Improvements in the Utilization of Waste or Spent Acid Pickle from Galvanizing Works or other Works where Iron is Treated by Acid, and in the Treatment (for the Recovery or Obtainment of Chlorine) of other Products Containing Chlorine.
Year: 1894

page_text: Date of Application, 21st Dec., 1894
Complete Specification Left, -20th Sept., 1895-Accepted, 9th Nov., 1895
Improvements in the Utilization of Waste or Spent Acid Pickle
from Galvanizing Works or other Works where Iron is Treated
by Acid, and in the Treatment (for the Recovery or Obtainment
of Chlorine) of other Products Containing Chlorine.
I, THOMAS PARKER, of Manor House, Tettenhall near Wolverhampton in the
County of Stafford, Engineer, do hereby declare the nature of this invention to
be as follows:-
"This invention, as it relates to the utilization of waste or spent acid pickle
from galvanizing works and other works (such as tinplate works) where iron is
treated by acid, has for its object, when the pickling acid is hydrochloric, chiefly
the obtainment therefrom of chlorine, and when the pickling acid is sulphuric,
chiefly the obtainment, by means thereof, of chlorine from chlorine compounds,
such as chloride of calcium.
When the pickling acid is hydrochloric, I treat the waste pickle with scrap
iron or oxide of iron to reduce the free acid and ferric chloride to the state of ferrous
chloride. I then drive off the water; for which purpose the evaporation is effected
in a covered vessel to exclude the air and thus avoid the oxidation of the ferrous
chloride. The dried ferrous chloride (which includes the ferrous chloride
originally in the waste pickle as well as that which results from the treatment with
scrap iron or oxide of iron) is then removed to a furnace where it is heated to a
dull red beat and exposed while heated to a current of air, with the result that
chlorine is given off leaving a residue of oxide of iron. The chlorine may then be
treated as required (being washed, if desired, in a tower) and may be utilized for
any purpose for which it may be required.
When the pickling acid is sulphuric, I treat the sulphate of iron in the waste
pickle with chloride of calcium or common salt, preferably the former, with the
result that ferrous chloride and sulphate of calcium or of soda as the case may be,
are formed. The ferrous chloride is then treated in the manner above described,
with the result that chlorine is given off.
Chlorine may also be obtained, according to this invention, from chloride of
calcium, such as that forming a waste or bye product resulting from the manu-
facture of carbonate of soda by the ammonia process. For this purpose, iron
pyrites may by roasting be made to form a source of sulphate of iron. The
chloride of calcium is treated with the sulphate of iron, and from the resulting
ferrous chloride chlorine is obtained in the manner ahove described. Chlorine
may be similarly obtained also from chloride of sodium and chloride of magnesium.
Dated this 20th day of December 1894.

page_text: COMPLETE SPECIFICATION.
Improvements in the Utilization of Waste or Spent Acid Pickle
from Galvanizing Works or other Works where Iron is Treated
by Acid, and in the Treatment (for the Recovery or Obtainment
of Chlorine) of other Products Containing Chlorine.
I, THOMAS PARKER, of Manor House, Tettenhall near Wolverhampton in the
County of Stafford, Engineer, do hereby declare the nature of this 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, as it relates to the utilization of waste or spent acid pickle from
galvanizing works and other works (such as tinplate works) where iron is treated
by acid, has for its object, when the pickling acid is hydrochloric, chiefly the
obtainment therefrom of chlorine, and when the pickling acid is sulphuric, chiefly
the obtainment, by means thereof, of chlorine from chlorine compounds, such as
chloride of calcium.
When the pickling acid is hydrochloric, I add to the waste pickle iron,
preferably scrap iron in small pieces, and most conveniently small wrought scrap
in the form of turnings or the like, or sheet iron scrap, to take up or neutralise the
free acid by forming therewith ferrous chloride. I then drive off the water by
evaporation in a covered vessel to exclude the air and thus avoid the oxidation of
the ferrous chloride. The dried ferrous chloride (which includes the ferrous
chloride originally in the waste pickle, as well as that which has resulted from
the action of the free acid upon the iron added to the waste pickle) is then
removed to a furnace where it is heated to a dull red heat and exposed while
heated to a current of air (which may with advantage be heated), with the result
that chlorine is given off, leaving a residue of oxide of iron. The chlorine may
then be treated as required (being washed, if desired, in a tower), and may be
utilized for any purpose for which it may be required; and the oxide of iron may
be utilized in the manufacture of paint, or for other purpose for which it may be
suitable.
When the pickling acid is sulphuric, I treat the sulphate of iron in the waste
pickle with chloride of calcium, or of magnesium, or common salt (preferably the
first mentioned), with the result that ferrous chloride and sulphate of calcium, or
of magnesium, or of sodium, as the case may be, are formed.
The liquor containing the ferrous chloride in solution is evaporated in the
manner above described and the dry ferrous chloride treated in the manner
of treating the dry ferrous chloride in the hydrochloric acid process above
described, with corresponding result. If the sulphate resulting from the treatment
of the sulphate of iron in the liquor with a chloride is of calcium it is precipitated,
being insoluble, and is extracted from the liquor prior to the evaporation thereof;
and if the sulphate resulting from such treatment is of magnesium or sodium,
crystals thereof form as the evaporation proceeds, and these or a considerable
proportion of them may be fished out of the solution. The presence of sulphate
of magnesium or of sodium, however, with the dry ferrous chloride even in
considerable quantity, does not interfere with the subsequent process for the
recovery of the chlorine.
Chlorine may also be obtained, according to this invention, from chloride of
calcium, such as that forming a waste or bye-product resulting from the manu-
facture of carbonate of soda by the ammonia process, by treating the chloride of
calcium with sulphate of iron, other than that contained in waste acid pickle, and
obtaining chlorine from the resulting ferrous chloride in the manner above
described.

page_text: Chlorine may be similarly obtained also from chloride of sodium and chloride
of magnesium. Iron pyrites may by roasting be made to form a source of sulphate
of iron for utilization in this process.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is-
1. The treatment of waste or spent hydrochloric acid pickle from galvanizing
works or other works where iron is treated by hydrochloric acid, which consists in
taking up or neutralising the free acid by the use of iron which forms therewith
ferrous chloride, then evaporating the water in a covered vessel, and finally
heating, while exposed to a current of air, the dried ferrous chloride to drive off the
chlorine, substantially as described.
2. The treatment of waste or spent sulphuric acid pickle from galvanizing
works, or other works where iron is treated by sulphuric acid, which consists in
treating the waste or spent pickle with chloride of calcium, or of magnesium, or
common salt, for the formation of ferrous chloride and sulphate of calcium, or of
magnesium, or of sodium, then extracting the sulphate and evaporating the water
in a closed vessel and heating while exposed to a current of air the resulting dried
ferrous chloride to drive off the chlorine, substantially as described.
3. Treating chloride of calcium, or of sodium, or of magnesium (for the
obtainment of chlorine) with sulphate of iron whereby ferrous chloride is
produced, then extracting the sulphate and evaporating the water in a closed
vessel, and heating, while exposed to a current of air, the resulting dried ferrous
chloride to drive off the chlorine, substantially as described.
Dated this 18th day of Septemba 1905
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicant.