash to decompose the Prussian blue, and the
solution so formed I boil up until it is ready to crystallize prussiate of potash. The
spent oxide having had all the prussiate of lime washed out is now, without
removing it from the iron tanks, covered with water, and submitted to boiling by
blowing steam into the spaces between the two bottoms. A dark solution of
sulphides of calcium is formed, and I continue to boil and run off until all is
extracted. This solution I run into another series of tanks. After settlement, and
when cold, I add to it hydrochloric acid until the liquor has a slightly acid reaction.
Sulphur nearly pure is now precipitated, and this having been washed, drained, and
dried, is fit for most of the purposes for which brimstone is used. The spent material
in the tanks is now drained and dried, and is fit for being again used in the purifi-
cation of gas.
Having thus described and ascertained the nature of my said Invention, and the
manner in which the same is to be performed, I desire it to be understood that I
claim as secured to me under the above in part recited Letters Patent, the treatment
of such spent oxide as aforesaid, substantially as described, for the purposes of
obtaining Prussian blue, or prussiate of potash and sulphur, and for again rendering
the said oxide fit for use in the purification of gas.
In witness whereof, I, the said Peter Spence, have hereunto set my hand and
seal, this Third day of May, in the year of our Lord One thousand eight
hundred and seventy-eight.