A method for recovering diamond powder from oily grinding waste

Abstract

The present disclosure relates to a method for recovering diamond powder from oily grinding waste, the method comprising: (1) mixing the oily grinding waste containing diamond powder and ceramic particles, a separating agent and water, filtering the resulting mixture, and then performing solid-liquid separation on the resulting filtrate to collect the precipitate; (2) mixing the precipitate, a sulfuric acid solution and ammonium sulfate and heating, and washing and drying the resulting material; wherein the separating agent comprises a surfactant, an organic carboxylate and an alkaline inorganic substance. The method uses a separating agent with a specific composition, has a high oil removal efficiency, and recovers high-purity diamond powder.

Description

Technical Field

[0001] The present disclosure relates to the technical field of mineral processing, and specifically, to a method for recovering diamond powder from oily grinding waste. Background Art

[0002] Zirconia ceramics have many advantages such as high hardness, high strength, high toughness, and good corrosion resistance, and are widely used in fields such as machinery, chemical engineering, and aerospace. However, due to the high hardness of ceramic materials, the grinding and polishing processes are relatively difficult, and the requirements for their processing quality are very high, with the surface roughness reaching the nanometer level. Diamond is the hardest substance found in nature at present and is widely used in the processing of cutting, grinding, and drilling of brittle and hard materials, such as semiconductor crystals, stones, ceramics, cemented carbides, etc. Diamond grinding is generally the second-to-last processing step, which not only requires high efficiency but also a low surface roughness and no deep scratches, so that a higher yield can be achieved in the final polishing process. Traditional mechanical grinding or polishing uses diamond grinding fluid or diamond polishing paste, and under the action of appropriate pressure, the surface of the ceramic material is ground or polished under the rapid rotation of a metal grinding disc or a disc with a polishing pad. During the grinding process, the diamond particles will gradually become finer and the particle size will gradually become smaller. These diamond particles and the oily grinding fluid or polishing paste form oily grinding waste. In the subsequent treatment of grinding waste in the prior art, only some diamond particles with larger sizes can be recovered, while the diamond powder with smaller particles cannot be recovered and can only be wasted in the subsequent waste treatment process. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a method for recovering diamond powder from oily grinding waste. This method uses a separating agent with a specific composition, has a high oil removal efficiency, and can recover diamond powder with high purity.

[0004] To achieve the above purpose, the present disclosure provides a method for recovering diamond powder from oily grinding waste, and the method includes:

[0005] (1) Mix the oily grinding waste containing diamond powder and ceramic particles, a separating agent, and water, filter the resulting mixture, and then perform solid-liquid separation on the resulting filtrate to collect the precipitate;

[0006] (2) Mix the precipitate, a sulfuric acid solution, and ammonium sulfate and heat, and wash and dry the resulting material;

[0007] Wherein, the separating agent includes a surfactant, an organic carboxylate, and an alkaline inorganic substance.

[0008] Optionally, in step (1), the weight ratio of the oily grinding waste, the separating agent and water is 1:(0.2 - 1):(10 - 20), preferably 1:(0.5 - 1):(15 - 20).

[0009] Optionally, the surfactant is a non-ionic surfactant, preferably one or more of fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, polyethylene glycol, nonylphenol polyoxyethylene ether and polyvinylpyrrolidone; the organic carboxylates include one or more of sodium succinate, sodium citrate, sodium gluconate, sodium acetate, sodium benzoate and sodium formate; the basic inorganic substances include one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate, calcium hydroxide and barium hydroxide.

[0010] Optionally, the separating agent includes fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, sodium succinate, sodium citrate, sodium gluconate, sodium carbonate, sodium hydroxide and potassium hydroxide; based on the total weight of the separating agent, the content of fatty alcohol polyoxyethylene ether is 1 - 10% by weight, the content of triethanolamine is 2 - 10% by weight, the content of polyoxyethylene glycerol ether is 2 - 10% by weight, the content of sodium succinate is 2 - 10% by weight, the content of sodium citrate is 4 - 16% by weight, the content of sodium gluconate is 2 - 8% by weight, the content of sodium carbonate is 2 - 15% by weight, the content of sodium hydroxide is 10 - 25% by weight, and the content of potassium hydroxide is 5 - 20% by weight.

[0011] Optionally, in step (2), the weight ratio of the precipitate, the sulfuric acid solution and ammonium sulfate is 1:(5 - 10):(3 - 5), preferably 1:(7 - 10):(3 - 4); based on the total weight of the sulfuric acid solution, the content of sulfuric acid is 50 - 98% by weight.

[0012] Optionally, in step (2), the heating conditions include: the temperature is 300 - 500°C, and the heat preservation time is 0.5 - 3 h. Preferably, the temperature is 300 - 400°C, and the heat preservation time is 0.5 - 2 h.

[0013] Optionally, the method further includes, before the filtration in step (1), performing a dispersion treatment on the mixture; the dispersion treatment includes mechanical stirring or ultrasonic dispersion. The conditions for mechanical stirring include: the stirring speed is 100 - 1000 r / min, and the stirring time is 10 - 30 min; the conditions for ultrasonic dispersion include: the ultrasonic frequency is 10 - 100 KHz, the ultrasonic temperature is 20 - 100°C, and the ultrasonic time is 30 - 240 min.

[0014] Optionally, the filtration includes single-stage filtration or multi-stage filtration. The pore size of the filter screen for single-stage filtration is 25-150 μm, and the pore size of the filter screen of the last stage for multi-stage filtration is 25-75 μm.

[0015] Optionally, in step (1), the solid-liquid separation includes static precipitation or centrifugal separation. The time for static precipitation is 12-48 h; the conditions for centrifugal separation include: the power of the centrifuge is 30-50 Hz, the rotation speed is 1000-12000 r / min, and the centrifugation time is 5-30 min; in step (2), the washing includes: rinsing the reaction product with pure water once or multiple times until the pH of the washing liquid is 6.5-7.5, and the drying temperature is 150-450 °C and the time is 1-3 h.

[0016] Optionally, the oily grinding waste includes diamond powder, grease, and ceramic particles. The ceramic particles include zirconia ceramics; based on the total weight of the oily grinding waste, the content of the diamond powder is 10-60% by weight, preferably 20-30% by weight; the absolute particle size of the diamond powder is 3-20 μm, preferably 3-5 μm, and the absolute particle size of the ceramic particles is 1-100 μm; preferably, the oily grinding waste is selected from oily grinding waste slurries and diamond polishing waste pastes.

[0017] Through the above technical solutions, the method for recovering diamond powder from oily grinding waste provided by the present disclosure uses a separating agent with a specific composition for chemical degreasing, which can effectively remove grease. Among them, the surfactant has a solubilization effect, which can reduce the interfacial tension between grease and water, weaken the adhesion of grease to diamond powder, and facilitate the floating of the shed grease on the liquid surface for separation; the organic carboxylate has an emulsification effect, which can disperse the grease in the aqueous solution to form an emulsion; the basic inorganic substance can decompose the animal and vegetable oils in the grease into fatty acid salts and glycerol that are easily soluble in water, and then the diamond powder can be separated from the grease through solid-liquid separation to achieve the purpose of removing oil stains; using sulfuric acid solution and ammonium sulfate for chemical impurity removal can remove ceramic impurities in the oily grinding waste, thereby recovering diamond powder with high purity. The method of the present disclosure has simple processes, high degreasing efficiency, and can effectively reduce the diamond recovery cost.

[0018] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. They are used together with the following specific implementation to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0020] Figure 1It is a scanning electron microscope image of the powder 1 prepared in Example 1 of the present disclosure. Detailed Description of the Embodiment

[0021] The following provides a detailed description of the specific embodiments of the present disclosure. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present disclosure, and are not intended to limit the present disclosure.

[0022] The present disclosure provides a method for recovering diamond powder from oily grinding waste, the method comprising:

[0023] (1) Mix an oily grinding waste containing diamond powder and ceramic particles, a separating agent, and water, filter the resulting mixture, and then perform solid-liquid separation on the resulting filtrate to collect the precipitate;

[0024] (2) Mix the precipitate, a sulfuric acid solution, and ammonium sulfate and heat, and wash and dry the resulting material;

[0025] Wherein, the separating agent comprises a surfactant, an organic carboxylate, and an alkaline inorganic substance.

[0026] The method for recovering diamond powder from oily grinding waste provided by the present disclosure uses a separating agent with a specific composition for chemical degreasing, which can effectively remove grease. The surfactant has a solubilization effect, which can reduce the interfacial tension between grease and water, weaken the adhesion of grease to diamond powder, and facilitate the floating of the detached grease on the liquid surface for separation; the organic carboxylate has an emulsifying effect, which can disperse the grease in an aqueous solution to form an emulsion; the alkaline inorganic substance can decompose the animal and vegetable oils in the grease into fatty acid salts and glycerol that are soluble in water, and then the diamond powder can be separated from the grease through solid-liquid separation to achieve the purpose of removing oil stains; using a sulfuric acid solution and ammonium sulfate for chemical impurity removal can remove ceramic impurities in the oily grinding waste, thereby recovering high-purity diamond powder. The method of the present disclosure has simple processes, high degreasing efficiency, and can effectively reduce the diamond recovery cost.

[0027] In one embodiment of the present disclosure, in step (1), the weight ratio of the oily grinding waste, the separating agent, and water is 1:(0.2 - 1):(10 - 20), preferably 1:(0.5 - 1):(15 - 20). In the above embodiment, by selecting the preferred feeding ratio, it is beneficial for the grease in the oily grinding waste to react fully with the separating agent, and to improve the cleaning, emulsifying, and degreasing ability of the separating agent.

[0028] In an embodiment of the present disclosure, the surfactant is a non-ionic surfactant, preferably one or more of fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, polyethylene glycol, nonylphenol polyoxyethylene ether, and polyvinylpyrrolidone. The organic carboxylates include one or more of sodium succinate, sodium citrate, sodium gluconate, sodium acetate, sodium benzoate, and sodium formate. The basic inorganic substances include one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate, calcium hydroxide, and barium hydroxide. In the above embodiment, by selecting the preferred surfactant, organic carboxylate, and basic inorganic substance, grease can be effectively cleaned. The surfactant and the organic carboxylate are used in combination, having an obvious synergistic effect, effectively promoting the wetting, dispersion, cleaning, and emulsification of the separating agent on the diamond powder, enabling the diamond powder to be peeled off from the grease and facilitating recovery.

[0029] In an embodiment of the present disclosure, the separating agent includes fatty alcohol polyoxyethylene ether (CAS No. 111-09-3), triethanolamine (CAS No. 102-71-6), polyoxyethylene glycerol ether (CAS No. 31694-55-0), sodium succinate (CAS No. 150-90-3), sodium citrate (CAS No. 68-04-2), sodium gluconate (CAS No. 527-07-1), sodium carbonate, sodium hydroxide, and potassium hydroxide. Based on the total weight of the separating agent, the content of fatty alcohol polyoxyethylene ether is 1-10% by weight, the content of triethanolamine is 2-10% by weight, the content of polyoxyethylene glycerol ether is 2-10% by weight, the content of sodium succinate is 2-10% by weight, the content of sodium citrate is 4-16% by weight, the content of sodium gluconate is 2-8% by weight, the content of sodium carbonate is 2-15% by weight, the content of sodium hydroxide is 10-25% by weight, and the content of potassium hydroxide is 5-20% by weight. In the above embodiment, by selecting the separating agent with the preferred composition and ratio, the wetting, dispersion, cleaning, and emulsification effects of the separating agent can be further improved.

[0030] In an embodiment of the present disclosure, in step (2), the weight ratio of the precipitate, sulfuric acid solution, and ammonium sulfate is 1:(5-10):(3-5), preferably 1:(7-10):(3-4). Based on the total weight of the sulfuric acid solution, the content of sulfuric acid is 50-98% by weight. In the above embodiment, by selecting the preferred sulfuric acid solution and ammonium sulfate, the micron-sized zirconia ceramic particles in the precipitate can be fully corroded, thereby removing impurities and obtaining high-purity diamond powder.

[0031] In one embodiment of the present disclosure, it is characterized in that in step (2), the heating conditions include: the temperature is 300 - 500 °C, and the heat preservation time is 0.5 - 3 h. Preferably, the temperature is 300 - 400 °C, and the heat preservation time is 0.5 - 2 h. In the above embodiment, by selecting the preferred heating conditions, the removal rate of ceramic particles can be further improved.

[0032] In one embodiment of the present disclosure, the method further includes dispersing the mixture before the filtration in step (1); the dispersion treatment includes mechanical stirring or ultrasonic dispersion. The conditions for mechanical stirring include: the stirring speed is 100 - 1000 r / min, and the stirring time is 10 - 30 min; the conditions for ultrasonic dispersion include: the ultrasonic frequency is 10 - 100 KHz, the ultrasonic temperature is 20 - 100 °C, and the ultrasonic time is 30 - 240 min. In the above embodiment, by selecting the preferred dispersion treatment, it is beneficial for the oil and the separating agent to fully contact and react. Among them, ultrasonic dispersion also has a cleaning effect, which utilizes the cavitation effect, acceleration effect and rectilinear flow effect of ultrasonic waves in the liquid to directly and indirectly act on the liquid and oil stains, so that the oil is dispersed, emulsified and stripped to achieve the cleaning purpose.

[0033] In one embodiment of the present disclosure, the filtration includes single-stage filtration or multi-stage filtration. The aperture of the filter screen for single-stage filtration is 25 - 150 μm, and the aperture of the filter screen for the last stage of multi-stage filtration is 25 - 75 μm. In the above embodiment, by selecting the preferred filtration operation, large-size solid impurities in the oily abrasive waste can be removed, reducing the influence of solid impurities on subsequent processing. At this time, the filtrate contains micron-sized ceramic particles and diamond powder.

[0034] In one embodiment of the present disclosure, in step (1), the solid-liquid separation includes static precipitation or centrifugal separation. The time for static precipitation is 12 - 48 h; the conditions for centrifugal separation include: the power of the centrifuge is 30 - 50 Hz, the rotation speed is 1000 - 12000 r / min, and the centrifugation time is 5 - 30 min; in step (2), the washing includes: rinsing the reaction product with pure water once or multiple times until the pH of the washing liquid is 6.5 - 7.5, and the drying temperature is 150 - 450 °C, and the time is 1 - 3 h. In the above embodiment, by selecting the preferred solid-liquid separation, the physical stratification of oil and water can be achieved, and then the upper oil layer after stratification is removed, and a precipitate without oil can be obtained; by selecting the preferred washing and drying, the impurities attached to the surface of the diamond powder can be washed away, and high-purity diamond powder can be obtained.

[0035] In one embodiment of the present disclosure, the oily grinding waste includes diamond powder, grease, and ceramic particles, and the ceramic particles include zirconia ceramics; based on the total weight of the oily grinding waste, the content of the diamond powder is 10 to 60% by weight, preferably 20 to 30% by weight; the absolute particle size of the diamond powder is 3 to 20 μm, preferably 3 to 5 μm, and the absolute particle size of the ceramic particles is 1 to 100 μm; in a preferred embodiment, the oily grinding waste is selected from oily grinding waste slurries and diamond polishing waste pastes. In the above embodiment, the main components of the oily grinding waste slurry are diamond powder, vegetable oil, mineral oil, and zirconia ceramic particles; the main components of the diamond polishing waste paste are diamond powder, lubricating grease, vegetable oil, mineral oil, and zirconia ceramic particles.

[0036] The method for recovering diamond powder from oily grinding waste provided by the present disclosure uses a separating agent with a specific composition for chemical degreasing, which can effectively remove grease. The surfactant has a solubilizing effect, which can reduce the interfacial tension between grease and water, weaken the adhesion of grease to diamond powder, and facilitate the floating of the detached grease on the liquid surface for separation; the organic carboxylate has an emulsifying effect, which can disperse the grease in an aqueous solution to form an emulsion; the alkaline inorganic substance can decompose the animal and vegetable oils in the grease into water-soluble fatty acid salts and glycerol, and then the diamond powder can be separated from the grease through solid-liquid separation to achieve the purpose of removing oil stains; the ceramic impurities in the oily grinding waste can be removed by using a sulfuric acid solution and ammonium sulfate in a chemical impurity removal method, so as to recover high-purity diamond powder. The method of the present disclosure has simple processes, high degreasing efficiency, and can effectively reduce the diamond recovery cost.

[0037] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereby.

[0038] In the following examples and comparative examples, unless otherwise specified, the raw materials used are commercially available products.

[0039] The test method for particle size is a laser particle size analyzer, and the test instrument is the LT3600S laser particle size analyzer of Zhuhai Truth Optics Instrument Co., Ltd.

[0040] Example 1

[0041] (1) Add a separating agent and pure water to 100 g of oily grinding waste slurry, with a weight ratio of 1:1:20; then perform dispersion treatment using an ultrasonic cleaning tank, with an ultrasonic frequency of 80 KHz, an ultrasonic temperature of 50 °C, and an ultrasonic time of 120 min; after the ultrasonic treatment, perform filtration using single-stage filtration, with a filter mesh aperture of 75 μm to remove solid particles with a particle size greater than 75 μm; place the filtered liquid in a centrifuge for centrifugal separation, with a centrifuge rotor speed of 11,000 r / min and a centrifugation time of 10 min. After centrifugation, pour out the upper liquid and collect the bottom precipitate; among them, the oily grinding waste slurry contains 30 g of diamond powder (absolute particle size of 3 - 5 μm), 45 g of vegetable oil, 10 g of mineral oil, and 15 g of zirconia ceramic particles (absolute particle size of 1 - 100 μm);

[0042] (2) Add the precipitate, sulfuric acid solution with a mass fraction of 98%, and analytical pure ammonium sulfate to a polytetrafluoroethylene beaker at a weight ratio of 1:9:3, and heat to 300 - 400 °C, with a holding time of 1 h. Wash the obtained material with water multiple times until the pH of the washing liquid is 6.5 - 7.5. Place the washed solid material in a degreasing furnace for drying, with a drying temperature of 300 °C and a time of 1.5 h to obtain Powder 1. It can be seen that the recovered diamond powder has a complete crystal form, a particle size of 3 - 5 μm, and a relatively high purity; Figure 1 It can be seen that the recovered diamond powder has a complete crystal form, a particle size of 3 - 5 μm, and a relatively high purity;

[0043] Among them, the separating agent includes fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, sodium succinate, sodium citrate, sodium gluconate, sodium carbonate, sodium hydroxide, and potassium hydroxide; based on the total weight of the separating agent, the content of fatty alcohol polyoxyethylene ether is 8% by weight, the content of triethanolamine is 8% by weight, the content of polyoxyethylene glycerol ether is 8% by weight, the content of sodium succinate is 8% by weight, the content of sodium citrate is 8% by weight, the content of sodium gluconate is 5% by weight, the content of sodium carbonate is 15% by weight, the content of sodium hydroxide is 25% by weight, and the content of potassium hydroxide is 15% by weight.

[0044] Example 2

[0045] Use the same separating agent and oily grinding waste slurry as in Example 1;

[0046] (1) Add a separating agent and pure water to 100 g of oily grinding waste slurry, with a weight ratio of addition of 1:0.5:15; then perform dispersion treatment using a mechanical stirrer, with the rotor speed of the stirrer being 500 r / min and the stirring time being 10 min; filter the stirred mixed material, using secondary filtration, with the pore size of the first-stage filter screen being 270 μm, and perform secondary filtration on the liquid obtained from the first-stage filtration, with the pore size of the second-stage filter screen being 75 μm, to remove solid particles with a particle size greater than 75 μm; place the filtered liquid in a centrifuge for centrifugal separation, with the rotor speed of the centrifuge being 1800 r / min and the centrifugation time being 30 min, and after centrifugation, pour off the upper-layer liquid and collect the bottom-layer precipitate;

[0047] (2) Add the precipitate, sulfuric acid solution with a mass fraction of 75%, and analytical pure ammonium sulfate to a polytetrafluoroethylene beaker at a weight ratio of 1:8:4, and heat to 300 - 400 °C, with a holding time of 1.5 h, wash the obtained material with water multiple times until the pH of the washing liquid is 6.5 - 7.5, and place the washed solid material in a drying oven for drying, with the drying temperature being 200 °C and the time being 2 h, to obtain powder 2.

[0048] Example 3

[0049] Use the same separating agent as in Example 1;

[0050] (1) Add a separating agent and pure water to 100 g of diamond polishing waste paste, with a weight ratio of addition of 1:0.8:20; then perform dispersion treatment using an ultrasonic cleaning tank, with the ultrasonic frequency being 40 KHz, the ultrasonic temperature being 70 °C, and the ultrasonic time being 180 min; after the ultrasonic treatment, pump out the paste floating on the upper layer of the mixed solution and filter it, using secondary filtration, with the pore size of the first-stage filter screen being 270 μm, and perform secondary filtration on the liquid obtained from the first-stage filtration, with the pore size of the second-stage filter screen being 75 μm, to remove solid particles with a particle size greater than 75 μm; after the filtered liquid stands for 24 h, pour off the upper-layer liquid and collect the bottom-layer precipitate; among them, the diamond polishing waste paste contains 20 g of diamond powder (absolute particle size of 3 - 5 μm), 50 g of lubricating grease, 5 g of vegetable oil, 5 g of mineral oil, and 20 g of zirconia ceramic particles (absolute particle size of 1 - 100 μm);

[0051] (2) Add the precipitate, sulfuric acid solution with a mass fraction of 98%, and analytical pure ammonium sulfate to a polytetrafluoroethylene beaker at a weight ratio of 1:8:3, and heat to 300 - 400 °C, with a holding time of 1 h, wash the obtained material with water multiple times until the pH of the washing liquid is 6.5 - 7.5, and place the washed solid material in a degreasing furnace for drying, with the drying temperature being 450 °C and the time being 1 h, to obtain powder 3.

[0052] Example 4

[0053] The same separating agent and diamond polishing waste paste as in Example 3 are used;

[0054] (1) Separating agent and pure water are added to 100 g of diamond polishing waste paste, and the weight ratio of addition is 1:0.9:10; then mechanical stirring is carried out for dispersion, the rotor speed of the stirrer is 300 r / min, and the stirring time is 15 min; the mixed material after stirring treatment is filtered, single-stage filtration is adopted, the aperture of the filter screen is 48 μm, and solid particles with a particle size larger than 48 μm are removed; after the filtered liquid is left standing for 36 h, the upper-layer liquid is poured off, and the bottom-layer precipitate is collected;

[0055] (2) The precipitate, sulfuric acid solution with a mass fraction of 50% and analytical pure ammonium sulfate are added into a polytetrafluoroethylene beaker at a weight ratio of 1:10:5, and heated to 300 - 400 °C, and the heat preservation time is 2 h. The obtained material is washed with water many times until the pH of the washing liquid is 6.5 - 7.5. The washed solid material is placed in an oven for drying, the drying temperature is 150 °C, and the time is 3 h to obtain Powder 4.

[0056] Example 5

[0057] The same as Example 1, the only difference is that: in step (1), the weight ratio of oily grinding waste, separating agent and water is 1:0.2:25 to obtain Powder 5.

[0058] Example 6

[0059] The same as Example 1, the only difference is that: in step (2), the weight ratio of the precipitate, sulfuric acid solution and ammonium sulfate is 1:10:1 to obtain Powder 6.

[0060] Example 7

[0061] The same as Example 1, the only difference is that: in step (1), sodium hydroxide in the separating agent is replaced with sodium carbonate of the same weight to obtain Powder 7.

[0062] Example 8

[0063] The same as Example 1, the only difference is that: in step (1), polyoxyethylene fatty alcohol ether, triethanolamine and polyoxyethylene glycerol ether in the separating agent are all replaced with sodium dodecyl sulfate of the same weight to obtain Powder 8.

[0064] Comparative Example 1

[0065] The same as Example 1, the only difference is that: the separating agent in step (1) is replaced with a sodium hydroxide solution of the same weight to obtain Comparative Powder 1.

[0066] Comparative Example 2

[0067] Same as Example 1, except that: step (2) is not adopted, and the precipitate obtained in step (1) is added to pure water and washed repeatedly until the pH is 6.5 - 7.5, and then dried to obtain Comparative Powder 2.

[0068] Comparative Example 3

[0069] Same as Example 1, except that: the organic carboxylate in the separating agent is replaced with sodium hydroxide of the same weight to obtain Comparative Powder 3.

[0070] Comparative Example 4

[0071] Same as Example 1, except that: the sulfuric acid solution in step (2) is replaced with ammonium sulfate of the same weight to obtain Comparative Powder 4.

[0072] Comparative Example 5

[0073] Same as Example 1, except that: the ammonium sulfate in step (2) is replaced with sulfuric acid solution of the same weight to obtain Comparative Powder 5.

[0074] Comparative Example 6

[0075] Same as Example 1, except that: both the sulfuric acid solution and ammonium sulfate in step (2) are replaced with hydrochloric acid solution of the same weight to obtain Comparative Powder 6.

[0076] Test Example

[0077] The powders obtained in the examples and comparative examples were analyzed by scanning electron microscopy - energy dispersive spectroscopy (SEM - EDS). The detection method was as follows: the powders were sputter - coated with gold, placed in a vacuum chamber, and scanned and imaged for composition analysis using a focused ion beam scanning electron microscope - LYRA3XMH produced by TESCAN company to measure the C element content (i.e., diamond content) and Zr element content (i.e., zirconia ceramic particle content). The test standard for element content was: GB / T 17359 - 2012 Microbeam analysis - Quantitative analysis by energy dispersive spectrometry; among which, the element content measured for Powder 1 is shown in Table 1:

[0078] The oil content was measured by thermogravimetric analysis. The specific method was as follows: it was tested using a synchronous thermal analyzer (STA449C) produced by NETZSCH of Germany. The mass of the test material was 3 - 10 mg. The weighed test material was placed in an alumina crucible and tested in an oxygen environment. The gas flow rate of oxygen was fixed at 50 cm 3 / min, the heating rate was set at 10 K / min, and the test temperature range was 25 - 500 °C. The detection basis was: GB / T 13464 - 2008 Thermal analysis test method for the thermal stability of substances;

[0079] Among them, diamond recovery rate % = (mass of diamond in the recovered powder / mass of diamond in the oily grinding waste slurry or diamond polishing waste paste before recovery) × 100%;

[0080] Grease removal rate % = (1 - mass of grease in the recovered powder / mass of grease in the oily grinding waste slurry or diamond polishing waste paste before recovery) × 100%;

[0081] Ceramic particle removal rate % = (1 - mass of ceramic particles in the recovered powder / mass of ceramic particles in the oily grinding waste slurry or diamond polishing waste paste before recovery) × 100%;

[0082] Purity of recovered diamond % = (mass of diamond in the recovered powder / mass of the recovered powder) × 100%.

[0083] Table 1

[0084]

[0085]

[0086] Table 2

[0087]

[0088] From the above data, it can be seen that in Examples 1 to 8, the method of the present disclosure is adopted, and the removal rates of grease and ceramic particles are relatively high, and the diamond recovery rate and purity are relatively high, so that high-purity diamond powder can be effectively recovered; in Comparative Examples 1 to 6, the method of the present disclosure is not adopted, and the obtained powder contains more impurities, and both the diamond recovery rate and purity are relatively low. Therefore, the method provided by Examples 1 to 8 of the present disclosure is more excellent than Comparative Examples 1 to 6.

[0089] By comparing the data of Example 1 and Example 5, it can be seen that when Example 1 adopts the technical solution with a weight ratio of oily grinding waste, separating agent and water of 1: (0.2 - 1): (10 - 20), the grease removal rate is relatively high, and the purity of diamond in the recovered powder is relatively high; by comparing the data of Example 1 and Example 6, it can be seen that when Example 1 adopts the technical solution with a weight ratio of precipitate, sulfuric acid solution and ammonium sulfate of 1: (5 - 10): (3 - 5), the ceramic removal rate is relatively high, and the purity of diamond in the recovered powder is relatively high.

[0090] The preferred embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0091] In addition, it should be noted that, for each of the specific technical features described in the above specific embodiments, they can be combined in any suitable way without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combinations.

[0092] In addition, any combination can also be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for recovering diamond powder from oily grinding waste, characterized in that: The method comprises: (1) mixing oily grinding waste containing diamond powder and ceramic particles, a separating agent and water, filtering the resulting mixture, and then performing solid-liquid separation on the resulting filtrate to collect the precipitate; the oily grinding waste comprises diamond powder, grease and ceramic particles, and the ceramic particles comprise zirconia ceramics; (2) mixing the precipitate, sulfuric acid solution and ammonium sulfate and heating them, and washing and drying the resulting material; the heating temperature is 300-500°C; Wherein, the separating agent comprises a surfactant, an organic carboxylate and an alkaline inorganic substance; The surfactant is one or more of fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, polyethylene glycol, nonylphenol polyoxyethylene ether and polyvinyl pyrrolidone, or the surfactant is sodium lauryl sulfate; The organic carboxylate includes one or more of sodium succinate, sodium citrate, sodium gluconate, sodium acetate, sodium benzoate and sodium formate, and the alkaline inorganic substance includes one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium bicarbonate, calcium hydroxide and barium hydroxide.

2. The method according to claim 1, characterized in that In step (1), the weight ratio of the oily grinding waste, the separating agent and water is 1: (0.2-1): (10-20).

3. The method according to claim 2, characterized in that In step (1), the weight ratio of the oily grinding waste, the separating agent and water is 1: (0.5-1): (15-20).

4. The method according to claim 1, wherein The separating agent comprises fatty alcohol polyoxyethylene ether, triethanolamine, polyoxyethylene glycerol ether, sodium succinate, sodium citrate, sodium gluconate, sodium carbonate, sodium hydroxide and potassium hydroxide; Based on the total weight of the separating agent, the content of the fatty alcohol polyoxyethylene ether is 1 to 10 weight %, the content of the triethanolamine is 2 to 10 weight %, the content of the polyoxyethylene glycerol ether is 2 to 10 weight %, the content of the sodium succinate is 2 to 10 weight %, the content of the sodium citrate is 4 to 16 weight %, the content of the sodium gluconate is 2 to 8 weight %, the content of the sodium carbonate is 2 to 15 weight %, the content of the sodium hydroxide is 10 to 25 weight %, and the content of the potassium hydroxide is 5 to 20 weight %.

5. The method according to claim 1, wherein In step (2), the weight ratio of the precipitate, the sulfuric acid solution and the ammonium sulfate is 1:(5-10):(3-5); based on the total weight of the sulfuric acid solution, the content of the sulfuric acid is 50-98 weight %.

6. The method according to claim 5, characterized in that In step (2), the weight ratio of the precipitate, the sulfuric acid solution and the ammonium sulfate is 1: (7-10): (3-4).

7. The method according to claim 1, characterized in that In step (2), the heating conditions include: the insulation time is 0.5~3h.

8. The method according to claim 7, characterized in that The heating conditions include: a temperature of 300-400° C. and a holding time of 0.5-2 h.

9. The method according to claim 1, characterized in that The method further comprises, before the filtering in step (1), performing a dispersion treatment on the mixture; The dispersion treatment includes mechanical stirring or ultrasonic dispersion. The conditions of the mechanical stirring include: a stirring speed of 100-1000 r / min and a stirring time of 10-30 min; the conditions of the ultrasonic dispersion include: an ultrasonic frequency of 10-100 KHz, an ultrasonic temperature of 20-100° C., and an ultrasonic time of 30-240 min.

10. The method according to claim 1, characterized in that The filtration includes single-stage filtration or multi-stage filtration. The pore size of the filter screen of the single-stage filtration is 25-150 μm, and the pore size of the filter screen of the last stage of the multi-stage filtration is 25-75 μm.

11. The method according to claim 1, wherein In step (1), the solid-liquid separation includes static sedimentation or centrifugal separation, and the static sedimentation time is 12 to 48 hours; the conditions for the centrifugal separation include: centrifuge power of 30 to 50 Hz, speed of 1000 to 12000 r / min, and centrifugal time of 5 to 30 minutes; In step (2), the washing comprises: rinsing the reaction product with pure water once or multiple times until the pH of the washing liquid is 6.5-7.5, and the drying temperature is 150-450° C. and the drying time is 1-3 hours.

12. The method according to claim 1, characterized in that Based on the total weight of the oily grinding waste, the content of the diamond powder is 10-60% by weight, the absolute particle size of the diamond powder is 3-20 μm, and the absolute particle size of the ceramic particles is 1-100 μm.

13. The method according to claim 12, characterized in that Based on the total weight of the oily grinding waste, the content of the diamond powder is 20-30% by weight; the absolute particle size of the diamond powder is 3-5 μm; The oily grinding waste is selected from oily grinding waste slurry and diamond polishing waste paste.

Images