Copper (CU) removal from steel

Abstract

A process for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy. Also, disclosed is a process for separation of 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 reaction of the first metal with a halogen gas to form a metal halide that can be separated, or embrittling of the first metal and separating the embrittled first metal from the second metal or alloy.

Description

COPPER (Cu) REMOVAL FROM STEELFIELD

[0001] The specification relates to a process for removal of a metal from a second metal or alloy.BACKGROUND

[0002] The amount of steel being discarded on a yearly basis has been increasing over time, and more steel must be produced from scrap to meet emissions targets. 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 hand-picked from steel if found as large components, leaving the vast majority of the copper contamination as wiring in automotive scrap, 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 an extraction method for copper from steel should predominately focus on the removal of copper wire.

[0003] Different methods have been proposed and tested for separation of copper from steel, including manual and magnetic separation; however, this has remained a challenging task, particularly in obtaining less than 0.4 wt. % copper in steel scrap. In the solid state, removing copper is problematic due to physical intermixing. In the molten state, copper is effectively impossible to remove due to its relative nobility to iron. Daehn et al. (Metallurgical and Materials Transactions B, vo. 50B, 2019, 1225-1240, incorporated herein by reference) disclose different methods for removal of residual copper from steel.

[0004] There is a need in the art for a process for separation of a first metal from a second metal or alloy. In addition, there is a need in the art for a process for separation of a first metal from a second metal or alloy, wherein the first metal has a different physical properties, such as, melting point, heat capacity, gas solubility, and thermal conductivity, than the second metal or alloy. Further, there is a need in the art for a process wherein the one or more reagents used to separate the first metal from the second metal or alloy can be recycled.SUMMARY OF THE SPECIFICATION

[0005] In a first aspect, the specification discloses a process for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the process containing the steps of:

[0006] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal and less than the melting point of the second metal or alloy;

[0007] reacting the first metal with a halogen gas to form a metal halide; and

[0008] separating the metal halide from the second metal or alloy.

[0009] In a second aspect, the specification relates to a system for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the system comprising of:

[0010] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal and less than the melting point of the second metal or alloy;

[0011] reacting the first metal with a halogen gas to form a metal halide;

[0012] separating the metal halide from the second metal or alloy;

[0013] reacting the metal halide to reform the first metal and the halogen gas; and

[0014] recycling the halogen gas.

[0015] In a third aspect, the specification relates to a process for separation of a first metal from a second metal or alloy, the process comprising the steps of:

[0016] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal;

[0017] exposing the first metal to a gas allowing to form an embrittled first metal;

[0018] separating the embrittled first metal from the second metal or alloy.

[0019] In a fourth aspect, the specification relates to a process for preparation of steel, containing one or more of the processes disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:

[0021] Figure 1 shows a steel production process with reactive gas pre-treatment stage by direct resistance heating.

[0022] Similar reference numerals may have been used in different figures to denote similar components.DESCRIPTION OF EXAMPLE EMBODIMENTS

[0023] 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, the typical materials and methods are described herein. In describing and claiming the present invention, the terminology used is disclosed herein below.

[0024] As noted herein, in a first aspect, the specification discloses a process for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the process containing the steps of:

[0025] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal and less than the melting point of the second metal or alloy;

[0026] reacting the first metal with a halogen gas to form a metal halide; and

[0027] separating the metal halide from the second metal or alloy.

[0028] The term "first metal" as used herein is not particularly limited and should be understood by a person of skill in the art, or can be determined. In one embodiment, for example and without limitation, the first metal is copper (Cu). The first metal as used in the process disclosed herein has a melting point below the melting point of the second metal or alloy, from which the first metal is to be separated. In the embodiment disclosed herein, copper has a melting point of about 1085°C.

[0029] The term "second metal or alloy" as used herein is not particularly limited and should be understood by a person of skill in theart, or can be determined. In one embodiment, for example and without limitation, the second metal or alloy is steel. Steel is an alloy made of iron with added carbon, along with other elements. As steel is an alloy, the melting point of steel can vary depending upon the elements presents in the alloy, and can range 1200°C-1540°C. In one embodiment, for example and without limitation, the steel is scrap steel that has copper entangled with the steel, and cannot be easily separated manually.

[0030] The step of heating as disclosed herein with respect to the first aspect of the specification involves heating the first metal and the second metal or alloy to a temperature close to the melting point of the first metal but below the melting point of the second metal or alloy. The step of heating is carried out to allow for the first metal to react under the conditions selected for the particular first metal, and the overall process design. In a first embodiment, as disclosed herein, the step of heating is carried out using resistance heating. In a second embodiment, as disclosed herein, the step of heating is carried out using direct resistance heating.

[0031] The basic principle of resistance heating is that, when current passes through some resistance, power loss takes place which appears in the form of heat. Stated another way, materials have some resistance that opposes or resists the flow of electrical current through it. Due to this, there will be electrical losses in the resistor which are dissipated as heat. There are two types of resistance heating, namely, direct resistance heating and indirect resistance heating. In one embodiment, as disclosed herein, the copper is separated from scrap steel using direct resistance heating.

[0032] In direct resistance heating, current is passed through the material (the first metal and the second metal or alloy) to be heated. In direct resistance heating, the materials act as a medium for the completion of the electrical circuit. Resistance offered by the materials tothe flow of current produces ohmic losses (I2R) resulting in heating of the materials. In one embodiment, for example and without limitation, as disclosed herein, direct resistance heating is carried out by the insertion of graphite electrodes at each end of the steel scrap in a closed system, and passing a current through the material that results in a voltage drop based on the resistance of steel scrap containing the copper. This voltage drop generates heat, with a higher resistance resulting in more energy. A schematic of the process is shown in Figure 1. To the knowledge of the inventors, this type of heating has not been previously used in the steel industry; however, the type of furnace required for this process is similar to the Acheson Furnace, used to make graphite. As such, in one embodiment, direct resistance heating is utilized for separation of copper from scrap steel using the process steps as disclosed in the different aspects herein.

[0033] 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 less than 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 predominantly unreacted in comparison to the first metal. In addition, avoiding reaching the melting point of the second metal or alloy, can help to avoid alloying of the first metal with the second metal or alloy. In one embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper (first metal) is heated to a temperature of from about 900°C to about l,500°C, and all values and ranges in between. In a second embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper (first metal) is heated to a temperature of from about l,000°C to about l,200°C, and all values and ranges in between. In a third embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper(first metal) is heated to a temperature of from about l,000°C to about l,150°C, and all values and ranges in between. In a fourth embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper (first metal) is heated to a temperature of from about l,050°C to about l,150°C, and all values and ranges in between.

[0034] The step of reacting the first metal with a halogen gas to form a metal halide is not particularly limited, and should be known to a person of skill in the art, or can be determined. In one embodiment, for example and without limitation, the reaction is carried out in a reaction chamber containing the first metal and second metal or alloy. In one embodiment, for example and without limitation, the halogen gas is chlorine (Ch) or bromine (Brz) gas. In a further embodiment, for example and without limitation, the ratio of the halogen gas to the first metal is from about 0.01:1 to 1:1, 1: 1 to 10:1, 1: 1 to 3: 1, and all values and ranges in between. In a particular embodiment, the ratio of the halogen gas to the 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.

[0035] In another embodiment, for example and without limitation, the halogen gas is introduced, along with a carrier gas, in the reaction chamber via an inlet. In one embodiment, for example and without limitation, the carrier gas is air or nitrogen. In a further embodiment, for example and without limitation, the ratio of the carrier gas to the halogen gas is from about 5:1 to about 100:1, and all values and ranges in between. In a particular embodiment, the ratio of the carrier gas to the 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.

[0036] The halogen gas can be introduced in the reaction chamber containing the first metal and second metal or alloy, to react with the first metal to form a metal halide. In one embodiment, for example andwithout limitation, the reaction conditions are selected that the halogen gas has a residence time of from about 2 to about 60 minutes, and all values and ranges in between, in the reaction chamber (or reactor) for carrying out the step of reacting the first metal with the halogen gas to form the metal halide. In a second embodiment, for example and without limitation, the reaction conditions are selected that the halogen gas has a residence time of from about 10 to about 45 minutes, and all values and ranges in between, in the reaction chamber (or reactor) for carrying out the step of reacting the first metal with the halogen gas to form the metal halide. In a third embodiment, for example and without limitation, the reaction conditions are selected that the halogen gas has a residence time of from about 15 to about 30 minutes, and all values and ranges in between, in the reaction chamber (or reactor) for carrying out the step of reacting the first metal with the halogen gas to form the metal halide.

[0037] The reaction can be carried out under conditions, for example and without limitation, where the metal halide formed is in a gas phase, and the second metal or alloy is in a solid phase. Such conditions can vary depending upon the first metal and second metal or alloy, and should be known or can be determined by a person of skill in the art. In one embodiment, for example and without limitation, where 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 gaseous phase, which can allow for easier separation of the copper halide from the steel, as the gaseous copper halide formed will exit out of the reaction chamber, along with the halogen gas and / or carrier gas.

[0038] The step of separating the metal halide from the second metal or alloy is not particularly limited. In one embodiment, for example and without limitation, the copper (as the first metal) reacts with chlorine or bromine gas in the reaction chamber to form copper (II) chloride (CuCh)or copper (II) bromide (CuBrz), respectively. In such an embodiment, the reaction conditions (temperature and pressure) can be selected to allow for formation of the copper (II) chloride (CuCh) or copper (II) bromide (CuBrz) in a gaseous phase, to allow for removal of the copper (II) chloride (CuCh) or copper (II) bromide (CuBrz) using the carrier gas, to exit the reaction chamber from an outlet of the reaction chamber.

[0039] In one embodiment, the process disclosed herein includes recycling of the halogen gas used for reacting with the first metal to form the metal halide. In a further embodiment, for example and without limitation, the metal halide (for example, copper chloride or bromide) formed in the reaction is separated from the second metal or alloy (scrap steel), and removed from the reaction chamber via the outlet in the reaction chamber, carried by the carrier gas. The separated metal halide can undergo a separate reaction to covert the separated metal halide to an isolated first metal and reformed halogen gas. In one embodiment, for example and without limitation, the molten salt electrolysis can be used for conversion of the separated metal halide to an isolated first metal and reformed halogen gas. The reformed halogen gas can be recycled back to the reaction chamber for further reaction with first metal.

[0040] In a second aspect in accordance with the specification, disclosed is a system for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the system comprising of:

[0041] heating the first metal and the second metal or alloy to a temperature proximate to the melting point of the first metal and less than the melting point of the second metal or alloy;

[0042] reacting the first metal with a halogen gas to form a metal halide;

[0043] separating the metal halide from the second metal or alloy;

[0044] reacting the metal halide to reform the first metal and the halogen gas; and

[0045] recycling the halogen gas.

[0046] The system disclosed in the second aspect in accordance with the specification includes the steps and process conditions of the first aspect of the process disclosed herein above, along with the step and process conditions of recycling the halogen gas, as described above.

[0047] Figure 1 shows an embodiment of the first aspect and second aspect of the specification, where steel scrap (second metal or alloy) (10) is treated (or pre-treated for purification of steel) for removal of copper (first metal) in a reaction chamber (12). To the reaction chamber (12), steel scrap (10) is charged. The reaction chamber (12) is connected to a halogen gas supply (14) and a carrier gas (not shown). Electrodes (16) are in electrical connection with the steel scrap (10), where direct heat resistance allows the heating the reaction chamber to 400°C-l,300°C, to carry out the reaction of the copper with the halogen gas to form the copper halide, which can be carried with the carrier gas out (20) of the reaction chamber (12) to separate the copper from the steel scrap (10). The separated steel scrap can then be directed to an electric arc furnace (EAF) (18) for further processing and purification. The process of the EAF (18) is not particularly limited and should be known to a person of skill in the art. In an EAF (18), the separated steel can be treated using an electric arc at temperature to achieve a temperature of about l,650°C.

[0048] In a third aspect, the specification relates to a process for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the process comprising the steps of:

[0049] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal;

[0050] exposing the first metal to a gas allowing to form an embrittled first metal; and

[0051] separating the embrittled first metal from the second metal or alloy.

[0052] The step of heating as disclosed herein with respect to the third aspect of the specification involves heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal to form an embrittled first metal. The inventors have uncovered that the heating rate of the scrap metal and the atmosphere selected can have an impact on the level of embrittlement of copper over steel, and hence, affect copper removal from the steel scrap. This characteristic of selective or preferential embrittlement of the first metal over the second metal or alloy using a particular heating rate and / or atmospheric condition, can be utilized when separating a first metal (the impurity) from a second metal or alloy of interest. Hence, by selecting the heating rate and / or atmospheric conditions, preferential embrittlement of copper over steel can be achieved. This is attributed to the preferential reaction of copper over steel. In one embodiment, the reaction leads to preferential oxidation of copper over steel, which allows for ease in separation of the copper from the steel.

[0053] As broadly described above, depending on the composition of the steel scrap containing the copper, the heating rate can be selected to allow for preferential embrittlement of copper over steel, and to minimize reaction with steel. In one embodiment, for example and without limitation, the steel scrap containing the copper, is rapidly heated to attain preferential embrittlement of copper over steel. In a second embodiment, for example and without limitation, the steel scrap is heated at a rate of about 30°C / minute at a minimum. In a third embodiment, for example and without limitation, 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.

[0054] In one embodiment, the scrap steel containing copper is heated to allow for preferential reaction (for example, oxidation) of copper over scrap steel, leading to embrittlement of the copper. It was uncovered that direct heating (as with a gas burner, which impacts the volume of gas and the oxidation state of the gas) or indirect heating (which heats through a barrier and takes a long time to heat up with significant power costs), can lead to alloying of the copper to steel, making it more difficult to remove. By selecting a heating method that avoids alloying of the copper with steel scrap, can lead to embrittlement of the copper, which can be more easily separated. One example, without limitation, of such a method of heating is resistive heating. Another method, for example and without limitation, involves direct resistive heating.

[0055] In a first embodiment, as disclosed herein, the step of heating is carried out using resistance heating, as described herein above. In a second embodiment, as disclosed herein, the step of heating is carried out using direct resistance heating, as described herein above. In a third embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper (first metal) is heated to a temperature of from about 500°C to about l,000°C, and all values and ranges in between. In a fourth embodiment, for example and without limitation, the steel scrap (second metal or alloy) containing the copper (first metal) is heated to a temperature of from about 600°C to about 900°C, and all values and ranges in between. The temperature selected is below the melting point of copper to inhibit alloying of copper to steel.

[0056] The time of heating the scrap steel with copper is not particularly limited, and can be varied depending upon design and application requirements; however, care should be taken to avoid copperalloying to steel, and the heating time should be aligned with the tap-to- tap time in an electric arc furnace (EAF) operation, where the steel is further processed. In one embodiment, for example and without limitation, the heating time for the steel scrap and copper is from about 5 to about 30 minutes, and all values and ranges in between. In a second embodiment, for example and without limitation, the heating time for the steel scrap and copper is from about 10 to about 25 minutes, or about 15 to about 20 minutes, and all values and ranges in between. In a third embodiment, for example and without limitation, the heating time for the steel scrap and copper is for about 30 minutes maximum.

[0057] In one embodiment, the atmosphere of the reaction chamber for carrying out the heating can be controlled to allow for preferential embrittlement of the copper. In a further embodiment, for example and without limitation, the process is carried out in an atmosphere containing one or more of air, enhanced air containing up to 100% oxygen (O2), nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), chlorine (CI2) gas and bromine (Br2) gas. In another further embodiment, for example and without limitation, the partial pressure of the reacting gas, the flow rate, oxygen or halogen supply that leads to embrittlement can be controlled to allow for relative preferential embrittlement of copper of over steel. Controlling the reactive gas as noted above allows for the non-copper (i.e., steel or iron) to not react, react minimally or react less than the ratio of the copper to the steel, and can help with preferential embrittlement of copper over steel. Under such conditions, the reactive gas reacts with copper to a higher degree than steel, or the ratio of copper to steel, and leads to preferential embrittlement of copper over steel.

[0058] The term "embrittlement" as used herein is not particularly limited, and should be known to or understood by a person of skill in the art. In one embodiment, for example and without limitation,embrittlement involves preferential reaction of the oxygen with copper over steel. In a particular embodiment, for example and without limitation, the oxygen can be present in the copper. In another embodiment, for example and without limitation, embrittlement leads to creating a significant decrease of ductility of the copper which allows the copper to become powder on light to moderate agitation and / or milling.

[0059] Various factors come into play for embrittlement of a metal. These factors include heat capacity, gas solubility and thermal conductivity. Based on the differences in these factors for the first metal and the second metal or alloy, conditions of temperature and pressure can be selected to allow for preferential embrittlement of the first metal over the second metal or alloy. Once embrittled, the first metal can be more amenable to separation from the second metal or alloy.

[0060] The step of separating the embrittled first metal and the second metal or alloy is not particularly, and can be varied depending upon design and application requirements. After heating the first metal and second metal or alloy under conditions to embrittle the first metal (for example, copper), the first metal and second metal or alloy can be shaken, agitated, lightly milled or vibrated to separate the first metal from the second metal or alloy.

[0061] An embodiment of the third aspect is further described. In the embodiment, the steel would be heated with direct electricity, either AC or DC, in a sealed unit that can be compressed by electrode plates on either end to ensure contact of the steel scrap throughout the heating time. The heat will be generated by both the materials resistance, and the radiative heat transfer from the material to the reactor surroundings. The steel can be heated to many 100s of degrees rapidly, below the melting point of copper. This promotes embrittlement of the copper during the rapid heat up while maintaining control of the atmosphere and preventing alloying to the steel. The focus for copper removal is the wiresthat are somehow attached to the steel scrap. Larger copper pieces can typically be hand-picked or removed by eddy current. Once heated, the charge would be shaken / vibrated and the smaller embrittled solids would be collected from the bottom of the heater. The hot charge can then be moved to the EAF for melting. The heating chamber can be designed in a way to keep temperature of the steel as required, such as by the use of EAF off-gas as an energy source to maintain the temperature of this chamber.

[0062] The embrittled solids can then be physically separated from the steel while still in the reactor, or immediately after during transport to the EAF. One method to achieve this is by vibration or shaking of the reactor during or after heating. Another way would be the use of vibration during material transport, but heat would need to be retained. Solids would either be collected after transport or collected via openings at the bottom of the chamber.

[0063] The atmosphere can be a combination of air, nitrogen, CO2, and chlorine. The inventors have found that rapid heating of the steel preferentially embrittles copper without significant oxidation of the steel.

[0064] 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 elements.

[0065] The term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and / or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and / or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. It will be understood that any embodiments described as "comprising" certain components may also "consist of" or "consist essentially of," these components, wherein "consisting of" has aclosed-ended or restrictive meaning and "consisting essentially of" means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effects described herein.

[0066] It will be understood that any component defined herein as being included may be explicitly excluded from the claimed invention by way of proviso or negative limitation, such as any specific compounds or method steps, whether implicitly or explicitly defined herein.

[0067] In addition, all ranges given herein include the end of the ranges and also any intermediate range points, whether explicitly stated or not.

[0068] Finally, terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

[0069] The abbreviation, "e.g." is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation "e.g." is synonymous with the term "for example." The word "or" is intended to include "and" unless the context clearly indicates otherwise.

[0070] The phrase "at least one of" is understood to be one or more. The phrase "at least one of...and..." is understood to mean at least one of the elements listed or a combination thereof, if not explicitly listed. For example, "at least one of A, B, and C" is understood to mean A alone or Balone or C alone or a combination of A and B or a combination of A and C or a combination of B and C or a combination of A, B, and C.EXAMPLES

[0071] Example 1: Experimental Setup & Methodology

[0072] To test the effectiveness of copper removal by halogenation, reactive gas experiments were performed. Steel scrap is heated by loading (0.5 wt. % Cu wiring) steel into a crucible, enclosed in a reactor tube. The top of the reactor contained a gas inlet for both air or N2, CO and CO2 (if applicable), and a halogen gas, either CI2 or Br2. Connected to the gas inlet is a gas injection lance to feed gases from the bottom of the sample. An off-gas line is connected to capture reacted solids.

[0073] The steel charge is removed from the reactor after the test is done and melted. A molten sample is taken and analyzed for elemental Cu and Fe content.

[0074] It is worth noting that the furnace used for these experiments heats the steel using indirect resistance heating, whereby electricity is passed through resistive heating coils outside of the reactor tube. The high resistance of these coils turns electricity into heat, transferring heat by radiation to the steel in the reactor tube.

[0075] For this technology, the utilization of a heating method irrespective of carbon use or release is desirable. Passing electricity through the steel can heat sufficiently as to melt the copper. However, the use of electrical heating in any capacity (i.e. direct or indirect resistance heating, or another form of heat generation which does not use carbon as fuel) is one embodiment for the technology.

[0076] Results

[0077] Table 1 provides a summary of all test conditions and resulting copper removal as a percent. The different variables listed include the type of atmosphere (i.e., inert or oxidizing), halogen to copper ratio (mole basis) and test duration. The operating conditions varied in these tests are listed below:

[0078] Halogen: Cl2or Br2

[0079] Cu Content: 0.5 wt. %

[0080] Stoichiometric ratio of halogen to copper: 1: 1 to 3: 1

[0081] Carrier gas to halogen ratio: 10: 1, 20: 1

[0082] Residence time: 15-30 minutes

[0083] Temperature: 1050-1200°C , although the selective melting window for Cu exists between ~1100-1500°C

[0084] CO:CO2ratio: 10%Table 1: Summary of test conditions and resulting copper removal for completed chlorination and bromination tests.* denotes test without the use of halogen (just air).*** denotes test was run below the melting point of copper, 1050°C

[0085] Results from Table 1 show removal of copper with the use of a halogen gas. In addition, an inert atmosphere (nitrogen) and use of chlorine was able to significantly remove copper from steel scrap.

[0086] Example 2:

[0087] Metal charges consisting of copper and steel wire of various thicknesses were prepared for heating experiments. The wires, between 8-18 AWG in thickness, were compressed vertically between two stainless steel rods welded to steel plates - each rod connected to a power supply by copper leads. These steel plates, with metal sample between them, were sealed in an insulated ceramic reactor (effective for bench-scale testing, although commercial reactor construction would be of a different material). Multiple gas inlet lines were setup at the bottom of the vertical reactor, to allow for maximum residence time of the gas and enhanced gas / solid contact.

[0088] Once the power supply was turned on, gas flow was turned on for the specified time. The metal charge was heated in the timeframe of 10-30 minutes and reached internal reactor temperatures of 500-1000°C from room temperature. An input voltage of 1-8 V and current of 0-300 A was used (adequate for charge sizes in the hundreds of grams - much higher power would be required for charge sizes in the tonnage scale).

[0089] Once cooled, the metal was removed from the reactor. The characterization of the embrittlement effect from the invention was done by shaking and / or milling to break apart brittle copper from the steel and collect by gravity.

[0090] The following are examples of test conditions.

[0091] Heating of steel in the hundred-gram range to 500-800°C in an oxidizing atmosphere over 30 minutes, where air is flowed at 200 mL / min starting at room temperature, and the embrittlement of copper from rapid heating and oxidation is assessed after the test duration.

[0092] Heating of steel in the hundred-gram range to 500-800°C in an inert atmosphere over 30 minutes, where N2 is flowed at 200 mL / min starting at room temperature, and the embrittlement of copper from rapid heating without oxidation is assessed after the test duration.CLAUSES

[0093] 1. A process for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the process comprising the steps of:

[0094] heating the first metal and the second metal or alloy to a temperature proximate to the melting point of the first metal and less than the melting point of the second metal or alloy;

[0095] reacting the first metal with a halogen gas to form a metal halide; and

[0096] separating the metal halide from the second metal or alloy.

[0097] 2. The process of clause 1, wherein electrical heating is carried out to heat the first metal and the second metal or alloy.

[0098] 3. The process of clause 1 or 2, wherein the electrical heating is carried out by direct resistance heating.

[0099] 4. The process according to any one of clauses 1 to 3, wherein the first metal is copper.

[0100] 5. The process according to any one of clauses 1 to 4, wherein the second metal or alloy is steel.

[0101] 6. The process according to any one of clauses 1 to 5, wherein the step of heating is carried out to a temperature of from about 900°C to about 1500°C.

[0102] 7. The process according to any one of clauses 1 to 5, wherein the step of heating is carried out to a temperature of from about 1000°C to about 1200°C.

[0103] 8. The process according to any one of clauses 1 to 7, wherein the halogen gas is chlorine gas or bromine gas.

[0104] 9. The process according to any one of clauses 1 to 8, wherein the metal halide formed is in a gas phase, and the second metal or alloy is in a solid phase, the process further comprising the step of removal of the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

[0105] 10. The process according to any one of clauses 1 to 9, wherein after separation of the metal halide, further comprising the step of reacting the metal halide to isolate the first metal from the second metal or alloy, and reform the halogen gas.

[0106] 11. The process according to clause 10, further comprising the step of recycling the halogen gas.

[0107] 12. The process according to any one of clauses 1 to 11, wherein the ratio of the halogen gas to the first metal is from about 1: 1 to about 10: 1.

[0108] 13. The process according to any one of clauses 1 to 11, wherein the ratio of the halogen gas to the first metal is from about 1: 1 to about 3: 1.

[0109] 14. The process according to any one of clauses 1 to 13, further comprising a carrier gas.

[0110] 15. The process according to clause 14, wherein the carrier gas is air or nitrogen.

[0111] 16. The process according to clause 14 or 15, wherein the ratio of the carrier gas to the halogen gas is from about 5: 1 to about 100: 1.

[0112] 17. The process according to any one of clauses 1 to 16, wherein the halogen gas has a residence time of from 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.

[0113] 18. A system for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the system comprising of:

[0114] heating the first metal and the second metal or alloy to a temperature proximate to the melting point of the first metal and less than the melting point of the second metal or alloy;

[0115] reacting the first metal with a halogen gas to form a metal halide;

[0116] separating the metal halide from the second metal or alloy;

[0117] reacting the metal halide to reform the first metal and the halogen gas; and

[0118] recycling the halogen gas.

[0119] 19. The system of clause 18, wherein electrical heating is carried out to heat the first metal and the second metal or alloy.

[0120] 20. The system of clause 18 or 19, wherein the electrical heating is carried out by direct resistance heating.

[0121] 21. The system according to any one of clauses 18 to 20, wherein the first metal is copper.

[0122] 22. The system according to any one of clauses 18 to 21, wherein the second metal or alloy is steel.

[0123] 23. The system according to any one of clauses 18 to 22, wherein the step of heating is carried out to a temperature of from about 900°C to about 1400°C.

[0124] 24. The system according to any one of clauses 18 to 23, wherein the step of heating is carried out to a temperature of from about 1000°C to about 1200°C.

[0125] 25. The system according to any one of clauses 18 to 24, wherein the halogen gas is chlorine gas or bromine gas.

[0126] 26. The system according to any one of clauses 18 to 25, wherein the metal halide formed is in a gas phase, and the second metal or alloy is in a solid phase.

[0127] 27. The system according to any one of clauses 18 to 26, wherein the ratio of the halogen gas to the first metal is from about 1: 1 to about 10: 1.

[0128] 28. The system according to any one of clauses 18 to 27 , wherein the ratio of the halogen gas to the first metal is from about 1: 1 to about 3: 1.

[0129] 29. The system according to any one of clauses 18 to 28, further comprising a carrier gas.

[0130] 30. The system according to clause 29, wherein the carrier gas is air or nitrogen.

[0131] 31. The system according to clause 29 or 30, wherein the ratio of the carrier gas to the halogen gas is from about 5: 1 to about 100: 1.

[0132] 32. The system according to any one of clauses 18 to 31, wherein the halogen gas has a residence time of from 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.

[0133] 33. A process for separation of a first metal from a second metal or alloy, the process comprising the steps of:

[0134] heating the first metal and the second metal or alloy to a temperature below the melting point of the first metal;

[0135] exposing the first metal to a gas to form an embrittled first metal; and

[0136] separating the embrittled first metal from the second metal or alloy.

[0137] 34. The process of clause 33, wherein electrical heating is carried out to heat the first metal and the second metal or alloy.

[0138] 35. The process of clause 33 or 34, wherein direct resistance heating is used to carry out the heating step.

[0139] 36. The process according to any one of clauses 33 to 35, wherein the heating step has a minimum heating rate of about 30°C / minute.

[0140] 37. The process according to any one of clauses 33 to 36, wherein the heating step is carried out from about 5 to about 30 minutes.

[0141] 38. The process according to any one of clauses 33 to 37, wherein the process is carried out in an atmosphere containing one or more of air, enhanced air containing up to 100% oxygen, nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), chlorine (CI2) gas and bromine (Br2) gas.

[0142] 39. The process according to any one of clauses 33 to 38, wherein the first metal is copper.

[0143] 40. The process according to any one of clauses 33 to 39, wherein the second metal or alloy is steel.

[0144] 41. The process according to any one of clauses 33 to 40, wherein the step of heating is carried out to a temperature of from about 500°C to about 1000°C.

[0145] 42. The process according to any one of clauses 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, the process further comprising the step of removal of the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

[0146] 43. The process according to clause 42, wherein after separation of the metal halide, further comprising the step of reacting the metal halide to isolate the first metal from the second metal or alloy, and reform the chlorine or bromine gas.

[0147] 44. The process according to clause 43, further comprising the step of recycling the chlorine or bromine gas.

[0148] 45. The process according to any one of clauses 33 to 44, wherein the first metal and second metal or alloy is attrited for separation of the first metal from the second metal or alloy.

[0149] 46. The process according to any one of clauses 33 to 45, wherein shaking, milling or trolling is carried out to separate the first metal from the second metal.

[0150] 47. A process for preparation of steel, comprising the process as defined in any one of clauses 1 to 47.

[0151] 48. The process of clause 47, further comprising the step of directing the separated second metal or alloy to an electric arc furnace.

[0152] The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the Examples. These Examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the illustrative examples, make and utilize the constructs of the present invention and practice the claimed methods. The working examples therefore, specifically point out the typical aspects of the present invention and are not to be construed as limiting in any way in the remainder of the disclosure. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation.

[0153] 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.

[0154] Although preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims. Therefore, the above discussed embodiments are considered to be illustrative and not restrictive.

Claims

WHAT IS CLAIMED IS:

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

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

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

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

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

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

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

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

9. The process according to 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, the process further comprising the step of removal of the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

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

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

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

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

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

16. The process according to 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. The process according to any one of claims 1 to 16, wherein the halogen gas has a residence time of from 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. A system for separation of a first metal from a second metal or alloy, wherein the first metal has a melting point below a melting point of the second metal or alloy, the system comprising of: heating the first metal and the second metal or alloy to a temperature proximate to 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 reform the first metal and the halogen gas; andrecycling the halogen gas.

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

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

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

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

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

24. The system according to any one of claims 18 to 23, wherein the step of heating is carried out to a temperature of from 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. The system according to any one of claims 18 to 25, wherein themetal halide formed is in a gas phase, and the second metal or alloy is in a solid phase.

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

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

31. The system according to 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. The system according to any one of claims 18 to 31, wherein the halogen gas has a residence time of from 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. A process for separation of a first metal from a second metal or alloy, the process comprising the steps of: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 embrittled first metal; and separating the embrittled first metal from the second metal or alloy.

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

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

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

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

38. The process according to any one of claims 33 to 37, wherein the process is carried out in an atmosphere containing one or more of air, enhanced air containing up to 100% oxygen, nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), chlorine (CI2) gas and bromine (Br2) gas.

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

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

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

42. The process according to 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, the process further comprising the step of removal of the gas phase containing the metal halide to separate the metal halide from the second metal or alloy.

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

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

45. The process according to any one of claims 33 to 44, wherein the first metal and second metal or alloy is attrited for separation of the first metal from the second metal or alloy.

46. The process according to any one of claims 33 to 45, wherein shaking, milling or trolling is carried out to separate the first metal from the second metal.

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

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

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