Recovery method of phenolic resin reclaimed sand

Abstract

The invention discloses a phenolic resin reclaimed sand recovery method which comprises the following steps: S1, collecting cast waste sand blocks, crushing the waste sand blocks to enable the diameter of the waste sand blocks to be less than 5mm, and removing casting metal through magnetic separation; s2, the crushed waste sand is vibrated and roasted at the roasting temperature of 200-250 DEG C for 0.5-2 hours, and phenolic resin bonded on the surface of the waste sand is roughly removed; s3, the roasted waste sand is sieved after being cooled, and the sieving aperture is equal to the sum of the casting sand particle size and 0.1-0.2 mm; s4, the sieved waste sand is transferred into water, and the waste sand and the water are dispersed in the water according to the mass ratio of (2.5-3.5): 1 to form turbid liquid; s5, stirring the turbid liquid in the S4, adding laccase, and stirring for 1-3 hours; and S6, stopping stirring, adding new water, after the waste sand is settled, pumping out water and phenolic resin impurities on the upper layer, collecting settled waste sand, and drying the settled waste sand. According to the phenolic resin reclaimed sand obtained through the method, phenolic resin on the surface can be efficiently removed, and breakage in the reclaimed sand recovery production process can be greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of casting, in particular to a method for recovering phenolic resin regenerated sand. Background Art

[0002] 90% of castings are produced by sand casting. Conventional phenolic resin regenerated sand processing methods mostly adopt mechanical grinding and other methods. Although this removes the phenolic resin adhering to the surface of the waste sand, it is also inevitable that the particle size of the waste sand is unnecessarily polished, resulting in a reduction in the particle size of the waste sand and reducing the recycling rate of the waste sand.

[0003] The Chinese invention patent application with publication number CN117840382A discloses an energy-saving regeneration method for foundry waste sand. The regenerated sand obtained by this method has better sphericity, high demolding rate, and restores the original morphology of the gravel, but does not consider the problem of particle size reduction of the regenerated sand during the friction process. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that mechanical grinding in the existing phenolic resin regenerated sand recovery technology leads to a reduction in the particle size of the regenerated sand, resulting in a decrease in the recovery rate.

[0005] The technical solution provided by the present invention is as follows: a method for recovering phenolic resin regenerated sand, comprising the following steps: S1, collecting the waste sand blocks after casting and crushing them until the diameter of the waste sand blocks is less than 5 mm, and magnetic separation to remove the casting metal; S2, shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is preferably 200-250° C., more preferably 230-250° C., the roasting time is 0.5-2 hours, and the phenolic resin bonded to the surface of the waste sand is roughly removed; S3, waiting for the waste sand after roasting to cool down and then sieving, the sieve aperture is the casting sand particle size + 0.1~0.2 mm; S4, transferring the sieved waste sand into water, and dispersing the waste sand and water into a suspension in the water according to a mass ratio of preferably 2.5 to 3.5:1, more preferably 3 to 3.5:1; S5, stirring the suspension described in S4, and adding laccase, the mass ratio of waste sand to laccase is preferably 1000-5000:1, more preferably 1000-2000:1, and the stirring time is 1-3 hours; S6, stop stirring, add new water, and after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it.

[0006] A further embodiment also includes: the oscillation method in S2 is mechanical oscillation and / or sonic oscillation, and the oscillation process is carried out in a sealed environment.

[0007] A further embodiment also includes: abrasive is added to the water in S4, and the mass ratio of abrasive to waste sand is preferably 0.1-0.2:1, and the abrasive is at least one of zircon, brown corundum, and new sand for casting.

[0008] A further embodiment also includes: the stirring in S5, with a stirring rate of 500-800 rad / min.

[0009] A further embodiment also includes: adding an acid-base regulator to the suspension of S4 to adjust the pH to 6-7, and adding a thickener.

[0010] A further embodiment also includes: adding an acid-base regulator and a thickener to the suspension of S4, extracting the wastewater formed by S6, adjusting the pH of the wastewater to neutral, and then purifying the wastewater for recycling.

[0011] A further implementation scheme also includes: after the stirring in S6 is completed, air is injected into the suspension formed in S6, bubble stirring is intermittently adopted, and the suspension is allowed to stand to transfer impurities with lower density such as phenolic resin particles to the upper layer of the liquid surface.

[0012] The advantages and beneficial effects of the present invention are: 1. The phenolic resin sand is placed in water and stirred with abrasive to break the surface phenolic resin. The recovery method of laccase decomposition avoids mechanical grinding that will reduce the particle size of the regenerated sand, thereby improving the recovery rate and regeneration effect of the regenerated sand.

[0013] 2. Use water as the medium to separate and remove the regenerated sand and the phenolic resin on its surface according to density. This is simple and efficient, and avoids the large amount of smoke and dust generated by mechanical grinding.

[0014] 3. By adjusting various parameters and additives for the recovery of regenerated sand, the morphology of the regenerated sand is optimized, the technical problem of the difficulty in recycling regenerated sand multiple times is solved, and the pollution generated is less and easier to handle. DETAILED DESCRIPTION

[0015] The present invention provides a phenolic resin regenerated sand recovery method, which comprises the following steps: S1, collecting the waste sand blocks after casting and crushing them until the diameter of the waste sand blocks is less than 5 mm, and magnetic separation to remove the casting metal; S2, shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is 200-250° C., the roasting time is 0.5-2 hours, and the phenolic resin bonded to the surface of the waste sand is roughly removed; S3, waiting for the waste sand after roasting to cool down and then sieving, the sieve aperture is the casting sand particle size + 0.1~0.2 mm; S4, transferring the sieved waste sand into water, and dispersing the waste sand and water into a suspension in the water at a mass ratio of 2.5-3.5:1; S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is preferably 100-500:1, and the stirring time is 1-3 hours; S6, stop stirring, add new water, and after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it.

[0016] During the casting process, the molten metal may break through the phenolic resin film and flow into the surface and inside of the molding sand, which will form residual material on the surface of the casting, which is not only not conducive to metal casting and molding, but also affects the recovery of regenerated sand. Different methods should be selected for different metals to remove them from the sand before recovery. Considering that iron is the main casting material, the present invention preferably uses magnetic separation to remove the cast metal iron. It is known that magnetic separation can also remove metals such as cobalt and nickel and their alloys.

[0017] There are combustible materials such as phenolic resin film and coal powder in phenolic resin sand, which can be gasified and burned at high temperature, but the binder such as montmorillonite coated on the surface of sand grains will lose structure water at 600-730 ℃ and burn into a hard and water-insoluble ceramic-like hard block, which can neither be washed off by water nor be removed mechanically. The present invention adopts the mode of vibration to produce a certain gap between the phenolic resin bonded on the surface of waste sand and the waste sand, and even makes the waste sand and phenolic resin initially separated. While vibrating, roasting can also make the phenolic resin melt, and certain flow occurs, thereby strengthening the technical effect of the above-mentioned initial separation. Implementing in a closed environment is to reduce noise on the one hand, and to reduce heat convection and improve thermal efficiency on the other hand.

[0018] The sieved waste sand is transferred to water to form a suspension in the water to facilitate the subsequent stirring and removal of phenolic resin. Specifically, the sand in the suspension is better dispersed, and the particle size after stirring and grinding is more uniform. Moreover, since water is used as a medium, the erosion of the sand surface due to the stirring process can be effectively avoided by reasonably adjusting the stirring rate and stirring time, thereby preventing the reduction of the sand particle size. At the same time, water as a medium can also make the lighter phenolic resin float to the water surface after stopping stirring, and it can be separated by simple suction. In addition, the smoke generated by grinding directly enters the water, which effectively avoids the smoke problem. The settled waste sand will also show a certain particle size distribution effect. When used, the regenerated sand with too small particle size in the upper layer can be directly discarded, thereby reducing the cost of recycling the regenerated sand.

[0019] Adding abrasives, thickeners, etc. to water is to improve the grinding efficiency and the technical effect achieved by grinding. Preferably, the abrasive can be zircon, brown corundum, new sand for casting, etc., and the preferred particle size is close to the new sand for casting. Abrasives with larger particle sizes are subject to greater resistance during stirring, and have a relative speed with the waste sand during stirring, and relative motion occurs, which can increase the probability of friction between the abrasive and the surface of the waste sand, but will also affect subsequent recycling work, and even require separate separation of the abrasive for use in regenerated sand; choosing to use zircon, brown corundum, new sand for casting and other materials allows the selected abrasive to directly enter the regenerated sand after the recycling work is completed, avoiding the need to separate the waste sand and the abrasive.

[0020] The purpose of adding thickeners is to increase the viscosity of water. The waste sand in high-viscosity water has greater friction, and the effect of separating the waste sand bonded to the phenolic resin is better. However, it should also be noted that water with too high viscosity will corrode the sand surface of the waste sand, thereby affecting the particle size of the waste sand. In the embodiments of the present invention, cellulose thickeners are used as thickeners. It should not be considered that only cellulose thickeners can achieve the above functions. It can be understood that water-soluble thickeners including cellulose thickeners can achieve technical effects; adding acid-base regulators to water can increase the solubility of cellulose thickeners. The preferred pH for increasing the solubility of cellulose thickeners is 1 or 13, but the strong acid and strong alkaline environment is not conducive to the technical effect of adding laccase in the subsequent process of the present invention. Therefore, it is sufficient to adjust the pH to weak acid to weak alkaline. Considering the alkalinity of the phenolic resin itself, and the phenolic resin in the magnetic separation stage, there is also Na + and K + It is not removed. The acid-base regulator mainly refers to the acid regulator. The wastewater with added acid-base regulator and thickener needs to be specially purified before it can be used again for suspension preparation. The thickener can be treated by heating to increase solubility, cooling and precipitation, etc. without complete purification. However, the large amount of salt produced by acid-base neutralization will accumulate and crystallize during repeated use, and needs to be purified and separated regularly.

[0021] Laccase is a copper-containing polyphenol oxidase that can catalyze the oxidation of substrates through electron transfer between copper ions at the active site and substrates. For phenolic resins, laccase can oxidize phenolic lignin structures to help decompose phenolic resins. Specifically, laccase can oxidize phenolic hydroxyl groups in phenolic resins to form free radicals, which further polymerize or react with other functional groups in the resin, resulting in the breakage of resin chains and a reduction in molecular weight, thereby achieving degradation of phenolic resins. The operating temperature of laccase is 30 to 50 ° C, which can be achieved at room temperature, and since stirring will generate a certain amount of heat, there is no need to heat it specifically, and the pH requirement is weakly acidic to weakly alkaline. In addition, the laccase selected by the present invention is purchased from Nanjing Jinke Biotechnology Co., Ltd., item number JK-052. The acid-base regulator is preferably acetic acid.

[0022] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0023] Embodiment 1 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 5mm, and use magnetic separation to roughly remove the casting metal; S2, mechanically shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is 250° C., and the roasting time is 0.5 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 3.5:1; adding zircon as an abrasive, and the mass ratio of the abrasive to the waste sand is 0.1:1.

[0024] S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 1000:1, the stirring time is 1 hour, adding acid-base regulator to adjust the pH to 6, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 800 rad / min.

[0025] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0026] Embodiment 2 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 5 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to sonic vibration and roasting it while vibrating, the roasting temperature is 230° C., and the roasting time is 1 hour; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 3:1; adding brown corundum as an abrasive, and the mass ratio of the abrasive to the waste sand is 0.1:1.

[0027] S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 2000:1, the stirring time is 2 hours, adding acid-base regulator to adjust the pH to 6.5, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 800 rad / min.

[0028] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0029] Embodiment 3 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 5 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to mechanical and sonic vibration, and roasting it while vibrating, the roasting temperature is 200° C., and the roasting time is 2 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.7 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 2.5:1, adding new sand for casting as abrasive, and the mass ratio of abrasive to waste sand is 0.2:1.

[0030] S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 5000:1, the stirring time is 3 hours, adding acid-base regulator to adjust the pH to 7, stirring to make the laccase evenly distributed, and the stirring rate is 800 rad / min.

[0031] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0032] Embodiment 4 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 4 mm, and use magnetic separation to roughly remove the casting metal; S2, mechanically shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is 250° C., and the roasting time is 0.5 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 3.5:1, adding zircon and brown corundum (1:1) as abrasives, and the mass ratio of abrasives to waste sand is 0.2:1.

[0033] S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 1000:1, the stirring time is 1 hour, adding acid-base regulator to adjust the pH to 6, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 600 rad / min.

[0034] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0035] Embodiment 5 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 4 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to sonic vibration and roasting it while vibrating, the roasting temperature is 230° C., and the roasting time is 1 hour; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 3:1, adding zircon and new sand for casting (1:1) as abrasives, and the mass ratio of abrasives to waste sand is 0.2:1.

[0036] S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 2000:1, the stirring time is 2 hours, adding acid-base regulator to adjust the pH to 6.5, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 600 rad / min.

[0037] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0038] Embodiment 6 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 4 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to mechanical and sonic vibration, and roasting it while vibrating, the roasting temperature is 200° C., and the roasting time is 2 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.7 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 2.5:1, adding brown corundum and new sand for casting (1:1) as abrasives, and the mass ratio of abrasives to waste sand is 0.2:1.

[0039] S5, stirring the suspension described in S4, and adding laccase, the mass ratio of waste sand to laccase is 5000:1, stirring for 3 hours, adding acid-base regulator to adjust the pH to 7, stirring to make the laccase evenly distributed, and the stirring rate is 600 rad / min.

[0040] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0041] Embodiment 7 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 3 mm, and use magnetic separation to roughly remove the casting metal; S2, mechanically shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is 250° C., and the roasting time is 0.5 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 3.5:1, adding new sand for casting (1:1) as abrasive, and the mass ratio of abrasive to waste sand is 0.2:1.

[0042] S5, stirring the suspension described in S4, and adding laccase, the mass ratio of waste sand to laccase is 1000:1, the stirring time is 1 hour, adding acid-base regulator to adjust the pH to 6, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 500 rad / min.

[0043] S6, stop stirring, add new water, inject air into the suspension, intermittently stir with bubbles, let it stand, transfer the impurities with smaller density such as phenolic resin particles to the upper layer of the liquid surface, after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the wastewater, add an acid-base regulator to the wastewater to adjust the pH to neutral, distill the wastewater, and remove the salt in the wastewater.

[0044] Embodiment 8 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 3 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to sonic vibration and roasting it while vibrating, the roasting temperature is 230° C., and the roasting time is 1 hour; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water in the water in a mass ratio of 3:1 into a suspension, adding new sand for casting (1:1) as abrasive, and the mass ratio of abrasive to waste sand is 0.2:1; S5, stirring the suspension described in S4, and adding laccase, the mass ratio of waste sand to laccase is 2000:1, the stirring time is 2 hours, adding acid-base regulator to adjust the pH to 6.5, and adding 1 kg of cellulose thickener, stirring to dissolve the cellulose thickener and evenly distribute the laccase, the stirring rate is 500 rad / min.

[0045] S6, stop stirring, add new water, inject air into the suspension, intermittently stir with bubbles, let it stand, transfer the impurities with smaller density such as phenolic resin particles to the upper layer of the liquid surface, after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the wastewater, add an acid-base regulator to the wastewater to adjust the pH to neutral, distill the wastewater, and remove the salt in the wastewater.

[0046] Embodiment 9 A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 3 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to mechanical and sonic vibration, and roasting it while vibrating, the roasting temperature is 200° C., and the roasting time is 2 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.7 mm; S4, transferring the sieved waste sand into water, dispersing the waste sand and water into a suspension in the water at a mass ratio of 2.5:1, adding new sand for casting (1:1) as abrasive, and the mass ratio of abrasive to waste sand is 0.2:1.

[0047] S5, stirring the suspension described in S4, and adding laccase, the mass ratio of waste sand to laccase is 5000:1, the stirring time is 3 hours, adding acid-base regulator to adjust the pH to 7, stirring to make the laccase evenly distributed, and the stirring rate is 500 rad / min.

[0048] S6, stop stirring, add new water, inject air into the suspension, intermittently stir with bubbles, let it stand, transfer the impurities with smaller density such as phenolic resin particles to the upper layer of the liquid surface, after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the wastewater, add an acid-base regulator to the wastewater to adjust the pH to neutral, distill the wastewater, and remove the salt in the wastewater.

[0049] Comparative Example A phenolic resin regenerated sand recovery method comprises the following steps: S1, collect 100kg of waste sand blocks after casting and crush them until the diameter of the waste sand blocks is less than 5 mm, and use magnetic separation to roughly remove the casting metal; S2, subjecting the crushed waste sand to mechanical and sonic vibration, and roasting it while vibrating, the roasting temperature is 250° C., and the roasting time is 2 hours; S3, waiting for the calcined waste sand to cool down and then sieving it, the sieve aperture is 0.8 mm; S4, transferring the sieved waste sand into water, and dispersing the waste sand and water into a suspension in the water at a mass ratio of 3.5:1; S5, stirring the suspension described in S4 at a stirring rate of 800 rad / min for 3 hours.

[0050] S6, stop stirring, add new water, wait for the waste sand to settle, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it, collect the waste water, add an acid-base regulator to the waste water to adjust the pH to neutral, distill the waste water, and remove the salt in the waste water.

[0051] Technical effect: The original particle size distribution of the waste sand in the above embodiments and comparative examples is 0.425~0.6mm.

[0052] When calculating the following data, the mass of the abrasive is excluded from the calculation process. For example, when analyzing the data in Example 1, the mass of the initial waste sand is 100 kg. Since 10 kg of abrasive is added to the collected regenerated sand, phenolic resin M kg is also removed. When calculating the mass of the regenerated sand, only 100-M kg is calculated, excluding the mass of the abrasive. The regenerated sand that does not pass through the 0.425 mesh is qualified sand, and its mass is recorded as m.

[0053] The particle size mass percentage A is calculated as follows: A=m / (100-M)*100% The acid consumption value and loss on ignition of the regenerated sand of each embodiment of the present invention and the comparative example are tested according to the standard of GB / T8583-2008. In addition, the acid consumption value does not include the acid-base regulator used for adjusting the pH in step S5.

[0054] 0.425~0.6mm particle size mass percentage Mass percentage of particle size 0.425~0.6mm after three regenerations Acid consumption value (mL / 50g) Loss on ignition percentage Embodiment 1 98.2 92.6 3.6 1.14 Embodiment 2 95.7 92.9 4.1 1.50 Embodiment 3 96.0 93.5 3.8 1.27 Embodiment 4 98.4 96.2 3.6 1.18 Embodiment 5 94.3 92.1 4.2 1.47 Embodiment 6 97.6 94.8 3.8 1.31 Embodiment 7 98.2 96.7 3.7 1.13 Embodiment 8 96.5 94.0 4.2 1.48 Embodiment 9 96.7 93.8 3.8 1.32 Comparative Example 62.3 57.6 5.4 3.06 The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering phenolic resin regenerated sand: characterized in that: The following steps are involved: S1, collecting the waste sand blocks after casting and crushing them until the diameter of the waste sand blocks is less than 5 mm, and magnetic separation to remove the casting metal; S2, shaking the crushed waste sand, and roasting it while shaking, the roasting temperature is 200-250° C., the roasting time is 0.5-2 hours, and the phenolic resin bonded to the surface of the waste sand is roughly removed; S3, waiting for the waste sand after roasting to cool down and then sieving, the sieve aperture is the casting sand particle size + 0.1~0.2 mm; S4, transferring the sieved waste sand into water, and dispersing the waste sand and water into a suspension in the water at a mass ratio of 2.5-3.5:1; S5, stirring the suspension described in S4 and adding laccase, the mass ratio of waste sand to laccase is 1000-5000:1, and the stirring time is 1-3 hours; S6, stop stirring, add new water, and after the waste sand settles, extract the water and the upper phenolic resin impurities, collect the settled waste sand and dry it.

2. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: The oscillation mode in S2 is mechanical oscillation and / or sonic oscillation, and the oscillation process is performed in a sealed environment.

3. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: Abrasive is also added to the water in S4, the mass ratio of abrasive to waste sand is 0.1-0.2:1, and the abrasive is at least one of brown corundum, zircon, and new sand for casting.

4. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: An acid-base regulator is also added to the suspension of S4 to adjust the pH to 6-7, and a thickener is also added.

5. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: The stirring rate of S5 is 500-800 rad / min.

6. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: A thickener is also added to the suspension formed by S5.

7. The phenolic resin regenerated sand recovery method according to claim 4, characterized in that: The wastewater formed in S6 is pumped out, the pH is adjusted to neutral, and then the wastewater is purified and recycled.

8. The phenolic resin regenerated sand recovery method according to claim 1, characterized in that: The stirring method of S5 and S6 is mechanical stirring. After S6 stops stirring, air is intermittently injected into the suspension formed by sand-water, and the suspension is allowed to stand again to transfer the phenolic resin settled in the waste sand to the upper liquid surface of the suspension.