Method for recovering and extracting gold from electronic waste or gold-containing minerals, ores and sands
阅读说明：本技术 用于从电子废弃物或含金矿物、矿石和沙子中回收和提取金的方法 (Method for recovering and extracting gold from electronic waste or gold-containing minerals, ores and sands ) 是由 I·卢博米尔斯基 V·卡普兰 N·多斯姆克哈米多夫 E·佐尔达斯贝 于 2018-11-01 设计创作，主要内容包括：描述一种用于从含金材料,例如电子废料、矿物和沙子中回收金的方法。所述方法包括压碎所述含金材料以获得粒状材料。然后将所述粒状材料在预热区中的含氧气体环境中预热。所述方法还包括将氧化的粒状材料与含氯材料混合并在反应区中处理混合物。通过加热混合物以使所述含氯材料热分解并产生含氯气体混合物,并且通过对所述含氯气体混合物施加电磁场以使氯离子化来进行所述处理。然后将由于金和氯离子之间的化学反应在所述反应区中产生的挥发性含金氯化物产物冷却以将所述挥发性含金氯化物产物转化成固相含金材料。(A method for recovering gold from gold-bearing materials, such as electronic scrap, minerals and sand, is described. The method comprises crushing the gold-bearing material to obtain a granular material. The particulate material is then preheated in an oxygen-containing gas environment in a preheating zone. The method also includes mixing the oxidized particulate material with a chlorine-containing material and treating the mixture in a reaction zone. The treatment is performed by heating a mixture to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture, and by applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine. The volatile gold-containing chloride product generated in the reaction zone as a result of the chemical reaction between gold and chloride ions is then cooled to convert the volatile gold-containing chloride product into a solid phase gold-containing material.)
1. A method of recovering gold from a gold-bearing material, the method comprising:
crushing the gold-containing material to obtain a gold-containing particulate material comprising particles having a predetermined particle size;
optionally sublimating other metals from the material;
preheating the gold-bearing particulate material in an oxygen-containing gas environment in a preheating zone to oxidize the gold-bearing particulate material;
mixing the oxidized gold-containing particulate material with a chlorine-containing material;
treating the mixture of oxidized gold-containing particulate material and chlorine-containing material in a reaction zone by: (i) heating the mixture to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture, (ii) applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine, thereby causing a chemical reaction between gold and chlorine ions, and providing a volatile gold-containing chloride product at the reaction zone; and
cooling the volatile gold-containing chloride product to convert the volatile gold-containing chloride product to a solid phase gold-containing material.
2. The method of claim 1, wherein the gold-containing material is selected from the group consisting of old gold-containing printed circuit boards, gold-containing parts of electronic devices, discarded gold-containing electrical connectors, and gold-containing minerals, ores, and sand.
3. The method of claim 1, wherein the predetermined particle size of the gold-containing particulate material is in a range of 0.07mm to 40 mm.
4. A method according to any one of claims 1 to 3, wherein the step of sublimating the other metal is carried out at a temperature between 500 and 900 degrees celsius.
5. The method of claim 4, wherein the other metal comprises arsenic, antimony, or a combination thereof.
6. A method according to any one of claims 1 to 5, wherein the amount of the chlorine-containing material in the mixture is in the range of 1 gram to 1 kg per kg of the gold-containing material.
7. The method of any one of claims 1 to 6, wherein the chlorine-containing material is a particulate material selected from the group consisting of potassium hypochlorite, sodium hypochlorite, calcium hypochlorite, magnesium hypochlorite, barium hypochlorite, potassium chloride-potassium hypochlorite, sodium chloride-sodium hypochlorite, calcium chloride-calcium hypochlorite, magnesium chloride-calcium hypochlorite, barium chloride-calcium hypochlorite, potassium chloride, sodium chloride, ammonium chloride, calcium chloride, magnesium chloride, barium chloride, aluminum chloride, nanosilica, and any combination thereof.
8. The method of claim 1, wherein the chlorine-containing material is a combination of calcium hypochlorite, calcium chloride, and nanosilica.
9. The method of claim 1, wherein the chlorine-containing material is a composition of calcium hypochlorite and nanosilica.
10. The method of claim 9, wherein the calcium hypochlorite is mixed with nano-silica in solid or liquid form to better decompose the calcium hypochlorite to produce the chlorine-containing gas mixture.
11. The method of any one of claims 7 to 10, wherein the nanosilica has a particle size of less than 200 nm.
12. The method of claim 8, wherein the amount of calcium hypochlorite in the composition of calcium hypochlorite and calcium chloride is in the range of 5 to 99 weight percent.
13. The method according to any one of claims 1 to 12, wherein the preheating of the gold-containing particulate material is performed at a temperature in the range of 150 to 750 degrees celsius.
14. A method according to any one of claims 1 to 13, wherein the preheating of the gold-containing particulate material is carried out for a period of time in the range of 5min to 60 min.
15. The process of any one of claims 1 to 14, wherein the oxygen content in the oxygen-containing gas environment in the preheating zone is in the range of 20 to 98 vol%.
16. The method of any one of claims 1 to 15, wherein the heating the mixture to thermally decompose the chlorine-containing material and generate a chlorine-containing gas mixture is performed at a temperature in a range of 150 degrees celsius to 400 degrees celsius.
17. The method of any one of claims 1 to 16, wherein the heating the mixture to thermally decompose the chlorine-containing material and generate the chlorine-containing gas mixture is performed for a time period in a range of 5min to 120 min.
18. The method of any one of claims 1-17, further comprising passing a chlorine-containing gas from an external source through the reaction zone during application of the electromagnetic field.
19. The method of claim 18, wherein the amount of the chlorine-containing gas from the external source passing through the reaction zone is in the range of 5 liters to 400 liters of chlorine per ton of the gold-containing material.
20. The method of any one of claims 1 to 19, wherein the frequency of the electromagnetic field in the reaction zone is in the range of 50kHz-12 GHz.
21. The method of claim 1, wherein the irradiance of the electromagnetic field in the reaction zone is at 0.1kW/cm2To 10kW/cm2Within the range of (1).
22. The method of claim 1, wherein the applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine is performed for a time period in a range of 5min to 180 min.
23. The method of any one of claims 1 to 22, wherein the heating of the mixture of the oxidized gold-containing particulate material and the chlorine-containing material in the reaction zone is performed simultaneously with the applying of the electromagnetic field to the chlorine-containing gas mixture.
24. The method as claimed in any one of claims 1 to 23 wherein the gold-bearing material comprises arsenic and antimony as other metals and is mixed with coal and reduced at a temperature of 500-900 ℃.
25. The method of claim 24 wherein the coal consumption is 130-170% of the stoichiometric amount of coal required to fully reduce the arsenic and antimony oxides with carbon.
Technical Field
The present invention relates generally to metallurgical technology for the separation and recovery of precious and rare metals, and in particular to a method for the recovery of gold from gold-bearing materials, such as industrial wastes, minerals, ores and sand.
Background
With the advancement of technology, the demand for electrical and electronic devices has sharply increased. Significant innovations in electrical and electronic technology have shortened the service life of electrical and electronic equipment and, therefore, increased the generation of electronic waste (electronic waste/e-waste). The production of global electronic waste is rapidly increasing and is expected to further accelerate in the near future. This results in the production of a large amount of electronic waste that needs to be disposed of [ a.khaliq, m.a.rhamdhani, g.brooks, s.mass; metal extraction process for electronic waste and existing industrial approaches: overview and Australian observations (Metal extraction Processes for Electronic waters and Existing Industrial Routes: A Review and Industrial personnel availability); resources (Resources), 2014, 3 rd edition, page 152 and 179.
Due to environmental pollution and global regulations, electronic waste disposal including combustion in incinerators, disposal in landfills or export to foreign countries is no longer permitted. Furthermore, the presence of Precious Metals (PM) makes the recovery of electronic waste economically attractive. For example, gold (Au) is used for electronic devices because of its excellent corrosion resistance and high conductivity. It is well known that mobile phones and personal computers are manufactured to consume 3% of the gold mined globally each year. In fact, the gold content in electronic waste and scrap is much higher (10 to 1 kg gold per ton of electronic waste and 0.5 to 13.5 g gold per ton of natural gold ore) compared to natural gold ore, which creates an economic incentive for the recovery of electronic waste.
Existing pyrometallurgical processes for recovering Au from electronic waste are energy intensive, while hydrometallurgical processes using chemical lixiviants, such as aqua regia (i.e., a mixture of concentrated nitric and hydrochloric acids), involve contamination and are therefore environmentally unsustainable. In addition, in some cases, the extraction of primary gold from minerals, ores and sand using existing pyrometallurgical and hydrometallurgical processes can be difficult, environmentally unfriendly or economically unattractive.
For example, U.S. patent No. 4,353,740 describes a process for treating particulate gold-containing ore to recover gold therein. The process includes roasting the ore to remove sulphides, such as sulphur dioxide, then chlorinating the ore in the presence of iron at a temperature of about 350 ℃ to form a mixture of volatile gold chlorides and volatile gold iron chlorides in the chlorine off-gas, then condensing the gold compounds by passing the mixture through a salt, such as sodium chloride, to form a salt melt and separating the gold from the melt.
Us patent No. 5,074,910 describes a process for the recovery of precious metals from sulphide ores. It involves chlorinating a mixture of concentrate and salt to form a liquid melt. The salt preferably contains potassium chloride. The chlorination is carried out at a temperature between 300 and 600 degrees celsius while stirring. The process converts the noble metals in elemental and sulfidic form to noble metal chlorides, which are then recovered by subsequent process steps.
Us patent No. 5,169,503 describes a process for extracting valuable metals from ores. The method comprises the following steps: (a) dissolving value metals from ore by treating the ore with a lixiviant comprising an aqueous solution of a chloride salt, hypochlorite and cyanuric acid; (b) recovering the metal values from the lixiviant.
U.S. patent No. 5,484,470 describes a process for dissolving metallic gold in a ligand and oxidant leaching system in which the solubility of gold is enhanced by the addition of heterocyclic aromatic compounds containing nitrogen or sulfur in the ring.
U.S. patent No. 7,645,320 describes a process for extracting noble metals from a noble metal-containing source, comprising the steps of: (i) contacting a noble metal-containing source with a gaseous chlorine salt; (ii) (ii) condensing the volatile noble metal-containing product of step (i); and (iii) recovering the precious metal from the condensed product of step (ii).
Disclosure of Invention
Despite the existing state of the art in the field of gold recovery and extraction, there is a need in the art for further improvements in the technology for recovering electronic waste to recover gold, and further improvements in the technology for extracting native gold from gold-bearing materials, such as minerals, ores and sand.
It would also be advantageous to have a method for recovering and extracting gold with a low environmental impact agent that can selectively and efficiently extract gold under mild conditions.
In addition, it would be advantageous to have a method for recovering gold from electronic waste that is easily industrialized and has a high yield of recovered metal. In addition, there are many cases where primary Au needs to be extracted from minerals, ores and sands to recover gold, which is easy to industrialize and the yield of extracted metals is high.
The present disclosure meets the foregoing needs by providing a method for recovering gold from electronic waste and extracting gold from minerals, ores and sand. The method comprises crushing gold-bearing material, such as electronic waste, or gold-bearing minerals, ores and sand to obtain a granular material. The granular material includes particles having a predetermined particle size. For example, the predetermined particle size of the granular material may be in the range of 0.07mm to 40 mm.
In one embodiment, the present invention provides a method for recovering gold from a gold-containing material, the method comprising:
crushing the gold-containing material to obtain a gold-containing particulate material comprising particles having a predetermined particle size;
optionally sublimating other metals from the material;
preheating the gold-bearing particulate material in an oxygen-containing gas environment in a preheating zone to oxidize the gold-bearing particulate material;
mixing the oxidized gold-containing particulate material with a chlorine-containing material;
treating the mixture of oxidized gold-containing particulate material and chlorine-containing material in a reaction zone by: (i) heating the mixture to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture, (ii) applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine, thereby causing a chemical reaction between gold and chlorine ions, and providing a volatile gold-containing chloride product at the reaction zone; and
cooling the volatile gold-containing chloride product to convert the volatile gold-containing chloride product to a solid phase gold-containing material.
The method also includes preheating the granular material. The preheating is carried out in an oxygen-containing gas environment in a preheating zone to oxidize the particulate material. The preheating of the granular material may be performed, for example, at a temperature in the range of 150 degrees celsius to 750 degrees celsius for a time period in the range of 5min to 60 min. The oxygen content in the oxygen-containing gas environment in the preheating zone is in the range of 20% to 98% by volume.
The oxidized particulate material is then mixed with a chlorine-containing material. The amount of the chlorine-containing material in the mixture may for example be in the range of 1 gram to 1 kg per kg of the gold-containing material, e.g. electronic waste or gold-containing minerals, ores and sand. Examples of materials suitable for use in the present invention include, but are not limited to, potassium hypochlorite, sodium hypochlorite, calcium hypochlorite, magnesium hypochlorite, barium hypochlorite, potassium chloride-potassium hypochlorite, sodium chloride-sodium hypochlorite, calcium chloride-calcium hypochlorite, magnesium chloride-calcium hypochlorite, barium chloride-calcium hypochlorite, potassium chloride, sodium chloride, ammonium chloride, calcium chloride, magnesium chloride, barium chloride, aluminum chloride, nanosilica, and any combination thereof. The method further comprises treating the mixture of oxidized particulate material with a chlorine-containing material in a reaction zone. The treatment is carried out by heating the mixture and applying an electromagnetic field.
Heating the oxidized granular material and chlorine-containing material mixture is conducted to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture. Heating the mixture to generate the chlorine containing gas mixture may be performed, for example, at a temperature in the range of 150 degrees celsius to 400 degrees celsius for a time period in the range of 5min to 120 min.
Electromagnetic radiation is applied to the chlorine-containing gas mixture to ionize the chlorine, thereby causing a chemical reaction between the gold and the chlorine ions and providing a volatile gold-containing chloride product in the reaction zone. The ionization of chlorine gas can be achieved, for example, by applying an alternating electromagnetic field to the reaction zone at a frequency in the range of 50kHz to 12 GHz. The irradiance of the electromagnetic field in the reaction zone may be, for example, at 0.1kW/cm2To 10kW/cm2Within the range of (1). For example, the electromagnetic field may be applied to the chlorine-containing gas mixture for a time period in the range of 5min to 180min to ionize chlorine.
According to an embodiment of the invention, the heating of the mixture of oxidized particulate material and chlorine-containing material in the reaction zone is performed while applying the electromagnetic field to the chlorine-containing gas mixture.
According to an embodiment of the invention, the method further comprises passing a chlorine containing gas from an external source through the reaction zone during said applying of the electromagnetic field. The amount of the chlorine-containing gas from the external source passing through the reaction zone may for example be in the range of 5 to 400 litres of chlorine per tonne of the gold-containing material, such as electronic scrap, minerals, ores and sand.
The method then comprises cooling the volatile gold-containing chloride product to convert the volatile gold-containing chloride product to a solid phase gold-containing material.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. Additional details and advantages of the invention will be set forth in the detailed description.
Drawings
For a better understanding of the subject matter disclosed herein and to illustrate how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram of a method for recovering gold from gold-bearing materials, such as electronic scrap, minerals, ores, and sand, in accordance with an embodiment of the present invention.
FIG. 2 illustrates a schematic partial longitudinal cross-sectional view of an apparatus for treating a mixture of oxidized particulate material and chlorine-containing material, according to an embodiment of the invention.
Detailed Description
The principles and operation of an apparatus for recovering gold from gold-bearing materials, such as electronic waste, and/or extracting gold from minerals, ores and sand according to the present invention may be better understood with reference to the drawings and the accompanying description. It is to be understood that these drawings are given solely for the purposes of illustration and are not meant to be limiting.
In one embodiment, the present invention provides a method for recovering gold from a gold-containing material, the method comprising:
crushing the gold-containing material to obtain a gold-containing particulate material comprising particles having a predetermined particle size;
optionally sublimating other metals from the material;
preheating the gold-bearing particulate material in an oxygen-containing gas environment in a preheating zone to oxidize the gold-bearing particulate material;
mixing the oxidized gold-containing particulate material with a chlorine-containing material;
treating the mixture of oxidized gold-containing particulate material and chlorine-containing material in a reaction zone by: (i) heating the mixture to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture, (ii) applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine, thereby causing a chemical reaction between gold and chlorine ions, and providing a volatile gold-containing chloride product at the reaction zone; and
cooling the volatile gold-containing chloride product to convert the volatile gold-containing chloride product to a solid phase gold-containing material.
In one embodiment, the invention relates to a method for recovering gold from a gold-containing material, wherein the gold-containing material comprises gold, arsenic, antimony or a combination thereof, the method comprising:
crushing the gold-containing material to obtain a gold-containing particulate material comprising particles having a predetermined particle size;
mixing the gold-containing particulate material with coal;
heating and reducing said mixture of gold-bearing particulate material and coal at a temperature of 500 ℃ -;
preheating the reduced gold-bearing particulate material in an oxygen-containing gas environment in a preheating zone to oxidize the gold-bearing particulate material;
mixing the oxidized gold-containing particulate material with a chlorine-containing material;
treating the mixture of oxidized gold-containing particulate material and chlorine-containing material in a reaction zone by: (i) heating the mixture to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture, (ii) applying an electromagnetic field to the chlorine-containing gas mixture to ionize chlorine, thereby causing a chemical reaction between gold and chlorine ions, and providing a volatile gold-containing chloride product at the reaction zone; and
cooling the volatile gold-containing chloride product to convert the volatile gold-containing chloride product to a solid phase gold-containing material.
In another embodiment, the gold-containing material is selected from the group consisting of old gold-containing printed circuit boards, gold-containing parts of electronic devices, discarded gold-containing electrical connectors, and gold-containing minerals, ores and sand.
In another embodiment, the predetermined particle size of the gold-containing particulate material is in the range of 0.07mm to 40 mm.
In another embodiment, if the gold-bearing material contains arsenic, antimony or a combination thereof in a concentration higher than 0.1 wt.%, a sublimation step is required to remove these metals. In another embodiment, the sublimation step is performed at a temperature between 500 and 900 degrees celsius. In another embodiment, the sublimation step is at 500 to 700 degrees celsius; 650 to 750 degrees centigrade; 600 to 800 degrees centigrade; or between 700 and 900 degrees celsius. In another embodiment, a gold-bearing material comprising gold, arsenic, antimony or a combination thereof is mixed with coal and heated to a temperature between 500-; 650 to 750 degrees centigrade; 600 to 800 degrees centigrade; or between 700 and 900 degrees celsius.
In another embodiment, the coal consumption is 130-170% of the stoichiometric amount of coal required to fully reduce the arsenic and antimony oxides with carbon.
In the present description and claims, the expression "gold-containing material" or "gold-containing materials" is used broadly, alone or in combination, for any gold-containing material, such as minerals, ores and sand, as well as electronic waste.
In the present description and claims, the expression "electronic scrap" is used widely, alone or in combination, for electrical or electronic equipment, including gold-containing parts, subassemblies and consumables, which have been discarded by their users. Examples of electronic waste include, but are not limited to, gold-containing printed circuit boards, gold-containing parts of electronic devices, gold-containing electrical connectors, and the like.
It should be understood that electronic waste (electronic waste/e-waste) can be made up of a large variety of sizes, shapes, and chemicals. For example, printed circuit boards that can be found in electrical and electronic devices are composed of 40% metal, 30% polymer, and 30% ceramic. However, the method of the present invention is not sensitive to the presence of metals other than gold as well as to the presence of other materials.
Referring to fig. 1, a schematic diagram of a method for recovering gold from gold-bearing materials, such as electronic scrap, minerals, ores, or sand, is shown, according to an embodiment of the invention. An initial step of crushing the gold-containing material is performed. During said crushing, the gold-containing material is converted into particles having an average particle size that may be in the range of, for example, 0.07mm to 40 mm. According to the invention, this stage makes it possible to prepare a product which is, on the one hand, more homogeneous and, on the other hand, more processable in the subsequent process steps.
Electronic waste or minerals, ores and sands may contain materials such as polymers, resins, fibers, cellulose paper, sulfur and other combustible materials that can burn and decompose in subsequent processing steps, providing impurities in the final product. Thus, the method comprises preheating the particulate material in an oxygen-containing gas environment to oxidise the particulate material. The preheating of the granular material is carried out in a furnace that provides a preheating zone that has a sufficiently high temperature and is for a desired time to cause oxidation of the granular material. For example, the temperature may be in a range of 150 degrees celsius to 750 degrees celsius. The preheating of the granular material may be carried out for a period of time in the range of 5min to 60min, for example. The oxygen content in the preheating zone may for example be in the range of 20 to 98 vol%.
The method also includes mixing the oxidized particulate material with a chlorine-containing material. The chlorine-containing material may be, for example, in granular form. The amount of chlorine-containing material in the mixture depends on the amount of electronic waste or minerals, ore and sand and/or the size of the reactor. For example, the amount of chlorine-containing material in the mixture may be in the range of 1 gram to 1 kilogram per kilogram of electronic waste or minerals, ores and sand. In another embodiment, the chlorine-containing material in the mixture is in the range of 1 gram to 0.5 kilogram per kilogram of gold-containing material. In another embodiment, the chlorine-containing material in the mixture is in the range of 200g to 700g per kg of gold-containing material.
Examples of chlorine-containing materials suitable for use in the present invention include, but are not limited to, potassium hypochlorite, sodium hypochlorite, calcium hypochlorite, magnesium hypochlorite, barium hypochlorite, potassium chloride-potassium hypochlorite, sodium chloride-sodium hypochlorite, calcium chloride-calcium hypochlorite, magnesium chloride-calcium hypochlorite, barium chloride-calcium hypochlorite, potassium chloride, sodium chloride, ammonium chloride, calcium chloride, magnesium chloride, barium chloride, aluminum chloride, nanosilica, and any combination thereof.
When a combination of two or more different chlorine-containing materials is used, the concentration of the components in the composition may vary over a wide range. For example, when the chlorine-containing material is a composition of calcium hypochlorite and calcium chloride, the amount of calcium hypochlorite in the composition of calcium hypochlorite and calcium chloride can be in the range of 5 wt.% to 99 wt.%. In another embodiment, the amount of calcium hypochlorite in the composition is between 10 to 20 wt.%, 20 to 50 wt.%, 30 to 60 wt.%, or 50 to 100 wt.%.
Another example of a chlorine-containing material may have a composition of calcium hypochlorite, calcium chloride, and nanosilica. Yet another example of a chlorine-containing material may have a composition of calcium hypochlorite and nano-silica, wherein the calcium hypochlorite is mixed with nano-silica in solid or liquid form to better decompose the calcium hypochlorite to produce a chlorine-containing gas mixture, wherein the nano-silica has a particle size between 10-1000 nm. In other embodiments, the nanosilica has a particle size of less than 200 nm.
The method further includes treating the mixture of oxidized particulate material and chlorine-containing material in a reaction zone by heating the mixture to thermally decompose the chlorine-containing material and thereby produce a chlorine-containing gas mixture, and also applying an electromagnetic field to the produced chlorine-containing gas mixture to form a chlorine plasma.
FIG. 2 illustrates a schematic partial longitudinal cross-sectional view of an apparatus for treating a mixture of oxidized particulate material and chlorine-containing material by heating the mixture and applying an electromagnetic field, according to an embodiment of the present invention. It should be noted that for the sake of clarity, the drawings are not to scale, nor are they to scale. It should also be noted that the blocks and other elements in this figure are intended as functional entities only, such that the functional relationships between the entities are shown rather than any physical connections and/or physical relationships. Examples of the construction, materials, dimensions and manufacturing processes of selected elements are provided. Those skilled in the art will appreciate that many of the examples provided have suitable alternatives that may be utilized.
According to an embodiment of the present invention, an apparatus 20 for treating a mixture 25 of oxidized particulate material and chlorine-containing material includes a housing 21 having a housing wall 210. The term "housing" is used broadly to describe any tank, chamber, tube, cassette, enclosure housing, frame assembly or any other structure that may be used to perform a process for recovering or extracting gold from electronic waste or minerals, ore and sand, respectively, in accordance with the teachings of the present invention.
The housing wall 210 defines a reactor 22 having a reaction zone in which the mixture 25 is heated and subjected to an electromagnetic field. It should be understood that the housing 21 may have any desired size and shape, such as cylindrical, prismatic, etc. Further, the size of the cavities may have any desired size distribution.
The inner surface of the housing wall 210 can be made of any suitable material. Examples of such materials include, but are not limited to, ceramic materials containing at least one element selected from silica-based, alumina-based, magnesia-based, or zirconia-based ceramic materials, and any combination thereof.
The mixture of oxidized particulate material and chlorine-containing material may be fed to reactor 22 in various suitable ways. For example, it can be provided by a feed opening 23 provided in the housing wall 210. For this purpose, a feed hopper 24 may be provided, for example at the feed opening 23. Although the feed port 23 is shown at the top of the housing 21 in fig. 2, it may generally be located at any suitable location.
According to some embodiments, the reactor 22 comprises a heater 221 configured to heat and maintain the mixture of oxidized particulate material and chlorine-containing material at a predetermined temperature. The temperature and duration of heating are selected to thermally decompose the chlorine-containing material and produce a chlorine-containing gas mixture. For example, the predetermined temperature may be in the range of about 150 ℃ to about 400 ℃. Heating the mixture to thermally decompose the chlorine-containing material to produce the chlorine-containing gas mixture may be performed for a period of time in the range of 5min to 120 min.
According to some embodiments, the reactor 22 may further include a temperature sensor 222 disposed in the reactor 22 within the mixture 25 and configured to measure a predetermined temperature to control operation of the heater 221.
A method of recovering gold from gold-bearing materials, such as electronic scrap, minerals, ores, and sand, includes applying an electromagnetic field to a chlorine-containing gas mixture in a reaction zone to ionize chlorine.
The formation of gold chlorides is a kinetically limited process. It is known that chlorination is faster than chlorination with chlorine molecules when chlorine is present as a reactive free radical (e.g., in aqua regia). Thus, contacting gold with a chlorine plasma (ions and radicals of chlorine rather than molecules of chlorine) may also accelerate the chlorination process.
The advantage of plasma chlorination over molecular chlorination of chlorine is that it can be achieved at much lower temperatures than those required for thermally driven chlorination, whereas low temperature chlorination processes can be more selective for the production of pure gold chlorides for recovery of gold.
Thus, according to an embodiment, the apparatus of the invention comprises: an electromagnetic inductor 28 having an electrode 27 disposed in the housing 21, but embodiments are also contemplated when the electrode is disposed outside the housing 21. The chlorine plasma may be maintained in the reaction zone, for example, by applying a static magnetic field that may be generated by an induction coil 26 disposed in the housing 21, although embodiments are also contemplated where the induction coil 26 is disposed outside of the housing 21. The application of an electromagnetic field generated by the decomposition of the chlorine-containing material to the chlorine-containing gas mixture ionizes the chlorine and forms a chlorine plasma, thereby causing a chemical reaction between the gold and chlorine ions and providing a volatile gold-containing chloride product in the reaction zone. Examples of such chemical reactions include, but are not limited to
2Au+3Cl2＝2AuCl3↑
Au+0.5Cl2＝AuCl。↑
The irradiance of the electromagnetic field in the reaction zone depends on the configuration of the apparatus, the volume of the mixture 25, and the pressure of the chlorine-containing gas mixture.
The pressure of the chlorine-containing gas mixture in the reaction zone may, for example, be in the range from 1 mbar to 1 bar. Under these conditions, for example, the ionization of chlorine molecules can be achieved by applying an alternating electromagnetic field to the reaction zone at a frequency in the range of 50kHz-12 GHz. The irradiance of the electromagnetic field in the reaction zone may be, for example, at 0.1kW/cm2To 10kW/cm2Within the range of (1).
To ionize the chlorine, an electromagnetic field may be applied to the chlorine containing gas mixture for a time period in the range of 5min to 180min, for example. The strength of the static magnetic field used to maintain the plasma in the reaction zone may be between 0 and 2 tesla.
According to an embodiment, the heating of the mixture of oxidized particulate material and chlorine-containing material in the reaction zone is performed while applying an electromagnetic field to the chlorine-containing gas mixture.
According to some embodiments, the reactor 22 comprises a chlorine-containing gas inlet port 223 coupled to a chlorine-containing gas inlet manifold 224 disposed in the housing wall 210 and configured for receiving chlorine-containing gas from an external source (not shown) and introducing a predetermined amount of chlorine-containing gas into the reaction zone. The chlorine-containing gas may be, for example, a gas mixture of chlorine and an inert gas such as argon; however, the gas mixture may also comprise nitrogen and/or oxygen.
In operation, chlorine-containing gases may pass through the reaction zone and be added to the chlorine-containing gas mixture produced from the chlorine-containing material to effect ionization. The amount of chlorine-containing gas from the external source passing through the reaction zone may for example be in the range of 5 to 400 litres of chlorine per tonne of said gold-containing material, such as electronic waste or minerals, ores and sand. This provision may facilitate a chemical reaction between gold and chloride ions. Chlorine-containing gases may be passed through the reaction zone, for example, during heating and application of an electromagnetic field.
When desired, a chlorine-containing gas inlet valve 225 may be disposed within the chlorine-containing gas inlet manifold 224. The chlorine-containing gas inlet valve 225 is configured to regulate the incoming flow rate of chlorine-containing gas. The term "valve" as used in this specification has a broad meaning and relates to any electrical and/or mechanical device suitable for regulating the flow rate of gases and liquids.
The apparatus 20 further comprises one or more gold-containing vapor outlets 226 (only one outlet 226 is shown in fig. 2), and one or more corresponding cooling manifolds 29 (only one cooling manifold 29 is shown in fig. 2) through which gold-containing vapor is released from the reaction zone 22. The cooling manifold 29 is configured for cooling the volatile gold-containing chloride product (i.e. gold-containing vapour) in order to provide condensation, thereby converting the volatile gold-containing chloride product into a solid-phase gold-containing material.
The cooling manifold 29 may be a tube made of a thermally conductive material that is open to the atmosphere and placed at room temperature. In this case, the cooling of the sulfur-containing vapor may be performed during the passage of the material through the cooling manifold 29. The cooling manifold 29 may be provided in a dedicated cooling device (not shown) when required.
The apparatus 20 may include a gold-bearing material collector 30 coupled to the gold-bearing vapor outlet 226 via a cooling manifold 29. The sulfur-containing material collector 30 can be any suitable vessel, such as a tank, canister, chamber, cassette, housing, frame, or any other structure that can be used to collect and store the solid phase material obtained during condensation of the volatile gold-containing chloride product in accordance with the teachings of the present invention.
The plant 20 may include or may be connected to a control system (not shown) coupled to the chlorine-containing gas inlet valve 225 and configured to control the operation thereof. Also, the control system may be adjusted to control the operation of the heater 221. In particular, the signal generated by the temperature sensor 222 may be relayed to a control system via a connection line (not shown) or in a wireless manner. In response to these signals, the control system may generate corresponding control signals to control the operation of the heater 221.
Gold may be recovered from the gold-bearing material in the solid phase by any recovery means conventional in the art. This can be conveniently achieved, for example, by dissolving the concentrated solid product containing gold in water and treating the solution with metallic zinc to reduce the gold.
As such, those skilled in the art to which the invention pertains, will appreciate that while the invention has been described in terms of preferred embodiments, the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structural systems and processes for carrying out the several purposes of the present invention.
Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
Finally, it is to be noted that the term "comprising" as used in the appended claims is to be interpreted as "including but not limited to".
The following examples are presented in order to more fully illustrate the preferred embodiments of the invention. However, these examples should in no way be construed as limiting the broad scope of the invention.
Examples of the invention
Example 1
Recovery of gold from gold-bearing materials
The low temperature chlorine sintering study was conducted on various industrial samples having gold contents of 4-12 ppm. The experiments were carried out in alumina crucibles at 200-350 ℃ in a furnace with a heating element (FeCrAl) from Kanthal. The initial sample was 60 g. Chlorine gas is used as the chlorine-containing reagent and is supplied to the furnace in considerable excess. The chlorine consumption was 10 ml/min. The duration of the experiment was 1 hour. For reproducibility of the experiments, each experiment was performed twice. The sublimated product is removed from the reaction zone by a gas stream.
The samples obtained after sintering were analyzed by ICP-MS spectroscopy. The yield of gold extracted from the product without arsenic and antimony (0.05% As, 0.003% Sb) was 80-90%. No sublimation of non-ferrous metals (Cu, Pb, Ag, Zn) and iron was detected.
Example 2
Recovery of gold from material containing arsenic, antimony and gold
The presence of arsenic, antimony or a combination thereof in gold-bearing materials has been found to drastically reduce the gold recovery from 90% to 30-40%.
To recover high levels of gold, arsenic and antimony are first removed from the product. The second stage of the process must be a selective gold extraction process as described in example 1.
During sintering of materials containing arsenic and antimony (0.6% As, 0.3% Sb), very high sublimation rates of arsenic and antimony (70-75%) were obtained. Meanwhile, the extraction amount of gold is sharply reduced to 30-40%.
To prevent the sublimation of arsenic and antimony, preliminary studies have been conducted to remove the arsenic and antimony from the starting materials in advance. Thermodynamic calculations were performed for all reactions. The preliminary ground sample was 60g (As-0.71%, Sb-0.65%, Cu-11%, Zn-3.7%, Pb-38%, Au-30ppm, Ag-100ppm, Fe-2.4%) and was mixed with coal and reduced at 500 deg.C, 700 deg.C and 900 deg.C. The coal consumption was 150% of the stoichiometric amount of coal required to completely reduce the arsenic and antimony oxides with carbon. The best results are obtained at temperatures of-700 ℃. Nearly complete selective arsenic and antimony sublimation (up to 99%) was obtained.
Sublimation of other non-ferrous metals has not been detected. Gold is almost completely retained in the clinker. Experimental results show that the technical process of sintering with chlorine must be accompanied by a preliminary stage of removal of arsenic and antimony from the starting material. Sintering of the starting material with coal will greatly increase the extraction of gold in the chloride form into commercial products.
It is important, therefore, that the scope of the invention be not construed as limited by the illustrative embodiments set forth herein. Other variations are possible within the scope of the invention as defined in the appended claims. Other combinations and subcombinations of features, functions, elements, and/or properties may be claimed through amendment of the present claims or presentation of claims in this or a related application. Such amended or new claims, whether they are directed to a different combination or directed to the same combination, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the present disclosure.