A method for preparing a low cost foundry binder

Abstract

The application discloses a preparation method of a low-cost casting binder and belongs to the technical field of casting materials. The preparation method of the low-cost casting binder is low in cost and simple in preparation method. The emulsified asphalt has the characteristics of large bonding strength and stable durability, and the raw materials have the advantages of energy saving, environmental protection and renewability. After water glass is added into the anionic emulsified asphalt as a pH regulator, the pH value of the emulsifier aqueous solution can be adjusted, the asphalt emulsion can be thickened, and the storage stability of the asphalt emulsion can be improved. The water glass used in the production of the low-cost casting binder can adjust the pH value and has good water solubility. The water solubility is alkaline. The water glass is a colorless and transparent or light gray viscous liquid. Moreover, the water glass aqueous solution can further improve the strength of the casting binder by chemically reacting with carbon dioxide and simultaneously precipitating silicate gel. The casting binder has high economic benefits and environmental protection benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of foundry molding sand, and particularly relates to a preparation method of a low-cost foundry binder. BACKGROUND

[0002] With the continuous development of industry and agriculture and science and technology, new foundry binders are constantly emerging. At present, there are many types of foundry binders used in China. In the past, tung oil, catalpa oil, linseed oil, fish oil or resin were used. However, clay binder is still the most important foundry binder. Although chemical binders have developed rapidly in recent years, the production of domestic castings is still dominated by clay type, accounting for more than 80% of the total output of castings. Clay type sand is composed of silica sand, clay, coal powder and the like, which causes serious dust pollution and black pollution. During pouring, the combustion and decomposition of coal powder at high temperature produce harmful gases, which also cause air pollution. Resin sand is usually composed of an organic resin binder and a curing agent, p-toluenesulfonic acid. There are many sulfur dioxide toxic gases in the air of the production site. Especially for nodular iron and steel castings, a large amount of sulfur dioxide and nitrogen gas is produced during pouring due to decomposition, which often causes casting defects such as sulfur penetration, carbon penetration and nitrogen porosity in the absence of a coating layer shield, resulting in a decrease in mechanical properties of the castings and an increase in the scrap rate. For example, CN01805943.0 discloses a furan self-hardening foundry binder and its use, and CN202011097606.3 low-cost furan resin. There are many types of resin binders used in casting, mainly including phenolic resin, urea-formaldehyde resin and furfuryl alcohol resin. The casting process performance of the above three types of resin has certain limitations and cannot fully meet the requirements of casting production. Modified treatment with a complex process and high cost is still needed. There is an urgent need for a preparation method of a low-cost foundry binder to meet the existing use requirements and performance requirements. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a preparation method of a low-cost foundry binder.

[0004] The preparation method of the low-cost foundry binder comprises the following steps: in the first step, plant pitch 60-65 parts, water 30-35 parts and anionic emulsifier 7-10 parts are weighed according to the weight fraction; in the second step, the anionic emulsifier is added to the weighed water to form an emulsifier aqueous solution, and then heated to 50-70 DEG C, and then the water glass solution is added to adjust the pH value to 11-12 to obtain an emulsifier soap solution; in the third step, the plant pitch is heated to 100-110 DEG C and mixed with the emulsifier soap solution obtained in the second step to obtain an emulsified plant pitch by using an emulsifying machine through an emulsification process, and the low-cost foundry binder is obtained.

[0005] Plant pitch is the by-product of plant oil refining or the pyrolysis product of agricultural and forestry crops. It is called plant pitch because of its color like pitch. For example, biomass raw materials such as crop straw and rice husk are pyrolyzed, cooled, heated, and self-polymerized by stirring to remove water from the straw oil, and plant pitch can be obtained. Plant pitch has been widely used in high-grade highways, such as the Heguda Highway Xiaoguling to Fushun segment Dunhua connecting line.

[0006] Further, the emulsifying machine of the third step is a colloid mill or a high-speed shearing homogenizer.

[0007] Further, the anionic emulsifier of the second step is one of an anionic fast-cracking fast-setting emulsifier, an anionic slow-cracking fast-setting emulsifier, or an anionic slow-cracking slow-setting emulsifier.

[0008] Further, the plant pitch of the first step is a plant pitch with a penetration of 60-100 at 25°C, 5s, and 100g.

[0009] Further, the modulus of the water glass solution of the second step is 3.0-3.5.

[0010] Further, the emulsification process of the third step is an emulsification speed of 4000-5000r / min and an emulsification time of 4-6min.

[0011] The preparation method of the low-cost foundry binder has low cost and simple preparation method. At present, the price of plant pitch is 2000 yuan / ton, and the cost of organic resin foundry binder represented by furan resin is about 20,000 to 30,000 yuan / ton, which causes the cost of the final product to increase by more than 1000 yuan / ton. Moreover, although the price of furan resin has risen in recent years, compared with the cost of other types of self-hardening resin sand, the cost of furan resin sand is the lowest. The low-cost foundry binder disclosed by the application is only 1 / 10 of the organic resin foundry binder. Moreover, the plant pitch has the advantages of energy saving, environmental protection, and renewable, and the application of the plant pitch in the foundry binder has high economic benefits and environmental benefits. The emulsified pitch has the characteristics of high bonding strength and stable durability. After the water glass is added to the anionic emulsified pitch as a pH regulator, the pH value of the emulsifier aqueous solution can be adjusted, the pH value of the solution changes little, the hydrolysis of carboxylic acid soap is prevented, and insoluble fatty acids are generated. The strength of the emulsifier film on the surface of the emulsified pitch particles is increased, the emulsified pitch has a thickening effect on the pitch emulsion, and the storage stability of the pitch emulsion is improved. The water glass can also reduce the freezing point of the emulsion, form a precipitate with metal ions, soften water, have good wetting and emulsifying effects, and further reduce the amount of anionic emulsifier. It is found in practice that the water glass used in the production of the low-cost foundry binder has good water solubility and is alkaline in water solubility. The water-soluble water glass is a colorless and transparent or light gray viscous liquid. Moreover, the water glass aqueous solution can also react with carbon dioxide to generate silicate gel, and further improve the strength of the foundry binder. DETAILED DESCRIPTION

[0012] The application will be described in detail below with specific examples, but is not limited to the application. Example 1

[0013] Raw materials and equipment: Xinfaruijie No. 60 plant pitch is a plant pitch with a needle penetration degree of 60 at 25℃, 5s, and 100g, an anionic emulsifier, a water glass with a modulus of 3.0, and Fengqiu Dayang YY-KK-1 anionic fast-setting and fast-curing emulsifier.

[0014] The preparation method of the low-cost foundry binder comprises the following steps: in the first step, the plant pitch, water, and anionic emulsifier are weighed according to the weight fraction, and the water glass solution is added to adjust the pH value to 11 to obtain the emulsifier soap solution; in the second step, the plant pitch is heated to 100℃ and mixed with the emulsifier soap solution obtained in the first step to obtain the emulsified plant pitch by the emulsification process, and the emulsification process is that the emulsification speed is 4000r / min and the emulsification time is 4min.

[0015] Product: no pollution, good labor conditions, surface non-hygroscopic, winter hard no effect, good surface stability, easy to clean. Example 2

[0016] Raw materials and equipment: Huachi Chemical 80 plant pitch is a plant pitch with a penetration of 80 at 25℃, 5s, 100g, anionic emulsifier, modulus 3.2 water glass, Tongxushengda SD-MK anionic slow crack fast setting emulsifier.

[0017] The preparation method of the low-cost casting binder is characterized by comprising the following steps: first, weighing by weight fraction: plant pitch 62 parts, water 33 parts, anionic emulsifier 8 parts; second, adding anionic emulsifier to the weighed water to form an emulsifier aqueous solution, then heating to 60℃ and adding water glass solution to adjust the pH value to 12 to obtain an emulsifier soap solution; third, mixing the plant pitch heated to 105℃ with the emulsifier soap solution obtained in the second step to prepare an emulsified plant pitch by an emulsification process, and the emulsification process is that the emulsification speed is 4800r / min and the emulsification time is 5min. The low-cost casting binder is obtained. Example 3

[0018] Raw materials and equipment: Tuannong biomass 100 plant pitch is a plant pitch with a penetration of 100 at 25℃, 5s, 100g, anionic emulsifier, modulus 3.5 water glass, KZW-803Y anionic slow crack slow setting emulsifier.

[0019] The preparation method of the low-cost casting binder is characterized by comprising the following steps: first, weighing by weight fraction: plant pitch 62 parts, water 33 parts, anionic emulsifier 8 parts; second, adding anionic emulsifier to the weighed water to form an emulsifier aqueous solution, then heating to 60℃ and adding water glass solution to adjust the pH value to 12 to obtain an emulsifier soap solution; third, mixing the plant pitch heated to 105℃ with the emulsifier soap solution obtained in the second step to prepare an emulsified plant pitch by an emulsification process, and the emulsification process is that the emulsification speed is 4800r / min and the emulsification time is 5min. The low-cost casting binder is obtained.

[0020] Comparative Example 1

[0021] YDS03 density 1.50g / cm 3 The water glass binder, wherein the amount of MDT903 organic ester added accounts for 15% of the amount of water glass. The surface is hygroscopic, difficult to recover, poor collapsibility, hard and not transparent in winter, easy to powder, 4kg load collapsibility 1000℃ collapse time is greater than 200s, difficult to discharge waste sand, poor labor conditions.

[0022] Comparative Example 2

[0023] Compared with Example 2, this comparative example uses sodium hydroxide solution instead of water glass solution, but the rest of the steps are the same.

[0024] The casting binders of Examples 1-3, Comparative Example 1, and Comparative Example 2 were subjected to performance tests, and the test results are shown in Table 1.

[0025] Table 1 Performance test results of Examples 1-3

[0026] Item Tensile strength at room temperature MPa Usable time min Gas evolution ml / g Disintegration at 1000°C 35 s Strength at 800°C 10 min Example 1 2.44 15~25 14.2 100% 0.17 Example 2 2.35 25~40 13.3 100% 0.13 Example 3 2.51 60~120 14.8 100% 0.16 Comparative Example 1 0.87 20~40 6.5 No disintegration 0.41 Comparative Example 2 2.13 25~40 13.4 100% 0.12

[0027] Note: GB / T25138 Method for Determination of Tensile Strength at Room Temperature: Standard sand conforms to JB / T9224. Foundry binder. Equipment: SWY type hydraulic strength testing machine; SHY blade-type sand mixer, capacity 3kg; "8" shaped standard sample mold (the standard dimensions of the "8" shape inside the mold conform to GB / T2684, and the mold material is metal). Platform scale: 10kg. Balance: sensitivity 0.1g. Wet and dry thermometer. Sample preparation and storage: Test conditions: Sand temperature 20℃; room temperature 20℃; relative humidity 60%; Mixture preparation: Take 1000g of standard sand, put it into the mixer, and immediately add 30g of foundry binder after starting the mixer. Mix for 15s and then discharge. Sample preparation: Quickly pour the mixture into the "8" shaped core box, generally by hand molding and smoothing, place it on the core plate, and when the mold opening strength is reached (or greater than) the mold opening strength, open the core box. The molding is complete. Five samples are prepared for each group, each weighing 67g. The samples should be formed within 5 minutes of sand mixing. The prepared samples are then allowed to harden naturally for 24 hours under specified test conditions. For the determination of tensile strength, the sample is placed in the strength testing machine fixture with the four rollers in the fixture against the sample's waist. The handwheel is rotated to gradually apply load until the sample breaks. The tensile strength value can be read directly from the pressure gauge. The strength values ​​of twelve samples are measured, then the maximum and minimum values ​​are removed, and the average of the remaining ten values ​​is taken as the sample strength value. The gas evolution is determined according to the method specified in GB / T 2684, 5.9 "Determination of Gas Evolution and Gas Evolution Rate," at a temperature of 850℃. For collapsibility testing, cylindrical test samples prepared using the above method are used. The sample size is φ12mm × 20mm, with the stress surfaces being the two ends of the cylinder. The samples should be free of dust accumulation, mechanical damage, and other defects. The samples must be acclimated to the test environment for 24 hours.

Claims

1. A method of preparing a low cost foundry binder, characterized by, The method comprises the following steps: The first step is to weigh: 60-65 parts of plant pitch, 30-35 parts of water, and 7-10 parts of anionic emulsifier; The second step is to add the anionic emulsifier into the weighed water to form an emulsifier aqueous solution, and then heat the emulsifier aqueous solution to 50-70 DEG C and add a water glass solution to adjust the pH value to 11-12 to obtain an emulsifier soap solution; the modulus of the water glass solution in the second step is 3.0-3.5; 2. The method of claim 1, wherein the low cost foundry binder is prepared by the steps of: The third step is to mix the plant pitch heated to 100-110 DEG C and the emulsifier soap solution obtained in the second step to obtain an emulsified plant pitch by an emulsification process by using an emulsifier, thereby obtaining a low-cost casting binder.

3. The method of claim 1, wherein the low cost foundry binder is prepared by the steps of: The emulsifier in the third step is a colloid mill or a high-speed shearing oil homogenizer.

4. The method of claim 1, wherein the low cost foundry binder is prepared by the steps of: The anionic emulsifier in the second step is one of an anionic fast-cracking fast-setting emulsifier, an anionic slow-cracking fast-setting emulsifier, and an anionic slow-cracking slow-setting emulsifier.

5. The method of claim 1, wherein the low cost foundry binder is prepared by the steps of: The plant pitch in the first step is a plant pitch with a penetration of 60-100 at 25 DEG C, 5 s, and 100 g. The emulsification process in the third step is an emulsification process with an emulsification speed of 4000-5000 r / min and an emulsification time of 4-6 min.