Method for improving recycling rate of tape casting leftover materials

Abstract

The invention discloses a method for improving the recycling rate of tape-casting leftover materials, and relates to the technical field of ceramic material recycling, the method comprises the following steps: putting crushed tape-casting leftover materials into a glue discharging sintering furnace, and then carrying out staged heating treatment in a temperature range of 180-620 DEG C; after heating treatment, cooling to 40-60 DEG C to obtain degummed zirconium oxide powder; and carrying out ball milling treatment on the degummed zirconium oxide powder, and filtering to obtain the recycled zirconium oxide powder. After the tape casting leftover materials are treated by the process, the zirconium oxide powder which can be directly put into production and used can be recycled to the greatest extent under the condition that the product quality is not influenced. The recycled zirconium powder is low in impurity content, small in D50 particle size distribution and large in specific surface area, the defect rate of air holes and internal crack defects after a cast sheet prepared from the zirconium oxide powder recycled through the method is sintered is reduced, and meanwhile the bending strength after sintering is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic material recycling, and particularly relates to a method for improving the recycling rate of flow casting edge scraps. BACKGROUND

[0002] Flow casting edge scraps are a specific type of industrial waste generated in the flow casting process of ceramic powder. They are edge residues cut off during the processing of ceramic green film cutting, stamping and other processes to obtain the target shape, or unqualified green sheet fragments caused by size errors and process defects.

[0003] At present, flow casting edge scraps are directly landfilled or incinerated as hazardous waste, which will cause waste of precious metal resources and environmental pollution. The traditional process uses a single temperature and a single atmosphere to discharge glue, which cannot simultaneously meet the discharge of glue and impurity carbides and the protection of carbonized organic matter. The incomplete discharge of glue or the excessively high recycling ratio will lead to serious particle agglomeration, large specific surface area, large slurry viscosity fluctuation, and pore defects in the sintering process of the flow casting sheet, or high impurity content, which will lead to insufficient density in the sintering process of the flow casting sheet, resulting in internal crack defects.

[0004] In addition, the traditional process uses spiral extrusion grinding and screen filtration, and the recycled zirconia powder has a large particle size, which leads to serious particle agglomeration, large specific surface area, large slurry viscosity fluctuation, and pore defects in the sintering process of the flow casting sheet.

[0005] In addition, the existing process also uses wet ball milling and spray granulation, which has the problems of high slurry granulation cost, much wall hanging waste, high wastewater treatment cost, and complex process and large energy consumption. SUMMARY

[0006] Based on the problem that the current process method leads to low recycling rate of flow casting edge scraps, the purpose of the present application is to provide a method for improving the recycling rate of flow casting edge scraps, so that the flow casting edge scraps can be maximized to be recycled as zirconia powder that can be directly put into production after the process treatment without affecting the product quality.

[0007] The present application realizes the following technical scheme: The present application provides a method for improving the recycling rate of flow casting edge scraps, comprising the following steps: Put the crushed flow casting edge scraps into a glue discharge sintering furnace, and then perform stage heating treatment in the temperature range of 180 DEG C to 620 DEG C; After the heating treatment, cool to 40 DEG C to 60 DEG C to obtain the degummed zirconia powder; After the degummed zirconia powder is ball milled and filtered, the recycled zirconia powder is obtained.

[0008] Further, the stage-wise temperature rising treatment mode, in particular: First stage: after the temperature is raised to 180~220℃, air is introduced; Second stage: after the temperature is continuously raised to 280~320℃, air is introduced; Third stage: after the temperature is continuously raised to 480~520℃, nitrogen is introduced; Fourth stage: after the temperature is continuously raised to 580~620℃, air is introduced.

[0009] Among them, the preferred temperature value of the first stage is 200℃; the preferred temperature value of the second stage is 300℃; the preferred temperature value of the third stage is 500℃; and the preferred temperature value of the fourth stage is 600℃.

[0010] Further, the temperature is kept for 0.5~1.5h after air is introduced in the first stage; the temperature is kept for 1~3h after air is introduced in the second stage; the temperature is kept for 0.5~1.5h after nitrogen is introduced in the third stage; and the temperature is kept for 0.5~1.5h after air is introduced in the fourth stage.

[0011] Among them, the preferred temperature keeping time after air is introduced in the first stage is 1h, the preferred temperature keeping time after air is introduced in the second stage is 2h, the preferred temperature keeping time after nitrogen is introduced in the third stage is 1h, and the preferred temperature keeping time after air is introduced in the fourth stage is 1h.

[0012] Further, the cast edge corner material is crushed to a length-width size <1mm.

[0013] Further, when the cast edge corner material is subjected to the glue removal treatment, the temperature rising rate and the temperature falling rate are controlled to be 0.5~1.5℃ / min.

[0014] Among them, the preferred temperature rising rate and the temperature falling rate are 1℃ / min.

[0015] Further, the dry method ball milling is used to ball mill the degummed zirconia powder.

[0016] Further, when the degummed zirconia powder is subjected to the ball milling treatment, the zirconium beads with a size of 0.9~1.1mm are added.

[0017] Among them, the preferred size of the zirconium beads is 1.0mm.

[0018] Further, the mass ratio of the degummed zirconia powder to the zirconium beads is 1: (2.5~3.5).

[0019] Among them, the preferred mass ratio of the degummed zirconia powder to the zirconium beads is 1:3.

[0020] Further, the rotation speed during the ball milling treatment of the degummed zirconia powder is 195r / min~205r / min.

[0021] Preferably, the rotation speed during the ball milling treatment of the degummed zirconia powder is 200r / min.

[0022] Further, the degummed zirconia powder is filtered by using a 400 mesh~600 mesh filter screen.

[0023] Preferably, the filter screen used for filtering the degummed zirconia powder is a 500 mesh filter screen.

[0024] Compared with the prior art, the present application has the following advantages and beneficial effects: (1) The present application uses physical crushing, stage temperature control, degumming in different atmosphere environment, dry ball milling, and filter screen screening, so that the cast edge scraps are treated by the process, and the zirconia powder recovered can be directly used for production without affecting the product quality.

[0025] (2) The zirconia powder recovered by the method of the present application has less impurity content, small D50 particle size distribution, and large specific surface area, and the adverse rate of pores and internal cracks defects of the cast sheet sintered by using the zirconia powder recovered by the method is also reduced, and the bending strength after sintering is increased. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the example embodiments of the present application, the following will briefly introduce the drawings needed in the examples. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings: Figure 1 The process flow chart of the method for improving the recycling rate of cast edge scraps in the present application; Figure 2 The process flow chart of the recycling of cast edge scraps in Comparative Example 1; Figure 3 The process flow chart of the recycling of cast edge scraps in Comparative Example 2; Figure 4 The electron microscope morphology chart of the sintered cast sheet prepared by using the zirconia oxide recovered in Example 1 of the present application; Figure 5 The electron microscope morphology chart of the sintered cast sheet prepared by using the zirconia oxide recovered in Comparative Example 1; Figure 6 The electron microscope morphology chart of the sintered cast sheet prepared by using the zirconia oxide recovered in Comparative Example 2; Figure 7 Scanning electron micrograph of sintered cast sheet prepared from zirconia recovered in Comparative Example 4; Figure 8 Scanning electron micrograph of sintered cast sheet prepared from zirconia recovered in Comparative Example 5. DETAILED DESCRIPTION

[0027] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. The illustrative embodiments of the present application and their descriptions are only used to explain the present application and do not constitute limitations on the present application.

[0028] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one of ordinary skill in the art that the present application can be practiced without these specific details. In other instances, well-known materials or methods have not been described in detail in order to avoid obscuring the present application.

[0029] Throughout this specification, the term "one embodiment," "an embodiment," "one example," or "an example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. Therefore, the appearance of the phrases "in one embodiment," "in an embodiment," "in one example," or "in an example" in various places in the specification are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics can be combined in any suitable

[0030] The ranges disclosed herein are defined by their lower and upper limits. Ranges that include both endpoints are inclusive of the endpoints, and ranges that exclude both endpoints are not inclusive of the endpoints. Ranges are combinable and include any and all combinations of the stated ranges. For example, if a range of 60-120 and a range of 80-110 are listed, it is understood that a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and a maximum range value of 3 are listed, then ranges of 1-3, 1-2, 2-3, and 2-2 are all contemplated. In this application, unless otherwise indicated, a numerical range "a-b" means and is equivalent to the range of any and all subcombinations of the values between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means and is equivalent to the listing of all real numbers between 0 and 5, which has been abbreviated herein as "0-5." Also, when a parameter is stated to be an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise indicated, all steps of the methods of the present application can be performed in any order, and preferably are performed in the order presented. For example, the method comprising steps (a) and (b) means that the method can comprise steps (a) and (b) in the order presented, or the method can comprise steps (b) and (a) in the order presented. For example, the method comprising steps (a), (b), and (c) means that the method can comprise steps (a), (b), and (c) in the order presented, or the method can comprise steps (a), (c), and (b) in the order presented, or the method can comprise steps (c), (a), and (b) in the order presented, etc.

[0032] Example 1 This example provides a method for improving the recycling rate of cast edge corners, as shown in the following steps: Figure 1 The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge corners to a length and width size <1 mm.

[0033] S2, put the crushed edge corners into a glue removal sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1°C / min.

[0034] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0035] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0036] Example 2 This example provides a method for improving the recycling rate of cast edge scraps, which differs from Example 1 in that the temperature value controlled in the degumming stage is different. The specific steps are: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0037] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 180℃, then pass air for 1 hour, then continue to heat to 280℃, then pass air for 2 hours, then continue to heat to 480℃, then pass nitrogen for 1 hour, then continue to heat to 580℃, then pass air for 1 hour, then cool to 40℃, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0038] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0039] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0040] Example 3 This example provides a method for improving the recycling rate of cast edge scraps, which differs from Example 1 in that the temperature value controlled in the degumming stage is different. The specific steps are: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0041] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 220℃, then pass air for 1 hour, then continue to heat to 320℃, then pass air for 2 hours, then continue to heat to 520℃, then pass nitrogen for 1 hour, then continue to heat to 620℃, then pass air for 1 hour, then cool to 60℃, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0042] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0043] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0044] Example 4 This example provides a method for improving the recycling rate of cast edge scraps, which differs from Example 1 in that the air ventilation time in the degumming stage is different. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0045] S2, put the crushed edge scraps into a degumming sintering furnace, ventilate with air for 0.5 hours after heating to 200°C, then continue to ventilate with air for 1 hour after heating to 300°C, then continue to ventilate with nitrogen for 0.5 hours after heating to 500°C, then continue to ventilate with air for 0.5 hours after heating to 600°C, and then cool to 50°C to obtain the degummed zirconia powder. The program controls the heating and cooling rates at 1°C / min.

[0046] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0047] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0048] Example 5 This example provides a method for improving the recycling rate of cast edge scraps, which differs from Example 1 in that the air ventilation time in the degumming stage is different. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0049] S2, put the crushed edge scraps into a degumming sintering furnace, ventilate with air for 0.5 hours after heating to 200°C, then continue to ventilate with air for 1 hour after heating to 300°C, then continue to ventilate with nitrogen for 0.5 hours after heating to 500°C, then continue to ventilate with air for 0.5 hours after heating to 600°C, and then cool to 50°C to obtain the degummed zirconia powder. The program controls the heating and cooling rates at 1°C / min.

[0050] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0051] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0052] Example 6 This example provides a method for improving the recycling rate of the cast edge corners, and the difference between this example and Example 1 is that the heating and cooling rates are controlled differently. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge corners to a size of <1 mm in length and width.

[0053] S2, put the crushed edge corners into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 0.5°C / min.

[0054] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0055] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0056] Example 7 This example provides a method for improving the recycling rate of the cast edge corners, and the difference between this example and Example 1 is that the heating and cooling rates are controlled differently. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge corners to a size of <1 mm in length and width.

[0057] S2, put the crushed edge corners into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 0.5°C / min.

[0058] S3, the degummed zirconia powder and 1 mm zirconium beads are added into the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0059] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0060] Example 8 This example provides a method for improving the recycling rate of cast edge scraps. The difference between this example and Example 1 is that the size of the zirconium beads added in the ball milling stage is different. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a size of <1 mm in length and width.

[0061] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The rate of programmed temperature rise and fall is 1°C / min.

[0062] S3, the degummed zirconia powder and 0.9 mm zirconium beads are added into the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0063] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0064] Example 9 This example provides a method for improving the recycling rate of cast edge scraps. The difference between this example and Example 1 is that the size of the zirconium beads added in the ball milling stage is different. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a size of <1 mm in length and width.

[0065] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The rate of programmed temperature rise and fall is 1°C / min.

[0066] S3, the degummed zirconia powder and 1.1 mm zirconium beads are added into the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0067] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0068] Example 10 This example provides a method for improving the recycling rate of the cast edge scraps. Different from Example 1, the mass ratio of the degummed zirconia powder to the zirconium beads is different in this example. The specific steps are as follows: S1, the 3 kg of cast edge scraps are crushed to a size of <1 mm using a jaw crusher.

[0069] S2, the crushed edge scraps are placed into a degumming sintering furnace, and after being heated to 200℃, air is passed through for 1 hour, then after being continuously heated to 300℃, air is passed through for 2 hours, then after being continuously heated to 500℃, nitrogen is passed through for 1 hour, then after being continuously heated to 600℃, air is passed through for 1 hour, and then the temperature is lowered to 50℃ to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0070] S3, the degummed zirconia powder and 1 mm zirconium beads are added into the ball mill tank in a ratio of 1:2.5, and ball milling is performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0071] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0072] Example 11 This example provides a method for improving the recycling rate of the cast edge scraps. Different from Example 1, the mass ratio of the degummed zirconia powder to the zirconium beads is different in this example. The specific steps are as follows: S1, the 3 kg of cast edge scraps are crushed to a size of <1 mm using a jaw crusher.

[0073] S2, the crushed edge scraps are placed into a degumming sintering furnace, and after being heated to 200℃, air is passed through for 1 hour, then after being continuously heated to 300℃, air is passed through for 2 hours, then after being continuously heated to 500℃, nitrogen is passed through for 1 hour, then after being continuously heated to 600℃, air is passed through for 1 hour, and then the temperature is lowered to 50℃ to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0074] S3, the degummed zirconia powder and 1 mm zirconium beads are added into the ball mill tank at a ratio of 1:3.5, and ball milling is performed at a speed of 195 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0075] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0076] Example 12 This example provides a method for improving the recycling rate of the cast edge scraps. Different from example 1, the speed of ball milling the degummed zirconia powder is different in this example. The specific steps are as follows: S1, the 3 kg of cast edge scraps are crushed to a size of <1 mm using a jaw crusher.

[0077] S2, the crushed edge scraps are placed into a degumming sintering furnace, and after being heated to 200℃, air is passed through for 1 hour, then after being heated to 300℃, air is passed through for 2 hours, then after being heated to 500℃, nitrogen is passed through for 1 hour, then after being heated to 600℃, air is passed through for 1 hour, and then the temperature is lowered to 50℃, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0078] S3, the degummed zirconia powder and 1 mm zirconium beads are added into the ball mill tank at a ratio of 1:3.5, and ball milling is performed at a speed of 195 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0079] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recycled zirconia powder.

[0080] Example 13 This example provides a method for improving the recycling rate of the cast edge scraps. Different from example 1, the speed of ball milling the degummed zirconia powder is different in this example. The specific steps are as follows: S1, the 3 kg of cast edge scraps are crushed to a size of <1 mm using a jaw crusher.

[0081] S2, the crushed edge scraps are placed into a degumming sintering furnace, and after being heated to 200℃, air is passed through for 1 hour, then after being heated to 300℃, air is passed through for 2 hours, then after being heated to 500℃, nitrogen is passed through for 1 hour, then after being heated to 600℃, air is passed through for 1 hour, and then the temperature is lowered to 50℃, to obtain the degummed zirconia powder. The heating and cooling rates are controlled at 1℃ / min.

[0082] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 205 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0083] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0084] Example 14 This example provides a method for improving the recycling rate of cast edge scraps. Unlike Example 1, a 450 mesh filter screen is used in this example. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0085] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The rate of programmed temperature rise and fall is 1°C / min.

[0086] S3, the degummed zirconia powder and 1 mm zirconium beads are added to the ball mill tank in a ratio of 1:3, and ball milling is performed at a speed of 205 r / min for 24 hours. The total weight of the degummed zirconia powder and the zirconium beads is 20 kg.

[0087] S4, large particles are filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0088] Example 15 This example provides a method for improving the recycling rate of cast edge scraps. Unlike Example 1, a 450 mesh filter screen is used in this example. The specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast edge scraps to a length and width size of <1 mm.

[0089] S2, put the crushed edge scraps into a degumming sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The rate of programmed temperature rise and fall is 1°C / min.

[0090] S3, the degummed zirconia powder and 1 mm zirconium beads were added to the ball mill tank in a ratio of 1:3, and ball milling was performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and zirconium beads was 20 kg.

[0091] S4, large particles were filtered out using a 600 mesh filter screen to obtain the recovered zirconia powder.

[0092] Comparative Example 1 This comparative example provides a method for recycling cast-off materials, as shown in Figure 2 The specific steps are as follows: S1, a jaw crusher was used to crush 3 kg of cast-off materials to a size of <1 mm in length and width.

[0093] S2, the crushed edge material was placed in a degumming sintering furnace, and degumming was performed at 500°C for 5 hours with air. S3, the degummed zirconia powder was ground for 8 hours using a screw extruder.

[0094] S4, large particles were filtered out using a 500 mesh filter screen to obtain the recovered zirconia powder.

[0095] Comparative Example 2 This comparative example provides a method for improving the recycling rate of cast-off materials, as shown in Figure 3 The specific steps are as follows: S1, a jaw crusher was used to crush 3 kg of cast-off materials to a size of <1 mm in length and width.

[0096] S2, the crushed edge material was placed in a degumming sintering furnace, and degumming was performed at 500°C for 5 hours with air.

[0097] S3, the degummed zirconia powder and deionized water were ball milled in a ratio of 1:3 for 24 hours to form a slurry, and then spray granulation was performed to obtain the recovered zirconia powder.

[0098] Comparative Example 3 This comparative example provides a method for improving the recycling rate of cast-off materials, and the specific steps are as follows: S1, a jaw crusher was used to crush 3 kg of cast-off materials to a size of <1 mm in length and width.

[0099] S2, the crushed edge material was placed in a degumming sintering furnace, and degumming was performed at 500°C for 5 hours with air.

[0100] S3, the degummed zirconia powder and 1 mm zirconium beads were added to the ball mill tank in a ratio of 1:3, and ball milling was performed at a speed of 200 r / min for 24 hours. The total weight of the degummed zirconia powder and zirconium beads was 20 kg.

[0101] S4, filter out large particles using a 500-mesh filter screen to obtain the recovered zirconia powder.

[0102] Comparative Example 4 This comparative example provides a method for improving the recycling rate of cast-off materials, and the specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast-off materials to a size of <1 mm.

[0103] S2, put the crushed offcut into a glue removal sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The programmed control rate of heating and cooling is 1°C / min.

[0104] S3, use a spiral extrusion mill for 8 hours.

[0105] S4, filter out large particles using a 500-mesh filter screen to obtain the recovered zirconia powder.

[0106] Comparative Example 5 This comparative example provides a method for improving the recycling rate of cast-off materials, and the specific steps are as follows: S1, use a jaw crusher to crush 3 kg of cast-off materials to a size of <1 mm.

[0107] S2, put the crushed offcut into a glue removal sintering furnace, heat to 200°C, then pass air for 1 hour, then continue to heat to 300°C, then pass air for 2 hours, then continue to heat to 500°C, then pass nitrogen for 1 hour, then continue to heat to 600°C, then pass air for 1 hour, then cool to 50°C, to obtain the degummed zirconia powder. The programmed control rate of heating and cooling is 1°C / min.

[0108] S3, mix the degummed zirconia powder with deionized water in a ratio of 1:3, ball mill for 24 hours to form a slurry, then spray granulation to obtain the recovered zirconia powder.

[0109] Chemical composition analysis was performed on the zirconia powder recovered by the methods of Examples 1-15 and Comparative Examples 1-5, and the impurity content ratio was calculated; The D50 particle size of the zirconia powder recovered by the methods of Examples 1-15 and Comparative Examples 1-5 was measured using a laser particle size analyzer after dry ball milling; The specific surface area of the zirconia powder recovered by the methods of Examples 1-15 and Comparative Examples 1-5 was tested using a specific surface area tester; The zirconia powder recovered by the method of Examples 1-15 and Comparative Examples 1-5 was prepared into a slurry, and the viscosity before glue addition was tested using a digital viscometer.

[0110] The cast slurry preparation method is as follows: Step 1: 10 mm, 5 mm, and 3 mm zirconia beads were added in a weight ratio of 2:3:5, totaling 15 kg; Step 2: Add zirconia powder, dispersant, and mixed solvent, with a solid-liquid ratio of about 5:2; Step 3: Start the ball mill and set the rotation speed to 80±3 rpm, and run continuously for 72±1 hours.

[0111] The zirconia powder recovered by the method of Examples 1-15 and Comparative Examples 1-5 was prepared into a cast sheet, and the bending strength test was performed, and the data was counted.

[0112] The cast sheet preparation method is as follows: After the cast slurry is ball milled, it is vacuum degassed and then extruded into a casting device. The cast sheet is cut into the final shape after single-knife coating and warm zone baking. The bending strength test is performed, and the data is counted.

[0113] The above test results are shown in Table 1.

[0114] Table 1

[0115] From the experimental data analysis of Comparative Examples 1-5 and Examples 1-15, under the same granulation conditions, compared with single temperature and atmosphere degassing conditions: 1. The impurity ratio is significantly reduced (screw type grinding: from 0.844% to 0.046%; wet ball milling + spray granulation: from 0.907% to 0.041%; dry ball milling: from 0.738% to 0.043%).

[0116] 2. The viscosity tolerance range before glue addition is significantly narrowed (screw type grinding: from 20-90 mpa.s to 34-59 mpa.s; wet ball milling + spray granulation: from 27-69 mpa.s to 41-47 mpa.s; dry ball milling: from 26-66 mpa.s to 40-48 mpa.s).

[0117] 3. The porosity + internal crack defect rate is significantly reduced (screw type grinding: from 34.11% to 3.12%; wet ball milling + spray granulation: from 18.18% to 0.99%; dry ball milling: from 19.92% to 1.14%).

[0118] 4. The bending strength is obviously increased (from 313 Mpa to 448 Mpa; wet ball milling + spray granulation: from 444 Mpa to 799 Mpa; dry ball milling: from 406 Mpa to 665 Mpa).

[0119] Therefore, under the same granulation conditions, the recovery effect of different temperature and atmosphere degumming conditions is better than that of single temperature and atmosphere degumming conditions.

[0120] From the experimental data analysis of Comparative Examples 4-5 and Examples 1-15, under the same degumming temperature and atmosphere conditions, the comparison of the three granulation conditions of spiral grinding, wet ball milling + spray granulation and dry ball milling is as follows: 1. The porosity + internal crack defect rate: wet ball milling + spray granulation (0.99%) < dry ball milling (1.14%) < spiral grinding (3.12%); 2. The bending strength: wet ball milling + spray granulation (799 Mpa) > dry ball milling (665 Mpa) > spiral grinding (448 Mpa); 3. The recovery rate comparison: dry ball milling (68.8%) > spiral grinding (66.8%) > wet ball milling + spray granulation (36.7%); From the analysis of the porosity + internal crack defect rate and the bending strength, the process of wet ball milling + spray granulation is slightly better than that of dry ball milling, and the processes of wet ball milling + spray granulation and dry ball milling are both far superior to spiral grinding; but the recovery rate of the dry ball milling process is much higher than that of the wet ball milling + spray granulation process.

[0121] Therefore, under the same degumming temperature and atmosphere conditions, the dry ball milling process is the best.

[0122] The micro-morphology of the zirconia powder recovered by the method of Example 1 and Comparative Examples 1-5 is analyzed, as shown in Figure 4 The electron microscope morphology diagram of the sintered cast sheet prepared from the zirconia recovered in Example 1 of the present application is shown; Figure 5 The electron microscope morphology diagram of the sintered cast sheet prepared from the zirconia recovered in Comparative Example 1 is shown; Figure 6 The electron microscope morphology diagram of the sintered cast sheet prepared from the zirconia recovered in Comparative Example 2 and Comparative Example 3 is shown; Figure 7 The electron microscope morphology diagram of the sintered cast sheet prepared from the zirconia recovered in Comparative Example 4 is shown; Figure 8 The electron microscope morphology diagram of the sintered cast sheet prepared from the zirconia recovered in Comparative Example 5 is shown.

[0123] It can be seen from Figure 4 that: the sintered cast sheet prepared from the zirconia recovered in Example 1 has no porosity defect and no cracks.

[0124] It can be seen from Figure 5It can be seen that the cast sheet prepared from the recycled zirconia in Comparative Example 1 has serious porosity defects and cracks after sintering.

[0125] It can be seen that the cast sheet prepared from the recycled zirconia in Comparative Example 2 and Comparative Example 3 has slight porosity defects and serious cracks after sintering. Figure 6

[0126] It can be seen that the cast sheet prepared from the recycled zirconia in Comparative Example 4 has slight porosity defects and no cracks after sintering. Figure 7

[0127] It can be seen that the cast sheet prepared from the recycled zirconia in Comparative Example 5 has no porosity defects and no cracks after sintering, but the recovery rate is extremely low. Figure 8

[0128] In summary, the present application adopts physical crushing, stage temperature control and different atmosphere environment degassing, dry ball milling, and filter screen selection, so that the cast edge material is treated by the process, without affecting the product quality, and the zirconia powder directly used for production is maximized. The impurity content in the recycled zirconium powder is small, the D50 particle size distribution is small, the specific surface area is large, and the porosity and internal crack defects of the cast sheet prepared from the zirconia powder recovered by the method after sintering are also reduced, and the bending strength after sintering is increased.

[0129] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application.​​​

Claims

1. A method for improving the recycling rate of cast iron scraps, characterized in that, Includes the following steps: The crushed casting scraps are placed in a debinding sintering furnace and then subjected to staged heating treatment within a temperature range of 180℃~620℃. After heating, the temperature is lowered to 40℃~60℃ to obtain degummed zirconium oxide powder; The degummed zirconia powder was ball-milled and then filtered to obtain recovered zirconia powder.

2. The method for improving the recycling rate of cast iron scraps according to claim 1, characterized in that, The staged heating process is specifically as follows: First stage: After raising the temperature to 180℃~220℃, air is introduced; Second stage: Continue to heat to 280℃~320℃ and then introduce air; Third stage: Continue heating to 480℃~520℃ and then introduce nitrogen gas; Fourth stage: Continue to heat up to 580℃~620℃ and then introduce air.

3. The method for improving the recycling rate of cast iron scraps according to claim 2, characterized in that, The first stage involves introducing air and maintaining the temperature for 0.5 to 1.5 hours; the second stage involves introducing air and maintaining the temperature for 1 to 3 hours; the third stage involves introducing nitrogen and maintaining the temperature for 0.5 to 1.5 hours; and the fourth stage involves introducing air and maintaining the temperature for 0.5 to 1.5 hours.

4. The method for improving the recycling rate of cast iron scraps according to claim 1, characterized in that, The cast waste material is crushed to a length and width dimension of <1mm.

5. The method for improving the recycling rate of cast iron scraps according to claim 1, characterized in that, When removing glue from cast iron scraps, control the heating and cooling rates to be 0.5℃ / min to 1.5℃ / min.

6. The method for improving the recycling rate of cast iron scraps according to claim 1, characterized in that, The degummed zirconia powder was ball-milled using a dry ball milling method.

7. The method for improving the recycling rate of cast iron scraps according to claim 1, characterized in that, When ball milling the degummed zirconia powder, zirconia beads with a size of 0.9 mm to 1.1 mm are added.

8. A method for improving the recycling rate of cast iron scraps according to claim 7, characterized in that, The mass ratio of the degummed zirconium oxide powder to the zirconium beads is 1:(2.5~3.5).

9. A method for improving the recycling rate of cast iron scraps according to claim 7, characterized in that, The ball milling speed for the degummed zirconia powder was 195 r / min to 205 r / min.

10. A method for improving the recycling rate of cast iron scraps according to claim 7, characterized in that, The degummed zirconium oxide powder was filtered using a 400-600 mesh filter.

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