IMPROVEMENTS IN TREATING WASTE SUL- PHURIC ACID THAT HAS BEEN USED FOR PICKLING IRON PLATES AND OTHER ARTICLES OF IRON OR STEEL.” PROVISIONAL SPECIFICATION
Year: 1878

page_text: :
LETTERS PATENT to Robert Lavender, of Mold, in the County of Flint, and
Josiah Richards and David Williains, both of Pontypool, in the County of
Monmouth, for the Invention of "IMPROVEMENTS IN TREATING WASTE SUL-
PHURIC ACID THAT HAS BEEN USED FOR PICKLING IRON PLATES AND OTHER
ARTICLES OF IRON OR STEEL.”
PROVISIONAL SPECIFICATION left by the said Robert Lavender, Josiah
Richards, and David Williams at the Office of the Commissioners of Patents
on the 12th August 1878.
"
ROBERT LAVENDER, of Mold, in the County of Flint, and JOSIAH RICHARDS and
DAVID WILLIAMS, both of Pontypool, in the County of Monmouth. IMPROVE-
MENTS IN TREATING WASTE SULPHURIC ACID THAT HAS BEEN USED FOR PICKLING
IRON PLATES AND OTHER ARTICLES OF IRON OR STEEL."
This Invention has for its object improvements in treating waste sulphuric acid
that has been used for pickling iron plates and other articles of iron or steel.
At the present time sulphuric acid is largely used in the manufacture of tin and
terne plates for pickling the plates of iron previous to coating them with tin or
terne metal. Spent liquor so obtained is for most part either evaporated down
in open vessels to obtain copperás, or in some cases looked upon as a waste product
and allowed to run to waste, fouling the rivers or streams into which it is allowed
to run.
According to our Invention we distil the spent liquor until a dry residue of
anhydrous sulphate of iron is obtained. This dry residue we afterwards roast in
highly heated retorts, and the sulphuric acid driven off we condense and collect,
whilst the sulphurous fumes we lead into leaden chambers and utilize in the manu-
facture of sulphuric acid.
When the roasting is complete a residue of rouge remains in the retorts. This is
a valuable product for which there are many now used.
The distillation and roasting might, if desired, both be effected in the same closed
still,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Lavender, Josiah Richards, and David Williams in the Great
Seal Patent Office on the 11th February 1879.
ROBERT LAVENDER, of Mold, in the County of Flint, and JOSIAH RICHARDS and
DAVID WILLIAMS, both of Pontypool, in the County of Monmouth. "IMPROVE-
MENTS IN TREATING WASTE SULPHURIC ACID THAT HAS BEEN USED FOR PICKLING
IRON PLATES AND OTHER ARTICLES OF IRON OR STEEL."
This Invention has for its object improvements in treating waste sulphuric acid
that has been used for pickling iron plates and other articles of iron or steel.
At the present time sulphuric acid is largely used in the manufacture of tin and
terne plates for pickling the plates of iron previous to coating them with tin or
terne metal. Spent liquor so obtained is for the most part either evaporated down
in open vessels to obtain copperas, or in some cases looked upon as a waste product
and allowed to run to waste, fouling the rivers or streams into which it is allowed
to run.
According to our Invention we distil-the spent liquor to obtain a dry residue and
afterwards roast this residue in highly heated retorts to obtain sulphuric acid.
In carrying out our Invention we proceed as follows:-We take the spent liquor
that has been used for pickling the iron plates previously to their being tinned and
filter it. The filter we employ for this purpose is constructed of wood, either lined
with lead or otherwise. At the bottom of the vessel is a perforated false bottom,
upon which the bed of filtering material is to rest. We find it convenient to place
over the false bottom a layer of about one inch thick of unspun hemp, and upon
this a layer of sawdust, and then another layer of hemp. As the filtering pro-
gresses the sawdust deposited from the liquor is removed from time to time, as may be
necessary. The liquor passing from the filter is collected in a tank.
In order to distil the liquor, to drive off the water contained in it, we place the
liquer into a V shaped or other suitable vessel. We find that lead lined vessels
are the most suitable, or they may be of wood, but other suitable material might
be used. We then pass up through the liquor jets of superheated steam at a tempe-
rature, say, of about 600 to 700° Fahrenheit. The temperature of the liquor is
thereby raised and the water evaporated. We carry on this process until nearly
the whole of the water is expelled, and a residuum of what may be termed an-
hydrous sulphate of iron remains. This we take out of the pans when hot and
cast into moulds; when cold we crush it into a fine state.
Other methods than the one above described may be employed for distilling off
the water contained in the spent liquor; the way described is however very con-
venient for the purpose.
The powdered residuum we transfer into shallow fire-brick pans or pans of other
suitable substance, which are then put into retorts constructed of iron or fire-brick,
or in ovens provided with suitable ledges or shelves.
If retorts are used they may be placed in sets in a furnace in a similar manner
to what is practised in the manufacture of gas or the distillation of shale, and the
furnaces may be similarly constructed.
The vapours arising are conducted by means of pipes or flues during the process
of distillation into lead chambers. These vapours consist principally of sulphurous
fumes and acid. At the same time we insert into the retorts or ovens, vessels con-
taining nitrate of soda and sulphuric acid. The nitrous fumes thus given off pass
along with the sulphur fumes into the lead chamber, into which we introduce steam
jets in the same way as when making sulphuric acid in the manner now generally
employed in this country.
The residuum left in the retorts or ovens being red oxide of iron, is prepared
as a pigment used for paint, or prepared for polishing metal, glass, and other.
substances

page_text: Having thus described the nature of our Invention, and the manner of performing
the same, we would have it understood that we claim as our improvements in
treating waste sulphuric acid that has been used for pickling iron plates and other
articles of iron or steel, the distilling the spent liquor to drive off water from it,
and afterwards roasting the residue to obtain sulphuric acid and red oxide of iron,
substantially as herein-before described.
In witness whereof, I, the said Robert Lavender, have hereunto set my hand
and seal, this Eighth day of February, in the year of our Lord One thou-
sand eight hundred and seventy-nine.
February 8th, 1879.