Process recovery device and method for waste nickel-plated tungsten wire cutting line

Abstract

The application discloses a kind of process recovery device and method of waste nickel-plated tungsten wire cutting line, and the process recovery method includes: under the condition of continuously filling inert gas, waste nickel-plated tungsten wire diamond cutting line is heated to 1600-2000 DEG C, nickel layer is melted, and then gas jet atomization solidification is formed into nickel powder, and then spherical nickel particles are obtained by heterogenous drum wet grinding process.The tungsten wire separated is subjected to second heat treatment, and recycled tungsten wire is obtained, and the second heat treatment includes: the separated tungsten wire is heated to 600-1000 DEG C and kept for 2h, and then cooled to 200 DEG C and kept for 2h.The application can realize simple, efficient and low-cost recovery of waste nickel-plated tungsten wire diamond cutting line.

Description

Technical Field

[0001] This invention relates to the technical field of methods for recycling nickel-plated diamond cutting wire. Background Technology

[0002] With global silicon wafer production capacity exceeding 664GW in 2022, the performance of silicon wafers directly impacts wafer quality and photovoltaic module manufacturing costs, making it one of the core technological goals for cost reduction in the photovoltaic industry. Generally, diamond cutting wires with smaller diameters, lower breakage rates, and higher breaking strength produce silicon wafers with higher yield rates and thinner wafers, resulting in lower silicon material loss during the cutting process and greater profits for silicon wafer manufacturers. Among existing diamond cutting wires, carbon steel wire diamond cutting wires are the most widely used. However, under the same conditions of diamond micron powder quality, production process, and coating thickness, tungsten wire diamond cutting wires offer advantages over mainstream carbon steel wire diamond cutting wires, including smaller wire diameters (tungsten wire and steel wire are typically 35μm and 40μm respectively), longer service life (approximately 10 times longer than carbon steel wire diamond cutting wires), lower breakage rates (tungsten wire has higher tensile strength than steel wire for the same wire diameter), and higher cost-effectiveness.

[0003] The demand for tungsten wire diamond cutting wire exceeds 30 billion meters per month. However, the waste tungsten wire is currently being used as an additive in molten steel, resulting in a waste of tungsten wire and nickel metal. Therefore, there is an urgent need for a recycling method with a high recovery rate of tungsten wire and nickel metal. Tungsten wire diamond cutting wire is generally made by uniformly bonding diamond micro-powder particles with a Mohs hardness of 10 to a tungsten wire base at a certain distribution density. In subsequent applications, the tungsten wire base moves at high speed through a diamond wire cutting machine, driving the diamond particles on its surface to move at the same speed, generating cutting power and achieving high-speed grinding of objects. The tungsten wire base is generally manufactured through several processes, including pre-plating a nickel layer on metallic tungsten wire or doped tungsten wire, applying a nickel sand layer, and fixing the nickel plating. The production cost is still relatively high. Moreover, after long-term use, the shedding of surface diamond micro-powder particles generates a large amount of waste nickel-plated tungsten wire. How to recycle this waste nickel-plated tungsten wire to reduce the application cost of tungsten wire diamond cutting wire and enable it to replace carbon wire diamond cutting wire is also a problem that needs to be solved by current technology. Summary of the Invention

[0004] The purpose of this invention is to provide a process recycling device and method for waste nickel-plated tungsten wire cutting wire. This method or device is simple and convenient to operate, has good continuity, and is pollution-free and emission-free. It can effectively separate the tungsten and nickel components in waste nickel-plated diamond cutting wire at low cost, and finally obtain spherical nickel powder and reusable tungsten wire with high added value.

[0005] The present invention first provides the following technical solution:

[0006] A process for recycling waste nickel-plated tungsten wire cutting wire includes:

[0007] (1) Under the condition of continuous inert gas filling, the waste nickel-plated tungsten wire diamond cutting wire is subjected to continuous first heat treatment to obtain the separated tungsten wire and nickel-containing molten droplets;

[0008] (2) The separated tungsten wire is subjected to a second heat treatment to obtain a high-toughness tungsten wire, i.e., recycled tungsten wire;

[0009] (3) The nickel-containing molten droplets are sprayed with an inert gas to form fine droplets, which are then rapidly solidified into metal powder to obtain nickel powder particles;

[0010] (4) The nickel powder particles are wet ball-milled through a heterogeneous roller to obtain spherical nickel particles with a diameter of 50~100μm;

[0011] The temperature of the first heat treatment is 1600~2000℃. o C; The second heat treatment includes: heating the separated tungsten wire to 600~1000℃ and holding it at that temperature for 2 hours, then cooling it down to 200℃ and holding it at that temperature for 2 hours.

[0012] The above-mentioned technical solution of the present invention fully considers the difference in melting points of metallic nickel and tungsten in the first heat treatment. Under the premise of ensuring that the two can appear in different forms during heating, metallic nickel, nickel oxide, or substances containing some diamond particles can be fully removed from the tungsten wire. At the same time, it ensures that the separated tungsten wire has good surface properties, which is conducive to recycling.

[0013] In the above-mentioned technical solution of the present invention, the second heat treatment can further improve the toughness and elastic modulus of the tungsten wire, providing a mechanical basis for the subsequent preparation of diamond wire.

[0014] The above-mentioned technical solution of the present invention is simple, convenient and continuous to operate, with no pollution or emissions, and can achieve low-cost effective separation and valuable recycling of tungsten and nickel.

[0015] According to some preferred embodiments of the present invention, the winding rate of the high-toughness tungsten wire is 0.1~1m / s.

[0016] According to some preferred embodiments of the present invention, the inert gas is selected from argon.

[0017] According to some preferred embodiments of the present invention, the inert gas filling rate is 1~20 ml / min.

[0018] According to some preferred embodiments of the present invention, the wet ball milling uses heterogeneous cemented carbide grinding balls with a ball-to-material ratio of 5:1 and a ball milling speed of 80 r / min, and Ar is used as the protective atmosphere.

[0019] The present invention further provides a process recycling apparatus for implementing the above-described process recycling method, comprising: an unwinding wheel for unwinding waste nickel-plated tungsten wire diamond cutting coils; a winding wheel for winding the recycled tungsten wire; an induction furnace for performing the first heat treatment; a heating furnace for performing the second heat treatment; an inert gas container for supplying inert gas to the induction furnace; a gas flow meter for measuring the flow rate of the inert gas entering the induction furnace; and a gas drying and oxidation device connected to the gas flow meter and the induction furnace respectively. The device includes an oxidation decomposition furnace connected to both the drying and oxidation apparatus and the induction furnace; a waste gas purification device connected to the outlet of the induction furnace; a heating element and a nickel collector for collecting molten nickel metal droplets disposed in the induction furnace; a melt nozzle for forming a millimeter-diameter liquid metal column from the collected molten nickel metal droplets; an atomizing chamber for containing the liquid metal column; an atomizing nozzle for atomizing high-pressure gas and spraying it into the atomizing chamber; a nickel powder collector for collecting nickel powder from the atomizing chamber; and a heterogeneous roller and heterogeneous cemented carbide grinding balls for wet grinding the collected nickel powder particles.

[0020] According to some preferred embodiments of the present invention, the gas drying and oxidation apparatus is filled with silica gel, sodium oxide and magnesium perchlorate.

[0021] According to some preferred embodiments of the present invention, the exhaust gas purification device contains diethylhydroxylamine.

[0022] According to some preferred embodiments of the present invention, the diameter of the melt nozzle is 0.66 mm, and / or its length-to-diameter ratio is 30, its injection rate is 2~3 m / s, and its disturbance frequency is 1200 Hz.

[0023] According to some preferred embodiments of the present invention, the induction furnace is selected from a medium-frequency induction furnace with a melting zone length of 0.5~2m.

[0024] According to some preferred embodiments of the present invention, the induction furnace is provided with a heating element, which is selected from one or more of water-cooled copper induction coils, resistance wires, or silicon carbide heating elements.

[0025] According to some preferred embodiments of the present invention, the nickel collector is selected from graphite collectors and / or corundum collectors.

[0026] According to some preferred embodiments of the present invention, in the waste nickel-plated tungsten wire diamond cutting wire, the diameter of the tungsten wire is 0.032~0.035mm, and the thickness of the nickel plating layer is 3~4µm.

[0027] Using the recycling method or recycling device of the present invention, low-cost and high-efficiency recycling of waste nickel-plated tungsten wire diamond cutting wire can be achieved. The processing is simple and continuous, with high recycling rate and efficiency. The recycled products have excellent performance and can be directly put into new applications. Attached Figure Description

[0028] Figure 1 This is a schematic flowchart of the process for recycling waste nickel-plated tungsten wire diamond cutting wire according to the present invention.

[0029] Figure 2 This is a schematic diagram of the structure of the tungsten wire recovery device in the process recovery apparatus of the present invention.

[0030] Figure 3 This is a schematic diagram of the atomizing section in the nickel recovery apparatus of the present invention.

[0031] Figure 4 This is a scanning electron microscope and energy dispersive spectroscopy (EDS) image of the diamond wire used in a specific embodiment.

[0032] Figure 5 For the reason Figure 4 The scanning electron microscope and energy dispersive spectroscopy (EDS) spectra of the nickel melt obtained by diamond wire processing of the raw material are shown.

[0033] Figure 6 For the reason Figure 4 The image shows a comparison of scanning electron microscope (SEM) images of nickel powder particles (left) and spherical nickel particles (right) obtained by diamond wire processing of the raw material. Detailed Implementation

[0034] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0035] See attached document Figure 1 In one specific embodiment, the process for recycling waste nickel-plated tungsten wire diamond cutting wire of the present invention includes:

[0036] In an inert atmosphere, waste nickel-plated tungsten wire diamond cutting wire is subjected to a first heat treatment to melt its surface nickel layer, thereby obtaining a nickel solution formed by the surface nickel layer and the tungsten wire after the nickel layer is separated.

[0037] The separated tungsten wires are subjected to a second heat treatment to reduce their brittleness and improve their toughness. The resulting tungsten wires can be directly recycled.

[0038] The collected nickel solution is atomized and solidified into particles by gas jet spraying to obtain nickel powder particles;

[0039] The obtained nickel powder particles are wet-milled using a heterogeneous roller to obtain spherical nickel particles that can be directly recycled.

[0040] The second heat treatment is preferably performed under vacuum, and the wet grinding is preferably performed using heterogeneous cemented carbide grinding balls.

[0041] Further, refer to the appendix. Figure 2-3 In one specific embodiment, the process recovery apparatus for completing the above-described process recovery method includes a tungsten wire recovery apparatus and a nickel recovery apparatus, wherein the tungsten wire recovery apparatus is as shown in the attached diagram. Figure 2 As shown, the device includes: an unwinding wheel for unwinding waste nickel-plated tungsten wire diamond-cut wire coils, a winding wheel for winding tungsten wire after nickel separation, an induction furnace for first heat treatment, a heating furnace for second heat treatment, an argon cylinder for providing an inert environment to the induction furnace, a gas flow meter for measuring the argon flow rate, a gas drying and oxidation device connected to the gas flow meter and the induction furnace respectively, an oxidation decomposition furnace for decomposing oxidizing substances connected to the gas drying and oxidation device and the induction furnace respectively, and a waste gas purification device connected to the outlet end of the induction furnace; wherein, the induction furnace is equipped with multiple sets of heating elements and a nickel collector for collecting molten nickel metal drips.

[0042] The gas drying and oxidation device is filled with silica gel, sodium oxide (Na2O), and magnesium perchlorate (Mg(ClO4)2); the waste gas purification device contains DEHA (diethylhydroxylamine) to absorb volatile organic compounds. The induction furnace is equipped with multiple sets of heating elements and a nickel collector for collecting molten nickel drippings; the heating elements can be one or more of the following: water-cooled copper induction coils, resistance wires, or silicon carbide heating elements; the nickel collector can be one or more of the following: graphite collectors (more specifically, graphite crucibles), corundum collectors (more specifically, corundum crucibles), or collectors made of other refractory materials.

[0043] See attached document Figure 3 The nickel recovery device includes: a melt nozzle that collects molten nickel to form a metal liquid column with a diameter of millimeters, an atomizing chamber that contains the metal liquid column, an atomizing nozzle that atomizes high-pressure gas and sprays it into the atomizing chamber, a nickel powder collector that collects nickel powder from the atomizing chamber, and a heterogeneous roller and heterogeneous cemented carbide grinding balls for wet grinding the collected nickel powder particles.

[0044] In the above process, as the molten metal column falls, multiple high-pressure airflows around it impact the molten metal at high speeds, pulverizing it into tiny droplets, which then rapidly solidify into metal powder. The powder is collected in the form of a slurry. Due to the excessively rapid cooling rate during this process, the resulting powder has a wide shape and particle size distribution, poor sphericity, high oxygen content, and high irregularity. After further wet milling, spherical nickel particles with good sphericity, low oxygen content, and uniform shape and particle size distribution can be obtained.

[0045] Preferably, the induction furnace is a medium-frequency induction furnace with a heating temperature of 1600~2000℃ and a melting zone length of 0.5~2m.

[0046] This preferred embodiment can fully ensure that the nickel or nickel oxide on the waste nickel-plated tungsten wire diamond cutting line in the induction furnace melts, while the tungsten wire remains in a stable solid state, thus achieving effective separation of tungsten and nickel.

[0047] Preferably, the winding speed of the winding wheel is 0.1~1m / s.

[0048] Preferably, the argon gas filling rate is controlled by a gas flow meter to be 1~20 ml / min.

[0049] Preferably, the heating furnace is selected to be capable of heating to 600~1000℃ and maintaining that temperature for 2 hours, then cooling to 200℃ and maintaining that temperature for 2 hours, and then naturally cooling down.

[0050] Preferably, the diameter of the nozzle used to spray the nickel melt and the diameter of the resulting spray droplets are linearly related as y = 1.37x + 19, where x represents the nozzle diameter and y represents the spray droplet diameter.

[0051] Preferably, the nozzle has a diameter of 0.66 mm and / or an aspect ratio of 30, a jetting rate of 2-3 m / s, and a disturbance frequency of 1200 Hz. When using a nozzle with this aspect ratio for droplet jet additive manufacturing, the droplets formed can quickly become spherical, and the spherical formation distance is minimized.

[0052] In some specific embodiments, the raw material used in this invention, waste tungsten-nickel diamond cutting wire, is as shown in the attached figure. Figure 4 As shown, the raw material diamond wire is plated with a layer of nickel and inlaid with stainless steel. After the first heat treatment, the resulting nickel melt is shown in the attached figure. Figure 5 As shown, the nickel melt has high purity and exhibits a liquid phase distribution. A comparison is shown below between nickel powder particles obtained through gas jet atomization and spherical nickel particles obtained through wet milling. Figure 6 As shown, the nickel particles after wet grinding have a more regular shape and a more uniform distribution.

[0053] The technical solution of the present invention will be further demonstrated below with reference to the embodiments:

[0054] The following embodiments all use the above-mentioned recycling device, and the diameter of the tungsten wire of the waste nickel-plated tungsten diamond cutting wire is 0.034 mm, and the outer nickel plating layer is 3.5 µm.

[0055] Example 1

[0056] Take 10m of waste tungsten-nickel diamond cutting wire, place it on an unwinding wheel, pass it through an induction furnace, and then place it on a winding wheel. During this process, a vacuum pump is used to evacuate the induction furnace, and argon gas is introduced at a rate of 1ml / min. Then, the electric heating switch of the induction furnace is turned on, and the temperature is raised to 1800℃ after 20 minutes. Then, the winding wheel is started, allowing the waste tungsten-nickel diamond cutting wire to pass through the induction furnace at a speed of 0.1m / s. In the induction furnace, the nickel melts and falls onto a graphite collector. After being sprayed with argon gas at a speed of 2m / s, it cools and solidifies. The roller wet grinding speed is 150r / min, and after 3 hours, nickel powder with an average particle size of 80μm is obtained. After the waste tungsten-nickel diamond cutting wire is denicked in the induction furnace, it enters the heating furnace and is held at 800℃ for 2 hours to remove stress. Then, it is cooled to 200℃ and held for 2 hours until it cools down, and then wound up.

[0057] According to the test, the recovery rate of nickel in this embodiment is 80.23% and the recovery rate of tungsten is 88.91% (recovery rate = (theoretical total mass of nickel before implementation - total mass of nickel powder obtained after implementation) / theoretical total mass of nickel before implementation).

[0058] Example 2

[0059] Take 10m of waste tungsten-nickel-diamond cutting wire, place it on an unwinding wheel, pass it through an induction furnace, and then place it on a winding wheel. After evacuating the induction furnace using a vacuum pump, introduce argon gas at a rate of 5ml / min, turn on the electric heating switch of the induction furnace, and heat it to 1900℃ after 25min. Then start the winding wheel to allow the waste tungsten-nickel-diamond cutting wire to pass through the induction furnace at a speed of 0.3m / s. In the induction furnace, the nickel melts and falls onto a graphite collector. After being sprayed with argon gas at a speed of 2.5m / s, it cools and solidifies. The roller wet grinding speed is 270r / min, and after 6 hours, nickel powder with an average particle size of 50μm is obtained. After the waste tungsten-nickel-diamond cutting wire is denicked in the induction furnace, it enters the heating furnace and is held at 900℃ for 1.5h to remove stress. Then it is cooled to 200℃ and held for 2h until it cools down, and then wound up.

[0060] In this embodiment, the recovery rate of nickel was 82.57% and the recovery rate of tungsten was 87.13%.

[0061] Example 3

[0062] Take 10m of waste tungsten-nickel-diamond cutting wire, place it in an unwinding wheel, pass it through an induction furnace, and then place it in a winding wheel. After evacuating the induction furnace using a vacuum pump, introduce argon gas at a rate of 2.5ml / min, turn on the electric heating switch of the induction furnace, and heat it to 2000℃ after 30 minutes. Then start the winding wheel to allow the waste tungsten-nickel-diamond cutting wire to pass through the induction furnace at a speed of 0.6m / s. In the induction furnace, the nickel melts and falls onto a graphite collector. After being sprayed with argon gas at a speed of 3m / s, it cools and solidifies. The roller wet grinding speed is 80r / min, and after 3 hours, nickel powder with an average particle size of 100μm is obtained. After the waste tungsten-nickel-diamond cutting wire is denicked in the induction furnace, it enters the heating furnace and is held at 700℃ for 2 hours to remove stress. Then it is cooled to 200℃ and held for 2 hours until it cools down, and then wound up.

[0063] According to the test results, in this embodiment, the recovery rate of nickel was 84.43% and the recovery rate of tungsten was 86.69%.

[0064] The energy dispersive spectroscopy (EDS) analysis results of the waste tungsten-nickel diamond cutting wire, i.e., the raw material cutting wire, used in the above embodiments are shown in Table 1 below:

[0065] Table 1

[0066] element number of atoms Normalized mass fraction Atomic fraction O 8 7.76% 23.59% Ni 28 92.24% 76.41%

[0067] The energy dispersive spectroscopy (EDS) analysis results of the nickel particles recovered in Example 1 are shown in Table 2 below:

[0068] element number of atoms Normalized mass fraction Atomic fraction O 8 3.25% 9.86% Ni 28 96.75% 90.14%

[0069] It can be seen that the nickel powder recovery rate obtained by this method is relatively stable. Increasing the temperature of the first heat treatment will increase the recovery rate to a limited extent. The gas jet flow rate should not be too fast or too slow, and it is best to control it at 2~3 m / s. Meanwhile, heterogeneous ball milling can effectively reduce the particle size, and wet milling under argon protection can effectively prevent metal oxidation.

[0070] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A process for recycling waste nickel-plated tungsten wire cutting wire, characterized in that: include: (1) Under the condition of continuous inert gas filling, the waste nickel-plated tungsten wire diamond cutting wire is subjected to continuous first heat treatment to obtain the separated tungsten wire and nickel-containing molten droplets; (2) The separated tungsten wire is subjected to a second heat treatment to obtain a high-toughness tungsten wire, i.e., recycled tungsten wire; (3) The nickel-containing molten droplets are sprayed with an inert gas to form fine droplets, which are then rapidly solidified into metal powder to obtain nickel powder particles; (4) The nickel powder particles are wet ball-milled through a heterogeneous roller to obtain spherical nickel particles with a diameter of 50~100μm; The temperature of the first heat treatment is 1600~2000℃. o C; The second heat treatment includes: heating the separated tungsten wire to 600~1000℃ and holding it at that temperature for 2 hours, then cooling it down to 200℃ and holding it at that temperature for 2 hours.

2. The process recovery method according to claim 1, characterized in that: The winding rate of the high-toughness tungsten wire is 0.1~1m / s.

3. The process recovery method according to claim 1, characterized in that: The inert gas is selected from argon.

4. The process recovery method according to claim 1, characterized in that: The inert gas is introduced at a flow rate of 1~20 ml / min.

5. The process recovery method according to claim 1, characterized in that: The wet ball milling process uses heterogeneous cemented carbide grinding balls with a ball-to-material ratio of 5:1 and a milling speed of 80 r / min, with Ar as the protective atmosphere.

6. A process recovery apparatus for implementing the process recovery method according to any one of claims 1 to 5, comprising: Unwinding wheel used to unwind waste nickel-plated tungsten wire diamond cutting coils; A winding wheel for winding up the recycled tungsten wire; An induction furnace for performing the first heat treatment; a heating furnace for performing the second heat treatment; an inert gas container for supplying inert gas to the induction furnace; a gas flow meter for measuring the flow rate of the inert gas entering the induction furnace; a gas drying and oxidation device connected to the gas flow meter; an oxidation decomposition furnace with its two ends connected to the gas drying and oxidation device and the induction furnace respectively; a waste gas purification device connected to the outlet end of the induction furnace; a heating element disposed in the induction furnace and a nickel collector for collecting molten nickel metal droplets; a melt nozzle for forming a millimeter-diameter metal liquid column from the collected molten nickel metal droplets; an atomizing chamber for containing the metal liquid column; an atomizing nozzle for atomizing high-pressure gas and spraying it into the atomizing chamber; a nickel powder collector for collecting nickel powder from the atomizing chamber; and a heterogeneous roller and heterogeneous cemented carbide grinding balls for wet grinding the collected nickel powder particles.

7. The process recovery device according to claim 6, characterized in that, in, The gas drying and oxidation device is filled with silica gel, sodium oxide and magnesium perchlorate; and / or, the waste gas purification device contains diethylhydroxylamine.

8. The process recovery device according to claim 6, characterized in that, The diameter of the melt nozzle is 0.66 mm, and / or its length-to-diameter ratio is 30, its injection rate is 2~3 m / s, and its disturbance frequency is 1200 Hz.

9. The process recovery device according to claim 6, characterized in that, The induction furnace is selected from medium-frequency induction furnaces with a melting zone length of 0.5~2m.

10. The process recovery method according to any one of claims 1 to 5, characterized in that, In the waste nickel-plated tungsten wire diamond cutting wire, the diameter of the tungsten wire is 0.032~0.035mm, and the thickness of the nickel plating layer is 3~4µm.

11. The process recovery apparatus according to any one of claims 6 to 9, characterized in that, In the waste nickel-plated tungsten wire diamond cutting wire, the diameter of the tungsten wire is 0.032~0.035mm, and the thickness of the nickel plating layer is 3~4µm.

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