Air Bubbling Valves System In Electrolysis Cells That Decrease The Production Losses Due to Breakage or Physical Damages; And Its Operation Method

Abstract

A system for producing metals includes a reservoir for containing an electrolyte solution and a plurality of conduits disposed within the reservoir. A first gas distributor is operatively coupled with respective first ends of the conduits, and a second gas distributor is operatively coupled with respective second ends of the conduits. Each of the conduits has valves at the respective ends, prior to the first and second gas distributors. A method for producing metals includes bubbling gas into an electrolyte solution through a plurality of conduits and identifying a leak in at least one conduit by closing the respective valves and visually inspecting the bubbling of gas into the electrolyte solution from the remaining plurality of conduits.

Description

BACKGROUND

The electrolytic deposit of metals from solution is normally done in masonry cells coated with electricity insulating materials, acid or alkali-resistant or temperature resistant.

In these cells the fresh electrolyte is fed through one longitudinal end of the cell while the worn electrolyte is discarded by the bottom opposite longitudinal end if the feeding was done through the upper part or vice-versa.

Occasionally the transverse circulation of the electrolyte has been used, i.e. parallel to the faces of the anodes and cathodes with piping with holes located in front of each space inter-anode-cathode, that are placed longitudinally through the bottom at one side of the cell. Through this piping the fresh electrolyte is introduced, while the discharge is done by overflow, or through the other punched piping located at the opposite upper side of the cell.

In order to improve the electricity efficiency, to avoid the deposition of metal on the vertical borders of the cathodes, to improve the quality of the cathode deposit and to decrease the production losses due to the cells maintenance, now removable insulating structures are being used with electrode guides to put position anodes and cathodes as disclosed in the Chilean Patent 45288 (application 1020-2004).

With the same previous objectives, air or other gases are often injected to shake the electrolyte and to make its concentration more uniform which helps to prevent the crystallization of the electrolyte and to decrease the effect of the limit layer. This can be done introducing punched tubes at the bottom of the cell through which air or other gases is injected, which requires the use of fans, feeding ducts and the distribution punched pipes.

The fact of having pipes with gases sunken in the electrolyte make them tend to float making the fixation systems of the pipes to the cell complex.

In recent years, the bubbling of air is done using microporous hoses as a standard of the process since they have the advantage over the punched pipes of allowing a better control of the bubbling characteristics. These microporous hoses like the punched pipes are installed longitudinally on the floor of the cell or next to it, they are normally fed through both ends in order to share the loss of pressure that occurs in the pipes or hoses as the air flows towards the center of the cell.

During normal operation, the failure in the air distribution through the air distributors to their microporous hoses, arises from their physical fatigue, either because of material failure, bumps, accidental fall of anodes or cathodes on the pipes, because of the accidental fall of part of a cathode deposit; the breakage due to the stretching by a hook used to remove solids from inside the cell, that by doing it blindly the operation can cause that when rising the hook it tugs some of the microporous hoses (5) shown in FIG. 1, stretching that also damages the front and the rear distribution heads as shown in FIGS. 2a, 2b, 3a, and 3b.

In order to extend the shell life of the microporous hoses as well as of the punched pipes, attempts have been made to physically protect them with coatings of different types without having effectively solved the issues to date.

In order to control the gas flow sprayed to a distribution system and provide exit openings in the distributing system in order that the fresh electrolyte currents and spraying gas from said exit opens go in a relatively uniform way through the cathodes of the cell, a method as the one described in the Chilean Patent application 200202154 was developed.

Another method to operate a cell that incorporates bubbling gas is described in the Chilean Patent Application 200402120.

In the national search no insulation or protection methods against damages of pipes or microporous hoses of the distribution systems of bubbling gas in electrolytic cells were found.

In the international search, the physical protection for pipes and hoses refer preferably to cover completely those elements with an upper coating like the one disclosed in the Chinese Patent Application CN201593667(U), a lower curved protection to protect the radius of curvature in a horizontal plane, leaving the horizontal diametric plane upwards uncovered as in the Chinese Patent Application CN202040482U, a complete protection of the flexible element (electric conductor or hose) with a corrugated metal coating or a flexible mesh similar to the ones used in the flexible unions used in plumbing to prevent a radial expansion like the one described in the German Patent Application DE102008049497 (A1). Another protection method consists of wrapping with a tape made of elastic material and shock absorbent arranged in a spiral on the surface of the hose as disclosed in the German Patent Application DE 10 2009 053092 A1. Another form of hose protection consists of covering with one or more concentric metal springs arranged in spiral over the hose like the ones used in some connections in automotive hydraulic breaks pipes as disclosed in the Chinese Patent Application CN201925657U. Another way to protect curved hoses is disclosed in the Japanese Patent Application JP2008223940 that covers with one or two moulded circular layers that can be easily separated in fractions.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of the aft supply network, in a quasi isobaric version.

FIG. 2 a shows an isometric view of the front end of the air supply network.

FIG. 2 b shows an isometric view of the front end of the air supply network, including a protective cover above the air distributor.

FIG. 3 a shows an isometric view of the rear end of the aft supply network.

FIG. 3 b shows an isometric view of the rear end of the aft supply network, including a protective cover of the rear air distributor.

FIG. 4 shows a cross section view of an electrolytic cell incorporating inside, a removable insulating structure for anodes and cathodes positioning.

FIG. 5 shows a partial isometric view of the front end of the removable insulating structure for anodes and cathodes positioning, in which the vertical guides for cathodes can be observed.

FIG. 6 shows a perspective view of the removable insulating structure for anodes and cathodes positioning, in which the vertical guides for cathodes are not shown.

FIG. 7 shows a flowchart for the operation of the valve system to keep the bubbling of air or gas running in metal electrolytic production cells

The numbers shown in the figures have the following meaning:

(1) Air inlet.

(2) Front air distributor.

(3) Rear air distributor.

(4) Aft distributor protective cover.

(5-1) Microporous hose in first position.

(5-2) Microporous hose, in second position.

(5-3) Microporous hose, in third position

(5-4) Microporous hose, in fourth position.

(5-5) Microporous hose, in fifth position.

(5-6) Microporous hose, in sixth position.

(5-7) Microporous hose, in seventh position.

(5-8) Microporous hose, in eighth position.

(6) Electrolyte feeding pipe to the cell.

(7) Cathode.

(8) Cathode support bar.

(9) Cathode guide.

(10) Masonry cell.

(11) Plenum collector by add mist suction.

(12) Electrolyte level.

(13) Cathode lower guide.

(14) Microporous hose support.

(15) Support borehole for the microporous hose path.

(16) Lower longitudinal frame, of the removable insulating structure for anodes and cathodes positioning.

(17) Lateral diagonal frame, of the removable insulating structure for anodes and cathodes positioning.

(18) Front horizontal frame, of the removable insulating structure for anodes and cathodes positioning.

(19) Upper longitudinal frame, of the removable insulating structure for anodes and cathodes positioning.

(20) Rear vertical frame, for the removable insulating structure for anodes and cathodes positioning.

(21) Anode lower guide.

(22a) Air stopcock to the air front manifold.

(22a-1) Stopcock of the air front manifold to the pipe and microporpous hose in first position.

(22a-2) Stopcock of the aft front manifold to the pipe and microporpous hose in second position.

(22a-3) Stopcock of the air front manifold to the pipe and microporpous hose in third position.

(22a-4) Stopcock of the air front manifold to the pipe and microporpous hose in fourth position.

(22a-5) Stopcock of the air front manifold to the pipe and microporpous hose in fifth position.

(22a-6) Stopcock of the air front manifold to the pipe and microporpous hose in sixth position.

(22a-7) Stopcock of the air front manifold to the pipe and microporpous hose in seventh position.

(22a-8) Stopcock of the air front manifold to the pipe and microporpous hose in eighth position.

(22p) Aft stopcock to the air rear manifold.

(22p-1) Stopcock of the air rear manifold to the pipe and microporpous hose in first position.

(22p-2) Stopcock of the air rear manifold to the pipe and microporpous hose in second position.

(22p-3) Stopcock of the air rear manifold to the pipe and microporpous hose in third position

(22p-4) Stopcock of the air rear manifold to the pipe and microporpous hose in fourth position

(22p-5) Stopcock of the air rear manifold to the pipe and microporpous hose in fifth position

(22p-6) Stopcock of the air rear manifold to the pipe and microporpous hose in sixth position

(22p-7) Stopcock of the air rear manifold to the pipe and microporpous hose in seventh position

(22p-8) Stopcock of the air rear manifold to the pipe and microporpous hose in eighth position

(23) Anode.

(24) Bubbling electrolysis system in operation

(25) Failure of the air injection line.

(26) Regular bubbling continued.

(27) identification of the line that failed,

(28) Closing of Front and Rear valves of the line that failed

(29) Visual inspection to check if the size and uniformity of the bubbles were restored.

(30) Hoses damaged less than 40%.

(31) Stop of the electrolysis and repair of the damaged hoses.

DETAILED DESCRIPTION

This invention comprises of a system of multiple air stopcocks (22a, 22a-1, 22a-2, 22a-3 . . . to 22a-n, and 22p, 24-1, 22p-2, 22p-3 . . . to 22p-n, wherein “n” equals the number of bubblers used such as microporous punched pipes or microporous hoses, forming ordered pairs of valves), located at the entrance of each distributor (2), (3) and at the front and rear entrance of each punched pipe or microporous hose (5-1, 5-2, 5-3, . . . to 5-n), used to bubble air or gas to a metal production electrolytic cell, in order to put out of service one or the two distributors, or one or more air bubbling hoses that are damaged or destroyed, thereby it is possible to continue to operate the cell with a minimum decrease in the quality of the cathode deposition.

The technical issue solved by this invention consists of avoiding or decreasing the loss of quality/production produced when stopping the operation to repair damages or breakages of the air or gas bubbling distribution hoses; the damages produced by cathodes falls; the partial detachment of the cathode deposit on them; or the manipulation of several tools used to remove solids from the bottom of the cell, as well as to guarantee the operation of the air bubbling system in the same conditions as it was designed, independently of the damage that might be exerted on its aeration networks.

Another approach attempted to solve this same technical issue has consisted of physically protecting the external part of the punched pipes or microporous hoses; anyhow none of the systems used so far to protect the punched pipes or microporous hoses from damages, as described in what is known in the art, has proved to be satisfactory for this application, where the protection should allow the controlled release of bubbling gas in the cell while in operation.

One of the major advantages of this system is that by leaving out of operation the failing or broken porous hose, by closing the valves located at the front and rear air inlet, it is possible to delay the cell operation downtime by two, three and even four times the average failure time of a traditional cell without the valves system of this invention, with a minimum decrease in the quality of the cathode deposition.

The operating procedure for the readjustment of the air or inert gas injection lines, starts with the normal operation of the plant. The air or inert gas is injected through bubbling elements (air or inert gas injection lines), such as microporous hoses or punched pipes, at the start-up. Later, due to various reasons such as cathodes fall, the partial detachment of the cathode deposition on the bubbling lines, or because of the poor handling of various tools used to remove solids from the bottom of the cell, the bubbling lines suffer irreparable damages. Therefore, in order to maintain the quality of the generated cathode deposition, it is necessary to adjust the aeration or gas injection lines, in order to keep a constant and uniform bubbling flow. In order to do this, the identification of the line where the failure occurred is done and consequently the one through which the aft or inert gas leaks. The procedure consists of individually closing the pair of valves of each line and leave the other lines with their valves opened, and make a visual inspection to determine whether the bubbling returns to its normal characteristics regarding the uniformity and size of the bubble. Once the line is identified it is kept with its pair of valves closed and the normal cell electrowinning operation continues. This procedure is repeated each time a line failure is detected or when the bubbling does not exhibit the same characteristics it had at the beginning of the operation.

Some traditional ways to carry out this invention are described below.

One embodiment of this invention, without thereby losing its generality, is shown in FIG. 1, which includes eight microporous hoses (5-1) to (5-8), a front air distributor (2), a rear air distributor (3), and air stopcocks to the front (22a) and rear (22p) entrances of the distributors and stopcocks to the front entrance (22a-1) up to (22a-8) and to the rear entrance (22p-1) up to (22p-8) of each of the hoses (5-1) to (5-8). When a significant air loss occurs in one of the hoses, its identification is done and then the front and rear stopcocks of the damaged branch are closed, which is done without the need of stopping the operation of the cell.

Another embodiment of this invention, is shown in FIGS. 2b and 3b in which a protective cover is included (4) to protect the valves from bumps or accidental fall of heavy elements or objects used in the electrolytic plants.

APPLICATION EXAMPLE

In order to prove the usefulness of this invention a pilot quasi-isobaric feeding net was built such as the one shown in FIG. 1, consisting of a straight grid with 8 microporous hoses.

The quasi-isobaric grid is mounted on the structure shown in FIG. 6 which corresponds to a removable insulating structure to position anodes and cathodes. In this structure each hose is inserted in one of the boreholes (15) as can be seen in FIG. 4. Once beaded the eight microporous hoses of the quasi-isobaric feeding net in the boreholes of the supports (14), they are connected to 8 ducts of rigid plastic material located at the front end and at the rear end of the removable insulating structure to position anodes and cathodes that go up to its upper part as can be seen in FIG. 5.

Each of the rigid plastic material ducts are connected through a ball valve (22a) and (22p) to the air distributors (2) and (3) shown in FIG. 1, located at the front and rear end of the device, subsequently connecting the isobaric feeding to the air general feeding (1) indicated in FIGS. 1, 2a, and 2b.

Once all the quasi-isobaric air feeding net is mounted on the removable insulating structure to ,position anodes and cathodes indicated in FIG. 6 and also partially shown in FIG. 5, all the set is installed inside the masonry electrolytic cell (10).

Once the above is done, the air entrance to the fan of the plant that supplies the bubbling gas was connected, then 61 insoluble anodes and 60 stainless steel cathodes, spaced at 100 mm between cathodes centers, this number is fixed by the distance between the cathodes guides positions (9) of the removable insulating structure to position anodes and cathodes.

Then the cell was filled with electrolyte and was connected to the electric power to deposit metal on the cathodes thereby starting the feeding of electrolyte and bubbling gas.

The operating conditions were set at 2 volts between anodes and cathodes and electrolyte circulation at 30 m/hour and bubbling gas feeding at 15 cubic meters per hour. Then the microporous hoses was damaged (5-2) breaking it, followed by the closing of the stopcocks (22a-2) and (22p-2) in each end of the broken hose. The flow was kept at 15 cubic meters per hour and the operation pressure of the system changed from 1,090 hectopascals to 1,100 hectopascals of absolute pressure and the bubbling process maintained its quality in terms of bubble size, number of them observed and uniformity of the bubbling. There was no loss of gas through the broken hose after the closing of the corresponding valve which permitted to continue with the operation until it finished despite the failure.

The procedure was repeated breaking a second hose, (5-7) and closing the valves (22a-7) and (22p-7), and the feeding of bubbling gas flow was kept the same. This time the operating pressure was changed from the 1,100 hectopascals to 1,110 hectopascals of absolute pressure. Again, the bubbling process maintained its quality in terms of the size of the bubble, the number of bubbles observed and the uniformity of the bubbling. No gas loss was observed through any of the damaged hoses.

After the damages intentionally produced as described above, the operation ran with no interruption until the process was finished and the crop was done in the regular way without inconveniences with regards to the quality of the cathodes obtained.

After multiple experiences performed, suggestion is to stop the operation to repair the aft distribution system when more than 40% of the hoses are damaged, thereby anticipating the moment when the quality of the bubbling decreases and starts to affect the process.

While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.

Claims

1-3. (canceled)

4. A system for producing metals, comprising: a reservoir for containing an electrolyte solution;a plurality of conduits disposed within the reservoir, each conduit having a first end and an oppositely disposed second end, and having apertures operative for bubbling gas into the electrolyte solution;a first gas distributor operatively coupled with the respective first ends of the plurality of conduits for fluid communication therewith; anda second gas distributor operatively coupled with the respective second ends of the plurality of conduits for fluid communication therewith;at least one of the conduits having a first valve at the first end and prior to the first gas distributor, and having a second valve at the second end and prior to the second gas distributor.

5. The system of claim 4, further comprising: a first distributor valve proximate an inlet to the first gas distributor; anda second distributor valve proximate an inlet to the second gas distributor.

6. The system of claim 4, further comprising: a protective cover surrounding at least a portion of at least one of the first gas distributor or the second gas distributor.

7. A method for producing metals, the method comprising: bubbling gas into an electrolyte solution through a plurality of conduits disposed in the electrolyte solution, each conduit having a first end and an oppositely disposed second end, and having a first valve proximate the first end and a second valve proximate the second end; andidentifying a leak in at least one conduit by closing the respective first and second valves of the at least one conduit and visually inspecting the bubbling of gas into the electrolyte solution from the remaining plurality of conduits.

8. The method of claim 7, further comprising: closing the first and second valves of the conduit; andafter closing the first and second valves, continuing bubbling gas through the remaining plurality of conduits.

9. The method of claim 8, further comprising: identifying a leak in at least one additional conduit by closing the first and second valves of the at least one additional conduit and visually inspecting bubbling of gas through the electrolyte solution from the remaining plurality of conduits.

10. The method of claim 9, further comprising: closing the first and second valves of the at least one additional conduit; andafter closing the first and second valves, continuing bubbling gas through the remaining plurality of conduits.

11. The method of claim 8, further comprising: stopping the processing of metals when the number of conduits that have been identified as having leaks is equal to or greater than 40 percent of the total number of conduits.