Improvements in the Recovery of Hydrochloric Acid and Ferric Oxide from Ferrous Chloride.
Year: 1892

page_text: Date of Application, 19th Feb., 1892
Complete Specification Left, 18th Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Recovery of Hydrochloric Acid and Ferric
Oxide from Ferrous Chloride.
I, MICHEL NICHOLAS D'ANDRIA of Birch Villa Windsor Road Levenshulme
in the County of Lancaster Manufacturing Chemist do hereby declare the nature
of this invention to be as follows:-
My invention is based on the fact that oxide of magnesia is capable of decomposing
ferrous chloride into ferrous oxide and chloride of magnesia the latter being
comparatively easily decomposed into hydrochloric acid and oxide of magnesia
thus
1) FeCl2 + MgO + HO :
UHT JN (6
MoO
= FeO + MgCl2 + H₂O
2 HCl.
3) FeSO4 + MgO FeO + MgSO..
=
In carrying out these processes I proceed as follows: 200 parts of crystallized
ferrous chloride are intimately mixed with 50 parts of oxide of magnesia. This
mixture is subjected to temperatures at or above red heat in clay retorts,
which latter are connected with any one of the well known acid gas condensing
arrangements and in which the hydrochloric acid developed in the retorts is
condensed. The speed with which the hydrochloric acid is given off is greatly
increased by passing over the mixture in the retorts a small current of steam.
As soon as the hydrochloric acid is given off a current of hot air is introduced
into the retort, and in this manner the ferrous oxide is converted into ferric oxide. If
this is completed the retort is discharged and filled with a fresh quantity of the first
described mixture. The mixture of ferric oxide and magnesia oxide is treated with
hydrochloric acid or sulphuric acid whereby respectively chloride or sulphate of
magnesia are obtained which by filtration may be separated from the ferric oxide.
If carbonate of magnesia instead of oxide of magnesia be employed, the process
is worked in exactly the same manner as above described a mixture of 200 parts of
ferrous chloride and 100 parts of carbonate of magnesia being used.
If sulphate of magnesia is employed the retorts are charged with a mixture of
200 parts of ferrous chloride and 250 parts of sulphate of magnesia, and while being
treated, the mixture is subjected to either alternative or simultaneous currents of
steam and air. All the hydrochloric acid being driven off, the retorts are
discharged, and on treating the discharge with water all the magnesium sulphate
originally employed is obtained in solution, ferric oxide remaining behind. In this
way one and the same quantity of magnesium sulphate may be employed over and
over again.

page_text: =
2) MgCl + H₂O
3) FeCl + MgCO,
MgO + 2 HCI
=
FeO + MgCl, + CO,.
I have further found that a similar decomposition may be obtained by using
sulphate of magnesium, the chemical reaction proceeds then, on the following
lines:
4) FeCl2 + MgSO
4
FeSO + MgCl₂
(5 FeSO4 + MgCl2 + H₂O
6) FeSO + MgO
FeSO4 + MgO + 2HC1
FeO + MgSO₁.
It will be seen that eventually the originally employed sulphate of magnesium is
recovered and can be used over again.
In carrying out this process, it must of course be taken into account that by the
evaporation of the acid solutions of ferrous chloride as obtained under the name of
"waste pickles" in the galvanizing and cleaning of sheet iron, wire etc. a great
quantity of hydrochloric acid would be lost. To avoid this I neutralize these
liquors previous to evaporation by adding to them iron scraps in some suitable form,
but I find it preferable to add to them such quantities of carbonate or oxide of
magnesium as may be required to exactly neutralize any free hydrochloric acid
present, whereafter I proceed with the evaporation of the neutral liquors.
I then proceed as follows:
I mix 200 parts of crystallized ferrous chloride or its equivalent intimately,
with 50 parts of oxide of magnesium.
This mixture is subjected to temperatures at or above red heat, preferably in clay
retorts which latter are connected with any one of the well known hydrochloric acid
gas condensing arrangements, and in which the hydrochloric acid developed in the
retorts is condensed.
The speed with which the hydrochloric acid is given off is greatly increased by
passing over the mixture in the retorts a small current of steam.
As soon as the hydrochloric acid is expelled, a current of hot air is introduced
into the retort, and in this manner the ferrous oxide is converted into ferric oxide.
When this is completed, the retort is discharged and filled with a fresh quantity of
the first described mixture. The mixture of ferric oxide and magnesium oxide is
treated with hydrochloric or sulphuric acid whereby respectively chloride or
sulphate of magnesium are obtained, which by filtration may be separated from the
*ferric oxide.
If carbonate of magnesium instead of oxide of magnesium be employed, the
process is worked in exactly the same, manner as above described, a mixture of
200 parts of ferrois chloride or its equivalent and 100 parts of carbonate of
maguesium being used.

page_text: If sulphate of magnesium is employed the retorts are charged with a mixture of
200 parts of ferrous chloride or its equivalent and 250 parts of sulphate of
magnesium, and while being heated, the mixture is subjected to either alternative
or simultaneous currents of steam and air. All the hydrochloric acid being driven
off, the retorts are discharged, and on treating the discharge with water, all the
magnesium sulphate originally employed is obtained in solution ferric oxide
remaining behind. (It is of course understood that when the acid solutions of
ferrous chloride above referred to, have been neutralized with magnesium oxide or
magnesium carbonate, some oxide of magnesium is left with this ferric oxide.)
In this way, one and the same quantity of magnesium sulphate may be employed
over and over again.
The furnaces to be employed by preference are either ordinary reverberation
muffle furnaces, or reverberatory gas furnaces, or muffle furnaces constructed on
what is known the blow-pipe system. The latter are arranged in such a manner,
that a triplet jet is introduced into the muffle fronts, the centre jet being used to
feed the necessary steam into the muffle, while through the concentric jets, the
generator gas and air in the proportions required for complete combustion, are
introduced respectively.
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 that what I
claim is
The recovery of hydrochloric acid and ferric oxide from ferrous chloride by
treating the latter with magnesium oxide, magnesium carbonate, or magnesium
sulphate, also employing either throughout or at specified stages of the treating
process either alternative or simultaneous currents of steam and air.
Dated this 17th day of November 1892.
M. N. D'ANDRIA.