CN113426941B - Grinding-aid synergist for casting bentonite and preparation method thereof - Google Patents
Grinding-aid synergist for casting bentonite and preparation method thereof Download PDFInfo
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- CN113426941B CN113426941B CN202110785129.8A CN202110785129A CN113426941B CN 113426941 B CN113426941 B CN 113426941B CN 202110785129 A CN202110785129 A CN 202110785129A CN 113426941 B CN113426941 B CN 113426941B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
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Abstract
The invention provides a grinding-aid synergist for cast bentonite and a preparation method thereof, and the grinding-aid synergist comprises a polyhydroxy benzoate compound and a carrier, wherein the polyhydroxy benzoate compound is one or more of 2, 3-dihydroxybenzoate, 3, 4-dihydroxybenzoate, 2, 6-dihydroxybenzoate, 2, 5-dihydroxybenzoate, 2, 4-dihydroxybenzoate, 3, 5-dihydroxybenzoate, 2,4, 6-trihydroxybenzoate, 3,4, 5-trihydroxybenzoate and 2,3, 4-trihydroxybenzoate; the carrier is bentonite modified by sodium treatment. The grinding-aid synergist for the casting bentonite is an auxiliary agent with the functions of adsorption, dispersion, hydration assistance and the like, can effectively improve the bonding strength of the casting bentonite to casting molding sand, improve the blue absorption amount of the casting bentonite, improve the reusability of the casting bentonite, can also improve the grinding yield of the casting bentonite, and can simultaneously use the bentonite with low blue absorption amount for the production of the casting bentonite and effectively save the production cost.
Description
Technical Field
The invention belongs to the technical field of inorganic non-metallic material production, relates to an additive in casting bentonite production, and particularly relates to a grinding aid synergist for casting bentonite and a preparation method thereof.
Background
Along with the continuous consumption of bentonite resources, the raw soil with high blue absorption amount, which can meet the quality requirement of the cast bentonite, is less and less, so that an additive which can effectively utilize the bentonite resources with low blue absorption amount, can meet the technical indexes of the cast bentonite, save the production cost and increase the production efficiency of the cast bentonite is needed to be found.
The bentonite grinding is a necessary process for producing casting bentonite, and mechanical method is adopted to make bentonite fine, which is a physical and physical-chemical change process of particle size and the like. In the process of crushing bentonite by colliding with grinding media and the like, chemical bonds in particles are cut off, so that charge units are formed, static electricity is generated, the particles are easy to agglomerate again or adsorb on the surface of the media, and the phenomenon of pasting and grinding occurs.
The accumulation of the bentonite powder in the mill is mainly caused by the grinding of the cut particlesThe chemical bond has the function of Si-O bond, bond energy 443.8kJ/mol, al-O bond and bond energy 512kJ/mol, and during grinding, the breaking of grains occurs on Si-O ionic bond and Al-O valence bond greatly, and because of the breaking of chemical bond, great amount of Si appears on two sides of the fracture surface 4+ 、Al 3+ And O 2- When no foreign ions or molecules shield the active points, the active points attract each other to enable the fracture sections to tend to be compounded, the impact effect of the grinding roller and the grinding ring on the fractured particles can not only generate new fractures, but also compact the particles to promote the recombination of the new fractures, one of the effects of the grinding aid is to provide the foreign ions or molecules to neutralize the unsaturated electrovalence on the fracture surface to enable the unsaturated electrovalence to reach saturation, eliminate or weaken the agglomeration tendency of the powder and prevent the recombination of the unsaturated electrovalence. Thus, the use of a grinding aid can significantly improve bentonite grinding efficiency, including yield increase and particle size reduction.
However, when the bentonite product prepared by using the common mineral grinding aid such as amines, ethanolamines, alcohols, polyols and the like for bentonite powder grinding is used for molding sand, the bentonite product is adsorbed at the broken bond position at the end part of the montmorillonite by using adsorptive groups such as amino groups, hydroxyl groups and the like in molecules, and nonpolar groups of the bentonite product point to the external space, so that the hydrophobicity of montmorillonite particles is increased, the water absorption rate is reduced, the hydration rate and the expansion degree of the bentonite particles dispersed in the molding sand are reduced, the bonding effect cannot be fully exerted, and the strength of the molding sand is reduced as a result. Therefore, although the traditional mineral grinding aid can improve the grinding efficiency yield and fineness of the cast bentonite, the traditional mineral grinding aid is not adopted to produce and process the cast bentonite.
Disclosure of Invention
In order to solve the technical problems, the invention provides a grinding aid synergist for casting bentonite and a preparation method thereof. The bentonite is easy to adsorb on the surface of the bentonite material and between new gaps, prevents new gaps from recombining, reduces mutual condensation among the material particles, reduces the interfacial tension of the material, simultaneously plays a role in reducing friction lubrication, improves the crushing effect, improves the dispersibility and the fluidity of the material in the mill, can improve the proportion of particles below 2 micrometers in the cast bentonite, and can obviously improve mechanical indexes such as the bonding strength of the cast bentonite by fine particles. Meanwhile, the grinding aid synergist for the casting bentonite can effectively improve the bonding strength of the casting bentonite to casting molding sand, improve the blue absorption amount of the casting bentonite and improve the reusability of the casting bentonite, can also improve the grinding yield of the casting bentonite, and can effectively save the production cost by using the bentonite with low blue absorption amount for the production of the casting bentonite.
The technical problem to be solved by the invention is realized by the following technical approaches:
a grinding-aid synergist for cast bentonite comprises a polyhydroxy benzoate compound and a carrier, wherein the polyhydroxy benzoate compound is one or more of 2, 3-dihydroxy benzoate, 3, 4-dihydroxy benzoate, 2, 6-dihydroxy benzoate, 2, 5-dihydroxy benzoate, 2, 4-dihydroxy benzoate, 3, 5-dihydroxy benzoate, 2,4, 6-trihydroxy benzoate, 3,4, 5-trihydroxy benzoate and 2,3, 4-trihydroxy benzoate; the carrier is bentonite modified by sodium treatment.
The structural features of the polyhydroxyformate compound are as follows: firstly, the molecule contains at least two hydroxyl groups which are adsorptive groups and can be adsorbed at positive sites exposed by broken bonds at the end parts of montmorillonite particles or form hydrogen bonds and electrostatic adsorption with exposed O atoms of Si-O or Al-O, and the adsorption effect of the hydroxyl groups is far greater than that of strong polar groups such as carboxyl groups, sulfonic groups and the like. The presence of polyhydroxy groups greatly increases the adsorption probability and the adsorption strength, and particularly, the presence of ortho-hydroxyl groups enhances the adsorption. The direct effect of the adsorption is to obviously improve the dispersion degree, fineness and grinding efficiency of the bentonite particles, and the indirect effect is to enhance the hydration degree of the bentonite particles. Secondly, the molecules of the bentonite contain carboxylate groups which are strong hydration groups, the water binding capacity of the bentonite is far greater than that of adsorptive groups such as hydroxyl groups, and the like, and a large number of water molecules can be combined, so that the hydration film thickness of montmorillonite particles is greatly improved. Thirdly, the strong adsorption effect on the montmorillonite particles is beneficial to the carboxylic acid salt groups to play a role in enhancing the hydration effect of the montmorillonite particles. Fourthly, the main body of the molecular structure is a benzene ring, and the benzene ring is heat-resistant, and more importantly, the residual carbon content in the high-temperature decomposition product is the highest except polycyclic aromatic hydrocarbon. This is very good for the reusability of the casting bentonite after high temperature, and can obviously improve the content of the effective bentonite after high temperature heating, namely, the reusability of the casting bentonite is improved. And the carbon film formed on the surface of the casting sand mold by the residual carbon is also beneficial to improving the surface smoothness and the yield of the casting. In conclusion, the high-adsorbability hydroxyl and high-hydration carboxylate groups contained in the molecules of the polyhydroxy sodium benzoate compound as well as the ring structure of the grinding aid synergist for the casting bentonite lead to the unique properties of the grinding aid synergist for the casting bentonite and the application of casting modeling. The requirements of the traditional mineral processing industry on grinding aids such as fatty amines, ethanolamines, alcohols, fatty acids, surfactants and the like are that the grinding aids have enough adsorption capacity with processed minerals so as to change the dispersibility of materials in the mill and eliminate the phenomena of electrostatic adsorption and coating ball and pasting grinding of fine mineral particles. Therefore, the molecules of the traditional grinding aids only contain adsorption groups such as amino, hydroxyl and the like, and do not need or need to contain hydration groups, which is the most important difference in the structure of the cast bentonite grinding aid synergist and the traditional grinding aids.
The carrier is not an inert carrier, and the main function of the carrier is to serve as a carrier of polyhydroxy benzoate, and the polyhydroxy benzoate are uniformly mixed with each other, so that the polyhydroxy benzoate can be uniformly dispersed in bentonite subjected to sodium treatment in the subsequent casting bentonite preparation process. In addition, the carrier is bentonite modified by sodium modification, and still has a binding effect on the molding sand. Namely, the non-inert carrier in the invention does not influence the quality of the casting bentonite and does not have adverse effect.
The mass ratio of the polyhydroxy benzoate compound to the carrier is 1.
Preferably, the polyhydroxy benzoate compound is a polyhydroxy benzoate having an ortho-hydroxyl group in the molecule, such as 2, 3-dihydroxybenzoate, 3,4, 5-trihydroxybenzoate, and 2,3, 4-trihydroxybenzoate. The adsorption effect of two or three of the polyhydroxy benzoate with the ortho-hydroxyl groups on the ends of the montmorillonite particles is obviously stronger than that of polyhydroxy benzoate with non-ortho-hydroxyl groups, and is even stronger than that of benzoate with only one hydroxyl group, so that the polyhydroxy benzoate has better dispersion effect on the cast bentonite, and the carboxylic acid salt groups in the structure can play a role in enhancing the hydration effect of the montmorillonite particles due to the adsorption effect (only on the montmorillonite particles).
The polyhydroxy benzoate is soluble salt, and is sodium salt, potassium salt or ammonium salt. Furthermore, the polyhydroxy benzoate is sodium salt, and the sodium salt is more favorable for improving the expansibility of the casting bentonite and is favorable for the wet compression strength and the hot wet tensile strength of the casting bentonite.
The invention also provides a preparation method of the grinding aid synergist for the casting bentonite, wherein the polyhydroxy benzoate compound and the carrier are uniformly mixed to obtain the grinding aid synergist for the casting bentonite.
The invention also provides a use method of the casting bentonite grinding-aid synergist, which comprises the steps of grinding the casting bentonite grinding-aid synergist and bentonite modified by sodium treatment to obtain casting bentonite; the bentonite is bentonite with high blue absorption amount or mixed bentonite with low blue absorption amount and high blue absorption amount, and the mass percentage of the bentonite with low blue absorption amount in the mixed bentonite with low blue absorption amount and high blue absorption amount is 10-30%; the mass of the polyhydroxy benzoate compound in the added cast bentonite grinding aid synergist is 0.1-0.3% of the mass of the added bentonite modified by sodium treatment.
In order to achieve a better synergistic effect, an auxiliary material is preferably added in the grinding process, and the mass of the added auxiliary material is 0.01-0.1% of the total mass of the added bentonite modified by sodium modification. The auxiliary material is selected from any one or a mixture consisting of more than one of the following substances: sodium carboxymethyl cellulose, calcium lignosulfonate, sodium polyacrylate, polyacrylamide, polyvinyl acetate, sodium humate, polyvinyl alcohol, polyoxyethylene, hydroxyethyl cellulose, light calcined powder, magnesium oxide and the like, wherein auxiliary materials are mixed after casting bentonite is ground. The auxiliary material is widely used in casting bentonite, and is not taken as a special item of the invention.
The beneficial effects of the invention are:
1. obviously improve the bonding strength of the casting bentonite
The main component of the grinding aid reinforcing agent for casting bentonite is an aromatic compound containing a plurality of hydroxyl groups and carboxylate groups, the compound with the structure is used for bentonite products obtained by grinding bentonite powder, in the sand mixing and forming process, the adjacent hydroxyl groups of the compound are used as adsorption groups to be adsorbed at the end parts of montmorillonite particles in the bentonite, and meanwhile, the carboxylate groups of the compound point to the external space. The carboxylate groups are strong hydration groups, the water binding capacity is very strong, the hydration rate of bentonite particles is greatly improved due to the existence of the carboxylate groups, the hydration film thickness of montmorillonite particles is increased, the hydration of the montmorillonite particles is more sufficient, the expansion volume is larger, the bonding effect of the montmorillonite particles in the molding sand is more fully exerted, and the mechanical strength of the molding sand, such as the wet compression strength, the hot wet tensile strength and the like, is improved. The strong adsorption effect on the montmorillonite particles is beneficial to the carboxyl to play a role in enhancing the hydration effect of the montmorillonite particles.
2. Stripping to remove impurities and improve the index of blue absorption of casting bentonite
The grinding aid synergist for the casting bentonite is the same as the traditional mineral grinding aid, and can also obviously improve the grinding efficiency of the bentonite, including the improvement of yield and the reduction of granularity. It is known that natural bentonite minerals contain, in addition to montmorillonite, opal, cristobalite, quartz, illite, mica, zeolite, chlorite, feldspar and other impurities, the total amount of which is generally 30 to 50% or even higher. These impurities tend to be encapsulated in the montmorillonite crystals as very fine particles. If the milled cast particles are coarse, the majority of these impurities will still be encapsulated in the montmorillonite crystals and certainly not separated from the bentonite in the desander. After the bentonite grinding aid synergist is used, bentonite can be ground to be fine enough under the condition of not increasing energy consumption, the thickness of montmorillonite particles is generally below 5 crystal layers, and the thickness is far smaller than the thickness of 10-15 crystal layers of standard fineness 200 meshes of bentonite particles produced by not using the bentonite grinding aid synergist. That is, the cast bentonite processed by the cast bentonite grinding aid synergist of the invention can ensure that montmorillonite crystal layers are stripped more fully, impurities contained in the montmorillonite crystals are stripped more fully, and the impurities are separated out in a following desander because the density of the impurities is higher than that of the montmorillonite, so that the montmorillonite content and the blue absorption amount in the produced cast bentonite are improved, namely the purity of the cast bentonite is improved.
The reduction of the granularity of the casting bentonite and the improvement of the blue absorption amount are also beneficial to the improvement of the bonding strength of the casting bentonite, namely the grinding aid synergist for the casting bentonite can obviously improve the wet-pressing strength and the hot-wet tensile strength of the casting bentonite. The cast bentonite grinding-aid synergist is a yellowish-brown powder, and industrial experiments prove that the product has good grinding-aid and synergistic effects on bentonite with low blue absorption and high blue absorption. Particularly, the bentonite with low blue absorption amount widely existing in the nature can be used for the production and processing of the casting bentonite, which has great significance for fully utilizing the bentonite resource and reducing the production cost of the casting bentonite.
3. Improving reusability of casting bentonite
The casting bentonite produced by the casting bentonite grinding aid synergist is used for manufacturing a molding sand model, and when molten iron is poured into the molding sand model, grinding aid synergist molecules on the surface layer of the sand model are decomposed under the high-temperature action of the molten iron. As the main body of the grinding aid synergist is a benzene ring structure, the residual carbon rate of pyrolysis products is very high, so that the concentration of carbon in pyrolysis steam of the grinding aid synergist is very high, and the steam is diffused into a sand mold under the high-temperature action of molten iron and is rapidly condensed on the surfaces of montmorillonite and sand grains on the inner layer to form a carbon isolation layer. The isolation layer of carbon is not a good thermal conductor, so that thermal shock of molten iron on montmorillonite in the sand mould at high temperature can be reduced, the heating temperature is reduced to a certain extent, and montmorillonite particles are protected. That is, the thermal resistance of the carbon isolation film layer formed by carbon vapor generated by the thermal decomposition of grinding aid synergists such as 3,4, 5-trihydroxy sodium benzoate and the like reduces the ablation rate of the montmorillonite in the sand mold, increases the ratio of the residual montmorillonite, and further improves the reusability of the casting bentonite. Meanwhile, the ablation rate of the montmorillonite in the sand mould is reduced, so that the content reduction of the montmorillonite for maintaining the bonding strength of the sand mould at high temperature is reduced, and the hot wet tensile strength of the sand mould is also improved to a certain extent.
In conclusion, the grinding aid reinforcing agent for the cast bentonite is a special additive applied to the production of the cast bentonite, the grinding aid reinforcing agent improves the grinding efficiency, the bonding strength and the reusability of the cast bentonite by adopting a physical and chemical principle, the using amount of the bentonite with high blue absorption can be greatly saved after the grinding aid reinforcing agent is added, the utilization rate of the low-quality bentonite is increased, and therefore the production cost of the cast bentonite is reduced and the resource utilization rate of the bentonite is improved. The grinding-aid synergist for the casting bentonite is used for grinding the casting bentonite, so that the grinding efficiency is greatly improved, and the proportion of fine particles is increased, so that the bonding capacity of the bentonite is improved.
All raw materials used in the invention are of industrial grade.
Taking a casting bentonite enterprise producing 10 ten thousand tons per year as an example, after the casting bentonite is produced and mixed with 0.2 percent of the grinding aid reinforcing agent (calculated by sodium polyhydroxybenzoate), the cost saving is calculated as follows (the high-quality bentonite is calculated according to 150 yuan/ton, and the low-quality bentonite is calculated according to 50 yuan/ton):
if the dosage of the high blue absorption bentonite is reduced by 25 percent, the low blue absorption bentonite is increased by 24.8 percent.
Then cost is saved per ton: high blue absorption bentonite unit price multiplied by 25 percent, low blue absorption bentonite unit price multiplied by 24.8 percent, grinding aid reinforcing agent unit price multiplied by 0.2 percent (= 150 multiplied by 25 percent to 50 multiplied by 24.8 percent to 8000 multiplied by 0.2 percent (= 9.1 yuan/ton).
The cost is saved all the year around =10 ten thousand tons multiplied by 9.1 yuan/ton =91 ten thousand yuan
The analysis shows that after an enterprise producing 10 million tons of casting bentonite every year uses the grinding aid reinforcing agent, 91 million yuan of cost can be saved every year, the economic benefit is considerable, and the saving does not need to change any process and flow of the original casting bentonite production.
In addition, the cast bentonite grinding aid reinforcing agent also has the following beneficial effects:
1. improving strength grade of casting bentonite
0.1-0.3% of the grinding aid reinforcing agent is doped, so that mutual agglomeration among bentonite particles is reduced, the crushing effect is improved, the proportion of particles below 2 microns can be improved, and the thickness of a hydrated film of montmorillonite particles is increased, so that the wet compression strength and the hot wet tensile strength of cast bentonite can be remarkably improved.
2. Increase the output of Raymond mill
The cast bentonite grinding aid synergist is easily adsorbed on the surface and among gaps of bentonite materials, so that the interfacial tension of the materials is reduced, friction is reduced, mutual agglomeration among the materials is reduced, the grinding phenomenon is reduced, and the grinding effect is improved. Namely, after the grinding-aid synergist is doped, the bentonite can be more easily ground into fine particles, the output per hour of a Raymond mill can be improved, and the power consumption in the production of unit casting bentonite is correspondingly reduced.
3. Improve the utilization rate of bentonite resources
Because the grinding aid synergist can effectively improve the bonding strength index of the casting bentonite, a certain amount of low blue absorption bentonite can be doped under the condition of using the casting bentonite grinding aid synergist, the doping proportion can be determined according to the quality of the high and low blue absorption bentonite and the strength requirement of the casting bentonite, generally, 10-30% of the low blue absorption bentonite can be doped into each ton of the casting bentonite by mass fraction, and the grinding aid synergist has the effects of good environmental protection and improvement of the utilization of bentonite resources.
The casting bentonite grinding-aid synergist is very simple and convenient to use, when the casting bentonite is ground, 0.1-0.3% of the casting bentonite grinding-aid synergist (calculated by hydroxybenzoate) is added, the use of high blue-absorption bentonite can be reduced, the low blue-absorption bentonite is used for substitution, and the substitution proportion can be determined according to the quality of the high blue-absorption bentonite and the low blue-absorption bentonite and the strength requirement of the casting bentonite.
Detailed Description
The features and benefits of the present invention are further described below by way of examples, which should be construed as merely illustrative, and not a limitation of the scope of the invention.
Example 1: preparation of the grinding-aid reinforcing agent for casting bentonite
(1) The casting bentonite grinding aid synergist A is prepared by uniformly mixing a polyhydroxy sodium benzoate mixture consisting of 2, 4-dihydroxy sodium benzoate, 3, 5-dihydroxy sodium benzoate and 2,4, 6-trihydroxy sodium benzoate in equal mass ratio with bentonite modified by sodium treatment according to the mass ratio of 1.
(2) The casting bentonite grinding aid synergist B is obtained by uniformly mixing a polyhydroxy sodium benzoate mixture consisting of 3,4, 5-trihydroxy sodium benzoate and 2,3, 4-trihydroxy sodium benzoate with the same mass with casting bentonite according to the mass ratio of 1.
(3) And (3) uniformly mixing 2,3, 4-trihydroxy sodium benzoate and the cast bentonite according to the mass ratio of 1.
Example 2: application of grinding-aid synergist for cast bentonite in high blue absorption bentonite effect test
A first group: the casting bentonite comprises the following raw materials (percent): adding solid Na accounting for 4 percent of the mass of the bentonite into 100 percent of the bentonite with the blue absorption amount of 34 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, extruding for sodium treatment, drying until the water content is below 12 percent, and grinding for 15min to obtain a casting bentonite sample I.
Second group: the casting bentonite comprises the following raw materials (percent): 100 percent of bentonite with the blue absorption amount of 34, and solid Na with the mass of 4 percent of the bentonite is added 2 CO 3 Spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding the casting bentonite grinding aid reinforcing agent A prepared in the example 1, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2 percent of the mass of the sodium treatment modified bentonite, and grinding for 15min to obtain a casting bentonite sample II.
The wet-compressive strength, hot-wet tensile strength and the amount of residue on sieve were measured according to the specification of JB/T9227-2013 "cast Bentonite", and the results are shown in Table 1.
TABLE 1 application effect of grinding-aid synergist for casting bentonite on high blue absorption bentonite
It can be seen from table 1 that the grinding aid synergist a of the present invention can improve the wet compressive strength and hot wet tensile strength of high blue absorbing bentonite by 15kPa and 0.3kPa, respectively. Meanwhile, the grinding aid reinforcing agent can also obviously reduce the granularity of products. The grinding aid synergist of the invention is beneficial to the bonding strength of the bentonite with high blue absorption and the reduction of particle size.
Example 3: application of grinding-aid synergist for casting bentonite in low blue absorption bentonite effect test
Third group: the casting bentonite comprises the following raw materials (percent): 100 percent of bentonite with blue absorption amount of 18, and then solid Na accounting for 4 percent of the mass of the bentonite is added 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, and grinding for 15min to obtain a third cast bentonite sample.
And a fourth group: the raw material proportion for producing the casting bentonite is as follows (%): 100 percent of bentonite with the blue absorbing amount of 18, and then solid Na with the mass of 4 percent of the bentonite is added 2 CO 3 Spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding the casting bentonite grinding aid reinforcing agent A prepared in the example 1, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2 percent of the mass of the sodium modified bentonite, and grinding for 15min to obtain a casting bentonite sample IV.
The wet-compressive strength, hot-wet tensile strength and particle size were measured as specified in JB/T9227-2013 "cast Bentonite", and the results are shown in Table 2.
TABLE 2 application effect of grinding-aid synergist for casting bentonite on low blue absorption bentonite
| Sample number | Sample No. three | Sample No. 4 |
| Wet compressive strength/kPa | 38 | 52 |
| Hot wet tensile strength/kPa | 0.7 | 1.0 |
| 200 mesh sifting/%) | 3.7 | 0.6 |
It can be seen from table 2 that the grinding aid synergist a of the present invention can improve the wet compressive strength and hot wet tensile strength of low blue absorbing bentonite by 14kPa and 0.3kPa, respectively. Meanwhile, the grinding aid synergist can also obviously reduce the granularity of products. The grinding aid synergist of the invention is also beneficial to improving the bonding strength and the fine particle content of the bentonite with low blue absorption.
Example 4: the casting bentonite grinding aid synergist is used for increasing the low blue absorption bentonite mixing amount effect test fifth group: the raw materials for producing the casting bentonite comprise the following components (%): 80 percent of bentonite with 34 percent of blue absorption amount, 20 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 Is mixed bySpraying water in the process to enable the water content in the bentonite to be about 30%, carrying out extrusion sodium treatment, drying until the water content is below 12%, adding the casting bentonite grinding aid reinforcing agent B prepared in the first embodiment, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2% of that of the sodium modified bentonite, and grinding for 15min to obtain a fifth casting bentonite sample.
A sixth group: the raw material proportion for producing the casting bentonite is as follows (%): 70 percent of bentonite with 34 percent of blue absorption amount, 30 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30%, performing extrusion sodium treatment, drying until the water content is below 12%, adding the cast bentonite grinding aid reinforcing agent B prepared in the first embodiment, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2% of that of the sodium modified bentonite, and grinding for 15min to obtain a sixth cast bentonite sample.
A seventh group: the raw material proportion for producing the casting bentonite is as follows (%): 60 percent of bentonite with 34 percent of blue absorption amount and 40 percent of bentonite with 18 percent of blue absorption amount, and then solid Na with 4 percent of the mass of the bentonite is added 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding the cast bentonite grinding aid reinforcing agent B prepared in the first embodiment, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2 percent of that of the sodium modified bentonite, and grinding for 15min to obtain a cast bentonite sample seven.
And an eighth group: the raw material proportion for producing the casting bentonite is as follows (%): 50 percent of bentonite with 34 percent of blue absorption amount and 50 percent of bentonite with 18 percent of blue absorption amount, and then solid Na with 4 percent of the mass of the bentonite is added 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30%, performing extrusion sodium treatment, drying until the water content is below 12%, adding the cast bentonite grinding aid reinforcing agent B prepared in the first embodiment, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2% of that of the sodium modified bentonite, and grinding for 15min to obtain a cast bentonite sample eight.
Ninth group: the raw material proportion for producing the casting bentonite is as follows (%): 50 percent of bentonite with the blue absorption of 34 percent,50 percent of bentonite with the blue absorption amount of 18, and then solid Na with the mass of 4 percent of the bentonite is added 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, and grinding for 15min to obtain a casting bentonite sample nine.
The wet-pressure strength, hot-wet tensile strength and particle size of the cast bentonite were determined according to the specifications of GB/T20973-2007 Bentonite, and the results are shown in Table 3.
TABLE 3 application effect of grinding-aid synergist for cast bentonite on composite bentonite
| Sample number | Sample five | Sample six | Sample seven | Sample eight | Sample No. nine |
| Wet compressive strength/kPa | 114 | 92 | 67 | 41 | 37 |
| Hot wet tensile strength/kPa | 2.7 | 2.1 | 1.5 | 0.4 | 0.3 |
As can be seen from Table 3, the addition of 0.2% of the grinding aid synergist B for casting bentonite of the invention can greatly improve the addition amount of the low blue absorption bentonite. If the wet compression strength and the hot wet tensile strength of the bentonite mixture doped with 20 percent of bentonite with low blue absorption amount in the sample five reach 1 grade respectively; after 30% of bentonite with low blue absorption is doped in the sixth sample, the wet compression strength and the hot wet tensile strength reach 2 grades; after 40% of bentonite with low blue absorption is doped in the sample seven, the wet compression strength and the hot wet tensile strength reach grade 3; after the bentonite with low blue absorption amount of 50% is doped into the samples eight and nine, the wet compression strength reaches 4 grades and the hot wet tensile strength does not reach the requirement of the lowest standard (4 grades) in GB/T20973-2007 Bentonite regardless of whether the grinding aid synergist is used.
The minimum requirements of a general foundry on the wet-pressure strength and the hot-wet tensile strength of the cast bentonite are 2 grades, namely the wet-pressure strength is more than or equal to 70kPa, and the hot-wet tensile strength is more than or equal to 2.0kPa. Thus, for the two different blue absorbing amounts (34 and 18) of bentonite used in the examples of the present invention, a low blue absorbing amount of bentonite having 30% blue absorbing amount 18 can be incorporated.
Example 5: contrast effect experiment of casting bentonite grinding aid synergist and traditional grinding aids such as triethanolamine
A tenth group: the raw materials for producing the casting bentonite comprise the following components (%): 80 percent of bentonite with blue absorption of 34 percent, 20 percent of bentonite with blue absorption of 18 percent, and solid Na which accounts for 4 percent of the mass of the bentonite are added 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding the casting bentonite grinding aid reinforcing agent C prepared in the first embodiment, wherein the mass of the sodium 2,3, 4-trihydroxybenzoate is 0.2 percent of the mass of the sodium modified bentonite, and grinding for 15min to obtain a casting bentonite sample ten.
Eleventh group: the raw material proportion for producing the casting bentonite is as follows (%): 80% of bentonite with blue absorption of 34%, 20% of bentonite with blue absorption of 18%, and adding bentoniteSolid Na accounting for 4 percent of the mass of the soil 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding chemical pure triethanolamine accounting for 0.2 percent of the mass of the sodium-treated modified bentonite, and grinding for 15min to obtain an eleventh cast bentonite sample.
A twelfth group: the raw material proportion for producing the casting bentonite is as follows (%): 80 percent of bentonite with blue absorption of 34 percent, 20 percent of bentonite with blue absorption of 18 percent, and solid Na which accounts for 4 percent of the mass of the bentonite are added 2 CO 3 Spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding chemical pure sodium ortho-hydroxybenzoate with the mass of 0.2 percent of the sodium treatment modified bentonite, and grinding for 15min to obtain a twelve-sample cast bentonite.
Group thirteen: the raw material proportion for producing the casting bentonite is as follows (%): 80 percent of bentonite with 34 percent of blue absorption amount, 20 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 Spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, adding chemical pure sodium benzoate accounting for 0.2 percent of the mass of the sodium-treated modified bentonite, and grinding for 15min to obtain a casting bentonite sample thirteen.
The wet-pressure strength, hot-wet tensile strength and particle size of the cast bentonite were determined according to the GB/T20973-2007 Bentonite, and the results are shown in Table 4.
TABLE 4 application effect of grinding-aid synergist for casting bentonite on composite bentonite
As can be seen from the table 4, after 0.2 percent of the grinding aid synergist of the invention is added, the wet compression strength and the hot wet tensile strength of the bentonite mixture respectively reach grade 1; eleven samples of triethanolamine which are taken as a traditional grinding aid only reach the grade 3 standard in strength. The samples twelve are respectively doped with sodium ortho-hydroxybenzoate with only one hydroxyl group in the molecule, and the strength just reaches the hot wet tensile strength 2-level standard. Sample thirteen was spiked with sodium benzoate without hydroxyl groups, and its strength only reached the fourth-order standard.
The grinding aid synergist for the cast bentonite, which contains two or more hydroxyl benzoate in the molecule, is greatly different from the benzoate containing no or only one hydroxyl in the molecule, and the traditional mineral grinding aid has different effects with montmorillonite in the bentonite, and can help both grinding and synergism.
Example six: experiment for influence of grinding-aid synergist of casting bentonite and traditional grinding-aid triethanolamine on reusability of casting bentonite
A fourteenth group: the raw materials for producing the casting bentonite comprise the following components (%): 80 percent of bentonite with 34 percent of blue absorption amount, 20 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30 percent, carrying out extrusion sodium treatment, drying until the water content is below 12 percent, and grinding for 15min to obtain a fourteen-sample cast bentonite.
A fifteenth group: the raw materials for producing the casting bentonite comprise the following components (%): 80 percent of bentonite with 34 percent of blue absorption amount, 20 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 And spraying water in the mixing process to ensure that the water content in the bentonite is about 30%, performing extrusion sodium treatment, drying until the water content is below 12%, adding the cast bentonite grinding aid reinforcing agent A prepared in the first embodiment, wherein the mass of the sodium polyhydroxy benzoate mixture is 0.2% of that of the sodium treated modified bentonite, and grinding for 15min to obtain a cast bentonite sample fifteen.
Sixteenth group: the raw material proportion for producing the casting bentonite is as follows (%): 80 percent of bentonite with 34 percent of blue absorption amount, 20 percent of bentonite with 18 percent of blue absorption amount, and solid Na which is 4 percent of the mass of the bentonite 2 CO 3 And spraying water in the mixing process to enable the water content in the bentonite to be about 30%, performing extrusion sodium treatment, drying until the water content is below 12%, adding chemical pure triethanolamine accounting for 0.2% of the mass of the sodium-treated modified bentonite, and grinding for 15min to obtain a sixteen-sample cast bentonite.
The reusability of cast bentonite was determined according to GB/T20973-2007 Bentonite, and the results are shown in Table 5.
TABLE 5 Experimental results of reusability of casting bentonite grinding aid synergist to composite bentonite
| Sample number | Fourteen samples | Fifteen samples | Sixteen samples |
| Multiplexing/%) | 22.7 | 25.4 | 22.5 |
The experimental results in table 5 show that the steam with high carbon residue rate generated by pyrolysis of the grinding aid synergist with the main structure of benzene ring is condensed on the surface of the montmorillonite particle in the inner layer to form a carbon isolation layer, so that the steam has a certain inhibition effect on molten iron high temperature, the ablation rate of the montmorillonite is reduced, and the reusability of casting bentonite is improved. This effect is not seen with the traditional grinding aid triethanolamine.
The cast bentonite strength index rating in GB/T20973-2007 Bentonite is shown in Table 6:
TABLE 6 GB/T20973-2007 Bentonite cast Bentonite Strength index
| Item | First stage | Second order | Three-stage | Four stages |
| Wet pressure strength/kPa not less than | 100 | 70 | 50 | 30 |
| Hot wet tensile strength/kPa not less than | 2.5 | 2.0 | 1.5 | 0.5 |
Claims (4)
1. A use method of a grinding-aid synergist for casting bentonite is characterized by comprising the following steps: grinding the casting bentonite grinding aid synergist and the bentonite modified by sodium treatment to obtain casting bentonite; the mass of the polyhydroxy benzoate compound in the added cast bentonite grinding aid synergist is 0.1-0.3% of that of the added sodium modified bentonite; the bentonite is bentonite with high blue absorption amount or mixed bentonite with low blue absorption amount and high blue absorption amount, and the mass percentage of the bentonite with low blue absorption amount in the mixed bentonite with low blue absorption amount and high blue absorption amount is 10-30%; the casting bentonite grinding-aid synergist comprises a polyhydroxy benzoate compound and a carrier, wherein the polyhydroxy benzoate compound is one or more of 2, 3-dihydroxy benzoate, 3, 4-dihydroxy benzoate, 2, 6-dihydroxy benzoate, 2, 5-dihydroxy benzoate, 2, 4-dihydroxy benzoate, 3, 5-dihydroxy benzoate, 2,4, 6-trihydroxy benzoate, 3,4, 5-trihydroxy benzoate and 2,3, 4-trihydroxy benzoate; the carrier is bentonite modified by sodium treatment; the mass ratio of the polyhydroxy benzoate compound to the carrier is 1; and uniformly mixing the polyhydroxy benzoate compound and the carrier to obtain the casting bentonite grinding aid synergist.
2. The method of using a foundry bentonite grinding aid synergist as recited in claim 1, wherein: the polyhydroxy benzoate compound is polyhydroxy benzoate with ortho-hydroxyl in molecules.
3. The method of using a foundry bentonite grinding aid synergist as recited in claim 1, wherein: the polyhydroxy benzoate is sodium salt, potassium salt or ammonium salt.
4. The method of using a cast bentonite grinding aid synergist according to claim 1, wherein: and auxiliary materials are also added in the grinding process, and the mass of the added auxiliary materials is 0.01-0.1% of that of the sodium modified bentonite.
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