AU2007201708A1

AU2007201708A1 - Modular system for improving electro-metallurgical processes

Info

Publication number: AU2007201708A1
Application number: AU2007201708A
Authority: AU
Inventors: Andres Cardoen Aylwin; Manuel Umana Casanova; Pedro Aylwin GOMEZ
Original assignee: New Tech Copper SA
Current assignee: New Tech Copper SA
Priority date: 2006-05-30
Filing date: 2007-04-17
Publication date: 2007-12-20
Anticipated expiration: 2027-04-17
Also published as: ZA200704426B; PE20071262A1; CA2586149C; US20070284243A1; AU2007201708B2; CA2586149A1

Description

AUSTRALIA

Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention title: MODULAR SYSTEM FOR IMPROVING ELECTROMETALLURGICAL

PROCESSES

The following statement is a full description of this invention, including the best method of performing it known to us: MODULAR SYSTEM FOR IMPROVING ELECTROMETALLURGICAL PROCESSES SField of the Invention The present invention relates to improvements to electrometallurgical processes, 5 and more particularly to a modular system for improving electrometallurgical processes.

00 Background of the Invention In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date: part of common general knowledge; or (ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.

The industrial obtainment of high purity metals such as copper, nickel, zinc and others is carried out mostly by electrolytic deposits from acid or alkaline water solutions of the respective metals. Whether the metal is obtained from its solutions using insoluble anodes or by dissolving anodes of the metal itself, stainless steel cathodes, also known as permanent cathodes, are vastly used through out these industries.

Although the use of permanent cathodes has solved some processing issues; because the metal is also deposited on their vertical and lower horizontal edges the dislodging of the metal deposited presents severe difficulties. Moreover, since this step is done mechanically by introducing knives between the metal deposited and the stainless steel plate, irregularities on the edges and scratches and deformations on the faces of the cathodes occur. All this means that the stainless steel cathodes must be straightened, repolished and on occasion replaced with the resulting associated costs.

To avoid the electro-deposition of the metal on the edges of the cathodes, some have resorted to covering them with plastic strips to keep them from having contact with the electrolyte. Although the strips are pressure locked onto the sides of the cathodes, the fact that the electrolysis is carried out at temperatures of about 50' Celsius causes the strips to expand and deform. These deformations result in an imperfect seal of the borders of the cathodes that allow large nodules of metal to be electro-deposited on the exposed zones. These nodules add another degree of difficulty to the removal of the plastic strips as well as to the metal deposited. When this occur the metal nodules have agbm AO108072194v1 305807871 to be hammered off to be removed. During this operation the lower ends of the strips are Sdestroyed, making their replacement necessary with the resulting associated costs.

Attempts have also been made to cover the sides of the cathodes that are submerged in electrolyte with a half-frame, shaped like a letter U, of the same metal that is being obtained, so as to form a screen that keeps the deposits from forming on the 00 0 borders. Although it is true that this screen reduces the amount deposited, it does not _solve the entire problem.

In an attempt to resolve this weakness, an effort was made to connect the halfframe to an external source of radio frequency, which would solve the problem.

r' 10 Nevertheless, the fact that the half-frame is made of metal and that it is connected to the same potential of the cathode, causes the metal to deposit also on the outside of the halfframe, increasing its thickness, and forcing its reconditioning or replacement after a few production cycles.

In addition to the problems mentioned, because the anodes and cathodes are suspended freely within the cell, when the anodes and cathodes oscillate occasional shortcircuits are produced that diminish the current efficiency of the operation and force the re-processing of the damaged products and the repairing or replacement of the anodes and cathodes.

All these problems increase production costs and lower the quality of the cathodes produced having detrimental business consequences.

Recently, a holding structure of an insulating material was designed, to which energizable slots were attached. These slots serve as vertical guides for the sides of the cathodes so they have been named "cathode guides". These slots can be energized with a DC current and a high frequency voltage potential to control the cathode peripheral deposit and eliminate the use of plastic strips to solve this problem.

Another problem associated with the operation in the electrometallurgical processes is the formation of acid fog that cause health problems among the workers and damages to the structures of buildings, equipment and instruments. Efforts have been made to try and solve this problem by either inhibiting its formation by the introduction of radio frequencies or preventing its propagation outside the cell by the application of air-curtains to condense the vapors present in the fog and return the condensates to the electrolyte, the use of extraction hoods, surfactants to reduce the surface tension of the solution and minimize electrolyte pulling, plastic spheres to reduce the electrolyte Spulling.

The production of pure metals by electrowinning and electro-refining is executed by the electrodepositing of the metal on a stainless steel sheet (cathode).

00 5 Several problems are present in these processes, as they are executed at present.

One of these problems is that the metals deposit on both faces of the stainless steel cathode, as well as on its edges. The deposit on the edges constitutes a problem for which a satisfactory simple solution has yet to be found. The principal difficulty arises Swhen the metal deposited has to be removed, because irregular edges, creases and C 10 damages occur on the surface of the cathode when the sides are broken to remove the deposit from both faces. These imply a need for reprocessing, a lowering in the price of the product and the reparation or replacement of the stainless steel cathodes.

Another problem refers to the initial charging of the cathodes after a harvest, which at present requires that the electrolyte be emptied out of the cell with the resulting associated cost and loss of production.

Another problem arises from the formation of acid fogs that produce problems related to the workers' health, as well as the corrosion of equipment, instruments and structures.

In an attempt to lessen these problems, in the case of the deposit on the edges, the placing of plastic stripping on the borders of the cathodes and the placing of metal semi-frames joined to the cathode to shield it have been described. But these measures have not resolved the problem. Although the use of energizable cathode guide profiles with application of high frequency unidirectional current resolves the problem of the deposit on the edges, it implies the use of a complex system and the consumption of power.

The formation of acid fog has been tackled with the injection of curtains of air and also with the use of high frequencies, with different degrees of success. To date, nevertheless, the loading of new cathodes in the cell is carried out by emptying all the electrolyte.

Summary of the Invention The modular system for improving electrometalurgical systems of this invention, constituted by a structural nucleus compatible with the use of additional independent Smodules, permits the solving of one or more of the problems listed above, attaching Sspecific modules to resolve each one of said problems. Thus, for example, the use of vertical or horizontal modules to distance anodes and cathodes from each other permits the solving of the problem of the deposits on the borders of the cathodes, without having to recur to the application of high frequency currents, simplifying the solution of the 00 problem and at the same time allowing the electrowinning process to work at higher current densities, without the generation of short circuits, while improving de cathode deposition quality as well as its current efficiency.

The present invention accordingly provides in one embodiment a modular system S 10 for improving electrometallurgical processes, to control perimetric cathodic deposition, (-i compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and transversal circulation of the electrolyte, characterized in that a nucleus formed by upper and lower rectangular frames, linked by corner and/or central pillars, optionally with diagonal lateral and frontal reinforcements, in whose longitudinal (11) and lower left hand beams a set of cathode guides are attached whose function is to keep the positive ion from reaching the border or edge of the cathode, and that it is deposited instead on the cathode face in front of the opening of the cathode guides whose shape is omega-type or U or V type, to insert a bare cathode or one with plastic stripping on the periphery of the cathode, optionally with its corresponding cathode aligners at a distance slightly greater than that of the cathodes that face each other, and a set of anode guides optionally with their corresponding anode aligners and/or an anode spacer module such as that of Figure 4, optionally with two or more sets of cathode type support bars like those in Figure 5, optionally with four or more sets of bracket type anode supports like those in Figure 6 and optionally with sets of four head supports, like that of Figure 7.

The cathode guide profiles that face each other are typically joined at their lower ends by means of another profile.

The cathode guides will typically be mounted at an angle with regard to the vertical defined by the borders of the cathode, slightly increasing its distance at the upper end.

The modular system according to the invention will typically contain an acid fog abatement module.

F. The modular system according to the invention may contain an electrolyte transversal Scirculation module.

The present invention provides in another embodiment the use of a modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting 00 on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, Scharacterized in that it can be used in the production of metals, in the treatment of cI liquid industrial waste and in electroplating.

CI 10 Description of the Drawings Figure la is an isometric view of a sub-assembly of two cathode guide profiles.

Figure 1 shows an enlarged isometric view of the upper part of a sub-assembly of two cathode guide profiles.

Figure 2a shows an isometric view of an anode guide profile.

Figure 2 shows an enlarged isometric view of the upper part of an anode guide profile.

Figure 3 shows an isometric view of the nucleus of the modular system for improving electrometallurgical processes according to the invention.

Figure 4 shows an isometric view of a horizontal spacer.

Figure 5 shows an isometric view of the cathode-type nucleus holder.

Figure 6 shows an isometric view of the anode bracket-type nucleus holder.

Figure 7 shows an isometric view of the head-type nucleus holder.

Figure 8 shows an isometric view of the nucleus positioned inside the cell, during the anode and cathode loading process.

Figure 9 shows an isometric view of the nucleus, with the cathode-type nucleus holders, anode bracket-type nucleus holders and head-type nucleus holders installed in position.

The numbers that indicate the details in the different Figures, have the following meaning: 1. Cathode aligner 2. Cathode guide (in versions to insert a bare cathode or one with plastic stripping).

3. Shock absorber.

4. Anode aligner.

00 5 5. Anode guide.

6. Left longitudinal holding beam of the upper frame of the nucleus.

S7. Rear transversal holder of the upper frame of the nucleus.

8. Right rear corner pillar that joins the upper and lower frames of the nucleus.

9. Cathode guide.

10. Resting component of the nucleus on the floor of the electrolytic cell.

11. Right longitudinal lower holding beam of the nucleus lower frame.

12. Right central pillar that joins the nucleus upper and lower frames.

13. Right diagonal of the nucleus frontal head.

14. Right front corner pillar that joins the nucleus upper and lower frames.

15. Right frontal beam of the nucleus head of the lower frame.

16. Left diagonal of the nucleus frontal head.

17. Intermediate frontal reinforcement beam of the nucleus frontal head.

18. Upper frontal beam of the nucleus frontal head.

19. Right longitudinal holding beam of the nucleus upper frame.

20. Anode housing.

21. Cathode housing.

22. Diagonal lateral stiffener.

23. Window for crane coupling.

24. Coupling angle to the longitudinal holding beam of the nucleus upper frame.

25. Bar of the nucleus holder, cathode type.

26. Anode-type bracket of the nucleus holder.

27. Cube for bolting to the longitudinal support beam of the nucleus upper frame.

28. Support to the upper head of the electrolytic cell masonry.

29. Tip that is fastened to the nucleus.

Cathode.

S31. Anode.

Description of the Modular System for Improving Electrometallurgical Processes The modular system for improving electrometallurgical processes is structured as 00 5 of a Fundamental Module, known as a nucleus, represented in Figure 3, to which other O Modules or elements can be coupled or uncoupled to solve electrometallurgical process problems such as those described previously in the chapter "Description of what is known C about the subject".

In one of the preferred executions, the nucleus of Figure 3 is made up of an upper frame formed by the left and right.(19) longitudinal holding beams and by the front or frontal (18) and rear transversal supports, a lower frame formed by the lower right longitudinal holding beams (11) and another equivalent one on the left side, and the lower beams of the frontal heads (15) and their equivalent in the rear head. Both Frames are joined by means of right hand corner pillars and (14) and their equivalent on the left side, one or more Intermediate Pillars such as that designated with the number (12) and one or more diagonals on the right side like the one designated with the number (22) and its equivalent on the left side. In both heads there are diagonals like those designated as (13) and (16) in the frontal head and other equivalent ones in the rear head.

Optionally and depending on the dimensions of the nucleus, reinforcement Beams can be incorporated like the one designated with number both in the frontal and in the rear head. Optionally, in the lower longitudinal beams (11) and their opposite number on the left side, there are elements for resting on the floor of the cell, such as that designated with the number Depending on the problem that needs to be solved, independent modules with specific purposes can be attached to work in conjunction with the nucleus, which is why it has been designed to be compatible with the following modules: Compatible with Module that eliminates borders or plastic strips.

Compatible with Module for installation in a wet or dry cell.

Compatible with hanging installation or installation resting on the bottom of the cell.

Compatible with acid fog abatement module.

Compatible with module for transversal circulation of electrolyte, SPlastic stripping eliminator module.

In its preferred execution, the plastic stripping eliminator module is made up of a set of cathode guides and optionally a set of anode guides and/or a Spacer Module 00 5 like the one shown in Figure 4. Both the cathode guides as well as the anode guides can be installed, optionally, with their corresponding cathode aligners and anode aligners which are fixed in a vertical position on both interior sides of the nucleus.

The transversal profile of the cathode guide can be shaped like an omega, or a U and/or V, its length being greater than the length of the cathode immersed in the electrolyte, the width of the channel of the omega or of the U and/or of the V profile must be slightly greater than the thickness of the cathode in use. The cathode guides must be installed in such a way that the lower corners of the cathode, once the cathode is positioned in the cell, they are totally covered by the cathode guide. Optionally, the cathode guide can be reinforced with a shock absorber The transversal profile of the anode guide corresponds to a channel whose distance between opposing faces must be slightly greater than the thickness of the anode that will be employed. The aligners have the shape of a truncated cone or inverted truncated pyramid, open towards the center of the cell, and their function is to act as a funnel to facilitate the introduction of the cathodes and anodes respectively into the cell. Depending on the application, the cathode guides may be used only with the anode guides with or without aligners or the cathode guides only with a horizontal spacer module like the one in Figure 4, or the cathode guides together with the anode guides and the horizontal spacer module.

Module for installation in a wet or in a dry cell. The installation in a wet or in a dry cell can be executed by attaching elements to the nucleus that make it easier to lift and transfer it with the help of the traveling crane of the electrowinning plant. These elements can be located in positions occupied by cathodes, by anodes or at the ends of the nucleus.

The version known as cathode-type nucleus holder represented in Figure consists of a bar (25) with two windows for the crane hooks(23) and two coupling angles to be attached to the longitudinal support beam of the upper frame of the nucleus (24).

Two or more of these cathode-type nucleus holders attached in positions normally occupied by cathodes are needed. The version known as anode-type bracket of the nucleus holder, represented in Figure 6, consists of a holder (26) joined to a cube to be attached by means of a bolt or other system, in two or more anode positions, in each one of the longitudinal support beams of the upper frame of the nucleus. The version Sknown as head-type nucleus holder, represented in Figure 7, consists of one end that rests on the electrolytic cell upper head masonry (28) and one end that is attached to the _nucleus These holding systems can be used independently one at a time or in any combination thereof.

00 0 Likewise, they can remain installed permanently or be installed for their use and removed later. By using the plant's traveling crane, these holders make it possible to lift, Sintroduce and/or remove the nucleus from the cell with all the cathodes and anodes in position, whether the cell is empty or full of electrolyte.

C 10 Module for a hanging installation or one resting on the bottom of the cell.

Depending on the type of operation that one wishes to carry out, it may or may not be convenient to rest the nucleus on the bottom of the cell. When, for any reason, one wishes to avoid the resting on the bottom of the cell, the Head Assembly Support Module, consisting of four supports like the one shown in Figure 7 may be installed.

These supports are installed at the ends of the longitudinal support beams of the upper frame of the nucleus and as shown in Figure 9, and their projecting head support ends of the masonry electrolytic cell (28) are located directly over the heads of the cell itself, preventing the lower frame of the nucleus from resting on the bottom of the cell.

Acid fog abatement modules.

As mentioned previously, there are at least two systems patented in Chile to control the acid fog. The modular system for improving electrometallurgical processes of this Invention has been designed to make it compatible with the utilization of either of them.

Electrolyte Transversal Circulation Module.

A module is being developed to facilitate the transversal circulation of the electrolyte.

The modular system for improving electrometallurgical processes of this Invention has been designed to make it compatible with such module.

Example of Application In order to experimentally verify the results of the application of the modular system for improving electrometallurgical processes, and without this meaning a limiting of the System's applicability, a pilot electrolytic cell built with fiberglass reinforced plastic, measuring 40 cm wide by 55 cm long and 35 cm deep was used to simulate an Industrial electrowinning plant to obtain copper was made at a laboratory for which a pilot Selectrolytic cell was used, built of plastic reinforced with fiberglass, measuring 40 cm wide by 55 cm long and 35 cm deep.

The nucleus of the modular system for improving electrometallurgical processes, similar to the one represented in Figure 3, was introduced into this cell. The general 00 dimensions of the nucleus that was introduced into the electrolytic cell are 35 cm wide by 50 cm long and 35 cm high.

In the nucleus used, a module of five cathode guides was coupled to each side Son the left and right (19) longitudinal support beams and on the lower right CI 10 longitudinal support beam (11) and its lower equivalent on the left side. All this with its corresponding cathode aligners Next, a Horizontal Spacer, similar to the one shown in Figure 4, was coupled at the bottom of the cell, with six pairs of anode housing and five pairs of cathode housing The distance between anodes as well as that between cathodes was fixed at 100 mm, the same one used in the simulated Industrial Plant.

Then the five stainless steel cathodes measuring 20 cm wide by 24 cm high by 2 mm thick, mounted on a copper cathodic bar having a diameter of 19 mm and a length of cm, were introduced one by one; then six lead cathodes measuring 14.3 cm wide by 23.5 cm high by 2 mm thick, mounted on a copper anodic bar having the same dimensions as the cathodic bar, were introduced.

Once the cathodes and anodes had been loaded, the cell was filled with copper sulfate electrolyte, having a composition equivalent to that of the simulated Industrial Plant, and the deposit was started at a potential of 2.6 Volts between anode and cathode, employing a current density of 300 Amperes per square meter.

At the end of the operating cycle, the following was observed: Both the chemical as well as the physical quality of the cathode improves. With regard to the chemical quality, a smaller content of Lead, Sulfur and Iron is reflected. On the other hand, the occlusion of copper sulfate on the borders of the deposit is eliminated because the modular system for improving electrometallurgical processes does not use plastic stripping. With regard to the physical quality, by ensuring the parallelism between anodes and cathodes, the short-circuits are eliminated, the grain of the deposit is homogenized and refined, no copper ribbons were observed in any of edges of the copper cathode and a perfectly linear upper border of the cathodic deposit was obtained.

Current efficiency increases. How to take advantage of this benefit depends on the Smetal availability in the electrolyte. That is, the metal production can be increased, the electric power consumption can be reduced, or the harvesting cycle can be shortened.

Improves the increase of current density. This benefit is the direct result of confining the cathodes and anodes inside the modular system for improving 00 0 electrometallurgical Processes, that allows, according to the metal content in the Selectrolyte and without an additional investment, either increase the plant capacity, shorten the harvest cycle or reduce the number of cathodes per cell.

SIt provides an operational path for breaking the paradigm of distance between C 10 cathode and anode. This benefit is the direct result of the confinement of cathodes and anodes within the modular system for improving electrometallurgical Processes that permits, according to the availability of copper and without an additional investment, either to increase the plant capacity by increasing the number of cathodes per cell, to shorten the harvest cycle, or reduce the number of cells.

Equitable distribution of the current through the cathodes. This benefit is translated into a lower variability of the current efficiency, of the weight of the cathodes, and of the chemical and physical quality of the cathodes.

Operational Improvements.

The operational improvements include multiple benefits that arise from the absence of jacketed cathodes, absence of short-circuits and the ease with which the cathodes deposited can be loosened from the stainless cathode substrates with the modular system for improving electrometallurgical processes. The most important of these are: greater availability of equipment, reduction of human resources and reduction of raw materials costs. First, the factors that affect the greater availability of equipment are: 100% detaching in peeling machine, reduction of stripping frequency, increased useful life of the cathode, the anode and the cell, and increased availability of the traveling crane.

Second, the reduction of the Human Resources corresponds to the reduced supervision of short-circuits, manual detachment of plates and rectification of shortcircuited cathodes.

Finally, the cost reduction associated to the product intake used in the EW process relates to the elimination of plastic borders, the elimination of cathode/anode spacers and the consumption reduction of chemical reagents.

12 I i The word 'comprising' and forms of the word 'comprising' as used in this Sdescription and in the claims do not limit the invention claimed to exclude any variants or additions. Modifications and improvements to the invention will be readily apparent to Sthose skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

00 t(- 1^q 0-- 0~

Claims

1. A modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and transversal circulation of 00 the electrolyte, characterized in that a nucleus formed by upper and lower rectangular frames, linked by corner and/or central pillars, optionally with Sdiagonal lateral and frontal reinforcements, in whose longitudinal (11) and lower left hand beams a set of cathode guides are attached whose function S 10 is to keep the positive ion from reaching the border or edge of the cathode, and that it is deposited instead on the cathode face in front of the opening of the cathode guides whose shape is omega-type or U or V type, to insert a bare cathode or one with plastic stripping on the periphery of the cathode, optionally with its corresponding cathode aligners at a distance slightly greater than that of the cathodes that face each other, and a set of anode guides optionally with their corresponding anode aligners and/or an anode spacer module such as that of Figure 4, optionally with two or more sets of cathode type support bars like those in Figure 5, optionally with four or more sets of bracket type anode supports like those in Figure 6 and optionally with sets of four head supports, like that of Figure 7.

2. A modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, characterized in that the cathode guide profiles that face each other, are joined at their lower ends by means of another profile.

3. A modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, characterized in that its cathode guides are mounted at an angle with regard to the vertical defined by the borders of the cathode, slightly increasing its distance at the upper end.

4. A modular system for improving electrometallurgical processes, to control Sperimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, characterized in that it can 00 contain an acid fog abatement module.

5. A modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a wet or in a dry cell, resting on the bottom of the cell or hanging in it and compatible with the S 10 modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, characterized in that it can contain an electrolyte transversal circulation module.

6. Use of a modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and the transversal circulation of the electrolyte, according to claim 1, characterized in that it can be used in the production of metals, in the treatment of liquid industrial waste and in electroplating.

7. A modular system for improving electrometallurgical processes, to control perimetric cathodic deposition, compatible with its installation in a cell with or without electrolyte, resting on the bottom of the cell or hanging in it and compatible with the modules for acid fog abatement and transversal circulation of the electrolyte, characterized in that a nucleus formed by upper and lower rectangular frames, linked by corner and/or central pillars is deposited instead on the cathode face in front of the opening of the cathode guides, whose shape is omega-type or U- or V-type, to insert a bare cathode or one with plastic stripping on the periphery of the cathode.

8. A modular system for improving electrometallurgical processes, substantially as hereinbefore described and with reference to any one of the accompanying drawings.

9. Use of a modular system for improving electrometallurgical processes, substantially as hereinbefore described and with reference to any one of the accompanying drawings.