An Improved Process for Recovering Valuable Substances from the Mother Liquor Resulting from Treatment of Copper Ores.
Year: 1889

page_text: Date of Application, 30th Aug., 1889
Complete Specification Left, 30th May, 1890-Accepted, 12th July, 1890
PROVISIONAL SPECIFICATION.
An Improved Process for Recovering Valuable Substances from the
Mother Liquor Resulting from Treatment of Copper Ores.
I, EDMOND DE CUYPER of Peronnes-lez-Binche in the Kingdom of Belgium,
Engineer, do hereby declare the nature of this invention to be as follows:-
This
This invention relates to a process for recovering valuable substances from the
mother liquor which results from the treatment of copper ores by chlorination.
liquor contains, amongst other substances, sulphate and chloride of soda, chloride
of zinc, and chloride of iron. The improved process has more especially for its
object to extract separately the soda, iron and zinc in a state in which they are adapted
for commercial purposes.
Heretofore the zine has not been separated on a large
scale from the iron, because the reagents employed precipitate at the same time the
compounds of iron and the compounds of zinc. For this reason I dispense with the
use of chemical reagents for effecting the separation of the zinc and the iron, and base
the said process upon the evaporation of the abovementioned mother liquor and the
calcination of the residue in the presence of air.
The process comprises five distinct operations, viz. :-(1) the concentration or
evaporation of the liquor to a pasty consistency (2) the calcination of this pasty
material (3) the separation of the iron from the other substances by dissolution and
washing (4) the obtention of the zinc by precipitation and (5) the transformation of
the sodic product which is in solution in the said liquor.
The evaporation of large quantities of liquid containing the above mentioned salts
is a costly operation if carried out in the ordinary way. For the purpose of rendering
the concentration more economical I employ a furnace, which consists of one or more
Into these chambers
evaporating chambers arranged in succession to one another.
the liquid is introduced and set in motion and which is divided by any suitable agitator,
such as a shaft provided with arms or vanes, which is rotated at a certain velocity.
The gaseous products of combustion from a gas furnace traverse the divided liquid
thus divided and cause considerable evaporation which reaches and even exceeds ten
kilogrammes of water per kilogramme of coal burnt.
In this partial evaporation the liquor holds ferrous chloride in solution. Under the
action of heat a precipitate of ferric hydrate is produced which is afterwards dissolved
by the aid of chloride of soda which is in the solution.
The ferrous chloride is transformed by the heat into a hydrochloric solution of
ferric hydrate, which is a step towards the decomposition of this ferrons chloride
into hydrochloric acid and ferric oxide.
In order to effect the calcination of the pasty material obtained the oxychloride
of iron is decomposed into hydrochloric acid and chlorine which is dissolved, and
ferric oxide which remains in the material in fusion.
The chloride of zinc is partly decomposed, hydrochloric acid and chlorine being
formed when the vapours have disappeared; the oxide of zinc remains combined with
the chloride of zinc, forming soluble oxychloride of zinc. This calcination must be
effected at a temperature below red heat, in order to obviate the sublimation of certain
parts of chloride of zinc.
From this calcination results the formation of the hydrochloric acid and chlorine
and a melted material which becomes concrete by cooling. The brownish material
thus obtained is composed of ferric oxide which is insoluble in water, and oxychloride
of zinc, sodium sulphate and sodium chloride, which are all three soluble in
water.
By dissolution and washing the aforesaid insoluble ferric oxide is then separated
from the aforesaid three soluble substances.

page_text: The ferric oxide obtained in this operation is of a reddish brown colour in a crystal-
lized state. It is pulverized with facility after desiccation.
By next treating the liquor which is left after the said dissolving and washing
operation with dissolved carbonate of soda, I form white and quite pure carbonate of
zinc and chloride of soda which remains in solution in the liquor.
I now add a sufficient quantity of sulphuric acid to transform all the chloride into
sulphate and concentrate the liquor which contains all the sulphate of soda. After the
cooling I obtain sulphate which is found to be very pure. In this operation there
is an abundant disengagement of hydrochloric acid resulting from the decomposition
of the chloride of soda and its transformation into sulphate.
It will be observed that in the course of the improved process the following substances
are recovered from the above-mentioned mother liquor, that is to say ferric oxide;
hydrochloric acid and chlorine; carbonate of zinc; and sulphate of soda.
Instead of as a carbonate the zinc may be extracted in the state of sulphide, by
employing sodium sulphide in lieu of sodium carbonate for the precipitation in the
aforesaid fourth operation.
In the fifth operation, carbonate of soda may be produced by treating the liquor
containing a mixture of sulphate of soda and chloride of soda with bicarbonate of
ammonia.
Dated this 30th dow of Anaust 1980.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Process for Recovering Valuable Substances from the
Mother Liquor Resulting from Treatment of Copper Ores.
I, EDMOND DE CUYPER of Peronnes-lez-Binche in the Kingdom of Belgium,
Engineer, 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 recovering valuable substances from the
mother liquor which results from the treatment of copper ores by chlorination.
This liquor contains amongst other substances sulphate and chloride of soda, chloride
of zinc, and chloride of iron. The improved process has more especially for its object
to extract separately the soda, iron and zinc in a state in which they are adapted for
commercial purposes. Heretofore the zinc has not been separated on a large scale
from the iron, because the reagents employed precipitate at the same time the com-
pounds of iron and the compounds of zinc."
For this reason I dispense with the use of chemical reagents for effecting the
separation of the zinc and the iron, and base the said process upon the evaporation
of the abovementioned mother liquor and the calcination of the residue in the
presence of air.
The process comprises five distinct operations, viz. :-(1) the concentration or
evaporation of the liquor to a pasty consistency; (2) the calcination of this pasty
material; (3) the separation of the iron from the other substances by dissolution and
washing; (4) the obtention of the zinc by precipitation, and (5) the transformation
of the sodic product which is in solution in the said liquor.
The evaporation of large quantities of liquid containing the abovementioned salts
is a costly operation if carried out in the ordinary way.
For the purpose of rendering the concentration more economical I employ a
furnace which consists of one or more evaporating chambers arranged in succession
to one another. Into these chambers the liquid is introduced and set in motion and
it is divided by any suitable agitator, such as a shaft provided with arms or vanes,
which is rotated at a certain velocity. The gaseous products of combustion from a

page_text: as-furnace traverse the liquid thus divided and cause considerable evaporation
hich reaches and even exceeds ten kilogrammes of water per kilogramme of coal
urnt.
A furnace constructed for this evaporation is represented in the accompanying
Figure 1 is a transverse section of the furnace on the line A—B. Fig. 2.
Figure 2 is an upper view.
Figure 3 shows a longitudinal and cross section of the agitator.
Figure 4 is a longitudinal section and
Figure 5 a transverse section of the furnace.
As represented in Figures 1 and 2 the liquid under the pressure of a column of
some metres passes into two pipes A which are perforated on their upper sides.
Opposite each hole is a small blast pipe provided on a parallel pipe B into which
hot air is forced. The object of this compressed hot air is to favour the outflow
of the liquid from the pipe A in such a manner that instead of obtaining a vertical
jet the outflowing liquid is sprayed or atomized thereby filling the basin of the
furnace in the form of vapour. Such pipes A B are arranged on each side of
the furnace in order to cause as uniform a formation of vapour as possible in the
furnace. When use is more especially made of water containing acid it is preferable
to employ earthen or stone ware pipes.
The agitation of the liquid to be introduced into the evaporating furnace is
effected by the arms or vanes S of the agitator, and these are set in rotation from
the outside by the shaft W. But in order that the shaft shall not be injuriously
affected by the acids and the heat it is made of a square iron bar covered out-
side with stone-ware plates, which are fixed by cement so that the liquid cannot come
in contact with the iron.
The agitator arranged in this manner rotates in a trough of suitable construction
which is arranged above the furnace and contains the liquid.
By the contact of the gases of combustion in the furnace with the liquid trans-
formed into vapour the former produces the aforesaid great effect as regards the
evaporation.
The coal may be burnt in any suitably constructed hearth and placed under the
action of a current of hot air before the gases of combustion enter the furnace
basin, as clearly indicated in Figures 4 and 5. The air becomes heated in the
channels a a in the top wall of the hearth and leaves the said channels at C where
it mixes with the products of combustion and transforms the whole into hot gases
which pass through the atmosphere of vapour in the basin of the furnace and escape
into the chimney.
In this partial evaporation the liquor holds ferrous chloride in solution. Under
the action of heat a precipitate of ferric hydrate is produced which is afterwards
dissolved by the aid of chloride of soda which is in the solution.
The ferrous chloride is transformed by the heat into a hydrochloric solution of
ferric hydrate, which is a step towards the decomposition of this ferrous chloride into
hydrochloric acid and ferric oxide.
In order to effect the calcination of the pasty material obtained the oxychloride of
iron is decomposed into hydrochloric acid and chlorine which is dissolved and ferric
oxide which remains in the material in fusion.
The chloride of zinc is partly decomposed, hydrochloric acid and chlorine being
formed when the vapours have disappeared, the oxide of zinc remains combined with
the chloride of zinc, forming soluble oxychloride of zinc. This calcination must be
effected at a temperature below red heat, in order to obviate the sublimation of
certain parts of chloride of zinc.
From this calcination results the formation of the hydrochloric acid and chlorine
and a melted material which becomes concrete by cooling. The brownish material
thus obtained is composed of ferric oxide which is insoluble in water, and oxy-
chloride of zinc, sodium sulphate and sodium chloride, which are all three soluble
in water.

page_text: By dissolution and washing the aforesaid insoluble ferric oxide is then separated
from the aforesaid three soluble substances.
The ferric oxide obtained in this operation is of a reddish brown colour in a
crystallized state. It is pulverized with facility after desiccation.
By next treating the liquor which is left after the said dissolving and washing
operation with dissolved carbonate of soda, I form white and quite pure carbonate of
zinc and chloride of soda which remains in solution in the liquor.
I now add a sufficient quantity of sulphuric acid to transform all the chloride
into sulphate and concentrate the liquor which contains all the sulphate of soda. After
the cooling I obtain sulphate which is found to be very pure. In this operation there
is an abundant disengagement of hydrochloric acid resulting from the decomposition
of the chloride of soda and its transformation into sulphate.
It will be observed that in the course of the improved process the following sub-
stances are recovered from the above-mentioned mother liquor that is to say :-ferric
oxide; hydrochloric acid and chlorine; carbonate of zinc; and sulphate of soda.
Instead of a carbonate the zine may be extracted in the state of sulphide, by
employing sodium sulphide in lieu of sodium carbonate for the precipitation.
In the transformation of the chloride of soda into sulphate, and the crystallization of
the latter, carbonate of soda may be produced by treating the liquor containing a
mixture of sulphate of soda and chloride of soda with bicarbonate of ammonia.
In the concentration of the mother liquor, instead of concentrating the liquor to
pasty constency I may discontinue the concentration at the moment when the liquor
is at abo
20 degrees. During this concentration I withdraw from the liquor the
are produced in proportion as they are formed.
crystals th
These cr
only a smal!
As regards
's contain almost all the sulphate of soda and the chloride of iron and
rt of the chloride of zinc.
concentrated liquor it contains in solution almost all the chloride
of zinc and on a small part of the chloride of iron and sulphate of soda.
This liquor can be utilized, either by selling it directly as a disinfectant, or by
treating it in order to withdraw therefrom the zinc as hereinafter set forth.
The crystals withdrawn from the liquor during the concentration may replace after
desiccation the paste treated in the calcination of the pasty material.
In the separation of the insoluble ferric oxide by dissolution and washing the
calcined crystals may be treated by water for separating the insoluble oxide of iron
from the soluble sulphate of soda.
After this separation the solution of sulphate of soda freed from iron is treated in a
cooling apparatus which at a temperature of 3 degrees below zero causes the
deposition of the greatest part of the sulphate of soda in the form of crystals.
In the precipitation of the carbonate of zinc the liquor concentrated to about
40 degrees Baumé resulting from the concentration of the mother liquor and
containing almost all the chloride of zinc will be treated for withdrawing therefrom
the zinc by precipitation either in the form of an oxide of zinc or in the form of a
salt of zinc.
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 1
claim is :-
First. The process for recovering the valuable substances contained in the mother
liquor derived from the treatment of copper ores by chlorination which process
consists in the evaporation or concentration of the liquor, either to a pasty consistency,
or only to about 40 degrees Baumé for withdrawing therefrom in the form of crystals
almost all the sulphate of soda and. the ferrous chloride.
Second. The calcination either of the pasty material or of the crystals withdrawn
from the liquor concentrated to about 40 degrees Baumé, for the decomposition of
the chlorinated iron into ferric oxide.
Third. The separation of the oxide of iron from the soluble elements chlorinated
zinc, sulphate and chloride of soda by dissolution and washing.

page_text: Fourth. The treatment either of the dissolving and washing liquor by carbonate of
soda or alkalies for the formation and precipitation of zinc in the state of a carbonate
or an oxide of zinc, or of the liquor concentrated to about 40 degrees Baumé obtained
in the concentration of the mother liquor, for separating therefrom by precipitation
the zinc either in the form of an oxide or in the form of a salt.
Fifth. The treatment of the liquor remaining from the precipitation of the dissolving
and washing liquor by carbonate of soda or alkalies as mentioned in the fourth
claim, or by sulphuric acid for the transformation of the chloride of soda into
sulphate of soda.
Sixth. The treatment of the liquor containing the sulphate of soda in solution
in a cooling apparatus at three degrees below zero for withdrawing therefrom the
sulphate of soda in the state of crystals.
Seventh. For the evaporation or concentration of mother liquor the employment
of a furnace having one or more chambers wherein the liquid is divided by ineans
of shafts W provided with arms or vanes S, or a blowing device having pipes A B,
and traversed by the products of combustion from a gas producer as represented in
the accompanying drawing with the object of considerably accelerating the evapor-
ation, substantially as and for the purpose herein before described.
Dated this 30th day of May 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.