Improvements in the Method or Process of Treating or Utilising the Spent or Residual Liquid Formed in the Process of Cleaning Iron or Steel with Hydrochloric Acid.
Year: 1889

page_text: Date of Application, 4th Mar., 1889
Complete Specification Left, 4th Dec., 1889-Accepted, 4th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Method or Process of Treating or Utilising
the Spent or Residual Liquid Formed in the Process of Cleaning
Iron or Steel with Hydrochloric Acid.
I THOMAS BEALBY SAUNDERS, of the Firm of Saunders & Saunders, Cleckheaton,
in the County of York, Manufacturing Chemists, do hereby declare the nature of this
invention to be as follows:-
This invention relates to improvements in the process or method of utilising the
spent or residual liquid formed during the treatment of iron or steel with hydro-
chloric acid preparatory to the galvanising, tinning, drawing and other processes
requiring a clean surface, which liquid consists of a solution of chloride of iron and
hydrochloric acid. And the object of the invention is to recover or reproduce the
said acid and to also form sulphate of iron which may be further treated in the manner
hereinafter described.
The said waste or residual liquid is first neutralised by the addition of scrap iron to
convert the remaining hydrochloric acid into chloride of iron the now neutral solution
is evaporated in any convenient manner so as to leave the chloride of iron in a dry or
pasty state.
This solid chloride of iron is afterwards treated with sulphuric acid which decomposes
it and combining with the iron forms anhydrous sulphate of iron. Hydrochloric acid
is given off in a gaseous form and is collected and condensed in the ordinary manner.
The anhydrous sulphate of iron left may be converted into crystallised sulphate of iron
or copperas by the addition of water or be utilised for the production of nitrate of
iron.
Or the anhydrous sulphate of iron may be roasted or distilled to form oxide of iron,
the acid vapors given off being collected and condensed.
=
COMPLETE SPECIFICATION.
Improvements in the Method or Process of Treating or Utilising
the Spent or Residual Liquid Formed in the Process of Cleaning
Iron or Steel with Hydrochloric Acid.
1, THOMAS BEALBY SAUNDERS, of the Firm of Saunders & Saunders, Cleckheaton
in the County of York, Manufacturing Chemists, 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 relates to improvements in the process or method of utilising the
spent or residual liquid formed during the treatment of iron or steel with hydro-
chloric acid preparatory to the galvanising, tinning, drawing and other processes
requiring a clean surface, which liquid consists of a solution of chloride of iron and
hydrochloric acid. And the object of the invention is to recover or reproduce the
said acid and to also form sulphate of iron which may be further treated in the manner
hereinafter described:
The said waste or residual liquid is first neutralised by the addition of scrap iron to
convert the remaining hydrochloric acid into chloride of iron. The now neutral
solution is evaporated in any convenient manner so as to leave the chloride of iron in
a dry or pasty state.

page_text: This solid chloride of iron is afterwards treated with sulphuric acid which decom-
poses it and combining with the iron forms anhydrous sulphate of iron. Hydro-
chloric acid is driven off in a gaseous form and is collected and condensed in the
ordinary manner. The anhydrous sulphate of iron left may be converted into
crystallised sulphate of iron or copperas by the addition of water or be utilised for the
production of nitrate of iron.
Or the anhydrous sulphate of iron may be roasted or distilled to forin oxide of iron,
the acid vapors given off being collected and condensed.
To illustrate the manner in which I preferably carry out my invention reference is
made to the accompanying sheet of drawings.
The spent liquor is run into and collected in the tank A containing iron wire or
other scrap iron, and remains in such tank until it is thoroughly neutralised, and it is
then pumped into the raised cistern B. This neutralised liquor is allowed to flow
through the pipe C controlled by the valve D in sufficient quantity to fill the
evaporating pan E heated by the furnace F, and the contents of the pan are evaporated.
This operation is repeated until the pan E is approximately full of pasty residue from
the evaporating process consisting of chloride of iron. The passage G in the dome of
the pan, conveying the vapour given off during the evaporating process to the flue, is
now closed by a suitable damper, and the damper H separating the pan chamber J
from the chamber K of the blind roaster I is opened. At the same time the valve M
in the pipe N, communicating with the cistern 0 which contains a supply of
sulphuric acid is opened and a suitable quantity of such acid is allowed to flow into the
pan E. The action of the sulphuric acid decomposes the chloride of iron in the pan
liberating the hydrochloric acid which passes into the chamber K through the
passage R and into the condensing tower T where it is condensed in the usual
This is continued until the contents of the pan are approximately dry
and there is a danger of applying too great a heat in the pan. Then the contents
are withdrawn from the pan and spread upon the floor of the chamber K of the
blind roaster until thoroughly dry, which chamber is moderately heated by the
flues U and V leading from the furnace F, the damper W being opened to
regulate the heat of the roaster.
Inanner.
In this manner the conversion of the chloride of iron into anhydrous sulphate
of iron is continued in the chamber K until hydrochloric acid ceases to be given
off when the process is complete and the sulphate of iron is removed from the
chamber. In the meantime by closing the damper H a second pan of chloride of
iron may be in the course of preparation to be treated in the above described
manner with sulphuric acid, thus the whole process may be approximately con-
tinuous.
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 what I claim is :-
The complete method or process of treating or utilising the spent or residual
liquid formed in the process of cleaning iron or steel with hydrochloric acid con-
sisting in neutralising the liquid, reducing it by evaporation, and decomposing
it with sulphuric acid into hydrochloric acid and sulphate of iron, substantially as
herein shown and described and for the purpose specified.
Dated this 2nd day of December 1889.
DRACUP & NOWELL,
Bradford, Agents.