Zinc oxide recovery from reclaimed carbon by carbothermal reduction

Abstract

A process for deashing reclaimed carbon that contains zinc sulfide involves the reaction of the zinc sulfide with a gas containing products of combustion such as, for example, carbon dioxide, to produce zinc vapors and a treated reclaimed carbon. Combustion of the zinc vapors with oxygen generates zinc oxide and flue gas containing products of combustion. At least a portion of the flue gas is recycled to provide heat and reactants to the zinc vaporization reaction.

Description

Docket: 2024701TITLEZinc Recovery from Reclaimed Carbon by Carbothermal ReductionBACKGROUND

[0001] Since a significant quantity of carbon black (CB) is used to reinforce the rubber components of tires, used tires and other CB reinforced rubber products represent a significant waste stream. To dispose of this stream, used tires can be pyrolyzed in an oxygen depleted atmosphere, for example. Tire pyrolysis products can include organic vapors, steel, fiber, oil, and a carbon-containing solid residue.

[0002] Further processing can be undertaken. For instance, the organic vapors can be condensed to a liquid oil phase, while the steel can be reclaimed as steel wire. Efforts also have been made to recycle carbon reclaimed from end-of-life tires (or other sources). The possibility of using this reclaimed carbon as a substitute for CB in rubber applications has been considered as a promising strategy.

[0003] Tires and other rubbers contain a variety of CBs, having various morphologies, along with other additives or fillers. The composition and / or microstructure of the original CBs, however, is not preserved in the resulting reclaimed carbon (rC). Consequently, reclaimed carbon suffers from low rubber reinforcement, such as low tensile modulus, low tear strength, and / or low fatigue life, compared to a CB with the same or about the same surface area and structure as measured by OAN.

[0004] Attempts to improve the performance of rC in elastomers is described, for example, in International Application Publication WO2023 / 122582, incorporated herein by this reference. International Application Publication 2025 / 006552, also incorporated herein by this reference, presents methods for processing rC using media milling.SUMMARY

[0005] The above and other features of the disclosure, including various details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It willDocket: 2024701be understood that the particular method and device embodying the disclosure are shown by way of illustration and not as a limitation of the disclosure. The principles and features of this disclosure may be employed in various and numerous embodiments without departing from the scope of the disclosure.

[0006] Despite ongoing recycling efforts, a need continues to exist for exploiting materials generated in the pyrolysis of end-of-life tires or other rubber products. For example, a need exists for improving the performance of rC in rubber and / or other applications. A need also exists for recovering non-carbon constituents found in reclaimed carbon.

[0007] Described below are approaches that address at least some of these needs.

[0008] As used herein, “carbon black” means elemental carbon-containing particles of carbon coalesced into aggregates and agglomerates and obtained by partial combustion or thermal decomposition of hydrocarbons.

[0009] As used herein, “pyrolysis carbon” includes char, raw reclaimed carbon, processed reclaimed carbon, and dry milled reclaimed carbon.

[0010] As used herein, “reclaimed carbon” is raw reclaimed carbon that has been processed to remove macroscopic contaminants and that has optionally been further milled. Thus, processed reclaimed carbon, milled reclaimed carbon, dry milled reclaimed carbon, and wet milled reclaimed carbon all fall under the definition of reclaimed carbon.

[0011] As used herein, “raw reclaimed carbon” is solid material resulting from pyrolysis of rubber goods that contain carbonaceous particulate fillers, including but not limited to carbon black, in any amount.

[0012] As used herein, “processed reclaimed carbon” means raw reclaimed carbon that has been processed to remove at least one macroscopic contaminant such as fabric or wire.

[0013] As used herein, “milled reclaimed carbon” or “milled rC” is pyrolysis carbon that is substantially free of macroscopic contaminants and that has been milled.

[0014]

[0015] As used herein, “char” is the solid, carbonaceous residue left behind after the rubber in a tire is broken down during the pyrolysis process.Docket: 2024701

[0016] As used herein, “ash” refers to the inorganic residue generated in the pyrolysis of spent rubber and is typically composed of minerals such as zinc sulfide, zinc oxide, crystalline silica, and amorphous silica. Smaller amounts of aluminum (Al), iron (Fe), alkaline earth metals, and / or alkali metals can be present as well.

[0017] As used herein, “treated rC” refers to a rC that has a lower ash content compared to the ash content of the initial rC fed to a process, a deashing process, for instance. In embodiments, the treated rC has a zinc content that is lower than the zinc content in the initial (also referred to herein as the “feed”, “starting” or “input”) rC introduced to the process. For example, the zinc content in the treated rC can be less than or equal to 2 wt%.

[0018] In many cases, ash has a negative effect on the performance of rC in rubber applications and aspects of the disclosure pertain to approaches for removing at least some ash components. Although the precise mechanism remains unclear, it is believed that ash serves as a binder. Without being bound by any theory, the removal of this “binder” can improve the rC dispersion in rubber by weakening agglomerate strength and enhancing rubber-particle interactions.

[0019] One embodiment described herein features a process for deashing rC . In the process, rC containing a zinc compound, e.g., zinc sulfide (ZnS), and a carrier gas, a flue gas, for instance, are heated at a temperature sufficiently high to reduce ZnS and produce zinc vapors and a treated rC. This ZnS vaporization operation can be conducted in a kiln, a kiln section (or zone) of a larger system, or in another suitable apparatus. In some implementations, the initial rC being deashed is milled rC.

[0020] The treated rC can be removed from the process as one of the products, while the zinc vapors react with oxygen, e.g., in a burner, a combustion section (or zone) of a larger system, or in another suitable apparatus. This combustion operation generates solid zinc oxide (ZnO), which can be collected as another process product, and exhaust (flue) gas.

[0021] Combustion-generated, the flue gas is rich in combustion products such as carbon dioxide (CO2). It also has a temperature that is higher and typically considerably higher than the ambient (atmospheric temperature).Docket: 2024701

[0022] In many implementations, at least a portion of the flue gas is recirculated to the first stage of the process, the stage that involves the formation of Zn vapors and treated rC, where it supplies a reactant such as CO2. It can also supply a fraction of the energy (heat) needed for the endothermic reduction of a compound such as ZnS. In addition to reducing energy (heating) requirements, recycling flue gas lowers the abatement measures needed to treat the exhaust gas before its release into the environment.

[0023] The process described herein exploits a waste stream derived from spent rubber articles to produce useful materials. The ZnO product, for instance, can find applications in various industries including but not limited to rubber, ceramics, pharmaceuticals, paints, cosmetics, lubricants, and so forth. Having a lower ash content, the treated rC is believed to display improved performance in rubber or other applications. The treated rC can be used “as is”, in combination with virgin CB, for instance, or can be further processed.

[0024] In some arrangements, the process described herein reduces or minimizes carbon loss due to carbon gasification. Thus, the treated rC can contain 80 wt% or more of the carbon present in the starting rC.

[0025] Advantageously, techniques described herein can be conducted using or adapting existing equipment, a Waelz rotary kiln, for example.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the disclosure. Of the drawings:

[0027] The Figure is a diagram showing an embodiment of the process described herein.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so thatDocket: 2024701this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0029] Given its circular nature, significant efforts have been made to incorporate rC into tire production as a sustainable replacement for CB. Typical commercial rC contains a significant fraction of micron-scale, compacted particles that lead to low rigidity and reinforcement when compounded in rubber, behaving more like a thermal black than a reinforcing or semi-reinforcing CB.

[0030] A solid byproduct of waste tire pyrolysis, rC typically contains CB, char and ash. The ash often includes amorphous silica and a zinc component (constituent). Smaller amounts of iron (Fe), aluminum (Al), and / or alkali metals can be present as well. In many of the embodiments described, the Zn component comprises, consists essentially of, or consists of ZnS.

[0031] In many of its aspects, the present disclosure relates to a dry, gas phase deashing process for removing at least a portion of the zinc component, e.g., ZnS, initially present in rC. The process includes heating rC that includes a Zn compound, e g., ZnS, in a reducing atmosphere, to produce: (a) Zn vapors and (b) a treated rC. In a subsequent stage, the Zn vapors react with oxygen to form ZnO and products of combustion in the form of a flue gas. In embodiments, at least a portion of the flue gas is recirculated (recycled) to provide reactant(s), such as CO2, and much of the heat needed to form zinc in gaseous (Zn vapors) form from the zinc compound (e.g., ZnS) present in the initial rC.

[0032] In one example, ZnS present in reclaimed carbon is reduced in a kiln or a kiln-like section (or zone) of a larger arrangement (system), while the combustion of the Zn vapors with oxygen can be carried out in a burner or a burner-like combustion section (or zone) of the larger arrangement (system).

[0033] In more detail, the deashing process described herein can be conducted using independent units such a kiln, burner, other equipment units, conduits (supporting flow of materials from one unit to another), flow, pressure, temperature, etc. controls, automation features, computer support, and / or other equipment components.Docket: 2024701

[0034] It is also possible to conduct the deashing process in a larger system, e.g., an arrangement that integrates some of the operations described herein, using zones or stages of a larger arrangement. In addition to a kiln and / or a combustion zone, larger arrangements can include flow pathways for moving materials through the system, controls (temperature, pressure, flow), automation features, computer support and / or other components.

[0035] In embodiments, the deashing process (or steps thereof) can be conducted in a Waelz rotary kiln or in another suitable equipment for conducting a conventional Waelz process.

[0036] A method for selectively extracting Zn oxide (ZnO) from a solid mixture, the Waelz process leverages the low boiling point of Zn (and other metals such as Cd and Pb) to selectively extract them from a solid mixture. A description and analysis of the conventional Waelz process is provided, for example, by Araujo Neto et al., Process Safety and Environmental Protection (2021) 149, 442-450 and Suetens et al., Journal of Cleaner Production (2014) 65, 152-167), both articles being incorporated herein by this reference.

[0037] Briefly, in the conventional Waelz process, Zn-containing solid feed, such as electric arc furnace dust (EAFD), is pelletized with a solid carbon source such as petroleum coke and fed into a direct-fired rotary kiln heated to 1000-1500 °C by a hot burner exhaust gas in counter-current flow. Carbothermal reduction of metal oxides occurs under the reducing environment:C (s) + CO2 (g) - 2 CO (g)C (s) + H2O (g) — CO (g) + H2 (g)ZnO (s) + CO (g) - Zn (g) + CO2 (g)Fe2O3(s) + 3 CO (g) 2 Fe (s) + 3 CO2 (g)

[0038] Zn volatilizes and is oxidized to ZnO in the gas phase, which is entrained as a fine powder in the offgas and can be separated, e.g., by dust separation techniques. The residual slag containing nonvolatile metals (e.g., Fe) and poorly reducible oxides (e.g., AI2O3, SiO2, CaO) is quenched and can be landfilled or used for other purposes.Docket: 2024701

[0039] The process disclosed herein, however, cannot be conducted according to the traditional Waelz approach for processing EAFD. Compared to that of ZnO, for instance, the reduction of ZnS requires higher reaction temperatures to achieve the same yield of Zn.Furthermore, using rC as feedstock poses the additional challenge of maximizing selectivity for ZnS reduction over carbon gasification. For instance, if the kiln is powered by a natural gas fired burner exhaust, as in the traditional Waelz process, the high concentrations of oxygen-containing compounds (CO2, H2O, O2) lead to significant undesired carbon gasification, undermining the yield of the deashed carbon product.

[0040] One possible strategy for solving this problem relies on using a carrier gas, e.g., an inert gas stream, that is less oxidizing than the natural gas fired burner exhaust described above. While the energy needed to achieve the desired temperature and drive the endothermic reaction could be supplied by electrically preheating the less oxidizing carrier gas, such an approach is considered cost-prohibitive due to the large gas volumes and the high preheat temperatures required.

[0041] Addressing these difficulties, one embodiment of the present disclosure involves recycling (recirculating) at least a portion of flue gas generated in the process back to the ZnS reduction step. This recycling (recirculation) scheme provides and controls the concentrations of reactant(s), e.g., CO2. It also supplies at least a portion of the heat needed to reduce a zinc compound such as the ZnS present in the initial rC.

[0042] The process can be described in more detail with reference to arrangement 100, shown in the Figure. Although presented individually, one or more of the components in the arrangement 100 can be zones or stages in a system used to conduct a conventional Waelz process, zones or stages in a Waelz rotary kiln, for example.

[0043] In embodiments, the process is run continuously. The direction of the various flows or streams is represented by arrows. As used herein, terms such as “stream” or “flow” denote the progression (passage, movement, advance) of materials through a series (two or more) of steps or operations. Flow rates employed can vary, depending on equipment capacity, quantities of materials handled, equipment ratings, and / or other factors. Parameters such as flow rates amounts of materials handled, etc. can be determined by routineDocket: 2024701experimentation, modeling, or prior experience and can be monitored and / or adjusted manually or automatically using techniques and equipment known in the art.

[0044] Included in arrangement 100 are kiln 112 (for conducting an operation in which ZnS present in an initial rC is reduced to form Zn vapors), and burner 114 (for conducting an operation in which the Zn vapors are oxidized to form ZnO). rC is continuously fed to kiln 112 together with a hot carrier gas via feed stream 01. In typical cases, the input rC is in the form of a dry particulate material (e.g., granulated or pelletized rC) at ambient temperature.

[0045] In some implementations, the initial rC is pre-milled to provide an increased reactive surface area. The initial pre-milled rC can be prepared by wet milling, followed by a drying operation, or by other milling methods. Pre-milled rC and / or techniques that can be employed to obtain a pre-milled rC are described, for example, in International Publication Nos. WO2023 / 122582, WO2013 / 095145, WO 2025 / 006552, in US Patent No. 9,580,606 or U.S. Patent Application Publication No. 2020 / 123390.

[0046] Whether pre-milled or not, the feed rC in flow 01 comprises carbon (C) along with Zn compounds such as ZnS. In specific embodiments, the rC in feed stream 01 contains ZnS in an amount within a range from about 5 to about 12 by weight (wt%), e.g., from about 5 to about 8, or to about 10; or from about 8 to about 10, or to about 12 wt%; or from about 10 to about 12 wt%. In one example, the ZnS content in the starting rC is from about 7 to about 10 wt %. In another example, the zinc content in the rC in stream 01 is from about 5 to about 6 wt %;

[0047] The feed rC in stream 01 can have an ash content within a range from about 10 wt% to about 30 wt%, e.g., from about 10 to about 15, to about 20, or to about 25 wt%; or from about 15 to about 20, to about 25, or to about 30 wt%; or from about 20 to about 25, or to about 30 wt%; or from about 25 to about 30 wt%.

[0048] In typical applications, the feed rC, whether pre-milled or not, is dry, having a water content no greater than about 2 wt%, for example, no greater than about 1 wt% or about 0.5 wt%.

[0049] At a temperature of about 1100- 1500 degrees centigrade (°C), such as from about 1100 to about 1200, to about 1300, or to about 1400 °C; or from about 1200 to about 1300, toDocket: 2024701about 1400 or to about 1500 °C; or from about 1300 to about 1400 or to about 1500 °C; or from about 1400 to about 1500 °C, in the presence of the carbon found in the rC and a carrier gas rich in products of combustion (e.g., CO2), ZnS undergoes a carbothermal reduction to form Zn vapors. Assuming that all species equilibrate, there are several equivalent ways to write the set of reactions taking place in the kiln. In one example (the double-headed arrows indicating the establishment of equilibrium):CO2 + C 2 COC + O2 CO2ZnS + CO Zn + COS2 COS + C CS2 + 2 CO

[0050] From kiln 112, kiln output 02, containing species such treated rC and gaseous constituents such as Zn vapors, CO, N2, CS2, etc., is directed to kiln separator 116, where solid treated rC, also referred to herein as “deashed” rC, is separated from kiln offgas 04, which carries the vaporized Zn to burner 114.

[0051] Kiln separator 116 can be any unit able to separate and recover the treated rC solids from the hot offgas, such as a gravity-fed hopper or a hot gas filter.

[0052] Depending on the composition of the input rC, the deashing process described herein can extend to compounds other than ZnS. For instance, in addition to ZnS, the initial rC (stream 01) may contain other metal compounds, such as, for example, zinc oxide. In many cases, the relatively high heat needed to vaporize ZnS is sufficient to vaporize at least some of these other metal compounds. To illustrate, the process described herein can reduce ZnO, producing Zn vapors, as in a traditional Waelz process, resulting in a treated rC that can be entirely free of ZnO.

[0053] However, kiln conditions aimed to vaporize ZnS may not eliminate other components in the input rC. Accordingly, if present, species such as alumina, silica, other transition metal oxides, aluminosilicates, etc. are directed to separator 116 via kiln output 02, and are extracted along with treated rC via flow 03.Docket: 2024701

[0054] In many implementations, at least 50 wt % of the initial zinc present in the input rC (stream 01) is removed. For instance, at least 60, 70, 80, 90, 95 or even 100 wt % of the initial zinc present in the feed rC can be removed. In one example, the Zn amount in the treated rC is no greater than about 10, than about 8, than about 5, than about 2, than about 1, or than about 0 wt %. In another example, the Zn content in the treated rC is within a range from about 0 to about 2 wt%.

[0055] With the removal of ZnS (and, if present, the removal of other metal compounds such as ZnO), the treated rC contains less ash than the rC initially introduced to the process via stream 01. For instance, ash can be reduced by about 10% or more relative to the starting ash content.

[0056] The process can further include collecting the treated rC. A quenching operation, e.g., in water, using, for example, quench sprays, or another suitable technique, can be used to cool the treated rC, e.g., to the ambient temperature (about 25°C, for instance).

[0057] If desired, the treated rC may be further processed to reduce the concentrations of other ash components, for instance by NaOH treatment as detailed in Chaala et al., Fuel Processing Technology (1996) 46, 1-15, incorporated herein by reference. The treated rC can also be milled and / or granulated. Milling can be conducted by methods described, for instance, in International Patent Application Publication No. WO 2025 / 006552, US2025 / 0092265, incorporated herein by reference in their entirety, or other suitable techniques. Granulation can involve pelletizing wet treated rC to form pellets or spray drying. A further operation may be undertaken to dry the pellets.

[0058] The gas phase components generated in the kiln, including Zn vapors, along with nitrogen gas (N2), CO, sulfur-containing gases, etc., are directed as kiln offgas 04 to burner 114 for further processing, specifically the formation of ZnO through the combustion of Zn vapors with oxygen (introduced via air flow 05). While air is a convenient source of oxygen, oxygen-enriched air, other suitable oxygen containing mixtures, or oxygen gas also can be employed.

[0059] In embodiments, the primary combustion (PC), defined as the amount of oxygen supplied to the burner divided by the theoretical amount of oxygen required to completelyDocket: 2024701combust the feed, is conducted with excess oxygen (PC > 100%). In one example, the burner PC is run at 200% to 330%, e.g., at 270%.

[0060] With respect to conditions, stream 05 can be at ambient temperature while kiln offgas 04, coming off kiln 112 and separator 116, is considerably hotter, yet not as hot as the kiln output 02 (which can be at about 1300°). To prevent zinc from condensing, kiln offgas 04 should also have a temperature greater than that of the boiling point of zinc. In one example, kiln offgas 04 has a temperature within a range from about 950 to about 1250 °C.

[0061] Reactions taking place in the burner can include:CO + 0.5 O2-> CO2Zn + 0.5 O2 -> ZnOCS2 + 3 O2 -> CO2 + 2 SO2COS + 1.5 O2 -> CO2 + SO2

[0062] Burner output 06, containing solid ZnO, is directed to a filtration apparatus 118 (e.g., a cyclone separator, bag filter, or electrostatic precipitator), where ZnO (product output 08) is separated from a burner flue gas (stream 07 in the Figure).

[0063] The process can further include collecting or recovering the ZnO product (stream 08), for further use in rubber, ceramics, pharmaceuticals, paints, cosmetics, lubricants, or other applications.

[0064] A quenching operation, e.g., in water, utilizing quenching tanks, spray tower systems, or another suitable technique, can be employed to lower the temperature of the ZnO, e.g., to the ambient temperature (about 25°C, for instance). Further processing, e.g., dissolution followed by electrowinning or precipitation, can provide a zinc product suitable for a desired end-use.

[0065] In many cases, the ZnO product recovered from the process can be comparable to, or purer than, the ZnO obtained in a traditional Waelz process. For instance, the Zn product can have a zinc content of at least about 60 wt%, e.g., within a range from about 60 to about 70 or to about 80 wt %; or from about 70 to about 80 wt%.Docket: 2024701

[0066] Flue gas (stream 07) generated in the burner can be split (device 120, a T-junction, for example) into stream 09, purged from the system, and stream 10, which is recycled back to kiln 112. The relative amounts of the purge gas (stream 09) and the recycled flue gas (stream 10) can vary. Since the flue gas recycle ratio (defined as the molar flow rate of stream 10 divided by the molar flow rate of stream 07) can affect composition, it can be selected to yield combustion products with a desired composition or within a desired composition range. In embodiments, the flue gas recycle ratio is within a range from about 0.05 to about 0.5. In one example, flow 10 is about 20 to about 25 kmol / hour, while flow 09 can be about 75 to about 80 kmol / hour.

[0067] As discussed, stream 10 is rich in products of combustion, useful for the reduction of ZnS in the kiln. This stream also provides some of the heat required to carry out the reduction. In the case of a ZnS reduction conducted at about 1300 °C, a formula that can be used to determine the fraction of energy provided by the recycled flue gas relative to the energy required to reduce ZnS is: (enthalpy of stream 10) / (enthalpy of stream 02 - enthalpy of stream 01 - enthalpy change of heating stream 01 from 25 °C to 1300 °C).

[0068] For an air-fired burner, the flue-gas recycling arrangement described herein can provide about 30 % of the energy required to carry out the ZnS reduction. Higher amounts may be possible, e.g., using an oxygen-fired burner. In illustrative examples, the energy supplied via flue gas recycling could represent 5 to 10, 5 to 15, 5 to 20, 5 to 25 or 5 to 30%; or 10 to 15, 10 to 20, 10 to 25 or 10 to 30%; or 15 to 20, 15 to 25 or 15 to 30%; or 20 to 25 or 20 to 30%; or 25 to 30% of the energy needed to conduct the reduction of ZnS.

[0069] Any additional energy needed can be supplied via methods known to those skilled in the art, such as indirect firing (e.g., using a hot burner exhaust gas in the shell side) or electrical heating (e.g., resistive heating, inductive heating, microwave heating, or a plasma source).

[0070] In theory, the minimum carbon loss in a process such as described herein can be calculated according to the following reaction, which indicates that one mole (97.4 g) of ZnS reacts with 0.5 mole (6.0 g) of carbon:ZnS + ' / 2C -> Zn + ' / 2CS2Docket: 2024701According to this equation, the carbon loss for a starting rC containing 10 wt% ZnS would be 0.6 wt%.

[0071] In practice, however, carbon gasification can represent a significant carbon loss pathway, further reducing the amount of carbon recovered in the treated rC.

[0072] It was discovered that the amount of carbon lost to gasification is affected by the composition of the flue gas (and thus the composition of the hot carrier gas fed to the kiln). Too much oxygen, for example, can increase carbon loss at the detriment of treated rC yields. Accordingly, some embodiments of the disclosure are directed to controlling (managing) the flue gas composition (and thus that of stream 10), with respect to carbon dioxide (CO2), N2, O2, etc., for example. In specific implementations, the flue gas contains O2 in an amount no greater than about 12 mol %, e.g., within a range from about 2 to about 12 mol %. The composition of the flue gas (stream 07) or recycled flue gas (stream 10) can be determined using suitable sensors and / or analytical devices known in the art.

[0073] Determining the desired process parameters for reduced carbon losses may be based on routine experimentation, process modeling (simulations), prior experience and / or other factors. Measures that can be taken to reach the desired parameters rely on controlling combustion parameters (burner PC, burner design, combustion temperatures, etc.), the composition of the offgas generated in the kiln, which, in turn, could be affected by the amount of flue gas that is recirculated to the kiln, the temperature of the kiln, and / or other approaches. It is also possible to supplement flue gas 10 with an inert gas such as nitrogen, with CO2, or other gases, to obtain a carrier gas for the feed rC (stream 01) that minimizes carbon losses in favor of producing treated rC. Air can be added in some cases. Optionally, the added gas is preheated.

[0074] Approaches seeking to reduce or minimize carbon gasification increase the carbon amounts recovered in the treated rC. Thus, in some implementations, the treated rC can contain at least about 80 wt % of the carbon present in the feed rC. In examples, the amount of carbon in the treated rC is at least about 85, at least about 90 or at least about 95 wt% of the carbon present in the starting rC.Docket: 2024701

[0075] The process can include additional steps. As already noted, treated rC and / or the ZnO product can be quenched. Quenching operations also can be conducted on stream 09, to lower its temperature before release to the atmosphere. In many cases, stream 09 is scrubbed or otherwise treated before being exhausted, to remove harmful emissions such as, for instance, sulfur-containing compounds (SO2 and / or other SOx species).

[0076] The continuous process described herein can be automated. For instance, a computer controller (optional component 200 in the Figure) can be employed to regulate flows, monitor or adjust kiln and / or burner operating parameters, analyze and / or act upon sensor data, and so forth. The controller can be provided with interfaces for input and output information, using technology known in the art, for example.

[0077] Simulations of the process described herein, using representative values of 1300 °C kiln temperatures, 270% burner PC, and 0.2 recycle ratio, showed that ZnS can be completely removed. The loss of rC carbon content according to this model was about 12%. The treated rC product contained about 12 wt% residual ash (in the form of SiCh) and was generated at about 0.8 kg / kg yield relative to the weight of the feed rC.

[0078] Further aspects of the disclosure relate to properties of the treated rC obtained by the deashing process described herein. In many cases, characterization of the treated rC and, if desired, of the rC introduced to the kiln via stream 01, can be conducted by methods developed for CBs.

[0079] As known, CBs can be characterized by their Brunauer-Emmett-Teller (BET) surface area, measured, for example, according to ASTM D6556; by their oil adsorption number (OAN), determined, for instance, according to ASTM D 2414; by their statistical thickness surface areas (STSAs), a property that can be determined by ASTM D 6556; by their iodine adsorption number (I2NO), determined by ASTM D 1510. For a given CB, it may also be of interest, in some cases, to specify the ratio of its STSA to its BET surface area (STSA:BET ratio).

[0080] The primary particle size of a CB can be determined according to ASTM D 3849.Docket: 2024701

[0081] Iron content and / or total metal (cobalt, chromium, copper, manganese, nickel) can be measured by inductively coupled plasma (ICP) techniques with a sample being digested following a furnace ashing method according to ASTM D8371.

[0082] The pH of CBs can be measured according to ASTM D 1512.

[0083] CBs can be characterized by their density (kg / m3), e.g., bulk density and / or tap density. Tap density can be measured on 10 grams samples using a Varian Tap Density Instrument with a 5- to 30-minute run time.

[0084] Some CB properties relate to the physical form of a given CB. The CB particle size in dispersions, for example, can be determined by particle size distribution (PSD) techniques using a Horiba LA-950V2 Particle Size Analyzer and its software and / or a differential centrifugal sedimentation (DCS) method. In the Horiba LA-950V2 method, a small amount of dispersion is diluted with water, then added to the instrument to achieve 85-88% laser transmittance before measurement. In many cases, PSD techniques will measure both aggregates and agglomerates (referred herein as particles).

[0085] Disk centrifuge photosedimentometry (DCP) techniques can be employed to evaluate the mean particle diameter, e.g., mean CB particle size. In one approach, DCP measurements employ CPS Instruments, Model DC24000 and an ultrasonic processor (Branson, Model 450D with a half-inch probe tip). Dispersion samples were prepared by sonicating compositions each containing 0.02g carbon black and 50ml dispersion fluid (75% v / v water, 25% v / v ethanol and 0.05%w / v Triton X100 surfactant) at an amplitude of 60% for ten minutes. Instrument settings included a particle density of 1.86; a refractive index of 1.84; an absorptivity of 0.85; and a non-sphericity of 1.0. Run conditions included a disc speed of 24K rpm; a gradient of 24 to 8% sucrose in deionized water (14.4ml); a gradient density of 1.045; a gradient refractive index of 1.345; a gradient viscosity of 1.25 cP; and a calibration standard of 237nm polystyrene (density 1.385).

[0086] Comparing the input rC (stream 01) with the treated rC (stream 03) is expected to reveal changes that render the treated rC more suitable for a specific end-use application than the starting rC.Docket: 2024701

[0087] In some embodiments, the treated rC is used as a substitute for the entire amount of CB typically employed in the application. In other embodiments, . the treated rC described herein is combined with virgin CB to form a blend. Thus, depending on the end use, the treated rC described herein can be combined with about 0 to about 99 wt% virgin CB.. In one example, the blend contains less than about 50 wt% virgin CB, e.g., less than about 40, less than about 30, less than about 20, or less than about 10 wt %. In other examples the weight amount of virgin CB in the blend is higher than the weight amount of treated rC.

[0088] The treated rC, optionally milled and / or pelletized, can be added to an elastomeric composition to prepare elastomeric materials, e.g., for tire and / or other rubber applications, at any loading suitable for the particular end use application. . The elastomer can be selected from natural rubbers, functionalized natural rubbers, styrene-butadiene rubbers, functionalized styrene-butadiene rubbers, polybutadiene rubbers, functionalized polybutadiene rubbers, polyisoprene rubbers, ethylene-propylene copolymers, isobutylene-based rubbers, polychloroprene rubbers, nitrile rubbers, hydrogenated nitrile rubbers, polysulfide rubbers, polyacrylate elastomers, fluoroelastomers, perfluoroelastomers, and blends thereof.

[0089] In some cases, often for tires or other rubber applications, the elastomeric composite containing treated rC also contains fresh or virgin CB. Any suitable relative weight amounts of treated rC, optionally milled and / or pelletized, to virgin CB can be employed. Moreover, there is no limitation to the properties (BET, OAN, etc.) characterizing the virgin CB. Ratios employed, and / or the selection of a particular CB can be determined by routine experimentation, prior experience with the particular end-use, or other factors.

[0090] The present disclosure includes the following aspects / embodiments / features in any order and / or in any combination:1. The present disclosure, in part, relates to a process for deashing reclaimed carbon, the process comprising:combining a feed reclaimed carbon containing zinc sulfide and a recycled flue gas at conditions sufficient to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; andDocket: 2024701recycling at least a portion of the flue gas as the recycled flue gas, wherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed reclaimed carbon.2. The present disclosure, in part, relates to a process for deashing reclaimed carbon containing zinc sulfide, the process comprising:(a) reducing the zinc sulfide present in a feed reclaimed carbon to form zinc vapors and a treated reclaimed carbon, said treated reclaimed carbon containing at least 80% by weight of the carbon present in the feed reclaimed carbon;(b) oxidizing the zinc vapors to form zinc oxide and a flue gas; and(c) recycling at least a portion of the flue gas to step (a).3. The present disclosure, in part, relates to a process for deashing reclaimed carbon, the process comprising:heating a feed reclaimed carbon containing zinc sulfide in the presence of a recycled flue gas to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; and recycling at least a portion of the flue gas as the recycled flue gas, wherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed carbon.4. The present disclosure, in part, relates to a process for deashing reclaimed carbon, the process comprising:reacting a feed reclaimed carbon containing zinc sulfide with products of combustion at conditions sufficient to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; and recycling at least a portion of the flue gas to provide the products of combustion, wherein the treated reclaimed carbon has a carbon contain that is at least 80% by weight of the carbon content present in the feed carbon.5. The present disclosure, in part, relates to a process for deashing reclaimed carbon, the process comprising:Docket: 2024701reacting a feed reclaimed carbon and a hot carrier gas to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas, wherein, at least a portion of the flue gas is recycled to provide at least a portion of the hot carrier gas, andwherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed carbon.6. The process of any preceding or following embodiment / feature / aspect, wherein the feed reclaimed carbon is pre-milled.7. The process of any preceding or following embodiment / feature / aspect, wherein a carbon content in the treated reclaimed carbon is at least about 90 % by weight of the carbon content present in the feed reclaimed carbon.8. The process of any preceding or following embodiment / feature / aspect, wherein the feed reclaimed carbon contains ash in an amount within a range from about 10 to about 30 % by weight.9. The process of any preceding or following embodiment / feature / aspect, wherein the feed reclaimed carbon contains zinc sulfide in an amount within a range from about 5 to about 12 % by weight.10. The process of any preceding or following embodiment / feature / aspect, wherein the treated reclaimed carbon contains zinc in an amount no greater than about 10 % by weight.11. The process of any of the preceding claims, wherein the treated reclaimed carbon contains zinc in an amount within a range from about 0 to about 2 % by weight.12. The process of any of the preceding claims, wherein at least about 50 % to 100 % by weight of the zinc present in the feed reclaimed carbon is removed.Docket: 202470113. The process of any of the preceding claims, wherein ash present in the feed reclaimed carbon is reduced by at least about 10% by weight.14. The process of any preceding or following embodiment / feature / aspect, further comprising milling the treated reclaimed carbon.15. The process of any preceding or following embodiment / feature / aspect, further comprising pelletizing the treated reclaimed carbon.16. The process of any of any of the preceding claims, further comprising combining the treated reclaimed carbon with a virgin carbon black to form a blend.17. The process of claim 16, further comprising granulating the blend.18. The process of any preceding or following embodiment / feature / aspect, wherein a zinc product generated from combusting the zinc vapors with oxygen contains zinc in an amount of at least 60 % by weight.19. The process of any preceding or following embodiment / feature / aspect, further comprising quenching the treated reclaimed carbon and / or the zinc oxide.20. The process of any preceding or following embodiment / feature / aspect, further comprising quenching and / or scrubbing the flue gas that is not recycled.21. The process of any preceding or following embodiment / feature / aspect, wherein the recycled flue gas provides from about 5 % to about 30 % of the energy needed to reduce the zinc sulfide present in the feed reclaimed carbon.22. The process of any preceding or following embodiment / feature / aspect, wherein the zinc vapors are oxidized using a primary combustion that is greater than 100 %.Docket: 202470123. The process of any of the preceding claims, wherein the volume fraction of the recycled flue gas is within a range from about 0.05 to about 0.5 of the flue gas.24. The process of any preceding or following embodiment / feature / aspect, wherein the recycled flue gas has a temperature lower than the temperature needed to vaporize ZnS.25. The process of any preceding or following embodiment / feature / aspect, further comprising heating the recycled flue gas to a temperature sufficient to vaporize ZnS.26. The process of any preceding or following embodiment / feature / aspect, wherein the temperature is within a range from about 1100 to about 1500°C.27. The process of any of the preceding claims, wherein the process is continuous.28. The process of any preceding or following embodiment / feature / aspect, wherein the process is conducted in a Waeltz rotary kiln.29. The process of any preceding or following embodiment / feature / aspect, further comprising separating the treated rC from a hot off gas containing the zinc vapors.30. The process of any preceding or following embodiment / feature / aspect, wherein the hot offgas further comprises nitrogen gas, carbon monoxide and / or sulfur-containing gases.31. The process of any preceding or following embodiment / feature / aspect, further comprising separating the zinc oxide from the flue gas.32. The process of any preceding or following embodiment / feature / aspect further comprising splitting the flue gas into a recycle stream and a purge stream.Docket: 202470133. The process of any preceding or following embodiment / feature / aspect, wherein the flue gas contains carbon dioxide.34. The process of any preceding or following embodiment / feature / aspect, wherein the flue gas contains oxygen in an amount not greater than about 12 mole %.35. The process of any preceding or following embodiment / feature / aspect, further comprising controlling a composition and / or quantity of the recycled flue gas.36. The process of any preceding or following embodiment / feature / aspect, wherein a carbon gasification process is reduced by controlling a composition and / or quantity of the recycled flue gas.37. The process of any preceding or following embodiment / feature / aspect, wherein at least one step of the process is computer-controlled.38. The process of any preceding or following embodiment / feature / aspect, further comprising incorporating the treated reclaimed carbon in an elastomeric composition.39. A treated reclaimed carbon prepared by the process of any preceding or following embodiment / feature / aspect.40. An elastomeric composition comprising the treated reclaimed carbon of any preceding or following embodiment / feature / aspect.41. The elastomeric composition of any preceding or following embodiment / feature / aspect, further comprising a virgin carbon black.

[0091] Embodiments of the disclosure are further illustrated in the following nonlimiting example.Docket: 2024701Example

[0092] Simulations were performed using Aspen Plus vl2 and the Solids property method recommended for pyrometallurgical processes. Species simulated as solids were C (graphite), ZnS (wurtzite), ZnO, and SiO2 (quartz). All other species listed in the tables below were simulated as conventional species. rC was modeled as 80 wt% C, 10 wt% SiO2, and 10 wt% ZnS. The adjustable parameters in the process were: (1) the kiln temperature, (2) burner primary combustion (PC), and (3) flue gas recycle ratio. In the example, the simulation assumed a 100% solids recovery (complete recovery of ZnO) and used a kiln temperature of 1300°C, a 270% burner PC, and a 0.2 recycle ratio.

[0093] The rotary kiln 112 was simulated using a combination of an isothermal Gibbs reactor and adiabatic flash (solid-gas separation). The burner 114 was simulated using an adiabatic Gibbs reactor. The ZnO filter 118 was simulated using an adiabatic flash. The recycle 10 and purge 09 were simulated using a splitter with a specified split fraction.

[0094] Presented in Tables 1A and IB are the characteristics of the streams shown in the Figure.Table 1AStream # Units 01 02 03 04 05 Description rC feed Kiln Treated Kiln Burner air output rC offgasFlow kmol / h 69.3 88.9 60.5 28.4 89.2 Flow Nm3 / h - 1992 - 635.8 2000 Flow ac m3 / h - 3710 - 2885 2212 Flow kg / h 1000 1671 806.6 864.4 2574 Temperature °C 25 1300 25 950 25 Pressure atma 1 1 1 1 1

[0095] Docket: 2024701Table IBStream # Units 06 07 08 09 10 Description Burner Burner ZnO Purge Carrier output flue gas product gas recycle Flow kmol / h 111.9 110.9 1.03 88.7 22.2 Flow NnrVh 2509 2486 - 2989 497.1 Flow ac m3 / h 13767 13587 - 10869 2717 Flow kg / h 3439 3355 83.5 2684 671 Temperature °C 1220 1220 25 1220 1220 Pressure atma 1 1 1 1 1

[0096] The composition of the various streams is shown in Tables 1C and ID.Table 1CStream # Units 01 02 03 04 05 Description rC feed Kiln Treated Kiln Burner air output rC offgasC mol% 96.1 6.2 97.2 - - CO mol% - 10.2 - 31.9 - CO2 mol% - <0.01 - <0.01 - O2 mol% - - - - 21.0 N2 mol% - 19.8 - 62.1 79 ZnS mol% 1.48 - - - - ZnO mol% - - - - - Zn mol% - 1.15 - 3.6 -Docket: 2024701cs mol% - 0.68 - 2.1 - cos mol% - 0.08 0.26 - SO2 mol% - - - - - SiO2mol% 2.40 1.87 2.75 - -

[0097] Table IDStream # Units 06 07 08 09 10 Description Burner Burner ZnO Purge Carrier output flue gas product gas recycle C mol% - - - - - CO mol% <0.01 <0.01 - <0.01 <0.01 CO2 mol% 8.7 8.8 - 8.8 8.8 O2 mol% 10.5 10.6 - 10.6 10.6 N2 mol% 78.7 79.5 - 79.5 79.5 ZnS mol% - - - - - ZnO mol% 0.92 - 100 - - Zn mol% <0.01 <0.01 - <0.01 <0.01 CS mol% - - - - - cos mol% - - - - - SO2 mol% 1.15 1.16 - 1.16 1.16 SiO2mol% - - - - -

[0098] As seen in these tables, the temperature of the recycle stream 10 is somewhat (about 80°C) lower than the approximate 1300°C required to vaporize ZnS in kiln 112. AsDocket: 2024701described above, additional heat can be provided, using various techniques, to reach the required reaction temperature. As also seen, the treated rC (stream 03) is substantially free of ZnS and produced in an overall 80.7 wt% yield relative to the starting rC (stream 01).Comparing the compositions and flow rates of streams 01 and 03 further shows that the treated rC contains about 88 wt% of the carbon present in the starting rC, i.e., that only about 12 wt% of carbon is lost during the process.

[0099] Temperatures of the treated rC and ZnO products (streams 03 and 08, Tables 1A and IB, respectively) assume a quenching operation that brings these materials to ambient temperatures.

[0100] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Further, the singular forms and the articles "a", "an" and "the" are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms: includes, comprises, including and / or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groupsthereof. Further, it will be understood that when an element, including component or subsystem, is referred to and / or shown as being connected or coupled to another element, it can be directly connected or coupled to the other element or intervening elements may be present.[ ooioi] It will be understood that although terms such as “first” and “second” are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, an element discussed could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present disclosure.

[0102] Unless otherwise defined, all terms (including 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. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent withDocket: 2024701their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0103] While this disclosure has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the disclosure encompassed by the appended claims.

Claims

Docket: 2024701CLAIMSWhat is claimed is:

1. A process for deashing reclaimed carbon, the process comprising:combining a feed reclaimed carbon containing zinc sulfide and a recycled flue gas at conditions sufficient to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; and recycling at least a portion of the flue gas as the recycled flue gas, wherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed reclaimed carbon.

2. A process for deashing reclaimed carbon containing zinc sulfide, the process comprising: (a) reducing the zinc sulfide present in a feed reclaimed carbon to form zinc vapors and a treated reclaimed carbon, said treated reclaimed carbon containing at least 80% by weight of the carbon present in the feed reclaimed carbon;(b) oxidizing the zinc vapors to form zinc oxide and a flue gas; and(c) recycling at least a portion of the flue gas to step (a).

3. A process for deashing reclaimed carbon, the process comprising:heating a feed reclaimed carbon containing zinc sulfide in the presence of a recycled flue gas to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; and recycling at least a portion of the flue gas as the recycled flue gas, wherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed carbon.

4. A process for deashing reclaimed carbon, the process comprising:reacting a feed reclaimed carbon containing zinc sulfide with products of combustion at conditions sufficient to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas; andDocket: 2024701recycling at least a portion of the flue gas to provide the products of combustion, wherein the treated reclaimed carbon has a carbon contain that is at least 80% by weight of the carbon content present in the feed carbon.

5. A process for deashing reclaimed carbon, the process comprising:reacting a feed reclaimed carbon and a hot carrier gas to produce zinc vapors and a treated reclaimed carbon;combusting the zinc vapors with oxygen to produce zinc oxide and a flue gas, wherein, at least a portion of the flue gas is recycled to provide at least a portion of the hot carrier gas, andwherein the treated reclaimed carbon contains at least 80% by weight of the carbon present in the feed carbon.

6. The process of any of the preceding claims, wherein the feed reclaimed carbon is premilled.

7. The process of any of the preceding claims, wherein a carbon content in the treated reclaimed carbon is at least about 90 % by weight of the carbon content present in the feed reclaimed carbon.

8. The process of any of the preceding claims, wherein the feed reclaimed carbon contains ash in an amount within a range from about 10 to about 30 % by weight.

9. The process of any of the preceding claims, wherein the feed reclaimed carbon contains zinc sulfide in an amount within a range from about 5 to about 12 % by weight.

10. The process of any of the preceding claims, wherein the treated reclaimed carbon contains zinc in an amount no greater than about 10 % by weight.

11. The process of any of the preceding claims, wherein the treated reclaimed carbon contains zinc in an amount within a range from about 0 to about 2 % by weight.Docket: 202470112. The process of any of the preceding claims, wherein at least about 50 % to 100 % by weight of the zinc present in the feed reclaimed carbon is removed.

13. The process of any of the preceding claims, wherein ash present in the feed reclaimed carbon is reduced by at least about 10% by weight.

14. The process of any of the preceding claims, further comprising milling the treated reclaimed carbon.

15. The process of any of the preceding claims, further comprising pelletizing the treated reclaimed carbon.

16. The process of any of any of the preceding claims, further comprising combining the treated reclaimed carbon with a virgin carbon black to form a blend.

17. The process of claim 16, further comprising granulating the blend.

18. The process of any of the preceding claims, wherein a zinc product generated from combusting the zinc vapors with oxygen contains zinc in an amount of at least 60 % by weight.

19. The process of any of the preceding claims, further comprising quenching the treated reclaimed carbon and / or the zinc oxide.

20. The process of any of the preceding claims, further comprising quenching and / or scrubbing the flue gas that is not recycled.

21. The process of any of the preceding claims, wherein the recycled flue gas provides from about 5 % to about 30 % of the energy needed to reduce the zinc sulfide present in the feed reclaimed carbon.Docket: 202470122. The process of any of the preceding claims, wherein the zinc vapors are oxidized using a primary combustion that is greater than 100 %.

23. The process of any of the preceding claims, wherein the volume fraction of the recycled flue gas is within a range from about 0.05 to about 0.5 of the flue gas.

24. The process of any of the preceding claims, wherein the recycled flue gas has a temperature lower than the temperature needed to vaporize ZnS.

25. The process of claim 24, further comprising heating the recycled flue gas to a temperature sufficient to vaporize ZnS.

26. The process of claim 25, wherein the temperature is within a range from about 1100 to about 1500°C.

27. The process of any of the preceding claims, wherein the process is continuous.

28. The process of any of the preceding claims, wherein the process is conducted in a Waeltz rotary kiln.

29. The process of any of the preceding claims, further comprising separating the treated rC from a hot off gas containing the zinc vapors.

30. The process of claim 29, wherein the hot offgas further comprises nitrogen gas, carbon monoxide and / or sulfur-containing gases.

31. The process of any of the preceding claims, further comprising separating the zinc oxide from the flue gas.Docket: 202470132. The process of any of the preceding claims further comprising splitting the flue gas into a recycle stream and a purge stream.

33. The process of any of the preceding claims, wherein the flue gas contains carbon dioxide.

34. The process of any of the preceding claims, wherein the flue gas contains oxygen in an amount not greater than about 12 mole %.

35. The process of any of the preceding claims, further comprising controlling a composition and / or quantity of the recycled flue gas.

36. The process of any of the preceding claims, wherein a carbon gasification process is reduced by controlling a composition and / or quantity of the recycled flue gas.

37. The process of any of the preceding claims, wherein at least one step of the process is computer-controlled.

38. The process of any of the preceding claims, further comprising incorporating the treated reclaimed carbon in an elastomeric composition.

39. A treated reclaimed carbon prepared by the process of any of claims 1 through 38.

40. An elastomeric composition comprising the treated reclaimed carbon of claim 39.

41. The elastomeric composition of claim 40, further comprising a virgin carbon black.

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