Removal of copper (Cu) from steel

Abstract

A process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below that of the second metal or alloy. Also disclosed is a process for separating steel from contaminants, such as copper. The process involves heating the first metal and the second metal or alloy to a temperature below the melting point of the second metal or alloy, followed by reacting the first metal with a halogen gas to form a metal halide that can be separated or to embrittle the first metal and separate the embrittled first metal from the second metal or alloy.

Description

[Technical Field]

[0001] The present specification relates to a process for the removal of a metal from a second metal or alloy. [Background technology]

[0002] The amount of steel discarded each year has increased over time, and to meet emissions targets, more steel must be produced from scrap. The presence of contaminants such as copper limits the amount of scrap steel that can be recycled to replace primary steel. Copper as a contaminant in steel is often manually separated from the steel when found in large components, but the majority of copper contamination remains as wiring in automobile scrap, household appliances, and equipment. Only a very small amount of steel (e.g., engine blocks and powder metallurgy products) has copper as part of the alloy. This means that copper extraction methods from steel should primarily focus on removing the copper wire.

[0003] Although different methods, including manual and magnetic separation, have been proposed and tested for the separation of copper from steel, achieving less than 0.4% by weight of copper in steel scrap remains a challenging task. In the solid state, copper removal is problematic due to physical mixing. In the molten state, copper is practically impossible to remove due to its relative nobility to iron. Daehn et al. (Metallurgical and Materials Transactions B, vol. 50B, 2019, pp. 1225-1240, incorporated herein by reference) disclose a different method for the removal of residual copper from steel.

[0004] There is a need in the art for a process for separating a first metal from a second metal or alloy. Additionally, there is a need in the art for a process for separating a first metal from a second metal or alloy, where the first metal has different physical properties, such as melting point, heat capacity, gas solubility, and thermal conductivity, from the second metal or alloy. Furthermore, there is a need in the art for a process that allows for recycling one or more reagents used to separate the first metal from the second metal or alloy. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Daehn et al. (Metallurgical and Materials Transactions B, vo. 50B, 2019, 1225-1240 Summary of the Invention

[0006] In a first aspect, the present specification discloses a process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the process comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; and c) separating the metal halide from the second metal or alloy.

[0007] In a second aspect, the present specification relates to a system for separating a first metal from a second metal or alloy, the first metal having a melting point below the melting point of the second metal or alloy, the system comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; Separating the metal halide from the second metal or alloy; reacting a metal halide to modify the first metal and halogen gas; and recycling the halogen gas.

[0008] In a third aspect, the present specification relates to a process for separating a first metal from a second metal or alloy, the process comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal; exposing the first metal to a gas to form an embrittlement of the first metal; and c) separating the embrittled first metal from the second metal or alloy.

[0009] In a fourth aspect, the present specification relates to a process for the preparation of steel, comprising one or more of the processes disclosed herein. [Brief explanation of the drawings]

[0010] Reference will now be made, by way of example, to the accompanying drawings which illustrate exemplary embodiments of the present application.

[0011] [Figure 1] 1 shows a steel production process with a reactive gas pretreatment step by direct resistance heating.

[0012] Similar reference numbers may be used in different figures to indicate similar components. DETAILED DESCRIPTION OF THE INVENTION

[0013] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present invention, exemplary materials and methods are described herein. In describing and claiming the present invention, the terms used are disclosed herein below.

[0014] As set forth herein, in a first aspect, the present specification discloses a process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the process comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; and c) separating the metal halide from the second metal or alloy.

[0015] As used herein, the term "first metal" is not particularly limited and should be understood or determined by one of ordinary skill in the art. In one embodiment, for example and without limitation, the first metal is copper (Cu). When used in the processes disclosed herein, the first metal has a melting point below that of the second metal or alloy, and the first metal is separated from the second metal or alloy. In the embodiments disclosed herein, copper has a melting point of approximately 1085°C.

[0016] As used herein, the term "second metal or alloy" is not particularly limited and should be understood or determined by one of ordinary skill in the art. In one embodiment, for example, but not by way of limitation, the second metal or alloy is steel. Steel is an alloy made of iron with the addition of carbon, along with other elements. Because steel is an alloy, the melting point of the steel can vary depending on the elements present in the alloy and can range from 1200°C to 1540°C. In one embodiment, for example, but not by way of limitation, the steel is scrap steel with copper intertwined with the steel, which cannot be easily separated manually.

[0017] The heating step disclosed herein with respect to the first aspect of the specification involves heating a first metal and a second metal or alloy to a temperature near the melting point of the first metal but below the melting point of the second metal or alloy. The heating step is performed to allow the first metal to react under conditions selected for the particular first metal and overall process design. In a first embodiment, the heating step as disclosed herein is performed using resistive heating. In a second embodiment, the heating step as disclosed herein is performed using direct resistive heating.

[0018] The basic principle of resistance heating is that when an electric current passes through any resistance, a power loss occurs that manifests itself in the form of heat. In other words, a material has some resistance that opposes or resists the flow of electric current through it. Due to this, there are electrical losses in the resistor, which are dissipated as heat. There are two types of resistance heating: direct resistance heating and indirect resistance heating. In one embodiment, as disclosed herein, copper is separated from scrap steel using direct resistance heating.

[0019] In direct resistance heating, an electric current is passed through the materials to be heated (a first metal and a second metal or alloy). In direct resistance heating, the materials act as a medium for the completion of an electric circuit. The resistance offered by the material to the flow of electric current results in ohmic losses (I2 R). In one embodiment, for example, but not by way of limitation, as disclosed herein, direct resistance heating is performed in a closed system by inserting graphite electrodes into each end of the steel scrap and passing an electric current through the material to create a voltage drop based on the resistance of the copper-containing steel scrap. This voltage drop generates heat, with higher resistance resulting in more energy. A schematic diagram of the process is shown in FIG. 1. To the inventors' knowledge, this type of heating has never been used before in the steel industry, although the type of furnace required for this process is similar to the Acheson furnace used to produce graphite. Therefore, in one embodiment, direct resistance heating is utilized to separate copper from scrap steel using the process steps disclosed in different aspects of the present specification.

[0020] The temperature to which the first metal and second metal or alloy are heated should be close to the melting point of the first metal and below the melting point of the second metal or alloy. Heating to such a temperature allows for preferential reaction of the first metal with the halogen gas, while the second metal or alloy remains primarily unreacted compared to the first metal. Furthermore, avoiding reaching the melting point of the second metal or alloy can help prevent the first metal from alloying with the second metal or alloy. In one embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 900°C to about 1,500°C, and all values ​​and ranges therebetween. In a second embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 1,000°C to about 1,200°C, and all values ​​and ranges therebetween. In a third embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 1,000°C to about 1,150°C, and all values ​​and ranges therebetween. In a fourth embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 1,050°C to about 1,150°C, and all values ​​and ranges therebetween.

[0021] The process of reacting a first metal with a halogen gas to form a metal halide is not particularly limited and is known or can be determined by one of ordinary skill in the art. In one embodiment, for example, but not limited to, the reaction is carried out in a reaction chamber containing a first metal and a second metal or alloy. In one embodiment, for example, but not limited to, the halogen gas is chlorine (Cl) or bromine (Br) gas. In further embodiments, for example, but not limited to, the ratio of halogen gas to first metal is about 0.01:1 to 1:1, 1:1 to 10:1, 1:1 to 3:1, and all values ​​and ranges therebetween. In certain embodiments, the ratio of halogen gas to first metal is about 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 0.9:1, 0.8:1, 0.7:1, 0.6:1, 0.5:1, 0.4:1, 0.3:1, 0.2:1, 0.1:1, 0.09:1, 0.08:1, 0.07:1, 0.06:1, 0.05:1, 0.04:1, 0.03:1, 0.02:1, or 0.01:1.

[0022] In another embodiment, for example, but not limited to, halogen gas is introduced into the reaction chamber via an inlet along with a carrier gas. In one embodiment, for example, but not limited to, the carrier gas is air or nitrogen. In further embodiments, for example, but not limited to, the ratio of carrier gas to halogen gas is about 5:1 to about 100:1, and all values ​​and ranges therebetween. In certain embodiments, the ratio of carrier gas to halogen gas is about 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, or 95:1.

[0023] A halogen gas can be introduced into a reaction chamber containing a first metal and a second metal or alloy and reacted with the first metal to form a metal halide. In one embodiment, reaction conditions are selected, for example, but not limited to, a residence time of the halogen gas in the reaction chamber (or reactor) for reacting the first metal with the halogen gas to form the metal halide of about 2 to about 60 minutes, and all values ​​and ranges therebetween. In a second embodiment, reaction conditions are selected, for example, but not limited to, a residence time of the halogen gas in the reaction chamber (or reactor) for reacting the first metal with the halogen gas to form the metal halide of about 10 to about 45 minutes, and all values ​​and ranges therebetween. In a third embodiment, for example, but not limited to, reaction conditions are selected such that the halogen gas has a residence time of about 15 to about 30 minutes, and all values ​​and ranges therebetween, in a reaction chamber (or reactor) for carrying out the step of reacting a first metal with a halogen gas to form a metal halide.

[0024] The reaction can be carried out under conditions such that the metal halide formed is in a gas phase and the second metal or alloy is in a solid phase, for example, but not limited to, conditions that vary depending on the first metal and the second metal or alloy, and are known or can be determined by one skilled in the art. In one embodiment, for example, but not limited to, when the first metal is copper and the second metal or alloy is steel, the pressure and / or temperature of the reaction conditions can be selected such that the copper halide formed is in a gas phase, which can allow the copper halide to be more easily separated from the steel, since the formed copper halide in the gas phase is exhausted from the reaction chamber along with the halogen gas and / or carrier gas.

[0025] The process for separating the metal halide from the second metal or alloy is not particularly limited. In one embodiment, for example, but not limited to, copper (as the first metal) reacts with chlorine gas or bromine gas in the reaction chamber to form copper(II) chloride (CuCl) or copper(II) bromide (CuBr), respectively. In such an embodiment, the reaction conditions (temperature and pressure) can be selected such that copper(II) chloride (CuCl) or copper(II) bromide (CuBr) is formed in the gas phase and can be removed using a carrier gas to allow the copper(II) chloride (CuCl) or copper(II) bromide (CuBr) to exit the reaction chamber through an outlet of the reaction chamber.

[0026] In one embodiment, the process disclosed herein includes recycling the halogen gas used to react with the first metal to form the metal halide. In a further embodiment, for example, but not limited to, the metal halide (e.g., copper chloride or copper bromide) formed during the reaction is separated from the second metal or alloy (scrap steel) and removed from the reaction chamber via an outlet within the reaction chamber, carried by a carrier gas. The separated metal halide can undergo separate reactions to convert the separated metal halide to the isolated first metal and reformed halogen gas. In one embodiment, for example, but not limited to, molten salt electrolysis can be used to convert the separated metal halide to the isolated first metal and reformed halogen gas. The reformed halogen gas can be recycled back to the reaction chamber for further reaction with the first metal.

[0027] In a second aspect according to the present specification, a system for separating a first metal from a second metal or alloy is disclosed, wherein the first metal has a melting point below the melting point of the second metal or alloy, the system comprising: heating a first metal and a second metal or alloy to a temperature close to the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; Separating the metal halide from the second metal or alloy; reacting a metal halide to modify the first metal and halogen gas; and recycling the halogen gas.

[0028] The system disclosed in the second aspect hereof includes the steps and process conditions of the first aspect of the process disclosed herein above, together with the steps and process conditions for recycling halogen gas as described above.

[0029] FIG. 1 illustrates an embodiment of the first and second aspects of the present disclosure, in which scrap steel (second metal or alloy) (10) is processed to remove copper (first metal) (or pre-treated to refine steel) in a reaction chamber (12). The scrap steel (10) is introduced into the reaction chamber (12). The reaction chamber (12) is connected to a halogen gas supply (14) and a carrier gas (not shown). An electrode (16) is electrically connected to the scrap steel (10) and directly heats the reaction chamber to 400°C to 1,300°C to carry out a reaction between the copper and the halogen gas to form copper halides, which are carried by the carrier gas (20) in the reaction chamber (12) to separate the copper from the scrap steel (10). The separated scrap steel can then be directed to an electric arc furnace (EAF) (18) for further processing and refining. The process of EAF 18 is not particularly limited and should be known to those skilled in the art. In EAF 18, the separated steel is heat treated using an electric arc at a temperature, which can reach a temperature of about 1,650°C.

[0030] In a third aspect, the present specification relates to a process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the process comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal; exposing the first metal to a gas that allows for the formation of an embrittlement of the first metal; and c) separating the embrittled first metal from the second metal or alloy.

[0031] The heating step disclosed herein with respect to the third aspect of the specification involves heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal to form an embrittlement of the first metal. The inventors have determined that the heating rate of the scrap metal and the selected atmosphere can affect the level of embrittlement of copper relative to the steel, and therefore the removal of copper from the steel scrap. This property of selectively or preferentially embrittling a first metal over a second metal or alloy using specific heating rates and / or atmospheric conditions can be exploited when separating the first metal (impurity) from the target second metal or alloy. Therefore, by selecting the heating rate and / or atmospheric conditions, preferential embrittlement of copper over steel can be achieved. This is due to the preferential reaction of copper with steel. In one embodiment, the reaction leads to preferential oxidation of copper over steel, thereby facilitating the separation of copper from the steel.

[0032] As generally described above, depending on the composition of the copper-containing steel scrap, the heating rate can be selected to allow preferential embrittlement of the copper over the steel and minimize reaction with the steel. In one embodiment, for example, but not limited to, the copper-containing steel scrap is heated rapidly to achieve preferential embrittlement of the copper over the steel. In a second embodiment, for example, but not limited to, the steel scrap is heated at a rate of at least about 30°C / min. In a third embodiment, for example, but not limited to, the steel scrap is heated at a rate of about 35°C / min, 40°C / min, 45°C / min, 50°C / min, 55°C / min, 60°C / min, 65°C / min, 70°C / min, 75°C / min, 80°C / min, 85°C / min, 90°C / min, 95°C / min, or 100°C / min.

[0033] In one embodiment, copper-containing scrap steel is heated to allow preferential reaction (e.g., oxidation) of the copper over the scrap steel, leading to copper embrittlement. It has been found that direct heating (such as with a gas burner, which affects the volume and oxidation state of the gas) or indirect heating (which heats through a barrier and takes a long time to heat at significant power costs) can lead to the copper alloying with the steel, making removal more difficult. By selecting a heating method that avoids alloying the copper with the steel scrap, which can cause copper embrittlement, the copper can be more easily separated. One example of such a heating method is, but is not limited to, resistance heating. Another method involves, for example, but not limited to, direct resistance heating.

[0034] In a first embodiment, as disclosed herein, the heating step is carried out using resistance heating, as described herein above. In a second embodiment, as disclosed herein, the heating step is carried out using direct resistance heating, as described herein above. In a third embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 500°C to about 1,000°C, and all values ​​and ranges therebetween. In a fourth embodiment, for example, but not limited to, steel scrap (second metal or alloy) containing copper (first metal) is heated to a temperature of about 600°C to about 900°C, and all values ​​and ranges therebetween. The selected temperature is below the melting point of copper to inhibit alloying of copper into the steel.

[0035] The heating time for the scrap steel with copper is not particularly limited and can vary depending on design and application requirements, but care must be taken to avoid alloying of the copper into the steel, and the heating time should be consistent with the tap-to-tap time in the electric arc furnace (EAF) operation in which the steel is further processed. In one embodiment, for example, but not limited to, the heating time for the scrap steel and copper is about 5 to about 30 minutes, and all values ​​and ranges therebetween. In a second embodiment, for example, but not limited to, the heating time for the scrap steel and copper is about 10 to about 25 minutes, or about 15 to about 20 minutes, and all values ​​and ranges therebetween. In a third embodiment, for example, but not limited to, the heating time for the scrap steel and copper is up to about 30 minutes.

[0036] In one embodiment, the atmosphere of the reaction chamber for carrying out the heating can be controlled to enable preferential embrittlement of copper. In a further embodiment, for example and without limitation, the process is carried out in an atmosphere containing one or more of air, enriched air containing up to 100% oxygen (O), nitrogen (N), carbon monoxide (CO), carbon dioxide (CO), chlorine (Cl) gas, and bromine (Br) gas. In another further embodiment, for example and without limitation, the partial pressure, flow rate, and embrittlement-causing oxygen or halogen supply of the reactive gas can be controlled to enable preferential embrittlement of copper relative to steel. Controlling the reactive gas as described above can allow non-copper (i.e., steel or iron) to not react, react minimally, or react at a ratio below the copper-to-steel ratio, which can aid in preferential embrittlement of copper over steel. Under such conditions, the reactive gas reacts with steel or copper to a greater extent than the copper-to-steel ratio, leading to preferential embrittlement of copper over steel.

[0037] As used herein, the term "embrittlement" is not particularly limited and should be known or understood by those skilled in the art. In one embodiment, for example, but not limited to, embrittlement involves the preferential reaction of oxygen with copper over steel. In certain embodiments, for example, but not limited to, oxygen can be present in copper. In another embodiment, for example, but not limited to, embrittlement creates a significant decrease in the ductility of copper, allowing the copper to break down into powder with light to moderate stirring and / or grinding.

[0038] Various factors contribute to the embrittlement of metals. These factors include heat capacity, gas solubility, and thermal conductivity. Based on differences in these factors between the first and second metals or alloys, temperature and pressure conditions can be selected to allow preferential embrittlement of the first metal over the second metal or alloy. Once embrittled, the first metal can be more easily separated from the second metal or alloy.

[0039] The process for separating the embrittled first and second metals or alloys is not special and can vary depending on design and application requirements. After heating the first and second metals or alloys under conditions that embrittle the first metal (e.g., copper), the first and second metals or alloys can be shaken, stirred, gently crushed, or vibrated to separate the first metal from the second metal or alloy.

[0040] An embodiment of the third aspect is further described. In this embodiment, the steel is heated with direct electricity, either AC or DC, in a sealed unit that can be compressed by electrode plates at both ends to ensure contact with the steel scrap throughout the heating period. Heat is generated by both material resistance and radiative heat transfer from the material to the reactor surroundings. The steel can be rapidly heated to several hundred degrees below the melting point of copper. This promotes embrittlement of the copper during rapid heating, while maintaining atmospheric control and preventing alloying into the steel. The focus for copper removal is wire that is somehow attached to the steel scrap. Larger copper pieces are typically removed by hand sorting or eddy current. Once heated, the charge is shaken / vibrated, and smaller, embrittled solids are collected from the bottom of the heater. The hot charge can then be transferred to the EAF for melting. The heating chamber can be designed to maintain the steel temperature as needed, such as by using EAF off-gas as an energy source to maintain the temperature of the chamber.

[0041] The embrittled solids can then be physically separated from the steel while still in the reactor or immediately during transport to the EAF. One way to accomplish this is by shaking or vibrating the reactor during or after heating. Another method is to use vibration during material transport, but requires heat retention. The solids are collected after transport or through an opening in the bottom of the chamber.

[0042] The atmosphere can be a combination of air, nitrogen, CO2, and chlorine. The inventors have found that rapid heating of the steel preferentially embrittles the copper without significant oxidation of the steel.

[0043] When introducing elements disclosed herein, the articles "a," "an," "the," and "said" are intended to mean that there may be one or more of the element.

[0044] As used herein, the term "comprise" and its derivatives are intended to be open-ended terms specifying the presence of stated features, elements, components, groups, integers, and / or steps, but not excluding the presence of other, unstated features, elements, components, groups, integers, and / or steps. The foregoing also applies to words of similar meaning, such as "comprise," "have," and their derivatives. Any embodiment described as "comprising" certain components may also "consist" or "consist essentially of" those components, with "consisting" having a restrictive or limiting meaning, and "consisting essentially of" being understood to mean including the specified components, but excluding materials present as impurities, unavoidable materials present as a result of the process used to provide the components, and components added for purposes other than achieving the technical effects described herein.

[0045] It will be understood that any element defined as included herein may be expressly excluded from the claimed invention by a disclaimer or negative limitation, such as any particular compound or method step, whether expressly or implicitly defined herein.

[0046] In addition, all ranges set forth herein include the end points of the ranges and any intermediate range points, whether or not explicitly stated.

[0047] Finally, terms of degree, such as "substantially," "about," and "approximately," as used herein, refer to a reasonable amount of deviation from the modified term so that the end result is not materially altered. These terms of degree should be construed to include a deviation of at least ±5% from the modified term if this deviation does not negate the meaning of the word it modifies.

[0048] The abbreviation "for example" is derived from the Latin exempli gratia and is used herein to indicate a non-limiting example. Thus, the abbreviation "eg" is synonymous with the term "for example." The word "or" is intended to include "and" unless the context clearly indicates otherwise.

[0049] The phrase "at least one of" is understood to mean one or more. The phrase "at least one of ... and ...," if not explicitly listed, is understood to mean at least one of the listed elements or a combination thereof. For example, "at least one of A, B, and C" is understood to mean A alone, or B alone, or C alone, or A and B in combination, or A and C in combination, or B and C in combination, or A, B, and C in combination. [Example]

[0050] Example 1: Experimental setup and methodology Reactive gas experiments were conducted to test the effectiveness of copper removal by halogenation. Steel scrap was heated by loading the steel (0.5 wt.% Cu wire) into a crucible, enclosed within a reactor tube. The top of the reactor housed gas inlets for both air or N2, CO and CO2 (if applicable), and either Cl2 or Br2 halogen gases. Gas inlets were connected to gas injection lances to deliver gas from the bottom of the sample. An off-gas line was connected to capture the reacted solids.

[0051] The steel charge is removed from the reactor after the test is completed and melted. Melt samples are taken and analyzed for elemental Cu and Fe content.

[0052] It is worth noting that the furnace used for these experiments uses indirect resistance heating to heat the steel, whereby electricity is passed through resistance heating coils on the outside of the reactor tube. The high resistance of these coils converts the electricity into heat, which is then transferred by radiation to the steel inside the reactor tube.

[0053] This technology preferably utilizes a heating method that is not dependent on the use or release of carbon. Passing electricity through steel can heat it sufficiently to melt copper. However, the use of electrical heating in any capacity (i.e., direct or indirect resistance heating, or another form of heat generation that does not use carbon as a fuel) is an embodiment of this technology.

[0054] result Table 1 provides a summary of all test conditions and the resulting copper removal as a percentage. The different variables listed include the type of atmosphere (i.e., inert or oxidizing), the halogen to copper ratio (on a molar basis), and the test duration. The operating conditions that were varied in these tests are listed below: Halogen: Cl2 or Br2 Cu content: 0.5% by weight Stoichiometric ratio of halogen to copper: 1:1 to 3:1 Carrier gas to halogen ratio: 10:1, 20:1 Residence time: 15 to 30 minutes Temperature: 1050-1200°C, although the selective melting window for Cu is approximately 1100-1500°C. CO:CO2 ratio: 10% [Table 1]

[0055] The results from Table 1 show the removal of copper by using halogen gases. In addition, the use of an inert atmosphere (nitrogen) and chlorine significantly removed copper from the steel scrap.

[0056] Example 2: For heating experiments, metal loads were prepared consisting of copper and steel wires of various thicknesses. Wires ranging in thickness from 8 to 18 AWG were compressed vertically between two stainless steel rods welded to steel plates—each rod connected to a power source by a copper lead. These steel plates, with the metal sample between them, were sealed within an insulated ceramic reactor (commercial reactor construction, despite the different materials, is effective for bench-scale testing). Multiple gas inlet lines were installed at the bottom of the vertical reactor to allow for maximum gas residence time and enhanced gas / solid contact.

[0057] Once powered on, gas flow was on for a specified time. The metal charge was heated over a 10-30 minute time frame to reach an internal reactor temperature of 500-1000°C from room temperature. Input voltages of 1-8 V and currents of 0-300 A were used (suitable for charge sizes of a few hundred grams - much higher power would be required for charge sizes in the ton range).

[0058] Once cooled, the metal was removed from the reactor and characterization of the embrittlement effect from the present invention was performed by shaking and / or grinding to separate the embrittled copper from the steel and collect it by gravity.

[0059] The following are examples of test conditions:

[0060] A few hundred grams of steel are heated to 500-800°C for 30 minutes in an oxidizing atmosphere, with air flowing at 200 mL / min starting from room temperature, and copper embrittlement due to rapid heating and oxidation is evaluated after the test period.

[0061] A few hundred grams of steel are heated to 500-800°C for 30 minutes in an oxidizing atmosphere, with N2 flowing at 200 mL / min starting from room temperature, and copper embrittlement due to rapid heating and oxidation is evaluated after the test period.

[0062] Terms 1. A process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the process comprising: heating a first metal and a second metal or alloy to a temperature close to the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; and separating the metal halide from the second metal or alloy.

[0063] 2. The process of clause 1, wherein electrical heating is performed to heat the first metal and the second metal or alloy.

[0064] 3. The process according to clause 1 or 2, wherein the electrical heating is carried out by direct resistance heating.

[0065] 4. The process of any one of clauses 1 to 3, wherein the first metal is copper.

[0066] 5. The process of any one of clauses 1 to 4, wherein the second metal or alloy is steel.

[0067] 6. The process of any one of clauses 1 to 5, wherein the heating step is carried out at a temperature of from about 900°C to about 1500°C.

[0068] 7. The process of any one of clauses 1 to 5, wherein the heating step is carried out at a temperature of about 1000°C to about 1200°C.

[0069] 8. The process of any one of clauses 1 to 7, wherein the halogen gas is chlorine gas or bromine gas.

[0070] 9. The process of any one of clauses 1-8, wherein the formed metal halide is in a gas phase and the second metal or alloy is in a solid phase, and the process further comprises removing the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

[0071] 10. The process of any one of clauses 1 to 9, further comprising, after separation of the metal halide, reacting the metal halide to isolate the first metal from the second metal or alloy and reforming the halogen gas.

[0072] 11. The process of claim 10, further comprising recycling the halogen gas.

[0073] 12. The process of any one of clauses 1-11, wherein the ratio of halogen gas to first metal is from about 1:1 to about 10:1.

[0074] 13. The process of any one of clauses 1-11, wherein the ratio of halogen gas to first metal is from about 1:1 to about 3:1.

[0075] 14. The process of any one of clauses 1 to 13, further comprising a carrier gas.

[0076] 15. The process of clause 14, wherein the carrier gas is air or nitrogen.

[0077] 16. The process of clause 14 or 15, wherein the ratio of carrier gas to halogen gas is from about 5:1 to about 100:1.

[0078] 17. The process of any one of clauses 1 to 16, wherein the halogen gas has a residence time of about 10 to about 60 minutes in a reactor for carrying out the step of reacting the first metal with the halogen gas to form a metal halide.

[0079] 18. A system for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the system comprising: heating a first metal and a second metal or alloy to a temperature close to the melting point of the first metal and below the melting point of the second metal or alloy; reacting a first metal with a halogen gas to form a metal halide; Separating the metal halide from the second metal or alloy; reacting a metal halide to modify the first metal and halogen gas; and recycling the halogen gas.

[0080] 19. The system of clause 18, wherein electrical heating is performed to heat the first metal and the second metal or alloy.

[0081] 20. A system according to clause 18 or 19, wherein the electrical heating is carried out by direct resistance heating.

[0082] 21. The system of any one of clauses 18 to 20, wherein the first metal is copper.

[0083] 22. The system of any one of clauses 18-21, wherein the second metal or alloy is steel.

[0084] 23. The system of any one of clauses 18-22, wherein the heating step is carried out at a temperature of about 900°C to about 1400°C.

[0085] 24. The system of any one of clauses 18 to 23, wherein the heating step is carried out at a temperature of about 1000°C to about 1200°C.

[0086] 25. A system according to any one of clauses 18 to 24, wherein the halogen gas is chlorine gas or bromine gas.

[0087] 26. The system of any one of clauses 18 to 25, wherein the metal halide formed is in the gas phase and the second metal or alloy is in the solid phase.

[0088] 27. The system of any one of clauses 18-26, wherein the ratio of halogen gas to first metal is from about 1:1 to about 10:1.

[0089] 28. The system of any one of clauses 18-27, wherein the ratio of halogen gas to first metal is from about 1:1 to about 3:1.

[0090] 29. The system of any one of clauses 18 to 28, further comprising a carrier gas.

[0091] 30. The system of clause 29, wherein the carrier gas is air or nitrogen.

[0092] 31. The system of clause 29 or 30, wherein the ratio of carrier gas to halogen gas is from about 5:1 to about 100:1.

[0093] 32. The system of any one of clauses 18 to 31, wherein the halogen gas has a residence time of 10 to 60 minutes in the reactor for carrying out the step of reacting the first metal with the halogen gas to form a metal halide.

[0094] 33. A process for separating a first metal from a second metal or alloy, comprising: heating a first metal and a second metal or alloy to a temperature below the melting point of the first metal; exposing the first metal to a gas to form an embrittlement of the first metal; and separating the embrittled first metal from the second metal or alloy.

[0095] 34. The process of clause 33, wherein electrical heating is performed to heat the first metal and the second metal or alloy.

[0096] 35. The process of clause 33 or 34, wherein direct resistance heating is used to carry out the heating step.

[0097] 36. The process of any one of clauses 33-35, wherein the heating step has a minimum heating rate of about 30°C / min.

[0098] 37. The process of any one of clauses 33-36, wherein the heating step is carried out for about 5 to about 30 minutes.

[0099] 38. The process of any one of clauses 33-37, wherein the process is carried out in an atmosphere containing one or more of air, enriched air containing up to 100% oxygen, nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), chlorine (Cl2) gas, and bromine (Br2) gas.

[0100] 39. The process of any one of clauses 33 to 38, wherein the first metal is copper.

[0101] 40. The process of any one of clauses 33 to 39, wherein the second metal or alloy is steel.

[0102] 41. The process of any one of clauses 33-40, wherein the heating step is carried out at a temperature of about 500°C to about 1000°C.

[0103] 42. The process of any one of clauses 33-41, wherein the atmosphere contains chlorine gas or bromine gas, and heating the first metal forms a metal halide in a gas phase, and the process further comprises removing the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

[0104] 43. The process of clause 42, further comprising, after separation of the metal halide, reacting the metal halide to isolate the first metal from the second metal or alloy and reforming the chlorine or bromine gas.

[0105] 44. The process of clause 43, further comprising recycling the chlorine or bromine gas.

[0106] 45. The process of any one of clauses 33-44, wherein the first metal and the second metal or alloy are milled to separate the first metal from the second metal or alloy.

[0107] 46. ​​The process of any one of clauses 33-45, wherein shaking, grinding, or trolling is performed to separate the first metal from the second metal.

[0108] 47. A process for the preparation of steel, including a process as defined in any one of clauses 1 to 47.

[0109] 48. The process of clause 47, further comprising directing the separated second metal or alloy to an electric arc furnace.

[0110] The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the examples. These examples are set forth for illustrative purposes only and are not intended to limit the scope of the invention. Modifications in form and substitution of equivalents are contemplated where the circumstances suggest or make appropriate. Without further explanation, it is believed that one of ordinary skill in the art can, using the foregoing description and illustrative examples, make and utilize the constructs of the present invention and practice the claimed methods. The examples, therefore, specifically point out exemplary aspects of the present invention and should not be construed as limiting in any way to the remainder of the disclosure. Although specific terms are used herein, such terms are intended in a descriptive sense and not for purposes of limitation.

[0111] All publications, patents, and patent applications cited above are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

[0112] While preferred embodiments of the present invention have been described in detail herein, it will be understood by those skilled in the art that variations may be made without departing from the spirit of the invention or the scope of the appended claims. Accordingly, the embodiments discussed above are considered to be illustrative and not limiting.

Claims

1. 1. A process for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the process comprising: heating the first metal and the second metal or alloy to a temperature close to the melting point of the first metal and below the melting point of the second metal or alloy; reacting the first metal with a halogen gas to form a metal halide; and separating said metal halide from said second metal or alloy.

2. The process of claim 1 , wherein electrical heating is performed to heat the first metal and the second metal or alloy.

3. 3. The process of claim 1 or 2, wherein the electrical heating is performed by direct resistance heating.

4. The process of any one of claims 1 to 3, wherein the first metal is copper.

5. The process of any one of claims 1 to 4, wherein the second metal or alloy is steel.

6. The process of any one of claims 1 to 5, wherein the heating step is carried out at a temperature of from about 900°C to about 1500°C.

7. The process of any one of claims 1 to 5, wherein the heating step is carried out at a temperature of from about 1000°C to about 1200°C.

8. The process of any one of claims 1 to 7, wherein the halogen gas is chlorine gas or bromine gas.

9. 9. The process of any one of claims 1 to 8, wherein the metal halide formed is in a gas phase and the second metal or alloy is in a solid phase, and the process further comprises removing the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

10. 10. The process of any one of claims 1 to 9, further comprising, after separation of the metal halide, reacting the metal halide to isolate the first metal from the second metal or alloy and to reform the halogen gas.

11. 11. The process of claim 10, further comprising recycling the halogen gas.

12. 12. The process of any one of claims 1 to 11, wherein the ratio of the halogen gas to the first metal is from about 1:1 to about 10:

1.

13. 12. The process of any one of claims 1 to 11, wherein the ratio of the halogen gas to the first metal is from about 1:1 to about 3:

1.

14. The process of any one of claims 1 to 13, further comprising a carrier gas.

15. 15. The process of claim 14, wherein the carrier gas is air or nitrogen.

16. 16. The process of claim 14 or 15, wherein the ratio of the carrier gas to the halogen gas is from about 5:1 to about 100:

1.

17. 17. The process of any one of claims 1 to 16, wherein the halogen gas has a residence time of about 10 to about 60 minutes in a reactor for carrying out the step of reacting the first metal with the halogen gas to form the metal halide.

18. 1. A system for separating a first metal from a second metal or alloy, wherein the first metal has a melting point below the melting point of the second metal or alloy, the system comprising: heating the first metal and the second metal or alloy to a temperature approaching the melting point of the first metal; reacting the first metal with a halogen gas to form a metal halide; separating the metal halide from the second metal or alloy; reacting the metal halide to modify the first metal and the halogen gas; and recycling the halogen gas.

19. 20. The system of claim 18, wherein electrical heating is performed to heat the first metal and the second metal or alloy.

20. 20. The system of claim 18 or 19, wherein the electrical heating is performed by direct resistance heating.

21. The system of any one of claims 18 to 20, wherein the first metal is copper.

22. The system of any one of claims 18 to 21, wherein the second metal or alloy is steel.

23. The system of any one of claims 18 to 22, wherein the heating step is carried out at a temperature of from about 900°C to about 1400°C.

24. The system of any one of claims 18 to 23, wherein the heating step is carried out at a temperature of about 1000°C to about 1200°C.

25. The system according to any one of claims 18 to 24, wherein the halogen gas is chlorine gas or bromine gas.

26. 26. The system of any one of claims 18 to 25, wherein the metal halide formed is in a gas phase and the second metal or alloy is in a solid phase.

27. 27. The system of any one of claims 18 to 26, wherein the ratio of the halogen gas to the first metal is from about 1:1 to about 10:

1.

28. 28. The system of any one of claims 18 to 27, wherein the ratio of the halogen gas to the first metal is from about 1:1 to about 3:

1.

29. The system of any one of claims 18 to 28, further comprising a carrier gas.

30. 30. The system of claim 29, wherein the carrier gas is air or nitrogen.

31. 31. The system of claim 29 or 30, wherein the ratio of the carrier gas to the halogen gas is from about 5:1 to about 100:

1.

32. 32. The system of claim 18, wherein the halogen gas has a residence time of 10 to 60 minutes in a reactor for carrying out the step of reacting the first metal with the halogen gas to form the metal halide.

33. 1. A process for separating a first metal from a second metal or alloy, comprising: heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal; exposing the first metal to a gas to form an embrittlement of the first metal; and separating the embrittled first metal from the second metal or alloy.

34. 34. The process of claim 33, wherein electrical heating is performed to heat the first metal and the second metal or alloy.

35. 35. The process of claim 33 or 34, wherein direct resistive heating is used to carry out the heating step.

36. 36. The process of any one of claims 33 to 35, wherein the heating step has a minimum heating rate of about 30°C / min.

37. 37. The process of any one of claims 33 to 36, wherein the heating step is carried out for a period of from about 5 to about 30 minutes.

38. The process may be carried out using air, enriched air containing up to 100% oxygen, nitrogen (N ２ ), carbon monoxide (CO), carbon dioxide (CO ２ ), chlorine (Cl ２ ) gas, and bromine (Br ２ 38. The process of any one of claims 33 to 37, carried out in an atmosphere containing one or more of the following gases:

39. The process of any one of claims 33 to 38, wherein the first metal is copper.

40. 40. The process of any one of claims 33 to 39, wherein the second metal or alloy is steel.

41. The process of any one of claims 33 to 40, wherein the heating step is carried out at a temperature of from about 500°C to about 1050°C.

42. 42. The process of any one of claims 33 to 41, wherein the atmosphere contains chlorine gas or bromine gas, and heating the first metal forms a metal halide in a gas phase, and the process further comprises removing the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

43. 43. The process of claim 42, further comprising, after separation of the metal halide, reacting the metal halide to isolate the first metal from the second metal or alloy and reform the chlorine or bromine gas.

44. 44. The process of claim 43, further comprising recycling the chlorine or bromine gas.

45. 45. The process of any one of claims 33 to 44, wherein the first metal and second metal or alloy are milled to separate the first metal from the second metal or alloy.

46. 46. ​​The process of any one of claims 33 to 45, wherein shaking, grinding, or trolling is performed to separate the first metal from the second metal.

47. A process for the preparation of steel, comprising a process as defined in any one of claims 1 to 47.

48. 48. The process of claim 47, further comprising directing the separated second metal or alloy to an electric arc furnace.

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