Recycled grinding material and recycling method thereof

Abstract

The invention provides a recycled abrasive material and a recycling method thereof, the recycled abrasive material comprises alkane organic matters, and the contact angle of the recycled abrasive material is not higher than 55 degrees. The recycled grinding material can be uniformly dispersed in the oily cutting fluid, so that the cutting effect is improved.

Description

Technical Field

[0001] The invention relates to the field of high-hardness abrasive recovery, and in particular to a recovered abrasive and a recovery method thereof. Background Art

[0002] In recent years, high-performance materials with high breakdown field strength, high saturated electron drift rate, high thermal conductivity, and good chemical stability have gradually been developed and applied, such as single crystal materials such as silicon carbide, silicon, and sapphire. Since these materials have extremely high hardness and require high processing precision, their cutting process is usually to mix a specific proportion of high-hardness abrasives (diamond, silicon carbide, etc.) with cutting fluid to form a slurry. Under the high-speed movement of the steel wire, the abrasive attached to the steel wire repeatedly rubs the high-performance material, thereby achieving the cutting of high-performance materials. However, during the cutting process, the debris of the high-performance material cut off is brought into the cutting slurry. As the proportion of debris in the cutting slurry increases, the cutting ability of the cutting slurry decreases, and it is generally discarded directly after reaching a certain lifespan. The cutting waste slurry contains a large amount of abrasives, and it is of certain significance to recover the abrasives in the cutting waste slurry.

[0003] Regarding slurries composed of oily cutting fluids and abrasives (e.g., slurries for cutting silicon carbide wafers), the recovery of abrasives from such mortars is difficult due to the high viscosity of such mortars and the complex composition of the waste slurry after cutting, which contains not only base oil and a variety of organic additives, but also impurities such as debris from high-performance materials and metal debris generated during the cutting process. Currently, the methods for recovering abrasives from such mortars mainly include: first obtaining a solid slurry through mechanical separation, then using various organic solvents to remove the oily substances in the slurry, then using concentrated acid at high temperature to remove metal impurities, and finally removing the debris from the high-performance material by filtration or centrifugation to obtain the recovered abrasive, such as the processes disclosed in CN116160569A and CN112978728A. Although the abrasive recovery rate in this method is high, the purity of the abrasive is low, and the excessive residual organic components will cause the abrasive to agglomerate, which is not conducive to the dispersion of the recovered abrasive in the oily cutting fluid, thereby affecting the cutting effect. In addition, the use of concentrated acid in the impurity removal process is not only unfriendly to the environment, but also increases safety hazards and increases the recovery cost. Summary of the Invention

[0004] The present invention provides a recycled abrasive and a recycling method thereof, which can effectively improve the purity of the recycled abrasive, and the recycled abrasive can be evenly dispersed in an oily cutting fluid, thereby improving the cutting effect.

[0005] In one aspect of the present invention, a recycled abrasive is provided, wherein the recycled abrasive includes alkane organic matter, and the contact angle of the recycled abrasive is not higher than 55°.

[0006] According to one embodiment of the present invention, the mass percentage of the alkane organic matter in the recycled abrasive is less than or equal to 6%;

[0007] Preferably, the mass percentage of the alkane organic matter in the abrasive is less than or equal to 3%.

[0008] According to one embodiment of the present invention, the contact angle of the recycled abrasive is 25° to 55°, preferably 30° to 55°.

[0009] According to one embodiment of the present invention, the angle of repose of the recycled abrasive is greater than 40° and less than or equal to 60°. Preferably, the angle of repose of the recycled abrasive is greater than 40° and less than or equal to 50°.

[0010] and / or, the particle size D50 of the recycled abrasive is 6 to 8 μm, preferably 6.5 to 7.5 μm;

[0011] and / or, the sphericity of the recycled abrasive is greater than 0.65, preferably 0.7 to 0.75;

[0012] And / or, the mass percentage of iron in the recycled abrasive is less than 1%, preferably less than 0.2%.

[0013] According to one embodiment of the present invention, the recycled abrasive comprises diamond or silicon carbide;

[0014] And / or, the recovered abrasive is an abrasive recovered from oily cutting waste slurry.

[0015] In another aspect of the present invention, a method for recovering the recovered abrasive is provided, comprising the following steps:

[0016] (1) performing solid-liquid separation on the oily cutting waste slurry to obtain oil sludge;

[0017] (2) uniformly dispersing the oil sludge in an environmentally friendly hydrocarbon cleaning agent to obtain liquid A;

[0018] (3) removing impurities from the liquid A and drying it to obtain an abrasive.

[0019] According to one embodiment of the present invention, the environmentally friendly hydrocarbon cleaning agent is an alkane cleaning agent;

[0020] Preferably, the environmentally friendly hydrocarbon cleaning agent includes C7 to C20 alkanes;

[0021] Preferably, the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 85-95%, and the mass percentage of C12-C20 alkanes is 5-15%.

[0022] According to one embodiment of the present invention, the solid-liquid ratio of the oil sludge to the environmentally friendly hydrocarbon cleaning agent is 1 kg: (1-4) L, preferably 1 kg: (2-3) L;

[0023] and / or, the stirring speed during dispersion is 500 to 1500 rpm, preferably 800 to 1000 rpm;

[0024] And / or, the stirring time during dispersion is 1 to 4 hours.

[0025] According to one embodiment of the present invention, step (3) comprises:

[0026] (3.1) performing magnetic separation to remove iron and sedimentation on the liquid A to obtain slurry A;

[0027] (3.2) uniformly dispersing the slurry A in the environmentally friendly hydrocarbon cleaning agent and allowing it to settle, and repeating the process multiple times to obtain slurry B;

[0028] (3.3) Drying the slurry B to obtain the abrasive.

[0029] According to one embodiment of the present invention, the magnetic force during magnetic separation is greater than 3000 GS, preferably 6000 to 8000 GS.

[0030] According to one embodiment of the present invention, the sedimentation time in step (3.1) is 8-24 hours, preferably 15-20 hours.

[0031] According to one embodiment of the present invention, the solid-liquid ratio of the slurry A to the environmentally friendly hydrocarbon cleaning agent is 1 kg: (1-3) L, preferably 1 kg: 3 L.

[0032] According to one embodiment of the present invention, the sedimentation time in step (3.2) is 4 to 10 hours, preferably 5 to 8 hours.

[0033] The present invention provides a recovered abrasive and a recovery method thereof. On the one hand, the residual alkane organic matter in the recovered abrasive can improve the affinity between the abrasive and the oily cutting fluid, so that the contact angle of the recovered abrasive is no higher than 55°, thereby allowing the recovered abrasive to be evenly dispersed in the oily cutting fluid, reducing the probability of the abrasive scratching high-performance materials and improving the cutting effect. The present invention uses an environmentally friendly hydrocarbon cleaning agent to recover the abrasive from the oily cutting waste slurry. The environmentally friendly hydrocarbon cleaning agent can not only remove the oily substances in the oily cutting waste slurry, but also achieve uniform dispersion of solid particles, which is beneficial for subsequent impurity removal, so that the recovered abrasive has high purity. In addition, no concentrated acid is used in the recovery process, which is environmentally friendly and safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a SEM image of the oil sludge in the embodiment of this application;

[0035] Figure 2 TG graph of the diamond powder recovered in Example 1;

[0036] Figure 3 is a PSA graph of the diamond powder recovered in Example 1;

[0037] Figure 4 is a SEM image of the diamond powder recovered in Example 1;

[0038] Figure 5 TG graph of the diamond powder recovered in Example 2;

[0039] Figure 6 is a PSA graph of the diamond powder recovered in Example 2;

[0040] Figure 7 is a SEM image of the diamond powder recovered in Example 2;

[0041] Figure 8 TG graph of the diamond powder recovered in Example 3;

[0042] Figure 9 is the PSA graph of the diamond powder recovered in Example 3;

[0043] Figure 10 is a SEM image of the diamond powder recovered in Example 3, wherein: Figure 10 The magnification of a is 2000, Figure 10 The magnification of b is 4000;

[0044] Figure 11 TG graph of the diamond powder recovered in Example 4;

[0045] Figure 12 is a PSA graph of the diamond powder recovered in Example 4;

[0046] Figure 13 is a SEM image of the diamond powder recovered in Example 4;

[0047] Figure 14 TG graph of the diamond powder recovered in Example 5;

[0048] Figure 15 is a PSA graph of the diamond powder recovered in Example 5;

[0049] Figure 16 is a SEM image of the diamond powder recovered in Example 5;

[0050] Figure 17 TG graph of the diamond powder recovered in Example 6;

[0051] Figure 18 is a PSA graph of the diamond powder recovered in Example 6;

[0052] Figure 19 is a SEM image of the diamond powder recovered in Example 6;

[0053] Figure 20 TG graph of the diamond powder recovered in Example 7;

[0054] Figure 21 is a PSA graph of the diamond powder recovered in Example 7;

[0055] Figure 22 is a SEM image of the diamond powder recovered in Example 7;

[0056] Figure 23 TG graph of the diamond powder recovered in Example 8;

[0057] Figure 24 is a PSA graph of the diamond powder recovered in Example 8;

[0058] Figure 25 is a SEM image of the diamond powder recovered in Example 8;

[0059] Figure 26 TG chart of the diamond powder recovered in Example 9;

[0060] Figure 27 is a PSA graph of the diamond powder recovered in Example 9;

[0061] Figure 28 is a SEM image of the diamond powder recovered in Example 9;

[0062] Figure 29 This is the TG diagram of diamond raw powder;

[0063] Figure 30 Schematic diagram of the contact angle between diamond powder and oily cutting fluid;

[0064] Figure 31 Schematic diagram of the contact angle between the diamond powder recovered in Example 3 and the oily cutting fluid;

[0065] Figure 32 This is the SEM image of diamond raw powder, where: Figure 32 The magnification of a is 1500, Figure 32 The magnification of b is 4000. DETAILED DESCRIPTION

[0066] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0067] The present invention provides a recycled abrasive comprising an alkane organic compound, wherein the contact angle of the recycled abrasive is no greater than 55°. The residual alkane organic compound in the recycled abrasive can improve the abrasive's affinity for oily cutting fluids, thereby ensuring that the contact angle of the recycled abrasive is no greater than 55°. This allows the recycled abrasive to be evenly dispersed in the oily cutting fluid, thereby reducing the probability of scratching high-performance materials and improving cutting performance. The contact angle of the recycled abrasive refers to the contact angle between the recycled abrasive and the oily cutting fluid.

[0068] The main component of the oily cutting fluid of the present invention is alkane. For example, the main component of the oily cutting fluid is C12 to C40 alkane.

[0069] In a specific embodiment, the mass percentage of the alkane organic matter in the abrasive is less than or equal to 6%, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, or 6%. Preferably, the mass percentage of the alkane organic matter in the abrasive is less than or equal to 3%. When the mass percentage of the alkane organic matter in the abrasive is within the above range, the affinity of the recovered abrasive in the oily cutting fluid can be improved, so that the recovered abrasive can be evenly dispersed in the oily cutting fluid, thereby reducing the probability of scratching the high-performance material and improving the cutting effect.

[0070] The mass percentage of alkanes in the recycled abrasive can be measured using thermogravimetric (TG) analysis. For example, the weight loss of the recycled abrasive in the temperature range of 100°C to 550°C can be used as the weight of the alkanes in the recycled abrasive. Combined with the total amount of recycled abrasive measured, the mass percentage of alkanes in the recycled abrasive can be calculated.

[0071] The alkane organic matter remaining in the recovered abrasive of the present invention may be C12 to C20 alkanes.

[0072] In one embodiment, the contact angle of the recycled abrasive is 25° to 55°, for example, 25°, 30°, 35°, 40°, 45°, 50°, or 55°, preferably 30° to 55°. When the contact angle of the recycled abrasive is within the above range, the recycled abrasive is more easily dispersed in the oily cutting fluid.

[0073] In one embodiment, the angle of repose of the recycled abrasive is greater than 40° and less than or equal to 60°, such as 45°, 50°, 55°, or 60°. Preferably, the angle of repose of the recycled abrasive is greater than 40° and less than or equal to 50°. When the angle of repose of the recycled abrasive is within the above range, the recycled abrasive is more easily dispersed in the oil-based cutting fluid.

[0074] In a specific embodiment, the particle size D50 of the recycled abrasive is 6 to 8 μm, for example, 6 μm, 6.4 μm, 6.8 μm, 7 μm, 7.2 μm, 7.6 μm or 8 μm, preferably 6.5 to 7.5 μm; and / or the sphericity of the recycled abrasive is greater than 0.65, for example, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75 or 0.76, preferably 0.7 to 0.75. When the particle size and / or sphericity of the recycled abrasive are within the above ranges, the abrasive is less likely to scratch wafers of high-performance materials, reduces wear on steel wires, reduces the rate of introduction of iron impurities, and increases the service life of the cutting slurry.

[0075] In one embodiment, the weight percentage of iron in the recycled abrasive is less than 1%, preferably less than 0.2%.

[0076] The iron content in the recycled abrasive can be detected by inductively coupled plasma (ICP).

[0077] In a specific embodiment, the recycled abrasive is an abrasive recovered from oily cutting waste slurry.

[0078] The oily cutting waste slurry of the present invention refers to a cutting slurry obtained by mixing an oily cutting fluid and an abrasive, and is the waste slurry obtained after cutting high-performance materials. For example, the oily cutting waste slurry can be silicon carbide cutting waste slurry.

[0079] The present invention does not specifically limit the high-performance material. For example, the high-performance material may be silicon carbide, silicon, or sapphire.

[0080] In a specific embodiment, the recovered abrasive includes diamond or silicon carbide. For example, when the oily cutting waste slurry is silicon carbide cutting waste slurry, the recovered abrasive is diamond.

[0081] The present invention provides a method for recovering the above-mentioned recovered abrasive, comprising the following steps:

[0082] (1) performing solid-liquid separation on the oily cutting waste slurry to obtain oil sludge;

[0083] (2) uniformly dispersing the oil sludge in an environmentally friendly hydrocarbon cleaning agent to obtain liquid A;

[0084] (3) Liquid A is cleaned and dried to obtain abrasive.

[0085] The present invention does not impose any particular limitation on the method of solid-liquid separation. For example, any one of centrifugal separation, membrane separation, and gravity sedimentation may be used, with centrifugal separation being preferred.

[0086] Specifically, when centrifugal separation is used to separate the oily cutting waste slurry into solid and liquid, the present invention does not specifically limit the centrifugal speed and time. For example, the centrifugal speed is 2000-3000 r / min, specifically, the centrifugal speed is 2000 r / min, 2500 r / min or 3000 r / min, preferably 3000 r / min; the centrifugal time is 6-20 hours, specifically, the centrifugal time is 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours, preferably 10-12 hours.

[0087] The present invention does not specifically limit the solid content of the oily cutting waste slurry. For example, the solid content of the oily cutting waste slurry is 20-35%. Specifically, the solid content of the oily cutting waste slurry is 20%, 25%, 30% or 35%, preferably 30-35%.

[0088] The components of the sludge may include: abrasive, high-performance material debris, iron filings, and residual oily components. The present invention does not specifically limit the content of each component in the sludge. For example, the sludge may include 30-50% abrasive, 10-20% high-performance material debris, 30-40% iron filings, and 5-20% residual oily components. Preferably, the sludge may include: 35-50% abrasive, 10-15% high-performance material debris, 30-35% iron filings, and 10-20% residual oily components.

[0089] The present invention does not specifically limit the main substance of the oily components in the oil sludge. For example, the main component of the oil sludge can be C12-C40 alkanes. Preferably, the main component of the oil sludge can include: one or more of C12-C40 saturated straight-chain alkanes, C12-C40 saturated branched-chain alkanes, and C12-C40 cycloalkanes.

[0090] The present invention does not specifically limit the processing volume of the oily cutting waste slurry in step (1). For example, the single processing volume of the circulating centrifugation is greater than 100L, such as 150L, 200L, 250L, 300L, 450L or 500L, etc., preferably 200L.

[0091] In step (2), the oil sludge is added to the environmentally friendly hydrocarbon cleaning agent and stirred so that the oily substances and solid particles remaining in the oil sludge are uniformly dispersed in the environmentally friendly hydrocarbon cleaning agent to obtain liquid A. That is, the environmentally friendly hydrocarbon cleaning agent can dissolve the oily components in the oil sludge, so that the solid particles in the oil sludge can be uniformly dispersed in the environmentally friendly hydrocarbon cleaning agent.

[0092] The present invention does not impose any particular limitation on the stirring method. For example, any one of mechanical stirring, ultrasonic stirring, magnetic stirring, and gas stirring may be used.

[0093] The liquid A of the present invention has no obvious agglomerated particles, and the solid particles in the oil sludge are uniformly dispersed in the environmentally friendly hydrocarbon cleaning agent.

[0094] In a specific embodiment, in step (2), the environmentally friendly hydrocarbon cleaning agent is an alkane cleaning agent, that is, the main component of the alkane cleaning agent is alkane, and the mass percentage of alkane in the alkane cleaning agent is 99%-100%; preferably, the environmentally friendly hydrocarbon cleaning agent includes C7-C20 alkanes, that is, the main component of the environmentally friendly hydrocarbon cleaning agent is C7-C20 alkanes. C7-C20 alkanes include one or more of C7-C20 saturated straight-chain alkanes, C7-C20 saturated branched-chain alkanes, and C7-C20 cycloalkanes.

[0095] The intermolecular forces of non-polar substances are primarily dispersion forces, and the closer the dispersion forces, the easier it is to dissolve them. Leveraging this property, a cleaning agent with a dispersion force similar to that of the base oil can dissolve the base oil and achieve uniform particle dispersion. Currently, cutting fluids are based on saturated alkane base oils, consisting of various saturated alkanes ranging from C12 to C40. Alkanes after C20 contain multiple branches (the presence of branches weakens intermolecular attraction and reduces dispersion forces), so the dispersion forces of the base oil are primarily composed of C12-C20 saturated straight-chain alkanes. Therefore, the environmentally friendly hydrocarbon cleaning agent used in this invention uses C7-C20 alkanes as its primary component, enabling better dissolution of residual oily substances in the slurry.

[0096] Preferably, the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 85-95%, and the mass percentage of C12-C20 alkanes is 5-15%. The C7-C11 alkanes include one or more of C7-C11 saturated straight-chain alkanes, C7-C11 saturated branched-chain alkanes, and C7-C11 cycloalkanes, and the C12-C20 alkanes include one or more of C12-C20 saturated straight-chain alkanes, C12-C20 saturated branched-chain alkanes, and C12-C20 cycloalkanes. The shorter the carbon chain length of the alkane, the more volatile it is. Using short-chain alkanes as solvents is less likely to leave residue on the surface of the recovered abrasive. Environmentally friendly hydrocarbon cleaning agents are mainly composed of short-chain saturated alkanes, with a viscosity of less than 5 Pa·s, a very low boiling point, and are easily volatile (C7-C11 alkanes burn off below 150°C).

[0097] In a specific embodiment, in step (2), the solid-liquid ratio of the oil sludge to the environmentally friendly hydrocarbon cleaning agent is 1 kg: (1-4) L, for example, 1 kg: 1 L, 1 kg: 2 L, 1 kg: 3 L or 1 kg: 4 L, preferably 1 kg: (2-3) L. When the solid-liquid ratio of the oil sludge to the environmentally friendly hydrocarbon cleaning agent meets the above range, the oily components in the oil sludge can be better dissolved in the environmentally friendly hydrocarbon cleaning agent, thereby allowing the solid particles in the oil sludge to be more evenly dispersed in the environmentally friendly hydrocarbon cleaning agent, providing favorable conditions for subsequent impurity removal and greatly promoting the subsequent purification process effect.

[0098] In one embodiment, in step (2), the stirring speed during dispersion is 500 to 1500 rpm, for example, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm or 1500 rpm, preferably 800 to 1000 rpm;

[0099] In a specific embodiment, in step (2), the stirring time during dispersion is 1 to 4 hours, such as 1 hour, 2 hours, 3 hours or 4 hours, preferably 4 hours.

[0100] In one embodiment, step (3) comprises the following steps:

[0101] (3.1) Liquid A is subjected to magnetic separation to remove iron and sediment to obtain slurry A;

[0102] (3.2) Slurry A is evenly dispersed in an environmentally friendly hydrocarbon cleaning agent and allowed to settle, and the process is repeated multiple times to obtain slurry B;

[0103] (3.3) Drying slurry B to obtain abrasive.

[0104] The present invention does not specifically limit the equipment for magnetic separation and iron removal. For example, any one of a magnetic separator, a magnetic drum, and a magnetic filter can be used.

[0105] When a magnetic drum is used for magnetic separation and iron removal, the present invention does not impose any specific limitation on the drum speed. For example, the drum speed is 5 to 10 rpm. Specifically, the drum speed is 5 rpm, 6 rpm, 7 rpm, 8 rpm, 9 rpm, or 10 rpm, preferably 6 to 8 rpm.

[0106] The present invention does not specifically limit the time of magnetic separation. For example, the time of magnetic separation is greater than 10 minutes. Preferably, the time of magnetic separation is greater than 20 minutes. Theoretically, the longer the magnetic separation time, the better the iron removal effect.

[0107] In the magnetic separation step, in order to improve the magnetic separation efficiency, a stirring function can be added to the equipment to make the particles more evenly dispersed in the solution to improve the magnetic separation efficiency.

[0108] The present invention does not specifically limit the amount of liquid A. For example, the amount of liquid A is 20 to 50 L. Specifically, the amount of liquid A is 20 L, 30 L, 40 L or 50 L, preferably 30 to 40 L.

[0109] The present invention does not impose any particular limitation on the method of sedimentation. For example, gravity sedimentation or centrifugal sedimentation may be used, with gravity sedimentation being preferred.

[0110] The present invention does not specifically limit the amount of liquid sedimentation in a single time. For example, the amount of liquid sedimentation in a single time is 20 to 50 L. Specifically, the amount of liquid sedimentation in a single time is 20 L, 30 L, 40 L or 50 L, preferably 20 L.

[0111] In step (3.2), slurry A is added to an environmentally friendly hydrocarbon cleaning agent and stirred to remove the residual oily components in slurry A. Subsequently, the debris of the high-performance material can be removed by controlling the sedimentation time.

[0112] The present invention does not specifically limit the stirring speed. For example, the stirring speed is 500 to 1000 rpm. Specifically, the stirring speed is 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm or 1000 rpm, preferably 800 to 1000 rpm.

[0113] The present invention does not specifically limit the stirring time. For example, the stirring time is 1 to 4 hours. Specifically, the stirring time is 1 hour, 2 hours, 3 hours or 4 hours, preferably 2 to 3 hours.

[0114] The present invention does not specifically limit the number of repetitions of step (3.2). For example, the number of repetitions is 3 to 5 times. Specifically, the number of repetitions is 3, 4 or 5 times, preferably 3 to 4 times.

[0115] The present invention does not specifically limit the drying conditions. For example, the drying temperature is 100-150° C., specifically, the drying temperature is 100° C., 200° C., 300° C., 400° C. or 500° C., preferably 150° C. The drying time is 10-24 h, specifically, the drying time is 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h or 24 h, preferably 15-24 h.

[0116] The present invention does not specifically limit the amount of slurry B dried once. For example, the amount of slurry B dried once is 0.5-5 kg. Specifically, the amount of slurry B dried once is 0.5 kg, 1 kg, 2 kg, 3 kg, 4 kg or 5 kg, preferably 2-3 kg.

[0117] In one embodiment, in step (3.1), the magnetic force during magnetic separation is greater than 3000 GS, for example, 4000 GS, 5000 GS, 6000 GS, 7000 GS, 8000 GS, or 9000 GS, preferably 6000-8000 GS. Theoretically, the greater the magnetic force during magnetic separation, the better the iron removal effect.

[0118] After magnetic separation, the iron content in liquid A is less than 1%, preferably, the iron content in liquid A is less than 0.2%.

[0119] In a specific embodiment, the sedimentation time in step (3.1) is 8 to 24 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, preferably 15 to 20 hours. Due to the difference in particle size between the abrasive and the high-performance material, the sedimentation time can be controlled so that the abrasive with larger particle size settles to the bottom, while the fragments of the high-performance material with smaller particle size and the crushed abrasive fragments are suspended in the solution and removed together, thereby obtaining an abrasive with high purity and high uniformity at the bottom.

[0120] In one specific embodiment, in step (3.2), the solid-to-liquid ratio of slurry A to the environmentally friendly hydrocarbon cleaning agent is 1 kg:(1-3) L, for example, 1 kg:1 L, 1 kg:2 L, or 1 kg:3 L, preferably 1 kg:3 L. After iron removal, a small amount of oily components and high-performance material debris remain in slurry A. These residual oily components can also remain in the abrasive after high-temperature drying, causing abrasive powder to agglomerate and affecting abrasive reusability. By adding an environmentally friendly hydrocarbon cleaning agent to slurry A and performing repeated cleaning, the small amount of residual oily components can be deeply removed, improving the purity of the abrasive.

[0121] In one embodiment, the sedimentation time in step (3.2) is 4 to 10 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours, preferably 5 to 8 hours. When the sedimentation time is within the above range, it can be more conducive to removing impurities and further improving the purity of the abrasive.

[0122] The debris content of the high-performance material in slurry B is less than 5%, and the particle size D50 of the abrasive is 6-8 μm; preferably, the debris content of the high-performance material in slurry B is less than 1%, and the particle size D50 of the abrasive is 6.5-7.5 μm.

[0123] The recycling method of the present invention is described in detail below through specific embodiments. In the following examples, the oily cutting waste slurry is silicon carbide wafer cutting waste slurry, and the abrasive is diamond.

[0124] Example 1

[0125] The steps for recovering diamond powder from waste slurry during silicon carbide wafer cutting are as follows:

[0126] 1. Take 100L of silicon carbide wafer cutting waste slurry and centrifuge it at 3000r / min for 12h to obtain 30kg of oil sludge. Sampling and TG testing are performed to detect the content of each component. The content of cutting oil (main component C12~C40 alkane) is about 18.22%, the content of diamond is 47.87%, and the content of residual silicon carbide and iron chips is 33.91%. The SEM of the oil sludge is as follows: Figure 1 shown.

[0127] 2. Take 5 kg of the sludge obtained in step 1 and add 10 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 alkanes (the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 95% and the mass percentage of C12-C20 alkanes is 5%) at a ratio of 1 kg:2 L. Stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in the liquid and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0128] 3. Liquid A obtained in step 2 was poured into a 6000G drum magnetic separator and magnetically separated at a drum speed of 10 r / min for 15 minutes. The iron filings in the liquid were adsorbed on the magnetic drum, and the adsorbed iron filings and the iron-removed Liquid B were obtained. The adsorbed iron filings weighed 1.14 kg after drying and weighing.

[0129] 4. Liquid B obtained in step 3 was subjected to sedimentation treatment. After steps 2 and 3, most of the suspended oily substances in liquid B were removed, allowing the solid particles in liquid B to settle under gravity for 15 hours to obtain bottom sediment slurry A. After ICP testing, the iron content in slurry A was less than 1%.

[0130] 5. Add the environmentally friendly hydrocarbon cleaning agent obtained in step 2 to the slurry A obtained in step 4 at a ratio of 1 kg: 2 L, and stir at a speed of 700 r / min for 2 hours to evenly disperse the residual diamonds and silicon carbide and completely dissolve the trace amount of oily substances remaining in the particles. Then, use the gravity difference to allow the sedimentation to stand for 5 hours to precipitate diamonds with a particle size greater than 1 μm to the bottom, and diamond fragments and silicon carbide fragments smaller than 1 μm are suspended in the aqueous solution. Repeat this process three times to obtain the bottom precipitation slurry B.

[0131] 6. Spread the slurry B obtained in step 5 on a tray, dry it at 150°C for 12 hours, and then press the powder lightly to obtain dry, loose, light yellow diamond powder.

[0132] The recovered powder weighed 2.18 kg, and the diamond recovery rate was about 91.1% (recovered powder weight / oil sludge weight*theoretical diamond content of the test); after thermogravimetric analysis, the diamond content was 95.19%, the solid residue was 3.51%, and the alkane content was 1.3% (such as Figure 2 As shown), meeting the re-cutting requirements of silicon carbide ingots; ICP test results are: Al58ppmAs<3ppm, Ca 185ppm, Co 1ppm, Cr 6ppm, Fe 799ppm, Mg 97ppm, Mn5ppm.Ni11ppm, W 128ppm, Zr 3ppm, Na 129ppm; PSA particle size distribution is: D10 at 5.01μm, D50 at 7.04μm, D90 at 10.50μm (as shown Figure 3 As shown), the SEM image of diamond is as follows Figure 4 The above purity and particle size distribution can meet the requirements for re-cutting of silicon carbide ingots.

[0133] Example 2

[0134] Diamond powder in silicon carbide wafer cutting waste slurry was recovered. Compared with Example 1, the processing capacity was increased to 8 kg and the magnetic separation time was increased to 20 min. The specific steps were as follows:

[0135] 1. Same as step 1 in Example 1.

[0136] 2. Take 8 kg of the sludge obtained in step 1 and add 16 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 (the mass percentage of C7-C11 alkanes in C7-C20 alkanes is 95% and the mass percentage of C12-C20 alkanes is 5%) at a ratio of 1 kg:2 L. Stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in Liquid A and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0137] 3. Liquid A obtained in step 2 was poured into a drum magnetic separator with a magnetic force of 6000G. The drum was magnetically separated at a speed of 10 r / min for 20 min. All iron filings in the liquid were adsorbed on the magnetic drum, and the adsorbed iron filings and the iron-removed liquid B were obtained. The adsorbed iron filings weighed 2 kg after drying and weighing.

[0138] 4. Liquid B obtained in step 3 was subjected to sedimentation treatment. After steps 2 and 3, most of the suspended oily matter in liquid B was removed, allowing the solid particles in liquid B to settle under gravity for 18 hours to obtain bottom sediment slurry A. After ICP testing, the iron content in slurry A was less than 1%.

[0139] 5-6. Same as steps 5-6 of Example 1. The recovered powder weighed 3.5 kg and the diamond recovery rate was about 91.4%. After thermogravimetric analysis, the diamond content was 95.02%, the solid residue was 3.43%, and the alkane content was 1.55% (as shown in FIG. Figure 5 As shown); ICP test results are: Al 18ppm, As <3ppm, Ca 150ppm, Co <1ppm, Cr 5ppm, Fe710ppm, Mg 88ppm, Mn 4ppm, Ni <1ppm, W <3ppm, Zr <2ppm, Na 103ppm; PSA particle size distribution is: D10 at 5.03μm, D50 at 7.05μm, D90 at 10.47μm (as ... Figure 6 As shown), the SEM image of diamond is as follows Figure 7 The above purity and particle size distribution can meet the requirements for re-cutting of silicon carbide ingots.

[0140] Example 3

[0141] Diamond powder was recovered from the waste slurry from silicon carbide wafer cutting. Compared with Example 2, the solid-liquid ratio of the slurry to the solvent during stirring was increased to 1 kg:3 L. The specific steps were as follows:

[0142] 1. Same as step 1 in Example 1.

[0143] 2. Take 8 kg of the oil sludge obtained in step 1, add 24 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 (the mass percentage of C7-C11 alkanes in C7-C20 alkanes is 95%, and the mass percentage of C12-C20 alkanes is 5%) at a ratio of 1 kg:3 L, and stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in the liquid and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0144] 3. Same as step 3 of Example 2. The adsorbed iron filings weigh 1.98 kg after drying and weighing.

[0145] 4. Liquid B obtained in step 3 was subjected to sedimentation treatment. After steps 2 and 3, most of the suspended oily substances in liquid B were removed, allowing the solid particles in liquid B to settle under gravity for 20 hours to obtain bottom sediment slurry A. After ICP testing, the iron content in slurry A was less than 1%.

[0146] 5. Continue to add the environment-friendly hydrocarbon cleaning agent in Step 2 to the slurry A obtained in Step 4 at a ratio of 1 kg: 3 L, stir at a speed of 700 r / min for 2 h, so that the residual diamond and silicon carbide are uniformly dispersed and the trace oily substances remaining in the particles are completely dissolved. Then, let it stand and settle for 5 h using the gravity difference. The diamond with a particle size greater than 1 μm precipitates to the bottom, and the diamond debris and silicon carbide debris with a particle size less than 1 μm are suspended in the aqueous solution. After repeating 3 times, the bottom precipitate slurry B is obtained.

[0147] 6. The same as Step 6 of Example 1. Among them, the weight of the recovered powder after weighing is 3.56 kg, and the recovery rate of diamond is about 92.9%; after performing thermogravimetric analysis and detection, its diamond content is 96.61%, the solid residue content is 1.80%, and the alkane content is 1.59% ( Figure 8 ); the detection results of ICP are: Al 28 ppm, As < 3 ppm, Ca 109 ppm, Co < 1 ppm, Cr < 1 ppm, Fe 669 ppm, Mg 28 ppm, Mn < 1 ppm, Ni < 1 ppm, W 24 ppm, Zr < 2 ppm, Na 74 ppm; the PSA particle size distribution is: D10 is 5.01 μm, D50 is 6.92 μm, D90 is 10.07 μm ( Figure 9 ), and the scanning electron microscope SEM image of diamond is as shown in Figure 10 . The above purity and particle size distribution can both meet the requirements for re-cutting of silicon carbide ingots.

[0148] Example 4

[0149] Recover diamond powder from the silicon carbide wafer cutting waste mortar. Compared with Example 1, shorten the stirring and dispersion time in Step 2. The specific steps are as follows:

[0150] 1. The same as Step 1 of Example 1.

[0151] 2. Take 5 kg of the sludge obtained in Step 1, add 10 L of an environment-friendly hydrocarbon cleaning agent with a main component of C7 - C20 (in C7 - C20 alkanes, the mass percentage of C7 - C11 alkanes is 95%, and the mass percentage of C12 - C20 alkanes is 5%) at a ratio of 1 kg: 2 L, and stir at 800 rpm / min for 1 h to obtain Liquid A.

[0152] 3. The same as Step 3 of Example 2. Among them, the weight of the adsorbed iron filings after drying and weighing is 1.25 kg.

[0153] 4. Perform a 15 - h sedimentation treatment on the Liquid B obtained in Step 3 to obtain the bottom precipitate slurry A. After ICP detection, the iron content in the slurry A is less than 1%.

[0154] 5. Continue to add the environment-friendly hydrocarbon cleaning agent in Step 2 to the slurry A obtained in Step 4 at a ratio of 1 kg: 2 L, stir at a speed of 700 r / min for 1 h to uniformly disperse the residual diamond and silicon carbide and completely dissolve the trace oily substances remaining in the particles, then let it stand and settle for 5 h using the gravity difference to precipitate the diamond with a particle size greater than 1 μm to the bottom, and the diamond debris and silicon carbide debris with a particle size less than 1 μm will be suspended in the aqueous solution. After repeating 3 times, the bottom precipitate slurry B is obtained.

[0155] 6. The same as Step 6 of Example 1. Among them, the weight of the recovered powder after weighing is 2.05 kg, and the recovery rate is about 85.6%; after performing thermogravimetric analysis and detection, its diamond content is 89.11%, the solid residue content is 8.26%, and the alkane content is 2.63% ( Figure 11 ); the detection results of ICP are: Al 10 ppm, As < 3 ppm, Ca 72 ppm, Co < 1 ppm, Cr < 1 ppm, Fe 970 ppm, Mg 12 ppm, Mn 7 ppm, Ni < 1 ppm, W 50 ppm, Zr < 2 ppm, Na 34 ppm; the PSA particle size distribution is: D10 is 4.99 μm, D50 is 7.01 μm, D90 is 10.42 μm ( Figure 12 ), and the SEM image of the diamond is as shown in Figure 13 . The above purity and particle size distribution can both meet the requirements for re-cutting silicon carbide ingots.

[0156] Example 5

[0157] Recover the diamond powder from the silicon carbide wafer cutting waste mortar. Compared with Example 1, replace the alkane cleaning agent with a longer chain length. The steps are as follows:

[0158] 1. The same as Step 1 of Example 1.

[0159] 2. Take 5 kg of the oil sludge obtained in Step 1, add 10 L of environment-friendly hydrocarbon cleaning agent at a ratio of 1 kg: 2 L (where the mass percentage of C20 - C25 alkanes is 99 - 99.9%, and the mass percentage of aromatics is 0.1 - 1%), and stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in Liquid A and the particles are uniformly dispersed in the liquid to obtain Liquid A.

[0160] 3. The same as Step 3 of Example 1. Among them, the weight of the adsorbed iron filings after drying and weighing is 1.18 kg.

[0161] 4. The same as Step 4 of Example 2.

[0162] 5-6. Same as steps 5-6 of Example 1. The recovered powder weighed 1.8 kg, and the diamond recovery rate was about 75.2% (recovered powder weight / oil sludge weight*theoretical diamond content detected); after thermogravimetric analysis, the diamond content was 87.02%, the solid residue was 6.98%, and the alkane content was 6.0% ( Figure 14 ); ICP test results are: Al 58ppm, As <3ppm, Ca107ppm, Co 20ppm, Cr 41ppm, Fe 1668ppm, Mg 87ppm, Mn 30ppm, Ni20ppm, W <3ppm, Zr <2ppm, Na 124ppm; PSA particle size distribution is: D10 at 4.46μm, D50 at 6.64μm, D90 at 9.88μm ( Figure 15 ), the SEM image of diamond is as follows Figure 16 The above purity and particle size distribution can meet the requirements for re-cutting of silicon carbide ingots, but the cutting life is short.

[0163] Example 6

[0164] Diamond powder in waste slurry from silicon carbide wafer cutting is recovered. Compared with Example 1, the composition of the environmentally friendly hydrocarbon cleaning agent in step 2 is different. The specific steps are as follows:

[0165] 1. Same as step 1 in Example 1.

[0166] 2. Take 5 kg of the sludge obtained in step 1 and add 10 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 alkanes (the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 85%, and the mass percentage of C12-C20 alkanes is 15%) at a ratio of 1 kg:2 L. Stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in the liquid and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0167] 3. Same as step 3 of Example 1. The adsorbed iron filings weigh 1.2 kg after drying and weighing.

[0168] 4. Same as step 4 in Example 2.

[0169] 5-6. Same as steps 5-6 of Example 1. The recovered powder weighed 2.17 kg and the diamond recovery rate was about 90.66%. After thermogravimetric analysis, the diamond content was 92.74%, the solid residue was 4.36%, and the alkane content was 2.90% (as shown in FIG. Figure 17As shown), it meets the re-cutting requirements of silicon carbide ingots; the ICP test results are: Al43ppmAs<3ppm, Ca140ppm, Co 2ppm, Cr 3ppm, Fe 939ppm, Mg32ppm, Mn 7ppm.Ni<1ppm, W228ppm, Zr<2ppm, Na 105ppm; PSA particle size distribution is: D10 is 5.01μm, D50 is 7.04μm, D90 is 10.32μm (as shown Figure 18 As shown), the SEM image of diamond is as follows Figure 19 shown.

[0170] Example 7

[0171] Diamond powder in waste slurry from silicon carbide wafer cutting is recovered. Compared with Example 1, the composition of the environmentally friendly hydrocarbon cleaning agent in step 2 is different. The specific steps are as follows:

[0172] 1. Same as step 1 in Example 1.

[0173] 2. Take 5 kg of the sludge obtained in step 1, add 10 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 alkanes (the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 90%, and the mass percentage of C12-C20 alkanes is 10%) at a ratio of 1 kg:2 L, and stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in the liquid and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0174] 3. Same as step 3 of Example 1. The adsorbed iron filings weigh 1.15 kg after drying and weighing.

[0175] 4. Same as step 4 in Example 2.

[0176] 5-6. Same as steps 5-6 of Example 1. The recovered powder weighed 2.20 kg and the diamond recovery rate was about 91.92%. After thermogravimetric analysis, the diamond content was 95.27%, the solid residue was 2.93%, and the alkane content was 1.80% (as shown in FIG. Figure 20 As shown), meeting the re-cutting requirements of silicon carbide ingots; ICP test results are: Al68ppm, As<3ppm, Ca243ppm, Co 4ppm, Cr 5ppm, Fe 836ppm, Mg 113ppm, Mn 5ppm.Ni 6ppm, W14ppm, Zr 3ppm, Na 836ppm; PSA particle size distribution is: D10 at 5.11μm, D50 at 7.07μm, D90 at 10.42μm (as shown Figure 21 As shown), the SEM image of diamond is as follows Figure 22 shown.

[0177] Example 8

[0178] Diamond powder in waste slurry from silicon carbide wafer cutting is recovered. Compared with Example 1, the composition of the environmentally friendly hydrocarbon cleaning agent in step 2 is different. The specific steps are as follows:

[0179] 1. Same as step 1 in Example 1.

[0180] 2. Take 5 kg of the sludge obtained in step 1 and add 10 L of an environmentally friendly hydrocarbon cleaning agent whose main component is C7-C20 alkanes (the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 80% and the mass percentage of C12-C20 alkanes is 20%) at a ratio of 1 kg:2 L. Stir at 800 rpm / min for 4 h until there are no obvious agglomerated particles in the liquid and the particles are evenly dispersed in the liquid to obtain Liquid A.

[0181] 3. Same as step 3 of Example 1. The adsorbed iron filings weigh 1.09 kg after drying and weighing.

[0182] 4. Same as step 4 in Example 2.

[0183] 5-6. Same as steps 5-6 of Example 1. The recovered powder weighed 2.00 kg and the diamond recovery rate was about 83.56%. After thermogravimetric analysis, the diamond content was 91.16%, the solid residue was 4.84%, and the alkane content was 4.00%. Figure 23 As shown), it meets the re-cutting requirements of silicon carbide ingots; the ICP test results are: Al29ppm, As<3ppm, Ca103ppm, Co<1ppm, Cr<1ppm, Fe 1886ppm, Mg 18ppm, Mn<1ppm, Ni<1ppm, W48ppm, Zr 4ppm, Na 31ppm; the PSA particle size distribution is: D10 at 4.9μm, D50 at 6.83μm, D90 at 10.15μm (as shown Figure 24 As shown), the SEM image of diamond is as follows Figure 25 shown.

[0184] Example 9

[0185] Diamond powder in waste slurry from silicon carbide wafer cutting was recovered. Compared with Example 1, the settling time was different. The specific steps were as follows:

[0186] 1-2. Same as steps 1-2 of Example 1.

[0187] 3. Same as step 3 of Example 1. The adsorbed iron filings weigh 1.15 kg after drying and weighing.

[0188] 4. Perform sedimentation treatment on the liquid B obtained in step 3. After steps 2 and 3, most of the suspended oily substances in the liquid B have been removed, allowing the solid particles in the liquid to precipitate under gravity for 10 h to obtain the bottom precipitate slurry A. After ICP detection, the iron content in the slurry A is less than 1%.

[0189] 5. Continue to add the environmentally friendly hydrocarbon cleaning agent from step 2 to the slurry A obtained in step 4 at a ratio of 1 kg: 2 L, and stir at a speed of 700 r / min for 2 h to uniformly disperse the remaining diamond and silicon carbide and completely dissolve the trace oily substances remaining in the particles. Then, let it stand and settle for 4 h using the gravity difference to precipitate the diamond with a particle size greater than 1 μm to the bottom, and the diamond debris and silicon carbide debris with a particle size less than 1 μm will be suspended in the aqueous solution. After repeating 3 times, the bottom precipitate slurry B is obtained.

[0190] 6. The same as step 6 of Example 1. Among them, the weight of the recovered powder after weighing is 2.23 g, and the recovery rate of diamond is about 93.17%; after thermogravimetric analysis and detection: the diamond content is 93.41%, the solid residue content is 5.11%, and the alkane content is 1.48% (as Figure 26 shown), meeting the requirements for re-cutting of silicon carbide ingots; the ICP detection results are: Al 22 ppm, As < 3 ppm, Ca 127 ppm, Co < 1 ppm, Cr < 1 ppm, Fe 1036 ppm, Mg 12 ppm, Mn 4 ppm, Ni < 1 ppm, W 80 ppm, Zr < 2 ppm, Na 57 ppm; the PSA particle size distribution is: D10 at 4.63 μm, D50 at 6.76 μm, D90 at 10.20 μm (as Figure 27 shown), and the SEM image of the diamond is as Figure 28 shown.

[0191] Comparative Example 1

[0192] Recover the diamond powder from the silicon carbide wafer cutting waste mortar. Compared with Example 1, it is replaced with the organic solvent polyethylene glycol for stirring and cleaning. The steps are as follows:

[0193] 1. The same as step 1 of Example 1.

[0194] 2. Take 5 kg of the oil sludge obtained in step 1, add 10 L of polyethylene glycol at a ratio of 1 kg: 2 L, and stir at 800 rpm / min for 2 h. Since the organic solvent is immiscible with the original oily components, the solution shows a layered phenomenon and fails to disperse uniformly.

[0195] It should be noted that when the unequally dispersed solution is subjected to magnetic separation and sedimentation, the subsequent magnetic separation and sedimentation effects are poor because the sludge is not evenly dispersed. Even if a recyclable material can be obtained in the end, the content of each component and performance parameters in the recyclable material are similar to those of the sludge.

[0196] Test example

[0197] 1. Thermogravimetric (TG) analysis of solid impurity residues and alkane residues

[0198] 10mg of recovered diamond and raw diamond powder were randomly sampled for thermogravimetric analysis. The temperature was set from room temperature to 1000℃, in an oxygen / air atmosphere, and the heating rate was 10℃ / min. The weight loss in the range of 100℃ to 550℃ indicates that the residual alkane cleaning agent in the diamond was burned away; there was more than one endothermic peak between 550℃ and 1000℃, and the weight remaining after the end of the 1000℃ treatment was the residual amount of solid impurities. The results are shown in Tables 1 and Figure 29 .

[0199] 2. Particle Size Distribution (PSA) Test

[0200] Randomly take 2 g of the powder sample recovered in the above example and perform wet analysis in a laser particle size analyzer. The solvent is alcohol. The particle size distribution percentages of D10, D50, and D90 are obtained. The results are shown in Table 1.

[0201] 3. Contact angle test

[0202] 20g of the powder recovered from the above examples and the original diamond powder were randomly taken for contact angle test. After the powder was pressed into a smooth plane, a drop of oily cutting fluid was dripped onto the plane. The oily cutting fluid contained 99% to 100% of various saturated alkanes of C12 to C40. The angle between the powder plane and the droplet was recorded as the contact angle test value. The results are shown in Table 1. Figure 30 and Figure 31 .

[0203] 4. The conditions for testing the angle of repose of powder are:

[0204] The powder recovered from the above examples was randomly sampled and subjected to an angle of repose test according to GB 11986-1989. The results are shown in Table 1.

[0205] Table 1

[0206]

[0207]

[0208] From Table 1 we can see that:

[0209] It can be seen from Examples 1-9 and Comparative Example 1 that the purity of the abrasive recovered by the recovery method of the present invention can reach up to 96.61%. It can be seen that the recovery method of the present invention can significantly improve the recovery purity of the abrasive, and does not require the use of concentrated acid. It has the advantages of simple process flow, safety, and low pollution, meets the feasibility of mass production, and can significantly reduce production costs (compared to diamond raw powder, at least 1,000 yuan of cost can be saved per kg of powder). In addition, the appropriate amount of alkane organic matter in the recovered abrasive of the present invention can improve the affinity between the abrasive and the oily cutting fluid, so that the recovered abrasive can be evenly dispersed in the oily cutting fluid, thereby improving the cutting effect.

[0210] pass Figure 10 and Figure 32 It can be seen from the comparison that the morphology of the recycled abrasive of the present invention is similar to that of the abrasive raw material.

[0211] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A recovered abrasive, characterized in that: The recycled abrasive includes alkane organic matter, and the contact angle of the recycled abrasive is not higher than 55°.

2. The recovered abrasive according to claim 1, characterized in that The mass percentage of the alkane organic matter in the recovered abrasive is less than or equal to 6%; Preferably, the mass percentage of the alkane organic matter in the recovered abrasive is less than or equal to 3%.

3. The recovered abrasive according to claim 1 or 2, characterized in that: The contact angle of the recycled abrasive is 25° to 55°, preferably 30° to 55°.

4. The recovered abrasive according to any one of claims 1 to 3, characterized in that: The angle of repose of the recycled abrasive is greater than 40° and less than or equal to 60°. Preferably, the angle of repose of the recycled abrasive is greater than 40° and less than or equal to 50°. and / or, the particle size D50 of the recycled abrasive is 6 to 8 μm, preferably 6.5 to 7.5 μm; and / or, the sphericity of the recycled abrasive is greater than 0.65, preferably 0.7 to 0.75; And / or, the mass percentage of iron in the recycled abrasive is less than 1%, preferably less than 0.2%.

5. The recovered abrasive according to any one of claims 1 to 4, characterized in that: The recycled abrasive includes diamond or silicon carbide; And / or, the recovered abrasive is an abrasive recovered from oily cutting waste slurry.

6. The method for recovering abrasive material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) performing solid-liquid separation on the oily cutting waste slurry to obtain oil sludge; (2) uniformly dispersing the oil sludge in an environmentally friendly hydrocarbon cleaning agent to obtain liquid A; (3) removing impurities from the liquid A and drying it to obtain an abrasive.

7. The method according to claim 6, characterized in that The environmentally friendly hydrocarbon cleaning agent is an alkane cleaning agent; Preferably, the environmentally friendly hydrocarbon cleaning agent includes C7 to C20 alkanes; Preferably, the mass percentage of C7-C11 alkanes in the C7-C20 alkanes is 85-95%, and the mass percentage of C12-C20 alkanes is 5-15%.

8. The method according to claim 6 or 7, characterized in that The solid-liquid ratio of the oil sludge to the environmentally friendly hydrocarbon cleaning agent is 1 kg: (1-4) L, preferably 1 kg: (2-3) L; and / or, the stirring speed during dispersion is 500 to 1500 rpm, preferably 800 to 1000 rpm; And / or, the stirring time during dispersion is 1 to 4 hours.

9. The method according to any one of claims 6 to 8, characterized in that: Step (3) includes: (3.1) performing magnetic separation to remove iron and sedimentation on the liquid A to obtain slurry A; (3.2) uniformly dispersing the slurry A in the environmentally friendly hydrocarbon cleaning agent and allowing it to settle, and repeating the process multiple times to obtain slurry B; (3.3) Drying the slurry B to obtain the abrasive.

10. The method according to claim 9, characterized in that The magnetic force during magnetic separation is greater than 3000 GS, preferably 6000 to 8000 GS.

11. The method according to claim 9 or 10, characterized in that The sedimentation time in step (3.1) is 8 to 24 hours, preferably 15 to 20 hours.

12. The method according to any one of claims 9 to 11, characterized in that: The solid-liquid ratio of the slurry A to the environmentally friendly hydrocarbon cleaning agent is 1 kg: (1-3) L, preferably 1 kg: 3 L.

13. The method according to any one of claims 9 to 12, characterized in that: The sedimentation time in step (3.2) is 4 to 10 hours, preferably 5 to 8 hours.

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