KR100691080B1 - Method and apparatus for electrowinning powder metal from solution - Google Patents

Abstract

A cell 1 is disclosed for electrorefining a metal from a solvent in powder form. The cell 1 comprises a housing 2 having an outlet 3 on one end thereof and an outlet 4 on the opposite end. The cell has a cylindrical anode 6 extending substantially axially through the housing 2 and a cathode 7 which is spaced outwardly away from the housing and surrounds the anode 6. The anode 6 and the cathode 7 form a flow passage 8 with a gap between 5 mm and 25 mm between them. In use, the cell is in a substantially vertical orientation with the inlet 3 at the bottom and the outlet 4 at the top. During the flow of the process solvent through the cell 1, metal powder is deposited on the cathode 7. Periodically the flow process solvent is shut off and the flush solvent is passed through the cell in the opposite direction to remove powder metal from the cathode 7. Also disclosed is a bank of cells in which individual cells are connected in parallel to the main inlet and main outlet, respectively.

Description

Metal refining cell and its banks and how the refining cell works {METHOD AND APPARATUS FOR ELECTROWINNING POWDER METAL FROM SOLUTION}             

The present invention relates to a method and apparatus for electrowinning metal from a metal containing solvent. In particular, the present invention relates to the production of particulate metals, such as powder form, separate from the plated metals.

In particular, the invention relates to, but is not limited to, methods and apparatus for electrorefining copper in powder form from, for example, copper-containing solvents such as low grade copper solvents often found in mines and mineral processing plants. The following describes the present invention with reference to these exemplary applications. However, this may also apply to other metals such as silver, nickel, cobalt and tin.

Applicant has designed an electrorefining cell for electrorefining metals such as copper and tin from aqueous solvents. Such cells are disclosed in International Patent Application No. PCT / AU96 / 00332, entitled “Mineral Recovery Device”. The contents of this patent application are incorporated herein by reference.

The patent application discloses a cell having a tangential inlet at the bottom of the housing and a tangential outlet at the top of the housing. The orientation of the inlet in combination with the cylindrical housing to orient the solvent into the cell at a particular orientation induces a helical flow through the cell. The rod-shaped anode extends axially in the length of the housing coaxial with the cell, and the split sleeve cylindrical cathode is supported towards the wall of the housing and circumferentially surrounds the anode spaced outward therefrom. In use, a potential difference is applied across the flow path between the cathode and the anode to drive the electrorefining metal fabrication process. The helical flow through the cell from the inlet to the outlet causes copper ions to be present in the cathode, making copper an economical solution for low grade solvents. Plate uniformly and continuously.

This process gradually plated a copper tube on the inside of the split sleeve. Copper plating is taken out when the copper plating is about 6 cm to 8 cm (2.4 inches to 3.14 inches) thick. This is accomplished by removing the top cap from the cell and lifting the split sleeve through the top of the cell. This is a labor intensive process and interferes with the other continuous nature of the process.

When a commercial plant using the process actually contains banks of hundreds of cells, the creation of cells in the above-described method is a labor intensive process. Another drawback to the production of copper tubes by the methods described above is that the tubes require specific handling and return procedures. Thus, it would be advantageous if an easier method for producing copper from the electrorefining cell was provided.

In addition, the above-described electrorefining cell does not have an optimum efficiency due to the large gap or distance between the cathode and the anode. As a result, a relatively high voltage can be applied across the cathode and the anode, and the applicable current density becomes relatively low. When the amount of metal produced is directly proportional to the current density across the cathode and anode, it is desirable to have as high a current density per quantity of power input as possible.

Summary of the Invention

According to a first embodiment of the present invention, in a cell for electrorefining a metal in powder form from a solvent,

A housing having an inlet at one end and an outlet at the opposite end;

An anode extending substantially axially through the housing;

A cathode spaced outwardly away from the anode to surround the anode, the cathode forming a flow passage of 5 mm to 25 mm between the anode and the cathode;

A metal electrorefining cell is provided that includes means for applying a potential difference between the anode and the cathode.

Thus, the cell has a substantially narrower gap between the cathode and the anode than the electrorefining plating cell or cylindrical cell for making the copper tube. This helps to increase the current density between the cathode and the anode, especially for low conductive solvents.
Typically, the housing does not have mechanical means in the housing to remove solvent through the housing, and the housing does not have mechanical stripping means for mechanically peeling the plated metal from the cathode after the metal has been deposited. .

More preferably, the gap is 5 mm to 20 mm, more preferably 10 mm to 15 mm, most preferably 12 mm to 13 mm.                 

Typically both anode and cathode are substantially cylindrical. The cathode is formed by a wall of the housing or by a sleeve located adjacent to the wall of the housing. Preferably, the cathode is formed by the wall of the housing which is metal.

Typically, one end of the cell is relatively upper orientation, the opposite end of the cell is relatively lower orientation in use, the inlet is located at or near the lower end, and the outlet is at or near the upper end. do.

Thus, in use, the process solvent containing the metal ions to be electrorefined is moved upwardly through the cell from the inlet to the outlet, and the metal is deposited in powder on the cathode. Periodically, the flush solvent must be pumped in the opposite direction through the cell to remove the deposited powder metal from the cell for production. The process solvent is preferably moved through the cell so that the gas generated by the electrorefining process can be vented through the vent associated with the upper region of the cell. In particular, the flushing solvent is preferably moved downwardly through the cell so that gravity assists the flushing process. Typically, the flush can be assisted by increased pressure of the flush solvent and other factors such as passing bubbles and other means onto the cathode to help break down the metal powder.

Preferably, the inlet directs the solvent substantially axially into the cell.

Preferably, the outlet is oriented such that flush fluid passed into the cell in the opposite direction is axially directed into the cell.                 

In a preferred form, the inlet is formed at the one end of the cell and the outlet is formed at the opposite end of the cell.

The orientation of the inlet and the gap in the flow passage facilitate the flow of the process solvent through the flow passage with turbulence. This is very different from the tangential cells in the prior art cells which induce a spiral plug flow through the cell from the inlet to the outlet. Plug flow is fundamentally different from turbulence.

Similarly, the flush solvent flowing in the opposite direction through the outlet of the cell is advantageously oriented axially into the cell to promote turbulence. This turbulence of the solvent helps to remove metal powder from the cathode.

Preferably, the cell comprises means for guiding the powder cleaning the cathode towards the inlet during the flush cycle through which powder is drained from the cell. The guide means may be formed by an inner surface of the housing which slopes inwardly downwards on the inlet side.

This reduces the tendency of the metal powder to be contained in the square space at the bottom of the cell and helps to drain the metal powder completely out of the cell.

Preferably, the cell further comprises mechanical cleaning means for breaking up all dendritic crystals of the metal that may form in the flow path between the anode and the cathode. Optionally, the mechanical cleaning means may comprise a mechanical cleaner that is physically moved along the flow passage, although other cleaning means may also be used.

Inherently, process flow parameters are set to reduce the tendency for dendrite of metal solids, for example metals, to deposit on the cathode. Accordingly, the Applicant has found that it is very undesirable for metal plating shields such as dendritic crystals to be formed in the flow passages. In order to provide a means for checking and removing barriers to metal, one must provide a clear piece of process requirements for use in a commercial plant.

Preferably, the end of the anode is closed to direct the fluid around the anode and through the annular flow passage. One end has a flow formation with a generally conical configuration for directing the flush solvent flowing through the outlet towards the flow passage. The closed end allows the solvent to flow around the anode and through the flow passage.

The cell also includes a support member mounted at one end of the housing and protruding substantially axially into the housing, the support member including a support for supporting the anode. The support member mechanically supports the anode at a suitable position aligned vertically with the cathode and also electrically connects the anode to the electrical circuit.

In a particularly preferred form, the housing comprises a cylindrical body of stainless steel and an end cap of non-conductive material, each of which forms a chamber axially outward of the cathode and the anode. One of the end chambers forms the inclined inner surface described above to guide the powder metal through the inlet.

This method allows the cylindrical body forming the cathode to be electrically separated from the support member and the electrical connection to the anode passed through one of the end caps.
The anode and flow former ensure that the solvent flows around the anode and through the flow passage. The support member supports the anode in a suitable position vertically aligned with the cathode and electrically connects the anode to the electrical circuit.

In a particularly preferred form of cell, the diameter of the cathode is 7.5 inches to 8.5 inches, preferably about 8 inches, and the diameter of the anode is 6.5 inches to 7.5 inches, preferably about 7 inches, and the gap between the anode and the cathode is 0.5 inches to 1.5 inches, preferably about 1 inch. Also in the most preferred form, the housing extends substantially vertically, the inlet is formed in the bottom end of the cell and the outlet is formed in the top end of the cell.

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According to another embodiment of the present invention, in a bank of cells,

A plurality of cells as described in the first embodiment arranged in parallel,

A main inlet directly connected to each inlet of a cell in a bank for orienting parallel process solvent through the cell;

A main outlet directly connected to each outlet of said cell for directing process solvent away from said cell,

Means for interrupting the flow of process solvent through the bank of cells when necessary, and then passing through the main outlet and passing flush solvent in opposite directions through each of the cells of the bank and through the main inlet. A bank of is provided.

Thus, in use, the process solvent is passed in parallel through each of the cells of the bank, and then the flush solvent is periodically or intermittently passed in parallel in the opposite direction through the cell to flush the powder metal out of the cell.

Advantageously, said flow reversal means comprises process solvent inlet valve means for opening and blocking flow of process solvent into said main inlet, and process for opening and blocking flow of process solvent exiting said main outlet in a downstream direction; Solvent outlet valve means; Flush solvent inlet valve means for opening and blocking flow of flush solvent into the main outlet, and flush solvent outlet valve means for opening and blocking flow of flush solvent exiting the main inlet.

Thus, control of each process and flush solvent flow through the bank of cells can be achieved by a main inlet and main outlet and a set of valves associated with each of the process and flush solvent. This makes for a very simple recirculation and valve arrangement for banks with multiple cells. This is simpler than having a separate valve arrangement for each cell.

The bank may further comprise, for example, control means for controlling the valve such that only flush solvent or process solvent flows through the bank at one time. Many different control means can be used, but PLC controllers are particularly useful.

Control of the valve means can be accomplished in a variety of ways, including by manual control. The PLC controller is a tested instrument of off-the-shelf instrument that can be used to reliably control the process.

Typically, the bank further includes means for venting gas generated by the electrorefining process from the cells in the bank. Typically the vent means comprise a vent operatively coupled to the main outlet.

Vents are important for removing gases generated by electrorefining processes in commercial plants. By providing a main outlet operatively coupled to each outlet of the cell, a single vent can be used to vent all cells in the bank. This is simpler and cheaper than having a vent for each cell.

Preferably, the main inlet is adjacent to each lower end of the cell and the main outlet is adjacent to the upper end of the cell. Inherently, the main inlet and outlet will be positioned to reduce the length of the pipe as needed.

According to another embodiment of the invention, there is provided a method of operating an electrorefining cell for electrorefining a metal from a solvent, the cell having a substantially cylindrical cathode surrounding the anode and the spaced inlet and outlet and the anode and In a method of operating an electrorefining cell, in which a flow passage is formed between the cathodes,

Passing the metal ion containing process solvent through the flow passage from the inlet to the outlet while simultaneously applying a voltage across the cathode and the anode to deposit particulate metal from the solvent on the cathode;

Periodically interrupt the flow of the metal ion-containing process solvent through the cell, pass the flush solvent through the cell in the opposite direction, flush solvent removes the metal powder from the cathode, clean the metal powder from the cell and recover the metal of the plant There is provided a method of operating an electrorefining cell comprising introducing it into the unit.

The method may further comprise recovering the particulate metal from the flush solvent, such as in the metal recovery portion of the metal.

Advantageously, the method further comprises interrupting the flow of the flush solvent when particulate or powder metal is removed from the cell and restoring to normal flow of solvent through the cell to further plate copper.

The method includes flushing the cell after 1 hour to 6 hours of pumping process solvent through the cell, typically 2.5 hours to 4.5 hours after passing process solvent through the cell. Typically, the flush solvent is passed through the cell for 15 to 30 seconds, preferably 20 to 25 seconds.

Preferably, the process solvent is passed through the cell at a flow rate of 1,000 liters / hour to 3,500 liters / hour, preferably 2,000 liters / hour to 3,000 liters / hour, and the flush solvent is 6,000 liters / hour to 10,000 liters / hour, preferably Pumped through the cell at a flow rate of 7,000 liters / hour to 9,000 liters / hour.

Typically, the flush solvent is pumped through the cell at a higher pressure than the process solvent. This higher pressure helps to remove metal powder from the cathode.

In typical cells during normal operation, the metal ion containing process solvent is moved in the cell from the inlet to the outlet, and the flush solvent is moved down the cell from the outlet to the inlet in the opposite direction. In this method, gravity is assisted by the help to remove the powder metal from the cathode and to clean the powder metal from the cell.

The method also includes periodically passing a mechanical cleaner through the flow passage to remove all plating, other solid resinous crystalline phases, etc. that may be plated on the cathode.

The method may also include assisting the removal of powder metal from the cathode by passing bubbles such as bubbles through the flow passage of the cell after the flow of process solvent is interrupted and before the flow of flush solvent begins. have.

According to yet another embodiment of the present invention, there is provided an electrorefining plant comprising a plurality of banks of cells as described above with reference to the second embodiment of the present invention, wherein the banks are operatively coupled together so that Process solvents containing a metal to be passed can be passed through each of the banks in series.

Typically, the flush solvent passes in the opposite direction through the bank of cells.

Typically, flushing solvent is passed all at once through only a single bank of cells. The flush solvent does not pass in series in the opposite direction through all banks.

The plant may comprise at least three banks of cells in series. For all specific applications the exact number of banks will depend on the initial grade of the process solvent, the target grade of the product solvent, as well as the current density in the cell.

Typically, only one bank of cells is shut off to flush the flow of process solvent all at once. In this way the flow of process solvent through the plant needs to be continuous, and only one bank of cells performs manufacturing to flush all at once.

1 is a front sectional view of a cell according to the present invention in a steady state process flow;

2 is a front sectional view of the cell of FIG. 1 in flush flow;

3 is a front view of the bank of the cell of FIG. 1 operatively coupled to each other;

4 is a process flow diagram of multiple banks of the cell of FIG.

The apparatus and method according to the invention can be varied in various forms per se. Hereinafter, some preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The purpose of these figures is to teach those skilled in the art how to practice the invention in practice. However, the specific nature of this description does not replace the principles of the foregoing description.

1 and 2, reference numeral 1 denotes a cell according to the present invention.

In general, the cell 1 comprises a housing 2, which has an inlet 3 at its lower end and an outlet 4 at its upper end. The cell 1 further comprises an anode 6 extending in the axial direction and a cathode 7 radially spaced apart from the anode 6. A flow passage 8 is formed between the anode 6 and the cathode 7 through which the process solvent passes from the inlet 3 to the outlet 4. The cell also includes power and electrical circuitry for applying a potential difference across the cell between the anode 6 and the cathode 7. In use, the cells alternate between the process flow state shown in FIG. 1 and the flush flow state shown in FIG. 2.

The housing 2 is generally elongated circular cylindrical body 10, for example made of stainless steel, and end cap 11, for example made of engineering plastics material, mounted at each end of the cylindrical body 10. , 12). Typically, the end caps 11, 12 are not necessary but are permanently mounted to the body 10. In the embodiment shown, the end of the body is flanged and the end cap is mounted to the body by bolts passing through the flange and the end cap.

In a preferred form, the body 10 has a diameter of 6 inches (152.4 mm) or 8 inches (203.2 mm). An axially extending inlet 3 is formed in the bottom end cap 12 of the housing 2, which orients the process solvent axially into the housing 2. In the embodiment shown, the precise position of the inlet is not essential but the inlet 3 is eccentrically positioned.

Typically, the diameter of the inlet 3 and outlet 4 is 35 mm to 40 mm. This facilitates flow rates from about 1,000 liters / hour to 3,500 liters / hour through the cell during normal process flow conditions and from 6,000 liters / hour to 10,000 liters / hour during flush flow conditions.

The outlet 4 extends axially away from the upper end cap 11 of the housing in a form similar to the inlet 3. However, the outlet 4 is centered as shown. When the powder metal is flushed from the cell, the outlet 4 acts as an inlet for the flush solvent and the inlet 3 acts as an outlet for the flush solvent as described in detail below.

The cathode 7 is formed by the wall of the body 10 made of an electrically conductive material as described above.

Similarly, the anode 6 is cylindrical in size to form a relatively small gap and flow passage 8 between the anode 6 and the cathode 7. Typically, the width of the flow passages is on the order of 10 mm to 15 mm. Thus, the difference in diameter between the cathode and the anode is typically about 1 inch (25.4 mm). In the illustrated embodiment, the diameter of the anode 6 is 7 inches and the diameter of the cathode 7 is 8 inches.

The anode 6 is supported by a support member 15 which protrudes through the lower end cap 12 of the housing 2. The support member 15 is positioned substantially centrally with the inlet 3 eccentric. The member 15 is attached to both the end cap 12 and the anode 6 to support the anode in a suitable vertical position with the cathode.

Of course, the upper and lower ends 18, 19 of the anode 6 are closed to direct the flush solvent around the anode 6 into the flow passage 8. The upper end of the anode 6 includes a conical flow forming portion 20 for orienting the flush solvent entering the housing 2 around the anode 6 and through the flow passage 8.

The end caps 11, 12 space the inlet 3 and the outlet 4 axially away from the ends of the cathode 7 and the anode 6. This forms the chambers 21, 22 adjacent to the inlet 3 and the outlet 4. In the embodiment shown, the chamber 22 has a flow surface 23 that slopes inwardly toward the inlet 3 from the side of the end cap 12. This helps to guide or orient the powder metal towards the inlet 3 when the powder metal is flushed at the cathode 7.

In the process flow state, a process solvent containing metal ions for electrorefining Cu ions is passed upwardly through the cell from the inlet 3 to the outlet 4 as shown in FIG. 1. While the process solvent is passed through the flow passage 8, a voltage is applied across the flow passage from the cathode 7 to the anode 6. This allows the deposited metal, for example in the form of metal particles or metal powder, to be deposited on the cathode 7. After a few hours, when solid copper at least partially occludes the flow passage 8, the flow of process solvent through the cell 1 is blocked.

The cell promotes the deposition of powdered metal on the cathode. Formation of the powder separately from the plated metal is promoted by turbulent flow in the flow passage, reducing the flow rate of the process solvent, thereby reducing the speed of the process solvent on the cathode as compared to the applicant's prior art cells, and The density can be reduced, the current density can be reduced, and relatively low grade solvents can be processed. Certain process parameters will result in the formation of powder metals that depend on the grade of the process solvent.

Lowering the grade of the metal in a solvent more similar to the metal will produce a powder. In addition, lowering the velocity of the fluid through the cell and the current density will produce a powdered metal that is separate from the plated metal. In addition, turbulence through the cell separate from the plug flow also promotes the formation of powder.                 

Thereafter, the flow of the flush solvent takes place in the opposite or downward direction from the outlet 4 to the inlet 3. The flush solvent assisted by gravity moves the powder metal deposited on the cathode 7, which displaces the cathode 7 downwardly toward the inlet 3. The inlet 3 acts as an outlet in the flush flow state.

The tapered walls of the chamber formed by the end cap 12 help to guide the powder metal towards and through the outlet 3. The pressure of the flush solvent is typically higher than the pressure of the process solvent to assist in the flush process.

Typically, the powdered metal from the inlet 3 is transported to a downstream collection or other treatment point by, for example, flush solvent upon gravity drainage.

The flush flow state is typically run for 20-25 seconds, but this particular time is not critical. After the metal is flushed from the cell, the flow of flush solvent is interrupted and the flow of process solvent is recovered.

In Fig. 3, reference numeral 30 denotes a bank of cells collectively. Each of the cells is as described above with reference to FIGS. 1 and 2. Thus, the components of the cells in FIGS. 1 and 2 used the same reference numerals.

Each bank 30 of cells typically comprises 5 to 20 multiple cells 1 connected in parallel. The main inlet 32 is operatively connected to each inlet 3 of the cell 1, and the main outlet 34 is operatively connected to each outlet 4 of the cell 1.

Process solvent inlet conduit 36 is operatively connected to main inlet 32. Similarly, process solvent outlet conduit 38 is also operatively connected to main outlet 34. Process solvent inlet and outlet valves 40, 41 are provided to open and block the flow of process solvent through the main inlet and outlet 32, 34.

Correspondingly, main outlet 34 is connected to flush solvent inlet conduit 42 and main inlet 32 is connected to flush solvent outlet conduit 43. Typically, this is a gravity drain leading to the settling cone. In addition, these conduits are coupled with valves 44 and 45 similar to valves 40 and 41.

The bank 30 also includes gas vent means in the form of a riser 46 that includes a pneumatic valve that protrudes from the upper region of the main outlet 34. This may exhaust the gas generated by the electrorefining process from the process when needed. This also makes it possible to achieve efficiently by having a single vent for the entire bank 30 of cells.

Typically, the valves 40, 41, 44, 45 are pneumatic valves, although other valves may also be used.

Bank 30 also comprises control means in the form of a PLC controller for opening and closing the valve to change the bank between the process flow state and the flush flow state. Each process flow cycle ends in one to three hours, for example two hours, and each flush flow cycle ends in 20 to 25 seconds.

In use, the process solvent passes through the valve 40 and passes through the conduit 36 into the main inlet 32. This process solvent then flows in parallel through each of the cells 1. While passing through the cell, the metal is electrorefined from the process solvent as described above with reference to FIGS. 1 and 2. The process solvent then exits the cell 1 via the outlet 4, passes into the main outlet 34, and is discharged from there into the conduit 38. From here the process solvent is passed to the next bank of cells.

When the bank is changed from the process flow state to the flush flow state, the valves 40 and 41 are closed and the valves 44 and 45 are open. This shuts off the process solvent and causes the flush solvent to flow in the opposite direction through the cell.

The advantage of the bank of cells described above is that it provides a relatively simple valve system. The entire bank of cells has only four valves to reverse the flow through the individual cells. This makes the process more reliable and free to maintain. In addition, the price becomes low. In addition, a single gas vent is used for the entire bank of cells.

4 shows a flowchart of a plant comprising a plurality of banks of cells. Each bank is as described above with reference to FIG. Therefore, the same reference numerals are used for the same components as in FIGS. 1 to 3.

The individual cells in each bank 30 are connected in parallel and the inlet 3 and outlet 4 of each cell 1 are directly connected to the main inlet 32 and the main outlet 34, respectively. Next, the banks of cells are connected in series. Thus, process solvents containing metal ions are passed through each bank. Metal ions progressively peel off from the solvent as they pass through each bank of cells. Thus, the total number of banks of cells used in all plants depends on the initial grade of the feed solvent, the amount of metal to be removed and the target grade of the final product solvent.

Only one bank of cells is flushed at a time. This allows for continuous flow of process solvent through the plant with solvent by simply bypassing the bank of cells being flushed. The bank is flushed by passing the flush solvent in the opposite direction through the parallel cell. Flush solvent and suspended entrained metal powder are collected at the main inlet and then transferred to the settling tank by gravity.

The main advantage of the cell described above is that it produces a metal powder that can be easily handled separately from the copper tube. In addition, the metal powder is made to be formed automatically by the process apparatus rather than by manual handling. In prior art cells, the cell must be opened periodically to remove the large tube of copper, and then the cell is closed to resume the process. The above process is only non-invasive automatic electrorefining known to the applicant. As a result of these properties, they can be implemented and applied to large industrial plants.

The advantage of the cells described above is that the powder metal can be produced relatively efficiently. Since the cathode anode gap is relatively narrow, the current density becomes higher at a predetermined voltage, resulting in a higher yield of the metal product.

Another advantage of the plant described above is that a single main inlet and a single main outlet and a set of valves can be used to control the flushing of the cell to produce powdered metal.

Of course, the foregoing is only given to the illustrated examples of the invention, and all changes and modifications to the invention can be made by those skilled in the art without departing from the spirit and scope of the invention described.

Claims (38)

In a cell for electrorefining a metal in powder form from a solvent, A housing having an inlet at one end and an outlet at the opposite end; An anode extending axially through the housing; A cathode spaced outwardly from the anode and surrounding the anode, the cathode forming a flow passage having a gap of 5 mm to 25 mm between the anode and the cathode; Means for applying a potential difference between said anode and said cathode; Metal electrorefining cell. The method of claim 1, And means for passing a flush solvent in the opposite direction through the flow passage between the anode and the cathode to remove the plated metal on the cathode and to flush the metal out of the housing. Metal electrorefining cell. The method of claim 2, The flush solvent means comprises an outlet at an opposite end of the housing and an inlet at one end of the housing, through which the flush solvent is oriented into the flow passage, through which the flush solvent and removed metal are discharged from the cell. Metal electrorefining cell. The method of claim 3, wherein The outlet is oriented so that the flush solvent passed into the cell in the opposite direction is axially directed into the cell. Metal electrorefining cell. The method of claim 3, wherein An end of the anode is closed to orient the solvent around the anode and through the flow passage Metal electrorefining cell. The method according to any one of claims 1 to 5, One end of the cell is in the top orientation in use, the opposite end of the cell is in the bottom orientation in use, the inlet is located at or near the lower end, and the outlet is located at or adjacent the top end, Process solvent flows upward through the cell and flush solvent flows downward through the cell Metal electrorefining cell. The method according to any one of claims 1 to 5, The housing does not have mechanical means in the housing for removing solvent through the housing, and the housing does not have mechanical stripping means for mechanically peeling the plated metal from the cathode after the metal is deposited. Metal electrorefining cell. The method according to any one of claims 1 to 5, The cathode is cylindrical and the anode is also cylindrical but having a diameter smaller than the diameter of the cathode Metal electrorefining cell. The method according to any one of claims 1 to 5, The gap between the anode and the cathode is 10mm to 15mm Metal electrorefining cell. The method according to any one of claims 3 to 5, And further comprising a flow former having a conical configuration for directing flush solvent entering the cell through the outlet towards the flow passage between the cathode and the anode. Metal electrorefining cell. The method of claim 8, The cell further comprises means for guiding powder towards the inlet that cleans the cathode during the flush cycle Metal electrorefining cell. The method of claim 11, The guide means being formed by an inner surface of the housing which slopes inwardly downwards towards the inlet; Metal electrorefining cell. The method according to any one of claims 1 to 5, And further comprising mechanical cleaning means for crushing all dendritic crystals of the metal that may be formed in the flow path between the anode and the cathode. Metal electrorefining cell. The method of claim 13, And a support for supporting an anode in the housing. Metal electrorefining cell. The method of claim 14, The support portion mounted to one end of the housing and protruding axially into the housing, the support member supporting the anode, the inlet being eccentric from a central position to receive the support portion. Metal electrorefining cell. The method according to any one of claims 1 to 5, The housing includes a cylindrical body of stainless steel and an end cap of non-conductive material, each of the end caps defining a chamber axially outward of the cathode and anode. Metal electrorefining cell. The method of claim 16, The diameter of the cathode is 7.5 inches to 8.5 inches, the diameter of the anode is 6.5 inches to 7.5 inches, the difference between the diameter of the anode and the cathode is 0.5 inches to 1.5 inches Metal electrorefining cell. The method according to any one of claims 1 to 5, Means for foaming the gas upward through the flow passage between the cathode and the anode further comprising means for assisting in removing metal powder from the cathode Metal electrorefining cell. The method according to any one of claims 1 to 5, The housing extends vertically, the inlet is formed in the bottom end of the cell, the outlet is formed in the upper end of the cell, and a gap of 10 mm to 15 mm is formed between the cathode and the anode. Metal electrorefining cell. In a bank of cells, A plurality of cells as described in claim 1 arranged in parallel, A main inlet directly connected to each inlet of a cell in a bank for orienting parallel process solvent through the cell; A main outlet directly connected to each outlet of said cell for directing process solvent away from said cell, Flow reversal means for interrupting the flow of process solvent through the bank of cells when necessary and then passing the flush solvent through the main outlet and through the main inlet and through the main inlet in opposite directions. doing Bank of cells. The method of claim 20, The flow reversing means includes process solvent inlet valve means for opening and blocking the flow of process solvent into the main inlet, and process solvent outlet valve for opening and blocking the flow of process solvent exiting the main outlet in a downstream direction. Including means Bank of cells. The method of claim 21, The flow reversing means includes flush solvent inlet valve means for opening and blocking the flow of flush solvent into the main outlet, and flush solvent outlet valve means for opening and blocking the flow of flush solvent exiting the main inlet. doing Bank of cells. The method of claim 22, And control means for respectively controlling the opening and closing of said process solvent inlet valve means and outlet valve means, and said flush solvent inlet valve means and outlet valve means. Bank of cells. The method of claim 23, The control means for opening the flush solvent inlet and outlet valve means only when the process solvent inlet and outlet valve means are closed. Bank of cells. The method of claim 24, The control means opens the process solvent inlet and outlet valve means only when the flush solvent inlet and outlet valve means are closed. Bank of cells. The method according to any one of claims 23 to 25, The control means is a PLC controller Bank of cells. The method according to any one of claims 20 to 25, Means for venting gas from each of the cells of the bank; Bank of cells. The method of claim 27, The gas vent means comprising a vent operatively coupled to the main outlet Bank of cells. The method according to any one of claims 20 to 25, Each inlet of the cell connected to the main inlet is formed at each lower end of the cell Bank of cells. The method of claim 29, Each outlet of the cell connected to the main outlet is formed at an upper end of each of the cells. Bank of cells. The method of claim 30, The main inlet is located directly below the lower end of the cell, and the main outlet is located directly above each upper end of the cell. Bank of cells. A method of operating an electrorefining cell for electrorefining a metal from a metal ion containing process solvent, said cell having an inlet, an outlet spaced from said inlet, and a cylindrical cathode surrounding an anode, between said anode and said cathode. A method of operating an electrorefining cell, the method comprising: Passing the metal ion containing process solvent through the flow passage from the inlet to the outlet while simultaneously applying a voltage across the cathode and the anode to cause metal ions in the solvent to be plated as metal on the cathode; Periodically blocking the flow of the metal ion-containing process solvent through the cell and passing the flush solvent through the cell in the opposite direction, wherein the flush solvent is capable of removing the plated metal from the cathode and collecting the metal. Cleaning in the cell How electrorefining cells work. The method of claim 32, The flush solvent is passed into the cell through an outlet for the metal ion containing process solvent and the flush solvent is passed out of the cell through an inlet for the metal ion containing process solvent. How electrorefining cells work. The method of claim 33, wherein The outlet is at the top of the cell and the inlet is at the bottom of the cell. How electrorefining cells work. The method of claim 34, wherein Interrupting the flow of the flush solvent when the metal is removed from the cell, and then recovering the flow of the metal ion-containing process solvent through the cell to resume plating of the metal; How electrorefining cells work. 36. The method of claim 35 wherein Flushing the cell 1 to 6 hours after passing the flush solvent through the cell for 15 to 30 seconds to allow the metal ion-containing process solvent to pass through the cell; How electrorefining cells work. The method of claim 36, The flush solvent is pumped through the cell at a higher pressure than the metal ion containing process solvent, and the higher pressure helps to remove metal powder from the cathode. How electrorefining cells work. 38. A compound according to any one of claims 32 to 37, Collecting said particulate metal and said flush solvent in a conduit, which in turn is conveyed to a metal recovery plant. How electrorefining cells work.

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