Method and device for purifying high-purity boron oxide

Abstract

The invention relates to the technical field of preparation of high-purity boron oxide, and discloses a purification method of high-purity boron oxide and a device thereof, and the purification method comprises the following steps: step 1, mixing crude boron oxide with a liquid metal alloy, and dissolving metal impurities through gradient temperature control; 2, applying ultrasonic treatment to the mixed system, introducing a vortex field, and stripping impurities on the surface of the boron oxide; 3, a liquid metal phase and a boron oxide solid phase are separated through cooperation of a magnetic field and a pulse high-voltage electrostatic field; 4, non-metal ion impurities are removed through a gradient porous ceramic adsorption bed; and step 5, melting boron oxide in vacuum and carrying out gradient cooling crystallization. By adopting the technical scheme of a Ga-I n-Bi-Er quaternary liquid alloy system, the technical effect of selective targeted removal of metal impurities is achieved, and compared with a liquid metal system depending on single phase solubility difference in the prior art, the defect that efficient chelating and dynamic settling separation of the impurities cannot be achieved at the same time is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity boron oxide preparation, in particular to a method and a device for purifying high-purity boron oxide. Background Art

[0002] Boron oxide, a key raw material for high-performance glass, optical devices, and semiconductor packaging materials, has a purity that directly impacts the transmittance, dielectric properties, and thermal stability of end products. Especially in high-end applications, there are strict limits on the residual amounts of metallic impurities and non-metallic ions in boron oxide, which must meet ultra-low trace requirements. However, boron oxide, either in natural raw materials or as an industrial byproduct, is often accompanied by complex impurity systems, including metal oxide microcrystal inclusions and ion adsorption layers. Traditional purification processes make it difficult to achieve the simultaneous and deep removal of multiple impurities.

[0003] In the existing technology, the liquid metal solvent method separates metal impurities through high-temperature dissolution and cooling sedimentation. However, it relies on the difference in the solubility of metals in the liquid phase, has poor selectivity for certain ions with similar solubility to the matrix, and cannot effectively intercept nanoscale non-metallic ions. For example, when using conventional binary alloys, the removal rate of metal impurities is significantly insufficient, and the sudden change in liquid metal viscosity during sedimentation can easily lead to fluctuations in separation efficiency. In addition, although traditional adsorption methods can partially adsorb specific ions, their single pore structure is easily clogged by micron-sized dust, and the dynamic adsorption capacity decays rapidly with operating time.

[0004] Existing technologies for desorbing nanoscale impurities from boron oxide surfaces typically use mechanical or chemical treatments, but the former can easily introduce lattice damage, while the latter poses environmental risks. Single-field separation techniques, lacking a multi-field synergy mechanism, struggle to balance the differences in separation kinetics between different impurity types, leading to widespread problems such as impurity reagglomeration and grain boundary segregation. For example, in fixed-field separation devices, it's difficult to simultaneously optimize the separation efficiency of magnetic impurities and non-magnetic charged particles. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method and apparatus for purifying high-purity boron oxide, which solves the problems of low efficiency in simultaneous removal of metal and non-metallic impurities and difficulty in desorption of nano-scale surface impurities in traditional processes.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for purifying high-purity boron oxide, comprising the following steps:

[0007] Step 1: Mixing crude boron oxide with liquid metal alloy and dissolving metal impurities through gradient temperature control;

[0008] Step 2: Ultrasonic treatment is applied to the mixed system and an eddy current field is introduced to remove impurities on the surface of the boron oxide;

[0009] Step 3: Using a magnetic field and a pulsed high-voltage electrostatic field to synergistically separate the liquid metal phase and the boron oxide solid phase;

[0010] Step 4: removing non-metallic ion impurities through a gradient porous ceramic adsorption bed;

[0011] Step 5: vacuum melt the boron oxide and perform gradient cooling crystallization.

[0012] Furthermore, the integrated process of liquid metal selective dissolution, multi-physical field synergistic separation, and gradient adsorption refining overcomes the limitations of traditional single processes. Liquid metal achieves dynamic dissolution and sedimentation of metallic impurities through chemical chelation and temperature control; ultrasonic cavitation and eddy current fields synergistically strip nanoscale surface impurities; magnetoelectric coupling separation technology simultaneously removes magnetic and charged non-magnetic impurities; gradient porous ceramics achieve targeted adsorption of non-metallic ions through pore size classification and functional modification; and vacuum melting and gradient cooling eliminate lattice defects, ultimately yielding ultra-high-purity boron oxide.

[0013] Preferably, the liquid metal alloy in step 1 is a Ga-In-Bi-Er quaternary alloy, which comprises, by mass percentage, 68-72% Ga, 22-26% In, 5-8% Bi, and 0.5-1.2% Er.

[0014] Furthermore, Er element is introduced as a chelating agent, and its 3d electron orbital is closely related to Fe 3+ / Ca 2+ The 4s orbital of Ga-In-Bi forms a stable coordination bond, significantly improving the dissolution efficiency of metal impurities; the Ga-In-Bi ternary system provides a low melting point and high fluidity, ensuring rapid phase separation of liquid metal under gradient temperature control.

[0015] Preferably, the gradient temperature control in step 1 includes:

[0016] The dissolution stage temperature is 215-225°C, the stirring rate is 300-400 rpm, and the time is 45-60 minutes;

[0017] During the cooling stage, the temperature is lowered to 80-85°C at a rate of 1.5-2.5°C / min.

[0018] Furthermore, during the high-temperature dissolution stage at 215-225°C, the low viscosity of liquid metal (≤2 mPa·s) is utilized to accelerate mass transfer; a gradient cooling of 1.5-2.5°C / min induces a sudden increase in the viscosity of the liquid metal (≥5 mPa·s), achieving rapid stratification of the impurity phase through Stokes' sedimentation law.

[0019] Preferably, the ultrasound parameters in step 2 are:

[0020] Frequency 20-40kHz, power density 35-45W / cm 3, pulse duty cycle 50-70%, synchronous introduction of nitrogen microbubbles, flow rate 0.4-0.6L / min.

[0021] Furthermore, the 20-40kHz ultrasonic frequency matches the acoustic impedance characteristics of liquid metal, generating local cavitation bubble collapse pressure, effectively destroying the impurity coating on the surface of boron oxide; nitrogen microbubbles (diameter 50-100μm) serve as cavitation nuclei, enhancing the cavitation effect and inhibiting the agglomeration of boron oxide particles.

[0022] Preferably, impurities are separated by the synergistic effect of a magnetic field and a pulsed high-voltage electrostatic field, wherein the magnetic field strength and the electrostatic field voltage are in a negatively correlated linear relationship, and the negatively correlated linear relationship is U=-18.75B+3.5, wherein B is the magnetic field strength and U is the pulsed high-voltage electrostatic field voltage.

[0023] Furthermore, the magnetoelectric parameter coupling equation (U = -18.75B + 3.5) suppresses the re-adsorption of impurity particles during the separation process through the dynamic balance of Lorentz and Coulomb forces. The negative correlation between magnetic field strength B and voltage U ensures the simultaneous and efficient separation of magnetic impurities (such as Fe3O4) and non-magnetic charged particles (such as Al2O3).

[0024] Preferably, the gradient porous ceramic adsorption bed in step 4 comprises:

[0025] Upper layer of Al2O3 ceramic, pore size 0.5-1.0μm, thickness 8-12mm;

[0026] The lower layer is ZrO2 ceramic with a pore size of 0.1-0.2 μm, loaded with 8-12 wt% zirconium phosphate nanoclusters, and modified with mercaptosilane, with a thickness of 18-22 mm.

[0027] Furthermore, the upper macroporous Al2O3 intercepts micron-sized dust particles to avoid clogging the lower mesoporous structure; the lower ZrO2 is formed by zirconium phosphate nanoclusters (Zr 4+ -SO4 2- coordination) with mercaptosilane (mercapto-Cl - Hydrogen bond adsorption) dual-functional modification to achieve SO4 2- With Cl - Simultaneous chemical adsorption of ions.

[0028] Preferably, the vacuum melting temperature in step 5 is 455-465°C and the vacuum degree is ≤5×10 -3 Pa, gradient cooling includes:

[0029] The first stage is cooling from 465°C to 300°C at 8-10°C / min;

[0030] The second stage is cooling from 300°C to 150°C at 2-3°C / min.

[0031] Furthermore, the vacuum environment suppresses the vaporization residue of impurity elements (such as Na and K); the gradient cooling strategy obtains boron oxide crystals with pure grain boundaries by controlling the grain boundary migration rate (rapid cooling in the first stage suppresses grain coarsening, and slow cooling in the second stage reduces lattice defects).

[0032] Preferably, the pulse high voltage electrostatic field parameters in step 3 are:

[0033] Output voltage -12±3kV, frequency 8-12Hz, duty cycle 25-35%.

[0034] Furthermore, the 8-12 Hz pulse frequency matches the charge relaxation time of the impurity particles, avoiding adsorption failure caused by charge accumulation; the 25-35% duty cycle optimizes the balance between electric field energy consumption and separation efficiency.

[0035] Preferably, the operating conditions of the adsorption bed in step 4 are:

[0036] The fluidizing gas velocity is 0.8-1.2 m / s, the bed temperature is 180-200°C, and the adsorption time is 20-30 minutes.

[0037] Furthermore, a fluidizing gas velocity of 0.8-1.2 m / s ensures uniform distribution of boron oxide particles within the adsorption bed; an operating temperature of 180-200° C. increases the density of adsorption active sites of zirconium phosphate and mercaptosilane through thermal activation.

[0038] A device for preparing high-purity boron powder, comprising:

[0039] Liquid metal processing module: nitrogen-protected stirred tank, gradient temperature control system;

[0040] Ultrasonic eddy current module: including pulse ultrasonic generator, spiral guide plate and microbubble injection unit;

[0041] Magnetoelectric separation module: integrates Halbach magnetic array centrifuge and pulsed high-voltage electrostatic field generator;

[0042] Gradient adsorption module: Contains double-layer porous ceramic filter element and fluidized bed heating system;

[0043] Vacuum crystallization module: includes vacuum induction furnace, gradient cooling device and online purity detection unit.

[0044] Furthermore, the modular design of the device realizes closed-loop control of the entire process. The Halbach magnetic array centrifuge generates a gradient magnetic field through a permanent magnet array (NdFeB, remanence 1.3-1.4T); the pulsed high-voltage electrostatic field generator and the parameter linkage controller match the magnetoelectric parameters in real time; the double-layer ceramic filter element realizes adsorbent regeneration and replacement through a quick-release structure.

[0045] The present invention provides a method and apparatus for purifying high-purity boron oxide, which has the following beneficial effects:

[0046] 1. The present invention adopts the technical solution of Ga-In-Bi-Er quaternary liquid alloy system to achieve the technical effect of selective targeted removal of metal impurities. Compared with the liquid metal system in the prior art that relies on the solubility difference of a single phase, it solves the deficiency that it cannot simultaneously achieve efficient chelation and dynamic sedimentation separation of impurities.

[0047] 2. The present invention adopts a gradient porous ceramic double-layer modified structure technology solution to achieve the technical effect of simultaneous adsorption of non-metallic ions and flow channel anti-blocking. Compared with the single pore size adsorption bed design in the existing technology, it solves the shortcomings of rapid attenuation of adsorption capacity and poor ion selectivity caused by clogging of micron-sized particles.

[0048] 3. The present invention adopts the ultrasonic cavitation-eddy current shear synergistic stripping technology solution to achieve the technical effect of efficient desorption of nano-scale surface impurities. Compared with the single ultrasonic cavitation treatment mode in the existing technology, it solves the problem of uneven energy density distribution leading to a high residual rate of impurity inclusions.

[0049] 4. The present invention adopts a dynamic linkage separation technology solution of magnetoelectric parameters to achieve the technical effect of synchronous separation of multiple types of charged impurities. Compared with the fixed field strength separation device in the existing technology, it solves the shortcomings of impurity re-agglomeration and separation efficiency fluctuation caused by force field imbalance. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flow chart of the method of the present invention;

[0051] Figure 2 This is a system framework diagram of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Please see the attached Figure 1 :

[0054] Example 1

[0055] Step 1: Dynamic Solvation of Liquid Metal

[0056] Liquid alloy preparation: prepare a quaternary alloy with mass ratio of Ga70%, In24%, Bi6.5%, Er0.85%, and heat it in a vacuum induction furnace (vacuum degree 8×10 -3 Pa) was melted (330°C) with a stirring rate of 350 rpm for 40 minutes, and then ground into 2 mm particles after cooling.

[0057] Raw material pretreatment: Crude B2O3 was processed by a jet mill (pressure 1.0 MPa) to D50 = 40 μm.

[0058] Gradient temperature controlled dissolution: alloy and B2O3 are mixed at a ratio of 1:3.0 in a nitrogen-protected stirred tank:

[0059] Dissolution stage: heat to 220°C, stir at 350 rpm, and maintain for 50 minutes;

[0060] Cooling stage: cool down to 82°C at 2.0°C / min and let stand for 35 minutes to separate layers.

[0061] Step 2: Ultrasonic-eddy current synergistic cavitation stripping

[0062] Ultrasonic treatment: Apply 30kHz pulsed ultrasound (power density 40W / cm 3 , duty cycle 60%), pulse interval 0.5 s, and nitrogen microbubbles (flow rate 0.5 L / min, diameter 75 μm) were introduced synchronously.

[0063] Vortex enhancement: A 50° inclination spiral guide plate was set in the reactor, and the stirring blade speed was adjusted to 1000 rpm (Reynolds number 5000).

[0064] Termination control: Stop when the turbidity sensor detects turbidity ≤ 50NTU.

[0065] Step 3: Separation of magnetic-electric timing coupling

[0066] Magnetic field separation: start the Halbach magnetic array centrifuge (magnetic field strength 0.9 T, rotation speed 2000 rpm), and simultaneously apply a -13.4 kV pulsed high-voltage electrostatic field (frequency 10 Hz, duty cycle 30%) for 25 minutes.

[0067] Step 4: Gradient porous ceramic adsorption refining

[0068] Adsorption bed filling:

[0069] Upper layer Al2O3 ceramic: pore size 0.75μm, thickness 10mm;

[0070] Lower ZrO2 ceramic: pore size 0.15 μm, loaded with 10 wt% zirconium phosphate nanoclusters, mercaptosilane modification density 4 groups / nm 2 , thickness 20mm.

[0071] Dynamic adsorption: B2O3 powder flows through the adsorption bed (temperature 190°C) at a gas velocity of 1.0 m / s for 25 minutes.

[0072] Step 5: Vacuum gradient melt recrystallization

[0073] Vacuum melting: in a vacuum induction furnace (vacuum degree 4×10 -3 Pa) to 460 ° C and keep warm for 30 minutes.

[0074] Gradient cooling:

[0075] Stage 1: cooling at 9°C / min to 300°C (argon flow rate 6.5 L / min);

[0076] Second stage: cooling to 150°C at 2.5°C / min.

[0077] Example 2

[0078] Step 1: Dynamic Solvation of Liquid Metal

[0079] Liquid alloy preparation: Ga72%, In22%, Bi8%, Er1.2%, melting temperature 350°C, stirring speed 400 rpm, time 45 minutes.

[0080] Gradient temperature-controlled dissolution: alloy and B2O3 are mixed at a ratio of 1:3.2, dissolution temperature is 225℃, and cooling rate is 2.5℃ / min to 85℃.

[0081] Step 2: Ultrasonic-eddy current synergistic cavitation stripping

[0082] Ultrasonic parameters: 40kHz, power density 45W / cm 3 , duty cycle 70%, nitrogen microbubble flow rate 0.6L / min.

[0083] Vortex enhancement: stirring blade speed 1200 rpm (Reynolds number 5500).

[0084] Step 3: Separation of magnetic-electric timing coupling

[0085] The magnetic field strength is 0.8T, corresponding to the voltage U=-11.5kV (calculated as U=-18.75B+3.5), the frequency is 12Hz, and the duty cycle is 35%.

[0086] Step 4: Gradient porous ceramic adsorption refining

[0087] Upper layer Al2O3: pore size 1.0 μm, thickness 12 mm;

[0088] Lower ZrO2: pore size 0.2μm, loaded with 12wt% zirconium phosphate, mercaptosilane modification density 5groups / nm 2 , thickness 22mm.

[0089] Adsorption conditions: gas velocity 1.2 m / s, bed temperature 200°C, time 30 minutes.

[0090] Step 5: Vacuum gradient melt recrystallization

[0091] Melting temperature 465℃, vacuum degree 5×10 -3 Pa;

[0092] Gradient cooling: first stage 10℃ / min to 300℃, second stage 3℃ / min to 150℃.

[0093] Example 3

[0094] Step 1: Dynamic Solvation of Liquid Metal

[0095] Liquid alloy preparation: Ga68%, In26%, Bi5%, Er0.5%, melting temperature 300°C, stirring speed 300 rpm, time 60 minutes.

[0096] Gradient temperature-controlled dissolution: alloy and B2O3 are mixed at a ratio of 1:2.8, dissolution temperature is 215℃, and cooling rate is 1.5℃ / min to 80℃.

[0097] Step 2: Ultrasonic-eddy current synergistic cavitation stripping

[0098] Ultrasonic parameters: 20kHz, power density 35W / cm 3 , duty cycle 50%, nitrogen microbubble flow rate 0.4L / min.

[0099] Vortex enhancement: stirring blade speed 800 rpm (Reynolds number 4500).

[0100] Step 3: Separation of magnetic-electric timing coupling

[0101] The magnetic field strength is 1.0 T, corresponding to the voltage U=-15.25 kV, the frequency is 8 Hz, and the duty cycle is 25%.

[0102] Step 4: Gradient porous ceramic adsorption refining

[0103] Upper layer Al2O3: pore diameter 0.5μm, thickness 8mm;

[0104] Lower ZrO2: pore size 0.1 μm, loaded with 8 wt% zirconium phosphate, mercaptosilane modification density 3 groups / nm 2 , thickness 18mm.

[0105] Adsorption conditions: gas velocity 0.8 m / s, bed temperature 180°C, time 20 minutes.

[0106] Step 5: Vacuum gradient melt recrystallization

[0107] Melting temperature 455℃, vacuum degree 5×10 -3 Pa;

[0108] Gradient cooling: first stage 8℃ / min to 300℃, second stage 2℃ / min to 150℃.

[0109] Comparative Example 1 (Removal of Er element)

[0110] Compared with Example 1, the difference is:

[0111] In step 1, the liquid metal alloy does not contain Er element, and is adjusted to Ga70.85%, In24%, and Bi5.15% (total mass percentage 100%). The remaining steps and parameters are the same.

[0112] Purpose of comparison: To verify the criticality of Er chelation in the removal of metal impurities.

[0113] Comparative Example 2 (Er content exceeds the upper limit)

[0114] Compared with Example 1, the difference is:

[0115] In step 1, the Er content of the liquid metal alloy is adjusted to 1.5% (exceeding the upper limit of 1.2% in claim 2), and the corresponding Ga is adjusted to 68.5%, In 24%, and Bi 6%. The remaining steps and parameters are the same.

[0116] Purpose of comparison: To verify the effect of Er element content exceeding a reasonable range on the fluidity of liquid metal and impurity sedimentation efficiency.

[0117] Comparative Example 3 (omitting eddy current field synergy)

[0118] Compared with Example 1, the difference is:

[0119] In step 2, only ultrasonic treatment was applied without introducing a vortex field (the spiral guide plate was removed, the stirring rate was reduced to 200 rpm, and the Reynolds number was <2000). The remaining steps and parameters were the same.

[0120] Purpose of comparison: To verify the necessity of the synergistic effect of ultrasonic cavitation and eddy current shear force for surface impurity removal.

[0121] Comparative Example 4 (no dynamic linkage of magnetoelectric parameters)

[0122] Compared with Example 1, the difference is:

[0123] In step 3, the magnetic field intensity is fixed at 0.9 T, the pulsed high-voltage electrostatic field voltage is fixed at -10 kV (not adjusted according to U = -18.75B + 3.5), and the remaining steps and parameters are the same.

[0124] Purpose of comparison: To verify the key role of the dynamic linkage equation of magnetoelectric parameters (U=-18.75B+3.5) in inhibiting impurity reagglomeration.

[0125] Comparative Example 5 (gradient porous ceramic only single layer structure)

[0126] Compared with Example 1, the difference is:

[0127] In step 4, the adsorption bed only uses a single layer of Al2O3 ceramic (pore size 0.75 μm, thickness 30 mm), and no lower layer of ZrO2 ceramic is set. The remaining steps and parameters are the same.

[0128] Purpose of comparison: To verify the irreplaceable nature of gradient pore size and bifunctional modification for the simultaneous adsorption of non-metal ions.

[0129] Comparative Example 6 (Vacuum Melting without Gradient Cooling)

[0130] Compared with Example 1, the difference is:

[0131] In step 5, the gradient cooling was cancelled and a single cooling rate (5°C / min from 460°C to 150°C) was adopted. The remaining steps and parameters were the same.

[0132] Purpose of comparison: To verify the necessity of gradient cooling strategy for grain boundary defect control.

[0133] Experiment 1: Verification of the chelation effect of liquid metal Er element

[0134] Experimental procedures

[0135] Sample preparation:

[0136] Take 10 g of each of the boron oxide solid phase samples treated in Examples 1-3 (alloys containing Er), Comparative Example 1 (alloy without Er), and Comparative Example 2 (Er overlimit alloy), dissolve them in nitric acid (5% v / v), and remove insoluble matter through a 0.22 μm filter membrane.

[0137] Metal impurity content test:

[0138] ICP-MS (Inductively Coupled Plasma Mass Spectrometer, ThermoiCAPQc) was used to detect the concentrations of Fe and Ca ions in the filtrate and calculate the removal rate:

[0139] Removal rate (%) = (initial impurity concentration - concentration after treatment) / initial concentration × 100

[0140] Sedimentation time determination:

[0141] Liquid metal and crude boron oxide were mixed according to the proportions in Example 1 and placed in a transparent quartz tube. The interface delamination time between the liquid metal phase and the impurity phase (from the start of cooling to the time when the interface became clear) was recorded using a high-speed camera (Phantom VEO410L).

[0142] Liquid metal viscosity test:

[0143] The dynamic viscosity of liquid metal at different temperatures (shear rate 100s) was measured using a rotational rheometer (Anton Paar MCR302). -1 ).

[0144] Data collection:

[0145] Each experiment was repeated 3 times, and the average value was taken with one decimal place retained.

[0146] Experimental data

[0147] Table 1 Effect of Er element on metal impurity removal rate and sedimentation time

[0148]

[0149]

[0150] Experimental Summary

[0151] In Er-containing liquid metal alloys, the 3d electron orbital of Er element and Fe 3+ / Ca 2+ The Er-containing alloys (Examples 1-3) achieve 25-35% higher Fe and Ca removal rates than the Er-free alloy (Comparative Example 1). Furthermore, the chelation effect induces rapid precipitation of the impurity phase during cooling (settling time is shortened by over 50%).

[0152] When the Er content exceeded the reasonable range (Comparative Example 2), although the chelating effect still existed, the excess Er caused the liquid metal viscosity to increase from 1.8 mPa·s to 5.4 mPa·s at 220°C, significantly inhibiting the mass transfer rate, as evidenced by a prolonged settling time of 24.7 minutes and a 3-7% decrease in impurity removal compared to Example 1. This demonstrates the importance of an optimized Er content range (0.5-1.2%) for balancing chelating ability and fluidity.

[0153] This experiment reveals the dual mechanism of Er in liquid metal systems: chemical chelation through orbital hybridization and physical sedimentation through viscosity regulation. The collaborative design of the quaternary alloy (Ga-In-Bi-Er) breaks through the traditional liquid metal separation model that relies solely on solubility differences, providing a theoretical basis for the efficient removal of metallic impurities.

[0154] Experiment 2: Verification of ultrasonic-eddy current synergistic peeling efficiency

[0155] Experimental procedures

[0156] Sample preparation:

[0157] 5 g of each of the boron oxide solid phase samples of Examples 1-3 (ultrasound + eddy current treatment) and Comparative Example 3 (ultrasound treatment only) were taken, ultrasonically cleaned with anhydrous ethanol (40 kHz, 10 minutes) and then dried.

[0158] Surface impurity residue detection:

[0159] Field emission scanning electron microscopy (SEM, Hitachi SU8230) combined with energy dispersive spectroscopy (EDS) was used to analyze the residual area ratio of SiO2 / Al2O3 impurities on the surface of B2O3 particles (50 particles were randomly selected and the average value was calculated).

[0160] Particle dispersion test:

[0161] The sample was dispersed in deionized water (solid content 1 wt%), and the D90 value (particle size corresponding to 90% of the cumulative volume distribution) was measured using a laser particle size analyzer (Malvern Mastersizer 3000).

[0162] Eddy current field strength calibration:

[0163] The particle image velocimetry (PIV, LaVision FlowMaster) was used to measure the eddy flow shear rate (s -1 ), calculate the Reynolds number to verify the flow field state.

[0164] Data collection:

[0165] Each test was repeated 5 times, and the median was taken after excluding outliers, and the data were retained to two decimal places.

[0166] Experimental data

[0167] Table 2 Effect of ultrasonic-eddy current synergistic treatment on surface impurity residue and dispersion

[0168]

[0169] Experimental Summary

[0170] The ultrasonic cavitation effect generates a microjet impact force (pressure peak > 50 MPa) at the liquid metal-boron oxide interface, which can effectively break the surface impurity coating. However, the single ultrasonic treatment (Comparative Example 3) has low stripping efficiency due to the uneven distribution of cavitation bubbles, and the residual SiO2 / Al2O3 area accounts for as high as 8.94% and 7.25%. After the eddy flow field (Reynolds number 4500-5500) of the spiral guide plate structure is introduced, the shear rate is increased to 1080-1410s -1 The secondary flow generated by the vortex brings the uncollapsed cavitation bubbles back into the high shear area, prolonging the cavitation action time and expanding the action range.

[0171] The data of Examples 1-3 show that the synergistic effect reduces the residual area of ​​surface impurities to 2.31-4.08%, which is 60-75% less than that of Comparative Example 3. At the same time, the eddy current field has a significant effect on the dispersion of the particles after peeling, and the D90 value is reduced from 83.6 μm (Comparative Example 3) to 48.2-57.9 μm, indicating that the particle agglomeration phenomenon is effectively suppressed. The negative correlation between shear rate and residual area (R 2 =0.92) proves the synergistic mechanism of eddy current field on ultrasonic cavitation.

[0172] This experiment demonstrated the synergistic enhancement mechanism of ultrasonic cavitation and eddy current shear force: by enhancing local shear force and cavitation bubble transport, the eddy current field breaks through the energy density limitations of traditional ultrasonic treatment and addresses the problem of re-adsorption of nanoscale impurities due to van der Waals forces. This synergistic design provides a controllable physical field coupling strategy for high-precision cleaning of boron oxide surfaces.

[0173] Experiment 3: Verification of the separation effect of dynamic linkage of magnetic and electric parameters

[0174] Experimental procedures

[0175] Sample separation and processing:

[0176] Take 20 mL of each of the liquid metal phase and boron oxide solid phase mixture after treatment in Examples 1-3 (dynamic linkage of magnetoelectric parameters) and Comparative Example 4 (fixed B / U), centrifuge (8000 rpm, 10 minutes) and collect the upper liquid metal phase.

[0177] Magnetic impurity separation efficiency test:

[0178] The liquid metal phase was dissolved in nitric acid (10% v / v), and the Fe3O4 content was detected by ICP-OES (PerkinElmer Avio500). The separation efficiency was calculated as follows:

[0179] Separation efficiency (%) = (initial Fe3O4 concentration - concentration after treatment) / initial concentration × 100

[0180] Non-magnetic charged impurities detection:

[0181] Boron oxide solid phase samples were taken and the residual Al2O3 content was determined by X-ray fluorescence spectroscopy (XRF, Bruker S8TIGER) to calculate the separation efficiency.

[0182] Reunion rate test:

[0183] The surface potential of the separated boron oxide particles was measured using a Zeta potential meter (Malvern Zetasizer Nano ZS). Dynamic light scattering (DLS) was used to monitor the change in particle size and calculate the reagglomeration rate.

[0184] Reagglomeration rate (%) = (DLS test D50 value - initial D50 value) / initial D50 value × 100

[0185] Magnetoelectric parameter recording:

[0186] The magnetic field intensity (B) and pulsed high-voltage electrostatic field voltage (U) are collected in real time to verify whether they conform to the equation U = -18.75B + 3.5.

[0187] Experimental data

[0188]

[0189] Experimental Summary

[0190] Dynamic magnetoelectric parameter linkage (U = -18.75B + 3.5) achieves synchronous separation of magnetic impurities (Fe3O4) and non-magnetic charged particles (Al2O3) by regulating the spatiotemporal distribution of Lorentz force and Coulomb force. In Examples 1-3, the real-time linkage of magnetic field intensity B and voltage U makes Fe3O4 separation efficiency reach 90.1-96.3%, Al2O3 separation efficiency reach 82.3-89.7%, and particle reagglomeration rate is controlled at 3.8-7.2%. However, in Comparative Example 4 (fixed B / U), the Coulomb force and magnetic field force are unbalanced because the equation relationship is not satisfied, resulting in Fe3O4 separation efficiency dropping to 78.4%, Al2O3 efficiency only 63.9%, and reagglomeration rate surging to 24.6%.

[0191] Zeta potential analysis showed that the surface potential of the boron oxide particles in Examples 1-3 was stable at -35 to -40 mV (an absolute value >30 mV is the threshold for stable dispersion). However, in Comparative Example 4, impurity resorption caused the potential to fluctuate to -22 mV, weakening the electrostatic repulsion between particles and inducing significant agglomeration. This phenomenon confirms the mechanism by which the dynamic linkage equation suppresses impurity resorption by balancing the critical conditions of charge neutralization and particle dispersion.

[0192] Experimental data further revealed that increasing the magnetic field strength B (e.g., B = 1.05 T in Example 3) and lowering the voltage U to -15.8 kV according to the equation can avoid excessive particle polarization caused by excessive Coulomb forces. This parameter collaborative optimization mechanism breaks through the technical bottleneck of traditional single physical field separation and provides a controllable energy-field matching strategy for the efficient separation of complex impurity systems.

[0193] Experiment 4: Verification of adsorption performance of gradient porous ceramics

[0194] Experimental procedures

[0195] Sample processing:

[0196] Take 10 g of each of the boron oxide solid phase samples treated in Examples 1-3 (double-layer gradient ceramics) and Comparative Example 5 (single-layer Al2O3 ceramics), disperse them in 100 mL of deionized water, and ultrasonically vibrate (40 kHz, 5 minutes) and then let them stand for 24 hours.

[0197] Non-metal ion adsorption test:

[0198] The SO4 in the supernatant was detected by ion chromatography (ThermoScientific Dionex ICS-6000). 2- 、Cl - Concentration, calculate adsorption capacity:

[0199] Adsorption capacity (mg / g) = (initial ion concentration - concentration after treatment) × solution volume / sample mass Adsorption bed pressure drop monitoring:

[0200] During the dynamic adsorption process (gas velocity 0.8-1.2 m / s), the pressure difference between the inlet and outlet of the adsorption bed was recorded in real time by a pressure difference sensor (Omega Engineering PX409), and the average value in the stable stage was taken.

[0201] Surface functional group analysis:

[0202] The used ZrO2 ceramics were tested by X-ray photoelectron spectroscopy (XPS, ThermoScientific K-Alpha) to analyze the zirconium phosphate nanoclusters (Zr 4+ -SO4 2- Coordination) and chemical state changes of mercaptosilane (-SH group).

[0203] Data collection:

[0204] Each experiment was repeated three times, the data were rounded to one decimal place, and outliers were eliminated by Grubbs test.

[0205] Experimental data

[0206] Table 4 Adsorption efficiency and pressure drop of gradient porous ceramics on non-metallic ions

[0207]

[0208]

[0209] Experimental Summary

[0210] The double-layer structure design of gradient porous ceramics achieves targeted adsorption of non-metallic ions through the synergistic effect of pore size classification and chemical modification. In Examples 1-3, the upper layer of Al2O3 ceramics (0.5-1.0 μm pore size) intercepts micron-sized dust particles, reducing the pressure drop to 1.2-1.8 kPa, avoiding pore blockage of the lower layer of mesoporous ZrO2; the lower layer of ZrO2 ceramics (0.1-0.2 μm pore size) is blocked by the Zr phosphate nanoclusters. 4+ -SO4 2- Coordination and hydrogen bonding of -SH groups of mercaptosilane, respectively for SO4 2- and Cl - Provides specific binding sites with an adsorption capacity of 10.8-12.7 mg / g (SO4 2- ) and 6.9-8.3 mg / g(Cl - However, due to the lack of chemical modification and pore size gradient, the adsorption capacity of Comparative Example 5 (single-layer Al2O3) was less than 30% of that of Example 1, and the pressure drop increased to 4.7 kPa.

[0211] XPS analysis shows that the ZrO2 surface zirconium phosphate nanoclusters in Example 1 are 3+ / Zr 4+ The ratio increased from the initial 0.15 to 0.38, indicating that SO4 2- Through redox reaction with Zr 4+ Stable coordination is formed; at the same time, the S2p binding energy of the -SH group shifts by 0.6 eV, confirming that Cl - This bifunctional modification makes SO4 2- With Cl - The adsorption energies reached -25.3 kJ / mol and -18.7 kJ / mol (calculated values), respectively, which were significantly higher than the physical adsorption threshold (-10 kJ / mol).

[0212] During the dynamic adsorption process, the operating temperature of 180-200℃ improves the flexibility of the mercaptosilane molecular chain through thermal activation, increasing the exposure rate of the -SH group by 40% and the adsorption active site density to 3.6-4.2 groups / nm 2 The coordinated design of gradient structure and functional modification breaks through the selectivity limitations of traditional monolayer adsorbents and provides an innovative solution for the efficient separation of complex ion systems.

[0213] Experiment 5: Verification of Grain Boundary Control by Vacuum Gradient Cooling

[0214] Experimental procedures

[0215] Sample preparation:

[0216] The boron oxide crystal samples of Examples 1-3 (gradient cooling) and Comparative Example 6 (single cooling rate) were cut into 10 mm×10 mm×2 mm slices and polished to a mirror surface using a diamond suspension.

[0217] Grain boundary impurity content detection:

[0218] Time-of-flight secondary ion mass spectrometry (TOF-SIMS, IONTOFTOF.SIMS5) was used to perform depth profiling of the sample surface (sputtering rate 0.5 nm / s) and quantify the content of Na and K impurities at the grain boundaries (atomic percentage).

[0219] Grain size uniformity analysis:

[0220] The sample surface was scanned by electron backscatter diffraction (EBSD, Oxford Instruments Symmetry) (step size 0.2 μm), and the coefficient of variation of grain size (standard deviation / average value×100%) was calculated.

[0221] Cooling rate record:

[0222] A high-speed infrared thermometer (FLIRA655sc) was used to monitor the temperature changes in the melting furnace in real time to verify that the gradient cooling curve met the set parameters.

[0223] Data collection:

[0224] For each group of samples, 5 areas were randomly selected for testing, and the average value was taken after excluding the highest / lowest value, and the data was retained to two decimal places.

[0225] Experimental data

[0226] Table 5 Effect of gradient cooling on grain boundary impurities and grain uniformity

[0227]

[0228] Experimental Summary

[0229] The vacuum gradient cooling strategy significantly reduces lattice defect density by controlling the dynamics of grain boundary migration in stages. In Examples 1-3, the first stage of rapid cooling (8-10°C / min) inhibits abnormal grain growth in the high-temperature zone above 300°C, keeping the grain size variation coefficient within 12.3-17.5%. The second stage of slow cooling (2-3°C / min) allows for full relaxation of grain boundaries in the 150-300°C temperature range, reducing the segregation of Na and K impurities at grain boundaries to 0.05-0.12 at%. In Comparative Example 6 (a single cooling rate of 5°C / min), the Na / K content at the grain boundaries surges to 0.53 / 0.41 at%, due to the inability to balance the competing relationship between grain boundary migration and impurity diffusion. The grain size variation coefficient reaches 38.6%.

[0230] TOF-SIMS depth profiling revealed that the Na signal intensity at the grain boundaries of Example 1 was two orders of magnitude lower than that within the grain interior, indicating that gradient cooling effectively blocked the diffusion path of impurities along the grain boundaries. EBSD orientation imaging further confirmed that the (001) plane orientation distribution concentration of Example 1 (extreme density 6.2) was double that of Comparative Example 6 (extreme density 3.1), indicating that gradient cooling promoted preferential crystal growth and reduced the formation of random grain boundaries.

[0231] The vacuum environment reduces the oxygen partial pressure during the melting phase, suppressing the vaporization-recondensation cycle of Na / K impurities. The two-stage gradient cooling design adjusts the ratio of grain boundary energy to driving force, ensuring that the grain boundary migration rate is always lower than the impurity diffusion rate, ultimately achieving the coordinated optimization of grain boundary chemical purity and structural integrity. This technology provides a controllable thermodynamic path for the preparation of low-defect oxide crystals.

[0232] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for purifying high-purity boron oxide, characterized in that: The following steps are involved: Step 1: Mixing crude boron oxide with liquid metal alloy and dissolving metal impurities through gradient temperature control; Step 2: Ultrasonic treatment is applied to the mixed system and an eddy current field is introduced to remove impurities on the surface of the boron oxide; Step 3: Using a magnetic field and a pulsed high-voltage electrostatic field to synergistically separate the liquid metal phase and the boron oxide solid phase; Step 4: removing non-metallic ion impurities through a gradient porous ceramic adsorption bed; Step 5: vacuum melt the boron oxide and perform gradient cooling crystallization.

2. The method for purifying high-purity boron oxide according to claim 1, wherein: The liquid metal alloy in step 1 is a Ga-In-Bi-Er quaternary alloy, which comprises Ga 68-72%, In 22-26%, Bi 5-8%, and Er 0.5-1.2% by mass.

3. The method for purifying high-purity boron oxide according to claim 1, wherein: The gradient temperature control in step 1 includes: The dissolution stage temperature is 215-225°C, the stirring rate is 300-400 rpm, and the time is 45-60 minutes; During the cooling stage, the temperature is lowered to 80-85°C at a rate of 1.5-2.5°C / min.

4. The method for purifying high-purity boron oxide according to claim 2, wherein: The ultrasound parameters in step 2 are: Frequency 20-40kHz, power density 35-45W / cm 3 , pulse duty cycle 50-70%, synchronous introduction of nitrogen microbubbles, flow rate 0.4-0.6L / min.

5. The method for purifying high-purity boron oxide according to claim 1, wherein: Impurities are separated by the synergistic effect of the magnetic field and the pulsed high-voltage electrostatic field, wherein the magnetic field strength and the electrostatic field voltage are in a negatively correlated linear relationship, and the negatively correlated linear relationship is U=-18.75B+3.5, wherein B is the magnetic field strength and U is the pulsed high-voltage electrostatic field voltage.

6. The method for purifying high-purity boron oxide according to claim 2, wherein: The gradient porous ceramic adsorption bed in step 4 comprises: Upper layer of Al2O3 ceramic, pore size 0.5-1.0μm, thickness 8-12mm; The lower layer is ZrO2 ceramic with a pore size of 0.1-0.2 μm, loaded with 8-12 wt% zirconium phosphate nanoclusters, and modified with mercaptosilane, with a thickness of 18-22 mm.

7. The method for purifying high-purity boron oxide according to claim 1, wherein: The vacuum melting temperature in step 5 is 455-465°C and the vacuum degree is ≤5×10 -3 Pa, gradient cooling includes: The first stage is cooling from 465°C to 300°C at 8-10°C / min; The second stage is cooling from 300°C to 150°C at 2-3°C / min.

8. The method for purifying high-purity boron oxide according to claim 1, wherein: The pulsed high voltage electrostatic field parameters in step 3 are: Output voltage -12±3kV, frequency 8-12Hz, duty cycle 25-35%.

9. The method for purifying high-purity boron oxide according to claim 1, wherein: The operating conditions of the adsorption bed in step 4 are: The fluidizing gas velocity is 0.8-1.2 m / s, the bed temperature is 180-200°C, and the adsorption time is 20-30 minutes.

10. A device for preparing high-purity boron powder, according to the method for purifying high-purity boron oxide according to any one of claims 1 to 9, characterized in that: include: Liquid metal processing module: nitrogen-protected stirred tank, gradient temperature control system; Ultrasonic eddy current module: including pulse ultrasonic generator, spiral guide plate and microbubble injection unit; Magnetoelectric separation module: integrates Halbach magnetic array centrifuge and pulsed high-voltage electrostatic field generator; Gradient adsorption module: Contains double-layer porous ceramic filter element and fluidized bed heating system; Vacuum crystallization module: includes vacuum induction furnace, gradient cooling device and online purity detection unit.

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