Process for Obtaining Zinc Solutions Free from Iron and Manganese Compounds.
Year: 1899

page_text: Date of Application, 1st Nov., 1999-Accepted, 9th Dec., 1899
COMPLETE SPECIFICATION.
Process for Obtaining Zinc Solutions Free from Iron and Manganese
Compounds.
I, FRIEDRICH AUGUST GASCH, of 243A, Fabrikhof, Honningen on the Rhine,
Germany, 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 a process for preparing zinc solutions free from iron
and manganese compounds and at the same time making zinciferous spent
pyrites profitably useful.
Hitherto the purification of zinc solutions has been effected by adding to the
moderately strong solution, chloride of lime solution until all the iron and man-
ganese are precipitated. The precipitate is so bulky that mere settling is of no
use and a filter press has to be employed. Moreover, the precipitate carries with
it much zinc which is thereby lost.
By the present invention the spent pyrites is ground to fragments of about 1
to 2 mm. diameter and intimately mixed with the quantity of sulphuric acid,
of specific gravity 60° Beaumé, equivalent to the zinc present. This mixture is
allowed to remain in heaps for 1 to 2 days and the product is heated for 5 to 6
hours in reverberatory furnace or a muffle furnace at a low red heat. After
it has been withdrawn from the furnace and while it is still nearly red hot, the
material is mixed with a certain proportion of a mixture of Chili saltpetre or
another suitable oxidising agent and caustic lime. By this means the ferrous
and manganese compounds present are peroxidised and remain undissolved, being
precipitated by the caustic lime, when the material is leached with hot water.
The following equations represent this oxidation and precipitation :-
Concentrated sulphuric acid is used in this process because it attacks the iron
of the spent pyrites but little, whereas the dilute acid which has been used in
other processes easily dissolves the iron.
The process (1) enables zinciferous spent pyrites to be purified until it con-
tains less than 1 per cent. of zinc, so that it is saleable as an iron ore, (2) doubles
the yield of the furnaces, thus reducing the cost for coal and labour, and (3)
yields directly a zinc solution free from iron and manganese compounds such as is
applicable in some manufacturing processes without further purification.
Instead of concentrated sulphuric acid alone this acid mixed with common salt
or a mixture of ferrous chloride and concentrated hydrochloric acid may be used.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
Process for obtaining solutions of zinç free from iron and manganese compounds

page_text: by treating zinciferous spent pyrites with concentrated sulphuric acid, with or
without the addition of common salt, or with concentrated hydrochloric acid and
ferrous chloride, then roasting the product of this treatment and mixing it, while
it is still red-hot, with a suitable oxidising agent, such as saltpetre, and caustic
lime and finally leaching the mixture with water, substantially as described.
Dated this 1st day of November 1899.
ABEL & IMRAY,
Agents for the Applicant.