OXIDATIVE CALCINATION OF BLACK SLAG AND SALT CAKE

Abstract

The components of salt from the granules can be efficiently extracted through evaporation. During the treatment of the granules, temperatures can be allowed to approach or exceed the boiling point of one or more of the salt components, preferably in an oxidizing medium. The temperature can be maintained high enough so that the salt content exerts an appreciable vapor pressure and can be sustained for a sufficient time to allow most, all, or substantially all of the salt content to evaporate and be carried away from the furnace in the combustion gases. The evaporated salt can then be condensed and collected.

Description

This application claims the benefit and priority of United States Provisional Application No. 62 / 867,721, filed on June 27, 2019, and entitled “OXIDATIVE CALCINATION OF BLACK GRASS AND SALINE SLAG,” the contents of which are incorporated herein by reference in their entirety for all purposes. TECHNICAL FIELD This description generally relates to the recycling of metals and more specifically to the treatment and use of granules for the recycling of aluminum. BACKGROUND The byproducts of metal recycling, and specifically aluminum recycling, can be difficult to handle and process. For example, aluminum recycling typically produces black or white granules as a byproduct of the recycling process. Black granules generally contain some aluminum, a moderate amount of aluminum oxides, and a substantial proportion of salts. For example, some black granules resulting from the recycling of used beverage can stock (UBC) produce granules that are approximately 10% aluminum, 50% salts, and 40% oxides, although other amounts may be present. White granules are a mixture of aluminum oxides and metallic aluminum and typically contain very little salt. The metal in white granules is most often recovered by treating the granules with salts at high temperatures. This results in an oxide / salt byproduct commonly referred to as salt slag.These byproducts may contain nitrides, carbides, and other materials. Byproducts can be hazardous and may require highly controlled transport and disposal operations. For example, aluminum pellets from recycling can generate explosive hydrogen when wet and must therefore be handled carefully. Current pellet treatment technologies generally require separate facilities, so the pellets must be transported from their generation site to a treatment facility. In some countries, regulations prohibit various handling and disposal methods for such materials. Current pellet treatment technologies focus on metal recovery (e.g., from aluminum) through heating and melting, and salt recovery through leaching and evaporation.These current technologies rely on high energy production, such as heating batches of white pellets to remove the metal, and on the use of large quantities of water and energy to leach salt from the pellets or salt slag and evaporate that water to recover the salt. The water and energy used to leach salt from the pellets is significant enough that some current white pellet treatment techniques specifically focus on a salt-free process to avoid having to recover the salt in a subsequent step. Furthermore, the salt leached from the pellets can generate substantially harmful, toxic, and / or reactive gases (e.g., H₂S, PH₃, NH₃, H₂CH₄), which require controlled collection and destruction. Thus, there is a desire for improved handling and treatment of aluminum recycling granules, so that the components of the granules can be recovered more easily and efficiently, and so that the granules can be handled more easily and efficiently. SUMMARY The term "modality" and similar terms are intended to refer broadly to all the subject matter of this description and the following claims. Statements containing these terms should be understood as not limiting the subject matter described herein or limiting the meaning or scope of the following claims. The modalities of the description covered herein are defined by the following claims, not by this summary. This summary is a high-level overview of several aspects of the description and introduces some of the concepts further described in the Detailed Description section below. This summary is not intended to identify the key or essential characteristics of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter.The subject matter shall be understood by reference to the appropriate portions of the entire specification of this description, any or all of the drawings and each claim. In several examples, a method is provided for extracting salt from a metal recycling byproduct. The method may include loading a container with the granules. The granules may consist of aluminum oxides and salt. The method may further include heating the granules to a temperature at or above the boiling point of the salt. The method may further include maintaining the granules at this temperature to allow the salt to evaporate as salt vapor. The method may further include directing the salt vapor out of the container through a gas outlet. The method may further include capturing the salt vapor. In several examples, a system is provided for extracting salt from a metal recycling byproduct. The system may include a container to receive the granules. The granules may consist of aluminum oxides and salt. The system may also include a heat source attached to the container to heat the granules to a temperature high enough to evaporate the salt as salt vapor (e.g., 1200°C or higher). The system may also include a gas outlet attached to the container to transport the gas and salt vapor from the container. Finally, the system may include a salt collector attached to the gas outlet to collect and condense the salt vapor. Several implementations described herein may include additional systems, methods, features, and advantages, which may not necessarily be expressly described herein, but which will be apparent to a person of ordinary skill in the art upon examination of the following detailed description and accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within this description and protected by the accompanying claims. iviA / a / zuz ι / u 1 o / u 1 BRIEF DESCRIPTION OF THE DRAWINGS The specification refers to the following attached Figures, in which the use of similar reference numbers in the different Figures is intended to illustrate similar or analogous components. Figure 1 is a schematic diagram of a thermal processing system for granules, according to certain aspects of the present description. Figure 2 is a schematic diagram of a granulation system for granules, according to certain aspects of the present description. Figure 3 is a schematic diagram of a granule of the granules being heated, according to certain aspects of the present description. Figure 4 is a flow diagram that describes a process for generating granules from the granules, according to certain aspects of the present description. Figure 5 is a flow diagram that describes a process for processing granules from granules, according to certain aspects of the present description. Figure 6 is a schematic diagram describing a system for extracting salt from the granules, in accordance with certain aspects of the present description. Figure 6A is a schematic diagram describing another system for extracting salt from the chaff, in accordance with certain aspects of the present description. Figure 7 is a flow diagram that describes a process for extracting salt from granules, in accordance with certain aspects of the present description. Figure 8 is a schematic diagram describing a two-stage process for heat-treating granules, in accordance with certain aspects of the present description. Figure 9 is a schematic diagram describing a two-stage, single-container process for heat-treating granules, in accordance with certain aspects of the present description. DETAILED DESCRIPTION Certain aspects and features of this description relate to techniques for extracting and capturing salt during the treatment of coarse salt. During coarse salt treatment, temperatures may be allowed to exceed the boiling point of one or more components of the salt in the coarse salt, preferably in an oxidizing medium. The temperature may be maintained high enough for the salt content to exert an appreciable vapor pressure and may be sustained for a sufficient time to allow most, all, or substantially all of the salt content to evaporate, leaving behind the non-volatile components of the coarse salt. The evaporated salt may then be condensed and collected. The recycling of metals, such as aluminum, can result in a secondary metal (e.g., secondary aluminum) and various recycling byproducts. For example, in aluminum recycling processes, the recycling byproducts can be types of granules, or mixtures of metallic aluminum and aluminum oxides. In some cases, other materials in the aluminum being recycled may include contaminants and salts, which can end up in the granules. There can be different types of granules, such as white granules and IVIA / a / ¿U¿ l / UID / UI black granules. White granules consist primarily of aluminum and aluminum oxides, while black granules additionally contain salts. The terms white and black, when used with respect to granules, refer to a type of granule, and not necessarily to the physical color of the granules. In some cases, the processing of white granules may include combining the white granules with salts to facilitate the extraction of the secondary metal. Black granules are a common byproduct of recycling used beverage can stock (UBC), in which approximately 2% by weight of salt is used to remove impurities and oxides from the aluminum in the UBC stock. The recycling processes for UBC stock result in black granules or lumps that vary in size, on the order of tenths of a millimeter (e.g., 25 mm) in diameter. These black granules typically contain approximately 10% aluminum, 50% salt, and 40% additional oxides and contaminants by weight. White granules are a common byproduct of many types of aluminum recycling processes. White granules can contain a substantial amount of aluminum that can be removed through further processing by contacting the white granules with salt to generate salt slag. As used herein, the general term "granules" is inclusive of the salt slag generated by combining white granules with salt. It has been found, as with UBC recycling, that black granules in their native form can retain up to approximately 4% carbon by weight, even after heat treatment. Generally, heat treatment of native black granules can form a layered ball, where the outermost layers are coated with complex oxides and the innermost layers contain unoxidized carbon and other compounds. It was determined that a larger surface area to volume ratio may be desirable to ensure that more of the residual carbon in the black granules reacts with oxygen. Crushing black salt granules before heat treatment can be potentially problematic, at least in part because the fine particles of the black salt granules are difficult to handle and can be carried over in the gas produced from the reaction vessel (e.g., rotary kiln). In cases where the salt vapor is collected from the reaction vessel, as described herein, the fine particles of the black salt granules can be carried over in the produced gas, potentially contaminating the salt vapor. To avoid the problem with fine particles in black salt granules, the disintegrated black salt granules (e.g., disintegrated through crushing or any other suitable technique) can be agglomerated into granules. In some cases, the granules can be shaped to achieve the desired thermal processing. For example, the granules can have through channels, through which oxygen can pass and out of which salt vapor can escape. In some cases, a channel can pass through the granule, although this need not always be the case. In some cases, a channel can be one-ended and can extend from one surface of the granule partially into the granule. The granules can be formed through granulation, compaction, or any other agglomeration technique. In some cases, the granules can be formed using techniques that create inherent channels.In some cases, the fine particles of black granules may be mixed with additives prior to agglomeration, so that the additives form channel precursors within the granules. Upon oxidation, the additives may decompose, leaving voids that form or expose the channels in the granules. The additives may be selected to oxidize, volatilize, or otherwise decompose at sufficiently low temperatures so that the channels are exposed by the time the thermal processing temperatures for black granule processing are reached. For example, additives may be selected that oxidize at or below approximately 500°C, 600°C, 700°C, or 800°C, or between approximately 500°C and 800°C. The temperature at which the additive oxidizes, volatilizes, or otherwise decomposes, and exposes the channels, may be referred to as a channel exposure temperature.The granules thus comprise channels when heated to temperatures at or above the channel exposure temperature. For example, a granule may comprise channels when heated to temperatures at or above 800°C for additives that oxidize at or below 800°C, including additives that oxidize at or below 500°C. In some cases, the disintegrated black granules may form fine particles with diameters of, or less than, approximately 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, or 2 mm at one end of the upper range, and diameters of, or greater than, approximately 50 micrometers, 40 micrometers, 30 micrometers, 20 micrometers, 10 micrometers, or 5 micrometers at one end of the lower range. In some cases, an eddy current separator may be used to remove excess metallic aluminum from the fine black granule particles. In some cases, the fine black granule particles may be screened to remove oversized particles, which may then be diverted again for further disintegration or fed into the feed for thermal processing. In some cases, the agglomeration process can result in black granules of consistent sizes, such as granules with diameters (e.g., maximum granule diameter or average granule diameter) between 5 mm and 50 mm, between 10 mm and 50 mm, between 10 and 40 mm, between 10 and 30 mm, between 10 and 20 mm, between 12 mm and 18 mm, or between 14 mm and 16 mm. In some cases, the variation among granules may be approximately 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm. The consistent granule size can facilitate the accurate estimation of processing times for thermal processing. In some cases, additives may include waste materials from other industries. For example, additives may include one or more types of automotive shredding sludge, post-consumer waste (e.g., shredded plastic bottles or agricultural byproducts such as corn silk, wheat hulls, straw, or rice husks), textile waste, carpet waste, UBC dust reclaimer, or other such products. In some cases, additives may be selected to provide a certain degree of permeability to a pellet at an elevated temperature (e.g., 500°C or above). In some cases, additives may also include fuel additives selected to provide fuel to help generate heat within the reaction vessel.In some cases, an additive may be selected to provide fuel, and also to improve the permeability of a granule at elevated temperature. In some cases, the agglomerated granules may be generally spheroid in shape, although this is not necessarily the case, and other regular or irregular shapes may be used. In some cases, the granules may have a smooth or rough surface. In some cases, the granules may be further preprocessed to alter their physical shape, thereby facilitating their permeability to gases. In some cases, black salt granules adapted as described herein can improve the efficiency and speed of salt extraction. In some cases, black salt granules adapted as described herein can also improve the oxidation of residual carbon, residual metallic aluminum, and / or other residual compounds. In some cases, black salt granules can be used in conjunction with a reaction vessel designed to maintain an oxidative environment. In some cases, salt can be extracted from salt-containing granules through thermal processing. Traditionally, the thermal processing of granules is carried out at temperatures well below 1200°C. However, by allowing or encouraging the reaction vessel to reach temperatures of or above 1200°C, the salt can evaporate as salt vapor and be directed out of the reaction chamber, such as through a gas outlet. In some cases, the reaction vessel is allowed or encouraged to reach a temperature of or above the boiling points of the salts within the granules (e.g., 1416°C for KCl or 1450°C for NaCl) to increase the rate at which the salt evaporates as salt vapor and is directed out of the reaction chamber. In some cases, the gas outlet can also function as a material inlet.Although a reaction vessel may be able to withstand temperatures in the range of 1200°C to 1600°C, these temperature ranges were not previously used in the aluminum industry. The granules can be held at these high temperatures until approximately 95%, 99%, 99.9%, or another relevant amount of the salt in the granules has evaporated. In some cases, the granules can be kept at these high temperatures for approximately 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 140 minutes, 145 minutes, or 150 minutes.In some cases, such as with small, permeable granules, the granules can be maintained at these high temperatures for approximately 10, 15, 20, 25, or 30 minutes. In some cases, the use of granulated granules can facilitate the oxidation of residual compounds within the granules, making it easier to reach and / or maintain these high temperatures simply by adding oxygen to the reaction vessel (for example, without applying heat to the reaction vessel from a separate heat source, such as an oxyfuel burner). The salt vapor coming out of the reaction vessel can be collected and condensed into the salt, which can be collected and optionally reused for further treatment of the granules (e.g., white granules) or UBC (e.g., in a side-pit furnace). In some cases, maintaining the high temperatures necessary to extract salt from the granules via evaporation results in the unexpected formation of a continuous, dense oxide layer that adheres to the refractory inner surface of the reaction vessel. Although this oxide layer can be periodically removed (for example, to prevent loss of reactor volume), its presence can provide a degree of protection to the underlying refractory lining from abrasive wear, thermal shock, and chemical attack, thus extending the life of the reaction vessel. Surprisingly, maintaining these high temperatures also results in the removal of aluminum nitrides, thereby enabling more efficient recycling of certain granules or granule treatment processes that contain relatively high amounts of aluminum nitride.In some cases, a two-stage treatment process for the granules may be carried out. In the first stage, the white granules are contacted with salt at a specific temperature to recover the metal, with the resulting salt slag being a byproduct. In the second stage, the salt slag may be thermally processed at a second temperature (for example, at a temperature high enough to evaporate the salt, in some cases at or above the boiling point of salt) to evaporate the salt as salt vapor for collection and condensation into salt. In some cases, the salt vapor and / or salt may be temporarily stored and reused in the subsequent treatment of additional white granules. In some cases, increased quantities of salt may be obtained by mixing existing black granules with the white granules and / or salt slag before the second stage.In some cases, the second stage may include oxidizing residual compounds in the granules, such as remaining metal. In some cases, each stage of the two-stage granule treatment process can occur in the same container, although this is not always the case. When a single container is used, the residual heat remaining after the removal of inert oxides in the second stage can be used to begin heating the new white granules in a subsequent treatment process. Thus, the two-stage granule treatment process can involve the reuse of salt and thermal energy between the second stage of one treatment process and the first stage of a subsequent treatment process. In some cases, the two-stage granulation process can facilitate the recycling of lower-grade waste (e.g., thermal break material). In such cases, the white granules supplied to the reaction vessel come from the melting of the waste within the reaction vessel. The waste can be melted, secondary aluminum can be derived, salt can be added to produce salt slag, additional secondary aluminum can be derived, and heat and oxygen can be increased to evaporate the salt and generate the inert oxide residue. In some cases, additional rich organic material may be added to provide some of the energy required to reach the high temperatures in the second stage of the two-stage pellet treatment process. These illustrative examples are provided to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the concepts described. The following sections describe various additional features and examples with reference to the drawings, in which similar numbers indicate similar elements, and directional descriptions are used to describe the illustrative modalities, but as iviA / a / zuz ι / u io / ui in the illustrative modalities, they should not be used to limit the present description. The elements included in the illustrations herein may not be drawn to scale. Figure 1 is a schematic diagram of a thermal processing system for granules 100 according to certain aspects of the present description. The system 100 may comprise a reaction vessel 102 in which the thermal processing of the granules may take place. The reaction vessel 102 may be a rotary kiln, although any other suitable reaction vessel may be used. A source of granules 104 may be used to supply the reaction vessel 102 with the granules (e.g., white granules, black granules, or salt slag). The reaction vessel 102 may be supplied with initial heat from a heat source 106, such as an oxyfuel burner.When thermal processing is taking place, heat can be increased and / or maintained within the reaction vessel 102, through the addition of oxygen, such as through an optional oxygen inlet 107 or the heat source 106 (for example, when the heat source 106 is used in a non-heating manner to provide oxygen to the reaction vessel 102). In some cases, a controller 114 can be coupled to the heat source 106 and / or the oxygen inlet 107, to control the temperature inside the reaction vessel 102. The controller 114 can be coupled to a temperature sensor positioned to read the temperature inside the reaction vessel 102. During heat treatment, combustion gases can be expelled from the reaction vessel 102 via a gas outlet 108. In some cases, the gas outlet 108 can be an opening in the reaction vessel 102, through which pellets are supplied to the reaction vessel 102. In some cases, an optional salt source 112 may supply salt to reaction vessel 102, such as in the processing of white granules. Generally, salt can be recovered from black salt slag and salt dross by dissolving the salt in water, removing the insoluble solids from the salt, and then evaporating the water to recover the salt. However, when using this process, the salt may contain occluded water (e.g., small pockets of water that are physically / mechanically trapped within the salt crystals during evaporation and drying). When salt containing occluded water is heated rapidly (e.g., by depositing the salt onto the surface of molten aluminum), the trapped moisture generates pressure that can cause decrepitation (e.g., the salt crackles or pops). In some cases, a salt collector 110 can be attached to the gas outlet 108 to receive the salt vapor and collect the salt from the salt vapor (e.g., through condensation of the salt vapor).In some cases, the salt collector 110 can be coupled to the salt source 112 to replenish the salt source 112 by extracting salt from the granules within the reaction vessel 102. The salt collected by the salt collector 110 may not contain occluded water and can be heated rapidly without causing decrepitation. Using the salt collector 110 to replenish the salt source 112 allows for faster salt processing because no additional steps are required to prevent decrepitation. In some cases, an optional sensor 116 (e.g., an optical sensor) can be coupled to the salt collector 110 and / or the gas outlet 108 to detect the salt concentration in the salt vapor (e.g., by optically inspecting the opacity of the salt vapor). The sensor 116 can be coupled to the controller 114 to provide feedback for controlling the temperature of the reaction vessel 102 in response to changes in the salt concentration in the salt vapor. For example, once the salt concentration in the salt vapor falls below a threshold, a determination can be made that at least 95%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8% or 99.9%, or some other relevant amount of salt has been extracted from the granules, inside the reaction vessel 102, and the controller 114 can control the heat source 106 and / or the oxygen inlet 107 to reduce the temperature inside the reaction vessel 102. Although System 100 can be used with any suitable metal, System 100 can be used advantageously with aluminum recycled granules. Figure 2 is a schematic diagram of a granulation system for granules 200, according to certain aspects of the present description. The granules 218 pieces may be spherical or otherwise shaped and may contain oxides (e.g., aluminum oxides) and other materials, such as metal (e.g., metallic aluminum) and salt. The granules 218 pieces may be of inconsistent sizes, such as sizes ranging from 10 mm in diameter to 50 mm in diameter, although pieces of other sizes may be present. The granules 218 pieces may be fed into a granule crusher 220, which can crush the granules 218 pieces into granule particles 222 (e.g., fine granule particles). The particles of the 222 granules can have diameters of, or less than, 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm or 1 mm.The granules 222 can be mixed with additives from an additive supply 224 and then introduced into an agglomerator 526. The agglomerator 526 can be a granulator or other suitable device for converting the granules 222 and the additives into granules 228. The granules 228 can be of a relatively uniform size on the order of 10 mm to 20 mm in diameter. In some cases, the granulator can be an extrusion granulator designed to produce extruded granules that are oblong or elongated. As used herein, the reference to a diameter of an oblong or elongated shape can refer to a maximum or average diameter of a cross-section of an oblong or elongated shape, or to a maximum or average length of an oblong or elongated shape. In some cases, the granules may have a length-to-diameter ratio of 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0. The proportions of the additives and the granules 222 particles can be controlled to achieve a desired permeability of the resulting granules 228, after heating the granules 228 to a channel exposure temperature (e.g., a temperature at which the additive oxidizes and exposes the channels within the granules 228). Figure 3 is a schematic diagram of a granule of granule 328 being heated, in accordance with certain aspects of the present description. The granule of granule 328 may be a granule of granule 228 of Figure 2. The granule of granule 328 may comprise granules imbued with additives. The additives may establish the precursors of channel 330 within the granule 328. After heating granule 328 to a channel exposure temperature for a sufficient amount of time, the additives may oxidize, volatilize, or otherwise decompose. The channeled granule iviA / a / ¿u¿ ι / u io / ui The resulting 332 may contain channels 334 running through it. The channels 334 may pass through the grooved granule 332 in any direction, although in some cases, a channel 334 may extend less than halfway through the grooved granule 332 (for example, to achieve a one-ended channel 334). In some cases, the channels 334 may be surrounded by the granule material of the grooved granule 332 (for example, forming a gap through the grooved granule 332). In some cases, however, the channels 334 may be formed entirely on the surface of the grooved granule 332, such as in the form of valleys on the surface. The channels 334 in the grooved granule 332 can effectively increase the surface area to volume ratio of the granule, can allow oxygen to permeate more effectively into the granule, and can allow salt vapor to escape more effectively from the granule. Figure 4 is a flow diagram describing a process 400 for generating the granules from the pellets, in accordance with certain aspects of this description. Process 400 can be used to generate the granules from pellet 228 or the granules from pellet 328 of Figures 2 or 3, respectively. In block 402, the granule pieces can be received. In block 404, the granule pieces can be disintegrated. Disintegration can be achieved by crushing, grinding, or otherwise interacting with the granule pieces to reduce the size to granule particles having diameters of, or less than, 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2 mm, or 1 mm. In the optional 406 block, metallic aluminum can be extracted from the granule particles (e.g., disintegrated or crushed granule pieces), using an eddy current separator. In the optional block 408, the granule particles can be screened for size. Screening the granule particles may include separating oversized particles. In some cases, the oversized particles may be directed back to block 404 for further disintegration. In some cases, the oversized particles may be fed into block 412 for thermal processing. In block 410, the granule particles can be agglomerated (e.g., reconstituted) into pellets. Agglomeration of the granule particles into pellets can occur through granulation, compaction, or any other suitable pellet-forming technique. In some cases, additives can be provided in block 414 and used during agglomeration in block 410 to generate a pellet consisting of granule particles and additives. The quantity and / or type of additives can be controlled to achieve a desired permeability of the resulting pellet. In block 412, the granules from the granules may be thermally processed. Thermal processing of granules from the granules may include heating them to extract a compound, such as a metal or a salt. In some cases, thermal processing in block 412 may include only granules agglomerated in block 410. In some cases, thermal processing in block 412 may additionally or alternatively include oversized particles fed from screening in block 408.For example, at least some of the oversized particles fed in may be large enough to avoid becoming airborne fine particles, which could contaminate an exhaust stream during the thermal processing in block 412 and / or may be small enough to facilitate extraction through thermal processing in block 412, without undergoing an intermediate operation in blocks 410 and / or 412, which relate to agglomeration with other granules and / or additives. Figure 5 is a flow diagram describing a process 500 for processing pellets, according to certain aspects of the present description. In block 502, the pellets may be received. The pellets may contain additives in the form of channel precursors. In block 504, the pellets may be heated to or above a channel exposure temperature. In some cases, the channel exposure temperature is 500°C, 700°C, 600°C, or 500°C, or between 500°C and 800°C. Heating the pellets in block 504 can cause the additives in the pellets to oxidize, volatilize, or otherwise break down, thereby exposing the channels within the pellets.In block 506, the granules of the granules may continue to be heated for thermal processing. In some cases, the thermal processing of the granules in block 506 may include evaporating the salt from the granules in block 508. In some cases, the evaporation of salt from the granules in block 508 may include passing the salt vapors out of the granule channels. Figure 6 is a schematic diagram describing a system 600 for extracting salt 650 from granules 628, according to certain aspects of the present description. The granules 628 may be granules from granules 228 or granules from granules 328 of Figures 2 or 3, respectively. The system 600 may include a reaction vessel 602. The reaction vessel 602 may be the reaction vessel 102 of Figure 1. The granules 628 (e.g., black granules or salt slag) can be introduced into the reaction vessel 602 via a feed chute 640. A heat supply 606 can provide hot gas and optionally oxygen to the reaction vessel 602 during the treatment process. In some cases, the reaction vessel 602 can be rotated to turn over the granules 628. After heating to a sufficient temperature (e.g., a temperature approaching the boiling point of the salt, and in some cases, a temperature at or above the boiling point of the salt), the salt within the granules 628 can evaporate as salt vapor 636. The gases within the reaction chamber 602 can flow in the direction 638, carrying the vapor from salt 636 out of the gas outlet 608. The vapor from salt 636 can be captured in a salt collector 610. The salt collector 610 can include a hood 642 for collecting the vapors from salt 636, a condenser 644 for condensing the vapor from salt 636 into salt 650, and a salt collection chamber 646 for storing the regenerated salt 650. In some cases, condensation of the salt vapor can be achieved or facilitated by introducing air and / or water into the salt collector 610 (e.g., water spray), such as through an inlet 643 coupled with, or included in, the condenser 644. In some cases, an optional supply path 648 can redirect the regenerated salt 650 back to the reaction chamber 602 (e.g., via the feed trough 640).In some cases, the salt collector 610 may include an additional outlet 652 to remove gases other than salt vapors 636. Figure 6A is a schematic diagram describing another system 600A for extracting salt 650 from the granules, in accordance with certain aspects of the present description. The system 600A shown in Figure 6A may include elements already described with respect to the system 600 shown in Figure 6. The system 600A shown in Figure 6A differs from the system 600 shown in Figure 6 with respect to the salt collector 610A. In the salt collector 610A, the salt vapor 636 collected by the hood 642 can be converted to a liquid salt mist 641 by mixing it with water and / or air introduced through a water and / or air inlet 643. A bed of anti-fog medium 645 can be placed in the path of the liquid salt mist 641, and can induce condensation or otherwise cause the liquid salt mist 641 to coalesce into droplets 647, which can fall and be collected as a liquid salt bath within a tank 649.A suitable option for the antifog medium 645 may be tabular alumina spheres, although other types of media may be used. The antifog medium 645 can remove salt from the exhaust stream, which can be directed out of an exhaust 651 from the salt collector 610A. In some cases, a dilution inlet 653 may introduce additional air into the exhaust stream for further dilution of the particulate matter, for example, before the exhaust stream is further directed through a fan and / or a bag filter. In some cases, the temperature may be monitored and / or regulated to facilitate conditions that cause the droplets 647 to coalesce. A temperature at a reference point 655 downstream of the anti-fog medium 645 may be measured by a suitable temperature sensor and provide an indication for adjusting the amount of water and / or air introduced through the water and / or air inlet 643. For example, an increase in the introduced air and / or water may be triggered to decrease a downstream temperature, or a decrease in the introduced air and / or water may be triggered to increase a downstream temperature. As an illustrative example, the water and / or air introduced through the water and / or air inlet 643 may be modulated to a target downstream temperature of 800°C at reference point 655 and / or an inlet temperature of 850°C adjacent to the water and / or air inlet 643. Several elements can be included to process the regenerated salt 650 from the liquid salt bath contained in the tank 649. For example, the regenerated salt 650 from the salt bath can be conveyed by means of a salt melter 657. In some cases, the regenerated salt 650 can be fed into a cooler 659 and / or a crusher 661. In some cases, an optional supply path 648 can redirect the regenerated salt 650 (e.g., in a liquid or solid state) back to the reaction chamber 602 (e.g., via the feed chute 640). Figure 7 is a flow diagram describing process 700 for extracting salt from granules, in accordance with certain aspects of the present description. Process 700 can be carried out using system 600 of Figure 6. Process 700 can be carried out using granules 228 and 328 of Figures 2 and 3, respectively. In block 702, a reaction vessel may be charged with the granules (e.g., pellets). In some cases, charging the vessel with the granules may involve introducing the granules into the ML / a / ZUZ l / U 1 D / U1 reaction vessel. In some cases, loading the vessel with the granules may involve generating the granules within the reaction vessel through melting the waste metal. In some cases, the granules may include white granules, and additional steps may be taken to generate salt slag and extract the metal from the white granules. In optional block 704, salt may be added to the white granules. In optional block 706, the white granules may be brought into contact with the salt at an initial temperature. This contact and heating may facilitate the extraction of metal from the white granules and may facilitate the generation of salt slag. In block 708, the granules (e.g., black granules or salt slag) may be heated to a temperature high enough to evaporate the salt (e.g., 1200°C or higher). In some cases, the granules may be heated to a temperature close to, at, or above the boiling point of the salt within the granules. Heating the granules may involve supplying heat from a heat source (e.g., an oxyfuel burner) or supplying oxygen to facilitate the oxidation of the fuel within the reaction vessel (e.g., residual carbon). In block 710, the salt may be allowed to evaporate as salt vapor. In some cases, blocks 708 and / or 710 may occur for a duration sufficient to evaporate a desired amount of salt (e.g., 95%, 99%, or 99.9%) from the granules. In block 712, the salt vapor may be directed to a gas outlet. In block 714, salt vapor can be captured.In block 716, the salt vapor can condense into salt (e.g., solid or liquid salt). In some cases, the salt regenerated in block 716 can be reused in a subsequent block 704 to supply salt for later white slag production. In some cases, the salt regenerated in block 716 can be reused for a purpose other than generating later salt slag. For example, in some cases, the salt regenerated in block 716 can be used to facilitate the smelting of scrap metal. In some cases, the salt vapor can be measured in the optional block 718 to obtain a measurement of the salt concentration in the vapor. Based on the measurement in block 718, a determination can be made to stop heating the granules and evaporating the salt in blocks 708 and 710. In some cases, this determination can be associated with the evaporation of a desired quantity of salt, as determined by the measurement in block 718. In some cases, additional black granules can be added to the reaction vessel in the optional block 720. The additional black granules can allow larger quantities of salt to evaporate and regenerate in blocks 710, 712, 714, and 716. In some cases, the addition of black granules in block 720 can improve the heat treatment efficiency of the subsequent white granules. The results of a sample test are shown in the table below. In these test runs, samples of the pellets used had an initial salt level of approximately 50% and were subjected to the indicated temperatures and times to obtain the measured percentages of salt removed and residual chloride. These results indicated that by operating at elevated temperatures (e.g., at or above the boiling points of salt, or even below but near such points), residual chloride salts can be reduced by more than 99%, and that the resulting calcined oxide residue can be non-reactive and considered non-hazardous for transport, use, and disposal under the Toxicity Characteristic Leaching Procedure (TCLP) standards established by the Environmental Protection Agency (EPA). iviA / a / ¿u¿ ι / u io / ui Run # Initial Temperature (°C) Maximum Temperature (°C) Total Time (minutes) Salt Removed (%) Residual Chloride (%) 1 1350 1530 90 99.5 0.10 2 1350 1520 90 99.7 0.06 3 1300 1565 100 99.8 0.04 4 1300 1510 90 99.9 0.03 5 1300 1500 90 97.6 0.49 6 1300 1440 135 98.3 0.34 7 1450 1550 90 99.6 0.08 8 1350 1450 90 99.7 0.07 9 1350 1600 90 99.9 0.03 10 1350 1460 90 99.8 0.04 Figure 8 is a schematic diagram describing the two-stage process for heat-treating the granules, according to certain aspects of the present description. In a first stage, the white granules can be heated in a reaction vessel, in combination with salt, to a first temperature (e.g., 800°C or approximately 800°C) to extract the metal and generate salt slag. In a second stage, the salt slag and optional black granules can be heated in a reaction vessel (e.g., the same or a different reaction vessel) to a second temperature, which is high enough to extract the salt as salt vapor and result in inert oxides. In some cases, the second temperature is at or above the boiling point of the salt (e.g., 1500°C or approximately 1500°C). The extracted salt can be reused in the first stage for further treatment. Figure 9 is a schematic diagram describing a two-stage, single-vessel process 900 for the heat treatment of granules, according to certain aspects of the present description. Process 900 may be the same as Process 800, however, specifically carried out in a single vessel. In a first stage, the white granules may be heated within a reaction vessel, in combination with salt, to a first temperature (e.g., 800°C or approximately) to extract the metal and generate salt slag. In a second stage, the salt slag within the reaction vessel may be further heated to a second temperature, which is high enough to extract the salt as salt vapor and produce salt-free oxides (e.g., 1200°C or higher). In some cases, the second temperature is at or exceeds the boiling point of the salt (e.g., 1500°C or approximately).In some cases, black granules can be optionally added to the reaction vessel between the first and second stages. The salt extracted in the second stage can be reused in the first stage of a subsequent treatment. The preceding description of the modalities, including the illustrated ones, is presented for illustrative and descriptive purposes only and is not intended to be exhaustive or limiting to the precise forms described. Numerous modifications, adaptations, and uses of these modalities will be evident to those experienced in the technique. As used below, any reference to a series of examples should be understood as a reference to each of those examples disjunctively (e.g., “Examples 1-4” should be understood as “Examples 1, 2, 3 or 4”). Example 1 is a method for the pretreatment of granules, comprising: receiving the granule pieces; disintegrating the granule pieces into granule particles of, or below, 10 mm in diameter; agglomerating the granule particles into pellets, wherein the pellets comprise channels when heated to temperatures of, or above, 800°C. In some cases, the pellets comprise channels when heated to temperatures of, or above, 500°C. Example 2 is the method of Examples 1, further comprising: mixing the granule particles with an additive, wherein the additive is selected to oxidize or otherwise decompose at temperatures of, or below, 800°C, and wherein the oxidation or decomposition of the additive facilitates the exposure of the granule channels. Example 3 is the method of Examples 2, where the additive comprises post-consumer waste or scrap materials from other industries. Example 4 is the method of Examples 1-3, which further comprises extracting metallic aluminum from the granule particles, using an eddy current separator before agglomeration of the granule particles. Example 5 is the method of Examples 1-4, further comprising sieving the granule particles before agglomerating the granule particles, wherein the sieving comprises removing oversized granule particles. Example 6 is the method of Examples 5, wherein the removal of oversized granule particles comprises directing the oversized granule particles to be further disintegrated. Example 7 is the method of Examples 5, wherein the removal of oversized granule particles comprises directing the oversized granule particles to thermal processing. Example 8 is the method of Examples 1-7, further comprising: mixing the pellet particles with a fuel additive, wherein the fuel additive is selected to facilitate the supply of fuel from a pellet treatment reaction. Example 9 is the method of Examples 1-8, where each of the granules has an average diameter within the range of 5 mm to 50 mm. Example 10 is the method of Examples 1-9, wherein the granule pieces comprise aluminum oxides and salt. Example 11 is a method for treating a by-product of metal recycling, comprising: providing granules of the slag, wherein each granule of the slag comprises the slag and an additive selected to oxidize or decompose at a channel exposure temperature of, or below, 800°C, and wherein the additive is placed within the granule to reveal channels in the granule upon oxidation; heating the granules of the slag to a temperature of, or above, the channel exposure temperature, oxidizing or decomposing the additive to expose channels in each granule, wherein the channels in a granule allow gas to enter and pass through the granule; and maintaining the granules of the slag at the temperature to perform the thermal processing of the granules. In some cases, the heating of the granules of the granules can be at a temperature of, or below, 500°C or of, or below, 800°C. Example 12 is the method of Example 11, where the execution of the thermal processing involves evaporating the salt from the granules of the granules. Example 13 is the method of Examples 11 or 12, where the additive comprises post-consumer waste or scrap materials from other industries. Example 14 is the method of Examples 11-13, wherein the granules of the pellets further comprise a fuel additive selected to facilitate the fuel supply of the thermal processing. Example 15 is the method of Examples 11-14, wherein each of the granules in the granules has an average diameter within the range of 5 mm to 50 mm. Example 16 is the method of Examples 11-15, further comprising removing the treated granules from the pellets after thermal processing of the pellets, wherein the treated pellets have a carbon content of 1% or less by weight. Example 17 is a reconstituted metal recycling by-product comprising granules, wherein the granules comprise aluminum oxides; and an additive selected to oxidize or decompose at a temperature of, or below, 800°C; wherein the granules and the additive are agglomerated together into a pellet, and wherein the additive is located within the pellet, such that one or more channels through the pellet are exposed upon oxidation of the additive. Example 18 is the reconstituted by-product of metal recycling from Example 17, wherein the additive comprises post-consumer waste or scrap materials from other industries. Example 19 is the reconstituted by-product of metal recycling from Examples 17 or 18, wherein the granule pellets comprise agglomerated granule particles, each having an average diameter of, or below, 10 mm. ινΐΛ / a / zuz ι / u io / ui Example 20 is the reconstituted by-product of metal recycling from Examples 17-19, further comprising a fuel additive, wherein the fuel additive is selected to facilitate fuel supply from a pellet treatment reaction. Example 21 is the reconstituted by-product of metal recycling from Examples 17-20, wherein each of the granules has an average diameter within the range of 5 mm to 50 mm. Example 22 is the reconstituted by-product of metal recycling from Examples 17-21, wherein the granules also comprise salt. Example 23 is a method for extracting salt from a by-product of metal recycling, comprising: loading a container with granules comprising aluminum oxides and salt; heating the granules to a temperature high enough to evaporate the salt; maintaining the granules at the temperature to permit evaporation of the salt as salt vapor; directing the salt vapor out of the container through a gas outlet; and capturing the salt vapor. Example 24 is the method of Example 23, wherein the capture of salt vapor comprises condensing the salt vapor into solid or liquid salt. Example 25 is the method of Examples 23 or 24, wherein the salt comprises NaCl and the temperature is at or above approximately 1450°C. Example 26 is the method of Examples 23-25, wherein the salt comprises KOI and the temperature is at or above approximately 1416°C. Example 27 is the method of Examples 23-26, wherein the granules comprise compounds selected from the group consisting of nitrides, carbides, sulfides, and phosphides; and wherein maintaining the granules at temperature further comprises maintaining the granules at temperature in an oxidizing medium. Example 28 is the method of Examples 23-27, wherein the granules comprise residual carbon, and wherein heating the granules to the temperature comprises oxidizing the residual carbon. Example 29 is the method of Examples 23-28, wherein the granules comprise residual metallic aluminum, and wherein heating the granules to the temperature comprises oxidizing the residual metallic aluminum. Example 30 is the method of Examples 23-29, wherein holding the granules at temperature comprises holding the granules at temperature until at least 95% of the salt has evaporated. Example 31 is the method of Examples 23-30, further comprising: removing the treated granules from the container, wherein the container contains residual heat after the removal of the treated granules; and loading the container with additional granules and treating the additional granules, wherein the treatment of the additional granules comprises utilizing the residual heat in the container. Example 32 is the method of Examples 23-31, wherein maintaining the granules at the temperature to allow evaporation of the salt further comprises detecting a concentration of the salt vapor coming out of the gas outlet and determining whether to stop maintaining the granules at the temperature, based on the detected concentration of the salt vapor. iviA / a / ¿u¿ ι / u io / ui Example 33 is the method of Example 32, wherein the detection of the salt vapor concentration comprises detecting an opacity of the salt vapor coming out of the gas outlet. Example 34 is a system for extracting salt from metal recycling by-products, comprising: a container for receiving pellets comprising aluminum oxides and salt; a heat source coupled to the container for heating the pellets to a temperature high enough to evaporate the salt as salt vapor; a gas outlet coupled to the container for transporting the gas and salt vapor from the container; and a salt collector coupled to the gas outlet for collecting and condensing the salt vapor. Example 35 is the system of Examples 34, wherein the salt comprises NaCl, and wherein the heat source is suitable for heating the granules to temperatures of, or above, approximately 1450°C. Example 36 is the system of Examples 34 or 35, wherein the salt comprises KCl and wherein the heat source is suitable for heating the granules to temperatures of, or above, approximately 1416°C. In some cases, the salt comprises both KCl and NaCl. Example 37 is the system of Examples 34-36, wherein the container contains an oxygen inlet to establish an oxidizing medium; and wherein the granules comprise compounds selected from the group consisting of nitrides, carbides, sulfides, and phosphides. Example 38 is the system of Examples 34-37, wherein the container contains an oxygen inlet to establish an oxidizing medium; wherein the granules comprise residual carbon; and wherein the oxidizing medium is suitable for oxidizing the residual carbon to facilitate heating the granules to the temperature. Example 39 is the system of Examples 34-38, wherein the container contains an oxygen inlet to establish an oxidizing medium; wherein the granules comprise residual metallic aluminum; and wherein the oxidizing medium is suitable for oxidizing the residual metallic aluminum to facilitate heating the granules to the temperature. Example 40 is the system of Examples 33-39, which further comprises a sensor for detecting a concentration of the salt vapor coming out of the gas outlet. Example 41 is the system of Example 40, wherein the sensor comprises an optical sensor to detect an opacity of the salt vapor coming out of the gas outlet. Example 42 is the system of Examples 34-41, wherein the heat source comprises an oxyfuel burner. Example 43 is a method for processing a byproduct of metal recycling, comprising: loading a container with white granules comprising aluminum oxides; introducing salt into the container; contacting the white granules with the salt at a first temperature to facilitate the extraction of the metal from the white granules and the generation of salt slag; heating the salt slag to a second temperature sufficiently high to evaporate the salt, wherein the first temperature is lower than the second temperature; maintaining the salt slag at the second temperature to allow the evaporation of the salt as salt vapor, wherein the evaporation of the salt from the salt slag results in inert oxides; discharging the inert oxides; collecting the salt vapor and condensing the salt vapor into the salt; and reusing the salt to generate further salt slag by contacting the salt IVIA / a / ZUZ l / UID / UI reused with the later white chaff. Example 44 is the method of Example 43, in which the contact of the white granules with the salt at the first temperature and the heating of the salt slag to the second temperature occurs in the container. Example 45 is the method of Example 44, wherein the vessel contains residual heat after the discharge of the inert oxides and wherein the generation of the subsequent salt slag comprises utilizing the residual heat in the vessel. Example 46 is the method of Examples 43-45, wherein the salt comprises NaCl and the second temperature is at or above approximately 1450°C. Example 47 is the method of Examples 43-46, wherein the salt comprises KCI and the second temperature is at or above approximately 1416°C. Example 48 is the method of Examples 43-47, wherein the white granules comprise compounds selected from the group consisting of nitrides, carbides, sulfides, and phosphides; and wherein the maintenance of the salt slag at the second temperature further comprises maintaining the salt slag at the second temperature in an oxidizing medium. Example 49 is the method of Examples 43-48, wherein the salt slag comprises residual metallic aluminum, and wherein heating the salt slag to the second temperature comprises oxidizing the residual metallic aluminum. Example 50 is the method of Examples 43-49, wherein maintaining the salt slag at the second temperature comprises maintaining the salt slag at the second temperature until at least 95% of the salt has evaporated. Example 51 is the method of Examples 43-50, wherein maintaining the salt slag at the second temperature to allow evaporation of the salt further comprises detecting a concentration of the salt vapor coming out of the vessel, and determining whether to stop maintaining the salt slag at the second temperature, based on the detected concentration of the salt vapor. Example 52 is the method of Example 51, wherein the detection of the salt vapor concentration comprises detecting an opacity of the salt vapor. Example 53 is the method of Examples 43-51, which further comprises reusing at least a portion of the reused salt for a use other than generating the subsequent salt slag. Example 54 is the method of Example 53, wherein the use other than generating the subsequent salt slag involves using the salt to facilitate the melting of the waste metal.

Claims

1. A system for extracting salt from metal recycling by-products, comprising: a container for receiving granules comprising aluminum oxides and salt; a heat source coupled to the container for heating the granules to a sufficiently high temperature to evaporate the salt as salt vapor; a gas outlet coupled to the container for transporting the gas and salt vapor from the container; and a salt collector coupled to the gas outlet for collecting and condensing the salt vapor.

2. The system according to claim 1, wherein the salt comprises NaCl and wherein the heat source is suitable for heating the granules to temperatures of, or above, 1450°C.

3. The system according to claim 1 or 2, wherein the salt comprises KCl and wherein the heat source is suitable for heating the granules to temperatures of, or above, 1416°C.

4. The system according to any of claims 1 to 3, wherein the container contains an oxygen inlet for establishing an oxidizing medium; and wherein the granules comprise compounds selected from the group consisting of nitrides, carbides, sulfides, and phosphides.

5. The system according to any of claims 1 to 4, wherein the container contains an oxygen inlet for establishing an oxidizing medium; wherein the granules comprise residual carbon; and wherein the oxidizing medium is suitable for oxidizing the residual carbon to facilitate heating the granules to the temperature.

6. The system according to any one of claims 1 to 5, wherein the container contains an oxygen inlet for establishing an oxidizing medium; wherein the granules comprise residual metallic aluminum; and wherein the oxidizing medium is suitable for oxidizing the residual metallic aluminum to facilitate heating the granules to the temperature. The system according to any one of claims 1 to 6, further comprising a sensor for detecting a concentration of the salt vapor exiting the gas outlet.

8. The system according to claim 7, wherein the sensor comprises an optical sensor for detecting an opacity of the salt vapor coming out of the gas outlet.

9. The system in accordance with any of claims 1 to 8, wherein the heat source comprises an oxyfuel burner.

10. A method for extracting salt from metal recycling by-products using the system according to claim 1, comprising: loading the container with granules comprising aluminum oxides and salt; heating the granules to a temperature to evaporate the salt; maintaining the granules at the temperature to permit evaporation of the salt as salt vapor; directing the salt vapor out of the container through the gas outlet; and capturing the salt vapor.

11. The method according to claim 10, wherein the capture of the salt vapor comprises condensing the salt vapor into solid or liquid salt.

12. The method according to claims 10 or 11, wherein the salt comprises NaCl and the temperature is at or above 1450°C.

13. The method according to any of claims 10 to 12, wherein the salt comprises KCl and the temperature is at or above 1416°C.

14. The method according to any of claims 10 to 13, wherein the granules comprise compounds selected from the group consisting of nitrides, carbides, sulfides, and phosphides; and wherein maintaining the granules at the temperature further comprises maintaining the granules at the temperature in an oxidizing medium.

15. The method according to any of claims 10 to 14, wherein the granules comprise residual carbon, and wherein heating the granules to the temperature comprises oxidizing the residual carbon.

16. The method according to any of claims 10 to 15, wherein the granules comprise residual metallic aluminum, and wherein heating the granules to the temperature comprises oxidizing the residual metallic aluminum.

17. The method according to any of claims 10 to 16, wherein maintaining the granules at the temperature comprises maintaining the granules at the temperature until at least 95% of the salt has evaporated.

18. The method according to any of claims 10 to 17, further comprising: removing the treated granules from the container, wherein the container contains residual heat after the removal of the treated granules; and loading the container with additional granules and treating the additional granules, wherein the treatment of the additional granules comprises utilizing the residual heat in the container.

19. The method according to any of claims 10 to 18, wherein maintaining the granules at the temperature to allow evaporation of the salt further comprises detecting a concentration of the salt vapor coming out of the gas outlet, and determining whether to stop maintaining the granules at the temperature, based on the detected concentration of the salt vapor.

20. The method according to claim 19, wherein the detection of the salt vapor concentration comprises detecting an opacity of the salt vapor coming out of the gas outlet.