Casting clay waste sand regeneration method

Abstract

The invention relates to the field of casting waste sand treatment, in particular to a casting waste sand regeneration method. The regeneration method comprises the following steps: (1) carrying out crushing and magnetic separation on cast iron clay waste sand; (2) preparing a mixed auxiliary agent solution: preparing K2CO3, NaHCO3 and an oxidizing agent into the mixed auxiliary agent solution; (3) mixing the cast iron clay waste sand subjected to magnetic separation in the step (1) with the mixed additive solution prepared in the step (2), stirring and standing; (4) low-temperature roasting is conducted, specifically, the cast iron clay waste sand treated in the step (3) is subjected to low-temperature roasting, the low-temperature roasting temperature is 500 DEG C, and the time is 30-60 minutes; and (5) the cast iron clay waste sand treated in the step (4) is ground and screened, and reclaimed sand is obtained. According to the regeneration method, under short-time low-temperature roasting, the pulverized coal wrapping the casting waste sand is still fully decomposed, and high-quality regenerated sand is obtained. Therefore, the casting waste sand regeneration cost and the equipment investment are greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of casting waste sand treatment, and particularly relates to a casting clay waste sand regeneration method. BACKGROUND

[0002] In the casting industry, the clay sand molding process is widely used in the production of various castings due to its relatively low cost, simple operation and strong adaptability. A large amount of casting clay waste sand is discharged, which contains a large amount of impurities such as sand falling off during casting, metal oxide skin, coal powder and high-temperature failure clay binder. These impurities will cause the performance of waste sand to decrease significantly and cannot be used again. Direct disposal or simple landfill methods are often used for treatment. Not only will it pollute the soil environment, but also will cause waste of resources. The recycling of casting clay sand has become an urgent need for the development of the industry.

[0003] At present, the more advanced regeneration method is "high-temperature roasting + mechanical grinding". The high-temperature roasting method is used to remove the coal powder and organic matter in the casting clay waste sand, and to form the voids left after the decomposition of the coal powder on the surface of the sand particles. The strength of the clay layer, especially the oolitic layer, is greatly reduced, and the surface clay can be easily removed by subsequent mechanical grinding, thereby obtaining regenerated sand.

[0004] In order to realize 100% of the regenerated sand for subsequent core production process, the coal powder and clay on the surface of the casting clay waste sand must be completely removed. However, high-temperature roasting has significant drawbacks. Because the coal powder in the waste sand is tightly wrapped by clay, it is difficult to fully contact oxygen during roasting, making it difficult to decompose the coal powder. At present, when using a vertical roasting furnace, in order to ensure the full decomposition of the coal powder, the roasting temperature must be set to a relatively high range of 670-690°C, and the roasting time must be as long as 4 hours or more. On the one hand, maintaining a high temperature for a long time and a long roasting period greatly increases energy consumption and significantly increases production costs. On the other hand, it puts extremely high requirements on the performance of the equipment. A production line of only 5T / h requires an investment of about 10 million yuan in equipment, and the factory building must also meet strict standards to adapt to the process requirements of high temperature and long time operation. This not only causes a huge initial capital investment, but also has low overall production efficiency, greatly hindering the widespread application of this technology in the casting industry, making the cost of clay sand regeneration high, and becoming a major obstacle to the development of the industry.

[0005] Therefore, it is an urgent problem to be solved in the field to develop a low-cost and high-recovery-rate casting clay waste sand regeneration method. SUMMARY

[0006] In order to solve the above technical problems, the application provides a casting clay waste sand regeneration method, which can effectively reduce the regeneration cost and realize 100% recovery rate of waste sand.

[0007] The application adopts the following technical scheme:

[0008] A casting clay waste sand regeneration method, characterized in that the method comprises the following steps:

[0009] (1) crushing and magnetic separation of cast iron clay waste sand;

[0010] (2) preparation of a mixed additive solution: mixing K2CO3, NaHCO3 and an oxidizing agent to prepare a mixed additive powder, and preparing a mixed additive solution by mixing the mixed additive powder with water;

[0011] (3) mixing the cast iron clay waste sand after the magnetic separation in step (1) with the mixed additive solution prepared in step (2), stirring, and standing;

[0012] (4) low-temperature roasting: low-temperature roasting the cast iron clay waste sand after the treatment in step (3), and the low-temperature roasting temperature is 500 DEG C, and the time is 30-60 minutes;

[0013] (5) grinding and screening the cast iron clay waste sand after the treatment in step (4) to obtain regenerated sand.

[0014] Further, in step (2), K2CO3, NaHCO3 and the oxidizing agent are mixed in a mass ratio of (2-3):1:1.

[0015] After the cast iron clay waste sand and the mixed additive are fully mixed and stand in step (3), in the low-temperature roasting process, the K2CO3 in the mixed additive is decomposed into K2O and CO2, the generated K2O further reacts with carbon in the coal powder or water vapor in the environment to release K + The carbon structure in the coal powder has a layered structure, and K + is a small-radius alkali metal ion, which can diffuse into the carbon interlayer under heating to form a potassium-carbon interlayer compound, thereby destroying the binding force between the carbon interlayers and reducing the C-C bond strength, thereby reducing the pyrolysis activity. At the same time, the released CO2 can make the clay layer loose, thereby reducing the binding force between the clay and the sand body.

[0016] At the same time, NaHCO3 is decomposed under low-temperature heating to release CO2 and water vapor, thereby forming micro-bubbles in the clay layer, making the clay layer loose, and opening a contact channel for the coal powder and external oxygen; the subsequent product when heated, reacts with the aluminosilicate in the clay, , and the hydrolysis product attack the hydroxyl groups in clay minerals, thereby breaking the Al-O-Si bonds of the clay layer, and the product is sodium feldspar ) structure is loose, further reducing the strength of the clay layer, making it easier for subsequent mechanical grinding.

[0017] At the same time, the oxidizing agent in the mixed additive decomposes step by step during the calcination process, continuously releasing O2, which directly participates in the oxidation of the coal powder, reducing the temperature required for calcination; the released free radical initiator can accelerate the pyrolysis of the coal powder through a chain reaction.

[0018] In the regeneration process of foundry clay waste sand, and the synergistic effect of the oxidizing agent achieves efficient decarburization and clay structure destruction through multi-dimensional mechanisms: At 150-200°C, it decomposes to produce , which peels off the interlayer structure of the clay through gas expansion and water vapor plasticization, providing a channel for subsequent reactions; the oxidizing agent gradually decomposes to release and free radical initiators, which oxidize the exposed coal powder and catalyze its pyrolysis, and the generated free radical initiators react with clay to break the Al-O-Si bonds; At >400°C, it decomposes into , which inserts into the carbon layer of the residual coal powder to weaken the C-C bonds, and simultaneously accelerates the fracture of the clay lattice in coordination with the oxidizing agent. Through temperature response complementation, oxidation-reduction cycle linkage, ion exchange, and gas expansion superposition effects, the three greatly reduce the temperature and time required for calcination while ensuring carbon powder removal and clay peeling.

[0019] Further, the oxidizing agent is at least one of sodium chlorate, sodium chlorite, and potassium nitrate. Preferably, the oxidizing agent is potassium nitrate.

[0020] Further, in step (2), the mass ratio of the mixed additive powder to water is (20-30):(80-90).

[0021] Further, in step (3), the mass ratio of the mixed additive solution to the foundry clay waste sand is (2-3):100.

[0022] Further, the standing time is 3-4 hours.

[0023] Further, in step (1), a jaw crusher, hammer crusher, or impact crusher is used to crush the foundry clay waste sand, and the crushed fine sand with a particle size of less than 5 mm is obtained.

[0024] Further, the foundry clay waste sand after magnetic separation is subjected to a grading vibrating screen, and the crushed clay waste sand with a size of 60-100 mesh is screened out.

[0025] Further, in step (5), the grinding uses a ball mill or a vibration mill, and the grinding is performed for 0.5-1 hour.

[0026] Further, in step (5), the screening uses a vibration screen or a drum screen, and the particle size of the regenerated sand after the screening is 40-140 mesh.

[0027] Further, in step (4), the roasting uses a horizontal roaster or a through-type roaster.

[0028] Advantages of the present application:

[0029] The present application has the advantages of simple process, low energy consumption, and strong operability. By adding a mixed additive, the decomposition temperature of the coal powder is reduced to below 500 DEG C through the catalysis and oxidation of the additive, the Al-O-Si bond of the clay layer is broken through the cracking of the additive to reduce the strength of the clay layer, and the density of the clay is destroyed through the gas evolution of the additive to make the coal powder more easily contact with oxygen, so that the decomposition speed is reduced to within 30 minutes. Thus, the recycling efficiency and cost of the casting clay waste sand are greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flow chart for regenerating the casting clay waste sand. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0032] Unless otherwise specified, the materials used in the embodiments of the present application can be obtained through commercial channels or prepared according to conventional methods well known to those skilled in the art.

[0033] The present application provides a method for regenerating casting clay waste sand, which comprises the following steps: Figure 1 The method comprises the following steps:

[0034] (1) crushing and magnetic separation of the cast iron clay waste sand;

[0035] (2) preparing a mixed additive solution: mixing K2CO3, NaHCO3 and an oxidizing agent to prepare a mixed additive powder, and preparing a mixed additive solution by mixing the mixed additive powder with water;

[0036] (3) mixing the cast iron clay waste sand after the magnetic separation in step (1) with the mixed additive solution prepared in step (2), stirring, and standing;

[0037] (4) low-temperature roasting: the cast iron clay waste sand treated in the step (3) is low-temperature roasted at a temperature of 500 DEG C for 30-60 minutes;

[0038] (5) the cast iron clay waste sand treated in the step (4) is ground and screened to obtain regenerated sand.

[0039] In order to more clearly illustrate the technical solutions and advantages of the present application, the present application will be further explained and described in conjunction with examples and comparative examples.

[0040] Example 1

[0041] A cast clay waste sand regeneration method comprises the following steps:

[0042] (1) the cast clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, the metal substances in the waste sand are removed by a magnetic separator, and the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0043] (2) a mixed additive solution is prepared: 20 g of K2CO3, 10 g of NaHCO3 and 10 g of KNO3 powder are mixed, 160 g of water is added to the mixed powder, and the mixed additive solution is prepared by stirring;

[0044] (3) 4 g of the mixed additive solution prepared in the step (2) is added to 200 g of the waste sand treated in the step (1), stirred uniformly, and left to stand for 5 hours;

[0045] (4) low-temperature roasting: the cast clay waste sand treated in the step (3) is placed in a horizontal roasting furnace and roasted at 500 DEG C for 30 minutes, and cooled to room temperature;

[0046] (5) the cast iron clay waste sand treated in the step (4) is ground in a ball mill for 0.5 hours, and then screened by a vibrating screen to recover the regenerated sand with a particle size of 40-140.

[0047] Example 2

[0048] A cast clay waste sand regeneration method comprises the following steps:

[0049] (1) the cast clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, the metal substances in the waste sand are removed by a magnetic separator, and the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0050] (2) Preparation of mixed additive solution: 30 g of K2CO3, 10 g of NaHCO3 and 10 g of sodium chlorate powder are mixed, 200 g of water is added to the mixed powder, stirred, and a mixed additive solution is prepared;

[0051] (3) 6 g of the mixed additive solution prepared in step (2) is added to 200 g of the waste sand treated in step (1), stirred uniformly, and left to stand for 4 hours;

[0052] (4) Low-temperature roasting: the foundry clay waste sand treated in step (3) is placed in a horizontal roasting furnace and roasted at 500 DEG C for 60 minutes, and cooled to room temperature;

[0053] (5) The foundry clay waste sand treated in step (4) is ground in a ball mill for 1 hour, and then screened through a vibrating screen to recover the regenerated sand with a particle size of 40-140 mesh.

[0054] Example 3

[0055] A foundry clay waste sand regeneration method, comprising the following steps:

[0056] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, the metal substances in the waste sand are removed by a magnetic separator, and the waste sand with a particle size of 40-140 mesh is screened out by a grading vibrating screen;

[0057] (2) Preparation of mixed additive solution: 25 g of K2CO3, 10 g of NaHCO3 and 10 g of sodium chlorite powder are mixed, 135 g of water is added to the mixed powder, stirred, and a mixed additive solution is prepared;

[0058] (3) 5 g of the mixed additive solution prepared in step (2) is added to 200 g of the waste sand treated in step (1), stirred uniformly, and left to stand for 4 hours;

[0059] (4) Low-temperature roasting: the foundry clay waste sand treated in step (3) is placed in a horizontal roasting furnace and roasted at 500 DEG C for 30 minutes, and cooled to room temperature;

[0060] (5) The foundry clay waste sand treated in step (4) is ground in a ball mill for 0.5 hours, and then screened through a vibrating screen to recover the regenerated sand with a particle size of 40-140 mesh.

[0061] Example 4

[0062] A foundry clay waste sand regeneration method, comprising the following steps:

[0063] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, and then the metal substances in the waste sand are removed by a magnetic separator, and then the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0064] (2) Preparation of mixed additive solution: 10 g of K2CO3, 10 g of NaHCO3 and 10 g of KNO3 powder are mixed, 120 g of water is added to the mixed powder, and stirring is performed to prepare a mixed additive solution;

[0065] (3) 5 g of the mixed additive solution prepared in step (2) is added to 200 g of the waste sand treated in step (1), and stirring is performed to obtain a uniform mixture, and then the mixture is left to stand for 4 hours;

[0066] (4) Low-temperature roasting: the foundry clay waste sand treated in step (3) is placed in a horizontal roasting furnace and roasted at 500°C for 30 minutes, and then cooled to room temperature;

[0067] (5) The foundry clay waste sand treated in step (4) is ground in a ball mill for 0.5 hours, and then the regenerated sand with a particle size of 40-140 is recovered by a vibrating screen.

[0068] Comparative Example 1

[0069] A method for regenerating foundry clay waste sand, comprising the following steps:

[0070] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, and then the metal substances in the waste sand are removed by a magnetic separator, and then the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0071] (2) Low-temperature roasting: the foundry clay waste sand treated in step (1) is placed in a horizontal roasting furnace and roasted at 500°C for 30 minutes, and then cooled to room temperature;

[0072] (3) The foundry clay waste sand treated in step (2) is ground in a ball mill for 0.5 hours, and then the regenerated sand with a particle size of 40-140 is recovered by a vibrating screen.

[0073] Comparative Example 2

[0074] A method for regenerating foundry clay waste sand, comprising the following steps:

[0075] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, and then the metal substances in the waste sand are removed by a magnetic separator, and then the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0076] (2) Preparation of mixed additive solution: take 45g K2CO3 powder, add 135g water to it, stir, and prepare a mixed additive solution;

[0077] (3) Take 5g of the mixed additive solution prepared in step (2) and add it to 200g of the waste sand treated in step (1), stir uniformly, and stand for 4 hours;

[0078] (4) Low-temperature roasting: place the foundry clay waste sand treated in step (3) in a horizontal roasting furnace and roast at 500°C for 30 minutes, and cool to room temperature;

[0079] (5) Grind the foundry clay waste sand treated in step (4) in a ball mill for 0.5 hours, and then screen through a vibrating screen to recover the regenerated sand with a particle size of 40-140 mesh.

[0080] Comparative Example 3

[0081] A method for regenerating foundry clay waste sand, comprising the following steps:

[0082] (1) Crush the foundry clay waste sand in a jaw crusher to obtain crushed fine sand with a particle size of less than 5mm, remove metal substances in the waste sand by magnetic separation, and then screen out waste sand with a particle size of 40-140 mesh through a grading vibrating screen;

[0083] (2) Preparation of mixed additive solution: take 45g NaHCO3 powder, add 135g water to it, stir, and prepare a mixed additive solution;

[0084] (3) Take 5g of the mixed additive solution prepared in step (2) and add it to 200g of the waste sand treated in step (1), stir uniformly, and stand for 4 hours;

[0085] (4) Low-temperature roasting: place the foundry clay waste sand treated in step (3) in a horizontal roasting furnace and roast at 500°C for 30 minutes, and cool to room temperature;

[0086] (5) Grind the foundry clay waste sand treated in step (4) in a ball mill for 0.5 hours, and then screen through a vibrating screen to recover the regenerated sand with a particle size of 40-140 mesh.

[0087] Comparative Example 4

[0088] A method for regenerating foundry clay waste sand, comprising the following steps:

[0089] (1) Crush the foundry clay waste sand in a jaw crusher to obtain crushed fine sand with a particle size of less than 5mm, remove metal substances in the waste sand by magnetic separation, and then screen out waste sand with a particle size of 40-140 mesh through a grading vibrating screen;

[0090] (2) Preparation of mixed additive solution: take 45g KNO3 powder, add 135g water to it, stir, and prepare a mixed additive solution;

[0091] (3) Take 5g of the mixed additive solution prepared in step (2) and add it to 200g of the waste molding sand treated in step (1), stir uniformly, and stand for 4 hours;

[0092] (4) Low-temperature roasting: place the waste molding clay sand treated in step (3) in a horizontal roasting furnace and roast at 500°C for 30 minutes, and cool to room temperature;

[0093] (5) Grind the cast iron clay waste sand treated in step (4) in a ball mill for 0.5 hours, and then pass it through a vibrating screen to screen and recover the regenerated sand with a particle size of 40-140 mesh.

[0094] Comparative Example 5

[0095] A method for regenerating waste molding clay sand, comprising the following steps:

[0096] (1) Crush the waste molding clay sand in a jaw crusher to obtain crushed fine sand with a particle size of less than 5mm, remove metal substances in the waste sand by magnetic separation, and then screen out waste sand with a particle size of 40-140 mesh through a grading vibrating screen;

[0097] (2) Preparation of mixed additive solution: mix 25g of K2CO3 and 10g of NaHCO3 powder, add 135g of water to the mixed powder, stir, and prepare a mixed additive solution;

[0098] (3) Take 5g of the mixed additive solution prepared in step (2) and add it to 200g of the waste sand treated in step (1), stir uniformly, and stand for 4 hours;

[0099] (4) Low-temperature roasting: place the waste molding clay sand treated in step (3) in a horizontal roasting furnace and roast at 500°C for 30 minutes, and cool to room temperature;

[0100] (5) Grind the cast iron clay waste sand treated in step (4) in a ball mill for 0.5 hours, and then pass it through a vibrating screen to screen and recover the regenerated sand with a particle size of 40-140 mesh.

[0101] Comparative Example 6

[0102] A method for regenerating waste molding clay sand, comprising the following steps:

[0103] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, and the metal substances in the waste sand are removed by a magnetic separator, and then the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0104] (2) Preparation of mixed additive solution: 25 g of K2CO3 and 10 g of KNO3 powder are mixed, 135 g of water is added to the mixed powder, and the mixed additive solution is prepared by stirring;

[0105] (3) 5 g of the mixed additive solution prepared in step (2) is added to 200 g of the waste sand treated in step (1), and stirred uniformly, and then left to stand for 4 hours;

[0106] (4) Low-temperature roasting: the foundry clay waste sand treated in step (3) is placed in a horizontal roasting furnace and roasted at 500°C for 30 minutes, and then cooled to room temperature;

[0107] (5) The foundry clay waste sand treated in step (4) is ground in a ball mill for 0.5 hours, and then screened by a vibrating screen to recover the regenerated sand with a particle size of 40-140.

[0108] Comparative Example 7

[0109] A method for regenerating foundry clay waste sand, comprising the following steps:

[0110] (1) The foundry clay waste sand is crushed in a jaw crusher to obtain crushed fine sand with a particle size of less than 5 mm, and the metal substances in the waste sand are removed by a magnetic separator, and then the waste sand with a particle size of 40-140 is screened out by a grading vibrating screen;

[0111] (2) Preparation of mixed additive solution: 10 g of NaHCO3 and 10 g of KNO3 powder are mixed, 135 g of water is added to the mixed powder, and the mixed additive solution is prepared by stirring;

[0112] (3) 5 g of the mixed additive solution prepared in step (2) is added to 200 g of the waste sand treated in step (1), and stirred uniformly, and then left to stand for 4 hours;

[0113] (4) Low-temperature roasting: the foundry clay waste sand treated in step (3) is placed in a horizontal roasting furnace and roasted at 500°C for 30 minutes, and then cooled to room temperature;

[0114] (5) The foundry clay waste sand treated in step (4) is ground in a ball mill for 0.5 hours, and then screened by a vibrating screen to recover the regenerated sand with a particle size of 40-140.

[0115] The treated foundry clay waste sand of examples 1-4 and comparative examples 1-7 is subjected to performance testing, and the testing indexes are acid consumption value, electric conductivity value and ignition loss; wherein, the acid consumption value is determined by acid-base titration method, the electric conductivity value is measured by electric conductivity meter, and the ignition loss is determined by high temperature ignition value constant weight, and the mass difference is calculated. The test results are shown in Table 1.

[0116] Table 1

[0117]

[0118] As shown in Table 1, the mixed additive of the present application examples 1-4 using and oxidizing agent, under the condition of low temperature and short time calcination at 500℃, significantly improves the performance of the regenerated sand, and the acid consumption value is less than 5.3 ml, the electric conductivity is between 62-75 μS / cm, the ignition loss is controlled below 0.08%, and all indexes are better than comparative examples 1-7. In contrast, the acid consumption value of comparative example 1 without using additive is as high as 11.0 ml, and the ignition loss is 0.8%, while the performance of comparative examples 2-7 using single or double component additive is improved to some extent, but still significantly worse than the full component additive system of the present application, fully proving that and oxidizing agent have synergistic effect in catalyzing the oxidation of coal powder, destroying the clay structure and promoting the transmission of oxygen, which can efficiently realize the regeneration of clay sand under the condition of low temperature and short time, greatly reduce the energy consumption and equipment cost, and at the same time guarantee the high quality of regenerated sand and 100% recycling rate.

[0119] The above has further described the present application by means of specific examples, but it should be understood that the specific description here should not be understood as limiting the essence and scope of the present application, and various modifications of the above examples made by ordinary skilled in the art after reading the present specification are within the scope of the present application.

Claims

1. A method for recycling used foundry clay sand, characterized by, The method comprises the following steps: (1) crushing and magnetic separation of cast iron clay waste sand; (2) preparing a mixed additive solution: mixing K2CO3, NaHCO3 and an oxidizing agent to prepare a mixed additive powder, and preparing a mixed additive solution by mixing the mixed additive powder with water; (3) mixing the cast iron clay waste sand after magnetic separation in step (1) with the mixed additive solution prepared in step (2), stirring, and standing; (4) low-temperature roasting: low-temperature roasting the cast iron clay waste sand treated in step (3), and the low-temperature roasting temperature is 500 DEG C, and the time is 30-60 minutes; (5) grinding and screening the cast iron clay waste sand treated in step (4) to obtain regenerated sand.

2. The method of claim 1, wherein the method further comprises the step of: In step (2), K2CO3, NaHCO3 and the oxidizing agent are mixed in a mass ratio of (2-3):1:

1.

3. The method of claim 1, wherein the method further comprises the step of: The oxidizing agent is at least one of sodium chlorate, sodium chlorite and potassium nitrate.

4. The method of claim 2, wherein the method further comprises the step of: In step (2), the mass ratio of the mixed additive powder to water is (20-30):(80-90).

5. The method of claim 1, wherein the method further comprises the step of: In step (3), the mass ratio of the mixed additive solution to cast iron clay waste sand is (2-3):

100. ​ 6. The method of claim 1, wherein the method further comprises: The standing time is 4-5 hours.

7. The method of claim 1, wherein the method further comprises the step of: In step (1), a jaw crusher, a hammer crusher or an impact crusher is used to crush the cast iron clay waste sand, and the crushed fine sand with a particle size of less than 5 mm is obtained.

8. The method of claim 1, wherein the method further comprises: The cast iron clay waste sand after magnetic separation is classified and screened by a vibrating screen, and the crushed clay waste sand with a particle size of 60-100 mesh is screened out.

9. The method of claim 1, wherein the method further comprises the step of: In step (5), the grinding is performed by a ball mill or a vibration mill for 0.5-1 hour; and / or, The screening is performed by a vibrating screen or a drum screen, and the particle size of the regenerated sand after screening is 40-140 mesh.

10. The method of claim 1, wherein the method further comprises the step of: In step (4), the roasting is performed by a horizontal roasting furnace or a through-type roasting furnace. ​

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