US20140144788A1

US20140144788A1 - System and process for the continuous recovery of metals

Info

Publication number: US20140144788A1
Application number: US14/009,130
Authority: US
Inventors: Cameron Barton
Original assignee: FLSmidth AS
Current assignee: FLSmidth AS
Priority date: 2011-04-01
Filing date: 2012-04-02
Publication date: 2014-05-29
Also published as: MX2013011323A; CL2013002814A1; CA2831936A1; AU2012236120A1; WO2012135826A1; CN103582710A

Abstract

A system [100′] and process [100] for the continuous recovery of metals is disclosed. The system [100′] comprises a continuous acid wash system [10′], a holding tank [60], a continuous elution system [20′], a continuous electrowinning system [40′], a carbon regeneration system [30′], and a continuous carbon loading/adsorption system [70′]. The systems and methods disclosed overcome the disadvantages associated with current systems and processes which utilize batch process steps and equipment designed for batch processes. The systems [10′, 20′, 30′] are each configured to receive a continuous inflow of a solution or slurry and deliver a continuous outflow of a solution or slurry, without interruptions which are common with conventional metal recovery systems [9000′].

Description

BACKGROUND OF THE INVENTION

This invention relates to mining and metallurgical refining and more particularly to systems and processes for solvent extraction and electroextraction of metals.
To this end, there are generally two main processes available for precious metal concentration and recovery: zinc precipitation, and electrowinning. Zinc precipitation involves crushing and grinding ore containing the precious metal (e.g., gold), and then combining the ground ore with a water and caustic cyanide solution. The resulting mud-like pulp is moved to a settling tank where the coarser gold-laden solids move to the bottom via gravity, and a lighter first pregnant solution of water, gold, and cyanide moves to the top and is removed for further processing. The gold-laden solids are agitated and aerated in a separate agitated leach process where oxygen reacts to leach the gold into the caustic water and cyanide forming a second pregnant solution. The second pregnant solution passes through a drum filter which further separates remaining solids. The first and second pregnant solutions are combined with zinc to precipitate out the dissolved gold. The resulting precipitated gold concentrate may then be smelted to produce refined gold bar.
Electrowinning typically involves extracting a precious metal such as gold from an electrolyte. First, activated carbon is combined with a pregnant solution in a batch process step. The activated carbon adsorbs the precious metal contained within the pregnant solution, and becomes “loaded” with the precious metal. The loaded carbon is then descaled by sequentially washing it in three batch process steps to remove ore residue. First, the loaded carbon is moved to a washing tank and then the tank is filled with a dilute acid solution. The washing tank is then drained and the used dilute acid solution is pumped away and disposed of. The same washing tank is then filled with water to rinse remaining acid from the loaded carbon. The water becomes slightly acidic during this process. In a similar fashion to the dilute acid, the used slightly acidic rinse water is also drained from the washing tank, pumped away, and disposed of. Lastly, the tank is filled with a caustic solution, and the activated carbon is washed in the caustic solution. The used caustic solution is then drained from the tank, pumped away, and disposed of. An optional final water rinse step may be performed by again, filling the washing tank with rinse water or pH-neutral solution, rinsing caustic residue from the loaded carbon, and then draining the tank of the used rinse water/solution so that it may be pumped away for disposal.
After washing, the loaded carbon is removed from the washing tank and then added to a strip solution comprising water, a caustic substance, and cyanide to form a strip solution/loaded carbon slurry. The strip solution/loaded carbon slurry goes through an elution process where high temperatures and pressures are used to “re-leach” gold from the loaded carbon into the caustic strip solution to form an electrolyte solution. The electrolyte solution is then moved to a batch electrolytic cell where wire (e.g., reticulated) or plate cathodes collect deposited gold concentrate during electrolysis. After the batch electrowinning process, the cathodes are manually removed from the cell for cleaning, so that gold concentrate deposited thereon can be removed from the cathodes and readied for smelting. After cleaning, the cathodes are then manually replaced within the electrolytic cell, and the entire sequence of batch washing, elution, and electrowinning processes is repeated. Some cathodes (e.g., wire cathodes, due to their small interstices) are not re-useable and must be recycled after processing, thereby increasing overhead/operational costs.
FIG. 27 schematically illustrates a conventional metal recovery process 9000 as described above. Activated or reactivated carbon 9560 is suspended within a pregnant solution in a conventional batch carbon loading step 9700. The pregnant solution is generally formed by percolating a dilute cyanide solution through a heap leach pad of crushed mineral-laden ore (e.g., by way of a drip or spray irrigation having a concentration of about 0.5 to 1 pound of sodium cyanide, potassium cyanide, or calcium cyanide per ton of solution). Once the active carbon adsorbs the desired material (e.g., gold, silver, platinum, lead, copper, aluminum, platinum, uranium, cobalt, manganese) from the pregnant solution, it becomes “loaded” carbon 9570 and enters a batch acid wash process 9100 configured for descaling the loaded carbon 9570 as previously discussed.
FIG. 28 shows one example of a conventional batch acid washing system 9100′. Loaded carbon 9570 enters an acid wash vessel 9120 which receives dilute acid from a dilute acid tank 9140 via a pump 9132. Dilute acid overflow is captured by a sump pump 9150 which moves the overflow to a neutralizing tank 9160. Contents of the neutralizing tank 9160 may be moved to a secondary holding tank via a pump 9136. The conventional batch acid wash process 9100 continues by draining the acid wash vessel 9120 of dilute acid solution, and then filling the vessel 9120 with an aqueous rinse solution. Overflow of aqueous rinse solution is captured by sump pump 9150 which moves the overflow to a neutralizing tank 9160 and/or a holding tank. The process 9100 may continue by draining the vessel 9120 of aqueous rinse solution, and then filling the vessel 9120 with a caustic rinsing agent. Overflow of the caustic rinse may likewise be captured by sump pump 9150 and moved to a neutralizing tank 9160 and/or a holding tank (not shown).
After the loaded carbon 9570 is descaled, it leaves the batch acid washing process 9100 (via carbon transfer pump 9134) and enters a conventional batch (e.g. Zadra strip) elution process 9200. As shown in FIG. 29, a conventional batch elution process 9200 typically involves feeding descaled loaded carbon 9500 and/or loaded carbon directly from an adsorption system 9700 into a strip vessel 9240. Strip vessel 9240 is generally a large cylindrical tank of material suitable for holding reagents at an elevated pressure and temperature (e.g., 138 degrees C.-148 degrees C.). The descaled loaded carbon 9500 is maintained within the strip vessel 9240 at high temperatures and pressure in the presence of a caustic aqueous strip solution comprising cyanide. After a period of time, spent carbon 9550 is removed from the strip vessel 9240 (e.g., via carbon transfer pump 9232), and is moved to a carbon handling system or carbon regeneration system 9300′ or process 9300. Hot electrolyte solution 9421 is formed within the strip vessel 9240 as material previously adsorbed onto the loaded carbon leaches into the strip solution. The hot electrolyte solution 9421 is also removed from the strip vessel 9240 and passes through a heating skid 9250 or equivalent heat exchanger for cooling before entering a conventional batch electrowinning system 9400′ or process 9400. Cooling of hot electrolyte solution 9421 to form a lower temperature electrolyte solution 9530 is generally necessary to reduce the risk of flashing within a conventional batch electrolytic metal recovery cell 9420. The heating skid 9250 also serves to recycle energy by warming cooler barren solution 9540 which exits the electrolytic metal recovery cell 9420 (e.g., at about 66 degrees C.) and/or barren solution 9237 which exits the barren solution storing tank 9220 before re-entering the strip vessel 9240 to serve once again as a strip solution re-leaching agent. Warming of the cooler barren solution 9237, 9540 to form a hot barren solution 9239 may also be done using a heater in addition to, or in lieu of said heating skid 9250. One or more pumps 9234, 9236 are generally used to transfer barren solution back to the strip vessel 9240. Additional reagent from a reagent handling system and/or more pregnant solution may be added to barren solution tank 9220 as needed.
As shown in FIG. 30, electrolyte solution 9530 enters a conventional batch electrolytic metal recovery cell 9420 which operates in batch cycles. A series of parallel plate cathodes are placed within close proximity and the electrolyte solution 9530 is pumped in and agitated around the cathodes. Body portions of the cell 9420 carry an opposing charge with respect to the cathodes, and by virtue of electrolysis, ions contained in the electrolyte solution 9530 are subsequently deposited on the cathodes as a cathode sludge concentrate of the recovery metal or as a solid cathode plating. In operation, cathodes are typically removed simultaneously from the cell 9420 in a batch process step in order to collect the recovered metal. In instances where plate cathodes are used, the cathode may be flexed to delaminate and remove the hard cathode plating from the cathode. In other instances where higher deposition wire mesh (i.e., “reticulated”) cathodes are employed, the concentrate is separated from the cathode in a subsequent process and the cathodes are then recycled. Sludge concentrate may collect at the bottom of the cell 9420 and may be removed periodically. An electrowinning pump box 9440 and pump 9430 may be employed to temporarily store spent electrolyte (i.e., barren solution) which is removed from the cell 9420 between batches.
Problems associated with the abovementioned conventional acid wash systems 9100′ and processes 9100 are numerous. For instance, the systems utilize independent, non-continuous, “batch” process steps which require constant manpower, downtime, and energy (e.g, continually draining and refilling the same acid wash vessel 9120 with different rinsing agents). Moreover, such conventional batch acid wash processes 9100 typically discard expensive acid, caustic, and/or other reagents after each use. This increases overhead (e.g., purchasing costs, disposal costs) and creates unnecessary harm to the environment. Furthermore, every time a conventional acid wash vessel 9120 is drained and re-filled with a different rinsing solution, carbon (and precious minerals/metals attached thereto) may not be recovered due to system inefficiencies caused by heat, friction, increased pump residence time and exposure, an increased number of pipe elbows and valves, and the frequent discarding of spent rinsing solution which may still contain small amounts of loaded carbon and precious metal. In other instances (not shown), if separate vessels are used for each rinse step of the acid wash process, as many as four tanks and ten pumps may be required. This increases both initial plant overhead costs and overall plant footprint.
Problems associated with the described conventional batch elution process 9200 are also numerous. For instance, the process 9200 employs batch process steps which require constant manpower and energy (e.g., continually draining and refilling the strip vessel 9240 with new strip solution, hot barren solution 9239, and loaded carbon 9500 each time more electrolyte solution 9530 is needed for electrowinning 9400). This increases overhead costs (e.g., labor, maintenance), complicates production scheduling, and may cause harm to the environment. Furthermore, conventional metal recovery systems 9000′ are bulky and require large plant layout footprints as demonstrated by FIG. 23, when compared to a system 100′ for the continuous recovery of metals according to the invention (FIG. 22) which will be described hereinafter. Moreover, conventional elution systems have limited operating flow rates, temperatures, and pressures which drive up radiation losses and power consumption. Additionally, the electroextraction of metals using the conventional “batch” electrowinning processes 9400 described above requires intervals of non-production downtime of the electrowinning cell 9420 and significant physical labor, which may contribute to premature cathode wear and wasted electrolyte solution 9530.
The process of using zinc to precipitate precious metals out of pregnant solutions is also costly, may be less efficient for large-scale operations, works for only certain metals, and may result in less precious metal recovery.

OBJECTS OF THE INVENTION

It is, therefore, an object of the invention to provide an improved metal recovery system which is configured for continuous carbon loading/adsorption, continuous washing and stripping of loaded carbon, continuous electrolyte formation, continuous electrowinning, and continuous regeneration/re-activation, thereby avoiding the aforementioned problems associated with conventional batch metal recovery processes.
Another object of the invention is to improve the efficiency of a metal recovery process (e.g., by minimizing radiation losses, reducing power consumption, minimizing reagent consumption, and preventing carbon breakdown and electrolyte loss).
Yet another object of the invention is to prevent or minimize carbon loss and reagent waste.
Another object of the invention is to maximize total metal recovery.
Another object of the invention is to provide a metal recovery system which is configured to cost less and have a smaller footprint area than conventional metal recovery systems.
Another object of the invention is to provide a system and process for the recovery of metals which is configured to operate at higher flow rates, temperatures, and/or pressures than conventional processes.
Yet even another object of the invention is to reduce the percentage by weight of unrecovered metal present in spent electrolyte/barren solution.
These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the objects of the invention.

SUMMARY OF THE INVENTION

A system for the continuous recovery of metals is provided. The system comprises, in accordance with some embodiments of the invention, at least one of a continuous acid wash system configured for receiving a continuous, uninterrupted inflow of loaded carbonaceous particulate and delivering a continuous, uninterrupted outflow of descaled loaded carbonaceous particulate; a continuous elution system configured for receiving a continuous, uninterrupted inflow of a strip solution containing a descaled loaded carbonaceous particulate and delivering a continuous, uninterrupted outflow of electrolyte solution; and a continuous electrowinning system configured for receiving a continuous, uninterrupted inflow of electrolyte solution, delivering a continuous uninterrupted outflow of a barren solution, and continuously and uninterruptedly forming a cathode sludge concentrate. Each of the continuous acid wash system, the continuous elution system, and the continuous electrowinning system are generally configured to operate simultaneously without periodic interruptions which are common with conventional batch metal recovery processes.
In some embodiments, the system may comprise an integrated carbon regeneration system operatively connected to the continuous elution system. A continuous carbon loading/adsorpsion system may be operatively connected to and upstream of the continuous acid wash system. The continuous acid wash system may be operatively connected to the continuous elution system; for example, via a holding tank between said continuous acid wash system and said continuous elution system. One or more pumps may be provided to facilitate the transportation of slurry and solids within the system. In preferred embodiments, the continuous elution system is operatively connected to the continuous electrowinning system and comprises one or more screens or filters configured to prevent carbonaceous particulate from passing to the continuous electrowinning system.
The continuous acid wash system may comprise a chamber adapted for retaining a fluidization medium; an inlet adapted for receiving a feed containing loaded carbonaceous particulate; a fluidized bed distribution panel or other means adapted for fluidizing the loaded carbonaceous particulate in the presence of said fluidization medium; an opening adapted to pass loaded carbonaceous particulate and fluidization medium from the chamber; and a screen adapted to filter loaded carbonaceous particulate from a fluidization medium. The continuous elution system may comprise a splash vessel, a continuous elution vessel, and a flash vessel, wherein the splash vessel is operatively connected to the continuous elution vessel in series, the continuous elution vessel is operatively connected to the flash vessel in series, and the splash vessel is operatively connected to the flash vessel in parallel. The continuous electrowinning system comprises an electrolytic cell having a cell body configured to maintain electrolyte solution at a high pressure and/or temperature; at least one anode; at least one cathode; an inlet configured for receiving a continuous, uninterrupted influent stream of electrolyte solution; a first outlet configured for discharging a continuous, uninterrupted effluent stream of spent electrolyte solution; a second outlet configured for removing cathode sludge concentrate; and a residence chamber configured to continuously transfer electrolyte solution from said inlet to said first outlet and increase residence time of said electrolyte solution between said at least one anode and said at least one cathode. The residence chamber may comprise one or more channels which are configured to provide a forced flow of electrolyte solution therein which is strong enough to continuously dislodge and/or transport cathode sludge concentrate along said one or more channels and eventually out of said residence chamber.
The continuous elution vessel may comprise an influent manifold and an effluent manifold which communicate with the first outlet and inlet of the electrolytic cell, respectively, and may further comprise a fluidized bed and/or one or more internal baffles which are configured to torture flow paths and increase a residence time of loaded carbonaceous particulate therein. A valve configured to flash solution leaving the continuous elution vessel and entering the flash vessel may also be provided.
The continuous acid wash system may comprise at least one of an acid solution, an aqueous solution, and a caustic solution. The continuous elution system may comprise a solution containing at least one of a carbonaceous particulate loaded with a precious metal, an electrolyte solution, spent carbonaceous particulate, a caustic, an aqueous component, and cyanide. The continuous electrowinning system may comprise an electrolyte solution or cathode sludge concentrate. Each of the continuous acid wash system, the continuous elution system, and the continuous electrowinning system may be configured to increase a residence time, pressure, or temperature of solutions or slurries contained therein and may comprise a screen or filter element.
In some embodiments, the continuous acid wash system may comprise multiple washing vessels, each washing vessel comprising a chamber adapted for retaining a fluidization medium; an inlet adapted for receiving a feed containing a loaded carbonaceous particulate; a fluidized bed distribution panel or other means adapted for fluidizing and cleaning the loaded carbonaceous particulate with said fluidization medium; an opening adapted to pass loaded carbonaceous particulate and fluidization medium from the chamber; and a screen adapted to filter loaded carbonaceous particulate from fluidization medium. For instance, in some embodiments, the continuous acid wash system may comprise an acid wash tank containing an acidic fluidization medium, an aqueous rinse tank containing a substantially pH-neutral aqueous solution, and a caustic rinse tank containing an alkaline fluidization medium.
In some embodiments, the continuous acid wash system may comprise one or more recirculation tanks for collecting spent fluidization medium, and one or more weirs, channels, valves, or drains for capturing spent fluidization medium. The continuous electrowinning system may be configured for continuous and uninterrupted collection and removal of said cathode sludge concentrate and may comprise one or more channels defined between a cathode, an anode, and an insulator. The one or more channels may comprise portions of a helix, spiral, coil, compound curve, 3D-spline curve, figure-8, or serpentine shape and the cathode and anode may be formed as sleeves or tubes which are separated by said insulator. In some embodiments, the carbon regeneration system is operatively connected to both the continuous elution system and the continuous carbon loading/adsorpsion system, and the continuous carbon loading/adsorpsion system is operatively connected to said continuous acid wash system.
A process for the continuous recovery of a metal is also disclosed. The process, comprises, in accordance with some embodiments, continuously feeding a continuous wash system with particulate loaded with a metal; continuously washing said loaded particulate within the continuous wash system to descale the loaded particulate; continuously removing descaled loaded particulate from said continuous wash system; continuously loading a continuous elution system with said descaled loaded particulate; continuously removing electrolyte solution from said continuous elution system; continuously feeding a continuous electrowinning system with said electrolyte solution; continuously removing spent electrolyte solution from said continuous electrowinning system; and, continuously delivering said spent electrolyte solution to said continuous elution system; wherein each of the continuous wash system, the continuous elution system, and the continuous electrowinning system are configured to allow the above steps to be performed simultaneously, without the periodic interruptions required for conventional batch processes.
The process may further comprise continuously removing spent particulate from the continuous elution system; continuously feeding said spent particulate to a carbon regeneration system; continuously removing cathode sludge concentrate from the continuous electrowinning system; and/or forming said loaded particulate by continuously adsorbing metal onto said particulate in a continuous carbon loading/adsorption system which is similar to or identical to said continuous wash system. The particulate may be one of a carbonaceous particulate, a polymeric adsorbent, or an ion-exchange resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 schematically illustrate a system and method for the continuous recovery of metals according to some embodiments;

FIG. 3 is a flowchart of a three-sequence continuous acid wash operation according to some embodiments;

FIGS. 4 and 5 outline steps of a continuous acid washing process according to some embodiments;

FIGS. 6 and 7 depict a washing tank which may be used in the acid wash process shown in FIGS. 1-5;

FIG. 8 shows an acid wash system comprising a plurality of the washing tanks depicted in FIGS. 6 and 7;

FIGS. 9 and 12 schematically illustrate a system and method of continuous elution according to some embodiments;

FIG. 10 is an isometric view of a continuous elution system according to some embodiments;

FIG. 11 shows a side cutaway view of the continuous elution system of FIG. 10; FIGS. 13 and 19 schematically illustrate a system and method of continuous electrowinning according to some embodiments;

FIG. 14 shows a top plan view of a continuous electrowinning system according to some embodiments;

FIGS. 15 and 16 are vertical and isometric cutaway views, respectively, of a continuous electrowinning system taken on line XV-XV in FIG. 14;

FIG. 17 is a detailed view of FIG. 15, showing the particulars of an inlet according to some embodiments;

FIG. 18 is a transverse cutaway view of an electrowinning cell along line XVIII-XVIII in FIG. 14;

FIG. 20 shows a process for regenerating/reactivating spent carbon according to some embodiments;

FIGS. 21 and 22 show a system for the continuous recovery of metals;

FIG. 23 shows a conventional batch system for the recovery of metals;

FIG. 24 shows an alternative to the washing tank shown in FIGS. 6-8 or an apparatus to be used for continuous carbon loading/adsorption;

FIG. 25 shows a detailed isometric view of the chamber shown in FIG. 24;

FIG. 26 is a cutaway view of the chamber shown in FIG. 25;

FIG. 27 shows a conventional system for the recovery of metals.

FIG. 28 shows a conventional acid wash process;

FIG. 29 shows a conventional batch elution process; and,

FIG. 30 shows a conventional batch electrowinning process.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 and 2, a plant system 100′ or process 100 for the continuous recovery of a metal from mined ore may comprise, in accordance with some embodiments of the invention, a continuous acid wash system 10′ or process 10, a continuous elution system 20′ or process 20, a continuous electrowinning system 40′ or process 40, a continuous carbon regeneration system 30′ or process 30, and a continuous carbon loading/adsorption system 70′ or process 70. Activated/reactivated carbon 56 (which may be derived for example, from coconut shells or charcoal), or alternatively, an equivalent particulate substance such as loaded polymeric adsorbent or loaded ion-exchange resin, is subjected to a continuous carbon adsorption process 70 where it spends a time of residence suspended in a pregnant solution which contains a dissolved target recovery metal such as gold, silver, copper, aluminum, platinum, uranium, chromium, zinc, cobalt, manganese, or lead. The continuous carbon loading/adsorption system 70′ or process 70 may comprise, for example, an apparatus as shown in FIGS. 6 and 7 or FIGS. 24-26 which serves to fluidize the activated/reactivated carbon 56 within the pregnant solution. Once the carbon 56 becomes loaded with the target recovery metal, it undergoes a continuous acid wash process 10. Descaled loaded carbon 50 leaving the continuous acid wash process 10 enters a holding tank 60 filled with a strip solution containing one or more reagents (e.g., water, caustic, and cyanide) to form a slurry 51 of strip solution and descaled loaded carbon 50. The slurry 51 enters a continuous elution process 20 where the temperature and/or the pressure of the slurry 51 is increased and the target recovery metal previously adsorbed by the carbon is re-leached into the strip solution thereby forming an electrolyte solution 53 which may be used for a continuous electrowinning process 40. Barren solution (i.e., spent electrolyte) 54 leaving the continuous electrowinning process 40 is returned to the continuous elution process 20 and/or the holding tank 60 for re-use. A solids fraction 55 of spent carbon, depleted of its target recovery metal via the continuous elution process 20, moves to a carbon regeneration process 30 for reactivation before being re-used in the continuous carbon loading/adsorption process 70.
As shown in FIGS. 2-5, a continuous acid wash process 10 may generally comprise the steps of: feeding 1004 loaded carbon 57 into a continuous acid wash system 10′, fluidizing 1006 incoming loaded carbon 57 in a dilute acid solution within a first acid wash tank 12, extracting 1008 loaded carbon from the acid wash tank 12, screening 1010 the extracted loaded carbon to remove the dilute acid solution, capturing 1012 dilute acid solution 57 c separated from the loaded carbon, optionally processing 1014 the captured dilute acid solution 57 c (e.g., filtering, additives, pH adjust), and recycling the dilute acid solution 57 c by feeding 1016 the dilute acid solution 57 c back into the acid wash tank 12. Acid-rinsed loaded carbon 57 a which has undergone an acid bath in acid wash tank 12 is fed 1018 into a second aqueous rinse tank 14 containing water or another pH-neutral aqueous rinse solution 57 d, and then fluidized 1020 in said aqueous rinse tank 14. The process 10 further comprises extracting 1022 rinsed loaded carbon 57 b from the aqueous rinse tank 14, screening 1024 the extracted rinsed loaded carbon 57 b to remove aqueous rinse solution 57 d, capturing 1026 separated aqueous rinse solution 57 d separated from the rinsed loaded carbon 57 b, optionally processing 1028 the captured aqueous rinse solution 57 d (e.g., filtering, additives, pH adjust), and recycling the aqueous rinse solution 57 d by feeding 1030 the aqueous rinse solution 57 d back into the aqueous rinse tank 14. Rinsed loaded carbon 57 b which has undergone washing in aqueous rinse tank 14 is fed 1032 into a third caustic rinse tank 16 containing a caustic rinse solution 57 e, and is then fluidized 1034 in said caustic rinse tank 16. The continuous acid wash process 10 further comprises extracting 1036 descaled loaded carbon 50 from the caustic rinse tank 16, screening 1038 the extracted descaled loaded carbon 50 to remove caustic rinse solution 57 e, capturing 1040 caustic rinse solution 57 e separated from the descaled loaded carbon 50, optionally processing 1042 the captured caustic rinse solution 57 e (e.g., by filtering, providing additives, or adjusting pH), and recycling the caustic rinse solution 57 e by feeding 1044 the solution 57 e back into the caustic rinse tank 16. The continuous acid wash process 10 may comprise the step of providing one or more pumps 13 a, 13 b for re-circulating the rinsing solutions in each of the aforementioned tanks 12, 14, 16. Optionally, a fourth aqueous rinse cycle (not shown) may be provided, and one of ordinary skill in the art would acknowledge that any one or more of the aforementioned washing steps may be repeated or alternated.
Turning now to FIGS. 6 and 7, an acid wash tank 200 for cleaning and descaling a loaded particulate material may be employed for any portion of the continuous acid wash process 10. The loaded particulate material washed within said acid wash tank 200 may be of any particle size, shape, and density which can be fluidized by or suspended within a cleaning fluidization medium. The acid wash tank 200 is advantageously configured to descale active carbon particulate which has been loaded with a target metal, in preparation for creating an electrolyte for electrowinning. In such instances, the acid wash tank 200 may be filled with a fluidization medium comprising acid. Similar tanks 200′, 200″ may be used with fluidization mediums comprising water or caustic soda. Moreover, similar tanks may be used in yet other processes such as a continuous carbon loading/absorption process 70, wherein the particulate comprises activated/reactivated carbon 56, and the fluidization medium comprises a pregnant solution formed by percolating cyanide and/or other reagents through a heap leach pad of crushed ore containing a target metal or mineral.
According to some embodiments, acid wash tank 200 may comprise an acid wash tank having a first chamber 220, a first fluidized bed distribution panel 221, a first inlet 222, a first recirculation inlet 223 a, a first recirculation outlet 223 b, a first weir 224, a first screen 226, a first overflow outlet 227, a first discharge outlet 228, a first recirculation tank 229, a bottom wall 260, an inner tubular wall 266, an outer tubular wall 268, and a first channel 282 defined between the inner tubular wall 266 and outer tubular wall 268 adjacent the first weir 224. The first screen 226 serves to filter an incoming feed by separating its liquid fraction (e.g., spent pregnant solution, fluidization medium, or transport fluid) from its solid particulate fraction (metal-laden loaded or reloaded carbon). The liquid fraction drained from the particulate is maintained in the first recirculation tank 229 and may be removed through first recirculation outlet 223 b. The first recirculation outlet 223 b may be sealed during operation, coupled to a holding tank, coupled to a drain, coupled to a sump pump, or otherwise configured to feed an upstream or downstream process.
In some embodiments, as shown in FIG. 8, a continuous acid wash system 10′ may comprise one or more separate washing tanks 200, 200′, 200″ connected in series in order to provide flexibility in customizing plant layout and/or reduce overall footprint. In some instances, the tanks 200, 200′, 200″ may comprise similar or identical design characteristics, each containing different fluidization mediums. For example, in some embodiments, a first tank 200 may comprise an acid wash tank containing a strong or dilute acid solution 57 c, whereas second 200′ and third 200″ tanks may comprise aqueous and caustic rinsing tanks containing aqueous 57 d and caustic 57 e rinsing agents, respectively. While not required, tanks 200, 200′, and 200″ may be constructed as “universal” or “interchangeable” tanks. Moreover, tanks 200, 200′, 200″ may be configured with tubular (e.g., cylindrical pipe or prismatic extrusion) shapes as shown in order to reduce manufacturing costs. Any one or more of tanks 200, 200′, and 200″ may be replaced with a tank of dissimilar scale or a tank 2000 as shown in FIGS. 24-26, which will be described hereinafter.
A first fluidization medium comprising a dilute acid or anti-scaling agent solution may occupy the first acid wash tank 200. In some embodiments, the first fluidization medium may comprise a solution of 1-10% vol/vol mineral acid, such as nitric acid or hydrochloric acid configured to dissolve carbonate scale. In use, incoming loaded/reloaded carbon 57 moves over the first screen 226 and flows into the first chamber 220 of the first acid wash tank 200 via the first inlet 222. Fluid which may be present with the incoming loaded/reloaded carbon 57 is drained and enters the first recirculation tank 229. The screened loaded carbon subsequently falls downwardly along the first screen 226 and towards the first fluidized bed distribution panel 221 and is fluidized by the first fluidization medium. The first fluidization medium enters the first recirculation inlet 223 a and passes through distribution panel 221. Clarified first fluidization medium rises above the highest suspended level of loaded carbon within the first acid wash tank 200 and pours over the first weir 224 and into the first channel 282. Thereafter, clarified first fluidization medium exits the first acid wash tank 200 via outlet 227 and optionally feeds the first recirculation inlet 223 a and first fluidized bed distribution panel 221. One or more pumps 13 a may be provided between outlet 227 and inlet 223 a.
A slurry of acid-rinsed loaded carbon 57 a and residual first fluidization medium exits the first acid wash tank 200 through the first discharge opening 228 and enters a second aqueous rinse tank 200′ through a second inlet 232. The acid-rinsed loaded carbon 57 a may be conveyed to the tank 200′ using only gravitational forces, or the acid-rinsed loaded carbon 57 a may be conveyed to the tank 200′ using one or more slurry pumps (not shown). A second fluidization medium such as a substantially pH-neutral aqueous scrubbing solution or a hot water may occupy the second aqueous rinse tank 200′. In use, the acid-rinsed loaded carbon 57 a and first fluidization medium moves over a second screen 236 or equivalent filter and then flows into the second chamber 230 for pre-soak. The second screen 236 serves to separate residual first fluidization medium liquid from the acid-rinsed loaded carbon 57 a, wherein drained first fluidization medium is maintained in a second recirculation tank 239 and may be removed through second recirculation outlet. The second recirculation outlet 233 b may be coupled to a holding tank, a filtering apparatus, or an upstream or downstream process. For instance, as schematically indicated by the dotted line path of dilute acid solution 57 c′, the second recirculation outlet 233 b may be operatively connected to the first recirculation inlet 223 a to fluidize loaded/reloaded carbon 57 within the first washing tank 200. Though not shown, one or more pumps may be disposed between the outlet 233 b and inlet 223 a.
After passing over the second screen 236, acid-rinsed loaded carbon 57 a subsequently falls towards a second fluidized bed distribution panel 231 and is fluidized within the second chamber 230 by a flow of second fluidization medium entering the second recirculation inlet 233 a and passing upwards through panel 231. Clarified second fluidization medium free of loaded carbon particulate rises above a suspended level of acid-washed loaded carbon and pours over a second weir 234 and into a second channel 284, where it exits the second aqueous rinse tank 200′ via outlet 237 and optionally feeds the second recirculation inlet 233 a and second fluidized bed distribution panel 231 as schematically illustrated by dotted line path taken by aqueous rinse solution 57 d.
A slurry of rinsed loaded carbon 57 b and second fluidization medium exits the second washing tank 200′ through second discharge opening 238 and enters a third washing tank 200″ through a third inlet 242. The rinsed loaded carbon 57 b may be conveyed to the third caustic rinse tank 200″ using only gravitational forces, or the rinsed loaded carbon 57 b may be conveyed to the tank 200″ using one or more pumps (not shown). A third fluidization medium such as a caustic rinse solution may occupy the third washing tank 200″. For example, the third fluidization medium may comprise an amount of sodium hydroxide (NaOH) or potassium hydroxide (KOH) between 0.5% and 5% wt, for instance 1% wt. The third fluidization medium may comprise other reagents, for instance 1-10% wt sodium cyanide (NaCN). The third fluidization medium may be heated (e.g., 20-100 degrees C.). In use, a slurry of rinsed loaded carbon 57 b and second fluidization medium flows over a third screen 246 or equivalent filter and into the third chamber 240. The third screen 246 serves to filter the slurry by separating its second fluidization medium liquid fraction from its rinsed loaded carbon 57 b solid fraction. The separated second fluidization medium is maintained in a third recirculation tank 249. The second fluidization medium may be removed from the tank 249 via a third recirculation outlet 243 b which may be coupled to a holding tank, filtering apparatus, or one or more upstream or downstream processes. For instance, as schematically indicated by path taken by aqueous rinse solution 57 d′, the third recirculation outlet 243 b may be operatively connected to the second recirculation inlet 233 a in order to help fluidize particulate within the second washing tank 200′. Though not shown, one or more pumps may be disposed between the outlet 243 b and inlet 233 a. In some instances, outlet 243 b and inlet 233 a may be operatively connected to a plant water system.
After passing over third screen 246, twice-rinsed loaded carbon particulate subsequently falls towards a third fluidized bed distribution panel 241 and is fluidized within the third chamber 240 by a flow of third fluidization medium entering the third recirculation inlet 243 a and passing through the panel 241. Clarified third fluidization medium rises above the highest level of suspension of the loaded carbon fluidized within the tank 200″ and pours over a third weir 244 and into a third channel 286, where it exits the caustic rinse tank 200″ via outlet 247 and optionally feeds the third recirculation inlet 243 a as indicated by the dotted line path taken by caustic rinse solution 57 e.
A slurry of caustic-rinsed, descaled loaded carbon 50 and third fluidization medium exits the third caustic rinse tank 200″ through third discharge opening 248 and may be subsequently screened or filtered for further processing. After leaving the tank 200″, de-scaled loaded carbon 50 within the slurry may be separated from the third fluidization medium liquid fraction by a screen or filter (not shown) and then added to a strip solution of water, caustic, and cyanide in a holding tank 60 for use in downstream continuous elution 20 and electrowinning 40 processes.
The continuous acid wash system 10′ shown and described, when used, reduces or eliminates the need to continually purchase and replace lost quantities of carbon particulate, water, caustic, acid, and/or other anti-scaling agents. System 10′ also significantly reduces the amount of spent solution and carbon requiring disposal and reduces the potential for environmental harm.
It should be known that the particular features and suggested uses of the continuous acid wash system 10′ described herein are exemplary in nature and should not limit the scope of the invention. For example, fluidized bed portions 221, 231, 241 may be replaced with, or used in combination with one or more mechanical or forced air agitators (not shown) to suspend loaded carbon particulate in fluidization medium. Moreover, the number of chambers 220, 230, 240 per system 10′ may be greater or less than what is shown. In some embodiments, the relative sizes, dimensions and/or volumes of chambers 220, 230, 240 may vary. In other embodiments, the chambers 220, 230, 240 may be dimensioned and proportioned similarly. Additionally, one or more tanks 200, 200′, 200″ may be placed in parallel with others in order to increase throughput. For example, a third caustic rinse tank 200″ of a system 10′ may be directly or indirectly coupled to a plurality of upstream aqueous rinse tanks 200′. Multiple tanks 200 may replace any one of the single tanks 200, 200′, 200″ in system 10′ by splitting inlets 222, 223 a; 232, 233 a; 242, 243 a and/or outlets 223 b, 227; 233 b, 237; 243 b, 247. Moreover, any one chamber 220, 230, 240 may be compartmentalized into multiple chambers. As previously stated, the system 10′ or portions thereof may be used to continuously load activated carbon in a continuous carbon loading/adsorption process 70. For example, infeed particulate may comprise activated or reactivated carbon and the first, second, and third fluidization mediums may comprise a pregnant solution (e.g., sodium cyanide (NaCN) solution containing a dissolved precious metal).
FIG. 9 illustrates a continuous elution process 20 according to some embodiments. A feed slurry 51 of strip solution and descaled loaded carbon 50 is moved to a splash vessel 22 via gravity or one or more pumps 23. The splash vessel 22 increases the temperature and/or pressure of incoming slurry 51 and delivers the hot pressurized slurry 51 a to a continuous elution vessel 24. In the continuous elution vessel 24, target metal previously adsorbed onto the loaded carbon is leached into the strip solution to form an electrolyte solution 53. The electrolyte solution 53 is filtered by one or more screens to remove spent carbon and non-stripped loaded carbon from the electrolyte solution 53, before it is moved to a continuous electrowinning process 40. Electrolyte solution 53 may be conveyed to the continuous electrowinning process via an effluent manifold 28 b provided on the continuous elution vessel 24. Spent slurry 51 c of strip solution and spent carbon is flashed by a valve 29 and enters into a flash vessel 25 where steam is captured and returned to the splash vessel 22 via a steam return 21 to help heat and pressurize the splash vessel 22 in an efficient manner. The resulting concentrated spent slurry 51 d is separated into solid 55 and liquid 52 fractions using a dewatering screen 26. The liquid fraction 52 of concentrated spent slurry 51 d may be returned to holding tank 60, and the solids fraction 55 of the concentrated spent slurry 51 d (i.e., spent de-watered carbon) may be sent to a carbon regeneration process 30 for reactivation. Barren solution 54 returning from a continuous electrowinning process 40 is generally heated with an immersion heater 27 and then sent back to the continuous elution vessel 24 via one or more pumps 23 and an influent manifold 28 a.
FIG. 10 shows a continuous elution system 20′ according to some embodiments. The continuous elution system 20′ generally comprises a first splash vessel 22, a second continuous elution vessel 24, and a third flash vessel 25 connected in series via piping sections, and a steam return 21 extending between the splash 22 and flash 25 vessels in parallel. One or more pumps 23 may be provided at various portions of the system 20′ in order to facilitate flows to, from, and between the vessels 22, 24, 25, other parts of the system 20′, and/or other portions 10′, 30′, 40′ within a system 100′ for the continuous recovery of metals.
As shown in FIG. 11, the continuous elution vessel 24 comprises a fluidized bed distribution panel 320 which separates a residence chamber 340 from a fluidizing chamber 350. One or more baffles 318 may be provided within the residence chamber 340 in various configurations (e.g., number, angle, spacing, geometry), in order to increase the residence time of incoming hot pressurized slurry 51 a within the continuous elution vessel 24. The one or more baffles 318 may be parallel and staggered to create a serpentine flow path 51 b of hot pressurized slurry 51 a. The baffles 318 may be parallel, non-parallel, staggered at a single predetermined angle, or disposed in alternating fashion with each baffle oriented in a different predetermined angle. It should be understood that other baffle patterns and arrangements may be used without limitation, and that the shapes, porosities, and/or textures of baffles 318 may differ from what is shown. For example, any one or more of the baffles 318 may comprise folds, bends, curves, corrugations, openings, lattice structures, or the like.
Slurry flowing within the continuous elution vessel 24 may contain incoming hot pressurized slurry 51 a and barren solution 54 leaving a continuous electrowinning system 40′ or process 40. Fluidizing chamber 350 may be fed by an influent manifold 28 a connected to the continuous elution vessel 24 via one or more influent ports 326 having influent port mounts 322. Alternatively, the influent manifold 28 a may instead be connected directly to the one or more sidewalls 310 of the continuous elution vessel 24. A stream of barren solution 54 flows into the continuous elution vessel 24 via the influent manifold 28 a. The stream enters and fills the fluidizing chamber 350 and flows through fluidized bed 320 to help fluidize and suspend carbon particulate within the residence chamber 340 as it travels along the serpentine flow path 51 b.
An effluent manifold 28 b is also provided to the continuous elution vessel 24 to extract an electrolyte solution 53 from the residence chamber 340 and deliver said electrolyte solution 53 to a continuous electrowinning system 40′ or process 40. Effluent manifold 28 b comprises one or more effluent manifold ports, which may be provided with effluent manifold port mounts for ease of connection to the continuous elution vessel 24. Similarly to the influent manifold 28 a, the effluent manifold 28 b may be connected directly to the one or more sidewalls 310 of the continuous elution vessel 24, or may be connected to the vessel 24 via one or more effluent ports 316 having effluent port mounts 312.
While in the residence chamber 340 of the continuous elution vessel 24, loaded carbon is exposed to strip solution reagents under high temperature and high pressure conditions. The reagents in the strip solution act to strip the loaded carbon of its previously adsorbed metal contents (e.g., gold), and “re-leach” it into the solution to form an electrolyte solution. One or more screens or filters 324 may be provided between the residence chamber 340 and the effluent manifold 28 b in order to extract a clarified stream of electrolyte solution 53 from the continuous elution vessel 24 and/or prevent carbon particulate from passing downstream of the effluent manifold 28 b. In some embodiments, as shown, the placement of said screens or filters 324 may be at the interface between the effluent ports and the one or more sidewalls 310 of the continuous elution vessel 24. However, the screens or filters 324 may be provided in other locations without limitation, for instance: within the effluent manifold 28 b, within the continuous elution vessel 24, at the interface between the effluent manifold 28 b and mounts 312, or downstream of said effluent manifold 28 b. It should be known that one or more seals or gaskets (not shown) may be placed between the influent 28 a or effluent 28 b manifolds and the continuous elution vessel 24.
Fluidized carbon and solution within residence chamber 340 continues to move along the serpentine flow path 51 b until it is either removed through effluent manifold 28 b to be used as electrolyte, or passes through outlet 328. The outlet 328 may comprise an outlet mount 330 and/or an outlet seal 329 for connecting to a valve 29. The valve 29 may be of any sort known in the art, such as a ball or cone valve without limitation, and one would appreciate that the valve may be separately coupled to, or formed integrally with either one or both of the continuous elution vessel 24 and the flash vessel 25. Moreover, additional piping sections may be added between the second outlet 328 and the valve 29 if the distance between the continuous elution vessel 24 and the flash vessel 25 is large.
The stream of hot pressurized spent slurry 51 c exiting the continuous elution vessel 24 “flashes” as it passes through the valve 29. The resulting mixture of gas vapors, fluids, and solids enters the lower pressure flash vessel 25, where heated steam is diverted back to the splash vessel 22 via steam return piping 21. Unvaporized spent solution and spent carbon leave the flash vessel 25 in a stream of concentrated spent slurry 51 d. The concentrated spent slurry 51 d may comprise a barren solution liquid fraction 52, and a solids fraction 55 of spent carbon substantially-free of previously-adsorbed precious metal (e.g., gold). As previously mentioned, the stream of concentrated spent slurry 51 d may be subsequently screened or filtered by a dewatering screen 26.
In the embodiment shown, a liquid fraction 52 of the concentrated spent slurry 51 d is separated from the solid fraction 55 by dewatering screen 26 and returned to the holding tank 60 for re-use as strip solution. One or more pumps (not shown) may be provided to move the liquid fraction 52 to the holding tank 60. The solids fraction 55 of dewatered spent carbon is sent to a carbon regeneration process 30 comprising a regeneration kiln 35 or other means for reactivating the carbon. Dewatering screen 26 may be provided as a two-stage screen, wherein a first stage removes a majority of the liquid fraction 52 from the spent carbon solids fraction 55, and a second stage removes residual caustic and/or cyanide from the solids fraction 55 of spent carbon before it enters a regeneration kiln 35 or wash vessel. Accordingly, equipment in the carbon regeneration system 30′ is not damaged.
FIG. 12 schematically illustrates a continuous elution process 20 according to some embodiments. First, a slurry 51 of descaled loaded carbon 50 and a caustic strip solution comprising water and cyanide is produced 1048. The slurry 51 may be formed and stored in a holding tank 60. The slurry 51 is then pumped 1050 into the splash vessel 22 which is configured to elevate the temperature and/or pressure of the descaled loaded carbon/strip solution slurry 51. After increasing the temperature and/or pressure 1052 of the slurry 51 in the splash vessel 22, a hot pressurized slurry 51 a of loaded carbon/strip solution is formed and moved 1054 from the splash vessel 22 to the continuous elution vessel 24. The hot pressurized slurry 51 a is kept within the vessel 24 for an increased residence time 1056, for instance, by providing a fluidized bed 320 alone or in combination with a plurality of baffles 318 in order to elongate the physical travel path of the hot pressurized slurry 51 a between the inlet 304 of the vessel 24 and the outlet 328. The physical travel path may be for instance, a serpentine flow path 51 b as shown.
During its time of residence within the continuous elution vessel 24, the loaded carbon in the hot pressurized slurry 51 a is stripped of its adsorbed precious metal by reagents in the caustic strip solution. Accordingly, the caustic strip solution dissolves the precious metal into itself thereby forming an electrolyte solution 53. The electrolyte solution 53 is screened to remove carbon particulate therefrom and is extracted 1064 from the continuous elution vessel 24. Subsequently, the electrolyte solution 53 is fed 1066 to a continuous electrowinning system 40′ (e.g., into a continuous electrolytic metal extraction cell 42) for precious metal recovery. During the electrowinning process 1068 (see FIG. 19), barren solution 54 is continuously removed 1070 from the continuous electrowinning system 40′ and pumped 1072 back into the continuous elution vessel 24 either directly, or indirectly (e.g., via a barren solution holding tank (not shown) or immersion heater 27).
Solution and carbon are continuously removed from the continuous elution vessel 24, and the liquid fraction of the solution “flashed” or at least partially vaporized 1058 with a valve 29 before entering the flash vessel 25. The process 20 further comprises recovering 1060 heated steam from the rapid evaporation of exiting spent slurry 51 c, and piping 1062 the steam back to the splash vessel 22 in order to efficiently increase 1052 the temperature and/or pressure of the first vessel 22. Concentrated spent slurry 51 d is removed 1074 from the flash vessel 25, and then dewatered 1076 to separate the spent liquid fraction 52 from the spent solids fraction 55. The solids fraction 55 comprises dewatered carbon which is sent 1078 to a carbon regeneration system 30′, and the spent liquid fraction 52 of the concentrated spent slurry 51 d is sent 1080 to the holding tank 60 for re-use.
It should be known that the particular features and suggested uses of the continuous elution systems 20′ and processes 20 shown and described herein are exemplary in nature and should not limit the scope of the invention. For example, fluidized bed 320 may be replaced with, or used in combination with one or more mechanical agitators (not shown) to suspend loaded carbon particulate. Moreover, the number of baffles 318 in the continuous elution vessel 24 may be greater or less than what is shown, in order to provide the residence times and flow rates required for a particular process. Additionally, one or more additional vessels 22, 24, 25 may be added to a continuous elution system 20′ and placed in series or parallel with other vessels 22, 24, 25 to increase throughput. For example, two or three continuous elution vessels 24 may be directly or indirectly coupled to each other in parallel, and placed in series between a single splash vessel 22 and a single flash vessel 25.
FIG. 13 shows a continuous electrowinning process 40 according to some embodiments. The process 40 comprises continuously providing an electrolyte solution 53, continuously feeding the electrolyte solution 53 to a continuous electrolytic metal extraction cell 42, extracting cathode sludge concentrate 53 f from the cell 42 in a sludge removal stream 53 g, continuously extracting barren solution 54 from the cell 42 and using said barren solution 54 to feed a continuous elution vessel 24 within a continuous elution process 20.
As shown in FIGS. 14-18, the continuous electrowinning system 40′ largely comprises a continuous electrolytic metal extraction cell 42 comprising a cell body 406 having a first end 440, a second end 480, one or more sidewalls 482 extending therebetween, a base 404 having one or more mounts 402, at least one inlet 410 for receiving a continuous influent stream of a precious metal-containing electrolyte solution 53, at least one first outlet 420 for providing continuous egress of a spent electrolyte stream 53 d and barren solution 54 contained therein, and at least one second outlet 430 for providing egress of cathode sludge concentrate 53 f collected within the cell 42. The second outlet 430 may be configured for continuous egress of collected cathode sludge concentrate 53 f, or the second outlet 430 may be configured for intermittent egress of said collected cathode sludge concentrate 53 f. Within the cell body 406 is provided a first chamber 405, a second chamber 407, a third chamber 408, and a residence chamber 460 comprising one or more elongated channels 462. The channels 462 are configured to increase residence time of the electrolyte solution 53 and provide a forced flow electrolyte stream 53 b of electrolyte solution 53 therein which is strong enough to dislodge and/or displace cathodic sludge concentrate which forms and builds up within the channels 462. The one or more channels 462 may comprise, for example, a portion of a helix, double-helix, coil, spiral, serpentine, spline, compound curve, and may extend in curvilinear paths. In some embodiments, as shown, the residence chamber 460 may be concentrically situated between the first chamber 405 and the third chamber 408. The first chamber 405 may be configured to be devoid of electrolyte and/or cathodic sludge concentrate during operation, and may generally serve as a space-filler bounded between first end 440, inner anode 477, and baffle 450. The space filling first chamber 405 generally provides channels 462 within the residence chamber 460 with a larger radius, thereby increasing the overall effective length and total surface area of the channels 462 exposed to forced flow electrolyte streams 53 b contained therewithin. The third chamber 408 serves to temporarily hold and/or transport spent electrolyte streams 53 d from within the cell 42 to one or more first outlets 420. In some embodiments, to reduce material costs, the first end 440 may be configured as an annular panel having a central opening exposing the first chamber 405, rather than as a solid continuous circular panel as shown. The one or more first outlets 420 may be provided at an upper portion of the cell 42 where overflow is likely to be more clarified and free from cathode sludge concentrate.
Each channel 462 may be defined between at least one anode 474, at least one cathode 472, and one or more insulators 476 extending therebetween. In the particular embodiment shown, one or more anodes 474 and one or more cathodes 472 are provided as sleeve portions which alternate concentrically between an outer anode 479 and an inner anode 477 with each sleeve portion having a different radius. The anodes 474 and cathodes 472 are radially separated and maintain a uniform spacing by one or more spacing protuberances 473 projecting from said one or more cathodes 472. It should be understood, that while not shown, the one or more protuberances 473 may alternatively extend from the anodes 474 alone, or may extend from both anodes 474 and cathodes 472 without limitation. However, by providing protuberances 473 on the one or more cathodes 472, a small amount of extra cathodic surface area is provided for precipitating cathodic sludge concentrate out of the forced flow electrolyte stream 53 b during electrolysis. The one or more insulators 476 prevent short circuit between the negatively charged anodes 474 and positively charged cathodes 472 and may serve as flexible, tolerance-compensating gaskets which delineate the cross-sectional boundary of each channel 462 and build/concentrate the forced flow electrolyte stream 53 b within each channel 462.
As shown in FIG. 18, each anode 474 may communicate with one or more anode terminals 442. Anode terminals 442 may comprise, for example and without limitation, a fastener 442 a such as a pin or screw, a clamping member 442 b such as a nut, flange, or head, a terminal lead 442 c connected to a ground or power source, a conductive washer 442 d or other clamping member, an insulative bushing 442 e to prevent electrical currents from passing to surrounding portions of the cell 42, a thread or equivalent securing feature 442 f provided on said fastener 442 a, a conductive support 442 h comprising a complimentary thread or equivalent securing feature 442 g for communicating with said thread or equivalent securing feature 442 f, and a receiving portion 442 i provided within the conductive support 442 h for engaging and supporting one or more anodes 474. In the particular embodiment shown, anodes 474 are generally tubular cylindrical sleeves and therefore, receiving portions 442 i may be provided as small straight or generally arcuate slits. However, other equivalent interfaces are envisaged, particularly for non-cylindrical or non-tubular anodes 474 and cathodes 472. For example, instead of slits, receiving portion 442 i may comprise a plurality of conductive clamps, spring clips, or pegs extending from the support 442 h which straddle and secure an anode 474 thereto.
In some embodiments, the continuous electrowinning system 40′ may be provided with a cylindrical cell body 406, a flat circular upper first end 440, and a generally frustoconical lower second end 480. The frustoconical shape of the lower second end 480 generally aids in channeling collected heavy cathode sludge concentrate 53 f to the second outlet 430 for removal. The first end 440 may be secured to the cell body 406 via an annular flange 445 which may be electrically neutral or positively charged with the rest of cathodic cell body 406. The first end 440 may comprise a series of sandwiched panels, such as one or more ground or electrically-neutral panels 447, one or more anodic panels 444, and one or more insulative panels 446. In some embodiments the one or more insulative panels 446 may comprise a gasket, such as a polytetrafluoroethylene (PTFE) insulating gasket. One or more fasteners 441 or adhesives may be provided to secure the first end 440 to the body 406 and/or to secure sandwiched panels 444, 446, 447 together. For example, a series of fasteners 441 may be provided around a perimeter of the first end 440 to secure the first end 440 to the flange 445. The fasteners 441 may be insulated, for example, with a sheath, coating, bushing, or washer of non-conductive material such as high molecular weight polyethylene (HMWPE), polyvinylidene fluoride (PVDF), polypropylene, or polyvinylchloride (PVC). Moreover, the fasteners 441 may serve the dual purpose of securing the first end 440 to the body 406 and also securing sandwiched panels 444, 446, 447 together.
In use, an influent stream of electrolyte solution 53 at a higher-than-ambient pressure and temperature continuously enters the cell 42 via inlet 410. The electrolyte solution 53 may contain metal ions of copper, gold, silver, platinum, lead, zinc, cobalt, manganese, aluminum, or uranium, without limitation. The continuous electrowinning system 40′ is preferably maintained at a higher-than-ambient temperature (e.g., around 88 degrees Celsius) and/or pressure. The influent stream of electrolyte solution 53 may come from an upstream electrolyte holding tank (not shown), a continuous elution system 20′, or a combination thereof. In some embodiments, the inlet 410 may be formed from a portion of a pipe or tubing having one or more sidewalls 412 and may further comprise an inlet mount 414 having a flange, seal, valve, pipe fitting, or equivalent connector for integration with the continuous elution system 20′. Inlet 410 comprises one or more openings 413 (e.g., through said one or more sidewalls 412), which are configured to feed said one or more channels 462 of the residence chamber 460 with incoming electrolyte solution 53. Though not shown, a plurality of openings 413 may be provided per channel 462. In the event multiple channels 462 and a single inlet 410 is employed as shown, the influent stream of electrolyte solution 53 may be split into a plurality of dispersed influent streams 53 a, each entering different channels 462. Alternatively, while not shown, a separate inlet 410 may be provided for each channel 462. The openings 413 may be configured to provide uniform or non-uniform flow rates across each channel 462 or provide similar electrolyte residence times for each channel 462. As clearly shown in FIG. 17, one or more insulators 417 (e.g., an insulation pad) may be placed between one or more sidewalls 412 of the inlet 410 and the first end 440 of the cell body 460. The one or more insulators 417 may encircle the one or more openings 413 to ensure that incoming electrolyte solution 53 from dispersed influent streams 53 a does not form, plate, or sludge within the openings 413, particularly adjacent cathodes 472.
In some embodiments, channels 462 may be configured to allow the dispersed influent streams 53 a of electrolyte solution 53 to flow forcedly through the channels 462 in a forced flow electrolyte stream 53 b which follows a uniform helical or spiral path as shown. However, while not shown, the channels 462 may also be configured to direct the dispersed influent streams 53 a along straight paths, serpentine paths, compound curve paths, or complex 3D-spline curve paths so long as they can support a forced flow electrolyte stream 53 b therein and provide a sufficient residence time of electrolyte between an anode 474 and cathode 472.
Channels 462 may shrink or grow in circumference or change in overall or cross-sectional shape and/or size as they extend within the residence chamber 460; however, it is preferred that channels 462 remain uniform in cross-section, direction, and/or anode-cathode spacing throughout their entire length. While not shown, since channels 462 located at greater radial distances from the center of the cell 42 are longer and will generally have higher residence times than inner channels 462, the number of turns of inner channels 462 (e.g., channels adjacent inner anode 477 and first chamber 405) may be adjusted to be greater than the number of turns for outer channels 462 (e.g., channels more proximate the outer anode 479 and third chamber 408). In other words, while not shown, inner portions of residence chamber 460 may be greater in height than outer portions of residence chamber 460, in order to lengthen the effective length of inner channels 462 (adjacent the first chamber 405). Portions of baffle 450 adjacent the residence chamber 460 and third chamber 408 are generally open so as to allow channels 462 to continuously deliver spent electrolyte streams 53 d to the third chamber 408 and collected cathode sludge concentrate 53 f formed in the channels 462 to the second chamber 407.
As shown in FIG. 16, baffle 450 may comprise an anodic layer 452, a middle electrically-neutral insulator 454 to support said one or more anodes 474 and cathodes 472, and a support structure 456 for supporting the insulator 454 and anodic layer 452. The insulator 454 may be made of a chemically-robust material such as ultra-high molecular weight polyethylene (UHMWPE) and may be cruciform in shape as shown. A plurality of receiving portions 458 such as notches may be provided to the insulator 454 to hold, space, insulate, and support the one or more anodes 474 and cathodes 472; however, other holding means such as pegs, spring clips, or clamps may be provided. The insulator 454 may be connected to the support structure 456 with one or more fasteners, adhesives, or other connecting means, and the support structure 456 may be connected to the body 406 by conventional means such as bolting, forming, adhering, welding, or supporting on a flange or shelf. The anodic layer 452 may serve to close off the first chamber 405 and prevent electrolyte 53 in the forced flow electrolyte stream 53 b from entering said first chamber 405. In some embodiments, the support structure 456 may be a lattice structure such as a mesh screen or supporting member such as a crossbar which spans a width of the cell body 406. Support structure 456 is generally configured not to inhibit electrolyte flowing from the channels 462 to the third chamber 408, or inhibit the passage of cathode sludge concentrate 53 f to the second chamber 407.
As electrolyte solution 53 forcibly flows through the one or more channels 462 in the residence chamber 460, a large electric potential is placed between the one or more anodes 474 and one or more cathodes 472 in order to effectively “plate-out” sludge concentrate onto the one or more cathodes 472. However, by varying operating parameters such as residence time, electric current, electrolyte flow rate, temperature, pressure, electrolyte concentration/composition, and/or smoothness/material/coating of each cathode(s) 472, the channels 462 may be configured such that cathodic sludge concentrate initially forms on or adjacent to the one or more cathodes 472, but will not actually bond or “plate” to the cathodes 472 and will instead flush down the channels 462 and/or become suspended in the forced flow electrolyte streams 53 b. Any sludge concentrate that may settle to bottom of a channel 462 may also be washed down and eventually swept out of the channels 462 and into second chamber 407 by the forced flow electrolyte streams 53 b. Sludge concentrate may be flushed out of the one or more channels 462 by virtue of: gravitational forces acting on inclined surfaces, high flow rates of forced flow electrolyte streams 53 b passing through the one or more channels 462, increased turbulence within each channel 462, and/or by virtue of small cross-sectional areas provided to each channel 462.
After the forced flow electrolyte streams 53 b pass through the one or more channels 462, the outflow 53 c of the residence chamber 460 will generally comprise a liquid carrier component of barren solution 54 which is substantially-free of dissolved precious metal, and a solid precipitate component comprising cathodic sludge concentrate which has been discharged from the channels 462 by the forced flow electrolyte stream 53 b. The heavier solids may follow a sludge precipitate stream 53 e before settling in a mass of collected cathode sludge concentrate 53 f within the second chamber 407 adjacent the second end 480. Barren solution 54 travels via spent electrolyte stream 53 d into the third chamber 408 and continuously leaves the cell 42 through outlet 420. In embodiments where the cell body 406 is cathodic, some residual plating or cathodic sludge concentrate formation may occur within the third chamber 408 (for example, on or around inner portions of cathodic sidewall(s) 482). However, any cathode sludge concentrate 53 f formed within the third chamber 408 will typically settle and eventually end up in second chamber 407 with the rest of the collected cathode sludge concentrate 53 f.
The first outlet 420 may be formed from a portion of a pipe or tubing having one or more sidewalls 422 and may further comprise a first outlet mount 424 having a flange, seal, valve, pipe fitting, or equivalent connector for integration with a continuous elution system 20′. When in use, an effluent stream of barren solution 54 continuously leaves the cell body 406 through said first outlet 420 at which point it may enter a barren solution holding tank (not shown), be discarded, return to a continuous elution system 20′, or undergo further processing.
Captured cathode sludge concentrate 53 f may be removed from the cell 42 intermittently or continuously via second outlet 430. The underflow, or sludge removal stream 53 g of cathode sludge concentrate 53 f may proceed to a holding tank, be pumped away for further refining, or may be dumped into a container and transported to a smelter. In some embodiments, the second outlet 430 may be formed from a portion of a pipe or tube having one or more sidewalls 432 and may further comprise a second outlet mount 434 having a flange, seal, valve, pipe fitting, nozzle, tap, or equivalent connector for integration with a holding tank or smelting apparatus.
The cross-section of residence chamber 460 may vary, so long as one or more channels 462 therein are formed between at least one anode 474 and at least one cathode 472 which are separated from each other by one or more insulators 476. Channels may extend linearly (resembling an elongated pipe), helically, in a cascade of connected, horizontally-arranged, and vertically-displaced “figure-8s”, or in any continuous path in 3-D space which is configured to provide a “forced flow” of electrolyte solution. In order to assist with outgassing of air which could get caught in the channels 462 and also prevent the backup of precipitated sludge concentrate within the channels, it is preferred that the continuous path the channels follow in 3-D space be free of sharp bends, abrupt turns, overhangs, high spots, and/or tightly wound corners which may be prone to air capture and clogging. In some embodiments, a residence chamber 460 may comprise one or more channels 462 therein which simply extend as long straight pipe sections tilted at an angle with respect to horizontal.
FIG. 19 schematically illustrates a continuous electrowinning process 40 according to some embodiments. The process 40 comprises providing 1082 an electrolyte solution 53 having an elevated temperature or pressure with respect to ambient conditions. The electrolyte solution 53 may be produced from a continuous elution process 20 and may comprise water, cyanide, caustic, and a dissolved metal (e.g., gold, copper, silver, platinum, aluminum, lead, zinc, cobalt, manganese, or uranium) therein. The electrolyte solution 53 is continuously fed 1084 (e.g., at a predetermined flow rate) into a continuous electrolytic metal recovery cell 42 which is preferably maintained 1086 at a higher-than-ambient temperature and/or pressure. In some embodiments, the cell 42 may comprise a series of nested anode sleeves 474 and cathode sleeves 472, wherein adjacent sleeves have a different electrical potential or charge. In a preferred embodiment, the sleeves are spaced concentrically and radially evenly with respect to each other so that any two neighboring sleeves hold an opposite charge 1088. One or more insulators 476 may be placed between the anodes 474 and cathodes 472 to define a plurality of channels 462 (e.g., helical channels) and simultaneously prevent arcing between the anodes and cathodes. The process 40 further comprises subjecting 1090 the electrolyte solution 53 to a longer residence time within a continuous electrolytic metal recovery cell 42. This may be achieved by providing one or more elongated channels 462 between the anode 474 and cathode 472 sleeves, which extend in smooth, continuous, and uninterrupted helical paths. It should be known that residence time may also be increased by alternatively employing long tubular straight channels. Electrolyte solution 53 maintained within the channels 462 is forced through the channels 462 and walls thereof by small pressure differentials between the inlet 110 and the first 120 outlet and/or small pressure differentials between the inlet 110 and the second 130 outlet. As the electrolyte solution 53 moves through the channels 462, cathodic sludge concentrate precipitates out of the electrolyte solution 53 until the solution becomes weaker in concentration and eventually substantially-free of precious material 1092. Precipitating concentrate from the sludge precipitate stream 53 e is continuously collected 1094 within second chamber 407, and collected cathode sludge concentrate 53 f may be extracted 1098 continuously or intermittently or a combination thereof. A stream of barren solution 54 (which is substantially devoid of precious metal) is continuously extracted 1096 from the cell 42 via outlet 420, and may be fed to a continuous elution vessel 24 within a continuous elution process 20.
FIG. 20 shows a carbon regeneration process 30 according to some embodiments. A solids fraction 55 of concentrated spent slurry 51 d comprising spent de-watered carbon is sifted with a screen 32 to separate out spent carbon fines 55 b. The spent carbon fines 55 b are placed in a carbon fines holding tank 34. The remaining course spent carbon 55 a is sent to a regeneration kiln 35 (or other means for regeneration such as a chemical, steam, or biological process). Hot reactivated carbon 55 c is removed from the regeneration kiln 35 and quenched in a carbon quench tank 36. A slurry of cooled regenerated carbon and fluid moves to a dewatering screen 37 via pump 33. After passing through dewatering screen 37, dewatered activated/reactivated carbon 56 is moved to a continuous carbon loading/adsorption process 70. The fluid underflow, which comprises cool reactivated carbon slurry 55 d, is moved to the carbon fines holding tank 34.
FIG. 21 shows a continuous metal recovery system 100′ according to some embodiments of the invention comprising a continuous acid wash system 10′, a continuous elution system 20′, a continuous electrowinning system 40′, and a carbon regeneration system 30′. FIGS. 22 and 23 serve to compare scale plant layouts and overall footprints. FIG. 22 shows the system 100′ for the continuous recovery of metals according to FIG. 21 and FIG. 23 comprises a conventional system 9000′ for the batch recovery of metals using “batch” process steps. As can be seen from FIGS. 22 and 23, the system 100′ according to the invention is smaller in size than the conventional system 9000′ depicted in FIG. 23. In addition to smaller size, system 100′ is also more efficient and environmentally-friendly.
FIG. 24 shows an alternative to the washing tanks 200, 200′, 200″ shown in FIGS. 6-8. In the embodiment shown, an acid wash tank 2000 is provided, which may replace acid wash tank 200. Acid wash tank 2000 comprises a wash chamber 2020 having a fluidized bed panel 2021 spanning the length of the wash chamber 2020 with pore sizes smaller than the mean particle size of loaded/reloaded carbon, one or more adjustable mounts 2007, 2009 which may be individually raised, lowered, or pivoted on a rack or linkage (not shown for clarity) to change the inclination angle of the chamber 2020 with respect to a skid 2002, a recirculation inlet 2023 a provided below the fluidized bed panel 2021, and a recirculation outlet 2023 b provided above the fluidized bed panel 2021. Recirculation outlet 2023 b comprises one or more overflow outlets 2027, each provided with at least one washable/replaceable recycle screen 2008, which maintains loaded/reloaded carbon 57 within the chamber 2020 and filters exiting dilute acid solution 57 c. Recycle screens 2008 may be conveniently provided between bolted flange members of the overflow outlets 2027 and may comprise built-in peripheral gaskets. FIGS. 25 and 26 show more detailed views of the chamber 2020 shown in FIG. 24.
Recirculation inlet 2023 a may comprise one or more adjustable nozzles 2011 which serve to fluidize loaded/reloaded carbon 57. The nozzles 2011 may be individually or collectively angularly adjusted and “set” to a fixed angle, in order to: compensate for various inclinations of the chamber 2020, prevent buildup of loaded/reloaded carbon 57, and counteract backflow within the chamber 2020 caused by eddy currents surrounding interior baffles 2018. Chamber 2020 may, as shown, be constructed in clamshell form, with a number of fasteners 2004 connecting upper and lower clamshell portions together. One or more additional gaskets may be employed between the upper and lower clamshell portions to form a seal, or the fluidized bed panel 2021 itself may be provided with peripheral gasketing material properties to provide a seal between the upper and lower clamshell portions.
A first filter 2001 is provided at an inlet 2022 to the acid wash tank 2000. The first filter 2001 comprises a housing 2003 which serves to collects influent loaded/reloaded carbon slurry 57′, a first screen 2026 which serves to separate loaded/reloaded carbon 57 from carrier fluid 57 f present in the slurry 57′, a first filter outlet 2006 which serves to transfer strained loaded/reloaded carbon 57 from within the upper housing 2003 to the wash chamber 2020, a recirculation tank 2029 which collects carrier fluid 57 f separated from the liquid fraction of the influent slurry 57′, and one or more clamps 2005 which removably attach the housing 2003 to the recirculation tank 2029 with the first screen 2026 extending therebetween, thereby allowing periodic cleaning and/or replacing of the first screen 2026. Recirculation tank 2029 may be configured to continuously redistribute carrier fluid 57 f to a holding tank (not shown) or may simply comprise a valve for batch removal of the collected carrier fluid 57 f.
A second filter 2024, similar to the first filter 2001, is provided adjacent a first channel 2082 extending from the fluidized bed panel 2021 to an outside portion of the wash chamber 2020. First channel 2082 is configured to provide egress of acid-rinsed loaded carbon 57 a resting on/around/above fluidized bed panel 2021 after it has undergone a predetermined residence time of acid washing within the chamber 2020. The acid-rinsed loaded carbon 57 a is filtered by a second screen 2036, and the strained solids fraction of the acid-rinsed loaded carbon 57 a exits a discharge outlet 2028. The acid-rinsed loaded carbon exiting the discharge outlet 2028 may be captured and contained by a holding tank 2060 and subsequently transported (via pump 2030) to a downstream process (e.g., aqueous rinse cycle). Alternatively, the acid-rinsed loaded carbon exiting the discharge outlet 2028 may directly enter a downstream process (e.g., pour into another aqueous rinse tank 200′ without an intermediate holding tank 2060 and pump 2023). Holding tank 2060 advantageously serves as a buffer which maintains a level of process control and prevents too much carbon feed to downstream processes.
In use, replenished dilute acid solution 57 c′ (obtained by filtering acid-rinsed loaded carbon 57 a with second screen 2036) enters recirculation tank 2039 and is pumped to chamber 2020 via a pump 2030. The replenished dilute acid solution 57 c′ enters the recirculation inlet 2023 a and then passes upwards through fluidized bed panel 2021 via nozzles 2011. The replenished dilute acid solution 57 c′ suspends incoming loaded/reloaded carbon 57, and moves the loaded/reloaded carbon 57 through the chamber 2020 and around baffles 2011 for a predetermined residence time. The replenished dilute acid solution 57 c′ passes through recycle screens 2008 and filtered dilute acid solution 57 c re-enters the recirculation tank 2039 via recirculation outlet 2033 b. Residence time of the loaded/reloaded carbon 57 may be increased or decreased by adjusting the inclination angle of the chamber 2020 and/or adjusting the angular orientation of nozzles 2011. For a fixed, non-variable metal extraction process, the inclination angle of chamber 2020 and angular positions of nozzles may be preset by the manufacturer and permanently fixed in the optimum configuration to yield the most efficient residence time for said process.

Example 1

A water-based, loaded carbon slurry 57 comprising approximately 30-300 oz/ton gold and approximately 30% wt/wt, activated coconut shell carbon is delivered to a continuous acid wash system 10′. First, inorganic components, namely calcium and magnesium carbonate, are removed from the loaded carbon by fluidizing a bed of loaded active carbon with a dilute aqueous acid solution comprising approximately 1-5 wt % hydrogen chloride (HCl) and/or nitric acid (HNO₃) in an acid wash tank 12, 200. The loaded active carbon is continuously transferred from the acid wash tank to an aqueous rinse tank 14, 200′ where the loaded active carbon is fluidized and cleaned with water. The loaded carbon is subsequently continuously transferred from the aqueous rinse tank 14, 200′ to a caustic rinse tank 16, 200″. The pH of the loaded active carbon delivered to the caustic rinse tank is raised above 10 by a caustic solution comprising approximately 1-3 wt % sodium hydroxide.
The basic descaled loaded carbon 50 is fed continuously to a splash vessel 22 within a continuous elution system 20′ via a transfer medium of caustic strip solution comprising approximately 1 wt % caustic (NaOH) and 0.1 wt % cyanide (NaCN). The splash vessel 22 is generally held at an operating temperature between approximately 100 and 200 degrees Fahrenheit (° F.), and at a pressure of approximately atmospheric level. The loaded carbon is transferred from the splash vessel 22 to the continuous elution vessel 24, where the gold is removed from the carbon (i.e., gold dissolution). The continuous elution vessel 24 operates at roughly 300 degrees Fahrenheit (° F.), which temperature is achievable by elevating the strip solution pressure to roughly 70 psi (gauge). The continuous elution vessel 24 continuously discharges into a lower pressure flash vessel 25. A drop in pressure between the continuous elution vessel 24 and flash vessel 25 causes rapid flash vaporization of a portion of the effluent caustic strip solution. Steam generated is channeled to the splash vessel 22, thereby simultaneously heating the splash vessel 22 and cooling the flash vessel 25. Spent carbon, (e.g., comprising less than 1 oz/ton gold), is continuously moved out of the continuous elution system 20′ and into a regeneration process 30.
The approximately 300° F. pressurized caustic strip solution is filtered by one or more screens or filters 324 to remove barren carbon particulate and form electrolyte solution 53, which is then passed through a continuous electrolytic metal extraction (i.e., electrowinning) cell 42. The electrolyte solution 53 is forced (via the increased pressure provided by the continuous elution vessel 24) through at least one channel 462 having a fixed helical path between a cylindrical sleeve anode 474 and a cylindrical sleeve cathode 472. A voltage between approximately 2 and 4 volts is passed between the anode 474 through the electrolyte solution 53 and the cathode 472, thereby depositing cathode sludge concentrate 53 f on surfaces of the cathode 472. The velocity of the electrolyte solution 53 creates a forced flow electrolyte stream 53 b within the channel 462 which continuously washes the collected cathode sludge concentrate 53 f which may form and collect on the cathode's surfaces to the conical bottom of the cell 42, where it may be removed at the operator's leisure or continuously via a control valve.
A contractor or other entity may provide a system 100′ or process 100 for the continuous recover of metals in part or in whole as shown and described. For instance, the contractor may receive a bid request for a project related to designing a continuous metal recovery system 100′ or process 100, or the contractor may offer to design such a system 100′ or a process 100 for a client. The contractor may then provide, for example, any one or more of the devices or features thereof shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer. The contractor may subcontract the fabrication, delivery, sale, or installation of a component of the devices or of other devices used to provide such devices. The contractor may also survey a site and design or designate one or more storage areas for stacking the material used to manufacture the devices. The contractor may also maintain, modify, or upgrade the provided devices. The contractor may provide such maintenance or modifications by subcontracting such services or by directly providing those services or components needed for said maintenance or modifications, and in some cases, the contractor may modify an existing metal recovery process 9000 or system 9000′ with a “retrofit kit” to arrive at a modified process or system comprising one or more method steps, devices, or features of the systems 100′ and processes 100 discussed herein.
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. For example, particulates and carriers other than carbon (e.g., polymers or ion exchange resins) may be used with the disclosed systems and processes. Moreover, reagents other than water, cyanide, and caustic may be used to wash, descale, or strip the particulates. Furthermore, the disclosed systems and processes may be used to recover numerous types of materials including, but not limited to copper, gold, silver, platinum, uranium, lead, zinc, aluminum, chromium, cobalt, manganese, rare-earth and alkali metals, etc. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.


Reference numeral identifiers

10	Continuous acid wash process
10′	Continuous acid wash system
12	Acid wash tank
13	Pump
14	Aqueous rinse tank
16	Caustic rinse tank
20	Continuous elution process
20′	Continuous elution system
21	Steam return
22	Splash vessel
23	Pump
24	Continuous elution vessel
25	Flash vessel
26	Dewatering screen
27	Immersion heater
28a	Influent manifold
28b	Effluent manifold
29	Valve
30	Carbon regeneration process
30′	Carbon regeneration system
32	Screen
33	Pump
34	Carbon fines holding tank
35	Regeneration kiln
36	Carbon quench tank
37	Dewatering screen
40	Continuous electrowinning process
40′	Continuous electrowinning system
42	Continuous electrolytic metal extraction cell
50	Descaled loaded carbon (or caustic/basic slurry thereof)
51	Slurry of strip solution and descaled loaded carbon
51a	Heated and/or pressurized slurry
51b	Serpentine flow path of slurry
51c	Spent slurry
51d	Concentrated spent slurry
52	Liquid fraction of concentrated spent slurry
53	Electrolyte solution
53a	Dispersed influent stream
53b	Forced flow electrolyte stream
53c	Residence chamber outflow
53d	Spent electrolyte stream
53e	Sludge precipitate stream
53f	Cathode sludge concentrate
53g	Sludge removal stream
54	Barren solution (i.e., spent electrolyte)
55	Solids fraction of concentrated spent slurry (e.g., de-water
55a	Course spent carbon
55b	Spent carbon fines
55c	Hot reactivated carbon
55d	Cool reactivated carbon slurry
56	Activated/reactivated carbon
57′	Loaded/reloaded carbon slurry
57	Loaded/reloaded carbon
57a	Acid-rinsed loaded carbon
57b	Rinsed loaded carbon
57c, 57c′	Dilute acid solution
57d, 57d′	Aqueous rinse solution
57e	Caustic rinse solution
57f	Carrier fluid
60	Holding tank
70	Continuous carbon loading/adsorption process
70′	Continuous carbon loading/adsorption system
100	Process for the continuous recovery of metals
100′	System for the continuous recovery of metals
200	Acid wash tank
200′	Aqueous rinse tank
200″	Caustic rinse tank
220	First chamber
221	First fluidized bed panel
222	First inlet
223a	First recirculation inlet
223b	First recirculation outlet
224	First weir
226	First screen
227	First overflow outlet
228	First discharge outlet
229	First recirculation tank
230	Second chamber
231	Second fluidized bed panel
232	Second inlet
233a	Second recirculation inlet
233b	Second recirculation outlet
234	Second weir
236	Second screen
237	Second overflow outlet
238	Second discharge outlet
239	Second recirculation tank
240	Third chamber
241	Third fluidized bed panel
242	Third inlet
243a	Third recirculation inlet
243b	Third recirculation outlet
244	Third weir
246	Third screen
247	Third overflow outlet
248	Third discharge outlet
249	Third recirculation tank
251	Acid overflow
253	Drained acid return
254	Rinse water overflow
256	Drained rinse water return
257	Caustic rinse overflow
260	Bottom wall
266	Inner tubular wall
268	Outer tubular wall
282	First channel
284	Second channel
286	Third channel
301	Inlet seal
302	Inlet mount
304	Inlet
306	First end
308	Second end
310	One or more sidewalls
312	Effluent port mount
314	Mounting member
316	Effluent port
318	One or more baffles
320	Fluidized bed panel
322	Influent port mount
324	Filter (e.g., disk screen)
326	Influent port
328	Outlet
329	Outlet seal
330	Outlet mount
340	Residence chamber
350	Fluidizing chamber
402	Mount
404	Base
405	First chamber
406	Cell body
407	Second chamber
408	Third chamber
410	Inlet
412	One or more inlet sidewalls
413	One or more openings
414	Inlet mount
417	One or more insulators
420	First outlet
422	One or more first outlet sidewalls
424	First outlet mount
430	Second outlet
432	One or more second outlet sidewalls
434	Second outlet mount
440	First end
441	Fastener
442	Anode terminal
442a	Fastener
442b	Clamp
442c	Terminal lead
442d	Conductive washer
442e	Insulative bushing
442f	Thread or equivalent securing feature
442g	Complimentary thread or securing feature
442h	Conductive support
442i	Receiving portion
444	Anodic panel
445	Cathodic flange
446	Insulative panel
447	Anodic panel
450	Baffle
452	Anodic panel
454	Anode/Cathode insulator
456	Anode/Cathode insulator support
458	One or more receiving portions
460	Residence chamber
462	One or more channels
472	Cathode
473	One or more protuberances
474	Anode
476	One or more insulators
477	Inner anode
479	Outer anode
480	Second end
482	One or more sidewalls
1000	Process for the continuous recovery of metals
1002-1046	Continuous acid wash steps
1048-1080	Continuous elution steps
1082-1100	Continuous electrowinning steps
2000	Acid wash tank
2001	First filter
2002	Skid
2003	Housing
2004	Fastener
2005	Clamp
2006	First filter outlet
2007	First adjustable mount
2008	Recycle screen
2009	Second adjustable mount
2011	Nozzle
2018	Baffle
2020	Chamber
2021	Fluidized bed panel
2022	Inlet
2023	Pump
2023a	Recirculation inlet
2023b	Recirculation outlet
2024	Second filter
2026	First screen
2027	Overflow outlet
2028	Discharge outlet
2029	Recirculation tank
2033b	Recirculation outlet
2036	Second screen
2039	Recirculation tank
2060	Holding tank
2082	First channel
9000	Conventional batch metal recovery process
9000′	Conventional batch metal recovery system
9100	Conventional batch acid wash process
9100′	Conventional batch acid wash system
9120	Acid wash vessel
9132	Pump
9134	Carbon transfer pump
9136	Pump
9140	Dilute acid tank
9150	Sump pump
9160	Neutralizing tank
9200	Conventional batch (Zadra strip) elution process
9200′	Conventional batch (Zadra strip) elution system
9220	Barren solution tank
9232	Carbon transfer pump
9234	Barren solution backup pump
9236	Barren solution pump
9237	Barren solution
9239	Hot barren solution
9240	Strip vessel
9250	Heating skid or equivalent heat exchanger
9300	Carbon regeneration process
9400	Conventional batch electowinning process
9400′	Conventional batch electowinning system
9420	Batch electrolytic metal recovery cell
	(e.g., removable plate cathodes)
9421	Hot electrolyte solution
9430	Pump
9440	Electrowinning pump box
9500	Descaled loaded carbon
9530	Electrolyte solution
9540	Barren solution
9550	Spent carbon
9560	Activated/reactivated carbon
9570	Loaded or reloaded carbon
9700	Conventional batch carbon loading process

Claims

What is claimed is:

1. A system [100′] for the continuous recovery of metals comprising at least one of the following:

a continuous acid wash system [10′] configured for receiving a continuous, uninterrupted inflow of loaded carbonaceous particulate [57] and delivering a continuous, uninterrupted outflow of descaled loaded carbonaceous particulate [50];

a continuous elution system [20′] configured for receiving a continuous, uninterrupted inflow of a strip solution [51] containing a descaled loaded carbonaceous particulate [50] and delivering a continuous, uninterrupted outflow of electrolyte solution [53]; and,

a continuous electrowinning system [40′] configured for receiving a continuous, uninterrupted inflow of electrolyte solution [53], delivering a continuous uninterrupted outflow of a barren solution [54], and continuously and uninterruptedly forming a cathode sludge concentrate [53 f];

wherein each of the continuous acid wash system [10′], the continuous elution system [20′], and the continuous electrowinning system [40′] are configured to operate simultaneously without interruptions common with conventional batch metal recovery processes.

2. The system [100′] according to claim 1, further comprising a carbon regeneration system [30′] operatively connected to said continuous elution system [40′].

3. The system [100′] according to claim 1, further comprising a continuous carbon loading/activation system [70′] operatively connected to said continuous acid wash system [10′].

4. The system [100′] according to claim 1, further comprising a holding tank [60] operatively connected between said continuous acid wash system [10′] and said continuous elution system [20′].

5. The system [100′] according to claim 1, comprising all three of said continuous acid wash system [10′], said continuous elution system [20′], and said continuous electrowinning system [40′].

6. The system [100′] according to claim 1, further comprising one or more pumps [13, 23, 33].

7. The system [100′] according to claim 1, wherein said continuous elution system [20′] is operatively connected to the continuous electrowinning system [40′].

8. The system [100′] according to claim 7, wherein continuous elution system [20′] further comprises one or more screens or filters [324] configured to prevent carbonaceous particulate from passing to the continuous electrowinning system [40′].

9. The system [100′] according to claim 1, wherein the continuous acid wash system [10′] further comprises a chamber [220] adapted for retaining a fluidization medium; an inlet [222] adapted for receiving a feed containing loaded carbonaceous particulate [57]; a fluidized bed distribution panel [220] or other means adapted for fluidizing the loaded carbonaceous particulate [220] in the presence of said fluidization medium; an outlet [228] adapted to pass loaded carbonaceous particulate and fluidization medium from the chamber; and a screen [226] adapted to filter loaded carbonaceous particulate from a fluidization medium;

wherein the continuous elution system [20′] comprises a splash vessel [22], a continuous elution vessel [24], and a flash vessel [25], wherein the splash vessel [22] is operatively connected to the continuous elution vessel [24] in series, the continuous elution vessel [24] is operatively connected to the flash vessel [25] in series, and the splash vessel [22] is operatively connected to the flash vessel [25] in parallel; and,

wherein the continuous electrowinning system [40′] comprises a continuous electrolytic metal recovery cell [42] having a cell body [406] configured to maintain electrolyte solution [53] at a high pressure and/or temperature; at least one anode [474]; at least one cathode [472]; an inlet [410] configured for receiving a continuous, uninterrupted influent stream of electrolyte solution [53]; a first outlet [420] configured for discharging a continuous, uninterrupted effluent stream of barren solution [54]; a second outlet [430] configured for removing cathode sludge concentrate [53 f]; and a residence chamber [460] configured to continuously transfer electrolyte solution [53] from said inlet [410] to said first outlet [420] and increase residence time of said electrolyte solution between said at least one anode [474] and said at least one cathode [472], the residence chamber [460] comprising one or more channels [462] which are configured to provide a forced flow of electrolyte solution [53] therein which is strong enough to continuously dislodge and/or transport cathode sludge concentrate along said one or more channels [462] and eventually out of said residence chamber [460].

10. The system [100′] according to claim 1, wherein said continuous acid wash system [10′] further comprises at least one of a dilute acid solution [57 c], an aqueous rinse solution [57 d], and a caustic rinse solution [57 e]; wherein the continuous elution system [20′] further comprises a solution containing at least one of a carbonaceous particulate loaded with a precious metal, an electrolyte solution, spent carbonaceous particulate, a caustic, an aqueous component, and cyanide; and wherein the continuous electrowinning system [40′] further comprises an electrolyte solution.

11. The system [100′] according to claim 1, wherein the continuous acid wash system [10′], the continuous elution system [20′], and the continuous electrowinning system [40′] are each configured to increase a pressure and/or temperature of a solution or slurry contained therein.

12. The system [100′] according to claim 1, wherein a carbon regeneration system [30′] is operatively connected to said continuous elution system [20′], a continuous carbon loading/activation system [70′] is operatively connected to said continuous acid wash system [10′], and the carbon regeneration system [30′] is operatively connected to said carbon loading/activation system [70′].

13. The system [100′] according to claim 1, wherein said continuous acid wash system [10′] is operatively connected to the continuous elution system [20′].

14. A process [100] for the continuous recovery of a metal comprising:

continuously feeding [1004] a continuous wash system [10′] with particulate [57] loaded with a metal;

continuously washing [1006, 1020, 1034] said loaded particulate [57] within the continuous wash system [10′] to descale the loaded particulate;

continuously removing [1046] descaled loaded particulate [50] from said continuous wash system;

continuously loading [1050] a continuous elution system [20′] with said descaled loaded particulate [50];

continuously removing [1064] electrolyte solution [53] from said continuous elution system [20′];

continuously feeding [1066, 1082, 1084] a continuous electrowinning system [40′] with said electrolyte solution [53];

continuously removing [1070, 1096] barren solution [54] from said continuous electrowinning system [40′]; and,

continuously delivering [1072] said spent electrolyte solution to said continuous elution system [20′];

wherein each of the continuous wash system [10′], the continuous elution system [20′], and the continuous electrowinning system [40′] are operably connected and configured to allow the above steps to be performed simultaneously.

15. The process [100] according to claim 14, further comprising forming said loaded particulate by continuously adsorbing metal onto said particulate in a continuous loading/adsorption system [70′] identical to said continuous wash system [10′].

16. The process [100] according to claim 15, wherein said particulate is one of a carbonaceous particulate, a polymeric adsorbent, or an ion-exchange resin.

17. The process [100] according to claim 14, further comprising continuously removing cathode sludge concentrate [53 f] from the continuous electrowinning system [40′].