Waste hard alloy recycling method

Abstract

The invention provides a waste hard alloy recycling method which comprises the following steps: crushing a waste hard alloy by using a crusher, activating crushed fine particles by using laser heat treatment to enable the fine particles to contain an eta phase, refining the particles subjected to laser heat treatment by using an airflow mill, and carrying out plasma spheroidizing on the refined particles to obtain the waste hard alloy. And spherical hard alloy powder is obtained. The spherical hard alloy powder prepared through the method is good in performance, can replace spray granulation hard alloy powder and is widely applied to the fields of surfacing, plasma spraying, supersonic spraying, particle shot blasting and the like. According to the waste hard alloy recycling method, the recycling efficiency is high, energy consumption and pollution to the environment can be reduced, the waste hard alloy powder which is only suitable for traditional powder metallurgy originally meets the complex requirements of the emerging powder metallurgy field such as additive manufacturing, and efficient recycling of the waste hard alloy is achieved.

Description

Technical Field

[0001] This invention relates to the field of renewable resource recycling technology, and specifically to a method for recycling waste cemented carbide. Background Technology

[0002] Cemented carbide is an indispensable material in modern advanced manufacturing, widely used as a coating material for cutting tools, drills, and wear-resistant parts. It plays a very broad role in military, aerospace, machining, metallurgy, oil drilling, mining tools, electronics and communications, and construction. With economic development, global demand for cemented carbide continues to increase, leading to a large accumulation of cemented carbide waste, especially waste generated during the production of cemented carbide tools. Currently, global tungsten and cobalt resources are dwindling, particularly in my country where mineral reserves are declining, making the recycling and utilization of cemented carbide waste increasingly important.

[0003] Due to its high hardness and density, cemented carbide is difficult to dissolve by common inorganic acids and alkalis. Current recycling processes for cemented carbide mainly include high-temperature treatment, mechanical crushing, chemical treatment, and electrochemical methods. However, each of these methods has its drawbacks, such as limited applicability, environmental pollution, and the introduction of impurities. Furthermore, the recycled cemented carbide powder is not suitable for emerging powder metallurgy production processes such as additive manufacturing. Overcoming these shortcomings and defects requires technological breakthroughs and further in-depth research.

[0004] Therefore, it is necessary to use a new process to solve the above problems. Summary of the Invention

[0005] This invention provides a method for recycling waste cemented carbide. This process has the advantages of high recycling efficiency and the ability of the recycled powder to adapt to emerging powder metallurgy production processes such as additive manufacturing.

[0006] The technical solution of the present invention is as follows:

[0007] Step S1: Crush the waste cemented carbide using a crusher;

[0008] Step S2: The broken fine particles are activated by laser heat treatment to make the fine particles contain the η phase;

[0009] Step S3: The fine particles obtained after laser heat treatment in step S2 are refined by air jet milling.

[0010] Step S4: The powder refined by air jet milling in step S3 is subjected to plasma spheroidization to obtain spherical cemented carbide powder.

[0011] Furthermore, the cemented carbide waste is at least one of the following: waste generated during the tungsten powder production process, waste generated during the WC powder production process, waste generated during the cemented carbide production and processing process, and waste cemented carbide products;

[0012] Furthermore, in step S1, the output particle size of the crusher is D50 = 45 μm.

[0013] Further, in step S2, the laser used for laser heat treatment is a continuous laser with a wavelength of 900–1200 nm, a power of 100–600 W, and a scanning rate of 300–1000 mm / s. After laser heat treatment, the η-phase content of the particles is not less than 0.3 vol.%. Specifically, the laser wavelength used can be 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, or 1200 nm, or other values ​​within this range. The power factor can be 100W, 150W, 200W, 250W, 300W, 350W, 400W, 450W, 500W, 550W, or 600W, or other values ​​within this range; the scanning speed can be 300mm / s, 400mm / s, 500mm / s, 600mm / s, 700mm / s, 800mm / s, 900mm / s, or 1000mm / s, or other values ​​within this range.

[0014] Furthermore, in step S3, the gas flow rate of the air jet mill is not less than 10 m / s, and the particle size of the powder after treatment is 10-50 μm; specifically, the average particle size of the powder after treatment can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, or other values ​​within this range.

[0015] Further, in step S3, plasma spheroidization is performed using radio frequency inductively coupled plasma spheroidization. During spheroidization, the voltage is 8–11 kV, the current is 8–10 A, the carrier gas flow rate is 1–5 L / min, the center gas flow rate is 1–20 L / min, the side gas flow rate is 10–200 L / min, the argon-hydrogen ratio of the carrier gas, side gas, and center gas is 1:1–200:1, the powder feeding rate is 20–50 g / min, and the cavity pressure is 50–100 kPa. Specifically, the voltage during spheroidization can be 8 kV, 8.5 kV, or... 9kV, 9.5kV, 10kV, 10.5kV, or 11kV, or other values ​​within this range; current of 8A, 8.5A, 9A, 9.5A, or 10A, or other values ​​within this range; carrier gas velocity of 1L / min, 1.5L / min, 2L / min, 2.5L / min, 3L / min, 3.5L / min, 4L / min, 4.5L / min, or 5L / min, or other values ​​within this range; center gas velocity of 1L / The flow rates are 10 L / min, 2 L / min, 4 L / min, 6 L / min, 8 L / min, 10 L / min, 12 L / min, 14 L / min, 16 L / min, 18 L / min, or 20 L / min, or other values ​​within this range; the side airflow rate can be 10 L / min, 20 L / min, 40 L / min, 60 L / min, 80 L / min, 100 L / min, 120 L / min, 140 L / min, 160 L / min, 18 L / min, 18 L / min, 2 L / min, 40 L / min, 60 L / min, 80 L / min, 100 L / min, 120 L / min, 140 L / min, 160 L / min, 18 ... 0 L / min or 200 L / min, or other values ​​within this range; the atmosphere of the carrier gas, side gas, and center gas is argon; the powder feeding rate can be 20 g / min, 25 g / min, 30 g / min, 35 g / min, 40 g / min, 45 g / min, or 50 g / min, or other values ​​within this range; the cavity pressure can be 50 kPa, 60 kPa, 70 kPa, 80 kPa, 90 kPa, or 100 kPa, or other values ​​within this range.

[0016] Furthermore, the composition and content of the spheroidized cemented carbide powder are as follows: nitrogen content not exceeding 0.06 wt.%, oxygen content not exceeding 0.06 wt.%, silicon content not exceeding 0.1 wt.%, total amount of other impurities not exceeding 0.6 wt.%, particle size of 10-50 μm, flowability not exceeding 12 s / 50 g, and loose packing density not less than 6 g / cm3.

[0017] Compared with existing technologies, the present invention provides a method for recycling waste cemented carbide, which has the following advantages:

[0018] This invention provides a method for recycling waste cemented carbide. The waste cemented carbide is crushed and then subjected to laser heat treatment. The laser-heat-treated waste cemented carbide powder is then pulverized using an air jet mill, and finally, the pulverized waste cemented carbide powder is plasma-spheroidized. Crushing and laser heat treatment reduce the loss of the cemented carbide binder phase, making the waste cemented carbide easier to pulverize, significantly reducing environmental pollution during production, and lowering energy consumption. Plasma spheroidization improves the overall performance of the waste cemented carbide powder, expanding the applicability of the recycled cemented carbide powder, making it suitable for the complex requirements of emerging powder metallurgy fields such as additive manufacturing, whereas it was originally only applicable to traditional powder metallurgy. Attached Figure Description

[0019] Figure 1 The scanning electron microscope morphology of the recovered spherical cemented carbide powder prepared according to the present invention. Detailed Implementation

[0020] The technical solutions described below will be clearly and completely explained in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] Example 1

[0023] The main objective of this invention is to propose a method for recycling waste cemented carbide, comprising the following steps:

[0024] S1. The recovered WC-12Co cemented carbide is crushed using a crusher to obtain WC-12Co particles with a particle size of D50 = 45μm;

[0025] S2. The fine particles after crushing are activated by laser heat treatment to make the fine particles contain the η phase. The laser used for laser heat treatment is a continuous laser with a wavelength of 1060nm, a power of 350W, and a scanning rate of 400mm / s.

[0026] S3. The fine particles obtained after laser heat treatment in step S2 are refined by air jet milling. The gas flow rate of the air jet mill is 100m / s, and the average particle size of the powder after treatment is 10-50μm.

[0027] S4. The powder obtained in step S3 is subjected to plasma spheroidization to obtain spherical cemented carbide powder. During spheroidization, the voltage is 11kV, the current is 10A, the carrier gas flow rate is 5L / min, the center gas flow rate is 20L / min, the side gas flow rate is 200L / min, the atmosphere of the carrier gas, side gas and center gas is argon, the powder feeding rate is 50g / min, and the cavity pressure is 100kPa.

[0028] The spheroidized WC-12Co cemented carbide powder has a flowability of 11.3 s / 50 g and a loose packing density of 10.24 g / cm3.

[0029] Example 2

[0030] The main objective of this invention is to propose a method for recycling waste cemented carbide, comprising the following steps:

[0031] S1. The recovered WC-5TiC-10Co cemented carbide is crushed using a crusher to obtain WC-5TiC-10Co particles with a particle size of D50 = 45μm;

[0032] S2. The fine particles after crushing are activated by laser heat treatment to make the fine particles contain the η phase. The laser used for laser heat treatment is a continuous laser with a wavelength of 980nm, a power of 300W, and a scanning rate of 350mm / s.

[0033] S3. The fine particles obtained after laser heat treatment in step S2 are refined by air jet milling. The gas flow rate of the air jet mill is 90 m / s. The average particle size of the powder after treatment is 10-50 μm.

[0034] S4. The powder obtained in step S3 is subjected to plasma spheroidization to obtain spherical cemented carbide powder. During spheroidization, the voltage is 11kV, the current is 10A, the carrier gas flow rate is 5L / min, the center gas flow rate is 20L / min, the side gas flow rate is 180L / min, the atmosphere of the carrier gas, side gas and center gas is argon, the powder feeding rate is 80g / min, and the cavity pressure is 100kPa.

[0035] The spheroidized WC-5TiC-10Co cemented carbide powder has a flowability of 11.4 s / 50 g and a loose packing density of 10.38 g / cm3.

[0036] Example 3

[0037] The main objective of this invention is to propose a method for recycling waste cemented carbide, comprising the following steps:

[0038] S1. The recovered WC-6TiC-4(Ta,Nb)C-6Co cemented carbide was crushed using a crusher to obtain WC-6TiC-4(Ta,Nb)C-6Co particles with a particle size of D50 = 45μm.

[0039] S2. The fine particles after crushing are activated by laser heat treatment to make the fine particles contain the η phase. The laser used for laser heat treatment is a continuous laser with a wavelength of 1000nm, a power of 300W, and a scanning rate of 380mm / s.

[0040] S3. The fine particles obtained after laser heat treatment in step S2 are refined by air jet milling. The gas flow rate of the air jet mill is 150 m / s. The average particle size of the powder after treatment is 10-50 μm.

[0041] S4. The powder obtained in step S3 is subjected to plasma spheroidization to obtain spherical cemented carbide powder. During spheroidization, the voltage is 11kV, the current is 10A, the carrier gas flow rate is 5L / min, the center gas flow rate is 20L / min, the side gas flow rate is 200L / min, the atmosphere of the carrier gas, side gas and center gas is argon, the powder feeding rate is 100g / min, and the cavity pressure is 100kPa.

[0042] The spheroidized WC-6TiC-4(Ta,Nb)C-6Co cemented carbide powder has a flowability of 11.83 s / 50 g and a loose packing density of 9.98 g / cm3.

[0043] Comparative Example 1

[0044] Referring to Example 1, with other conditions unchanged, the powder feeding rate in Example 1 was changed to 100 g / min. The final spheroidized cemented carbide powder had a flowability of 14.7 s / 50 g and a loose packing density of 8.32 g / cm3.

[0045] Comparative Example 2

[0046] Referring to Example 2, with other conditions unchanged, the carrier gas flow rate in Example 2 was changed to 10L / min. The final spheroidized cemented carbide powder had a flowability of 15.68s / 50g and a loose packing density of 8.65g / cm3.

[0047] Comparative Example

[0048] Referring to Example 3, with other conditions unchanged, the side gas flow rate in Example 2 was changed to 300 L / min. The final spheroidized cemented carbide powder had a flowability of 14.98 s / 50 g and a loose packing density of 8.33 g / cm3.

[0049] As can be seen from the flowability and loose packing density of the cemented carbide powder after final spheroidization in Examples 1-3 and Comparative Examples 1-3, appropriately increasing the carrier gas flow rate and edge gas flow rate during spheroidization and reducing the powder feeding rate can significantly improve the flowability and loose packing density of the cemented carbide powder after final spheroidization. Under the conditions of higher carrier gas flow rate and edge gas flow rate and lower powder feeding rate, cemented carbide can absorb more appropriate heat, reduce the volatilization of binder phase elements, and thus improve the comprehensive performance of the cemented carbide powder after spheroidization.

[0050] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for recycling waste cemented carbide, characterized in that, Includes the following steps: Step S1: Crush the waste cemented carbide using a crusher; Step S2: The broken fine particles are activated by laser heat treatment to make the fine particles contain the η phase; Step S3: The fine particles obtained after laser heat treatment in step S2 are refined by air jet milling. Step S4: The powder refined by air jet milling in step S3 is subjected to plasma spheroidization to obtain spherical cemented carbide powder.

2. The method for recycling waste cemented carbide according to claim 1, characterized in that, Hard alloy waste refers to at least one of the following: waste generated during the tungsten powder production process, waste generated during the WC powder production process, waste generated during the production and processing of hard alloys, and waste hard alloy products.

3. The method for recycling waste cemented carbide according to claim 1, characterized in that, In step S1, the crusher is a hammer crusher, a cone crusher, or a compound crusher, and the output particle size is D50 = 45 μm.

4. The method for recycling waste cemented carbide according to claim 1, characterized in that, In step S2, the laser used for laser heat treatment is a continuous laser with a wavelength of 900–1200 nm, a power of 100–600 W, and a scanning rate of 300–1000 mm / s. After laser heat treatment, the η phase content of the particles is not less than 0.3 vol.%.

5. The method for recycling waste cemented carbide according to claim 1, characterized in that, In step S3, the gas flow rate of the air jet mill is not less than 10 m / s, and the particle size of the powder after treatment is 10-50 μm.

6. The method for recycling waste cemented carbide according to claim 1, characterized in that, In step S3, plasma spheroidization is radio frequency inductively coupled plasma spheroidization. During spheroidization, the voltage is 8-11 kV, the current is 8-10 A, the carrier gas flow rate is 1-5 L / min, the center gas flow rate is 1-20 L / min, the side gas flow rate is 10-200 L / min, the atmosphere of the carrier gas, side gas and center gas is argon, the powder feeding rate is 20-50 g / min, and the cavity pressure is 50-100 kPa.

7. The method for recycling waste cemented carbide according to claim 1, characterized in that, The composition and content of the spheroidized cemented carbide powder are as follows: nitrogen content not exceeding 0.06 wt.%, oxygen content not exceeding 0.06 wt.%, silicon content not exceeding 0.1 wt.%, total amount of other impurities not exceeding 0.6 wt.%, particle size of 10-50 μm, flowability not exceeding 12 s / 50 g, and loose packing density not less than 6 g / cm3.

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