A geopolymer material based on magnesium slag, alkali slag and Yellow River sediment and its preparation method

Abstract

The present invention belongs to the field of new materials, and discloses a geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, and a preparation method thereof. The geopolymer material comprises the following raw materials in parts by weight: 40 to 60 parts of magnesium slag, 5 to 10 parts of alkali slag, 26 to 45 parts of Yellow River sediment, 2 to 5 parts of geopolymer activator, 0.5 to 2 parts of inorganic reinforcing whiskers, 1 to 2 parts of dispersant, 0.5 to 1 part of surfactant, and 15 to 20 parts of water. The preparation method comprises: adding the geopolymer activator, the inorganic reinforcing whiskers, the dispersant, and the surfactant to water in sequence and mixing to obtain a mixed solution; adding magnesium slag to the mixed solution and mixing, then adding alkali slag and Yellow River sediment in sequence and mixing, casting and forming, and thus obtaining the geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment. The geopolymer material of the present invention not only has the value of energy conservation, environmental protection, and recycling, but also has good economic and social benefits.

Description

Technical Field

[0001] The present invention relates to the field of new materials, and in particular to a geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, and a preparation method thereof. Background Art

[0002] Geopolymers (geopolymers), a new type of non-cement-based, green, inorganic mortar material, have emerged as a hot topic in recent research. They are considered one of the most promising cement alternatives. Geopolymer production is simple, requiring no high-temperature calcination, significantly reducing energy consumption. Geopolymer production produces approximately 20% of the carbon emissions of cement and produces virtually no harmful gases, essentially achieving zero pollutant emissions. Therefore, geopolymers hold significant significance for achieving sustainable development and green construction in the construction industry.

[0003] Geopolymers are widely available, low-cost, and recycle industrial waste, eliminating the need for significant mineral resource consumption. Magnesium slag, an industrial waste product from the Pidgeon process, contains significant amounts of heavy metals and alkaline oxides. It is estimated that my country produces over 6.5 million tons of magnesium slag annually. Traditionally, the presence of magnesium oxide in magnesium slag often results in poor volume stability in building materials, posing a potential safety hazard.

[0004] The Yellow River carries an average of 1.6 billion tons of sediment annually. This massive amount of sediment accumulates in the riverbed, causing it to rise year after year, to the point where it appears as a "hanging river above ground." Therefore, utilizing Yellow River sediment appropriately can help lower the riverbed, ensure flood safety, and restore the reservoir capacity of water conservancy projects, offering significant economic, environmental, and social benefits. Summary of the Invention

[0005] In view of the problems and shortcomings of the existing technology, the present invention provides a geopolymer material based on the combination of magnesium slag-alkali slag-Yellow River sediment and a preparation method thereof.

[0006] Based on the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a geopolymer material based on the combination of magnesium slag-alkali slag-Yellow River silt, which is prepared from the following raw materials, by mass: 40-60 parts of magnesium slag, 5-10 parts of alkali slag, 26-45 parts of Yellow River silt, 2-5 parts of geopolymer activator, 0.5-2 parts of inorganic reinforcing whiskers, 1-2 parts of dispersant, 0.5-1 part of surfactant, and 15-20 parts of water.

[0008] Furthermore, the magnesium slag is prepared by naturally cooling the reduced slag produced by the Pidgeon process of magnesium smelting, and then crushing and grinding it into powder particles.

[0009] Furthermore, the alkali residue is alkaline white mud particles.

[0010] Furthermore, the alkali slag is made by drying the alkaline white mud produced by the ammonia-alkali industry and then crushing and grinding it into powder particles.

[0011] Furthermore, the drying temperature of the alkaline white mud is 105-115°C.

[0012] Furthermore, the Yellow River silt is made by drying the Yellow River fine sand and then crushing and grinding it into powder particles.

[0013] Furthermore, the drying temperature of the Yellow River sediment is 105-115°C.

[0014] Furthermore, the particle size of the magnesium slag is less than 300 μm, the particle size of the alkali slag is less than 300 μm, and the particle size of the Yellow River sediment is less than 600 μm.

[0015] Preferably, the geopolymer activator is at least one of phosphoric acid and aluminum dihydrogen phosphate.

[0016] Preferably, the inorganic reinforcing whiskers are at least one of short zirconium oxide whiskers, boron nitride whiskers, and silicon carbide whiskers.

[0017] Preferably, the dispersant is at least one of sodium tripolyphosphate and sodium hexametaphosphate.

[0018] Preferably, the surfactant is a sodium salt of polycarboxylate.

[0019] Preferably, the water is deionized water.

[0020] In a second aspect, the present invention provides a method for preparing a geopolymer material based on a combination of magnesium slag, alkali slag and Yellow River sediment, comprising the following steps:

[0021] (1) adding a geopolymer activator, an inorganic reinforcing whisker, a dispersant, and a surfactant to water in sequence and mixing them to obtain a mixed solution;

[0022] (2) Magnesium slag is added to the mixed solution and mixed evenly, and then alkali slag and Yellow River silt are added in turn and mixed evenly, and cast into shape, and sealed and cured at a temperature of 40 to 60°C for 12 to 48 hours to obtain a geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River silt.

[0023] Furthermore, the mixing time of the magnesium slag in step (2) is 2 to 5 minutes.

[0024] Furthermore, the mixing time of the alkali residue and Yellow River sediment in step (2) is 1 to 2 minutes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention makes full use of the free magnesium oxide in the magnesium slag which is difficult to handle and the excess chloride ions in the alkali slag, so that they are mutually solidified during the geopolymerization reaction to generate hydrated magnesium oxychloride gelling material, thereby improving the strength of the geopolymer material.

[0027] 2. The present invention consolidates the free magnesium oxide in the magnesium slag, thereby reducing the hidden danger of poor volume stability of the magnesium slag during its utilization as building materials. At the same time, when utilizing the alkali slag, it simplifies the traditional treatment process of "dechlorination" in the utilization of alkali slag, thereby saving costs and improving production efficiency.

[0028] 3. The present invention uses inorganic reinforcing whiskers to enhance the mechanical properties, thermal stability, wear resistance and corrosion resistance of geopolymer materials, thereby overcoming the disadvantage of large brittleness of geopolymer materials and making its application field more extensive.

[0029] 4. The present invention uses a dispersant to improve the dispersion of the inorganic reinforcing whiskers in the geopolymer material, increase the dispersion degree and dispersion stability of the inorganic reinforcing whiskers, avoid the agglomeration and coagulation of the inorganic reinforcing whiskers and cause them to settle in the geopolymer slurry, thereby improving the overall performance of the geopolymer material.

[0030] 5. The present invention adopts the combined use of magnesium slag-alkali slag-Yellow River sediment to prepare a new type of geopolymer material, which not only makes full use of the huge annual output of industrial solid waste, but also utilizes the excess sediment of the Yellow River, reduces the siltation of the Yellow River, and ensures the flood channel. It not only has the value of energy saving, environmental protection, and recycling, but also has good economic and social benefits. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear and distinct, the present invention is further described in detail below through examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] (1) Magnesium slag exploration experiment

[0033] Example 1

[0034] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment comprises the following components, calculated by mass: 50 parts of magnesium slag, 7 parts of alkali slag, 35 parts of Yellow River sediment, 3.5 parts of phosphoric acid, 1.2 parts of zirconium oxide short whiskers, 1.5 parts of sodium tripolyphosphate, 0.7 part of sodium polycarboxylate, and 17 parts of deionized water.

[0035] The method for preparing the geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment comprises the following steps:

[0036] (1) After the reduction slag produced by the Pijiang process of magnesium smelting is naturally cooled, a jaw crusher and a ball mill are used to crush and grind the reduction slag into powder particles with a particle size of less than 300 μm to obtain magnesium slag; the alkaline white mud produced by the ammonia-soda industry is dried at 110°C in a drum dryer, crushed and ground into powder particles with a particle size of less than 300 μm to obtain alkaline slag; the Yellow River fine sand taken from the Zhengzhou section of the Yellow River is dried at 110°C, crushed and ground into powder particles with a particle size of less than 600 μm to obtain Yellow River sediment;

[0037] (2) 3.5 parts of phosphoric acid, 1.2 parts of zirconium oxide short whiskers, 1.5 parts of sodium tripolyphosphate, and 0.7 parts of sodium polycarboxylate were added to 17 parts of deionized water in sequence, and stirred and mixed using a continuous stirrer to obtain a mixed solution;

[0038] (3) Add 50 parts of magnesium slag to the mixed solution, stir for 3 minutes to mix, then add 7 parts of alkali slag and 35 parts of Yellow River silt in turn, continue stirring for 2 minutes to mix, cast into shape using a mold, and seal and cure at 40°C for 24 hours to obtain a geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River silt.

[0039] Example 2

[0040] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the magnesium slag is 40 parts.

[0041] Example 3

[0042] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the magnesium slag is 60 parts.

[0043] Comparative Example 1

[0044] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the magnesium slag is 30 parts.

[0045] Comparative Example 2

[0046] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the magnesium slag is 70 parts.

[0047] Comparative Example 3

[0048] A geopolymer material, whose composition and preparation method are basically the same as those in Example 1, except that no magnesium slag is added.

[0049] The geopolymer materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested for performance according to the compressive and flexural strength testing methods described in GB / T 17671-2021, "Test Methods for Cement Mortar Strength (ISO Method)"; the chloride ion flux testing method described in GB / T 50082-2009, "Standard for Test Methods for Long-Term Properties and Durability of Ordinary Concrete"; and the 3-hour vertical expansion rate testing method described in JC / T 986-2018, "Cement-Based Grouting Materials." The test results are shown in Table 1.

[0050] Table 1 Effect of magnesium slag dosage on geopolymer material properties

[0051] Group Amount of magnesium slag (parts by mass) Compressive strength (MPa) Flexural strength (MPa) Electric flux (C) 3h vertical expansion rate (%) Example 1 50 47.3 11.2 891 2.7 Example 2 40 41.5 9.8 976 2.1 Example 3 60 45.6 8.3 1011 3.5 Comparative Example 1 30 39.2 9.4 1144 1.7 Comparative Example 2 70 37.9 7.6 1576 5.2 Comparative Example 3 / 28.5 6.2 3391 0.1

[0052] As shown in Table 1, when the magnesium slag dosage is gradually increased from 30 to 70 parts by mass, the compressive strength and flexural strength of the examples and comparative examples first increase and then decrease, the electric flux first decreases and then increases, and the 3-hour vertical expansion rate gradually increases. When the magnesium slag dosage in Example 1 is 50 parts by mass, the compressive strength and flexural strength reach their maximum values ​​of 47.3 MPa and 11.2 MPa, respectively, the electric flux reaches its minimum value of 891°C, and the 3-hour vertical expansion rate reaches 2.7%.

[0053] When the amount of magnesium slag in Comparative Example 1 is too small, the magnesium oxide content in the magnesium slag-alkali residue-Yellow River sediment system is relatively low, and the magnesium oxychloride gel material generated by the geopolymer reaction is relatively low, causing its mechanical properties to decline and the corresponding 3h vertical expansion rate to be relatively small; at the same time, the low magnesium oxide content cannot solidify the excess chloride ions in the alkali residue, causing the electric flux to be relatively large. When the amount of magnesium slag in Comparative Example 2 is too large, the geopolymer reaction cannot consume too much magnesium oxide, and the volume expansion of free magnesium oxide in the already solidified geopolymer material causes internal microcracks, reducing its mechanical properties and improving the electric flux and 3h vertical expansion rate. When magnesium slag is not added in Comparative Example 3, the compressive strength, flexural strength, and 3h vertical expansion rate of the geopolymer material are all minimum values, and the electric flux reaches the maximum value. This shows that the presence of magnesium slag helps to generate gelled substances in the geopolymer system, improve mechanical properties, and solidify chloride ions in the alkali residue.

[0054] (2) Alkali slag exploration experiment

[0055] Example 4

[0056] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the alkali slag is 5 parts.

[0057] Example 5

[0058] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the alkali slag is 10 parts.

[0059] Comparative Example 4

[0060] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the alkali slag is 2 parts.

[0061] Comparative Example 5

[0062] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the alkali slag is 15 parts.

[0063] Comparative Example 6

[0064] A geopolymer material, whose composition and preparation method are basically the same as those of Example 1, except that no alkali residue is added.

[0065] The geopolymer materials prepared in Examples 4-5 and Comparative Examples 4-6 were tested for performance according to the compressive and flexural strength testing methods described in GB / T 17671-2021, "Test Methods for Cement Mortar Strength (ISO Method)"; the chloride ion flux testing method described in GB / T 50082-2009, "Standard for Test Methods for Long-Term Properties and Durability of Ordinary Concrete"; and the 3-hour vertical expansion rate testing method described in JC / T 986-2018, "Cement-Based Grouting Materials." The test results are shown in Table 2.

[0066] Table 2 Effect of alkali residue dosage on geopolymer material properties

[0067] Group Amount of alkali residue (parts by mass) Compressive strength (MPa) Flexural strength (MPa) Electric flux (C) 3h vertical expansion rate (%) Example 1 7 47.3 11.2 891 2.7 Example 4 5 44.8 10.5 932 2.8 Example 5 10 46.7 10.8 1086 2.5 Comparative Example 4 2 40.1 9.5 1215 3.1 Comparative Example 5 15 41.5 10.1 2276 2.2 Comparative Example 6 / 34.6 7.4 2869 3.9

[0068] As shown in Table 2, when the amount of alkali residue increased from 2 to 15 parts by mass, the compressive and flexural strengths of the geopolymer materials in the Examples and Comparative Examples first increased and then decreased, while the electric flux first decreased and then increased. The 3-hour vertical expansion rate also showed a gradual decrease. When the amount of alkali residue in Example 1 was 7 parts by mass, the compressive and flexural strengths reached their maximum values ​​of 47.3 MPa and 11.2 MPa, respectively. The electric flux reached its minimum value of 891°C, and the 3-hour vertical expansion rate reached 2.7%.

[0069] When the amount of alkali residue used in Comparative Example 4 is too low, the alkali residue brings a low content of alkaline oxides and chloride ions to the geopolymer system, resulting in a low amount of gelling material generated by the geopolymer reaction. This results in insufficient internal structural density, reduced mechanical properties, and a high electrical flux. Simultaneously, the magnesium oxide in the magnesium residue cannot fully react with the chloride ions, resulting in a high 3h vertical expansion rate for the geopolymer. When the amount of alkali residue used in Comparative Example 5 is too high, the content of alkaline oxides and chloride ions in the geopolymer system increases. Excessive alkaline oxides crystallize and precipitate after the geopolymer reaction, causing alkali reversion and internal defects in the geopolymer. This degrades mechanical properties, shrinks the volume, and correspondingly reduces the 3h vertical expansion rate. Furthermore, the large amount of chloride ions within the geopolymer increases the geopolymer's electrical flux, leading to poor durability. When no alkali residue is added in Comparative Example 6, the geopolymer's compressive strength, flexural strength, and 3h vertical expansion rate all reach their maximum values, along with the maximum electrical flux. This indicates that the presence of alkali slag helps to generate gelling substances in the geopolymer system, improves the mechanical properties, reacts with magnesium oxide in magnesium slag, and inhibits the expansion of geopolymer materials.

[0070] (3) Inorganic reinforced whisker research experiment

[0071] Example 6

[0072] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those of Example 1, except that the inorganic reinforcing whiskers are boron nitride whiskers.

[0073] Example 7

[0074] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those of Example 1, except that the inorganic reinforcing whiskers are silicon carbide whiskers.

[0075] The geopolymer materials prepared in Examples 6 and 7 were tested for performance according to the compressive and flexural strength testing methods described in GB / T 17671-2021, "Test Methods for Strength of Cement Mortar (ISO Method)"; the chloride ion flux testing method described in GB / T 50082-2009, "Standard for Test Methods for Long-term Properties and Durability of Ordinary Concrete"; and the 3-hour vertical expansion rate testing method described in JC / T 986-2018, "Cement-based Grouting Materials." The test results are shown in Table 3.

[0076] Table 3 Effect of inorganic reinforcing whisker types on geopolymer material properties

[0077]

[0078] As can be seen from Table 3, the electric flux and 3h vertical expansion rate data of Examples 1, 6 and 7 are relatively close, indicating that the type of inorganic reinforcing whiskers has little effect on the electric flux and expansion of the geopolymer material.

[0079] The geopolymer material using short zirconium oxide whiskers in Example 1 has a compressive strength of 47.3 MPa, a flexural strength of 11.2 MPa, and a compression-flexural ratio of 4.2. The geopolymer material using boron nitride whiskers in Example 6 has a compressive strength of 48.5 MPa, a flexural strength of 9.5 MPa, and a compression-flexural ratio of 5.1. The geopolymer material using silicon carbide in Example 7 has a compressive strength of 46.6 MPa, a flexural strength of 10.8 MPa, and a compression-flexural ratio of 4.3. This is because short zirconium oxide whiskers and silicon carbide whiskers are both polycrystalline, and the whiskers are interconnected by grain boundaries, showing high strength and high toughness, which helps to improve the toughness of the geopolymer material. Boron nitride whiskers, on the other hand, have a single crystal structure, showing high hardness and high strength. When used as inorganic reinforcing whiskers in geopolymer materials, their compressive strength is too high and their flexural strength is too low.

[0080] Example 8

[0081] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the amount of zirconium oxide short whiskers is 0.5 parts.

[0082] Example 9

[0083] A geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River sediment, whose composition and preparation method are basically the same as those in Example 1, except that the amount of zirconium oxide short whiskers is 2 parts.

[0084] Comparative Example 7

[0085] A geopolymer material, whose composition and preparation method are basically the same as those of Example 1, except that no zirconium oxide short whiskers are added.

[0086] The geopolymer materials prepared in Examples 8-9 and Comparative Example 7 were tested for performance according to the compressive and flexural strength testing methods described in GB / T 17671-2021, "Test Methods for Cement Mortar Strength (ISO Method)"; the chloride ion flux testing method described in GB / T 50082-2009, "Standard for Test Methods for Long-Term Properties and Durability of Ordinary Concrete"; and the 3-hour vertical expansion rate testing method described in JC / T 986-2018, "Cement-Based Grouting Materials." The test results are shown in Table 4.

[0087] Table 4 Effect of the amount of inorganic reinforcing whiskers on the properties of geopolymer materials

[0088]

[0089] As shown in Table 4, when the amount of inorganic reinforcing whiskers increased from 0 to 2 parts by mass, the compressive strength and flexural strength of the geopolymer material in the embodiments and comparative examples showed a trend of gradual increase, the compression-to-bend ratio showed a continuous downward trend, the 3h vertical expansion rate showed a trend of gradual decrease, and the electric flux variation trend was not obvious. This is because the short zirconia whiskers can improve the tensile strength of the geopolymer material, thereby suppressing the development of microcracks inside the material, thereby improving the compressive strength and flexural strength of the material and reducing the 3h vertical expansion rate. At the same time, the higher the content of the short zirconia whiskers, the smaller the compression-to-bend ratio of the material. That is, the short zirconia whiskers can improve the mechanical properties and toughness of the geopolymer material and can also suppress expansion, but have little influence on the electric flux of the geopolymer material.

[0090] The above describes a preferred embodiment of the present invention, but it should be understood that the invention is not limited to the contents disclosed herein. As long as non-substantial improvements are made using the method concepts and technical solutions of the present invention, or the method concepts and technical solutions of the present invention are applied to other occasions, they are all within the scope of protection of the present invention.

Claims

1. A geopolymer material based on magnesium slag, alkali slag and Yellow River sediment, characterized in that: The invention is prepared from the following raw materials, in parts by mass: 40-60 parts of magnesium slag, 5-10 parts of alkali slag, 26-45 parts of Yellow River sediment, 2-5 parts of geopolymer activator, 0.5-2 parts of inorganic reinforcing whiskers, 1-2 parts of dispersant, 0.5-1 part of surfactant, and 15-20 parts of water; the magnesium slag is alkaline white mud particles, which are made by drying the alkaline white mud produced by the ammonia-soda industry and then crushing and grinding it into powder particles; the geopolymer activator is at least one of phosphoric acid and aluminum dihydrogen phosphate.

2. The geopolymer material based on magnesium slag-alkali slag-Yellow River sediment according to claim 1, characterized in that: The magnesium slag is prepared by naturally cooling the reduced slag produced by the Pidgeon process of magnesium smelting and then crushing and grinding it into powder particles.

3. The geopolymer material based on magnesium slag-alkali slag-Yellow River sediment according to any one of claims 1-2, characterized in that: The particle size of the magnesium slag is less than 300 μm, the particle size of the alkali slag is less than 300 μm, and the particle size of the Yellow River sediment is less than 600 μm.

4. The geopolymer material based on magnesium slag-alkali slag-Yellow River sediment according to claim 1, characterized in that: The inorganic reinforcing whiskers are at least one of short zirconium oxide whiskers, boron nitride whiskers, and silicon carbide whiskers.

5. The geopolymer material based on magnesium slag-alkali slag-Yellow River sediment combination according to claim 1, characterized in that: The dispersant is at least one of sodium tripolyphosphate and sodium hexametaphosphate.

6. The geopolymer material based on magnesium slag-alkali slag-Yellow River sediment according to claim 1, characterized in that: The surfactant is polycarboxylate sodium salt.

7. The method for preparing geopolymer material based on magnesium slag-alkali slag-Yellow River sediment according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Add geopolymer activator, inorganic reinforcing whiskers, dispersant and surfactant into water in sequence and mix well to obtain a mixed solution; (2) Add magnesium slag to the mixed solution and mix evenly, then add alkali slag and Yellow River silt in turn and mix evenly, cast into shape, and seal and cure at a temperature of 40 to 60°C for 12 to 48 hours to obtain a geopolymer material based on the combination of magnesium slag, alkali slag and Yellow River silt.

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