Lost foam reinforcing layer coating based on clay sand waste molding sand recycling and preparation method thereof

Abstract

The invention discloses an evanescent mode reinforcing layer coating based on recycling of clay sand waste molding sand and a preparation method thereof. The reinforcing layer coating is prepared from the following raw materials in parts by weight: 7 to 9 parts of auxiliaries, 40 to 100 parts of clay sand waste molding sand, 0 to 60 parts of mullite, 1 to 3 parts of lepidolite and 5 to 6 parts of water. By selecting proper grain size distribution, fully utilizing the clay sand waste molding sand, utilizing the suspension property and cohesiveness of the clay sand waste molding sand, and utilizing the characteristics of good angular coefficient and strong hydrophobicity of the quartz sand after repeated use, the drying time is shortened, the leveling property is extremely good, the thermal stability is good, the anti-corrosion effect is good, and the casting sand is suitable for castings made of cast steel and cast iron materials. And the clay sand waste sand is used as the refractory aggregate, so that the requirements of castings made of different materials are met, the economical efficiency is good, the damage to quartz sand resources is reduced, meanwhile, the drying time is greatly shortened, the energy conservation and consumption reduction are obvious, and the refractory material does not contain graphite, is environment-friendly and is simple to manufacture.

Description

Technical Field

[0001] The present invention relates to the technical field of low-carbon economy, and particularly to a lost foam reinforcing layer coating based on the recycling of waste clay sand and a preparation method thereof. Background Art

[0002] China is a major casting country. As a process for ferrous metal casting, the clay sand process has a wide range of applications because of its low cost, high recycling rate, and no use of organic binders during use. For example, the bolster side frames of the three major parts of railway freight cars are cast steel parts that use green sand for the outer mold and resin sand for the core.

[0003] In the prior art, during use, a small amount of clay is sintered into dead clay, a small amount is mixed with resin sand cores, steel slag, free carbon, etc., and the particle size of some quartz sand becomes smaller. Therefore, it is necessary to promptly eliminate a small amount of old waste sand and supplement new sand. This waste sand cannot be effectively used and is currently basically discharged as solid waste by the enterprises generating the waste sand, increasing the enterprise cost while wasting resources. Summary of the Invention

[0004] The purpose of the present invention is to provide a lost foam reinforcing layer coating based on the recycling of waste clay sand and a preparation method thereof, so as to solve the problems in the above background art that the waste sand cannot be effectively used and is currently basically discharged as solid waste by the enterprises generating the waste sand, increasing the enterprise cost while wasting resources.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A lost foam reinforcing layer coating based on the recycling of waste clay sand, the reinforcing layer coating is composed of the following raw materials in parts by weight: 7-9 parts by weight of additives, 40-100 parts by weight of waste clay sand, 0-60 parts by weight of mullite, 1-3 parts by weight of lepidolite, and 5-6 parts by weight of water.

[0006] A preparation method of a lost foam reinforcing layer coating based on the recycling of waste clay sand, comprising the following steps:

[0007] S1. Waste sand treatment: Select waste clay sand for impurity removal, iron removal and screening, and add mullite to the screened waste sand to form refractory aggregate;

[0008] S2. Coating mixing: Mix the additives, lepidolite and water to make a mixed additive, and then add the refractory aggregate after mixing to make a coating;

[0009] S3. Coating inspection: Take a lost foam sample, dip it in the slurry, observe the leveling property, whether chessboards are generated, then put it into an oven and dry it at 45-55 °C, and then observe the strength. After passing the inspection, it can be put into use.

[0010] Preferably, in step S1, the screened material is divided into material A with a mesh size of 40 - 70 and material B which is the material passing through a 70 - mesh sieve. The addition ratio of mullite is adjusted according to the material of the casting, the pouring temperature, the coating thickness, and the number of coating times. The mixed refractory aggregate is divided into type A refractory aggregate and type B refractory aggregate.

[0011] Preferably, in step S2, the auxiliary agent is Guilin No. 5 and contains a binder, a suspending agent, an antifoaming agent, and a preservative.

[0012] Preferably, in step S2, when mixing the auxiliary agent, it is stirred at a high speed by an electric motor for 20 - 30 minutes.

[0013] Preferably, in step S2, when mixing the auxiliary agent with the refractory aggregate, water is added and stirred for 1 - 2 hours, and then the Baume degree is measured to obtain coatings A and B.

[0014] Preferably, the stirring speed is 500 r / min, and it can be used after standing for 1 - 2 hours.

[0015] Preferably, in step S3, the dipping slurry times are three times. The drying time after the first dipping slurry is 2 - 2.5 h, the second time is 1.5 - 2 h, and the third time is 1.5 h.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] In the present invention, by selecting a suitable particle size distribution, the waste clay sand of the clay sand is fully utilized, and its suspension and adhesiveness are utilized. After repeated use, the quartz sand has good angularity coefficient, strong hydrophobicity, which shortens the drying time, and has excellent leveling property, good thermal stability, and good anti - corrosion effect. It is applicable to castings made of cast steel and cast iron materials, and uses the waste clay sand as the refractory aggregate to meet the requirements of castings with different materials, with good economy, reducing the damage to quartz sand resources. At the same time, the drying time of this method is greatly shortened, and the energy saving and consumption reduction are obvious. Since it does not contain graphite, it is environmentally friendly, does not require additional thixotropic agents, is simple to manufacture, has a long anti - corrosion time, and good sintering and peeling properties. Specific Embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0019] Example 1: A lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand. The reinforcing layer coating is composed of the following raw materials in parts by weight: 7-9 parts by weight of additives, 40-100 parts by weight of clay sand waste molding sand, 0-60 parts by weight of mullite, 1-3 parts by weight of lepidolite, and 5-6 parts by weight of water.

[0020] Example 2: A preparation method of a lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand, comprising the following steps:

[0021] Step 1. Waste sand treatment: Select clay sand waste molding sand for impurity removal, iron removal and screening. Add mullite to the screened waste sand to form refractory aggregate. The screened materials are divided into material A with a mesh size of 40-70 and material B which is the material passing through a 70-mesh sieve. The addition ratio of mullite is adjusted according to the material of the casting, the gradual temperature, the coating thickness, and the coating times. The mixed refractory aggregate is divided into type A refractory aggregate and type B refractory aggregate;

[0022] Step 2. Coating mixing: Mix the additives, lepidolite and water, and stir at high speed with an electric motor for 20-30 minutes to make a mixed additive. After mixing, add the refractory aggregate for mixing, add water and stir for 1-2 hours, and then test the Baume degree to obtain coatings A and B. The stirring speed is 500 r / min, and it can be used after standing for 1-2 hours. The additive is Guilin No. 5 and contains a binder, a suspending agent, an antifoaming agent and a preservative. The ratio of additive:lepidolite:water = 10:3:30-40;

[0023] Step 3. Coating inspection: Take a lost foam sample, dip it in the slurry, observe the leveling property and whether chessboards are generated, then put it into an oven and dry it at 45-55 °C, and then observe the strength. After passing the inspection, it can be put into use. The dipping times are three times. The drying time after the first dipping is 2-2.5 h, the second time is 1.5-2 h, and the third time is 1.5 h. The first layer of the two-layer coating uses a commercial coating, the second layer uses coating B, and the third layer uses coating A.

[0024] Practical application

[0025] The specific method of using the second-layer coating prepared by the present invention for producing ductile iron is as follows:

[0026] 1. Mix the waste sand and mullite to form refractory aggregate, and the component ratio is: waste sand 40%: mullite 60%. Make coating B for ductile iron, with a casting temperature of 1450-1480 °C, and the casting is a ductile iron water pipe elbow with two layers of coating.

[0027] 2. Weigh the refractory aggregate, additives, lepidolite, and water in the ratio of 100:10:3:50. First, add water to the additives and stir at high speed for 30 minutes to disperse them, then add the refractory aggregate, sintering and peeling material, and water, and stir at a speed of less than 550 revolutions per minute for more than 1.5 hours.

[0028] 3. Test the Baume degree, which should be between 65 and 75, and the strength test reaches the first-level standard. In this way, the production process of the second-layer reinforcement layer coating is completed.

[0029] 4. The first-layer coating is applied by dipping slurry according to the current process and technology, dried, and then dipped and dried with Coating B.

[0030] The specific method for making the three-layer composite coating for cast steel ZG35 is as follows:

[0031] Select waste sand with a particle size of 40-70 mesh and mullite with a particle size of 120-200 mesh. According to the ratio of waste sand 40%: mullite 60%, make Coating A according to the Coating A process. Coating B is made from 20% of the material passing through a 70-mesh sieve and 80% of 200-mesh mullite. Add commercial Coating C for the implementation of the three-layer coating for this casting.

[0032] The first layer is Coating C, with a Baume degree of 70-72. Take it out after drying for 4 hours, apply Coating B, with a Baume degree of 75-76 and a drying time of 1.5-2 hours. The third layer is Coating A, with a Baume degree of 70-72 and a drying time of 1.2-1.5 hours.

[0033] In the present invention, by selecting an appropriate particle size distribution, making full use of the waste clay sand, taking advantage of its suspension and adhesion properties, and the good angularity coefficient and strong hydrophobicity of the quartz sand after repeated use, the drying time is shortened, and it has excellent leveling property, good thermal stability, and good anti-corrosion effect. It is suitable for castings made of cast steel and cast iron. Using waste clay sand as the refractory aggregate can meet the requirements of castings with different materials, has good economy, reduces the damage to quartz sand resources. At the same time, the drying time of this method is greatly shortened, and energy conservation and consumption reduction are obvious. Since it does not contain graphite, it is environmentally friendly, does not require additional thixotropic agents, is simple to manufacture, has a long anti-corrosion time, and good sintering and peeling properties.

[0034] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lost foam reinforcing layer coating based on the recycling of clay sand waste foundry sand, characterized in that: The reinforcing layer coating is composed of the following raw materials in parts by weight: 7-9 parts by weight of additives, 40-100 parts by weight of clay sand waste sand, 0-60 parts by weight of mullite, 1-3 parts by weight of lepidolite, and 5-6 parts by weight of water.

2. A preparation method of a lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand, characterized in that: A lost foam reinforcing layer coating using the recycling of clay sand waste sand described in claim 1 includes the following steps: S1. Waste sand treatment: Select clay sand waste sand for impurity removal, iron removal and screening, and add mullite to the screened waste sand to form refractory aggregates; S2. Coating mixing: Mix the additives, lepidolite and water to make a mixed additive, and then add the refractory aggregates after mixing to make a coating; S3. Coating inspection: Take a lost foam sample, dip it in the slurry, observe the leveling property and whether chess pieces are generated, then put it in an oven and dry it at 45-55 °C, and then observe the strength. After passing the inspection, it can be put into use.

3. The preparation method of the lost foam reinforcement layer coating based on the recycling of clay sand waste foundry sand according to claim 2, characterized in that: In step S1, the screened material is divided into A material with a mesh size of 40-70, and the material passing through a 70-mesh sieve is B material. The addition ratio of mullite is adjusted according to the material of the casting, the gradual temperature, the coating thickness and the coating times. The mixed refractory aggregates are divided into A-class refractory aggregates and B-class refractory aggregates.

4. The preparation method of the lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand according to claim 2, characterized in that: In step S2, Guilin No. 5 additive is selected and contains a binder, a suspending agent, an antifoaming agent and a preservative.

5. The preparation method of the lost foam reinforcement layer coating based on the recycling of clay sand waste molding sand according to claim 2, characterized in that: In step S2, the mixed additive is stirred at a high speed by a motor for 20-30 minutes during mixing.

6. The preparation method of the lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand according to claim 2, characterized in that: In step S2, when the mixed additive is mixed with the refractory aggregates, water is added and stirred for 1-2 hours, and then the Baume degree is measured to obtain coatings A and B.

7. The preparation method of the lost foam reinforcing layer coating based on the recycling of clay sand waste molding sand according to claim 6, characterized in that: The stirring speed is 500 r / min, and it can be used after standing for 1-2 hours.

8. The preparation method of the lost foam reinforcement layer coating based on the recycling of clay sand waste molding sand according to claim 2, characterized in that: In step S3, the dipping times are three times. The drying time after the first dipping is 2-2.5 h, the second time is 1.5-2 h, and the third time is 1.5 h.