U.S. patent application number 13/983386 was filed with the patent office on 2013-12-05 for method and device for zinc electrowinning from sulfate solutions.
This patent application is currently assigned to KCM '2000' AD. The applicant listed for this patent is Gencho Bozhilov, Nikola Dobrev, Ivan Enchev. Invention is credited to Gencho Bozhilov, Nikola Dobrev, Ivan Enchev.
Application Number | 20130319877 13/983386 |
Document ID | / |
Family ID | 45922618 |
Filed Date | 2013-12-05 |
United States Patent
Application |
20130319877 |
Kind Code |
A1 |
Enchev; Ivan ; et
al. |
December 5, 2013 |
METHOD AND DEVICE FOR ZINC ELECTROWINNING FROM SULFATE
SOLUTIONS
Abstract
The invention relates to a method and a device for
electrowinning of zinc from sulfate solutions. The electrolyzer for
zinc extraction according to the invention includes a bath-reactor
which is equipped with power supply buses, a pipeline of two pipes
for supplying the electrolyte, cathodes, anodes, plastic strips
along the height of the anodes, an overflow for electrolyte
discharge by gravity. The cathodes have an area of 3.5-10 m.sup.2.
The height of the electrolyzer is at least two times greater than
its width, and the length of the electrolyzer depends on the number
of the electrodes. The bottom of the electrolyzer is divided by a
groove along the length of the bath.
Inventors: |
Enchev; Ivan; (Plovdiv,
BG) ; Dobrev; Nikola; (Plovdiv, BG) ;
Bozhilov; Gencho; (Plovdiv, BG) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Enchev; Ivan
Dobrev; Nikola
Bozhilov; Gencho |
Plovdiv
Plovdiv
Plovdiv |
|
BG
BG
BG |
|
|
Assignee: |
KCM '2000' AD
Plovdiv
BG
|
Family ID: |
45922618 |
Appl. No.: |
13/983386 |
Filed: |
February 2, 2012 |
PCT Filed: |
February 2, 2012 |
PCT NO: |
PCT/BG2012/000004 |
371 Date: |
August 2, 2013 |
Current U.S.
Class: |
205/602 ;
204/269; 204/275.1 |
Current CPC
Class: |
C25C 1/16 20130101; C25C
7/00 20130101; C25C 7/02 20130101 |
Class at
Publication: |
205/602 ;
204/275.1; 204/269 |
International
Class: |
C25C 7/00 20060101
C25C007/00; C25C 1/16 20060101 C25C001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2011 |
BG |
110844 |
Claims
1. An electrolyzer for zinc electrowinning, characterized in that
it includes a bath-reactor (5), equipped with power supplying buses
(6), a pipeline of two pipes (1) for feeding the electrolyte,
cathodes (3), anodes (4), plastic strips (8) along the height of
the anodes (4), an overflow (2) for electrolyte exit by gravity,
where the cathodes (3) have an area of 3.5-10 m.sup.2 and the
height of the electrolyzer is at least two times greater than its
width. The length of the electrolyzer depends on the number of the
electrodes, and the bottom of the electrolyzer is divided by a
groove (11) along the length of the bath (5).
2. An electrolyzer according to claim 1, characterized in that the
anodes (4) are made of pure lead, alloyed with 0.3 to 1.0% Ag.
3. An electrolyzer according to claim 1, characterized in that the
height of each anode (4) is divided into two equal parts and their
total effective area is greater than that of the cathode (3), and
the thickness of the anode (4) is 12-18 mm.
4. An electrolyzer according claim 1, characterized in that power
feeding buses (6) are made of copper and there is a copper bar (7)
fixed on them.
5. An electrolyzer according claim 1, characterized in that the
plastic strips (8) are installed so as to cover the edges of anode
(4) to at least 80% of the height and in the middle and the lower
part the anodes are fixed by a plastic disc washer (10) between
anode (4) and cathode (3).
6. An electrolyzer for zinc electrowinning, characterized in that
it consists of two connected electrolyzers according to claim 1,
where between the two baths is provided a siphon-overflow (9) for
the solution, leaving the first bath by gravity and entering the
second bath from the bottom to the top.
7. A method for zinc electrowinning with a device according to
claim 1, characterized in that it consists of: feeding process
electrolyte solution, containing zinc, sulfuric acid .about.120-200
g/l and additives as an option at the temperatures of 25-32.degree.
C. at the inlet and 36-38.degree. C. at the outlet, and pressure
1.5-2 atm., through a pipeline (1) into the bath-reactor (5) and
electric power by means of the buses (6); electrolysis at the
current density of 250-500 A/m.sup.2, maintaining electrolytic
solution circulation speed of 1.5/3 bath volumes per hour, where
the anode-to-anode distance is .about.80-86 mm and the duration of
the cathode cycle is 72 hours (48-96 hours), and the temperature of
the electrolyte at the exit is 36-38.degree. C.
8. A method according to claim 7, characterized in that the process
electrolytic solution contains 120-200 g/l sulfuric acid.
Description
FIELD OF THE INVENTION
[0001] The invention is related to a method and a device for zinc
electrowinning from sulfate solutions.
BACKGROUND OF THE INVENTION
[0002] Various methods and devices are known for obtaining
electrolytic zinc and 90% of its production is realized by
hydro-electrometallurgy. In the conventional electrolytic baths the
process is carried out with current densities of .about.400/600
A/m.sup.2, cathode surface .about.1.0/1.6 m.sup.2 and manual
stripping of zinc cathodes from the cathode sheets in 24 hours. A
novelty in this direction, the application of which began
approximately 25 years ago, are the so called Jumbo baths and
electrodes of an area of .about.2.60/3.40 m.sup.2, each bath
charged with .about.80/120 cathodes. This technology is now being
used by the modern electrolytic zinc plants and zinc stripping is
done mechanically by various devices in every 48 hours at
.about.3100/3500 kWh/t energy consumption.
[0003] The disadvantage of all known processes and apparatus,
regardless of the relative increase in productivity, is the main
factor of effectiveness in electrowinning of metals, namely
electricity consumption. The latter represents .about.70% of the
total processing costs for zinc extraction, along with those for
electrode management, electrolyte cooling, labor costs,
consumables, etc.
TECHNICAL DESCRIPTION OF THE INVENTION
[0004] The essence of the method and the device according to the
invention or the new technology and equipment for zinc
electrowinning is the creation of a new generation of electrolyzers
regarded as a kind of rectors. This is dictated by the process
which is a complex function of electric potentials, oxi-reduction
acts and hydro-aerodynamic environment in which the bath (reactor)
is conditionally divided into upper and lower and, respectively,
left and right symmetric zones. This design and, respectively, the
process are consistent with the electrode potentials, productivity,
electrode configuration, fixation and positioning of the cathodes
and anodes, their formation and processing, the electrolyte
circulation system and other factors. Besides, the separated
gases--oxygen on the anodes and hydrogen on the cathodes--create a
peculiar "fluid bed" and contribute to the movement of the
electrolyte between the electrodes from the bottom to the top and
vice versa apart of them. Furthermore, the charging of the fresh
solution at the pressure of .about.1.5/2.0 atm., its leading away
by means of an overflow as a waste solution and the anode fixing
devices have favorable effect on the movement of the solution (FIG.
2, [a] [b]).
[0005] In principle the electrolyzer can be formed longitudinally
by two, connected by an overflow, baths, charged by a common
circulation line, so that the velocity of the circulation doubles
and it is possible to place additional cathodes and anodes (FIG. 5,
[a] [b]).
[0006] The aim of the method and the device according to the
present invention of a new generation of zinc electrowinning is,
while maintaining high productivity, to increase process efficiency
by reducing energy costs by .about.20/30% and other related
processing costs as a whole at comparable investment costs for
construction, machinery, equipment and installation
(engineering).
[0007] This is achieved by the introduction of a new design of an
electrolysis bath and, respectively, electrodes, loaded into it
compared to the existing ones so far.
[0008] What is characteristic here is that, while comparatively
maintaining the accepted in practice width and length of the
electrolyzer, its height is doubled, i.e. the mentioned upper and
lower zones are already formed (FIG. 1). This allows increasing the
effective area of the electrodes--min. 3.5 m.sup.2 and max.
.about.10 M.sup.2 for one cathode; this change is consistent with
the features of the process, its parameters, etc., "dispersion
capacity of electrolyte". In this way the used current density of
up to 500 A/m2 can be reduced to 250/300 A/m2, leading to a
reduction in the electrode potentials, energy consumption,
respectively, without affecting the high performance at periodic
deposition time of 48 to 96 hours. This change in the bath and
electrodes configuration determines the changes in other
parameters, which is indicated in the attached figures.
[0009] FIG. 1 shows the overall appearance of the device, and FIG.
2 [a]--its projections, representing the bath-reactor 5, equipped
with power supply buses 6, pipeline 1 for feeding the electrolyte,
loaded with cathodes 3 and anodes 4, which are necessary for the
process. Electrowinning is realized by feeding the process solution
through pipeline 1 with the pressure of .about.1.5/2 atm. and
electric power--by buses 6. The electrolyte enters the bath through
two pipes 1 by gravity at the upper end and the middle of the bath
(FIG. 2a) and leaves the reactor at the other end by means of an
overflow 2 along its entire width (FIG. 2b). The fed electric
current is distributed between the electrodes--cathodes 3 (FIG. 2)
and anodes 4 (FIG. 2) and the process of electrowinning is carried
out with the current density of .about.250/500 A/m.sup.2. The
electrolyte temperature at the entrance of the bath is
.about.25/30.degree. C. and, respectively, .about.36/38.degree. C.
at the outlet; sulfuric acid content is .about.120 to 200 g/l. The
speed of electrolyte circulation is maintained at .about.1.5/3 bath
volumes per hour and the distance between the electrodes is 80/86
mm.
[0010] The used anodes 4 (FIG. 3a and FIG. 3b) are made of lead,
containing .about.0.5/1.0% Ag (cast of rolled) and are formed by
two symmetrical sheets, copper bar 7 for upholding in the bath and
conducting the current and plastic strips 8 for fixation (linear
speed .about.0.15/0.30 m/min).
[0011] FIG. 4 shows the plastic strip in two projections. The strip
is secured along both ends of the anodes and helps their accurate
positioning in the bath. Besides, the anodes are formed in such a
way that their effective area increases with the height thanks to
their vertically riffled surface (FIG. 3b); the anodes are
.about.12/18 mm thick.
[0012] A version of the offered device, according to the present
invention, is the twin electrolyzer, or two baths connected in a
common system (FIG. 5a and FIG. 5b). In this case the electrolyte
enters the baths by means of two pipes 1 at their upper ends, or
the total number of the pipes is 4 (FIG. 5); power is fed by
separate buses for the two volumes of the twin bath where the spent
solution leaves by gravity the first bath along its entire width at
the top and by means of a siphon-overflow enters the second bath
bottom--up (pos. 9, FIG. 5).
[0013] The bottom of the electrolyzer (FIG. 2a) is divided along
the length of the bath by groove 11 which allows the settling of
the electrode sludge (relative weight .about.5 g/cm.sup.3) and its
periodical removal, while the anode surfaces are cleaned outside
the bath by means of a suitable treatment (including ferrous
sulfate solution) and collecting the sludge (above 60% MnO.sub.2)
to use it as an oxidizer. Anode cleaning is carried out in ferrous
sulfate solution followed by treatment with rotating brushes and
water shower under pressure; anode sheets are corrected only if
necessary by means of an appropriate "pressing".
DESCRIPTION OF THE ENCLOSED FIGURES
[0014] FIG. 1--General view of the device of the present
invention;
[0015] FIG. 2a--The device of the present invention, shown in three
projections;
[0016] FIG. 2b--Electrolyte overflow of the present invention;
[0017] FIGS. 3a and 3b--Lead anode for zinc electrowinning of the
present invention;
[0018] FIG. 4--Plastic (PVC, PPL, etc.) strip-clamp for fixing the
electrodes of the present invention;
[0019] FIG. 5a and 5b--Another version of a twin bath of the
present invention.
EXAMPLES OF PREFERRED EMBODIMENTS
Example 1
[0020] Electrowinning is realized in an electrolyzer of the volume
of .about.30 m.sup.3, height--3.5 m and width--1.6 m, fed with 60
cathodes 3, each one having an area of .about.6 m.sup.2. The
density of the supplied current is .about.300 A/m.sup.2. The
electrolyte enters the bath-reactor 5 through two (diffusion) pipes
1 at the speed of .about.500/700 l/min and exits along its entire
short side through overflow 2. The lead anodes 4 are formed by two
symmetrical parts and their surface is shaped like stepped grooves
with tapered lower part and at least 80% of anode 4 is fixed by
plastic strips, which are supplemented by plastic washers 10 at the
middle and lower end of anode 4. The mixed electrolyte enters the
reactor, containing 70 g/l zinc and 180 g/l sulfuric acid at the
temperature of .about.30.degree. C. (.about.37.degree. C. at the
outlet) with the necessary additives; yield is 90% and energy
consumption--.about.2600 Kwh/t zinc.
[0021] The duration of the cathode cycle is .about.72 h; metal
purity is 99.995% Zn.
Example 2
[0022] The process is carried out in a twin electrolyzer, formed by
two baths with an intermediate wall, connected by a siphon, along
their entire width. The baths are charged with 62 cathodes each,
i.e. .about.124 cathodes with an area of .about.6 m.sup.2 each;
circulation is achieved with 4 pipes--diffusers (two at each inlet)
in their upper parts and in the middle, overflowing between them
top-down at the speed of .about.800/1200 l/min. Anodes
configuration and fixing elements are the same as in Example 1.
Current density is .about.300 A/m.sup.2 and the cycle of zinc
deposition is 72 h. The yield is .about.90%, energy
consumption--.about.2700 Kwh, purity .about.99.995% Zn with the
same electrolyte. Effective sludge removal is done in .about.30
days.
* * * * *