IMPROVEMENTS IN AND RELATING TO THE TREATMENT AND UTILISATION OF THE SPENT PICKLE AFTER USE FOR CLEANING IRON
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, THOMAS BAYLEY of 7 Broad St. Corner, Birmingham, Analytical Chemist
do hereby declare the nature of my invention for IMPROVEMENTS IN AND RELATING
TO THE TREATMENT AND UTILISATION OF THE SPENT PICKLE AFTER USE FOR
CLEANING IRON to be as follows:-
My invention consists in a method of so treating spent pickle as to obtain
oxides of iron of various colours, consistencios, degrees of fineness, and other
physical properties, for useful employment in the arts and in commerce.
The spent liquids containing soluble salts of iron are mixed either in a hot
or cold condition with milk of lime in sufficient quantity to precipitate all the
iron.
The resulting precipitated hydrated oxides of iron are then separated from the
liquid by the use of a filter press or otherwise, washed to remove impurities and
converted into peroxide of iron. I prefer to so convert them by roasting in a
suitable furnace in a current of air. The red oxide is then ground and levigated
and otherwise prepared so as to admit of being used for ordinary purposes, namely
for the polishing and colouring of metals and other substances, for use as
pigments, etc.
In order to obtain the oxides in a state of purity I prefer to operate upon the
pickle resulting from the employment of muriatic (hydrochloric) acid; if sulphuric
acid pickle be used oxide of iron mixed with sulphate of calcium is obtained.
If it is desired to remove the sulphuric acid from pickle before treatment with
lime the solution of chloride of calcium resulting from the addition of milk of
lime to hydrochloric acid pickle may be employed. The solution of chloride of
calcium is added in sufficient quantity and the sulphate of calcium separated by
filtration or subsidence.

page_text: COMPLETE SPECIFICATION.
I, THOMAS BAYLEY of 7 Broad Street Corner Birmingham Analytical Chemist
do hereby declare the nature of the said invention for "IMPROVEMENTS IN AND
RELATING TO THE TREATMENT AND UTILIZATION OF THE SPENT PICKLE AFTER USE
FOR CLEANING IRON" and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement that is
to say:
My invention consists in a method of so treating spent pickle as to obtain oxides
of iron of various colours, consistencies degrees of fineness and other physical
properties for useful employment in the arts and in commerce.
The spent liquids containing soluble salts of iron are mixed either in a hot
or cold condition with milk of lime in sufficient quantity to precipitate all the
iron.
The resulting precipitated hydrated oxides of iron are then separated from
the liquid by the use of a filter press or otherwise washed to remove impurities
and converted into per-oxide of iron. I convert them by roasting in a suitable
furnace in a current of air. The red oxide is then ground and levigated and
otherwise prepared so as to admit of being used for ordinary purposes, as for
the polishing and colouring of metals and other such substances for use as
pigments or paints and such like purpose. In order to obtain the oxides in a
state of purity, I prefer to operate upon the pickle resulting from the employment
of muriatic (hydrochloric) acid if sulphuric acid pickle be used, oxide of iron
mixed with sulphate of lime is obtained. Before treatment of such sulphuric acid
pickle with lime the solution of chloride of calcium resulting from the addition of
milk of lime to hydrochloric acid pickle may be employed to remove the
sulphuric acid.
The solution of chloride of calcium is added in sufficient quantity and the
sulphate of calcium is separated by filtration or otherwise.
The following is a more detailed mode of operating upon the pickle resulting
from the cleaning of iron with muriatic acid:-The pickle is placed in a suitable
vessel sufficient space being left for the milk of lime which has to be subse-
quently added A sufficient quantity of quick lime is then placed in another vessel
and is slacked with water. To the slacked lime water is now added until a cream
of lime is obtained. This cream is kept in a state of moderate agitation by
stirring and is passed by "means of a trough or pipe into the pickle. Any
lumps of lime or floating or other suspended particles of large size are separated
by sieving. The pickle and lime are well stirred during the admixture and care is
taken that the lime is not added in excess. It is even better to leave a small
quantity of iron salt unacted upon than to use an excess of lime. The milk of
lime may be partially or wholly replaced by such an equivalent as yellow liquor
which is produced by the lixivation of alkali-waste and contains certain sulphur
compounds of calcium or lime Such yellow liquors are used in the same way as

page_text: the cream of lime. In order to prevent the escape of sulphuretted hydrogen when
employing yellow liquor it is preferable to use as much lime as will precipitate half
of the pickle and subsequently to add the yellow liquor in quantity sufficient to
precipitate the remaining half. The pickle and lime may be mixed either in a hot
or cold condition and the free acid in the pickle may be removed as a preliminary
operation by the action of scrap iron. If this be not employed carbonate of lime
may be used in conjunction with the lime. The precipitate is separated from the
liquid by means of a "Johnsons" or other filter press or by any form of filter or
equivalent and the salts in the solution are washed out of the precipitate either by
decantation or in the press. The cakes are then transferred to the furnace and
roasted in a current of air until the required shade of colour is obtained. The oxide
so produced is subsequently ground and levigated and used for various purposes
such as those herein before mentioned.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
The improvements in and relating to the treatment and utilization of spent
pickle by the action of lime or yellow liquor so as to obtain the precipitate which
is afterwards treated by filtration or other equivalents and formed into pigments or
other suitable states by furnacing grinding and levigating substantially as herein
Bet forth.