AU2016202867A1 - Apparatus and method for thermal extraction of metals - Google Patents

Abstract

An apparatus and methods for removing metal from complex materials. - 18 - u2u zD(D \z LnL- t . iI: 0 =>

Description

APPARATUS AND METHOD FOR THERMAL EXTRACTION OF METALS BACKGROUND OF INVENTION Ore is defined as a mineral or an aggregate of minerals from which a valuable constituent 5 can be extracted; in most cases the extraction is a metal. Ore must be processed to separate unwanted organics and minerals and/or inorganic materials from metal. Once ore is processed, it may be refined to separate different types of metals. For example, Cupellation is a refining method used to separate silver from lead. Complex ores are defined as ores having a low ratio of metal to aggregate organic and inorganic material; that is, in complex ores, metal is difficult to 0 separate from aggregate organic and inorganic material. Known methods for extracting metal from complex ores include exposing lime and/or cyanide to ore slurry, or other similar leaching processes. These methods are inefficient and cost prohibitive. Consequently, unprocessed complex ores may constitute unrealized profit. Known methods of extraction of complex ore are toxic to the environment: toxic gases, chemicals, and 5 polluted water are released into the environment. Printed circuit boards can be found in most electrical or electronic equipment: calculators, remote control units, computers, tablets, mobile phones, etc. Typically printed circuit boards contain 40% metal, 30% organics, and 30% ceramics. The metals contained in printed circuit boards include Gold, Silver, Palladium, and Platinum, amongst others. Although 20 recent Federal and State regulations require printed circuit boards to be recycled, people have been extracting precious metals from printed circuit boards for many years. Known methods to recover precious metals from printed circuit boards closely resemble known methods to extract metal from complex ores, and suffer from the same problems. - 1 - The thermal treatment of complex materials (e.g. complex ores and printed circuit boards) bringing about physical and chemical transformations enabling recovery of metals is known in the art. Such treatment may produce saleable products such as pure metals, or intermediate compounds or alloys that are suitable for further refinement. It is known that 5 plasma environments can provide high temperatures that can refine metal. For example, plasma environments have been used to convert iron slag to pure iron. High temperature, plasma environments can be used to process complex materials enabling recovery of metals. Successful extraction of metal from complex materials in a plasma environment requires a reactor that: (a) can process industrial flow rates; (b) has constant exposure temperatures; (c) 0 has low failure rates and low thermal breakdown of the plasma torch and other reactor components; and (d) has components that are easily accessible for service or maintenance. Described herein is a reactor assembly (10) which provides an extremely high temperature environment to disassociate unwanted material from metals; that is, process complex materials. In one embodiment, the reactor assembly (10) may be part of a complex material 5 processing system (20), which provides additional environmental or processing features. The complex material processing system (20) is generally shown, in Figs. 1 - 2. Although variations of the complex material processing system (20) are shown here for exemplary purposes, it should be noted that the complex material processing system (20) may be embodied in many different forms and should not be construed as limited to the embodiments set 20 forth herein. Referring to Fig. 1, in a first embodiment, the complex material processing system (20) maybe comprised of a reactor assembly (10), a gas treatment system (700), and an off-gas system (800). Complex material enters the complex material processing system at (1) and is -2processed through the reactor assembly (10). In the simplest scenario, processed complex material is removed from the system at (2). As complex material is processed through the reactor assembly (10) it may release gases such as carbon, sulphur, and oxygen, amongst others. As gases leave the reactor assembly (10) 5 at (3), complex material particulates having lower densities may be pulled into the gas treatment system (700). The gas treatment system (700) comprises a plurality of filters to capture complex material particulates. Because some complex material particulates entering the gas treatment system (700) may contain metal, the recovered complex material particulates may be chemically treated (50) to allow full or close to full recovery of all desired metals. In one embodiment the 0 chemical treatment (50) may be an acid or base treatment. Gases continue to move from the gas treatment system (700) to the off-gas system (800). The off-gas system (800) captures and cleans process gases from the reactor assembly (10). Preferably, the off-gas system (800) runs at vacuum or below atmospheric pressure forcing process gases to move from the reactor assembly (10) toward the off-gas system (800). 5 Referring to Fig. 2, in another embodiment, the system further comprises a secondary melt system (900). Metals may be so ensconced in complex materials that they cannot be completely processed in the reactor assembly (10). In this case, complex material may also be processed through a secondary melt system (900). The secondary melt system (900) can be a second reactor assembly (10), inductive coils, resistive heating or other known heat delivery 20 systems, or a combination thereof. Desired metal may still be shrouded in unwanted organic and inorganic material as it leaves the secondary melt system (900) at (7). To remove the remaining unwanted organic and inorganic materials complex material can be exposed to additional chemical treatment (50) at (7). -3- In each of the above described embodiments, and any embodiments which are obvious variations thereof, the components of the system may be operably associated with each other using high temperature ducting or other similar mechanisms. The system, regardless of embodiment, uses an input/output ("I/O") control system known in the art. Preferably, the 1/0 5 control system can, at a minimum, measure flow rates into and out of the reactor assembly (10), through the gas treatment system (700), and the off-gas system (800). Further, the 1/0 control system contemporaneously adjusts run environments so that gases and other toxins are appropriately treated before release into the environment. 0 BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the present invention will become apparent in the following detailed descriptions of the preferred embodiment with reference to the accompanying drawings, of which: Fig. 1 is a flow chart showing the reactor assembly in a complex material processing 5 system; Fig. 2 is a flow chart showing the reactor assembly in a complex material processing system; Fig. 3 is a schematic of the reactor assembly; Fig. 4 is a schematic of the reactor assembly; 20 Fig. 5 is a schematic of the reactor assembly; Fig. 6 is a schematic of the reactor assembly; Fig. 7 is a schematic of the reactor assembly; Fig. 8 is a schematic of the torch isolation valve; -4- Fig. 9 is a schematic of the ore feed system; Fig. 10 is a schematic of the ore feed system; Fig. 11 is a schematic of the fourth-chamber isolation valve; Fig. 12 is schematic of a generic plasma torch; 5 Fig. 13 is a schematic of a generic plasma torch. DETAILED DESCRIPTION OF THE INVENTION The present invention is described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This 0 invention may, however, may be embodied in many different forms and should not be construed as limited to the embodiments set for herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Reactor Assembly 5 Referring to Figs. 3, 4, 9, 12, 13, in one embodiment, the reactor assembly (10) comprises a susceptor (200) and a plasma torch (300). Referring to Figs. 5-13, in another embodiment, the reactor assembly (10) is comprised of a susceptor (200), a plasma torch (300), and a first chamber or feed chamber (100). Preferably, the susceptor (200) is encompassed by the tertiary chamber (500). The tertiary chamber (500) allows particulate and gas exhaust into a gas 20 treatment system (700). The susceptor (200) is defined by an input end (210) and an output end (220). The feed chamber is defined by an input end (110) and an output end (120). The output end (120) of the -5feed chamber (100) operably mates with the input end (210) of the susceptor (200); preferably, using a flange or articulated clamping interface (130). Preferably, the feed chamber (100) is conically shaped having an input end (110) and an output end (120) where the input end (110) has a larger diameter than the output end (120). The 5 input end (110) has a diameter sufficient in size to accept a plasma torch (300) where the plasma torch is of sufficient size to create the necessary temperature to create reaction in complex material. Preferably, the feed chamber (100), susceptor (200), and/or tertiary chamber (500) further comprises a material feed system (550). Optimally, the material feed system (550) is continuous. 0 The material feed system may be comprised of one feed hopper (555) or a plurality of feed hoppers (555), and a screw feeder system (580). The screw feeder system comprises a screw conveyor (556) and feed chamber valve (557). Optimally, the material feed system (550) has at least two feed hoppers (555) so that one feed hopper (555) can be loaded while the other is discharged into the upper chamber (100). 5 To deliver material to the feed chamber (100) oxygen is aspirated from the feed hopper (555). The feed hopper (555) is back filled with a carrier gas. When the feed chamber valve (557) and the s crew conveyor (556) are in the open or on position, feed material and gas are delivered to the susceptor (200) through the feed chamber (100). Preferably, the material feed system (550) delivers feed material and carrier gas along the same axis at which in one 20 embodiment, the at least one feed tube (101) releases material into the susceptor (200). In another embodiment, the at least one feed tube (101) has an extended length so that it delivers material closer to the plasma torch (300). Preferably, the extended feed tube (101) is adjustable -6and angled. The angle is similar to that of the feed chamber (100) wall; the angle and length are dependent upon the type of ore that is being processed. Preferably, the feed chamber (100) and the susceptor (200) are encompassed by the tertiary chamber (500). The tertiary chamber (500) allows particulate and gas exhaust into the 5 gas treatment system (700). Preferably, the tertiary chamber (500) has at least one chamber door (530). The chamber door (530) allows access for maintenance. The tertiary chamber (500) can be tubular in shape and is defined by an input end (510) and an output end (520). Preferably, the output end (520) of the tertiary chamber (500) comprises at least one quench ring (560). The at least one quench ring (560) comprises a plurality of gas nozzles. As 0 processed material falls through the susceptor (200), it passes through the quench rings (560) where it is sprayed by gas. Preferably, the gas nozzles are pointed toward the center of the at least one quench ring (560) and down toward the output end (620) of a fourth chamber (600). Preferably, the quench gas is a noble gas. The fourth chamber (600) is defined by an input end (610) and an output end (620). 5 Preferably, the fourth chamber is conically shaped where the input end (610) has a diameter larger than the output end (620). The output end (520) of the tertiary chamber (500) operably mates with the input end (610) of the fourth chamber. The output end (620) of the fourth chamber (600) comprises a lower isolation valve (540). The lower isolation valve (540) allows the apparatus to maintain a low oxygen environment while allowing processed material to be 20 removed and collected. The susceptor (200) may be surrounded by a secondary heating system (240). Preferably, the susceptor (200) is made of graphite. Although the susceptor (200) can be any shape, preferably it is generally tubular. The length and geometry of susceptor (200) is dependent on -7various factors including, but not limited to, plasma torch (300) size and complex material feed rates. Optimally, the susceptor (200) is surrounded by an insulation blanket (231) and then an insulating liner (235). The insulating liner (235) is then surrounded by the secondary heating system (240). Preferably, the secondary heating system (240) is an inductive heating device (e.g. 5 induction coils) or resistive heating device. The purpose of the secondary heating system (240) is to keep the susceptor (200) temperature relatively constant. If the secondary heating system (240) is an inductive heating device, an electromagnetic field is created which stirs complex material as it passes through the susceptor (200). Graphite is allowed to expand or contract as necessary. 0 The susceptor (200) is defined by an input end (210) and an output end (220). The input end (210) of the susceptor (200) accommodates the plasma torch (300) and material feed system (550). The plasma torch (300) has an active end and an inactive end where the active end is the anode end (refer to Fig. 9). The active end is placed into the susceptor (200). The depth of insertion is variable and is dependent upon factors including but not limited to the size of the 5 torch and susceptor (200). The plasma torch (300) enters the susceptor (200) through a torch isolation valve (320). The torch isolation valve (320) creates a vacuum seal between itself and the susceptor (200) allowing for adjustments to be made on the plasma torch (300), and maintain hot process conditions within the susceptor (200). 20 Preferably, the output end (220) of the susceptor (200) projects through a refractory base plate (233). Preferably, the secondary heating system (240) is supported by the refractory base plate (233); the refractory base plate (233) sits on a water cooled base plate (234). Preferably, the refractory base plate (233) can be replaced or maintained. - 8 - Preferably, the susceptor (200), the graphite insulation blanket (231), and the insulating liner (235) can be replaced or maintained. Preferably, the susceptor (200) is easily released from the reactor (10) for replacement or maintenance. Preferably, susceptor (200) temperature is monitored at least, the input end (210) using a reaction thermocouple (250) and the output end 5 (220) using an exit thermocouple (251); each thermocouple (250, 251) is monitored by the 1/0 control system. Preferably, the thermocouples (250, 251) can be replaced or maintained. Known methods are used to cool each component of the reactor assembly (10). Preferably, reactor assembly (10) components are cooled by circulating water and coolant through a coolant manifold. The manifold is controlled by the 1/0 system mentioned above. 0 Known methods are used to provide electrical power to the reactor assembly (10). Plasma Torch Plasma torches are known in the art. Plasma torches can be classified as low-pressure discharge and atmospheric discharge. Low-pressure discharge torches include, but are not limited to: glow discharge plasmas, capacitively coupled plasma, cascaded arc plasma source, 5 inductively coupled plasma, wave heated plasma. Atmospheric discharge torches include, but are not limited to: arc discharge, corona discharge, dielectric barrier discharge, capacitive discharge. A generic plasma torch is shown in Figs. 12-13. However, any of the above named plasma torches or any other known plasma torch may be used in the reactor assembly (10). 20 Generally, in a generic plasma torch, burn gas enters the torch at a cathode and travels toward an electrical arc, becoming plasma, and exits through an anode throat. The cathode in this instance is positively charged and the anode is negatively charged. The two are electrically isolated from one another. The conductive gas that becomes plasma is introduced at a velocity that stretches -9the plasma arc beyond the anodes throat to thermally react the ore being fed before the arc returns and terminates on the face of the anode. Many different types of burn gases have been used with plasma torches including air, oxygen, nitrogen, hydrogen, argon, CH 4 , C 2

H

4 and C 3

H

6 . Preferably, the plasma torch (300) is of the type where burn gas is fed into the plasma 5 torch (300) tangent to the anode and electrode. Preferably, the plasma torch polarity is set to run in non-transfer mode. A transfer plasma torch the arc is looped from the torch's anode to a "work piece" that has a negative polarity. The size of the arc is limited in size by the distance between the anode and the "work piece". A non-transfer plasma torch has both negative and positive polarity. In the reactor assembly (10) the arc is looped from the electrode to the torch 0 nozzle and does not have a size limitation consequently, complex materials can be continuously processed through the reactor assembly (10). Referring to Fig. 13, the plasma torch (300) is comprised of at least: an electrode (310), gas ring (320), insulator ring assembly (330), and nozzle (340). Preferably, the plasma torch (300) is a direct current plasma torch. In a direct current plasma torch, the electric arc is formed 5 between the nozzle (340) and the electrode (310). Continuous input of carrier/working gas through the gas ring (320) creates thermal plasma. The insulator ring assembly (330) protects the gas ring (320) from thermal plasma. Preferably, maintenance on the plasma torch (300) can be performed by sealing the torch isolation valve (540), and lifting the plasma torch (300) out of the reactor assembly (10). Preferably, the electrode (310), gas ring (320), insulator ring 20 assembly (330), and nozzle (340) can be replaced or maintained. Post Reactor Assembly Processing! Preferably, particulates from the reactor assembly (10) enter the gas treatment system (700). The gas treatment system (700) is attached to the tertiary chamber (500). There exists a -10negative pressure that allows particulate matter to flow from the reactor (10) to the gas treatment system (700). The gas treatment system (700) comprises at least one filter that can filter out ore particulates before gases enter the off-gas system (800). Preferably, the off-gas system (800) runs at a vacuum or below atmospheric pressure. 5 This causes gases to flow from the gas treatment system (700) to the off-gas system (800). The off-gas system (800) uses known methods to filter sulphur and other harmful gases that are received from the processed ore before release of neutral gases into the atmosphere. In some cases, even after processing, complex material through the reactor assembly (10), valuable metal may remain difficult to extract. In this case, the ore is processed through a 0 Secondary Melt System (900). This system can be an inductive heat system or a smelter, for example. Operations Preferably, the feed material is delivered into the susceptor (200) as a fine mesh size and has a moisture level between 0 - 20%. Complex material that has higher moisture content may 5 clump. Clumped material is heavier and falls through the susceptor (200) too quickly and, consequently, complex material hang time is decreased. High moisture content also causes consumables, such as the torch head, to burn out more quickly. The susceptor (200) is prepared for processing complex material by removing oxygen from the susceptor (200). This is done by using a vacuum pumping system. In a preferred 20 embodiment, once the pressure in the susceptor (200) reaches close to 0 psia, the susceptor (200) is backfilled with burn gas. Preferably, the susceptor (200) is maintained at approximately 0-2 psia. Preferably, the susceptor (200) is maintained at about 3000 'F where the plasma torch runs - 11 at approximately 25,000 'F. These parameters may vary depending on susceptor (200) size, type of complex material, and feed rate. In this specification, the terms "comprise", "comprises", "comprising" or similar terms are intended to mean a non-exclusive inclusion, such that a system, method or apparatus that 5 comprises a list of elements does not include those elements solely, but may well include other elements not listed. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia. -12-

Claims (19)

1. An apparatus for processing complex material comprising: a chamber having a first opening for accommodating entry of a plasma torch where said plasma torch operates in a non-transfer mode; where said torch has an active end and an inactive end; where said torch is operatively located through the first opening in an orientation with the active end extending into the chamber and away from the first opening and the inactive end is secured in the chamber proximate to the first opening; where said chamber further comprises a second opening near the first opening for entry of complex material and carrier gas having a constrained path into the chamber, the second opening being proximate to the first opening; the path of the complex material and carrier gas being along the same axis in relation to the major axis of the plasma torch; where said chamber is surrounded by a secondary heating system where the apparatus consists of components that are subject to wear or include consumable components.

2. The apparatus of claim 1 where the apparatus comprises a, secondary melt system, gas treatment system, off-gas system, or combinations thereof.

3. The apparatus of claim 1 where the chamber is replaced with a second chamber.

4. The apparatus of claim 1 where at least a first graphite insulation blanket is replaced with a second graphite insulation blanket, and/or a first refractory lining is replaced by a second refractory lining.

5. The apparatus of claim 1 where at least a first electrode is replaced by a second electrode, a first gas ring is replaced by a second gas ring, a first insulator ring is replace by a second insulator ring, and/ or a first nozzle is replaced by a second nozzle. 13

6. A method to replace components that are subject to wear or include consumable components, where said apparatus comprises: a chamber having a first opening for accommodating entry of a plasma torch where said plasma torch operates in a non-transfer mode; where said torch has an active end and an inactive end; where said torch is operatively located through the first opening in an orientation with the active end extending into the chamber and away from the first opening and the inactive end is secured in the chamber proximate to the first opening; where said chamber further comprises a second opening near the first opening for entry of complex material and carrier gas having a constrained path into the chamber, the second opening being proximate to the first opening; the path of the complex material and carrier gas being along the same axis in relation to the major axis of the plasma torch; where said chamber is surrounded by a secondary heating system; where the chamber is a component subject to wear or is a consumable part; where the chamber is insulated by, at least, a graphic insulation blanket or refectory lining; where the graphite insulation blanket and the refractory lining is subject to wear and is a consumable part; where the torch comprises at least an electrode, a gas ring, insulator ring, or nozzle that is subject to wear or is a consumable part; where the method comprises: replacing a first chamber with a second chamber; replacing, at least, a first graphite insulation blanket is with a second graphite insulation blanket, and/or a first refractory lining is by a second refractory lining; or replacing, at least, a first electrode is by a second electrode, a first gas ring by a second gas ring, a first insulator ring by a second insulator ring, and/ or a first nozzle by a second nozzle.

7. An apparatus for processing complex material comprising: 14 a chamber having a first opening for accommodating entry of a plasma torch where said plasma torch operates in a non-transfer mode; where said torch has an active end and an inactive end; where said torch is operatively located through the first opening in an orientation with the active end extending into the chamber and away from the first opening and the inactive end is secured in the chamber proximate to the first opening; where said chamber further comprises a second opening near the first opening for entry of complex material and carrier gas having a constrained path into the chamber, the second opening being proximate to the first opening; the path of the complex material and carrier gas being along the same axis in relation to the major axis of the plasma torch.

8. The apparatus of claim 7 where the apparatus comprises a, secondary melt system, gas treatment system, off-gas system, or combinations thereof.

9. The apparatus of claim 7 where the chamber is replaced with a second chamber.

10. The apparatus of claim 7 where the at least one thermocouple is replaced by a second thermocouple.

11. The apparatus of claim 7 where the chamber is insulated by, at least, a graphic insulation blanket or refectory lining; where the graphite insulation blanket and the refractory lining is subject to wear and is a consumable part.

12. The apparatus of claim 11 where at least a first graphite insulation blanket is replaced with a second graphite insulation blanket, and/or a first refractory lining is replaced by a second refractory lining.

13. The apparatus of claim 7 where the torch comprises at least an electrode, a gas ring, insulator ring, or nozzle that is subject to wear or is a consumable part. 15

14. The apparatus of claim 13 where at least a first electrode is replaced by a second electrode, a first gas ring is replaced by a second gas ring, a first insulator ring is replace by a second insulator ring, and/ or a first nozzle is replace by a second nozzle.

15. A method to replace components that are subject to wear or include consumable components, where said apparatus comprises: a chamber having a first opening for accommodating entry of a plasma torch where said plasma torch operates in a non-transfer mode; where said torch has an active end and an inactive end; where said torch is operatively located through the first opening in an orientation with the active end extending into the chamber and away from the first opening and the inactive end is secured in the chamber proximate to the first opening; where said chamber further comprises a second opening near the first opening for entry of complex material and carrier gas having a constrained path into the chamber, the second opening being proximate to the first opening; the path of the complex material and carrier gas being along the same axis in relation to the major axis of the plasma torch; where the chamber is a component subject to wear or is a consumable part; where the chamber is insulated by, at least, a graphic insulation blanket or refectory lining; where the graphite insulation blanket and the refractory lining is subject to wear and is a consumable part; where the torch comprises at least an electrode, a gas ring, insulator ring, or nozzle that is subject to wear or is a consumable part; where the method comprises: replacing a first chamber with a second chamber; replacing, at least, a first graphite insulation blanket is with a second graphite insulation blanket, and/or a first refractory lining is by a second refractory lining; or replacing, at least, a first electrode is by a second electrode, a first gas ring by a second gas ring, a first insulator ring by a second insulator ring, and/ or a first nozzle by a second nozzle. 16

16. An apparatus for processing complex material comprising: a chamber having a first opening for accommodating entry of a plasma torch; where the chamber is graphite; where said torch has an active end and an inactive end; where said torch is operatively located through the first opening in an orientation with the active end extending into the chamber and away from the first opening and the inactive end is secured in the chamber proximate to the first opening; where said chamber further comprises a second opening for entry of complex material into the chamber.

17. The apparatus of claim 16 where the plasma torch creates inductively coupled plasma, wave heat plasma, arc discharge plasma, or AC/DC plasma in transfer or non transfer mode.

18. The apparatus of claim 16 where the chamber is surrounded by a secondary heating system.

19. The apparatus of claim 16 comprises a secondary melt system, gas treatment system, off-gas system, or combinations thereof. 17