A method for coupling tungsten extraction by chemical leaching of tungsten ore after mixed tungsten ore reinforced roasting

Abstract

The present application relates to the technical field of metallurgical engineering, and discloses a method for coupling tungsten extraction by mixed tungsten ore strengthening roasting and chemical leaching, which comprises the following steps: placing mixed tungsten ore powder in a fluidized preheating boiling reaction furnace, and spraying the mixed tungsten ore powder into low-melting-point alkali metal eutectic salt containing microcapsule pore-forming agents. The microcapsule pore-forming agents are gasified in situ in the roasting sand to build a micron-level directional through-hole network, and the solid-phase diffusion resistance is eliminated to realize synchronous deconstruction of the crystal lattice. The roasting sand is placed in a pressure leaching kettle, an alternating pressure field is constructed to force the water phase leaching solution containing polydentate ligands to penetrate into the deep part of the hole network, and high-frequency ultrasonic pulses are triggered at the low-pressure phase to induce cavitation microjet to expose fresh mineral phases. The polydentate ligands undergo spatial configuration inversion and in-situ complexation with metal impurity cations to block the thermodynamic path of secondary precipitation. The mixed ore slurry is subjected to solid-liquid separation and ion exchange to extract target products. The present application effectively eliminates the roasting mass transfer bottleneck and prevents leaching secondary precipitation, and improves the tungsten extraction rate.

Description

Technical Field

[0001] This invention relates to the field of metallurgical engineering technology, specifically to a method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching coupled with chemical extraction. Background Technology

[0002] In tungsten metallurgy, for the widely existing mixed mineral systems of wolframite and scheelite, a combined extraction technique combining pyrometallurgical roasting and hydrochemical leaching is typically employed. This technique utilizes chemical reactions to break down tungsten from its complex mineral lattice and transform it into tungstates soluble in an aqueous system. It is the core metallurgical pathway for the industrial extraction of refractory tungsten resources.

[0003] In existing technologies, the conventional roasting process for processing mixed tungsten ore mainly employs the soda ash sintering method, which involves mechanically mixing mixed tungsten ore powder with solid soda ash according to a specified ratio. The resulting solid material is placed in a high-temperature thermal device such as a rotary kiln or reverberatory furnace for solid-phase roasting at a high temperature of 800°C to 900°C. During the roasting process, a chemical reaction occurs between the surface of the tungsten ore solid particles and the solid soda ash to generate solid sodium tungstate. After the roasting reaction has reached the set time, the resulting roasted sand is removed from the furnace, cooled, and transferred to a stirred reactor where an aqueous medium is injected for atmospheric pressure leaching, thereby transferring sodium tungstate to the liquid phase.

[0004] Existing solid soda ash roasting processes suffer from significant solid-phase diffusion resistance defects at the reaction kinetics level. Since the interfacial reaction between solid soda ash and tungsten ore particles in the roasting system primarily relies on physical point contact, as chemical decomposition progresses, the resulting solid sodium tungstate and associated byproducts rapidly accumulate and solidify on the surface of the unreacted tungsten ore core, forming an extremely dense solid product coating layer. This dense coating structure completely blocks further penetration of external reactants into the ore particle core, causing the later stages of the reaction to be entirely constrained by the unreacted core contraction model, resulting in a significant decrease in mass transfer rate. Even with extended high-temperature roasting times or excessive amounts of reactant in industrial operations, it is still impossible to overcome the physical isolation of this dense coating layer, ultimately preventing the complete decomposition of the deep lattice within the mixed tungsten ore and directly limiting the absolute conversion rate of the overall extraction process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for enhanced roasting and chemical leaching coupled with tungsten extraction from mixed tungsten ore, thus solving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for enhanced roasting and chemical leaching coupled with tungsten extraction from mixed tungsten ore, comprising the following steps: introducing mixed tungsten ore powder into a fluidized bed reactor, blowing hot carrier gas into the fluidized bed reactor to maintain the mixed tungsten ore powder in a fluidized suspension state, and preheating the mixed tungsten ore powder to a preset roasting temperature zone; heating a low-melting-point alkali metal eutectic salt system containing soda ash and microcapsule pore-forming agent to a molten state, and atomizing the molten low-melting-point alkali metal eutectic salt system into the fluidized bed reactor to form eutectic salt aerosol droplets; the eutectic salt aerosol droplets spreading on the surface of the mixed tungsten ore powder to form a dynamic reaction liquid film, the microcapsule pore-forming agent vaporizing in situ within the dynamic reaction liquid film, and constructing a micron-scale directional interconnected pore network within the roasted sand generated by the synchronous deconstruction reaction of the mixed tungsten ore powder; transferring the roasted sand to a pressure leaching vessel, and injecting an aqueous leaching solution and a multidentate ligand into the pressure leaching vessel. A periodic alternating pressure field is constructed within the pressure leaching reactor, forcing the aqueous leachate to penetrate into a micron-sized directional interconnected pore network. When the alternating pressure field decreases to a low-pressure threshold range, high-frequency ultrasonic pulses are triggered to induce acoustic cavitation. Multidentate ligands penetrate deep into the micron-sized directional interconnected pore network and undergo complexation reactions with metal impurity cations to form large, stable complexes. The pressure inside the pressure leaching reactor is then released, and the mixed slurry is transported to a solid-liquid separation unit for solid-liquid separation to obtain tungsten-rich leachate. The tungsten-rich leachate is then introduced into an ion exchange column for further separation and purification.

[0007] This invention achieves innovation in process extraction pathways by constructing a synergistic mechanism between multiphase physical structures and hydrodynamic energy fields. The specific principles of the invention are explained below: During the fluidized bed thermodynamic reconstruction and molten salt aerosol roasting stages, the atomized eutectic salt aerosol droplets possess low liquid-gas surface tension. The balance between solid-gas surface free energy, solid-liquid interfacial tension, and the interfacial tension between liquid-gas surface tension ensures a spreading coefficient greater than zero. This spreading coefficient drives the eutectic salt aerosol droplets to spontaneously spread across the surface of the mixed tungsten ore powder, establishing a liquid-solid full-contact mass transfer interface to replace the conventional point-contact mode of solid-state roasting. The inorganic ammonium salt compound in the microcapsule pore-forming agent core undergoes thermal decomposition after the outer shell melts and ruptures, releasing gaseous substances and evolving into bubble nuclei. The absolute pressure inside the gaseous substances overcomes the liquid-gas surface tension constraint generated by the dynamic reaction liquid film and the external hydrostatic pressure resistance, generating a kinetic driving pressure difference that performs work outward. The directional escape trajectory of the gaseous substances opens physical exhaust channels within the solidified roasted sand, constructing a micron-scale directional interconnected pore network radiating from the particle core to the outer surface, eliminating the solid-phase diffusion resistance effect caused by product coating.

[0008] In the phase-controlled ultrasonic and alternating pressure coupled leaching stage, the sinusoidal wave-like alternating pressure field constructed inside the pressure leaching vessel forms a physical structural connection with the micron-scale directional through-hole network. The high-pressure threshold phase of the alternating pressure field provides hydrostatic pressure to force the aqueous leachate to overcome capillary resistance and penetrate deep into the pores, compressing residual microbubbles. The low-pressure threshold phase causes the compressed microbubbles to expand and squeeze the leaching medium out of the pores, establishing a forced convection exchange mechanism. The system synchronously triggers high-frequency ultrasonic pulses when the transient pressure data decreases and enters the low-pressure threshold range. The local hydrostatic pressure of the aqueous leachate approaches the saturated vapor pressure, reducing the energy threshold required for cavitation phase change. The transient acoustic field pressure applied by the high-frequency ultrasonic pulses amplifies the pressure difference driving force, promoting rapid nucleation and generating a large number of cavitation microbubbles inside the fluid. The cavitation microbubbles collapse instantaneously under the pressure difference recovery, generating high-speed microjets pointing towards the inner wall of the solid phase, stripping the solid reaction residues attached to the inner wall of the pores and exposing fresh tungsten-bearing ore phase interfaces to eliminate local concentration polarization.

[0009] Regarding the microscopic mass transfer enhancement and the anti-precipitation mechanism of multidentate coordination, high-frequency ultrasonic pulses induce a local transient high-temperature and high-pressure microenvironment, transferring hydrodynamic kinetic energy to cause the multidentate ligands to overcome their internal rotational barriers and undergo spatial configuration reversal. The multidentate ligands undergoing spatial configuration reversal dissociate into effectively complexed anions, which then undergo irreversible in-situ complexation reactions with metal impurity cations dissociated from the fresh tungsten-bearing ore phase interface. The macromolecular stable complexes generated by the in-situ complexation reaction significantly reduce the absolute concentration of free metal impurity cations within the aqueous leachate. The absolute concentration of free metal impurity cations is suppressed below the solubility product constant critical value required for the formation of secondary tungstate precipitation. The absence of the solubility product constant condition completely blocks the thermodynamic pathway for the combination of metal impurity cations and free tungstate ions, ensuring that the target product, sodium tungstate, is transferred to the macroscopic aqueous phase via forced convection diffusion.

[0010] This invention provides a method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching coupled with other methods. It offers the following advantages: 1. This invention alters the solid-phase interface contact mode of traditional static roasting of soda ash by constructing a synergistic phase transition mechanism of in-situ vaporization of molten salt aerosol liquid film and microcapsule pore-forming agent. Aerosol droplets spread on the surface of tungsten ore powder to form a liquid-phase mass transfer environment. The internal pore-forming components decompose upon heating, generating an outward-escaped gas phase pressure difference, thus creating a directional, interconnected pore network within the solidified roasted sand. This directional, interconnected pore network eliminates the diffusion resistance caused by the solid product coating layer, achieving simultaneous deconstruction of the mixed tungsten ore lattice.

[0011] 2. This invention solves the problem of pore fluid stagnation in steady-state leaching by introducing a hydrodynamic linkage between an alternating pressure field and phase-locked ultrasonic pulses. High and low pressure circulation forces the aqueous leachate to penetrate and extrude into the directional interconnected pore network, establishing forced convection. The control system utilizes the low-pressure threshold range to synchronously trigger acoustic cavitation, generating high-speed microjets. These microjets impact and peel off solid reaction residues from the inner walls of the pores, exposing fresh tungsten-bearing ore phase interfaces and opening fluid mass transfer channels for the diffusion of the target product to the surrounding bulk.

[0012] 3. This invention utilizes the thermodynamic coupling of acoustic field dynamics and the in-situ complexation reaction of multidentate ligands to block the reverse reaction pathway of impurity metal binding and secondary precipitation during the leaching stage. The transient microenvironment induced by high-frequency ultrasound causes the multidentate ligands to overcome their internal rotational barriers and undergo spatial configuration inversion, rapidly capturing dissociated cations and generating macromolecular stable complexes. These macromolecular stable complexes suppress the concentration of free impurity ions below the critical value of the solubility product constant, ensuring the unidirectional liquid-phase transfer of tungstate ions. Attached Figure Description

[0013] Figure 1 Flowchart of a method for enhanced roasting and chemical leaching coupled with tungsten extraction from mixed tungsten ore; Figure 2 This is a flowchart of step S300 of the present invention. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Example: Please see the appendix Figure 1-2 This invention provides a method for enhanced roasting and chemical leaching coupled with tungsten extraction from mixed tungsten ore, comprising pre-constructing a multiphase synergistic reaction system. The multiphase synergistic reaction system includes a raw ore crushing and grading unit, a fluidized bed roasting unit, a pressure leaching unit, and a solid-liquid separation unit connected in sequence. The fluidized bed roasting unit includes a boiling reactor with a gas distribution plate at the bottom, and a supersonic dual-fluid nozzle array is arranged on the side wall of the boiling reactor. The pressure leaching unit includes a pressure leaching vessel, with an ultrasonic emission array arranged on the outer wall of the pressure leaching vessel, and a programmable booster pump and a servo pressure relief valve connected to the fluid circuit of the pressure leaching vessel. Regarding the configuration of the jaw crusher and vibrating screen in the raw ore crushing and grading unit, those skilled in the art can conventionally select them based on the original particle size of the symbiotic raw ore. The specific structural selection of the raw ore crushing and grading unit is well-known in the art and will not be elaborated further in this specification.

[0016] The process for processing mixed tungsten ore, based on a multiphase synergistic reaction system, includes the following steps.

[0017] S100, Mixed Tungsten Ore Crushing and Fluidized Preheating. The symbiotic raw ore containing wolframite and scheelite is fed into the raw ore crushing and classification unit, where it is ground to the target particle size to obtain mixed tungsten ore powder. The mixed tungsten ore powder is then introduced into a fluidized bed reactor, where hot carrier gas is blown in from bottom to top through a gas distribution plate. The flow rate of the hot carrier gas is controlled to overcome the gravity of the mixed tungsten ore powder, keeping the powder bed in a fluidized suspension state. The hot carrier gas exchanges heat with the mixed tungsten ore powder, preheating it to a preset roasting temperature zone.

[0018] S200, molten salt aerosol-enhanced roasting. A low-melting-point alkali metal eutectic salt system (such as a mixture of sodium and potassium salts) containing soda ash and high-temperature phase change pore-forming components (such as inorganic ammonium salts with specific decomposition temperatures) is prepared and heated to a molten state. The molten low-melting-point alkali metal eutectic salt system is atomized and sprayed into a fluidized bed reactor through a supersonic dual-fluid nozzle array, forming micron-sized eutectic salt aerosol droplets. These droplets collide with fluidized tungsten ore powder and spontaneously spread on the powder surface to form a reaction film. Wolframite and scheelite undergo simultaneous deconstruction reactions within the reaction film to generate sodium tungstate. Simultaneously, the high-temperature phase change pore-forming components vaporize in situ within the reaction film. The channels through which the vaporized components escape are retained after product solidification, constructing a micron-sized directional interconnected pore network radiating outwards from the core within the generated roasted sand particles. Subsequently, calcined sand containing a micron-sized directional through-hole network is continuously discharged from the fluidized bed reactor.

[0019] S300, a phase-controlled ultrasonic alternating pressure coordination leaching process. Calcined sand is transferred to a pressure leaching vessel, and an aqueous leachate and a multidentate ligand (such as disodium ethylenediaminetetraacetate) are injected into the vessel. The control system alternately controls a programmable booster pump and a servo-controlled pressure relief valve, creating a high-frequency alternating pressure field within the vessel that circulates between a set high-pressure threshold and a low-pressure threshold. At the high-pressure threshold, the aqueous leachate is forced into a micron-sized directional through-pore network. When the pressure in the vessel drops to the low-pressure threshold range, the control system synchronously triggers a short-duration high-energy acoustic pulse emitted by an ultrasonic transmitting array. This short-duration high-energy acoustic pulse induces a strong acoustic cavitation effect in the low-pressure aqueous leachate. The microjets generated by the collapse of the acoustic cavitation effect destroy the solid-phase barrier layer on the inner wall of the pores. With the forced convection of the fluid, the multidentate ligand penetrates deep into the micron-scale directional through-pore network and undergoes a complexation reaction with the dissociated metal impurity cations to form stable complexes, thereby blocking the binding pathway of the metal impurity cations and free tungstate ions for secondary precipitation.

[0020] S400, solid-liquid separation and subsequent purification for tungsten extraction. After reaching the set alternating leaching cycle, the pressure relief valve is opened to release the internal pressure of the pressure leaching vessel. The discharge pump transports the reacted slurry from the pressure leaching vessel to the solid-liquid separation unit, where tungsten-rich filtrate is obtained after physical separation and tailings removal. The specific pressure filtration operation performed by the solid-liquid separation unit, and the subsequent purification and deimpurification of the tungsten-rich filtrate to prepare ammonium paratungstate via ion exchange or extraction, can be achieved by those skilled in the art using conventional metallurgical separation and purification processes. These purification processes are well-known in the field and will not be described further in this specification.

[0021] The specific technical features of the mixed tungsten ore crushing and fluidized preheating operation involved in the aforementioned step S100 are broken down as follows.

[0022] S101, Closed-Circuit Grinding and Particle Size Classification of Mixed Tungsten Ore. The raw ore crushing and classification unit receives symbiotic raw ore containing wolframite and scheelite. The symbiotic raw ore undergoes primary crushing treatment by a jaw crusher. A vibrating screen and a ball mill form a closed-circuit grinding and classification loop. The symbiotic raw ore after primary crushing is input into the closed-circuit grinding and classification loop for cyclic crushing. The particle size classification operation controls the average equivalent diameter of the mixed tungsten ore powder within a preset range (e.g., 60 mesh to 200 mesh). Controlling the average equivalent diameter ensures that the solid mineral particles have matching hydrodynamic drag characteristics in the subsequent gas-solid two-phase flow. For the specific selection of the equipment speed parameters of the jaw crusher and ball mill, as well as the mesh size and model of the vibrating screen, those skilled in the art can make conventional configurations based on the physical hardness of the symbiotic raw ore. The specific selection and configuration of grinding equipment parameters are well-known technologies in the field and will not be elaborated in the text of this specification.

[0023] S102, Gas distribution and fluidized bed establishment in the fluidized bed reactor. A feed screw conveyor quantitatively delivers the mixed tungsten ore powder into the fluidized bed reactor. A blower pumps hot carrier gas (such as heated air or inert nitrogen) upwards through a gas distribution plate at the bottom of the fluidized bed reactor. As a specific implementation of this feature, a porous media layer is installed inside the gas distribution plate. This porous media layer is specifically manifested as a sintered metal porous plate structure or a closely spaced vent cap-type distribution plate structure. The porous media layer creates throttling resistance on the airflow input by the blower to homogenize the hot carrier gas flow field. The apparent velocity of the rising hot carrier gas must be greater than the minimum fluidization velocity of the mixed tungsten ore powder. Minimum fluidization velocity... The fluidization rate is determined by the combined physical properties of the mixed tungsten ore powder and the properties of the hot carrier gas. Based on a simplified gas-solid-fluid resistance balance model, the physical and mathematical expression for the minimum fluidization rate is as follows: In the formula, The true density of the mixed tungsten ore powder is the solid true density. The density of the heat carrier gas. Represents gravitational acceleration. Represents the average equivalent diameter of the mixed tungsten ore powder. This represents the dynamic viscosity of the heat transfer gas. The control system adjusts the frequency conversion parameters of the blower to maintain the apparent gas velocity inside the fluidized bed reactor within a specific multiple of the minimum fluidization velocity. The apparent gas velocity forces the mixed tungsten ore powder bed to overcome the gravity of the solid particles and the friction between them. The mixed tungsten ore powder bed expands upward from its static accumulation at the bottom, forming a fluidized suspension state of gas-solid two-phase mixing.

[0024] S103 features high-frequency heat exchange and uniform-temperature targeted preheating. The mixed tungsten ore powder in a fluidized suspension state exhibits disordered particle movement and mixing characteristics. Heat carried by the carrier gas undergoes high-frequency heat transfer between the gas and solid phases within the fluidized bed. This disordered particle movement eliminates localized temperature gradients within the boiling reactor bed. The control system adjusts the inlet temperature of the carrier gas, ensuring that the mixed tungsten ore powder in its fluidized suspension state is heated as a whole and maintained at a preset roasting temperature range of 550℃ to 650℃. This uniform-temperature preheating operation provides thermodynamically stable initial conditions for the subsequent eutectic salt liquid-phase reaction.

[0025] Following the uniform temperature targeted preheating operation in step S103, the subsequent process enters the molten salt aerosol generation and liquid-solid phase change coating transfer stage. The specific implementation details of the molten salt aerosol generation and liquid-solid phase change coating mechanism are broken down and discussed.

[0026] S201, Preparation and Melting State Control of the Eutectic Salt System. The mixing tank receives the calcination reaction raw materials. These raw materials include solid soda ash as the main reactant and fluxing agents used to lower the melting point of the reaction system. Specifically, the low-melting-point alkali metal eutectic salt system employs a sodium carbonate-potassium nitrate-sodium chloride ternary eutectic. The heating element within the mixing tank heats the sodium carbonate-potassium nitrate-sodium chloride ternary eutectic. The sodium carbonate-potassium nitrate-sodium chloride ternary eutectic absorbs heat and crosses the solid-liquid eutectic point, transforming into a molten liquid phase. This liquid phase possesses low-viscosity fluid physical properties suitable for nozzle atomization. For the selection and configuration of the heating element and stirring device inside the mixing tank, those skilled in the art can make conventional selections based on the melting point of the ternary eutectic. The selection and configuration of the heating element and stirring device are well-known techniques in the field and will not be elaborated further in this specification.

[0027] S202, Supersonic Two-Fluid Atomization and Aerosol Generation. A high-temperature resistant supply pump draws a molten low-melting-point alkali metal eutectic salt system. The high-temperature resistant supply pump pressurizes and delivers the low-melting-point alkali metal eutectic salt system to a supersonic two-fluid nozzle array installed on the side wall of the fluidized bed reactor. The supersonic two-fluid nozzle array simultaneously receives high-pressure compressed gas (such as compressed air or compressed nitrogen). The high-pressure compressed gas, as the atomization power source, undergoes high-speed shearing collisions with the low-melting-point alkali metal eutectic salt system inside the supersonic two-fluid nozzle array. The low-melting-point alkali metal eutectic salt system is torn apart and dispersed into micron-sized droplets by the shearing force of the high-pressure compressed gas. The micron-sized droplets are suspended and diffused within the fluidized bed reactor, forming a eutectic salt aerosol. The eutectic salt aerosol moves with the airflow field inside the fluidized bed reactor.

[0028] S203, thermodynamically driven dynamic reaction film spreading. Eutectic salt aerosol droplets in a suspended, diffused state collide with fluidized, preheated mixed tungsten ore powder. Upon contact with the mixed tungsten ore powder surface, the eutectic salt aerosol droplets trigger phase change wetting behavior. The spontaneous spreading force of this phase change wetting behavior is determined by the spreading coefficient in fluid thermodynamics. Based on the interfacial tension balance, the mathematical expression for the spreading coefficient is defined as: In the formula, This represents the spreading coefficient of eutectic salt aerosol droplets on the surface of mixed tungsten ore powder. The solid-gas surface free energy represents the solid-gas surface free energy of the mixed tungsten ore powder. This represents the solid-liquid interfacial tension between the mixed tungsten ore powder and the eutectic salt aerosol droplets. The liquid-gas surface tension represents the liquid-gas surface tension of eutectic salt aerosol droplets.

[0029] Because eutectic salt aerosol droplets at high temperatures possess low liquid-gas surface tension, the physical relationship defined by substituting the surface tension parameter into a mathematical expression determines the spreading coefficient. A spread factor greater than zero forces the eutectic salt aerosol droplets to rapidly spread and expand on the surface of the mixed tungsten ore powder. These spread-out eutectic salt aerosol droplets then connect on the surface of the mixed tungsten ore powder to form a dynamic reaction liquid film with a thickness of nanometers or micrometers. This dynamic reaction liquid film replaces the point contact mode between solid soda ash and solid ore in the traditional solid soda ash roasting process. The dynamic reaction liquid film encapsulates the mixed tungsten ore powder particles in a liquid-phase microenvironment, establishing the liquid-solid full-contact mass transfer interface required for subsequent synchronous lattice deconstruction chemical reactions.

[0030] Following the dynamic reaction liquid film's spreading and stabilization, the high-temperature phase change pore-forming components distributed within the film initiate in-situ vaporization and phase change. The implementation details of the linkage between the in-situ vaporization of the high-temperature phase change pore-forming components and the construction of a micron-scale directional interconnected pore network are discussed and broken down.

[0031] S204, High-Temperature Phase Change Pore-Forming Component: Endothermic and Phase Change Triggering. To prevent premature vaporization of the high-temperature phase change pore-forming component during the initial melting stage in the mixing tank, a microcapsule pore-forming agent with a core-shell structure is specifically used. The core of the microcapsule pore-forming agent is an inorganic ammonium salt compound (such as ammonium sulfate or ammonium chloride), and the outer shell is a high-temperature resistant inert wall material with a melting temperature matching the calcination temperature range of 550℃ to 650℃. The microcapsule pore-forming agent, situated in the dynamic reaction liquid film microenvironment, continuously absorbs heat transferred from the fluidized bed of the boiling reactor. The outer shell of the microcapsule pore-forming agent crosses the melting point of the wall material and undergoes melting and rupture, causing the inorganic ammonium salt compound in the core to be directly exposed to the high-temperature environment and instantly reach the critical point of chemical decomposition. The inorganic ammonium salt compound undergoes a violent thermal decomposition reaction, releasing a large amount of gaseous substances. The free gaseous substances aggregate and nucleate at the liquid-solid interface, evolving into micron-scale bubble nuclei.

[0032] S205, Gas-phase expansion work and directional opening of exhaust channels. Under constant high-temperature calcination conditions, the micron-scale bubble nuclei continuously expand, outputting gas-phase expansion pressure to the surrounding liquid boundary layer. This gas-phase expansion pressure forces the gaseous material to overcome the surface tension constraints generated by the dynamically reacting liquid film and the hydrostatic resistance of the surrounding fluid. The kinetic driving pressure difference for the bubble nuclei to break through the interfacial physical constraints and continuously grow is defined by an interphase mechanical equilibrium model. The physical and mathematical expression of this kinetic driving pressure difference is as follows: In the formula, The pressure difference representing the dynamic driving force for the work done by the outward escape of gaseous substances. Represents the absolute pressure of the gaseous substance inside the bubble nucleus. External hydrostatic pressure representing the dynamic reaction liquid film microenvironment. The liquid-gas surface tension represents the dynamic reaction liquid film. The instantaneous radius of curvature represents the bubble nucleus.

[0033] The kinetic pressure difference forces gaseous substances to escape from the core region of the mixed tungsten ore particles to the outer liquid surface. The directional escape trajectory of the gaseous substances creates physical exhaust channels within the dynamic reaction liquid film, forcibly penetrating the tungstate reaction product layer that is simultaneously solidifying on the surface of the mixed tungsten ore particles.

[0034] S206, a micron-scale directional through-pore network structure is finalized. With the large-scale consumption of liquid reactants and the continuous generation of solid tungstate reaction products, the dynamic reaction liquid film gradually loses its fluidity and completely transforms into a solid calcined sand product shell. This solid calcined sand product shell completely preserves the physical exhaust channels opened during the gas phase escape stage. These solidified physical exhaust channels interweave and combine within the calcined sand particles, constructing a micron-scale directional through-pore network radiating from the particle core to the outer surface. This micron-scale directional through-pore network penetrates the dense calcined sand product shell, eliminating the solid-phase diffusion resistance effect caused by the unreacted core being encapsulated by dense products in conventional solid-state calcination processes. The through-pore network structure provides microscopic fluid channels for the aqueous leachate to penetrate deep into the calcined sand particle core in the subsequent alternating pressure coordination leaching process, establishing a rigid physical structural linkage between the preceding and following process steps. For the specific determination of the porosity parameter of calcined sand particles, those skilled in the art can use a mercury porosimeter or a specific surface area analyzer for routine measurement. The routine measurement operation of porosity is a well-known technique in the field and will not be described in detail in the specification text.

[0035] The dynamically spreading reaction liquid film provides a continuous and fully encapsulated liquid-phase mass transfer channel for the mixed tungsten ore powder. Accompanying the melting of the microcapsule pore-forming agent shell and the vaporization of internal components, the wolframite and scheelite lattices within the mixed tungsten ore powder simultaneously initiate chemical deconstruction in the liquid-phase microenvironment. The specific implementation details of the kinetics of the synchronous lattice deconstruction chemical reaction are discussed in detail.

[0036] S207, Oxidation-Destruction Reaction at the Wolframite Phase Interface. The wolframite component in the mixed tungsten powder mainly consists of ferrous tungstate and manganese tungstate. Ferrous tungstate and manganese tungstate, distributed in the dynamic reaction liquid film microenvironment, come into physical contact with molten sodium carbonate. When heated air is blown into the bottom of the boiling reactor, the oxygen contained in the hot carrier gas penetrates the dynamic reaction liquid film and enters the liquid-solid reaction interface. Ferrous tungstate and manganese tungstate undergo gas-liquid-solid three-phase oxidation-destruction reactions with sodium carbonate and oxygen, respectively. The reaction process corresponds to the following chemical reaction equation: In the formula, Represents ferrous tungstate molecules, Represents sodium carbonate molecules. Represents oxygen molecules. Represents sodium tungstate molecules, Represents iron oxide molecules, Represents carbon dioxide molecules. Represents manganese tungstate molecules, This represents manganese dioxide molecules. Through a gas-liquid-solid three-phase oxidation destructive reaction, the wolframite lattice is completely destroyed, releasing the target product, sodium tungstate.

[0037] S208, the displacement-deconstruction reaction at the scheelite phase interface. The scheelite component in the mixed tungsten powder is mainly composed of calcium tungstate. Calcium tungstate undergoes a reversible displacement reaction with sodium carbonate in the dynamic reaction liquid film microenvironment. The high-temperature liquid-phase mass transfer environment provided by the dynamic reaction liquid film reduces the activation energy required for the displacement reaction. The relevant chemical reaction equations are as follows: In the formula, Represents calcium tungstate molecules, This represents calcium carbonate molecules. Eutectic salt aerosol droplets continuously injected into the sidewall of the boiling reactor replenish the consumed sodium carbonate. This continuous replenishment of sodium carbonate maintains a high concentration of sodium carbonate within the dynamic reaction film. This high concentration forces the chemical equilibrium of the displacement reaction to continuously shift towards the formation of sodium tungstate, ensuring that the scheelite component reaches the set conversion rate during the roasting stage.

[0038] S209, Elimination of reaction product free and solid-phase diffusion resistance. In conventional mineral static roasting processes, solid soda ash reacts with tungsten ore particles through point contact. The reaction products form a dense solid coating layer on the surface of the unreacted ore particle core, inducing diffusion resistance. The core shrinkage effect occurring during conventional mineral static roasting can be understood by those skilled in the art through macroscopic kinetic deduction using the classical unreacted core shrinkage model. The principle of the classical unreacted core shrinkage model is well-known in the field and will not be elaborated further in this specification.

[0039] Utilizing a multiphase synergistic reaction system, sodium tungstate generated by the oxidation-destruction reaction and the displacement-destruction reaction directly dissolves and becomes free within the dynamic reaction liquid film. The dissolved sodium tungstate detaches from the original solid-phase reaction interface and diffuses into the liquid phase, completely blocking the formation path of the dense solid coating layer. The difference in activation energy between the wolframite and scheelite components in the dynamic reaction liquid film microenvironment is smoothed out by liquid convection mass transfer, enabling the two mineral phases to achieve a synchronous destructive state within the 550℃ to 650℃ roasting temperature range. The release mechanism of the reaction products, combined with the micron-scale directional interconnected pore network constructed by the gasification of the pore-forming components, completely reconstructs the particle morphology of the mixed tungsten ore powder and continuously outputs roasted sand material with a porous structure to the pressure leaching unit.

[0040] The system receives roasted sand material with a porous structure from the fluidized bed roasting unit and enters the phase-controlled ultrasonic and alternating pressure coupled leaching stage of the multiphase synergistic reaction system. The specific implementation details of the pressure leaching system configuration and alternating pressure field settings are discussed in detail.

[0041] S301, Material Loading and Fluid Configuration for the Pressure Leaching System. The core equipment of the pressure leaching unit is the pressure leaching vessel. The pressure leaching vessel receives roasted sand material discharged from the fluidized bed roasting unit. A dosing pump injects an aqueous leachate (such as deionized water) and a multidentate ligand into the pressure leaching vessel. The injected multidentate ligand is disodium ethylenediaminetetraacetate or citrate, used to provide a specific chemical complexation microenvironment. The aqueous leachate and the multidentate ligand mix inside the pressure leaching vessel to form a leaching medium with specific complexing capabilities. The pressure leaching vessel is sealed by closing the feed end. After the feed end of the pressure leaching vessel is sealed, the control system activates the programmable booster pump and servo-controlled pressure relief valve connected to the fluid circuit of the pressure leaching vessel. For the configuration and operation of the mechanical seal structure and internal anchored agitator of the pressure leaching vessel, those skilled in the art can select the appropriate type by combining the conventional pressure-resistant and corrosion-resistant standards of metallurgical leaching processes. The selection and configuration of the basic hardware of the pressure leaching vessel are well-known technologies in this field and will not be described in detail in the specification text.

[0042] S302, Construction of the physical model of the alternating pressure field. The control system sends high-frequency alternating execution commands to the programmable booster pump and the servo-controlled pressure relief valve. The programmable booster pump and the servo-controlled pressure relief valve operate in tandem, constructing a periodic alternating pressure field inside the pressure leaching vessel. The physical law governing the change of the alternating pressure field over time is set as a sinusoidal fluctuation. The functional relationship expression of the alternating pressure field is defined as follows: In the formula, This represents the transient pressure that changes in real time inside the pressure leaching vessel. This represents the cyclic base equalization pressure set by the alternating pressure field. This represents the amplitude of pressure alternation. Represents alternating frequency. This represents the time required for the leaching process.

[0043] The control system sets the limit output parameters for the programmable booster pump to maintain the high pressure threshold achievable inside the pressure leaching reactor at the 1.5 MPa level. Simultaneously, the control system sets the opening and venting parameters for the servo-controlled pressure relief valve to maintain the low pressure threshold achievable inside the pressure leaching reactor at the 0.1 MPa level. The alternating frequency of the alternating pressure field... The control system sets its parameter range to match the low-frequency range (e.g., 0.5Hz to 5Hz) of the mechanical pump valve action response.

[0044] S303, Micromechanical Pumping Effect and Directional Convection Enhancement. A high-frequency alternating pressure field directly acts on the micron-scale directional interconnected pore network left by the previous phase transformation within the calcined sand material. When the alternating pressure field is at the 1.5 MPa high-pressure threshold phase, the static pressure of the external high-pressure fluid forces the aqueous leachate containing multidentate ligands to overcome the capillary resistance inside the pores. The aqueous leachate is forcibly compressed and penetrates deep into the micron-scale directional interconnected pore network. This penetration action simultaneously compresses the microbubbles remaining inside the pores. When the pressure inside the pressure leaching vessel drops to the 0.1 MPa low-pressure threshold phase, the compressed microbubbles inside the pores lose their external high-pressure constraint and undergo instantaneous volume expansion. The repulsive force generated by this volume expansion forces the leaching medium containing dissolved sodium tungstate products out of the pores. The high-pressure penetration and low-pressure extrusion actions continuously cycle with the alternating frequency, establishing a forced convection exchange mechanism inside and outside the calcined sand material particles. The forced convection exchange mechanism breaks through the mass transfer limitations of conventional leaching processes that rely on static concentration difference diffusion, eliminates fluid stagnation zones within the micron-scale directional through-hole network, and establishes a rigid linkage between upstream and downstream process steps at the fluid dynamics level.

[0045] Based on the forced convection exchange mechanism established by high-pressure infiltration and low-pressure extrusion, fluid acoustic energy intervention is introduced during the phase-controlled ultrasonic and alternating pressure coupling leaching and transfer stage. The specific implementation details of the low-pressure phase-locked control and acoustic cavitation excitation mechanism are discussed and analyzed.

[0046] S304, Transient Pressure Monitoring and Low-Pressure Phase-Locked Triggering. The control system acquires transient pressure data in real time through a pressure sensor installed inside the pressure leaching vessel. The pressure sensor specifically employs a piezoresistive corrosion-resistant pressure sensor or a thin-film isolated pressure transmitter. The ultrasonic transmitting array specifically employs a piezoelectric ceramic ultrasonic transducer array attached to the outer wall of the pressure leaching vessel. The control system performs a high-frequency comparison between the transient pressure data and a set low-pressure threshold range. When the transient pressure data decreases and fully enters the set low-pressure threshold range, the control system sends a drive electrical signal to the ultrasonic transmitting array. The ultrasonic transmitting array receives the drive electrical signal and emits high-frequency ultrasonic pulses within the low-pressure threshold phase range. To ensure effective triggering of the subsequent acoustic cavitation effect, the frequency parameter of the high-frequency ultrasonic pulse is set in the range of 20kHz to 40kHz, and the ultrasonic power density parameter is set in the range of 0.5W / cm² to 2.0W / cm². The high-frequency ultrasonic pulse emission action forms a strict phase-locked coupling with the low-pressure trough range of the alternating pressure field. Phase-locked coupling logic prevents the ultrasonic transmitting array from outputting ineffective acoustic power at the high-pressure peak phase, establishing a precise coordination relationship between the macroscopic pressure alternation law and the microscopic acoustic pulse triggering timing. For the design of the signal analog-to-digital conversion circuit of the pressure sensor and the drive power supply of the piezoelectric ceramic ultrasonic transducer array, those skilled in the art can match them with conventional industrial automatic control standards. Hardware circuit design and sensor matching are well-known technologies in the field and will not be elaborated further in this specification.

[0047] S305, Evolution of the Acoustic Cavitation Phase Transition Dynamics Model. High-frequency ultrasonic pulses generated by the emission penetrate the outer wall of the pressurized leaching vessel and propagate within the aqueous leachate. The macroscopic physical environment inside the pressurized leaching vessel, located in a low-pressure threshold range, causes the local static pressure of the aqueous leachate to approach the saturated vapor pressure. This near-saturated vapor pressure significantly reduces the energy threshold required for the aqueous leachate to undergo a cavitation phase transition. The periodic local negative pressure induced by the high-frequency ultrasonic pulses promotes the generation of numerous cavitation microbubbles within the aqueous leachate. The nonlinear dynamic expansion and collapse process of these cavitation microbubbles within the fluid medium is strictly constrained by the Rayleigh-Plesset equations. The physical and mathematical expressions constraining the dynamic behavior are defined as follows: In the formula, Represents the instantaneous expansion radius of the cavitation microbubble. Represents the dynamic evolution time. The fluid density representing the aqueous phase leachate. This represents the saturated vapor pressure of the aqueous leachate at the current operating temperature. This represents the transient macroscopic static pressure formed by the alternating pressure field. This represents the transient acoustic pressure exerted by a high-frequency ultrasonic pulse inside a fluid. This represents the liquid-gas surface tension of the aqueous leachate. Due to... When in the low-pressure threshold phase, the pressure difference driving force on the right side of the formula is maximized, which enables cavitation microbubbles to achieve rapid nucleation and rapid growth at lower ultrasonic power.

[0048] S306, Microjet Cell Disruption and Forced Interface Stripping. Driven by a low-pressure environment and high-frequency ultrasonic pulses, cavitation microbubbles rapidly expand within the micron-scale directional interconnected pore network of the roasted sand particles. As the high-frequency ultrasonic pulses transition to a positive pressure half-cycle or begin to rise under the drive of a programmable booster pump, the cavitation microbubbles within the micron-scale directional interconnected pore network experience severe environmental pressure differentials and undergo instantaneous collapse. The collapsed cavitation microbubbles generate high-speed microjet streams and microscopic shock waves pointing towards the solid inner wall of the micron-scale directional interconnected pore network. The high-speed microjet streams directly impact the solid reaction residues (i.e., insoluble byproducts such as iron oxide, manganese dioxide, or calcium carbonate generated during the initial roasting stage) adhering to the inner wall of the micron-scale directional interconnected pore network, as well as the diffusion boundary layer encapsulating the surface of the fresh mineral phase. The localized mechanical shear force generated by the impact forcibly strips the solid reaction residues from the inner wall of the micron-scale directional interconnected pore network. This stripping action exposes the fresh tungsten-bearing mineral phase interface at the bottom of the pores, which is either not yet fully transformed or in a passivated state. The fresh tungsten-bearing ore phase interface comes into full contact with the aqueous leachate under the intense turbulent disturbance caused by the high-speed microjet, eliminating the local concentration polarization phenomenon at the bottom of the pores and opening up the mass transfer channel for the target component to diffuse freely into the surrounding aqueous leachate.

[0049] Based on the fresh tungsten-bearing ore phase interface exposed by microjet disruption and forced exfoliation, the multiphase synergistic reaction system enters the stage of implementing microscopic mass transfer enhancement and multidentate coordination anti-precipitation chemical mechanisms. The specific implementation details of the mass transfer kinetics evolution and coordination chemical reactions are discussed and analyzed in detail.

[0050] S307, acoustic field-driven spatial configuration reversal of multidentate ligands. An alternating pressure field forces the aqueous leaching solution containing disodium ethylenediaminetetraacetate (EDTA) deep into the micron-scale directional interconnected pore network. To ensure the macroscopic thermodynamic kinetics of the coordination reaction and the solubility of tungstate, the control system maintains the macroscopic leaching temperature inside the pressure leaching vessel within a set range (e.g., 60°C to 95°C). The acoustic cavitation effect triggered by the ultrasonic emission array on the outer wall of the pressure leaching vessel generates microscopic shock waves and a localized transient high-temperature and high-pressure microenvironment within the pores. This transient high-temperature and high-pressure microenvironment transfers hydrodynamic kinetic and thermal energy to the disodium ethylenediaminetetraacetate (EDTA) molecules, causing them to accelerate and overcome their internal rotational potential barrier under the physical shearing action of the microscopic shock waves, resulting in spatial configuration reversal. The spatial extension of the EDTA molecules after configuration reversal increases, and the probability of exposing coordinating atoms increases, providing kinetic space preparation for the subsequent rapid capture of metal impurity cations.

[0051] S308, In-situ Complexation Reaction of Metal Impurity Cations. At the interface of a fresh tungsten-bearing ore phase, under the turbulent elution action of the aqueous leachate, free tungstate ions are released into the aqueous leachate, simultaneously dissociating into metal impurity cations such as calcium, iron, and manganese ions. Disodium ethylenediaminetetraacetate (EDTA) molecules, having undergone spatial configuration inversion, rapidly approach the dissociated metal impurity cations through intense turbulent convection induced by ultrasonic microjets. The effectively complexed anions released from EDTA undergo irreversible in-situ complexation reactions with calcium, iron, and manganese ions. The corresponding chemical reaction equations for these in-situ complexation reactions are as follows: In the formula, Represents calcium ions. The effective complexing anion representing disodium ethylenediaminetetraacetate (EDTA) Represents the anion of calcium ion complex. Represents iron ions. Represents the anion of the iron ion complex. Represents manganese ions. This represents the manganese ion complex anion. In-situ complexation reactions combine free metal impurity cations in the system into stable complexes with large molecular steric hindrance.

[0052] S309, the thermodynamic pathway blocking mechanism for secondary precipitation. In conventional atmospheric pressure leaching of tungsten ore, high concentrations of tungstate ions accumulated within the pores readily combine with free calcium or iron ions to form insoluble calcium or iron tungstate secondary precipitates, which then cover the surface of unreacted mineral particles, leading to a decrease in extraction rate. Because the large molecular stable complexes generated by the in-situ complexation reaction possess extremely high stability constants, the absolute concentration of free metal impurity cations within the aqueous leachate is significantly reduced. This significantly reduced concentration of free metal impurity cations is far below the solubility product constant critical value required for the formation of secondary tungstate precipitation, thus completely blocking the thermodynamic pathway for the combination of metal impurity cations and free tungstate ions. Freed from secondary precipitation interference, the free tungstate ions, following the low-pressure extrusion action established by the alternating pressure field, smoothly diffuse unidirectionally from the micron-scale directional interconnected pore network to the macroscopic aqueous phase of the pressure leaching vessel, achieving efficient liquid-phase transfer of the target product, sodium tungstate. For the specific calculation and determination rules of the stability constant of complexes and the solubility product constant of precipitation, those skilled in the art can make conventional deductions in combination with the basic theory of inorganic chemistry. The relevant determination rules are well-known in the field and will not be repeated in the text of the specification.

[0053] The system utilizes the efficient liquid-phase transfer state of sodium tungstate, the target product, within the pressurized leaching vessel, to initiate the solid-liquid separation of the slurry and deep purification of the leachate stage in a multiphase synergistic reaction system. The specific implementation details of the physical separation of the slurry and the chemical purification of the solution are broken down and discussed.

[0054] S401, system depressurization and physical separation of the slurry. After the alternating pressure coordination leaching process reaches the set cycle, the control system sends a depressurization opening command to the servo depressurization valve. The high-pressure state inside the pressure leaching vessel is restored to atmospheric pressure. The discharge pump draws the mixed slurry containing tungsten-rich leachate and solid tailings from the pressure leaching vessel to the solid-liquid separation unit. The solid-liquid separation unit specifically adopts a chamber filter press or a horizontal belt vacuum filter. The solid-liquid separation unit applies mechanical filtration to the mixed slurry; the solid tailings are retained by the filter media, while the tungsten-rich leachate penetrates the filter media and enters the collection tank. To recover the sodium tungstate entrained on the surface of the solid tailings, hot water at a set temperature of 60°C to 80°C is sprayed onto the solid tailings for replacement washing. The washing liquid generated after washing is combined with the tungsten-rich leachate inside the collection tank.

[0055] S402, steric-dependent selective ion exchange purification. The tungsten-rich leachate contains free tungstate ions and stable macromolecular complexes in a complexed state. An infusion pump pumps the tungsten-rich leachate into an ion exchange column. The ion exchange column is filled with a macroporous weakly basic anion exchange resin (specifically, D314 or D301 type resin is used below). The three-dimensional network structure of the macroporous weakly basic anion exchange resin exhibits adsorption selectivity for anions of different spatial sizes. The stable macromolecular complexes in a complexed state are repelled by steric hindrance and cannot enter the internal pores of the macroporous weakly basic anion exchange resin, thus exiting the ion exchange column with the effluent. Smaller free tungstate ions, however, can easily enter the resin pores and undergo an ion exchange reaction with the active groups of the macroporous weakly basic anion exchange resin. The ion exchange reaction corresponds to the following chemical reaction equation: In the formula, This represents a chloride-form macroporous weakly basic anion exchange resin. Represents sodium tungstate molecules, This represents the resin phase after adsorption of tungstate ions. This represents a sodium chloride molecule. The ion exchange reaction immobilizes tungstate ions on a solid resin, achieving deep chemical separation of tungstate ions from stable macromolecular complexes.

[0056] S403, desorption transformation and ammonium paratungstate crystallization. After the ion exchange column reaches adsorption saturation, a desorption pump injects a mixed desorption solution containing ammonium chloride and ammonia into the ion exchange column. The mixed desorption solution undergoes a reverse displacement reaction with the resin phase after adsorbing tungstate ions. The reverse displacement reaction elutes the tungstate ions into the liquid phase and generates an ammonium tungstate solution. The reverse displacement desorption reaction corresponds to the following chemical reaction equation: In the formula, Represents ammonium chloride molecules. This represents ammonium tungstate molecules. The evaporator crystallizer receives the ammonium tungstate solution and heats it for concentration. During this concentration process, ammonia and moisture continuously evaporate from the solution, causing the supersaturation level within the system to gradually increase, eventually precipitating ammonium paratungstate crystals. For the specific regeneration operation of the ion exchange resin and the setting of the temperature and pressure parameters of the evaporator crystallizer, those skilled in the art can refer to conventional tungsten metallurgical separation process manuals for configuration. Resin regeneration operations and evaporation crystallization parameter configurations are well-known techniques in the field and will not be elaborated upon in this specification.

[0057] Based on the aforementioned fluidized bed preheating, molten salt aerosol enhanced roasting, phase-controlled ultrasonic alternating pressure coordination leaching, and subsequent solid-liquid separation and purification processes, the multiphase synergistic reaction system establishes the underlying linkage logic between various technical features throughout the entire process. The synergistic construction mechanism of the core components of the tungsten extraction method based on the coupled molten salt aerosol fluidized bed roasting and phase-controlled ultrasonic alternating pressure leaching is described below.

[0058] S404, Multiphase Physical Structure Synergistic Mechanism. In the tungsten extraction method based on molten salt aerosol fluidized bed roasting and phase-controlled ultrasonic alternating pressure leaching, the micron-scale directional interconnected pore network output from the molten salt aerosol enhanced roasting step constitutes a physical bridge connecting the preceding and following processes. The micron-scale directional interconnected pore network generated by the in-situ vaporization of microcapsule pore-forming agent during the roasting stage directly provides microscopic fluid channels for the aqueous leachate to penetrate into the particle interior in the phase-controlled ultrasonic alternating pressure coordination leaching step. If the micron-scale directional interconnected pore network structure is removed, the alternating pressure field will lose the pore carrier for applying the mechanical pumping effect. In this case, the pressure alternation inside the pressure leaching vessel not only fails to drive the aqueous leachate deep into the core of the mineral powder particles, but also, due to the large amount of easily soluble salts and finely fragmented conversion products on the surface of the roasted sand particles, simple pressure fluctuations can easily cause particle surface peeling and slurry mud formation, thereby blocking the leaching channels. Similarly, without the driving force of the alternating pressure field, the solution inside the micron-sized oriented interconnected pore network will stagnate, preventing the dissolved sodium tungstate product from transferring to the surrounding liquid phase. A mutually dependent physical structural relationship is established between the pore-forming operation performed by the microcapsule pore-forming agent and the alternating pressure driving force.

[0059] S405, a phase-locked synergistic mechanism combining fluid dynamics and sonochemical energy fields. A precise temporal logic coupling is established between the control system and the ultrasonic transmitting array. When the alternating pressure field is in the high-pressure phase, the ultrasonic transmitting array remains silent to avoid the suppression of cavitation effects by the high-pressure physical environment. When the alternating pressure field enters the low-pressure threshold range, the local static pressure of the aqueous leachate approaches the saturated vapor pressure as the macroscopic pressure decreases, resulting in a significant reduction in the cavitation threshold required to induce sonochemical cavitation. The control system synchronously triggers high-frequency ultrasonic pulses within the low-pressure threshold range, causing the generated cavitation microbubbles to violently collapse within the micron-scale directional through-pore network. The resulting microjets perform impact stripping on solid reaction residues such as iron oxide, manganese dioxide, or calcium carbonate attached to the inner wall, exposing fresh tungsten-bearing mineral phase interfaces and providing reaction sites for the in-situ complexation reaction of disodium ethylenediaminetetraacetate. The phase-locked synergy between the macroscopic pressure alternation and the microscopic acoustic pulses opens up a cross-scale mass transfer channel from fluid permeation to sonochemical wall disruption.

[0060] S406, a thermodynamic equilibrium and interfacial mass transfer coupled anti-precipitation mechanism. During the roasting stage, sodium tungstate and dissociated calcium, iron, and manganese ions generated from wolframite and scheelite components are initially retained within a micron-sized directional interconnected pore network. To address the secondary precipitation problem induced by high-concentration ion accumulation within the pores, a deep coupling of acoustic field-driven dynamics and coordination chemistry anti-precipitation mechanisms is employed. High-frequency ultrasonic pulses induce microscopic shock waves that cause disodium ethylenediaminetetraacetate to overcome its internal rotational potential barrier and undergo spatial configuration inversion, thereby rapidly capturing metal impurity cations and forming a macromolecular stable complex. This macromolecular stable complex suppresses the absolute concentration of free metal impurity cations below the critical value of the precipitation solubility product constant. The ion concentration suppression effect, combined with the low-pressure expansion extrusion action established by the alternating pressure field, ensures the unidirectional transfer of the target product, sodium tungstate, into the macroscopic aqueous phase. Phase-controlled ultrasonic operation, alternating pressure fluid drive, and coordination chemical reaction together construct a defense system that blocks the thermodynamic path of secondary precipitation, solving the technical bottleneck of solid-phase diffusion resistance and limited leaching rate in tungsten extraction from mixed tungsten ores.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching coupled together, characterized in that, Includes the following steps: S100, the mixed tungsten ore powder is introduced into the fluidized bed reactor, hot carrier gas is blown into the fluidized bed reactor to keep the mixed tungsten ore powder in a fluidized suspension state, and the mixed tungsten ore powder is preheated to the preset roasting temperature zone. S200 involves heating a low-melting-point alkali metal eutectic salt system containing soda ash and microcapsule pore-forming agent to a molten state, atomizing the molten low-melting-point alkali metal eutectic salt system into a boiling reactor to form eutectic salt aerosol droplets, which spread on the surface of the mixed tungsten ore powder to form a dynamic reaction liquid film, and the microcapsule pore-forming agent vaporizes in situ within the dynamic reaction liquid film, and constructs a micron-scale directional through-hole network in the roasted sand generated by the synchronous deconstruction reaction of the mixed tungsten ore powder. S300: The calcined sand is transferred to a pressure leaching vessel. Aqueous leaching solution and multidentate ligands are injected into the pressure leaching vessel. A periodic alternating pressure field is constructed in the pressure leaching vessel, which forces the aqueous leaching solution to penetrate into the micron-scale directional through-pore network. When the alternating pressure field drops to the low pressure threshold range, a high-frequency ultrasonic pulse is triggered to induce acoustic cavitation. The multidentate ligands penetrate deep into the micron-scale directional through-pore network and undergo a complexation reaction with the metal impurity cations to generate macromolecular stable complexes. S400, the internal pressure of the pressure leaching vessel is vented, and the mixed slurry inside the pressure leaching vessel is transported to the solid-liquid separation unit to perform solid-liquid separation to obtain tungsten-rich leachate. The tungsten-rich leachate is introduced into the ion exchange column for separation and purification.

2. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S100, a gas distribution plate is installed at the bottom of the fluidized bed reactor, and the blower blows hot carrier gas into the fluidized bed reactor from bottom to top through the gas distribution plate; the apparent gas velocity of the hot carrier gas is greater than the minimum fluidization velocity corresponding to the mixed tungsten ore powder; the hot carrier gas and the mixed tungsten ore powder undergo gas-solid two-phase high-frequency heat conduction, keeping the mixed tungsten ore powder in a fluidized suspension state constant in the preset roasting temperature range of 550°C to 650°C.

3. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S200, a supersonic dual-fluid nozzle array is installed on the side wall of the boiling reactor. The supersonic dual-fluid nozzle array receives high-pressure compressed gas and a low-melting-point alkali metal eutectic salt system in a molten state. The high-speed shearing and collision force provided by the high-pressure compressed gas disperses the low-melting-point alkali metal eutectic salt system into eutectic salt aerosol droplets. After the eutectic salt aerosol droplets come into contact with the surface of the tungsten ore powder, they trigger phase change wetting behavior, rapidly spread out and connect to form a fully encapsulated dynamic reaction liquid film.

4. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S200, the core of the microcapsule pore-forming agent is an inorganic ammonium salt compound, and the outer shell of the microcapsule pore-forming agent is a high-temperature resistant inert wall material. The outer shell of the microcapsule pore-forming agent inside the dynamic reaction liquid film melts and ruptures across the melting point of the wall material, exposing the core of the microcapsule pore-forming agent and triggering a violent thermal decomposition reaction that releases gaseous substances and evolves into bubble nuclei. The gaseous substances overcome the surface tension constraint generated by the dynamic reaction liquid film and the external hydrostatic pressure resistance to escape to the outside, opening up physical exhaust channels inside the dynamic reaction liquid film. Physical exhaust channels interweave and combine within the shell of solid calcined sand products, forming a micron-sized directional through-hole network radiating from the particle core to the outer surface.

5. The method for extracting tungsten by coupled chemical leaching and enhanced roasting of mixed tungsten ore according to claim 1, characterized in that, In step S200, the mixed tungsten powder contains wolframite and scheelite components; the wolframite component reacts with oxygen and sodium carbonate in the low-melting-point alkali metal eutectic salt system to release sodium tungstate through a gas-liquid-solid three-phase oxidation deconstruction reaction; the scheelite component reacts with sodium carbonate through a reversible displacement reaction to release sodium tungstate; the sodium tungstate generated by the reaction directly dissolves and becomes free inside the dynamic reaction liquid film, and the free sodium tungstate detaches from the original solid-phase reaction interface and diffuses into the liquid phase to the outside, blocking the formation path of the dense solid coating layer and achieving synchronous lattice deconstruction.

6. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S300, a programmable booster pump and a servo pressure relief valve are connected to the fluid circuit of the pressure leaching vessel. The control system alternately sends high-frequency alternating execution commands to control the programmable booster pump and the servo pressure relief valve to operate in conjunction, constructing a sinusoidal oscillating alternating pressure field inside the pressure leaching vessel. When the alternating pressure field is at the high-pressure threshold phase, the external high-pressure fluid statically compresses the aqueous phase leachate into the depths of the micron-level directional through-hole network and simultaneously compresses the residual microbubbles inside the pores. When the alternating pressure field is at the low-pressure threshold phase, the compressed microbubbles lose the external high-pressure constraint and undergo instantaneous volume expansion. The volume expansion generates a repulsive force that squeezes the leaching medium inside the micron-level directional through-hole network out of the pores, establishing a forced convection exchange mechanism.

7. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S300, an ultrasonic transmitting array is arranged on the outer wall of the pressure leaching vessel; the control system collects transient pressure data inside the pressure leaching vessel and performs high-frequency comparison with the set low-pressure threshold range; when the transient pressure data drops into the low-pressure threshold range, the control system sends a driving electrical signal to the ultrasonic transmitting array to trigger the high-frequency ultrasonic pulse emission action and form a phase-locked coupling with the low-pressure trough range of the alternating pressure field; the high-frequency ultrasonic pulse induces periodic local negative pressure, causing a large number of cavitation microbubbles to be generated inside the aqueous phase leachate.

8. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 7, characterized in that, Cavitation microbubbles undergo instantaneous collapse under intense environmental pressure differential during the positive pressure half-cycle transition of high-frequency ultrasonic pulses. In the collapse state, cavitation microbubbles generate high-speed microjets pointing towards the inner wall of the micron-sized directional interconnected pore network solid phase. The high-speed microjets directly impact and peel off the solid reaction residues attached to the inner wall of the micron-sized directional interconnected pore network, exposing fresh tungsten-bearing mineral phase interface to eliminate local concentration polarization and open up the ion diffusion mass transfer channels of tungstate ions to the surrounding aqueous leachate.

9. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S300, high-frequency ultrasonic pulses induce a local transient high-temperature and high-pressure microenvironment, transferring hydrodynamic kinetic energy to cause the multidentate ligands to overcome the internal rotational barrier and undergo spatial configuration reversal. The spatial configuration reversal causes the multidentate ligands to dissociate effectively, and the anions that have been effectively complexed with the metal impurity cations that have dissociated from the fresh tungsten-bearing ore phase interface undergo an irreversible in-situ complexation reaction. The in-situ complexation reaction generates a large molecular stable complex, which significantly reduces the absolute concentration of free metal impurity cations in the aqueous leachate, suppresses the ion concentration below the critical value of the solubility product constant, and completely blocks the thermodynamic path of metal impurity cations combining with free tungstate ions to form secondary precipitation.

10. The method for extracting tungsten from mixed tungsten ore through enhanced roasting and chemical leaching according to claim 1, characterized in that, In step S400, the tungsten-rich leachate contains free tungstate ions and macromolecular stable complexes; the ion exchange column is filled with macroporous weakly basic anion exchange resin; the macromolecular stable complexes are repelled by the steric hindrance effect of the three-dimensional network framework structure of the macroporous weakly basic anion exchange resin and cannot enter the internal channels, and are discharged from the ion exchange column with the effluent; the free tungstate ions enter the resin channels and undergo ion exchange reactions with the active groups, and the tungstate ions are fixed in the solid resin to achieve deep chemical separation from the macromolecular stable complexes.

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