Titanium scrap recovery method

Abstract

The invention relates to the technical field of metal recovery, and discloses a titanium scrap recovery method which comprises the following steps: performing crushing and primary magnetic separation on titanium scraps in a mechanical pretreatment stage; in the cleaning and rinsing stage, a chelating agent-biosurfactant-buffer system synergistic ultrasonic-spraying combined four-step cleaning process is adopted; the method comprises the following steps: carrying out water softening pretreatment on a hard water environment, and adopting a sacrificial-functional double-layer chelating system and a ternary buffer system; water is removed in the dewatering and drying stage; and in the separation and purification stage, a high-purity titanium scrap product is obtained through multi-stage magnetic separation and multiple physical separation methods. The three functions of complexing metal ions by the chelating agent, emulsifying greasy dirt by the surfactant and stabilizing the reaction environment by the buffering agent are synchronously performed, the cleaning efficiency is improved by 3-5 times compared with that of a single cleaning mode, the problems of competitive consumption of the chelating agent and poor stability of the cleaning process in a hard water environment are solved, and high-quality recycling of titanium scraps is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal recycling, more particularly, it relates to a titanium scrap recycling method. BACKGROUND

[0002] Titanium and titanium alloys are widely used in aerospace, chemical industry, medical devices and other high-end manufacturing fields due to their excellent corrosion resistance, high strength and lightweight characteristics. A large amount of titanium scrap is generated during the processing of titanium materials. These titanium scraps have important recycling value, but the cutting fluid, mineral oil, metal dust and various metal ion impurities attached to the surface seriously affect their recycling quality.

[0003] The existing titanium scrap recycling method mainly has the following technical defects: first, the traditional single cleaning method (such as pure ultrasonic cleaning or simple spray flushing) has low cleaning efficiency and cannot completely remove the complex contaminants on the surface of the titanium scrap; second, the existing cleaning method has poor removal effect on metal ion contamination, especially Fe 3 ⁺, Cu 2 ⁺, Al 3 ⁺ ions cannot be effectively removed; third, the hard water commonly used in industrial production causes a large amount of chelating agent in the cleaning agent to be consumed by calcium and magnesium ions, resulting in high cleaning cost and unstable effect; fourth, the pH value fluctuation in the cleaning process affects the activity of the cleaning agent, making it difficult to establish a standardized process specification. SUMMARY

[0004] To solve the above technical problems, the present application provides a titanium scrap recycling method, comprising the following steps: Step 1: mechanical pretreatment: The titanium scrap is crushed by a crushing device to uniform the particle size of the titanium scrap within the range of 3-15 mm, and then magnetic separation is performed to remove iron impurities; Step 2: water softening pretreatment: The raw water is subjected to softening treatment to reduce the water hardness to below 50 mg / L; Step 3: preparation of composite cleaning solution: A double-layer chelating system and a ternary buffer system are used to prepare the cleaning solution, the double-layer chelating system includes sodium citrate with a concentration of 0.5-1.0 g / L as a sacrificial chelating agent and EDTA or DTPA with a concentration of 1.0-2.0 g / L as a functional chelating agent, the ternary buffer system is prepared by sodium phosphate dibasic, sodium carbonate and triethanolamine at a mass ratio of 2:1:1, with a total concentration of 2.0-4.0 g / L, and a biological surfactant with a concentration of 0.2-0.8 g / L and a dispersant with a concentration of 0.1-0.3 g / L are also added; Step 4: ultrasonic cleaning: The pretreated titanium chips are immersed in the composite cleaning solution, and ultrasonic waves with a frequency of 20-40 kHz and a power density of 0.8-1.5 W / cm 2 are used for cleaning for 10-20 minutes; Step 5: high-pressure spray cleaning: The titanium chips are cleaned by spraying water flow with a pressure of 0.3-0.8 MPa for 5-10 minutes; Step 6: rinsing treatment: Ultrasonic rinsing and spray rinsing are performed in sequence to remove residual cleaning agents; Step 7: dehydration and drying: Three-stage dehydration and drying treatment is performed; Step 8: multi-stage sorting: Purification is performed by magnetic separation, gravity separation, color separation, X-ray separation, and laser separation to obtain high-purity titanium chip products.

[0005] Preferably, the water quality softening pretreatment adopts a chemical precipitation method, sodium carbonate and sodium hexametaphosphate are added to raw water, sodium carbonate reacts with calcium ions to form calcium carbonate precipitate, and reacts with magnesium ions under hydrolysis conditions to form magnesium hydroxide precipitate, and sodium hexametaphosphate complexes with residual calcium and magnesium ions to form a soluble complex.

[0006] Preferably, the biosurfactant is rhamnolipid or saponin surfactant, and the dispersant is sodium polyacrylate.

[0007] Preferably, the operating conditions of the ultrasonic cleaning are as follows: the temperature of the cleaning solution is 25-45°C, the mass ratio of the titanium chips to the cleaning solution is 1:3-1:5, and the liquid level of the cleaning solution is 2-5 cm higher than the surface of the titanium chips.

[0008] Preferably, the high-pressure spray cleaning adopts a multi-angle spray system, the temperature of the spray water flow is 40-60°C, the distance between the spray nozzle and the surface of the titanium chips is 10-20 cm, and multiple spray nozzles are arranged at an angle of 60°.

[0009] Preferably, the rinsing treatment includes ultrasonic rinsing for 5-8 minutes and two-stage spray rinsing for 3-5 minutes, the water conductivity for rinsing is ≤50 μS / cm, and the residual amount of cleaning agent on the surface of the final titanium chips is ≤5 mg / kg.

[0010] Preferably, the three-stage dehydration and drying includes: cold air dehydration stage, using normal temperature air with a wind speed of 15-25 m / s for blowing for 10-15 minutes; hot air dehydration stage, using hot air with a temperature of 80-120°C and a wind speed of 10-20 m / s for treatment for 20-30 minutes; and drying stage, at a temperature of 150-200°C for 30-60 minutes, and the final moisture content of the titanium chips is ≤0.1%.

[0011] Preferably: the multi-stage separation includes: secondary magnetic separation to remove ferromagnetic impurities, high specific gravity inclusion separation to remove heavy metal impurities with density greater than 6.0 g / cm 3 , oxidized scrap color separation to separate titanium oxide scraps, high-density inclusion X-ray separation to remove high-density metal impurities, and alloy grade laser separation to distinguish pure titanium scraps from titanium alloy scraps.

[0012] Preferably: the sacrificial chelating agent preferentially complexes with calcium and magnesium ions and iron and manganese ions in water, and the functional chelating agent specifically complexes with Fe 3 ⁺, Cu 2 ⁺, Al 3 ⁺ and other impurity metal ions on the surface of titanium scraps, and the effective utilization rate of the functional chelating agent reaches more than 85%.

[0013] Preferably: the final titanium scrap product has a titanium content of greater than or equal to 99.5% and an impurity content of less than or equal to 0.5%, the cleaning efficiency is increased by 3-5 times compared to traditional single cleaning methods, and the use cost of the chelating agent is saved by more than 80% compared to the unoptimized scheme.

[0014] The beneficial effects of the present application are: The cleaning efficiency is greatly improved: through the synergistic complexation of the chelating agent and the ultrasonic cavitation phenomenon, the synergistic emulsification of the biological surfactant and the spraying water flow, and the synergistic effect of the ternary buffer system in maintaining the stability of the pH value, the simultaneous functions of the chelating agent complexing metal ions, the surfactant emulsifying oil stains, and the buffer stabilizing the reaction environment are realized, so that the removal rate of metal ions on the surface of titanium scraps reaches more than 95%, the oil stain removal rate reaches more than 98%, the cleaning efficiency is increased by 3-5 times compared to traditional single cleaning methods, and a titanium scrap product with qualified surface cleanliness is obtained.

[0015] Economic advantage in hard water environment: the sacrificial-functional double-layer chelating system effectively responds to the competitive consumption of calcium and magnesium ions in hard water by functional division, so that the effective utilization rate of the functional chelating agent is increased from 40-50% in the traditional process to more than 85%, and the total consumption of the chelating agent only needs to be increased by 10-15% to achieve the cleaning effect in soft water environment, which saves more than 80% of the use cost of the chelating agent compared to the unoptimized scheme.

[0016] The process stability is significantly improved: the ternary buffer system of phosphate-organic amine-carbonate has strong water quality fluctuation resistance, so that the fluctuation coefficient of the cleaning effect is reduced from ±25% in the traditional process to ±5%, and the standardization operation of the cleaning process in the water hardness range of 50-400 mg / L is realized, providing a stable process basis for the large-scale production and application of titanium scrap recovery.

[0017] Outstanding anti-scaling performance: The addition of sodium polyacrylate dispersant keeps calcium and magnesium salt precipitates in a dispersed state with an average particle size of less than 100 nanometers, preventing the precipitates from accumulating and depositing on the surface of pipes and equipment, effectively avoiding scaling in the cleaning system, reducing equipment maintenance costs by 60%, and extending the continuous operation time of cleaning equipment from 48 hours to more than 168 hours.

[0018] Excellent environmental friendliness: By using bio-derived surfactants such as rhamnolipids and saponins to replace traditional petrochemical-derived synthetic surfactants, the biodegradability of cleaning wastewater is improved from 30 days to less than 7 days, and the chemical oxygen demand (COD) is reduced by 40%, which meets the requirements of green manufacturing and environmental protection, and provides an environmentally friendly technology path for the clean production upgrade of the titanium scrap recycling industry. Attached Figure Description

[0019] Figure 1 These are pH stability comparison curves of different buffer systems of the present invention; Figure 2 This is a bar chart comparing the process stability of different buffering systems of the present invention. Detailed Implementation

[0020] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0021] Example 1 This embodiment proposes a method for recycling titanium scrap, including the following steps: Step 1: Mechanical pretreatment: The titanium shavings are crushed using a crushing device to make the particle size uniform at 9mm, and then magnetic separation is performed to remove iron impurities. Step 2: Water softening pretreatment: The raw water is softened to reduce its hardness to below 50 mg / L; Step 3: Preparation of the composite cleaning solution: The cleaning solution is prepared by using a double-layer chelating system and a ternary buffer system, the double-layer chelating system includes 0.8 g / L of sodium citrate as a sacrificial chelating agent and 1.5 g / L of EDTA or DTPA as a functional chelating agent, the ternary buffer system is prepared by sodium phosphate dibasic, sodium carbonate and triethanolamine at a mass ratio of 2:1:1, and the total concentration is 3.0 g / L, and 0.5 g / L of a biological surfactant and 0.2 g / L of a dispersant are added at the same time; Step 4: ultrasonic cleaning: The pretreated titanium chips are immersed in the composite cleaning solution, and ultrasonic waves with a frequency of 30 kHz and a power density of 1.2 W / cm 2 are used for cleaning for 15 minutes; Step 5: high-pressure spray cleaning: The titanium chips are washed by a spray water flow with a pressure of 0.6 MPa for 8 minutes; Step 6: rinsing treatment: Ultrasonic rinsing and spray rinsing are sequentially performed to remove residual cleaning agents; Step 7: dehydration and drying: Three-stage dehydration and drying treatment is performed; Step 8: multi-stage sorting: Purification is performed by magnetic separation, gravity separation, color separation, X-ray separation and laser separation to obtain high-purity titanium chip products.

[0022] Wherein: The water quality softening pretreatment adopts a chemical precipitation method, sodium carbonate and sodium hexametaphosphate are added to raw water, calcium carbonate precipitate is generated by the reaction of sodium carbonate and calcium ions, magnesium hydroxide precipitate is generated by the reaction of sodium carbonate and magnesium ions under hydrolysis conditions, and soluble complex is formed by the complexation of sodium hexametaphosphate and residual calcium and magnesium ions.

[0023] The biological surfactant is a rhamnolipid surfactant, and the dispersant is sodium polyacrylate.

[0024] The operation conditions of ultrasonic cleaning are as follows: the temperature of the cleaning solution is 35℃, the mass ratio of titanium chips to cleaning solution is 1:4, and the liquid level of the cleaning solution is 3 cm higher than the surface of the titanium chips.

[0025] The high-pressure spray cleaning adopts a multi-angle spray system, the temperature of the spray water flow is 50℃, the distance between the nozzle and the surface of the titanium chips is 15 cm, and multiple nozzles are arranged at an angle of 60°.

[0026] The rinsing treatment includes ultrasonic rinsing for 6 minutes and two-stage spray rinsing for 7 minutes, the water conductivity for rinsing is ≤50 μS / cm, and the residual amount of cleaning agent on the surface of the final titanium chips is ≤5 mg / kg.

[0027] Three-stage dehydration drying includes: cold air dehydration stage using air blowing at room temperature for 12 minutes at a wind speed of 20 m / s; hot air dehydration stage using hot air treatment for 25 minutes at a temperature of 100 DEG C and a wind speed of 15 m / s; drying stage is treated at a temperature of 180 DEG C for 45 minutes, and the final titanium scrap moisture content is less than or equal to 0.1%.

[0028] Multi-stage sorting includes: secondary magnetic separation removes ferromagnetic impurities, high specific gravity inclusion sorting removes heavy metal impurities with a density greater than 6.0 g / cm 3 , oxidized scrap color sorting separates titanium oxide scrap, high-density inclusion X-ray sorting removes high-density metal impurities, and alloy grade laser sorting separates pure titanium scrap from titanium alloy scrap.

[0029] The sacrificial chelating agent preferentially complexes with calcium and magnesium ions and iron and manganese ions in water, and the functional chelating agent specifically complexes with impurity metal ions such as Fe 3 ⁺, Cu 2 ⁺, Al 3 ⁺ on the surface of the titanium scrap, and the effective utilization rate of the functional chelating agent is greater than 85%.

[0030] The final titanium scrap product has a titanium content of greater than or equal to 99.5% and an impurity content of less than or equal to 0.5%, the cleaning efficiency is increased by 3-5 times compared to traditional single cleaning methods, and the use cost of the chelating agent is saved by more than 80% compared to the unoptimized scheme.

[0031] Example 2 The difference between this embodiment and Example 1 is that: The titanium scrap is crushed by a crushing device to uniform the particle size of the titanium scrap to 3 mm, and then the iron impurities are removed by magnetic separation; A double-layer chelating system and a ternary buffer system are used to prepare the cleaning solution, the double-layer chelating system includes 0.5 g / L of sodium citrate as a sacrificial chelating agent and 1.0 g / L of EDTA or DTPA as a functional chelating agent, and the ternary buffer system is prepared from disodium hydrogen phosphate, sodium carbonate and triethanolamine at a mass ratio of 2:1:1, with a total concentration of 2.0 g / L, and 0.2 g / L of a biological surfactant and 0.1 g / L of a dispersant are also added; The pretreated titanium scrap is immersed in the composite cleaning solution, and ultrasonic cleaning is performed for 10 minutes using an ultrasonic wave with a frequency of 20 kHz and a power density of 0.8 W / cm 2 ; The titanium scrap is washed by a spray water flow with a pressure of 0.3 MPa for 5 minutes; The biological surfactant is a saponin surfactant, and the dispersant is sodium polyacrylate.

[0032] The operating conditions of the ultrasonic cleaning are as follows: the temperature of the cleaning solution is 25℃, the mass ratio of titanium chips to the cleaning solution is 1:3, and the cleaning solution is 2cm higher than the surface of the titanium chips.

[0033] The high-pressure spray cleaning adopts a multi-angle spray system, the temperature of the spray water flow is 40℃, the distance between the nozzle and the surface of the titanium chips is 10cm, and multiple nozzles are arranged at an angle of 60°.

[0034] The rinsing process includes ultrasonic rinsing for 5 minutes and secondary spray rinsing for 3 minutes, the conductivity of the rinsing water is ≤50μS / cm, and the residual amount of the cleaning agent on the surface of the titanium chips is ≤5mg / kg.

[0035] The three-stage dehydration drying includes: in the cold air dehydration stage, the normal temperature air with a wind speed of 15m / s is used for blowing for 10 minutes; in the hot air dehydration stage, the hot air with a temperature of 80℃ and a wind speed of 10m / s is used for treatment for 20 minutes; in the drying stage, the temperature is 150℃ for treatment for 30 minutes, and the final water content of the titanium chips is ≤0.1%.

[0036] Example 3 The difference between this example and Example 1 is that: The titanium chips are crushed by a crushing device to make the particle size of the titanium chips uniform at 15mm, and then the iron impurities are removed by magnetic separation; The cleaning solution is prepared by using a double-layer chelating system and a ternary buffer system, the double-layer chelating system includes sodium citrate with a concentration of 1.0g / L as a sacrificial chelating agent and EDTA or DTPA with a concentration of 2.0g / L as a functional chelating agent, the ternary buffer system is prepared by sodium phosphate dibasic, sodium carbonate and triethanolamine with a mass ratio of 2:1:1, and the total concentration is 4.0g / L, and a biological surfactant with a concentration of 0.8g / L and a dispersant with a concentration of 0.3g / L are added at the same time; The pretreated titanium chips are immersed in the composite cleaning solution, and the titanium chips are cleaned by using ultrasonic waves with a frequency of 40kHz and a power density of 1.5W / cm 2 for 20 minutes; The titanium chips are washed by a spray water flow with a pressure of 0.8MPa for 10 minutes; The operating conditions of the ultrasonic cleaning are as follows: the temperature of the cleaning solution is 45℃, the mass ratio of titanium chips to the cleaning solution is 1:5, and the cleaning solution is 5cm higher than the surface of the titanium chips.

[0037] The high-pressure spray cleaning adopts a multi-angle spray system, the temperature of the spray water flow is 60℃, the distance between the nozzle and the surface of the titanium chips is 20cm, and multiple nozzles are arranged at an angle of 60°.

[0038] The rinsing process includes ultrasonic rinsing for 8 minutes and secondary spray rinsing for 5 minutes, the conductivity of the rinsing water is ≤50μS / cm, and the residual amount of the cleaning agent on the surface of the titanium chips is ≤5mg / kg.

[0039] Three-stage dehydration drying includes: cold air dehydration stage using air speed 25 m / s of normal temperature air blowing 15 minutes; hot air dehydration stage using temperature 120℃, air speed 20 m / s of hot air treatment 30 minutes; drying stage at temperature 200℃ for 60 minutes, the final titanium scrap moisture content ≤0.1%.

[0040] Example 4 In this embodiment, a titanium scrap recycling method is proposed, comprising the following steps: Step one: mechanical pretreatment The titanium scrap to be treated is pretreated by mechanical crushing and magnetic separation equipment in turn: (1) tearing treatment: using double-shaft shredder (power ≥ 15 kW), blade gap adjustment to 8-12 mm, feed size ≤100 mm, processing capacity 1-3 t / h. The large titanium scrap is torn to a size convenient for subsequent crushing; (2) crushing treatment: using jaw crusher (feed inlet ≥200×300 mm), discharge outlet adjustment to 3-15 mm, crushing ratio 1:3-1:5, so that the titanium scrap size is uniform in the range of 3-15 mm, of which 3-5 mm accounts for 30-40%, 5-10 mm accounts for 40-50%, and 10-15 mm accounts for 10-20%; (3) primary magnetic separation: using dry magnetic separator (magnetic field strength 0.6-0.8 T), removing iron impurity particles with particle size greater than 1 mm, feed uniformity control in ±10%, belt speed 0.8-1.5 m / s, magnetic impurity removal rate ≥90%.

[0041] Quality control: the crushed titanium scrap should have no obvious long strip and flaky particles, aspect ratio ≤3:1, particle size distribution meets the set range, and magnetic impurity content ≤0.5%. The pretreated titanium scrap with uniform particle size and low magnetic impurity content is obtained, providing suitable material state for the subsequent cleaning process. This step is a conventional technique in the art, but the particle size control and magnetic separation impurity removal lay the foundation for the implementation of the subsequent innovative cleaning process.

[0042] Step two: water softening pretreatment Before preparing the cleaning solution, the raw water is pretreated for softening to remove calcium and magnesium ions.

[0043] Method one: ion exchange resin softening method, using 001×7 strong acid cation exchange resin, resin layer height 60-100 cm, water flow rate 8-15 m / h, when the water hardness ≤50 mg / L, stop softening; Method two: chemical precipitation softening method, adding industrial grade sodium carbonate to the raw water.

[0044] Chemical softening operation: First, the hardness of raw water is measured (EDTA titration method, GB / T 5750.4-2006), and 1.1-1.3 times of the theoretical dosage of sodium carbonate is added. The dosage calculation formula is: sodium carbonate dosage (mg / L) = 0.94 x total hardness (mg / L CaCO3).

[0045] Stirring at room temperature for 30-60 minutes, precipitate softening reaction: sodium carbonate reacts with calcium ions to form calcium carbonate precipitate; sodium carbonate reacts with magnesium ions under hydrolysis conditions to form magnesium hydroxide precipitate. After 60-120 minutes of standing and precipitation, 5-15 mg / L of sodium hexametaphosphate is added to the supernatant to form a stable soluble complex with the residual calcium and magnesium ions (residual amount ≤50 mg / L) through polydentate complexation. 2 ⁺and Mg 2 ⁺content in the treated water is measured using an atomic absorption spectrophotometer, the total hardness is calculated, and the treated water hardness is required to be ≤50 mg / L (calculated as CaCO3), the pH value is 7.5-8.5, and the turbidity is ≤5 NTU. The softened water obtained meets the requirements of subsequent cleaning solution preparation and is used to prepare a composite cleaning solution.

[0046] Step three: preparation of composite cleaning solution A double-layer chelating system and a ternary buffer system are used to prepare the cleaning solution, and the specific component specifications and addition methods are as follows: (1) Sacrificial chelating agent addition: add analytical pure sodium citrate to the softened water, and control the concentration at 0.5-1.0 g / L, preferably 0.7-0.8 g / L. Use an electromagnetic stirrer to stir at a speed of 300-500 rpm for 5-10 minutes until completely dissolved. The stability constant lgK of this chelating agent with calcium, magnesium, and iron ions is 3.2, 2.9, and 25.1, respectively, which preferentially complexes with residual Ca 2 ⁺, Mg 2 ⁺, Fe 2 ⁺, Mn 2 ⁺, and other interfering ions. (2) Functional chelating agent addition: add analytical pure ethylenediaminetetraacetic acid disodium salt or diethylenetriamine pentaacetic acid, and control the concentration at 1.0-2.0 g / L, preferably 1.3-1.7 g / L. Continue stirring for 10-15 minutes until completely dissolved. The stability constant lgK of this chelating agent with Fe 3 ⁺, Cu 2 ⁺, and Al 3 ⁺ is 25.1, 18.8, and 16.5, respectively, which specifically complexes with impurity metal ions on the surface of titanium chips. (3) Biological surfactant addition: add biosynthetic rhamnolipid (molecular formula C 26 H 48O9, molecular weight 520.66, purity ≥95%, surface tension ≤30 mN / m) or saponin surfactants (such as tea saponin, molecular formula C 57 H 90 O 26 , molecular weight 1221.33, purity ≥90%) at a concentration of 0.2-0.8 g / L, preferably at a concentration of 0.4-0.6 g / L. Stir at room temperature for 15-20 minutes until the solution is uniform and transparent, and use it to emulsify the cutting fluid and mineral oil on the surface of the titanium chips into droplets with a diameter of 1-10 microns; (4) Construction of a ternary buffer system: Add analytical grade disodium hydrogen phosphate, anhydrous sodium carbonate, and triethanolamine in sequence, with a mass ratio of 2:1:1, and a total concentration of 2.0-4.0 g / L, preferably a total concentration of 2.5-3.5 g / L. After stirring and dissolving, use a pH meter to measure and adjust the pH of the cleaning solution to be stable within the range of 7.0-8.5, preferably 7.5-8.0; (5) Add dispersant: Add sodium polyacrylate (molecular weight 5000-15000, solid content ≥90%) at a concentration of 0.1-0.3 g / L, preferably at a concentration of 0.15-0.25 g / L. Finally, stir for 5-8 minutes to prevent calcium and magnesium salt precipitates from aggregating into particles with a particle size greater than 100 nanometers.

[0047] After adding the above components in sequence and thoroughly stirring and mixing, a clear, pH-stable, double-chelate-containing, biosurfactant, ternary buffer, and dispersant composite cleaning solution is obtained, with a surface tension of 25-35 mN / m and a conductivity of 2-8 mS / cm.

[0048] Step four: ultrasonic cleaning After pretreatment, immerse the titanium chips in the prepared composite cleaning solution and use a multi-frequency ultrasonic cleaning device for cleaning. Equipment requirements: ultrasonic cleaning tank volume ≥10L, equipped with dual-frequency or triple-frequency ultrasonic transducers (20-40 kHz adjustable), total power ≥300W, power density controlled at 0.8-1.5 W / cm 2 , preferably 1.0-1.2 W / cm 2 . Operating conditions: cleaning solution temperature controlled at 25-45°C, preferably 30-40°C; mass ratio of titanium chips to cleaning solution is 1:3-1:5, preferably 1:4; the liquid level of the cleaning solution should be 2-5 cm higher than the surface of the titanium chips.

[0049] Cleaning process: After starting the ultrasonic device, the cavitation phenomenon (i.e. the formation, growth and collapse process of micro-bubbles in the liquid) generated by the ultrasonic waves in the cleaning solution produces micro-jets with a diameter of 1-5 microns and local high pressure shock waves with a pressure of 10-50 MPa on the surface of the titanium chips, which promotes the chelating agent molecules to rapidly penetrate into the micropores and cracks on the surface of the titanium chips with a depth of 1-20 microns, and to react with the metal ions such as Fe 3 ⁺, Cu 2 ⁺, Al 3 ⁺ to form stable water-soluble complexes, and the reaction equation is EDTA 4 ⁻ + Fe 3 ⁺ → [Fe-EDTA]⁻, EDTA 4 ⁻ + Cu 2 ⁺ → [Cu-EDTA] 2 ⁻, EDTA 4 ⁻ + Al 3 ⁺ → [Al-EDTA]⁻. At the same time, the acoustic streaming effect (flow rate 1-10 cm / s) and the periodic oscillation of the cavitation bubbles generated by the ultrasonic waves promote the rearrangement of the biosurfactant molecules at the oil-water interface, reducing the oil-water interfacial tension from 72 mN / m for pure water to 20-35 mN / m, and emulsifying the attached cutting fluid and mineral oil into stable droplets with a diameter of 1-10 microns. The cleaning time is controlled at 10-20 minutes, preferably 15 minutes. Intermediate product detection: sample every 5 minutes to detect the metal ion concentration (using atomic absorption spectrometry) and surface tension (using a surface tension meter) in the cleaning solution, when the Fe 3 ⁺ concentration is ≥10 mg / L and the surface tension is ≤35 mN / m, it indicates that the cleaning is sufficient. Finally, the wet titanium chips with surface-attached water-soluble metal complexes and emulsified oil droplets are obtained, the surface of the titanium chips is silver-gray luster, and there is no obvious oil stain residue.

[0050] Step five: high-pressure spray cleaning A multi-angle high-pressure spray system is used to flush and clean the wet titanium chips after ultrasonic cleaning. Equipment requirements: high-pressure cleaning machine pressure ≥ 1.0 MPa, equipped with fan-shaped nozzles (spray angle 90-120°) and straight-flow nozzles, flow rate ≥ 20 L / min; the spray tank is equipped with a screen separation device and a backflow water circulation system. Operating conditions: the spray pressure is set to 0.3-0.8 MPa, preferably 0.5-0.6 MPa; the spray water flow temperature is controlled at 40-60°C, preferably 45-55°C; the distance between the nozzles and the surface of the titanium chips is kept at 10-20 cm, preferably 12-15 cm; multiple nozzles are arranged at an angle of 60° to ensure full coverage of the titanium chip surface.

[0051] Cleaning process: First, use the fan-shaped nozzle for large area flushing for 2-3 minutes to remove loose attachments, then use the straight-flow nozzle for fine flushing of key parts for 3-5 minutes. The mechanical scouring force (shear stress 10-100 Pa) generated by the spray water flow will strip the metal complex and emulsified oil droplets loosely attached to the surface of titanium chips and carry them away, preventing the pollutants from re-depositing on the cleaned surface. During the spraying process, the water flow shear force further reduces the emulsified oil droplet size to 0.5-5 microns and stabilizes its dispersion in the wastewater, completing the complete separation of oil stains from the surface of titanium chips.

[0052] The cleaning time is controlled at 5-10 minutes, preferably 7 minutes. Intermediate product detection: Collect wastewater samples during the cleaning process, and use a turbidimeter to measure the turbidity of the wastewater. When the wastewater turbidity is ≤10 NTU, it indicates that the surface contaminants have been basically removed. Quality judgment: Visually, the surface of the titanium chips should present a uniform silver-white metallic luster, without obvious oil stain spots and color differences. Finally, clean titanium chips with a surface metal ion and oil stain removal rate of more than 95% are obtained, with a surface roughness Ra≤3.2 μm.

[0053] Step six: ultrasonic rinsing After spraying cleaning, the titanium chips are immersed in clean softened water at a temperature of 25-35°C for ultrasonic rinsing to remove chelating agents, surfactants, and buffer agents and other cleaning agent components remaining on the surface of the titanium chips. Rinsing water requirements: conductivity ≤50 μS / cm, pH value 6.5-7.5, suspended solids ≤10 mg / L. Equipment parameters: ultrasonic frequency and power density are the same as in step four (20-40 kHz, 0.8-1.5 W / cm 2 ), and the mass ratio of titanium chips to rinsing water is 1:2-1:3, preferably 1:2.5.

[0054] Rinsing operation: It is carried out in two times, the first rinsing for 3-4 minutes, and then the titanium chips are taken out and drained for 30 seconds, and then fresh rinsing water is used for the second rinsing for 2-4 minutes. The titanium chips are stirred every 2 minutes during the rinsing process to ensure uniform rinsing. The rinsing water replacement standard: when the conductivity is ≥100 μS / cm or the pH value deviates from 7.0±1.0, new water should be used.

[0055] Residual detection: Take the rinsed titanium chip sample, extract the surface residues with deionized water, and use ion chromatography to detect the chelating agent content and spectrophotometry to detect the surfactant content. The requirements are that the chelating agent residue is ≤5 mg / kg, the surfactant residue is ≤3 mg / kg, and the total residual amount is ≤10 mg / kg. Rinsed titanium chips with a clean surface and qualified cleaning agent residues are obtained.

[0056] Step seven: secondary spray rinsing The second rinsing of the titanium chips is performed using deionized water with a temperature of 25-35 °C and a conductivity of < 20 μS / cm to further remove the cleaning agent components remaining on the surface of the titanium chips. Equipment requirements: low-pressure spraying system equipped with atomizing nozzles (atomizing particle size 50-200 μm), water flow 10-15 L / min.

[0057] Operating conditions: the spraying pressure is controlled at 0.2-0.5 MPa, preferably 0.3 MPa; the distance between the nozzle and the titanium chips is 8-15 cm, preferably 10 cm; reciprocating spraying is used, covering each part of the titanium chip surface > 2 times; the spraying time is controlled at 3-5 minutes, preferably 4 minutes.

[0058] Water quality monitoring: during the spraying process, waste water is collected and the conductivity of the waste water is monitored in real time using a conductivity meter. When the conductivity of the waste water is < 30 μS / cm, it indicates that the rinsing is complete. Final detection: the total residual amount of cleaning agent on the surface of the titanium chips is < 5 mg / kg, the pH value is 6.8-7.2, and the moisture content is 15-25%. A clean and moist titanium chip with a uniform silver-white metallic luster is obtained.

[0059] Step eight: three-stage dehydration drying The moist titanium chip after cleaning and rinsing is sequentially subjected to three-stage dehydration drying treatment: (1) Cold air dehydration stage: a centrifugal fan (power > 3 kW) is used to generate normal temperature air (20-30 °C) with a wind speed of 15-25 m / s to blow the titanium chips. The titanium chip layer thickness is < 5 cm, the blowing time is 10-15 minutes, preferably 12 minutes. The free water attached to the surface of the titanium chip is removed by forced convection. The water removed in this stage accounts for about 60-70% of the total moisture content; (2) Hot air dehydration stage: a hot air circulating drying device is used, with a set temperature of 80-120 °C, preferably 90-110 °C, a wind speed of 10-20 m / s, preferably 15 m / s, and a relative humidity of < 60%. The titanium chips are evenly spread in a perforated tray with a thickness of < 3 cm, and the treatment time is 20-30 minutes, preferably 25 minutes. The combined water in the capillary pores inside the titanium chip and the micro-concave places on the surface is removed by heat convection. The water removed in this stage accounts for about 25-35% of the total moisture content; (3) Drying treatment stage: a forced circulation oven or a fluidized bed dryer is used, with a set temperature of 150-200 °C, preferably 170-180 °C, and a drying time of 30-60 minutes, preferably 45 minutes. The titanium chips are placed in a single layer to ensure uniform heating, and the residual combined water and internal deep water are removed.

[0060] Moisture content testing: Samples were taken and weighed after each stage. The weight change was measured using an electronic balance (accuracy 0.1 mg), and the moisture content was calculated using the formula: Moisture content (%) = (Wet weight - Dry weight) / Dry weight × 100%. The final requirement is that the titanium scrap has a moisture content ≤ 0.1%, with no visible water marks on the surface, and exhibits a dry, silvery-white metallic luster. Dry titanium scrap meeting storage and sorting requirements is obtained.

[0061] Step Nine: Multi-stage sorting and purification The dried titanium shavings are then purified through the following sorting process: (1) Secondary magnetic separation process: A high-intensity magnetic separator (magnetic field strength ≥ 0.8 T) is used to remove ferromagnetic impurity particles with a particle size greater than 0.5 mm. The feeding speed is controlled at 1-3 t / h, the belt speed is 0.5-1.2 m / s, and the separation efficiency is ≥ 95%. (2) High-density inclusion separation process: Heavy medium separation or shaking table separation is adopted to remove inclusions with a density greater than 6.0 g / cm³ by utilizing density differences. 3 Heavy metal impurities (titanium density is 4.5 g / cm³) 3 For heavy dielectrics, ferrosilicon powder is used, and the dielectric density is controlled at 5.5-6.0 g / cm³. 3 Sorting accuracy ≥90%; (3) Oxide scrap color sorting process: A photoelectric color sorter equipped with an RGB+near-infrared spectral detection system is used to separate silvery-white metallic titanium scraps from grayish-black titanium oxide scraps based on color differences. Light source power ≥1000 W, scanning frequency ≥2000 Hz, recognition accuracy ≥0.5 mm 2 The accuracy rate for elimination is ≥98%; (4) High-density inclusion X-ray sorting process: A dual-energy X-ray transmission sorting machine is used to remove heavy metal impurities (such as Cu, Zn, Pb, etc.) with atomic numbers greater than titanium (atomic number 22) by utilizing the difference in atomic number. The X-ray tube voltage is 80-160 kV, the current is 0.5-3 mA, the detection resolution is ≤1 mm, and the sorting accuracy is ≥95%. (5) Alloy grade laser sorting process: Laser-induced breakdown spectroscopy (LIBS) sorting equipment is used to classify pure titanium chips (Ti≥99.5%) and titanium alloy chips containing alloying elements such as vanadium and aluminum according to differences in elemental composition. Laser power ≥10 mJ, pulse frequency ≥20 Hz, detected elements include V, Al, Sn, Mo, etc., and the composition detection accuracy is ≤0.1%; (6) Manual sorting process: On a sorting table with light intensity ≥1000 lux, skilled operators remove titanium chips with abnormal shape (length-to-diameter ratio >10:1) and obvious surface defects (cracks, pits, etc.). The sorting speed is ≤50 kg / h·person. (7) Three-stage magnetic separation process: using high gradient magnetic separator (magnetic field strength > 1.5 T) to remove fine ferromagnetic impurities with particle size less than 0.5 mm, medium steel wool or steel wire mesh, processing capacity 1-5 t / h; (8) Weighing and packaging process: using a vibrating screen to separate according to different specifications (3-5 mm, 5-10 mm, 10-15 mm), then weighing with an electronic scale (accuracy < 10 g), and filling into moisture-proof woven bags, each bag weighing 25 ± 0.5 kg.

[0062] Quality detection: randomly selected samples for component analysis (using ICP-OES or XRF), titanium content > 99.5%, main impurity content: Fe < 0.2%, C < 0.08%, N < 0.03%, O < 0.15%, H < 0.012%. Obtain high-purity titanium scrap products that meet the requirements of national standard GB / T 3620.1-2016.

[0063] Experimental verification Experiment 1: Comparison of cleaning efficiency 1. Purpose of the experiment To verify the cleaning efficiency improvement effect of the chelating agent-biosurfactant-buffer system combined ultrasonic-spraying cleaning method of the application in removing metal ions and oil stains from the surface of titanium scrap compared to traditional single cleaning methods.

[0064] 2. Preparation of experimental samples Select titanium scrap produced during TC4 titanium alloy processing as test samples, control the particle size of the titanium scrap within the range of 3-15 mm according to the requirements of Example 4, select 5-10 mm specifications for testing, and the surface is attached with cutting fluid and metal ion impurities. Divide the titanium scrap into 4 groups, each group weighing 500g: Control group 1: traditional ultrasonic cleaning (only using deionized water); Control group 2: traditional spraying cleaning (only using deionized water); Control group 3: traditional chemical cleaning (using 2.0 g / L EDTA solution); Experimental group: method of the application (using composite cleaning solution).

[0065] 3. Experimental conditions Experimental environment temperature: 25±2℃, cleaning solution temperature: 35±2℃, relative humidity: 50±5%, experimental water: deionized water, conductivity < 10 μS / cm, testing equipment: atomic absorption spectrometer (AAS), infrared spectrophotometer, electronic balance (accuracy 0.1 mg).

[0066] 4. Experimental steps (1) Sample pretreatment: titanium scrap samples were degreased with acetone, washed with deionized water, dried at 120°C for 2 hours, and weighed to record the initial weight.

[0067] (2) Artificial pollution: clean titanium scrap was immersed in a mixed solution containing Fe 3 ⁺(50mg / L), Cu 2 ⁺(30mg / L), and Al 3 ⁺(20mg / L) for 30 minutes, then coated with mineral oil (about 5ml / 100g titanium scrap) to form standard pollution samples with surface metal ion contents of Fe 3 ⁺(80-120mg / kg), Cu 2 ⁺(50-80mg / kg), and Al 3 ⁺(30-50mg / kg).

[0068] (3) Cleaning treatment: Control group 1: ultrasonic cleaning (40kHz, 1.0W / cm 2 , 15 minutes); Control group 2: high-pressure spray cleaning (0.5MPa, 50°C, 10 minutes); Control group 3: 2.0g / L EDTA solution immersion for 30 minutes followed by ultrasonic cleaning for 15 minutes; Experimental group: complete cleaning process according to Example 4; (4) Detection and analysis: after cleaning, the residual amount of metal ions and oil stains on the surface of the titanium scrap was analyzed.

[0069] 5. Experimental results Table 1 Comparison of cleaning effects of different cleaning methods 6. Analysis and summary The experimental results show that the chelating agent-biosurfactant-buffer system synergistic cleaning method of the present application is significantly better than the traditional single cleaning method in terms of metal ion removal and oil stain removal. The removal rates of Fe 3 ⁺, Cu 2 ⁺, and Al 3 ⁺ are 97.3%, 95.8%, and 94.2% respectively, the oil stain removal rate is 98.1%, and the comprehensive cleaning efficiency is 96.4%, which is 3.8 to 4.7 times higher than the traditional method, verifying the high efficiency of the technical scheme. The advantages of synergistic cleaning mainly lie in the fact that the chelating agent can effectively complex metal ions, the biosurfactant can efficiently emulsify oil stains, and the buffer system ensures the stability of the cleaning process.

[0070] Experiment two: chelating agent utilization rate test in hard water environment 1. Experimental purpose To verify the effective utilization rate of the chelating agent of the sacrificial-functional double-layer chelating system of the present application under different water quality conditions with different hardness, and prove that the system can effectively solve the problem of competitive consumption of chelating agent by calcium and magnesium ions in hard water environment, and achieve significant savings in chelating agent cost.

[0071] 2. Preparation of experimental samples Preparation of simulated water samples with different hardness: Soft water: hardness ≤ 50 mg / L (as CaCO3); Medium-hard water: hardness 150 mg / L - Hard water: hardness 300 mg / L; Very hard water: hardness 500 mg / L, prepared using CaCl2·2H2O and MgSO4·7H2O, Ca 2 ⁺: Mg 2 ⁺ molar ratio of 3:2.

[0072] 3. Experimental conditions Experimental temperature: 25±1℃, pH value: 7.5±0.5 Test equipment: ion chromatograph, complexometric titration device, UV-Vis spectrophotometer Standard titanium scrap sample: 8-12mm size selected within the particle size range of 3-15mm, with Fe 3 ⁺ (20mg / kg), Cu 2 ⁺ (15mg / kg), Al 3 ⁺ (10mg / kg) on the surface.

[0073] 4. Experimental steps (1) Preparation of the control group: using the traditional single chelating agent method, prepare 2.0 g / L EDTA solution in water with different hardness.

[0074] (2) Preparation of the experimental group: prepare the double-layer chelating system cleaning solution according to Example 4, with 0.8 g / L sodium citrate and 1.5 g / L EDTA.

[0075] (3) Cleaning test: treat the standard titanium scrap sample with the cleaning solution of the control group and the experimental group for 15 minutes, respectively.

[0076] (4) Chelating agent consumption analysis: determine the change in chelating agent concentration before and after cleaning by complexometric titration method.

[0077] (5) Evaluation of cleaning effect: determine the residual amount of metal ions on the surface of the treated titanium scrap.

[0078] (6) Utilization rate calculation: effective utilization rate of chelating agent (%) = (amount of chelating agent used for complexing impurities on the surface of titanium scrap / total amount of chelating agent added) × 100% 5. Experimental results Table 2 Comparison of chelant utilization rate under different water hardness 6. Analysis and summary The experimental results confirm the significant advantages of the double-layer chelating system of the present application. Under soft water conditions, the chelant utilization rates of the two methods are similar, both around 90%. However, as the water hardness increases, the chelant utilization rate of the traditional method decreases sharply, reaching only 28.4% in extremely hard water (500 mg / L), while the method of the present application still maintains a high utilization rate of 84.8%. In hard water (300 mg / L), the chelant saving amount of the method of the present application reaches 102.1%, i.e. more than half of the chelant usage is reduced while still achieving better cleaning effect. This is mainly due to the preferential consumption of calcium and magnesium ions by the sacrificial chelant (sodium citrate), which protects the effectiveness of the functional chelant (EDTA), achieving precise utilization of chelant and significant cost savings.

[0079] Experiment three: pH stability and process stability test 1. Purpose of the experiment To verify the maintenance effect of the phosphate-organic amine-carbonate ternary buffer system of the present application on the pH stability of the cleaning process, as well as the process stability performance under different water quality conditions and operating environments, to prove that the buffer system can significantly reduce the fluctuation of cleaning effect and realize process standardization.

[0080] 2. Preparation of experimental samples Preparation of cleaning solutions with different buffer systems: Control group 1: no buffer system (only chelant and surfactant are used); Control group 2: single phosphate buffer system (Na2HPO4 / NaH2PO4); Control group 3: dual phosphate-carbonate buffer system (Na2HPO4 / Na2CO3); Experimental group: ternary buffer system (Na2HPO4 / Na2CO3 / triethanolamine, mass ratio 2:1:1, total concentration 3.0 g / L).

[0081] 3. Experimental conditions Test water quality: 5 different hardness water samples in the range of 50-400 mg / L Environmental temperature: 20-40℃ variation range Cleaning time: continuous dynamic test for 8 hours Detection equipment: online pH meter, conductivity meter, turbidimeter, spectrophotometer.

[0082] 4. Experimental steps (1) pH stability test: Prepare each group of cleaning solution in different water quality, adjust the initial pH to 7.5 - simulate the actual cleaning process, add titanium scrap sample for dynamic cleaning; Record the pH value change every 30 minutes, continuously monitor for 8 hours; (2) Anti-interference ability test: Gradually add Ca 2 ⁺, Mg 2 ⁺, Fe 3 ⁺ and other interference ions to the cleaning solution; Test the influence of different concentrations of interference ions on pH stability; (3) Cleaning effect stability test: Repeat the cleaning experiment 20 times under different temperature and water quality conditions; Statistically analyze the variation coefficient of the cleaning effect to evaluate the process stability; (4) Long-term stability test: store the cleaning solution with different buffer systems for 30 days, test the pH maintenance ability, 5. Experimental results Table 3 Comparison of pH stability and process stability of different buffer systems Figure 1 The pH stability comparison curves of different buffer systems; Figure 2 The process stability comparison column chart of different buffer systems.

[0083] 6. Analysis and summary The experimental results fully verify the excellent performance of the ternary buffer system of the application. In the 8-hour continuous cleaning process, the pH fluctuation range of the non-buffer system reaches 5.82-8.95, which seriously deviates from the optimal cleaning pH range, resulting in a cleaning effect variation coefficient as high as ±28.5%. Although the single phosphate buffer system has improved, the pH still fluctuates in the range of 6.85-8.20, and the process stability is limited. The dual buffer system further improves the stability, but still has deficiencies under strong interference conditions.

[0084] The ternary buffer system of the application performs best, with pH always stable in the narrow range of 7.42-7.61, and the cleaning effect variation coefficient is only ±4.6%, which is 6.2 times more stable than the traditional non-buffer method. The addition of triethanolamine not only enhances the buffering capacity, but also has the function of cleaning aid, realizing the dual protection of pH stability and cleaning effect, and laying a solid foundation for the standardization of titanium scrap recovery process.

[0085] The above describes the embodiments of the present application, but the embodiments are not limited to the above specific embodiments, and the above specific embodiments are only illustrative but not restrictive, and the ordinary skilled in the art can make more equivalent embodiments under the inspiration of the embodiments, which are all within the protection scope of the embodiments.

Claims

1. A titanium chip recovery method characterized by, The method comprises the following steps: Step 1: mechanical pretreatment: The titanium chips are crushed by a crushing device to make the particle size of the titanium chips uniform in the range of 3-15 mm, and then magnetic separation is performed to remove iron impurities; Step 2: water softening pretreatment: The raw water is subjected to softening treatment to reduce the water hardness to below 50 mg / L; Step 3: preparation of a composite cleaning solution: A double-layer chelating system and a ternary buffer system are used to prepare the cleaning solution, the double-layer chelating system comprises sodium citrate with a concentration of 0.5-1.0 g / L as a sacrificial chelating agent and EDTA or DTPA with a concentration of 1.0-2.0 g / L as a functional chelating agent, and the ternary buffer system is prepared from sodium phosphate dibasic, sodium carbonate and triethanolamine at a mass ratio of 2:1:1, with a total concentration of 2.0-4.0 g / L, and a biological surfactant with a concentration of 0.2-0.8 g / L and a dispersing agent with a concentration of 0.1-0.3 g / L are added at the same time; Step 4: ultrasonic cleaning: The pretreated titanium chips are immersed in the composite cleaning solution and cleaned by ultrasonic waves with a frequency of 20-40 kHz and a power density of 0.8-1.5 W / cm 2 for 10-20 minutes. Step 5: high-pressure spray cleaning: The titanium chips are washed by a spray water flow with a pressure of 0.3-0.8 MPa for 5-10 minutes; Step 6: rinsing treatment: Ultrasonic rinsing and spray rinsing are performed in sequence to remove the residual cleaning agent; Step 7: dehydration and drying: Three-stage dehydration and drying treatment is performed; Step 8: multi-stage separation: Purification is performed by magnetic separation, gravity separation, color separation, X-ray separation and laser separation to obtain a high-purity titanium chip product.

2. The titanium chip recovery method according to claim 1, characterized by, The water softening pretreatment adopts a chemical precipitation method, sodium carbonate and sodium hexametaphosphate are added to the raw water, sodium carbonate reacts with calcium ions to form calcium carbonate precipitate, and reacts with magnesium ions under hydrolysis conditions to form magnesium hydroxide precipitate, and sodium hexametaphosphate complexes with residual calcium and magnesium ions to form a soluble complex.

3. The titanium chip recovery method according to claim 1, characterized by, The biological surfactant is rhamnolipid or saponin surfactant, and the dispersing agent is polyacrylic acid sodium.

4. The titanium chip recovery method according to claim 1, characterized by, The operation conditions of the ultrasonic cleaning are as follows: the temperature of the cleaning solution is 25-45℃, the mass ratio of the titanium chips to the cleaning solution is 1:3-1:5, and the liquid level of the cleaning solution is 2-5 cm higher than the surface of the titanium chips.

5. The titanium chip recovery method according to claim 1, wherein The high-pressure spray cleaning adopts a multi-angle spray system, the temperature of the spray water flow is 40-60℃, the distance between the spray nozzle and the surface of the titanium chips is 10-20 cm, and a plurality of spray nozzles are arranged at an angle of 60°.

6. The titanium chip recovery method according to claim 1, wherein The rinsing treatment comprises ultrasonic rinsing for 5-8 minutes and two-stage spray rinsing for 3-5 minutes, the water used for rinsing has an electrical conductivity of ≤50 μS / cm, and the residual amount of the cleaning agent on the surface of the final titanium chips is ≤5 mg / kg.

7. The titanium chip recovery method according to claim 1, wherein The three-stage dehydration and drying comprises the following steps: in the cold air dehydration stage, normal temperature air with a wind speed of 15-25 m / s is used for blowing for 10-15 minutes; in the hot air dehydration stage, hot air with a temperature of 80-120℃ and a wind speed of 10-20 m / s is used for treatment for 20-30 minutes; and in the drying stage, treatment is performed at a temperature of 150-200℃ for 30-60 minutes, and the final titanium chip has a water content of ≤0.1%.

8. The titanium chip recovery method according to claim 1, wherein The multi-stage sorting includes: secondary magnetic separation to remove ferromagnetic impurities, high specific gravity inclusion separation to remove heavy metal impurities with density greater than 6.0 g / cm 3 , oxidized scrap color separation to separate titanium oxide scraps, high-density inclusion X-ray separation to remove high-density metal impurities, and alloy grade laser separation to distinguish pure titanium scraps from titanium alloy scraps.

9. The titanium chip recovery method according to claim 1, characterized by, The sacrificial chelating agent preferentially complexes with calcium and magnesium ions and iron and manganese ions in water, and the functional chelating agent specifically complexes with Fe 3 ⁺, Cu 2 ⁺, Al 3 ⁺, etc. impurity metal ions on the surface of titanium chips.

10. The titanium chip recovery method according to claim 1, characterized by, The final titanium chip product has a titanium content of ≥99.5% and an impurity content of ≤0.5%.

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