Improvements in the Treatment of Waste Liquors from Metallurgical Processes to Obtain Sulphurous or Sulphuric Acid and Zinc.
Year: 1891

page_text: Date of Application, 11th June, 1891
Complete Specification Left, 10th Mar., 1892-Accepted, 30th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Waste Liquors from Metallurgical
Processes to Obtain Sulphurous or Sulphuric Acid and Zinc.
I, ALLAN TWISLETON HALL, F.C.S., of Inglebank, Newland, Hull, do hereby
declare the nature of this invention to be as follows:-
I add to the waste liquor resulting from the extraction of copper by the wet
process (which contains salts of iron and zinc particularly chloride of iron and
chloride of zinc) a solution obtained by boiling alkali waste (polysulphide of
calcium) with lime. A black precipitate results containing sulphide of iron and
sulphide of zinc. This precipitate is burnt in an ordinary furnace and sulphurous
acid is given off which may be employed for the manufacture of sulphuric acid in
the usual way. The residue in the furnace containing oxide of iron and oxide of
zinc is smelted to obtain metallic zinc. The iron may be partially precipitated
from the waste copper liquor before it is treated as above described.
Soda ash or other alkaline material may be substituted for the lime and sulphides
of the alkaline earths for the alkali waste and lime.
The process is applicable to other liquors containing salts of zinc.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Waste Liquors from Metallurgical
Processes to Obtain Sulphurous or Sulphuric Acid and Zinc.
I, ALLAN TWISLETON HALL, F.C.S., of Inglebank, Newland, Hull, 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:—
I add to the waste liquor resulting from the extraction of copper by the wet
process (which contains salts of iron and zinc particularly chloride of iron and
chloride of zinc) a solution obtained by boiling alkali waste (polysulphides of
calcium) with lime. A black precipitate results containing sulphide of iron
and sulphide of zinc. This precipitate is burnt in an ordinary furnace and
sulphurous acid is given off which may be employed for the manufacture of sulphuric
acid in the usual way. The residue in the furnace containing oxide of iron and
oxide of zinc is smelted to obtain metallic zinc. The iron should be partially
precipitated from the waste copper liquor before it is treated as above described.
Soda ash or other alkaline material may be substituted for the lime and sulphides
of the alkaline earths for the alkaline waste and lime.
The process is applicable to other liquors containing salts of zine.
The method of procedure is as follows:-The greater part of the iron is first
precipitated from the waste liquor by means of lime in the ordinary way and to
each gallon of liquor (which usually contains about to 2½ ozs. of metallic zinc)
about a or of a pound of prepared alkali waste is added in the form of a cream
or solution and the mixture is then agitated and boiled for about 4 or 5 hours. It
is then allowed to stand and the precipitate is removed and treated as above
described.
The alkali waste is prepared by being ground with about 1 part of its weight of
lime or part of its weight of soda ash, the mixture being afterwards boiled.

page_text: Unprepared alkali waste will work but not so well.
In place of burning the precipitate it may be simply dried and smelted or it may
be used as a pigment.
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-
1. The process of obtaining sulphide of zinc from waste liquors containing salts
of zinc by precipitating with alkali waste or the sulphides of the alkaline earths
substantially as described.
2. The process of obtaining sulphide of zinc from waste liquors containing salts
of zinc by precipitating with a mixture of alkali waste and lime or other alkaline
material substantially as described.
3. The process of obtaining sulphide of zinc from waste liquors containing salts
of zinc and iron by first precipitating iron with lime and afterwards precipitating
the sulphide of zinc with alkali waste or the sulphides of the alkaline earths
substantially as described.
4. The process of obtaining sulphide of zinc from waste liquors containing salts
of zinc and iron by first precipitating iron with lime and afterwards precipitating
the sulphide of zinc with a mixture of alkali waste and lime or other alkaline material
substantially as described.
5. The treatment of waste liquors from metallurgical processes to obtain sulphurous
acid or sulphuric acid and zinc substantially as described.
Dated this 7th day of March 1892.
Witness to the above signature-
G. CARR ROBINSON.
ALLAN T. HALL.