System and method for processing materials by sulfur pretreatment

Abstract

According to an example aspect, there is provided a system for processing materials, comprising: a chamber configured to contain a material to be processed; and one or more gas sources configured to provide a sulfur species; wherein the chamber is configured to form a sulfidizing agent by at least partially disassociating and / or ionizing the sulfur species 5 with an electric arc and / or plasma source, and perform a sulfidation reaction on the material with the sulfidizing agent.

Description

SYSTEM AND METHOD FOR PROCESSING MATERIALS BY SULFUR PRETREATMENTFIELD

[0001] The present teachings relate generally to the system and method for processing materials and, more particularly, to sulfur pretreatment for usage with sulfidation in order to extract metals from feedstocks.BACKGROUND AND OBJECTS

[0002] The process of separating a target material from a feedstock is important during the production of metals and other materials. Target materials must be separated from bulk or impure feedstocks that may be extracted from a mined ore, recycled waste, or industrial byproduct. A variety of separation approaches are currently employed for metals manufacturing, including hydrometallurgical and pyrometallurgical methods.

[0003] Hydrometallurgical separations are used for various material processing systems due to their high selectivity. Selectivity refers to the effectiveness of the separation process to target an individual component from a multicomponent feedstock. Hydrometallurgical approaches include but are not limited to leaching; dissolution and selective precipitation; dissolution, solvent extraction and precipitation; and dissolution, ion exchange and precipitation. These and similar processing schemes enable the highly targeted separation and recovery of individual materials out of a variety of convoluted mineral and industrial feedstocks. However, hydrometallurgical separations generally require large quantities of water, acids, and organic solvents, making processing and waste treatment challenging as well as costly due to the high volumes of liquids employed. Additionally, spent acids are often neutralized with limestone, generating greenhouse gas emissions.

[0004] Pyrometallurgical separations generally rely on treating a feedstock material at high temperatures to extract a target component via roasting, melting, distillation, or phase separation. One such approach is selective carbothermic reduction, where a target metal is reduced from a mixed oxide feedstock to produce the target liquid metal and a liquid slag containing oxide impurities. The slag and the metal are generally immiscible with oneanother, allowing the two liquids to be separated. This approach may generate direct greenhouse gas emissions and exhibits limited selectivity for some metals.

[0005] Alternatively, solid-gas pyrometallurgical processing can be employed for separations. For example, calcination roasting can be used to isolate calcium oxide (lime) from calcium carbonate (limestone). Another roasting process is halogenation, where a mixed metal oxide is reacted with a chlorinating or fluorinating agent, generally in the presence of carbon, to selectively form a halide of the target metal. Distillation is often utilized to separate one halide from another or from unreacted oxide. Both calcination and halogenation generally exhibit significant environmental impacts in the form of greenhouse gas production from either the reaction chemistry or fuel burned to heat the furnace. The safe processing and handling of chlorinating and fluorinating agents can be costly at industrial scales due to their high toxicity.

[0006] Alternative separation processes are desirable to enable clean, sustainable, and targeted metal extraction and recovery from ore or recycled feedstocks. One such processing approach relies on sulfidation to selectively isolate individual components from a mixed oxide feedstock as sulfides.

[0007] These target sulfides are readily separated from impurity oxides via a wide range of benign physical and chemical methods. During sulfidation, a mixed metal oxide is treated with a solid, liquid, or gaseous material containing sulfur (e.g., a sulfidizing agent). Molecular sulfur gas is generally preferred for sulfidation due to its low cost. By controlling how aggressively the sulfur containing material reacts with the mixed oxide feedstock (a phenomena called sulfidation potential), one or more components of the mixed oxide feedstock may be selectively converted into sulfides.

[0008] Sulfidation may also be used to separate materials from other feedstocks, including but not limited to sulfates, carbonates, phosphates, selenides, tellurides, arsenides, oxysulfides, sulfides, oxyhalides, and sulfosalts. When molecular sulfur is utilized for the sulfidation process, high gas flow rates, carbon additives, reducing additives, halide additives, or other metal compound additives must be utilized to selectively sulfidize some of the more stable oxides. These additional additives can introduce new impurities into the system which must be further separated. Halide additives in particular can lead to the formation of halide sulfur compounds, many of which are greenhouse gases. Additionally, asystem which requires a high gas flow rate increases the need for a sulfur recirculation system to be implemented.

[0009] Known systems and methods for separating materials suffer from issues relating to pollution, energy use, and difficulty in extracting certain metal oxides. They also have limitations in their ability to accommodate impurities in the feed material as well as those introduced by recycling, which has been driven by concerns over supply as well as environmental sustainability. Therefore, it would be beneficial to have an alternative system and method for control of sulfidation potential and selectivity during sulfidation reactions.SUMMARY

[0010] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0011] According to a first aspect, there is provided a system for processing materials, comprising:- a chamber configured to contain a material to be processed; and- one or more gas sources configured to provide a sulfur species;wherein the chamber is configured to form a sulfidizing agent by at least partially disassociating and / or ionizing the sulfur species with an electric arc and / or plasma source, and perform a sulfidation reaction on the material with the sulfidizing agent.

[0012] In one embodiment, the gas source(s) comprise(s) a tuyere, a hollow electrode, a lance, thermal decomposition of a first metal sulfide, thermal decomposition of a second metal sulfide, or a combination thereof. In another embodiment, the chamber may have a plurality of sources of gas. The ratio of the sulfur species introduced through each source of gas may be configured to achieve a predetermined ratio of ionized and / or disassociated sulfur species in the vicinity of a gas source, and / or a predetermined average ratio of ionized and / or disassociated sulfur species throughout the chamber, although not limited thereto.

[0013] In one embodiment, the gas source(s) is / are generated from a liquid boiling within a tuyere, a hollow electrode, or a lance, or at the interface between a tuyere, a hollow electrode, or a lance and the chamber.

[0014] In some embodiments, the sulfidizing agent is created by ionizing a predetermined ratio of the sulfur species. In other embodiments, the sulfidizing agent is created by disassociating a predetermined ratio of the sulfur species.

[0015] In some embodiments, the chamber comprises at least one of an AC arc furnace, DC arc furnace, submerged arc furnace, shaft furnace, rotary kiln, multihearth furnace, rotary hearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter.

[0016] In another embodiment, the sulfur species introduced to the chamber by the source of gas consists of gaseous elemental sulfur, gaseous hydrogen sulfide, or a combination thereof. In yet another aspect, the plasma source utilized to generate the sulfidizing agent includes at least one of an inert species such as argon or nitrogen and a reactive species such as hydrogen, natural gas, or biogas. In some embodiments, the material with which the sulfidizing agent reacts may be, but is not limited to an oxide of iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, or calcium.

[0017] According to a second aspect, there is provided a method of processing materials, comprising:- providing a chamber having one or more inlets;- adding a gas containing a sulfur species and a material to be processed to the chamber via the inlet(s);- contacting at least a portion of the sulfur species with an electric arc and / or plasma source to disassociate and / or ionize the sulfur species, to form a sulfidizing agent before the inlet(s), at the inlet(s) or inside the chamber; and- combining at least a portion of the sulfidizing agent with the material contained within the chamber to produce a sulfide, oxy sulfide, sulfate or a metal.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 A is a schematic diagram of one embodiment of sulfur disassociation in accordance with at least some embodiments.

[0019] FIG. IB is a schematic diagram of one embodiment of sulfur ionization in accordance with at least some embodiments.

[0020] FIG. 2 is a schematic view of another embodiment of sulfur ionization and / or disassociation occurring in a chamber in accordance with at least some embodiments.

[0021] FIG. 3 is a schematic view of another embodiment of sulfur ionization and / or disassociation occurring in a rotary kiln in accordance with at least some embodiments.

[0022] FIG. 4 is a schematic view of sulfur ionization and / or disassociation occurring in a shaft or multihearth furnace in accordance with at least some embodiments.

[0023] FIG. 5A is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Al2O3utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0024] FIG. 5B is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of CaO utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0025] FIG. 5C is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of CoO utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0026] FIG. 5D is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of CrS utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0027] FIG. 5E is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of Fe3O4utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0028] FIG. 5F is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of HfO2utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0029] FIG. 5G is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of MgO utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0030] FIG. 5H is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of MnO utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0031] FIG. 5I is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of MoO3utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0032] FIG. 5J is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of Nb2O5utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0033] FIG. 5K is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of NiO utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0034] FIG. 5L is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of SiO2utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0035] FIG. 5M is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Ta2O5utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0036] FIG. 5N is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of TiO2utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0037] FIG. 5O is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of V2O3utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0038] FIG. 5P is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of WO3utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0039] FIG. 5Q is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of ZrO2utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.

[0040] FIG. 6A is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Al2O3utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0041] FIG. 6B is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of CaO utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0042] FIG. 6C is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of CoO utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0043] FIG. 6D is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of Cr2O3utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0044] FIG. 6E is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Fe3O4utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0045] FIG. 6F is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of HfO2utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0046] FIG. 6G is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of MgO utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0047] FIG. 6H is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of MnO utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0048] FIG. 6I is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of MoO3utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0049] FIG. 6J is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Nb2O5utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0050] FIG. 6K is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of NiO utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0051] FIG. 6L is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of SiO2utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0052] FIG. 6M is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of Ta2O5utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0053] FIG. 6N is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of TiO2utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0054] FIG. 6O is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of V2O3utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0055] FIG. 6P is a graph of (PSX / PSO2)critversus temperature for sulfidation reactions of WO3utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0056] FIG. 6Q is a graph of (Psx / Pso2)crit versus temperature for sulfidation reactions of ZrO2utilizing molecular and atomic sulfur species in accordance with at least some embodiments.

[0057] FIG. 7A is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of Al2O3of various reactant to product ratios in accordance with at least some embodiments.

[0058] FIG. 7B is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of CaO of various reactant to product ratios in accordance with at least some embodiments.

[0059] FIG. 7C is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of CoO of various reactant to product ratios in accordance with at least some embodiments.

[0060] FIG. 7D is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of Cr2O3of various reactant to product ratios in accordance with at least some embodiments.

[0061] FIG. 7E is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of Fe3O4of various reactant to product ratios in accordance with at least some embodiments.

[0062] FIG. 7F is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of HfO2of various reactant to product ratios in accordance with at least some embodiments.

[0063] FIG. 7G is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of MgO of various reactant to product ratios in accordance with at least some embodiments.

[0064] FIG. 7H is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of MnO of various reactant to product ratios in accordance with at least some embodiments.

[0065] FIG. 71 is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of MoO3of various reactant to product ratios in accordance with at least some embodiments.

[0066] FIG. 7J is a graph of (PsI Pso2)crit versus temperature for sulfidation reactions of Nb2O5of various reactant to product ratios in accordance with at least some embodiments.

[0067] FIG. 7K is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of NiO of various reactant to product ratios in accordance with at least some embodiments.

[0068] FIG. 7L is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of SiO2of various reactant to product ratios in accordance with at least some embodiments.

[0069] FIG. 7M is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of Ta2O5of various reactant to product ratios in accordance with at least some embodiments.

[0070] FIG. 7N is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of TiO2of various reactant to product ratios in accordance with at least some embodiments.

[0071] FIG. 70 is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of V2O3of various reactant to product ratios in accordance with at least some embodiments.

[0072] FIG. 7P is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of WO3of various reactant to product ratios in accordance with at least some embodiments.

[0073] FIG. 7Q is a graph of (Ps / PSO2)critversus temperature for sulfidation reactions of ZrO2of various reactant to product ratios in accordance with at least some embodiments.

[0074] FIG. 8 is a graph of (PS2 / PSO2)critversus temperature for sulfidation reactions of various metal oxides in accordance with at least some embodiments.

[0075] FIG. 9 is a graph of (Ps / PSO2)critversus temperature of sulfidation reactions for various metal oxides in accordance with at least some embodiments.

[0076] FIG. 10 is a graph of (PS(+) / PSO2)critversus temperature (1000–1500 °C) for sulfidation reactions of various metal oxides in accordance with at least some embodiments.

[0077] FIG.11 is a graph of (PS(+) / PSO)critversus temperature (1500-2000 °C) for sulfidation reactions of various metal oxides in accordance with at least some embodiments.

[0078] FIG. 12 is a graph of (PS(+) / PSO)critversus temperature (2000-3000 °C) for sulfidation reactions of various metal oxides in accordance with at least some embodiments.

[0079] FIG. 13 is a graph of (PS / PSO)critversus temperature for sulfidation reactions of Cr2O3and Fe3O4utilizing molecular, atomic, or ionized sulfur species in accordance with at least some embodiments.DETAILED DESCRIPTIONDefinitions

[0080] For purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description with unnecessary detail.

[0081] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. The use of "first", "second," etc. for different features / components of the present disclosure are only intended to distinguish the features / components from other similar features / components and not to impart any order or hierarchy to the features / components.

[0082] Recitations of numerical ranges by endpoints include all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Where a range of values is "greater than", "less than", etc., of a particular value, that value is included within the range.

[0083] Any direction referred to herein, such as "top," "bottom," "left," "right," "upper," "lower," "above," below," and other directions and orientations are described herein for clarity in reference to the figures and are not to be limiting of an actual device or system or use of the device or system. Many of the devices, articles, or systems described herein may be used in a number of directions and orientations.

[0084] In the present description, the terms “reactor” and ’’chamber” can be used interchangeably.Embodiments

[0085] Oxides can be difficult to separate from one another, motivating the use of alternative processing chemistries. Sulfidation can be used to separate oxides by selectively converting them to sulfides. Sulfidation of oxides was previously envisioned to occur in certain machines, such as rotary kilns, fluidized beds, multihearth furnaces, shaft furnaces, and converters. The process of sulfidation utilizes a sulfur species, such as but not limited to molecular sulfur gas and hydrogen sulfide, which requires higher gas flow rates, carbon additives, halide additives, or other metal compound additives to successfully sulfidize more stable oxides.

[0086] Sulfidation followed by physical or chemical separation provides a promising pathway to reduce the environmental impact of separating metal oxides. However, current methods that utilize carbon additives to control sulfidation potential may still exhibit direct greenhouse gas emissions.

[0087] Pretreatment of sulfidizing agents to form atomic, disassociated, or ionized sulfur containing gases is a desirable approach.

[0088] According to an aspect, there is provided a system for processing materials, comprising:- a chamber configured to contain a material to be processed; and- one or more gas sources configured to provide a sulfur species;wherein the chamber is configured to form a sulfidizing agent by at least partially disassociating and / or ionizing the sulfur species with an electric arc and / or plasma source, and perform a sulfidation reaction on the material with the sulfidizing agent.

[0089] In the present system, sulfidation potential during sulfidation reactions may be controlled by at least partially disassociating and / or ionizing sulfur gas or another sulfidizing agent in a pretreatment step prior to its use in the sulfidation reaction. Dissociation and / or ionization of a sulfidizing agent prior to use in the sulfidation reaction enables higher sulfidation potentials to be achieved without a carbothermically driven sulfur reflux (CDSR). This provides a carbon-free alternative to the CDSR approach. Dissociation and / or ionization of a sulfidizing agent can be achieved by contacting it with an electric arc and / orplasma source prior to use in the sulfidation process. Unlike in the approaches where the number of sulfur atoms in a sulfur gas molecule are controlled by temperature or pressure at thermodynamic equilibrium, disassociation and / or ionization of sulfidizing agents using an electric arc and / or plasma source allows a much greater range of nonequilibrium conditions to be achieved in sulfidizing agents.

[0090] In an example, the system for processing materials comprises:- a chamber containing a material to be processed; and- one or more gas sources providing a sulfur species;wherein the chamber is configured to form a sulfidizing agent by at least partially disassociating and / or ionizing the sulfur species with an electric arc and / or plasma source, and perform a sulfidation reaction on the material with the sulfidizing agent.

[0091] According to an embodiment, the material comprises an oxide of iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, and / or calcium.

[0092] According to an embodiment, plasma source comprises at least one of an inert species, such as argon or nitrogen, and a reactive species, such as hydrogen, natural gas, or biogas.

[0093] Plasma processing for metals production has generally been explored in the context of hydrogen reduction to reduce mineral or chemical feedstock compounds to metals. Hydrogen molecules may be disassociated and / or ionized using or into a plasma source to form atomic or ionized hydrogen. Atomic and ionized hydrogen are both substantially stronger reductants than molecular hydrogen at a given temperature and pressure. However, hydrogen reduction exhibits very different chemical behavior and requires very different processing considerations than sulfidation. Plasma sources have not been utilized to pretreat sulfidizing agents via disassociation and / or ionization to increase sulfidation potential in this way. Likewise, sulfur containing plasma has not been considered as a sulfidizing agent for sulfidation reactions for mineral processing.

[0094] The gas source(s) can be connected to the chamber or generated outside the chamber.

[0095] According to an embodiment, the gas source(s) comprise(s) a tuyere, a hollow electrode, a lance, thermal decomposition of a first metal sulfide, thermal decomposition of a second metal sulfide, or a combination thereof.

[0096] According to an embodiment, the gas source may be generated from a liquid boiling within a tuyere, a hollow electrode, or a lance. The liquid may include, but is not limited to elemental sulfur, carbon disulfide, or any combination thereof. When the liquid is at least partially comprised of elemental sulfur, various additives may optionally be included within sulfur, including but not limited to hydrogen sulfide, carbon monoxide, carbon dioxide, carbonyl sulfide, organic species, liquefaction agents, or viscosity modulating agents.

[0097] According to an embodiment, the gas source may be generated from a liquid boiling at the interface between a tuyere, a hollow electrode, or a lance and the chamber configured to form a sulfidizing agent by disassociating and / or ionizing the sulfur species with an electric arc and / or plasma source. The liquid may include, but is not limited to elemental sulfur, carbon disulfide, or some combination thereof. When the liquid is at least partially comprised of elemental sulfur, various additives may optionally be included within the sulfur, including but not limited to hydrogen sulfide, carbon monoxide, carbon dioxide, carbonyl sulfide, organic species, liquefaction agents, or viscosity modulating agents.

[0098] According to an embodiment, the chamber comprises two or more sources of gas and the ratio of the sulfur species introduced through each gas source is configured to achieve a predetermined ratio of ionized and / or disassociated sulfur species in the chamber.

[0099] According to an embodiment, the sulfur species consists of gaseous elemental sulfur, gaseous hydrogen sulfide, or a combination thereof.

[0100] According to an embodiment, the disassociating and / or ionizing of the sulfur species comprises ionizing a predetermined ratio of the sulfur species.

[0101] According to an embodiment, the disassociating and / or ionizing of the sulfur species comprises disassociating a predetermined ratio of the sulfur species.

[0102] In some examples, a sulfidizing agent is produced by pretreatment of at least a portion of sulfur gas that enters a chamber containing a feed material. At least a portion of the sulfur gas may be disassociated and / or ionized into atomic or ionized sulfur duringpretreatment, although not limited thereto. The resulting sulfidizing agent may be more reactive with an oxide than the original sulfur species within the sulfur gas.

[0103] Disassociation and / or ionization may also be used to increase the permeability of the sulfidizing agent in a solid materials feedstock. In some examples, this may have several processing efficiency and efficacy benefits, including enabling larger feedstock particle sizes to be utilized for sulfidation, reducing the need for fine grinding, reducing the minimum solid feedstock residence time, or decreasing the sulfidation operation temperature. By controlling the ratio of disassociated and / or ionized sulfur to molecular sulfur gas at controlled flowrates, with a given additive blend one can selectively sulfidize an oxide of a feed material containing multiple metal oxides. A model-based controller can be added to control sulfur feed rates and arc power or plasma source or generator power to produce a target disassociation or ionization ratio.

[0104] According to an embodiment, the chamber comprises at least one of an AC arc furnace, DC arc furnace, submerged arc furnace, rotary kiln, multihearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter.

[0105] The chamber(s) where sulfidation occurs may be located within a furnace such as an AC arc furnace, DC arc furnace, submerged arc furnace, rotary kiln, multihearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter, although not limited thereto. The furnace may comprise additional chambers for further sulfidation, refining, reduction or other smelting operations. In some examples, the overall system comprises two or more furnaces. In some examples, the one or more furnaces may contain a vacuum chamber or an additional vacuum unit.

[0106] The one or more furnaces may also contain single or multiple tapholes, tuyeres, plasma sources and plasma generators in different locations and heights for different sulfidation, calcination, decomposition, or reduction agents, although not limited thereto. Various partitioning designs between chambers and / or furnaces may be utilized, including tap-based or with walls for liquid to flow over into a subsequent processing chamber. Various roof types may also be employed, including refractory or water-cooled metals. One skilled in the art appreciates the different designs that may be used to employ the present teachings.

[0107] In examples where an arc furnace is utilized, the furnace may contain multiple electrodes in series, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or more, and each of one or more chambers (in a single arc furnace or different arc furnaces) may each have its own series of electrodes. In one example, the one or more arc furnaces may be AC and / or DC powered.

[0108] Inflow of sulfur species via the gas source(s) may be controlled using a feedback loop. In some examples, a control system may contain a gas control valve and a flowmeter connected to an automation system. The controller may leverage a proportional, proportional-integral, proportional- integral-derivative, or internal model control algorithm to control the flowrate. In other examples, more advanced control algorithms and models may be used to increase the level of control. Parameters such as gas compositions sampled from the furnace, process temperature, conductivity, and arc behavior may be utilized to inform the extent of sulfur consumption and sulfidation reactor conversion.

[0109] In some examples, the chamber may have two or more gas sources. The gas sources may be distributed spatially throughout.

[0110] In some examples where one or more gas sources is the thermal decomposition of a metal sulfide contained within the chamber, the metal sulfide is added to the chamber prior to any feed material.

[0111] In other examples, the metal sulfide which will undergo thermal decomposition and the feed material are mixed together and added to the chamber simultaneously.

[0112] At least a portion of the sulfur species may be ionized and / or disassociated to form the sulfidizing agent prior to interaction with the feed material within the chamber.

[0113] According to an embodiment, the chamber comprises two or more gas sources, wherein at least one gas source is configured to produce the disassociation and / or ionization of the sulfur species at a different extent than the other(s).

[0114] In some examples where the chamber may have two or more gas sources or inlets, different gas sources into the chamber may have different extents of ionization and / or disassociation of sulfur species. Regulation of the ratio of ionized to disassociated to molecular sulfur from different gas sources and the bulk ratio of ionized to disassociated tomolecular sulfur in the system may be used to control the sulfidation potential in the chamber.

[0115] According to an embodiment, an extent of the disassociation and / or ionization of the sulfur species is configured to be regulated by adjusting the ratio of a power of the electric arc or a power of the plasma source to a feed rate of the sulfur species.

[0116] Operating with different ratios of ionized to disassociated to molecular sulfur at different gas sources or inlets can also locally tune the sulfidation potential or create a bulk or average sulfidation potential in the system. The extent of ionization and / or disassociation of sulfur species can be regulated through adjusting the ratio of the plasma source or generator power to the sulfur feed rate or arc power to the sulfur feed rate.

[0117] In some examples, addition of inert gases can be used to control the plasma source or arc temperature in order to adjust the ratio of ionized to disassociated to molecular sulfur. Once a metal oxide has been sulfidized and converted into a sulfide, oxysulfide, or sulfate of the metal, the resulting product can be reduced into a purified metal. The remaining metal oxides in the feed material can be selectively sulfidized in the same chamber or they can be moved to another chamber for further sulfidation or processing.

[0118] In some examples, gas composition samples from the furnace and a process temperature may be measured to monitor the extent of the sulfidation reaction and determine if the sulfidation process is complete for a target component of the feedstock. Some embodiments may use these and other measured process values to populate a model-based controller which can predict the degree of sulfidation and automatically trigger the next processing phase. In some embodiments, this controller may leverage proportional, proportional-integral, or proportional-integral-derivative, or internal model-based algorithms.

[0119] The various embodiments, examples and variants disclosed here in connection with the system apply mutatis mutandis to the method.

[0120] According to an aspect, there is provided a method of processing materials, comprising:- providing a chamber having one or more inlet(s);- adding a gas containing a sulfur species and a material to be processed to the chamber via the inlet(s);- contacting at least a portion of the sulfur species with an electric arc and / or plasma source to disassociate and / or ionize the sulfur species, to form a sulfidizing agent before the inlet(s), at the inlet(s) or inside the chamber; and- combining at least a portion of the sulfidizing agent with the material contained within the chamber to producing a sulfide, oxy sulfide, sulfate or a metal.

[0121] The sulfur species and the material to be processed can be added to the chamber via different inlets. For example, the sulfur species can be added via a gas inlet and the material to be processed can be added via a chamber inlet. Then, the sulfidizing agent can be formed before the gas inlet, at the gas inlet or inside the chamber.

[0122] According to an embodiment, the gas source(s) is / are generated from a liquid boiling within a tuyere, a hollow electrode, or a lance, or at the interface between a tuyere, a hollow electrode, or a lance and the chamber.

[0123] According to an embodiment, the gas is added from one or more gas sources comprising at least one of a tuyere, a hollow electrode, a lance, thermal decomposition of a first metal sulfide, thermal decomposition of a second metal sulfide, or a combination thereof.

[0124] According to an embodiment, the gas is added from two or more sources, wherein the ratio of the sulfur species introduced through each source of gas is configured to achieve a predetermined ratio of ionized and / or disassociated sulfur species in the chamber.

[0125] According to an embodiment, the disassociating and / or ionizing of the sulfur species comprises ionizing a predetermined ratio of the sulfur species.

[0126] According to an embodiment, the disassociating and / or ionizing of the sulfur species comprises disassociating a predetermined ratio of the sulfur species.

[0127] According to an embodiment, the chamber comprises at least one of an AC arc furnace, DC arc furnace, submerged arc furnace, rotary kiln, multihearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter.

[0128] According to an embodiment, the gas consists of gaseous elemental sulfur, gaseous hydrogen sulfide, or a combination thereof.

[0129] According to an embodiment, the plasma source comprises at least one of an inert species such as argon or nitrogen and a reactive species such as hydrogen, natural gas, or biogas.

[0130] According to an embodiment, the material comprises an oxide of iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, and / or calcium.

[0131] According to an embodiment, the sulfur species is added to the chamber prior to the material.

[0132] According to an embodiment, the sulfur species and the material are mixed together and added to the chamber simultaneously.DETAILED DESCRIPTION OF THE DRAWINGS

[0133] The present teachings are described more fully hereinafter with reference to the accompanying drawings, in which the present embodiments are shown. The following description is presented for illustrative purposes only and the present teachings should not be limited to these embodiments.

[0134] It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

[0135] FIGS. 1A and IB illustrate the effect of ionization and disassociation on a sulfur species 102. The sulfur species 102 comprises, for example, molecular sulfur Sx, where X is a range from 2 to 8, hydrogen sulfide (H2S), or a combination thereof. Fig. 1 A illustrates how disassociation of the sulfur gas results in atomic sulfur 104. Fig. IB illustrates how ionization of the sulfur gas results in ionized sulfur 106. The process of ionization and / or disassociation may be completed by subjecting at least a portion of the sulfur species 102 to a heat source in order to form a sulfidizing agent.

[0136] The sulfidizing agent may be formed from ionizing, disassociating, or a combination thereof of the molecular sulfur species of the sulfur species 102, although not limited thereto. In some examples, this heat source may include, but is not limited to, an electric arc from an electrode or plasma source from a plasma generator. A variety of plasmagenerators may be utilized, including but not limited to, electric arcs, plasma torches, or microwave systems. The sulfidizing agent can be reacted with feed material to selectively sulfidize oxides in an effort to provide a metal sulfide which can be reduced to a purified metal. Both ionized and atomic sulfur may be more reactive with oxides during sulfidation than the original sulfur species 102.

[0137] Referring now to FIG. 2 shown is one example of a chamber 200 with an electrode 208, a tuyere 210, and a plasma generator 212. The chamber 200 is designed to contain and sulfidize a feed material 220 utilizing a sulfidizing agent comprising a gaseous sulfur species 202. The sulfur species 202 may consist of molecular sulfur, atomic sulfur, ionized sulfur or a combination thereof, although not limited thereto. The feed material 220 may be a solid, liquid, or a mix of both phases during sulfidation. The feed material 220 may include at least one metal oxide or gangue. The chamber 200 may include a chamber inlet 204 to introduce the feedstock 220. In some examples, the feed material 220 contains multiple metal oxides. The metal within the feed material 220 may include, but is not limited to, iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, and / or calcium.

[0138] In order to sulfidize the feed material 220, a sulfur species 202 may be introduced into the chamber 200 through one or more gas sources. The sulfur species 202 can be added before, after, or during the addition of feed material 220 into the chamber 200. Once added, the sulfur species may undergo ionization, dissociation, or both before reacting with the feed material 220.

[0139] The gas source may be designed to introduce a sulfur species 202 into the chamber 200. The gas source may include, but is not limited to, a hollow electrode 208, a tuyere 210, a plasma generator 212, thermal decomposition of a metal sulfide contained within the chamber 200, or any other source capable of adding molecular sulfur gas to the chamber 200. The sulfur species 202 may be introduced either directly as a gas, or as a liquid that boils within a hollow electrode 208, a tuyere 210, or lance, or as a liquid that boils at the interface between a hollow electrode 208, a tuyere 210, or lance, and the chamber 200. Chamber 200 may include a chamber outlet 206 to extract gas from the chamber. Furthermore, the chamber may include a tapping hole 214 that can be used to extract sulfidized feed material from the chamber.

[0140] Another example of a chamber 300 is described with reference to FIG. 3. The chamber 300 is similar to the chamber 200 described in FIG. 2, but discloses an adaptation for a rotary kiln. The chamber 300 includes a gas inlet 302 wherein a sulfur species 304 containing molecular sulfur gas, hydrogen sulfide or a combination thereof is introduced into the chamber. In the illustrated example, disassociation and / or ionization of at least a portion of the introduced sulfur species 304 occurs while it is passing through the gas inlet 302. In some examples, the ionization and / or disassociation occurs within the gas inlet 302. In other examples, the ionization and / or disassociation occur at a tip 308 of the gas inlet 302. In some examples, the sulfur species 304 may be introduced as a liquid that boils within the gas inlet 302 or at the tip 308 of the gas inlet. Feed material is introduced into the chamber 300 through the feed inlet 310. During operation the feed material progresses from the feed inlet 310 towards the gas inlet 302, where it reacts with the sulfidizing agent to selectively sulfidize metal oxides within the feed material.

[0141] Another example of a chamber 400 is described with reference to FIG. 4. The chamber 400 is similar to the chamber 200 described in FIG, 2, but discloses an adaptation for a shaft or multihearth furnace. Feed material is introduced into the system through the feed inlet 410. A sulfur species 402 comprising a sulfur containing gas is introduced into the bottom of the chamber 400 through the gas inlet 404. In some examples, the sulfur species 402 may be introduced as a liquid that boils within the gas inlet 404 or at the tip 408 of the gas inlet. In the illustrated example, disassociation and / or ionization of at least a portion of the introduced sulfur species 402 occurs while it is passing through the gas inlet 404. In some examples, ionization and / or disassociation occurs within the gas inlet 404. In other examples, ionization and / or disassociation occurs at a tip 408 of the gas inlet 404.

[0142] The sulfidizing agent comprising the produced atomic or ionized sulfur may contact any feed material contained within the chamber 400. The sulfidizing agent may rise up through the chamber 400 in a counter current flow to any feed material. As the sulfidizing agent and feed material come into contact metal oxides within the feed material are selectively sulfidized into a sulfide, oxy sulfide, of sulfate of the metal.EXAMPLES

[0143] An important sulfur to sulfur dioxide pressure ratio (PxI Pso2)crit where X is a range from 1 to 8, can be thermodynamically computed when the system is at thermal equilibrium for any metal oxide, sulfate, oxysulfide, or sulfide which is being sulfidized.However, solution effects, mass transport behavior, kinetic rates, and reactor design lead to deviations between the thermodynamically derived (PS / PSO)critpressure ratio, and the operationally required (PS / PSO)critpressure ratio for sulfidation of a target metal compound product.

[0144] SO2 as represented in the (PS / PSO)critpressure ratio is usually not present at the start of the reaction and is generated in the system as the sulfidation reaction proceeds. Therefore, while a thermodynamic (PS / PSO)critratio may be calculated, it often differs in value to the operationally required (PS / PSO)critwhen kinetic and mass transport effects are considered for the sulfidation reaction. Kinetic and mass transport parameters such as oxide feedstock particle size, surface area, feedstock packing density, or state of matter (solid or liquid) may lead to deviations between thermodynamic and operational (7sx / Pso2)crit ■

[0145] Operational (PS / PSO)critin the chamber may be monitored via gas sampling lines that connect to a gas sensor, including but not limited to, infrared or mass spectrometer sensors. In some examples, desired operational (PSxI Pso^crtt ratios may be maintained through control of the inlet flowrate of the sulfidizing agent, its space time or space velocity in the chamber, and the ratio of ionized to disassociated to molecular species in the sulfidizing agent. Some examples, may employ a process controller utilizing these and other measured process values in order to leverage proportional, proportional-integral, or proportional -integral-derivative, or internal model -based algorithms for model -based control of (PSxI Pso^crtt in the system.

[0146] The higher the pressure ratio of (PS / PSO)crit-. the more aggressive the sulfidation conditions need to be for the reaction to proceed at thermodynamic equilibrium. The pressure ratio (PS / PSO)critmay refer to a pressure ratio of atomic sulfur to sulfur dioxide, (PsI Pso2)cri.t~. in some examples, or a pressure of ratio of ionized sulfur to sulfur dioxide, (Ps(+) I Pso2)cri.t~. in others, respectively. Operationally Psx / Pso^crtt ratios closer to unity are generally easier to achieve and maintain within the chamber without additional carbon or oxygen addition.

[0147] Conventional sulfidation processes rely on molecular sulfur gas Sx, where x is a range from 2 to 8. In one embodiment (PSx / Pso2)cri.t corresponds to (Ps2, / Pso2)cri.t fordiatomic S2. In some embodiments S2 is pretreated by the system in order to disassociate molecular sulfur, Sx, into atomic sulfur, S, or ionize molecular sulfur, Sx, to ionized sulfur, S(+).Example 1

[0148] Referring to FIGS. 5A-5Q, shown are graphs of thermodynamic (PS / PSO)critversus temperature for sulfidation reactions of various metal oxides utilizing molecular, atomic, or ionized sulfur species. FIGS. 5A-5Q depict the difference in the pressure ratio between (PS2I PSo2)cnt, (PsI Pso2)crit, and (Ps(+) / PSo2)cnt sulfur at a constant pressure of 1 atm. In principle, the sulfidation reaction can be run at any pressure, yet system pressures close to 1 atm are preferred. As can be seen in the FIGS. 5A-5Q typically (PS2IPSo2)cnt > (PsI Pso^crtt > (Ps(+) I Pso^crtt at temperatures below the thermodynamic equilibrium ionization or disassociation temperature of Sx.

[0149] As discussed above, the lower the pressure ratio (PSxI Pso^crtt is, the lessaggressive the sulfidation environment needs to be, and the simpler it is to reach and maintain a chosen operational (Psx / Pso2)crit within the chamber. This may indicate that pretreatment of the molecular sulfur gas via disassociation or ionization generally enables the reaction to sulfidize a metal oxide into an oxysulfide, sulfate, or sulfide under less aggressive sulfidation conditions and at lower temperatures. In some examples, this can make the selective sulfidation, desulfidation, or oxide-sulfide-sulfate- oxysulfide anion exchange of one metal compound versus another easier to achieve. In other examples, it can lead to a loss of selectivity in the sulfidation, desulfidation, or oxide-sulfide-sulfate-oxysulfide anion exchange of one metal compound versus another. Some examples may employ molecular, atomic, and ionized sulfur species to adjust the selectively of the sulfidation reaction as needed.Example 2

[0150] Referring to FIGS. 6A-6Q, shown are graphs of thermodynamic (PS / PSO)critversus temperature for sulfidation reactions of various metal oxides using molecular and atomic sulfur species to illustrate differences between a thermodynamically derived pressure ratio of a system using molecular sulfur, Sx, and atomic sulfur, S. For most metal oxides the sulfidation environment desired for processing may be less aggressive whenusing atomic sulfur species in place of molecular sulfur species. This is indicated by the lower pressure ratios shown in comparison to a system utilizing only molecular sulfur species as the sulfidizing agent.Example 3

[0151] Referring to FIGS. 7A-7Q, shown are graphs of a thermodynamically derived (PsI Pso2)crit versus temperature for sulfidation of metal oxides with various activity ratios of reactants and products. Variations in the feedstock and product activity lead to sharp variations in (PSx / Pso2)crit- This highlights that the operational (PS / PSO)critwith real system mixing effects and nonidealities may be drastically different from pure state theoretical thermodynamic (PS / PSO)crit-

[0152] A less aggressive sulfidation environment may be desirable in systems where the target material to be sulfidized exhibits a lower thermodynamic (Psx / Pso2)crit- However, variations between operational and thermodynamic (PS / PSO)critmayarisedue to an aggregation of kinetic, mass transport, solution mixing, and reactor operational effects that are difficult if not impossible to determine from scientific theory alone. For two oxides, one may exhibit a higher thermodynamic (Psx / Pso2)critand lower operation (PS / PSO)critthan another or vice versa.

[0153] In some examples, control of the ratio of ionized to disassociated to molecular sulfidizing agents can be utilized to maintain sufficient sulfidation potentials in order to target a particular operational (PS / PSO)critwhile avoiding losses of sulfidation selectivity due to overly aggressive sulfidation conditions. For examples where continuous feeding of oxide feedstocks and removal of sulfidized products from the reaction chamber is possible, including but not limited to, electric arc furnaces, multihearth reactors, or kilns, different steady state conditions may be achieved in different regions of the chamber. Therefore, the steady state operational (Psx / Pso2)crit may vary at different points in the chamber, motivating either cocurrent or countercurrent flow of sulfidizing agents and sulfidation products.Example 4

[0154] Referring to FIG. 8, shown is a graph of thermodynamically derived pressure ratio, (Ps2, 1 Pso2)crit versus temperature for sulfidation of various metal oxides at a totalpressure of 1 atm. Species with a lower (PS2 / Pso2)crit have a stronger thermodynamic affinity toward sulfidation and may be sulfidized using less aggressive sulfidation gas atmospheres.Example 5

[0155] In FIG. 9 a graph of thermodynamically derived (Ps / Pso2)crit versus temperature for sulfidation reactions of various metal oxides is shown. As can be seen in comparison to FIG. 8, the pressure ratios of FIG. 9 range from IO'10to 106meaning that a less aggressive and easier to maintain sulfidation environment is required when using atomic sulfur species, S.Example 6

[0156] Referring to FIGS. 10-12, shown are graphs of thermodynamically derived (Ps(+) / Pso2)cnt versus temperature of sulfidation reactions utilizing ionized sulfur for various metal oxides. Ionizing sulfur results in a lower pressure ratio and therefore a more energy efficient and stable system. FIG. 10 depicts a temperature range from 1000-1500 °C, whereas FIG. 11 covers 1500-2000 °C, and FIG. 12 covers 2000-3000 °C. FIG. 10 depicts the lowest pressure ratios. As the temperature within the chamber rises a more aggressive sulfidation environment may be required. Systems utilizing ionized sulfur species depict the lowest pressure ratios. This is further shown by FIG. 13.

[0157] FIG. 13 depicts a graph of (PS / PSO)critversus temperature for sulfidation reactions of Cr2O3and Fe3O4utilizing molecular, atomic, or ionized sulfur species. The sulfidation reactions of FIG. 13 that utilize ionized sulfur species have the lowest pressure ratios over the entire temperature range. In this figure, thermodynamically derived (Ps2IPso2)crit, (PsI Pso^crit, and (Ps(+) / Pso^crtt are compared for the sulfidation of 2 pure iron oxide and chromium oxide at a total pressure of 1 atm. An operational ~Psx / Pso22of 0.1 is depicted. A variety of operational values of -PSx / PSo2however may be employed depending on the feedstock chemistry, kinetic effects, mass transport effects, and reactor specific phenomena.

[0158] Sulfidation of pure iron oxide and chrome oxide is thermodynamically 2spontaneous in the system if a plotted (,~Psx / Pso^crit is graphically below the plotted2~psx / Pso operation- Based on differences in operation (PS2I PSo2)cnt, (PsIpso2)cnt,2and (Ps(+) / PSo2)crit, at a given temperature and ~psx / pso2operation, sulfidation of iron oxide and chromium oxide species may be thermodynamically spontaneous for both species, thermodynamically nonspontaneous for both species, or thermodynamically spontaneous for only iron oxide depending whether S2, S, or S(+) is the sulfidation agent. Similar thermodynamic selectivity comparisons may be made for any combination of oxide, oxysulfide, sulfate, or sulfide compounds.

[0159] Variations in solution effects, mass transport, kinetics, and reactor-specific behavior are currently difficult if not impossible to predict from scientific theory alone and lead to the system adjusting variations between PSx / Pso^crtt and the actual 2^PSX / pso2) operation during operation.

[0160] While (PSxIpso2)crit has been considered in the context of oxide sulfidations, similar calculations and analysis may be conducted for other potential sulfidation feedstocks, including but not limited to sulfates, carbonates, phosphates, selenides, tellurides, arsenides, oxysulfides, sulfides, oxyhalides, and sulfosalts. Similar process control levers described herein for ionization or disassociation of sulfidizing agents for oxides may be applied to other sulfidation feedstocks, including but not limited to sulfates, carbonates, phosphates, selenides, tellurides, arsenides, oxysulfides, sulfides, oxyhalides, and sulfosalts.

[0161] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0162] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention.

[0163] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwiseexplicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.REFERENCE SIGNS LIST200, 300, 400 chamber102, 202, 304, 402 sulfur species104 atomic sulfur106 ionized sulfur204 chamber inlet206 chamber outlet208 electrode210 tuyere212 plasma generator214 tapping hole220 feed material302, 404 gas inlet308, 408 tip310, 410 feed inlet

Claims

1. CLAIMS:

1. A system for processing materials, comprising:- a chamber configured to contain a material to be processed; and - one or more gas sources configured to provide a sulfur species; wherein the chamber is configured to form a sulfidizing agent by at least partially disassociating and / or ionizing the sulfur species with an electric arc and / or plasma source, and perform a sulfidation reaction on the material with the sulfidizing agent.

2. The system according to claim 1, wherein the gas source(s) is / are generated from a liquid boiling within a tuyere, a hollow electrode, or a lance, or at the interface between a tuyere, a hollow electrode, or a lance and the chamber.

3. The system according to claim 1, wherein the gas source(s) comprise(s) a tuyere, a hollow electrode, a lance, thermal decomposition of a first metal sulfide, thermal decomposition of a second metal sulfide, or a combination thereof.

4. The system according to any one of the preceding claims, wherein the chamber comprises two or more sources of gas and the ratio of the sulfur species introduced through each gas source is configured to achieve a predetermined ratio of ionized and / or disassociated sulfur species in the chamber.

5. The system according to any one of the preceding claims, wherein the disassociating and / or ionizing of the sulfur species comprises ionizing a predetermined ratio of the sulfur species.

6. The system according to any one of the preceding claims, wherein the disassociating and / or ionizing of the sulfur species comprises disassociating a predetermined ratio of the sulfur species.

7. The system according to any one of the preceding claims, wherein the chamber comprises at least one of an AC arc furnace, DC arc furnace, submerged arc furnace,rotary kiln, multihearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter.

8. The system according to any one of the preceding claims, wherein the sulfur species consists of gaseous elemental sulfur, gaseous hydrogen sulfide, or a combination thereof.

9. The system according to any one of the preceding claims, wherein the plasma source comprises at least one of an inert species, such as argon or nitrogen, and a reactive species, such as hydrogen, natural gas, or biogas.

10. The system according to any one of the preceding claims, wherein the material comprises an oxide of iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, and / or calcium.

11. The system according to any one of the preceding claims, wherein the chamber comprises two or more gas sources, wherein at least one gas source is configured to produce the disassociation and / or ionization of the sulfur species at a different extent than the other(s).

12. The system according to any one of the preceding claims, wherein an extent of the disassociation and / or ionization of the sulfur species is configured to be regulated by adjusting the ratio of a power of the electric arc or a power of the plasma source to a feed rate of the sulfur species.

13. A method of processing materials, comprising:- providing a chamber having one or more inlets;- adding a gas containing a sulfur species and a material to be processed to the chamber via the inlet(s);- contacting at least a portion of the sulfur species with an electric arc and / or plasma source to disassociate and / or ionize the sulfur species, to form a sulfidizing agent before the inlet(s), at the inlet(s) or inside the chamber; andcombining at least a portion of the sulfidizing agent with the material contained within the chamber to produce a sulfide, oxysulfide, sulfate or a metal.

14. The method of claim 13, wherein the gas source(s) is / are generated from a liquid boiling within a tuyere, a hollow electrode, or a lance, or at the interface between a tuyere, a hollow electrode, or a lance and the chamber.

15. The method of claim 13, wherein the gas is added from one or more gas sources comprising at least one of a tuyere, a hollow electrode, a lance, thermal decomposition of a first metal sulfide, thermal decomposition of a second metal sulfide, or a combination thereof.

16. The method according to any one of the preceding claims 13-15, wherein the gas is added from two or more gas sources, wherein the ratio of the sulfur species introduced through each source of gas is configured to achieve a predetermined ratio of ionized and / or disassociated sulfur species in the chamber.

17. The method according to any one of the preceding claims 13-16, wherein the disassociating and / or ionizing of the sulfur species comprises ionizing a predetermined ratio of the sulfur species.

18. The method according to any one of the preceding claims 13-17, wherein the disassociating and / or ionizing of the sulfur species comprises disassociating a predetermined ratio of the sulfur species.

19. The method according to any one of the preceding claims 13-18, wherein the chamber comprises at least one of an AC arc furnace, DC arc furnace, submerged arc furnace, rotary kiln, multihearth furnace, fluidized bed reactor, flash smelter, electroslag refiner, vacuum arc remelter, or converter.

20. The method according to any one of the preceding claims 13-19, wherein the gas consists of gaseous elemental sulfur, gaseous hydrogen sulfide, or a combination thereof.

21. The method according to any one of the preceding claims 13–20, wherein the plasma source comprises at least one of an inert species such as argon or nitrogen and a reactive species such as hydrogen, natural gas, or biogas.

22. The method according to any one of the preceding claims 13–21, wherein the material comprises an oxide of iron, nickel, chromium, molybdenum, manganese, cobalt, silicon, zirconium, hafnium, titanium, vanadium, niobium, tantalum, tungsten, aluminum, magnesium, and / or calcium.

23. The method according to any one of the preceding claims 13–22, wherein the sulfur species is added to the chamber prior to the material.

24. The method according to any one of the preceding claims 13–22, wherein the sulfur species and the material are mixed together and added to the chamber simultaneously.

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