392results about "Iron oxides/hydroxides" patented technology

The invention provides anti-ionizing radiation powder with a core-shell heterogeneous gradient structure and a preparation method and application of the anti-ionizing radiation powder, and belongs to the field of radiation protection.The preparation method of the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure comprises the following steps that high-atomic-number metal salt is added into deionized water, aging, washing, drying and primary calcination are conducted in sequence, and the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure is obtained; a core layer is obtained; the core layer and low-atomic-number metal salt are added into deionized water, aging, washing, drying and primary calcination are sequentially conducted, and preliminary wrapping powder with the high-atomic-number metal core layer wrapped by low-atomic-number metal is obtained; and adding the preliminarily wrapped powder and rare earth salt into deionized water, and sequentially performing aging, washing, drying, primary calcining, secondary calcining, airflow crushing and air rotation purging to obtain the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure. Through cooperation of the core-shell heterostructure, the high-atomic-number oxide, the low-atomic-number oxide and the multi-element rare earth element, the shielding performance of the material is remarkably improved.

The invention relates to a method for recovering metal cations from wet-process phosphoric acid, and belongs to the technical field of wet-process phosphoric acid. The technical problem to be solved by the invention is to provide a method for recovering metal cations from wet-process phosphoric acid. The method comprises the steps of extraction, washing 1, reverse extraction, metal ion recovery, washing 2 and the like. The specific reverse extraction method is adopted, the metal cations are recovered from the wet-process phosphoric acid, various metal ions can be effectively separated, the recovery rate of all metal elements is high, and the product value is high. And the associated metal elements in the wet-process phosphoric acid can be classified and recycled by adopting one stripping agent, the method is simple and low in cost, and the recycled associated metal elements can be effectively separated and utilized in a high-quality mode.

The invention relates to an electrolytic fluorine-making nickel-containing waste electrolyte treatment method which comprises the following steps: heating a fluorine-making electrolytic cell to 80-95 DEG C, completely melting the electrolyte, standing for layering, and taking out the colorless electrolyte on the upper layer; excessive fluorine gas is introduced into the electrolytic cell, and ferrous ions in the remaining electrolyte are converted into iron ions; electrolyte in the electrolytic bath is guided into an anti-corrosion container, deionized water is added into the anti-corrosion container, and the electrolyte is completely dissolved; adjusting the pH value of the solution in the container to 3-4, fully precipitating, and carrying out solid-liquid separation to obtain a solid A and a filtrate A; adjusting the pH value of the filtrate A to 9-11, fully precipitating, and carrying out solid-liquid separation to obtain a solid B and a filtrate B; and adjusting the ion molar ratio of F <-> to K < + > in the filtrate B to be 2: 1, then carrying out evaporative crystallization, and drying obtained crystals to obtain products of potassium hydrogen difluoride and potassium fluoride. The waste electrolyte can be effectively treated, and resources are efficiently recycled and reutilized.

The invention relates to the technical field of micro-nano motors, in particular to a preparation method and application of a micro-nano motor for improving oil reservoir exploitation. Due to the wheel shape of the micro-nano motor and the hydrophobic modification effect, the micro-nano motor can move in a high-viscosity oil reservoir environment in oil reservoir exploitation. Under the action of a magnetic field, the micro-nano motor can controllably move in a complex three-dimensional core environment, and the size of the micro-nano motor can be reduced when the micro-nano motor encounters a narrower pore throat, so that the micro-nano motor can smoothly pass through the pore throat. When the micro-nano motor makes contact with crude oil drops, the micro-nano motor can carry the oil drops to move and carry the oil drops to a high-permeability area of the oil reservoir, and the motor carrying the oil drops is extracted to the ground along with displacement fluid, so that the recovery rate of the oil reservoir is increased. Meanwhile, the micro-nano motor can be recycled for multiple times.

The invention discloses a chlorobenzene wastewater continuous stripping purification recovery device and an implementation method, the chlorobenzene wastewater continuous stripping purification recovery device comprises an aeration tank, an alkali water washing system, an acid water washing system, an acid-base neutralization system and a ferric hydroxide separation system, the aeration tank is connected with the alkali water washing system, the acid water washing system is connected with the alkali water washing system, and the acid water washing system is connected with the ferric hydroxide separation system. The acid-base neutralization system is connected with the alkali-water washing system, the acid-water washing system and the ferric hydroxide separation system, and the alkali-water washing system and the acid-water washing system are both in two-stage steam stripping, and have the following advantages: alkali washing water and acid washing water generated in the chlorobenzene production process are subjected to two-stage nitrogen steam stripping, so that the content of organic matters is greatly reduced; ferric hydroxide is generated through neutralization of acid-alkali wastewater, the total amount of the wastewater is reduced, then the ferric hydroxide reacts with hydrochloric acid in the pickling water to generate ferric trichloride, hydrochloric acid is neutralized, the neutralization product ferric hydroxide is consumed, the wastewater amount is reduced, and recycling of wastewater resources is achieved.

The invention relates to a method and a system for preparing a battery metal oxide precursor through nitrate spray pyrolysis. The method comprises the following steps: preparing a metal nitrate mixed solution; atomizing and spraying the metal nitrate mixed solution into a reaction furnace, and performing pyrolysis through different heating temperature zones in the reaction furnace to obtain a metal oxide mixture and high-temperature flue gas; the high-temperature flue gas is subjected to waste heat recovery treatment and then enters a regeneration device to be recovered, and regenerated nitric acid is obtained; the metal oxide mixture is subjected to secondary heating at the bottom of the reaction furnace. The metal oxide precursor is prepared through spray pyrolysis, and compared with a traditional coprecipitation calcination process, the method is more economical and lower in operation cost; and different heating temperature zones are adopted for pyrolysis, so that the application range is wider, and the device can be suitable for metal nitrate at different pyrolysis temperatures.

Provided are cobalt ferrite particles having a micrometer-order average particle diameter and similar particle diameters. The cobalt ferrite particles are obtained by a method for producing cobalt ferrite particles, including performing a thermal treatment on an aqueous solution containing a divalent iron salt and a divalent cobalt salt stabilized by a complexing agent (ferrite precursor).

The invention discloses a method for extracting and recovering metal elements in a lithium battery by using a chlorination method, and belongs to the technical field of lithium battery recovery, the method comprises the following steps: step 1, roasting a lithium battery positive plate to remove organic matters, and stripping to remove aluminum foil to obtain electrode material powder; step 2, placing the electrode material powder on a carrier of a Joule heating device, carrying out thermal shock treatment in a chlorine atmosphere, and heating and chlorinating in stages in the treatment process; step 3, desublimating gas generated after chlorination in each stage; and 4, adding the desublimated solid in each stage into deionized water, mixing, adding a sodium carbonate aqueous solution, collecting the precipitate, washing, and drying to obtain a metal salt product. Based on the characteristics that Joule heat can rapidly heat and accurately control the temperature, by combining the difference between the temperature of chlorination reaction of different metal oxides and the gasification temperature of a chlorinated product, staged gasification desublimation treatment is achieved, different metal chlorides are obtained, and accurate and efficient purification is achieved.

The invention discloses a device and a method for regenerating a powdery iron oxyhydroxide desulfurizer and purifying sulfur, and the device and the method are characterized in that invalid iron oxyhydroxide is completely reduced into a ferrous oxide and ferrous sulfide after sulfide is added, the reaction of an iron compound is enhanced through ultrasound and stirring, and the separation of the iron compound and the sulfur is promoted. Further fully aerating to fully oxidize the ferrous iron to generate new iron oxyhydroxide; at the moment, the iron oxyhydroxide is in a completely dispersed state, the single particle size is not higher than 1 micron, and small flocs with the particle size of 0-5 microns are formed in laminar water; the surface of the sulfur has hydrophobicity, and the sulfur is gathered to generate hydrophobic self-flocculation, so that large flocs with the particle size of 30-300 microns are formed in the laminar water; the mixture is flushed by water flows with different flow speeds, the iron oxyhydroxide with small particle size is flushed out at a certain flow speed, and the sulfur with large particle size is suspended in the grading pipe, so that the regeneration of the iron oxyhydroxide desulfurizer and the purification of the sulfur are realized.

The invention relates to a method for recycling aluminum, iron and lithium from waste lithium iron phosphate batteries. The method comprises the following steps: firstly, separating a positive electrode material of a waste battery cell, removing a binder through high-temperature treatment, adding the positive electrode material into a NaOH solution and a viscous liquid cosolvent, finally stirring and dissolving, neutralizing and adjusting the pH value through sulfuric acid, and precipitating and recovering aluminum; then sulfuric acid is matched with hydrogen peroxide, residual filter residues are stirred and dissolved, the pH value is adjusted in multiple steps, iron and lithium are precipitated respectively, and Fe (OH) 3 and Li2CO3 precipitates are obtained in sequence; the viscous liquid cosolvent disclosed by the invention is prepared from 1-aminoethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imine salt and boric acid powder; the recovery rate of aluminum, lithium and iron is high, the recovery cost is low, and the economic value is high.

Provided is a hydrogen sulfide removing agent that can be stably used while maintaining hydrogen sulfide removing ability equivalent to that of a hydrogen sulfide removing agent comprising an amorphous iron oxyhydroxide. This iron oxyhydroxide-based hydrogen sulfide removing agent contains amorphous iron oxyhydroxide and a crystalline component. The content of the amorphous iron oxyhydroxide is not less than the content of the crystalline component.

The invention discloses a method for extracting and recovering metal elements in lithium batteries using a chlorination method, which belongs to the technical field of lithium battery recovery. The method comprises the following steps: step 1, calcining the positive electrode sheet of the lithium battery to remove organic matter, and peeling off the aluminum foil to obtain electrode material powder; step 2, placing the electrode material powder on a carrier of a Joule heat device, and performing a thermal shock treatment under a chlorine atmosphere, and the treatment process is staged by stage heating and chlorination; step 3, desublimating the gas generated after chlorination in each stage; step 4, adding the solid after desublimation in each stage to deionized water, adding a sodium carbonate aqueous solution after mixing, collecting the precipitate, washing and drying to obtain a metal salt product. The present invention is based on the characteristics of Joule heat that can heat quickly and accurately control the temperature, combined with the difference in the temperature of the chlorination reaction of different metal oxides and the gasification temperature of the chlorination product, to achieve staged gasification and desublimation treatment, obtain different metal chlorides, and purify accurately and efficiently.

The invention relates to a mixing device for producing a hydroxyl iron series desulfurization catalyst, and belongs to the technical field of hydroxyl iron series desulfurization catalyst production equipment. The device comprises a reaction container, a solution stirring assembly, a precipitation stirring assembly, a crushing sieve assembly, a lifting assembly and an oxygen supply assembly are arranged in the reaction container, the precipitation stirring assembly is used for stirring precipitation and comprises stirring blades, and the crushing sieve assembly comprises a pressing plate and at least two sieve plates; the sieve plate is installed in the reaction container in an up-down elastic sliding mode, the lifting assembly comprises an external spiral auger, the crushing sieve assembly is sleeved with the external spiral auger, the top end of the external spiral auger extends to the position above the sieve plate located at the top, the bottom end of the external spiral auger extends to the bottom of the reaction container, and the oxygen supply assembly comprises an exhaust hole used for exhausting oxygen. And the exhaust holes are positioned below the bottommost sieve plate. The device can refine precipitates, and is beneficial to improving the oxidation reaction rate.

The invention provides coated SnO and FeOx composite oxide powder and a silver-based composite electric contact material and a preparation method thereof, and the preparation method comprises the following steps: providing stannous mono-sulphate, dissolving, stirring to form a SnSO4 solution, and continuously reacting to obtain a solution A; adding an alkaline reaction solution into the solution A to reach a preset pH value to obtain a precursor solution; performing hydrothermal reaction on the precursor solution; washing and drying a hydrothermal reaction product to obtain SnO powder; the preparation method comprises the following steps: adding FeSO4 or FeCl2 into an aqueous solution containing SnO powder, dissolving, adding H2C2O4 to obtain a precipitate, filtering, separating, and drying; and carrying out vacuum heat treatment on the precipitate to obtain the coated SnO-coated FeOx composite oxide powder. The SnO-coated FeOx composite oxide with a controllable and adjustable valence structure can be formed, and the composite oxide is firstly applied to the field of silver-based composite electric contact, so that the Ag / SnO-coated FeOx composite electric contact material has the performance advantages of low temperature rise, long cycle life and the like in the service process.

The invention discloses a method for recovering Mo and Fe from direct coal liquefaction oil residues, and belongs to the technical field of hydrometallurgy. The method comprises the steps of solvent extraction, roasting enrichment, wet leaching, extracting agent extraction, ammonia water reverse extraction and evaporative crystallization, and ammonium molybdate and Fe (OH) 3 are obtained. Wherein in the wet leaching process, a leaching aid and sulfuric acid are jointly used for leaching, so that Ca and Si in the oil residues are left in leaching residues, and Mo, Fe, Al and the like enter a solution. The method comprises the following steps: simultaneously extracting Mo and Fe from a solution by using an extracting agent, precipitating Fe in a Fe (OH) 3 state by using an ammonia water reverse extraction method, leaving Mo in a reverse extraction solution in the form of ammonium molybdate, and further evaporating and crystallizing the reverse extraction solution to obtain the ammonium molybdate. According to the method, two valuable metals Mo and Fe in the direct coal liquefaction oil residue can be effectively recovered, and resource recycling is facilitated.

The present application relates to a sodium-ion battery precursor, a positive electrode material, a preparation method, and a use. A complexing agent solution used for preparing the sodium-ion battery precursor comprises a first complexing agent and a second complexing agent, wherein the first complexing agent comprises any one of or a combination of at least two of oxalic acid, sodium oxalate, or potassium oxalate, and the second complexing agent comprises any one of or a combination of at least two of citric acid, sodium citrate, or potassium citrate. In the present application, by providing the specific complexing agents, the prepared sodium-ion battery precursor has a relatively high specific surface area, thereby facilitating the intercalation of sodium ions when sintering and preparing a positive electrode material, so that the electrochemical performance of the sodium-ion battery positive electrode material can be significantly improved.

The invention discloses a ternary positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The method comprises the following steps: modifying a ternary matrix material in a composite doping manner of rare earth elements and transition metals, and then coating the surface of the material with a layer of amorphous ferric fluoride in a manner of combining atomic layer deposition with fluorination reaction. The ternary positive electrode material provided by the invention has higher rate capability and better cycling stability, and can maintain better chemical performance under high current density, so that the problems of capacity loss and poor electrical performance of the ternary positive electrode material of the lithium battery in a high-voltage long-cycle process are greatly relieved.

The invention relates to a comprehensive utilization major cycle process in cooperative treatment of industrial flue gas pollutants, which comprises the following steps: removing SO2 and NOx in flue gas by adopting an adsorption method, and desorbing SO2 and NOx by adopting a water solution method to generate sulfuric acid and nitric acid; sulfuric acid reacts with sodium chloride to produce hydrochloric acid; sulfuric acid, nitric acid and hydrochloric acid are combined into a composite acid solvent, the solvent dissolves aluminum oxide in the fly ash to be converted into polybasic acid aluminum, the polybasic acid aluminum is subjected to ammonification decomposition into aluminum hydroxide and composite acid ammonium, the composite acid ammonium reacts with calcium carbonate to generate NH3, CO2 and polybasic acid calcium, and the polybasic acid calcium reacts with sodium sulfate to generate nano calcium sulfate; the method comprises the following steps: reacting silicon dioxide with sodium hydroxide to generate sodium silicate, reacting sodium silicate with sodium bicarbonate to generate silicic acid and sodium carbonate, reacting sodium carbonate with calcium hydroxide to generate calcium carbonate and sodium hydroxide, and mixing multi-element metal oxide separated from aluminum and silicon extraction with silicon dioxide and aluminum hydroxide which are separated and carried to prepare a multi-element cation molecular sieve; and comprehensive utilization and large circulation of the flue gas pollutants are realized through the synergistic effect of the pollutants.

A Janus particle, comprising a particle core, the particle core comprising at least a first surface functionalized with a functional group and a second surface functionalized with a metal particle.

The invention belongs to the field of battery positive electrode materials, and particularly relates to a preparation method of a ferrous phosphate precursor, a Fe < 3 + > solution and a phosphate radical source solution with the Fe / P element ratio of 3: (1.8-2.1) are mixed and subjected to a first-stage precipitation reaction in advance, and the initial pH A of the first-stage precipitation reaction is 0.5-2; then supplementing an alkaline substance to carry out a second-stage precipitation reaction under the condition that the pH value is 2.5-5, and then carrying out solid-liquid separation to obtain an iron phosphate-Fe (OH) 3 composite material; and compounding the iron phosphate Fe (OH) 3 composite material with a carbon source, and carrying out reduction roasting treatment to obtain the ferrous phosphate precursor. The invention also comprises a preparation method and application of the material. According to the method, the performance of the prepared material can be improved, and the low-temperature and batch quality stability of the material is particularly facilitated.

The invention discloses a comprehensive utilization method of refining slag, which comprises the following steps: dissolving the refining slag in hydrochloric acid to obtain a refining slag pickle liquor; filtering the refining slag pickle liquor to obtain first filtrate and filter residues, and washing the filter residues to obtain first solid and first washing liquor; combining the first washing liquid and the first filtrate to obtain a second mixed solution; and adding an oxidizing agent into the second mixed solution to obtain a first precipitate. According to the method, the refining slag is subjected to acid leaching with hydrochloric acid, the PH value of the solution is adjusted, silicon dioxide, aluminum hydroxide, ferric hydroxide, calcium chloride or calcium oxide and recycled hydrochloric acid are obtained, the accumulated refining slag is decomposed into various new substances in the process reaction, the method is simple, the substance purity is high, the refining slag is recycled, and large economic value can be created; and meanwhile, mining of various resources is reduced. And a new direction is found for comprehensive utilization of the refining slag.

The invention provides a method for electrochemical synthesis of urea. According to the invention, a metal-doped catalyst with an asymmetric oxygen vacancy structure is designed and prepared, and CO2 and nitrate are catalytically converted into urea by using the catalyst as an electrode material and CO2 and nitrate as raw materials in an H-type electrolytic tank by using an electrochemical means. The Faraday efficiency of the obtained main product urea reaches 63%, and the generation rate of the urea reaches 7.5 g / h <-1 > gcat <-1 >.

Black mass from disused lithium batteries is leached for recovery of various metals in a process that includes precipitation, solvent exchange, ion exchange, and salt splitting to create multiple product streams for recovery of pure value products. Most typically, the process is a closed-loop process and allows for production of metallic cobalt and nickel, EMD, and a high purity lithium hydroxide or carbonate product with minimal generation of waste streams.

The invention discloses a high-entropy double hydroxide / carbon fiber aerogel electromagnetic wave-absorbing material and a preparation method thereof, and the method specifically comprises the following steps: (1) activating green algae to obtain carbon fibers, and freeze-drying the carbon fibers to obtain aerogel carbon fibers; (2) immersing the aerogel carbon fiber subjected to heat treatment into a high-entropy layered double hydroxide precursor solution for hydrothermal reaction, and obtaining a high-entropy double hydroxide / carbon fiber aerogel material after the reaction; wherein the temperature of the hydrothermal reaction is 115-120 DEG C, and the reaction time is not less than 5 hours; and (3) freeze-drying the aerogel material obtained in the step (2) to obtain a target product. The high-entropy double hydroxide / carbon fiber aerogel electromagnetic wave-absorbing material disclosed by the invention can realize low-frequency absorption of 2.46 GHz under 2 to 8 GHz, and can realize broadband absorption of 12.44 GHz under 2 to 18 GHz.

The invention discloses a clean, efficient and low-cost lithium extraction slag utilization method which comprises the following steps: mixing lithium extraction slag with a fluxing agent, and sequentially carrying out roasting treatment, solid-liquid separation treatment, aging treatment and water leaching treatment to obtain a second solid-liquid mixture; carrying out solid-liquid separation treatment on the second solid-liquid mixture to obtain a second filter residue and a second filtrate; performing carbon separation method treatment on the first filtrate to obtain a third solid-liquid mixture; carrying out solid-liquid separation treatment on the third solid-liquid mixture to obtain a third filter residue and a third filtrate; the main component of the second filter residue and the third filter residue is white carbon black; performing heat treatment on the second filtrate and the third filtrate to obtain a fourth solid-liquid mixture; performing solid-liquid separation treatment on the fourth solid-liquid mixture to obtain fourth filter residues and fourth filtrate; the main components of the fourth filter residue are aluminum hydroxide and ferric hydroxide; and separating the fourth filtrate to obtain a sodium sulfate crystal substance and a potassium sulfate crystal substance.

The invention provides an aluminum ash pickling, impurity removing and recycling process. The aluminum ash pickling, impurity removing and recycling process comprises the following steps that S1, aluminum ash is subjected to deamination treatment; s2, diluted hydrochloric acid is added into the deaminated aluminum ash, and impurity elements such as Fe, Ca, Na and F are dissolved; s3, filtering and separating, wherein the obtained solid is a high-alumina-content product subjected to impurity removal; s4, lime and Na2CO3 are added into the pickling wastewater, so that Fe, Ca and F ions in the filtrate react and then are respectively precipitated and removed; s5, filtering and separating precipitated solids, and recycling filter cakes as byproducts of Fe, Ca and F; s6, the filtrate is subjected to evaporation treatment, and concentrated halide salt serves as a by-product. The deaminated aluminum ash product subjected to acid pickling purification is high in additional value, no wastewater is discharged, the deaminated aluminum ash product is more environmentally friendly, the removal rate of by-products obtained in all the steps is high, and particularly the removal rate of fluorine ions is high, so that the fluorine ions remaining in the solution during final evaporation are few, and corrosion to evaporation equipment is effectively avoided.

The method for preparing nickel sulfate according to an exemplary embodiment may prepare a nickel-containing raw material. Nickel may be selectively leached from a nickel-containing feedstock using an oxidant to produce a first leachate. Residual metals may be separated from the first leachate to produce a second leachate. Nickel sulfate may then be obtained from the second leachate. Therefore, a separate nickel extraction step can be omitted, thereby reducing unnecessary by-products.

The invention discloses a spinel oxygen carrier with the capability of deeply releasing lattice oxygen as well as a preparation method and application thereof, and belongs to the related technical field of hydrogen energy preparation. Elements such as Cu, Mn, Ni, Ca, Sr and the like are doped into a metal iron-based oxygen carrier AFe2O4 with a spinel type structure according to an equal molar ratio, a dilution effect is shown on A-site atoms of the spinel type oxygen carrier AFe2O4 by virtue of multiple metal elements, and a multi-metal effect for promoting lattice oxygen release is combined. In addition, the spinel type oxygen carrier (AFe2O4) has excellent adsorption capacity and cycling stability, and the novel oxygen carrier is applied to chemical looping hydrogen production (CLR) to realize recycling of waste plastics and efficient preparation of high-purity hydrogen. Therefore, the problems of insufficient activity, serious surface carbon deposition, poor cycling stability and the like of a pure Fe2O3 oxygen carrier in chemical looping hydrogen production (CLR) are solved.

The invention discloses a recyclable waste lithium iron phosphate positive electrode material eutectic solvent and a recovery method, and relates to the technical field of lithium iron phosphate extraction. The catalyst is prepared by mixing a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is choline chloride, the hydrogen bond donor is a mixture of citric acid and ascorbic acid, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is (0.5-2): 1, and the molar ratio of citric acid to ascorbic acid is (0.5-2): 1; by arranging the eutectic solvent mixed with the hydrogen bond donor, the purposes that lithium iron phosphate can be efficiently leached at low temperature, meanwhile, the product purity is improved, cyclic utilization can be achieved, and no waste water or waste gas is generated in the whole process are achieved.

Described are methods for producing industrial gases (e.g., hydrogen, ammonia, and / or methane) using ferrous iron-containing materials (e.g., olivine) while concurrently sequestering carbon dioxide. The process may involve mixing a ferrous iron-containing material with water and, in some examples, a reaction accelerant. The mixture may be heated to 100-300°C to initiate the oxidation of ferrous cations (Fe2+) to ferric cations (Fe3+) while reducing hydrogen (from water) and / or methane (from water and carbon dioxide, when carbon dioxide is introduced into the ferrous iron-containing mixture). In some examples, carbon dioxide may be added later (after recovering hydrogen) to form carbonates. Specifically, carbon dioxide may be injected at a high pressure (e.g., about 200 bar) post-oxidation to facilitate mineralization, using the exothermic reaction to maintain a favorable temperature. In some examples, metal complexing / chelating reagents are added to bind trace metals such as nickel, copper, cobalt, and platinum group metals for recovery.