Black brick prepared from casting waste and preparation method thereof

Abstract

The invention discloses a black brick prepared from casting waste and a preparation method thereof, and belongs to the technical field of building materials, the black brick comprises the following components by weight: 260-300 parts of casting fly ash, 32-48 parts of clay waste sand, 15-25 parts of hard shale, 50-80 parts of soft shale, 10-20 parts of kaolin, 5-10 parts of hydroxymethyl cellulose, and 2-5 parts of barium carbonate. The method has the beneficial effects that the casting dedusting ash and the clay waste sand which are poor in performance, low in recovery value and difficult to treat are used as raw materials, and other auxiliary materials are combined for firing the black brick which can be used as a building material; by optimizing the particle size of the clay waste sand and utilizing a small amount of active clay on the surface of the clay waste sand, the drying shrinkage rate of the black brick is effectively reduced, the prepared black brick has high strength and good performance, secondary utilization of the casting fly ash and the clay waste sand is achieved, and good environmental benefits and economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a blue brick prepared from foundry waste and a preparation method thereof. Background Art

[0002] In 2023, China's casting output reached 51.9 million tons, among which clay sand casting played an important role. With the development of the recycling industry of clay waste sand, the casting dust ash produced in the recycling process has gradually received attention. It has a small particle size, complex composition, and is difficult to directly utilize as a resource. At present, in the solid waste resource utilization industry, a small amount of casting dust ash is used in unsintered bricks and expanded clay. However, due to the high temperature of the casting process and the regeneration process, the dust is inactivated and loses its viscosity. The prepared unsintered bricks and expanded clay have poor performance. At the same time, there are also serious problems such as alkali return and heavy metal pollution. As the use time increases, its performance deteriorates more seriously. The market acceptance is low, which hinders its resource utilization. Therefore, a method for effectively treating wastes such as clay waste sand and casting dust ash is needed. Summary of the invention

[0003] In order to overcome the problems in the prior art that foundry dust ash and clay waste sand have degraded performance after long-term use, have low recovery value and are difficult to handle, the present invention provides a green brick prepared from foundry waste, which comprises the following components by weight: 260-300 parts of foundry dust ash, 32-48 parts of clay waste sand, 15-25 parts of hard shale, 50-80 parts of soft shale, 10-20 parts of kaolin, 5-10 parts of hydroxymethyl cellulose and 2-5 parts of barium carbonate.

[0004] Preferably, the weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:3-1:8. The front-stage ash has better viscosity, but the higher organic content will cause the inside of the brick to turn black and affect the strength of the final product; while the rear-stage ash has a lower organic content. Under this ratio, the two make the green bricks have higher strength.

[0005] Preferably, the hard shale and the soft shale are both piled and aged for more than half a year, so that the components of the hard shale and the soft shale are more homogeneous and the composition properties are stable, thereby making the quality of the blue bricks more stable.

[0006] Preferably, the particle size of the clay waste sand is 24-40 mesh. If the particle size is too large, it will be difficult to bond stably and reduce the strength of the green brick; if the particle size is too large, it will lead to insufficient bonding force and cause the green brick to warp, shrink and crack easily, and also reduce the water permeability of the green brick.

[0007] In addition, the present invention also provides a method for preparing blue bricks using foundry waste, comprising the following steps:

[0008] S1, weighing each component and mixing them to obtain a mixture;

[0009] S2, adding water to the mixture, stirring, and sealing and aging to obtain a blank;

[0010] S3, extruding the blank into a brick blank and drying it;

[0011] S4, baking and reducing the dried brick embryo to obtain a green brick.

[0012] Preferably, in S1: each component is placed in a mixer with a rotor of 3200-4800 rpm and a pot of 40-60 rpm and stirred for 1-2 hours to obtain a mixture.

[0013] Preferably, in S2: water is added to the mixture and stirred in a mixer with a rotor of 300-500 rpm and a pot of 40-60 rpm for 1-2 hours, the mass of the water being 15-20% of the mass of the mixture, and after stirring, the mixture is sealed and aged for 24-36 hours.

[0014] Preferably, in S3: the blank is pressed into a brick blank at a pressure of 8-12 MPa, and the brick blank is left to stand for 24-36 hours and then dried at an ambient temperature of 60-80° C. until the moisture content of the brick blank is 1-2%.

[0015] Preferably, in S4: the calcination temperature is 950-1050° C., and the calcination time is 48-72 h.

[0016] Beneficial effects:

[0017] The beneficial effects produced by the technical solution of the present invention are as follows:

[0018] This solution utilizes foundry dust and clay waste sand with poor performance, low recycling value and difficulty in handling as raw materials, and combines them with other auxiliary materials to burn green bricks that can be used as building materials. By optimizing the particle size of the clay waste sand and utilizing a small amount of active clay on the surface of the clay waste sand, the drying shrinkage rate of the green bricks is effectively reduced. The prepared green bricks have higher strength and good performance. The present invention realizes the secondary utilization of foundry dust and clay waste sand, and has good environmental and economic benefits. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the embodiments is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0020] This embodiment utilizes foundry dust and clay waste sand with poor performance, low recycling value and difficult handling as raw materials, and combines with other auxiliary materials to burn green bricks that can be used as building materials. By optimizing the particle size of the clay waste sand and utilizing a small amount of active clay on the surface of the clay waste sand, the drying shrinkage rate of the green bricks is effectively reduced. The prepared green bricks have high strength and good performance. The present invention realizes the secondary utilization of foundry dust and clay waste sand, and has good environmental and economic benefits. The specific implementation is as follows:

[0021] A blue brick prepared from foundry waste comprises the following components by weight: 260-300 parts of foundry dust, 32-48 parts of clay waste sand, 15-25 parts of hard shale, 50-80 parts of soft shale, 10-20 parts of kaolin, 5-10 parts of hydroxymethyl cellulose and 2-5 parts of barium carbonate.

[0022] Specifically, the weight ratio of the front-end ash to the rear-end ash of the casting dust removal ash is 1:3-1:8. The front-end ash has better viscosity, but the higher organic content will cause the inside of the brick to turn black, affecting the strength of the final product; while the rear-end ash has a lower organic content. Under this ratio, the two make the green brick have higher strength.

[0023] Specifically, the hard shale and the soft shale are both piled and aged for more than half a year, so that the components of the hard shale and the soft shale are more homogeneous and the composition properties are stable, thereby making the quality of the blue bricks more stable.

[0024] Specifically, the particle size of the clay waste sand is 24-40 mesh. If the particle size is too large, it will be difficult to bond stably and reduce the strength of the green brick; if the particle size is too large, it will lead to insufficient bonding force, causing the green brick to warp, shrink and crack easily, and also reduce the water permeability of the green brick.

[0025] In addition, the present invention also provides a method for preparing blue bricks using foundry waste, comprising the following steps:

[0026] S1, weighing each component and mixing them to obtain a mixture;

[0027] S2, adding water to the mixture, stirring, and sealing and aging to obtain a blank;

[0028] S3, extruding the blank into a brick blank and drying it;

[0029] S4, baking and reducing the dried brick embryo to obtain a green brick.

[0030] Specifically, in S1: each component is put into a mixer with a rotor of 3200-4800 rpm and a pot of 40-60 rpm and stirred for 1-2 hours to obtain a mixture.

[0031] Specifically, in S2: water is added to the mixture and stirred in a mixer at a rotor of 300-500 rpm and a pot of 40-60 rpm for 1-2 hours, the mass of the water being 15-20% of the mass of the mixture, and after stirring, the mixture is sealed and aged for 24-36 hours.

[0032] Specifically, in S3: the blank is pressed into a brick blank at a pressure of 8-12 MPa, and the brick blank is left to stand for 24-36 hours and then dried at an ambient temperature of 60-80° C. until the moisture content of the brick blank is 1-2%.

[0033] Specifically, in S4: the calcination temperature is 950-1050° C., and the calcination time is 48-72 hours.

[0034] The present invention will be further explained below in conjunction with specific embodiments and comparative examples.

[0035] Example 1

[0036] In this embodiment, the green bricks contain the following components by weight:

[0037] 260 parts of foundry dust ash, 32 parts of clay waste sand, 15 parts of hard shale, 50 parts of soft shale, 10 parts of kaolin, 5 parts of hydroxymethyl cellulose, and 2 parts of barium carbonate.

[0038] The weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:3;

[0039] Both hard shale and soft shale were piled and aged for one year;

[0040] The particle size of clay waste sand is 24 mesh.

[0041] The production steps of the blue brick in this embodiment are:

[0042] S1, after weighing each component, put each component into a mixer with a rotor of 3200 rpm and a pot of 40 rpm and stir for 1 hour to obtain a mixture;

[0043] S2, adding water to the mixture and stirring in a mixer at a rotor of 300 rpm and a pot of 40 rpm for 1 hour, the mass of water being 15% of the mass of the mixture, and sealing and aging for 24 hours after stirring to obtain a blank;

[0044] S3, the blank is pressed into a brick blank under a pressure of 8 MPa, and the brick blank is left to stand for 24 hours and then dried at an ambient temperature of 60° C. until the moisture content of the brick blank is 1%;

[0045] S4, the dried brick embryo is roasted and reduced to obtain a green brick, the roasting temperature is 950° C., and the roasting time is 48 hours.

[0046] Example 2

[0047] In this embodiment, the green bricks contain the following components by weight:

[0048] 280 parts of foundry dust ash, 40 parts of clay waste sand, 20 parts of hard shale, 65 parts of soft shale, 15 parts of kaolin, 7 parts of hydroxymethyl cellulose, and 4 parts of barium carbonate.

[0049] The weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:5;

[0050] Both hard shale and soft shale were piled and aged for one year;

[0051] The particle size of clay waste sand is 32 mesh.

[0052] The production steps of the blue brick in this embodiment are:

[0053] S1, after weighing each component, put each component into a mixer with a rotor of 4000 rpm and a pot of 50 rpm and stir for 1.5 hours to obtain a mixture;

[0054] S2, adding water to the mixture and stirring in a mixer at a rotor of 400 rpm and a pot of 50 rpm for 1.5 h, the mass of water being 17% of the mass of the mixture, and sealing and aging for 30 h after stirring to obtain a blank;

[0055] S3, the blank is pressed into a brick blank under a pressure of 10 MPa, and the brick blank is left to stand for 30 hours and then dried at an ambient temperature of 70° C. until the moisture content of the brick blank is 1.5%;

[0056] S4, baking and reducing the dried brick embryo to obtain green brick, the baking temperature is 1000°C, and the baking time is 60h.

[0057] Example 3

[0058] In this embodiment, the green bricks contain the following components by weight:

[0059] 300 parts of foundry dust ash, 48 parts of clay waste sand, 25 parts of hard shale, 80 parts of soft shale, 20 parts of kaolin, 10 parts of hydroxymethyl cellulose, and 5 parts of barium carbonate.

[0060] The weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:8;

[0061] Both hard shale and soft shale were piled and aged for one year;

[0062] The particle size of clay waste sand is 40 mesh.

[0063] The production steps of the blue brick in this embodiment are:

[0064] S1, after weighing each component, put each component into a mixer with a rotor of 4800 rpm and a pot of 60 rpm and stir for 2 h to obtain a mixture;

[0065] S2, adding water to the mixture and stirring in a mixer at a rotor of 500 rpm and a pot of 60 rpm for 2 h, wherein the mass of the water is 20% of the mass of the mixture, and after the stirring is completed, the mixture is sealed and aged for 36 h to obtain a blank;

[0066] S3, the blank is pressed into a brick blank under a pressure of 12 MPa, and the brick blank is left to stand for 36 hours and then dried at an ambient temperature of 80° C. until the moisture content of the brick blank is 2%;

[0067] S4, the dried brick embryo is roasted and reduced to obtain a green brick, the roasting temperature is 1050°C, and the roasting time is 72h.

[0068] Comparative Example 1

[0069] In this comparative example, the components contained in the blue bricks are the same as those in Example 2 except for 250 parts of foundry dust ash and 30 parts of clay waste sand in terms of weight.

[0070] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0071] Comparative Example 2

[0072] In this comparative example, the components contained in the blue bricks are the same as those in Example 2 except for 320 parts of foundry dust ash and 52 parts of clay waste sand in parts by weight.

[0073] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0074] Comparative Example 3

[0075] In this comparative example, the components contained in the blue bricks are the same as those in Example 2 in terms of weight, except for 3 parts of hydroxymethyl cellulose.

[0076] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0077] Comparative Example 4

[0078] In this comparative example, the components contained in the blue bricks are the same as those in Example 2 in terms of weight, except for 12 parts of hydroxymethyl cellulose.

[0079] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0080] Comparative Example 5

[0081] The components contained in the green bricks in this comparative example are the same as those in Example 2 in terms of weight, except that the weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:2.

[0082] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0083] Comparative Example 6

[0084] The components contained in the green bricks in this comparative example are the same as those in Example 2 in terms of weight, except that the weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:9.

[0085] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0086] Comparative Example 7

[0087] The components contained in the green bricks in this comparative example are the same as those in Example 2 in terms of weight, except that the hard shale and the soft shale are both stacked and aged for 5 months.

[0088] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0089] Comparative Example 8

[0090] The components contained in the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage, except that the particle size of the clay waste sand is 20 mesh.

[0091] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0092] Comparative Example 9

[0093] The components contained in the green bricks in this comparative example are the same as those in Example 2 in terms of weight, except that the particle size of the clay waste sand is 45 mesh.

[0094] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2.

[0095] Comparative Example 10

[0096] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0097] In this comparative example, the production steps and conditions of the blue bricks are the same as those of Example 2, except that the mass of water added is 13% of the mass of the mixture.

[0098] Comparative Example 11

[0099] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0100] In this comparative example, the production steps and conditions of the blue bricks are the same as those of Example 2, except that the mass of water added is 23% of the mass of the mixture.

[0101] Comparative Example 12

[0102] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0103] In this comparative example, the production steps and conditions of the blue bricks are the same as those of Example 2 except that the firing temperature is 930°C.

[0104] Comparative Example 13

[0105] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0106] In this comparative example, the production steps and conditions of the blue bricks are the same as those of Example 2 except that the firing temperature is 1070°C.

[0107] Comparative Example 14

[0108] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0109] The production steps and conditions of the blue bricks in this comparative example are the same as those in Example 2 except that the firing time is 45 h.

[0110] Comparative Example 15

[0111] The components and specifications of the green bricks in this comparative example are the same as those in Example 2 in terms of weight percentage.

[0112] In this comparative example, the production steps and conditions of the blue bricks are the same as those of Example 2 except that the firing time is 75 h.

[0113] The compressive strength, flexural strength and water absorption of the green bricks prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 1 below.

[0114] Table 1. Test results of blue brick performance

[0115]

[0116]

[0117] It can be seen from the test results of the above Examples 1-3 that within the scope of the component ratio and the production method given in the present application, the green bricks produced using discarded foundry dust ash and clay waste sand as raw materials have better compressive strength, flexural strength and water absorption rate; combined with the test results of Example 2 and Comparative Examples 1-4, it can be seen that when there are too many or too few components, the strength and water absorption rate of the green bricks will be reduced.

[0118] It can be seen from the test results of Example 2 and Comparative Examples 5-11 that: when there is too little ash in the back stage, more organic matter in the front stage ash leads to black core of the blue brick and reduces the strength of the blue brick, while too much ash in the back stage leads to insufficient sticky front stage ash, which also affects the strength of the blue brick. At the same time, insufficient shale aging time will lead to material unevenness and thus affect the performance of the blue brick. If the particle size of the waste clay sand used is too large, it will be difficult to bond stably and reduce the strength of the blue brick. If the particle size is too large, it will lead to insufficient bonding force and cause the blue brick to warp, shrink and crack easily, and also reduce the water permeability of the blue brick. The right amount of water can help the molding and firing of the blue brick, while too little or too much water will have an adverse effect on the compressive strength, flexural strength and water absorption of the blue brick.

[0119] It can be seen from the test results of Example 2 and Comparative Examples 12-15 that insufficient firing time and insufficient firing temperature will reduce the strength and water absorption performance of the green bricks; while too long firing time and too high firing temperature will not improve the performance of the green bricks, but will cause a waste of time and resources.

[0120] In summary, within the component ratios, raw material specifications and production steps given in this scheme, this scheme utilizes foundry dust ash and clay waste sand with poor performance, low recovery value and difficulty in handling as raw materials, and combines them with other auxiliary materials to burn green bricks that can be used as building materials. By optimizing the particle size of the clay waste sand and utilizing a small amount of active clay on the surface of the clay waste sand, the drying shrinkage rate of the green bricks is effectively reduced. The prepared green bricks have higher strength and good performance. The present invention realizes the secondary utilization of foundry dust ash and clay waste sand, and has good environmental and economic benefits.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A blue brick made from foundry waste, characterized in that: The invention comprises the following components by weight: 260-300 parts of foundry dust ash, 32-48 parts of clay waste sand, 15-25 parts of hard shale, 50-80 parts of soft shale, 10-20 parts of kaolin, 5-10 parts of hydroxymethyl cellulose and 2-5 parts of barium carbonate.

2. The green brick made from foundry waste according to claim 1, characterized in that: The weight ratio of the front-stage ash to the rear-stage ash of the casting dust removal ash is 1:3-1:

8.

3. The green brick made from foundry waste according to claim 1, characterized in that: The hard shale and the soft shale are both piled and aged for more than half a year.

4. The green brick made from foundry waste according to claim 1, characterized in that: The particle size of the clay waste sand is 24-40 meshes.

5. A method for preparing blue bricks using foundry waste according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, weighing each component and mixing them to obtain a mixture; S2, adding water to the mixture, stirring, and sealing and aging to obtain a blank; S3, extruding the blank into a brick blank and drying it; S4, baking and reducing the dried brick embryo to obtain a green brick.

6. The method for preparing blue bricks using foundry waste according to claim 5, characterized in that: In S1: each component is put into a mixer with a rotor of 3200-4800 rpm and a pot of 40-60 rpm and stirred for 1-2 hours to obtain a mixture.

7. The method for preparing blue bricks using foundry waste according to claim 5, characterized in that: In S2: water is added to the mixture and stirred in a mixer at a rotor of 300-500 rpm and a pot of 40-60 rpm for 1-2 hours, the mass of the water being 15-20% of the mass of the mixture. After stirring, the mixture is sealed and aged for 24-36 hours.

8. The method for preparing blue bricks using foundry waste according to claim 5, characterized in that: In S3: the blank is pressed into a brick blank under a pressure of 8-12 MPa, and the brick blank is left to stand for 24-36 hours and then dried at an ambient temperature of 60-80° C. until the moisture content of the brick blank is 1-2%.

9. The method for preparing blue bricks using foundry waste according to claim 5, characterized in that: In S4: the calcination temperature is 950-1050°C and the calcination time is 48-72h.

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