Normal-temperature stable / temperature-rising hydrated micro-powder binder and preparation method thereof

Abstract

The invention relates to a normal-temperature stable / heating hydrated micro-powder binding agent and a preparation method thereof. According to the technical scheme, the preparation method comprises the following steps: mixing an organic polymer and an organic solvent according to a mass ratio of 1: (20-40) to obtain an organic precursor modified solution; adding the micro-powder binding agent into the organic precursor modified solution according to the mass ratio of the micro-powder binding agent to the organic precursor modified solution of 1: (0.5-2), and stirring for the first time to obtain micro-powder binding agent turbid liquid; and adding a precipitator into the micro-powder binding agent suspension according to the mass ratio of the micro-powder binding agent suspension to the precipitator of 1: (2-5), stirring for the second time to obtain a modified micro-powder binding agent suspension, and carrying out solid-liquid separation, drying and grinding on the modified micro-powder binding agent suspension to prepare the normal-temperature stable / heating hydrated micro-powder binding agent. The product prepared by the invention is used for preparing a castable, and has the advantages of good fluidity, high breaking strength at normal temperature, high breaking strength at high temperature and excellent slag corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro powder binders, and specifically relates to a micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. Background Art

[0002] Binder is one of the important components of refractory castables, which is mainly divided into cement binder, chemical binder and micropowder binder. Among them, the refractory castable prepared with micropowder binder (high-activity magnesium oxide and hydrated alumina) has excellent mechanical and corrosion resistance, and is one of the main research directions for the development of high-performance refractory castables. However, micropowder binder has the problem of rapid hydration in refractory castables. Its hydration reaction at room temperature mixing stage will consume a large amount of water components in the system, resulting in a sharp decrease in the fluidity of the refractory castable (or a sharp increase in the amount of water added), which cannot meet the construction requirements. Inhibiting the hydration of micropowder binder has attracted widespread attention from researchers. For example:

[0003] 1) Patented technology of "a magnesium binder using used refractory materials as raw materials and its application" (CN113149669A) uses organic acids (citric acid, acrylic acid and oxalic acid, etc.) to inhibit the hydration of magnesium oxide. The magnesium oxide used is obtained by screening, crushing and fine grinding the used magnesium refractory materials as raw materials. This magnesium oxide has almost no activity and hydrates slowly in water. Although the thermal shock resistance and corrosion resistance of the castable prepared with it as a binder are improved, the room temperature flexural strength of the castable after heat treatment is low, which limits its application in actual production.

[0004] 2) The patented technology of “a magnesium binder and a method for preparing a refractory material using the magnesium binder” (CN112321306A) uses magnesium oleate and methylmalonic acid to inhibit the hydration of light-burned magnesium oxide, and changes the morphology of the hydration product to improve the strength of the castable. However, the light-burned magnesium oxide used is less active, and the strength of the castable is not significantly improved after the hydration is inhibited. Moreover, if this method is applied to highly active magnesium oxide with higher activity, it cannot solve the problem of poor fluidity of the castable.

[0005] 3) The author of document I (Zhang Yu. Formation of hydrated magnesium silicate in magnesium castables and its influence on material properties [D]. Wuhan University of Science and Technology, 2018) uses colloidal compound hydrated magnesium silicate generated by the reaction of silicon dioxide and magnesium oxide. Because of its slow removal of structural water, it is also widely used in magnesium castable systems. However, at room temperature, the formation rate of hydrated magnesium silicate is too slow, which affects the construction performance of the castable; moreover, the silicon dioxide in this combined system will form a liquid phase at high temperature, which will have a negative impact on the slag resistance and high-temperature mechanical properties of the castable. In addition, hydrated magnesium silicate is a magnesium-based gelling compound, which has good adaptability to magnesium or magnesium-aluminum refractory castables, but its application in other castable systems is limited.

[0006] 4) Document II (Dos Santos T, Pinola FG, Luz AP, et al.Al 2 O 3 -MgO refractory castables with enhanced explosion resistance due to in situ formation of phases with lamellar structure[J].Ceramics International,2018,44(7):8048-8056) used formic acid to inhibit the hydration of dead burned magnesium oxide, successfully inhibited the generation of cracks in dead burned magnesium oxide combined with refractory castables, and improved the dry strength of the castables. However, the active magnesium oxide combined with refractory castables used as a comparison still produced a large number of cracks. Since the activity of dead burned magnesium oxide is low, the hydration rate is relatively slow, and the generated hydration products are small, resulting in low dry strength of the castable; while the activity of active magnesium oxide is high, and the hydration rate is too fast, formic acid cannot regulate the nucleation process of magnesium hydroxide on its surface, resulting in a decrease in the fluidity of the castable and failure to meet construction requirements.

[0007] 5) The authors of document III (Luz AP, Consoni LB, Pagliosa C, et al. MgO fumes as a potential binder for in situ spinel containing refractory castables [J]. Ceramics International, 2018, 44 (13): 15453-15463) used formic acid and aluminum lactate to inhibit the hydration of magnesium oxide fume. This magnesium oxide is an extremely fine magnesium oxide powder obtained in the production process of fused magnesium oxide, and its activity is higher than that of dead burned magnesium oxide. Through the regulation of formic acid and aluminum lactate, the demoulding strength and drying strength of magnesium oxide fume combined with refractory castables are improved. However, compared with activated magnesium oxide, the activity of magnesium oxide fume is still low, and the effect of improving the strength of castables is not obvious.

[0008] In summary, the defects of the prior art are: the low activity of the micropowder binder has no obvious effect on improving the strength of the castable, and the micropowder binder with higher activity cannot inhibit hydration; the micropowder binder used for the castable has poor fluidity, low flexural strength at room temperature, low flexural strength at high temperature and poor resistance to slag erosion. Summary of the invention

[0009] The present invention aims to overcome the technical defects existing in the prior art, and aims to provide a micropowder binder which is stable at room temperature / hydrated at elevated temperatures and has a simple process, is suitable for industrial production and regulation of hydration, and has higher activity, and a preparation method thereof. The micropowder binder which is stable at room temperature / hydrated at elevated temperatures is used to prepare a castable having good fluidity, high flexural strength at room temperature, high flexural strength at high temperature, and excellent resistance to slag erosion.

[0010] To achieve the above object, the technical solution adopted by the present invention is:

[0011] The organic polymer and the organic solvent are mixed at a mass ratio of 1:20 to 40 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:0.5 to 2 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:2 to 5 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0012] The organic polymer is one of polyacrylamide-acrylonitrile, poly-N-acryloylglycineamide, poloxamer, polyvinyl alcohol and polyethylene; the organic polymer is industrial pure or analytical pure.

[0013] The organic solvent is one of dimethyl sulfoxide, acetone, ether and toluene; the organic solvent is industrial pure or analytical pure.

[0014] The micro powder binder is active magnesium oxide or hydrated aluminum oxide; the micro powder binder is industrial pure or analytical pure; the particle size of the micro powder binder is ≤0.044 mm.

[0015] The first stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 2 to 5 hours.

[0016] The precipitant is methanol or ethanol; the precipitant is industrial pure or analytical pure.

[0017] The second stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 0.1 to 0.2 hours.

[0018] The solid-liquid separation is carried out by centrifugal separation at 8000-12000 rpm for 5-20 minutes.

[0019] The drying conditions are: drying temperature is 80-110° C.; and drying time is 12-48 hours.

[0020] Due to the adoption of the above technical solution, the beneficial effects of the present invention compared with the prior art are:

[0021] 1. The micropowder binder that is stable at room temperature / hydrated at elevated temperatures provided by the present invention has a modified layer with a temperature-sensitive effect on the surface during the room-temperature mixing and pouring stage of the refractory castable. The modified layer is insoluble in water at room temperature and separates water from the micropowder binder. Therefore, the micropowder binder does not hydrate at this stage and can remain stable during the mixing and pouring stage of the refractory castable, thereby improving the fluidity of the castable and meeting the construction requirements. Subsequently, during the curing stage (the temperature is generally 50-80°C), the modified layer dissolves in water, at which time the micropowder binder reacts with water, fully hydrates to form a binding phase, and improves the room-temperature flexural strength of the refractory castable.

[0022] 2. The room temperature stable / heated hydrated micropowder binder provided by the present invention is uniformly hydrated in the refractory castable, and the grains of the hydrated binding phase are fine. It is easier to react with other components in the high temperature treatment stage to form high temperature binding phases such as magnesium aluminum spinel, which can significantly improve the high temperature flexural strength and slag erosion resistance of the refractory castable.

[0023] 3. The present invention mixes an organic polymer and an organic solvent to prepare an organic precursor modified solution, then adds a micropowder binder to the organic precursor modified solution, fully stirs, adds a precipitant and performs centrifugal treatment, and then dries and grinds to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures; the preparation process is simple and suitable for industrial production.

[0024] Therefore, the present invention has the characteristics of simple process, suitability for industrial production and regulation of hydration and higher activity. The prepared micropowder binder that is stable at room temperature / hydrated at elevated temperature is used to prepare castables with good fluidity, high flexural strength at room temperature, high flexural strength at high temperature and excellent resistance to slag erosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a table showing the pH change over time at 25°C and 60°C for a micropowder binder that is stable at room temperature / hydrated at elevated temperatures. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific implementation modes, but is not intended to limit the protection scope thereof.

[0027] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0028] The organic polymer and the organic solvent are mixed at a mass ratio of 1:20 to 40 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:0.5 to 2 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:2 to 5 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0029] The organic polymer is one of polyacrylamide-acrylonitrile, poly-N-acryloylglycineamide, poloxamer, polyvinyl alcohol and polyethylene; the organic polymer is industrial pure or analytical pure.

[0030] The organic solvent is one of dimethyl sulfoxide, acetone, ether and toluene; the organic solvent is industrial pure or analytical pure.

[0031] The micro powder binder is active magnesium oxide or hydrated aluminum oxide; the micro powder binder is industrial pure or analytical pure.

[0032] The first stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 2 to 5 hours.

[0033] The precipitant is methanol or ethanol; the precipitant is industrial pure or analytical pure.

[0034] The second stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 0.1 to 0.2 hours.

[0035] The solid-liquid separation is carried out by centrifugal separation at 8000-12000 rpm for 5-20 minutes.

[0036] The drying conditions are: drying temperature is 80-110° C.; and drying time is 12-48 hours.

[0037] In this specific implementation mode:

[0038] The particle size of the micro powder binder is ≤0.044 mm.

[0039] In this specific implementation, the pH value is measured by adding 2g of the micro-powder binder stable at room temperature / hydrated at elevated temperature into 100ml of water and using a pH meter to measure its change within 600 seconds; when the micro-powder binder stable at room temperature / hydrated at elevated temperature reacts with water to generate a hydration product, the OH in the water - will increase, which will lead to an increase in pH.

[0040] In this specific implementation: the refractory castable is prepared according to the national standards GB / T 4513.5 and GB / T 4513.6, and its components include plate-shaped corundum aggregate (69wt%), plate-shaped corundum fine powder (20wt%), α-alumina powder (6wt%) and powder binder (5wt%), and the amount of water added is 5wt%. The flow value of the refractory castable is tested according to GB / T 4513.4-2017. The demoulding strength of the refractory castable is tested according to GB / T 3001-2017.

[0041] This will not be described in detail in the embodiments.

[0042] Example 1

[0043] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0044] The organic polymer and the organic solvent are mixed at a mass ratio of 1:20 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:0.5 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:2 to obtain a precipitant to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0045] The organic polymer is polyacrylamide co-acrylonitrile; the organic polymer is industrial pure.

[0046] The organic solvent is dimethyl sulfoxide; the organic solvent is industrial pure.

[0047] The micro powder binder is active magnesium oxide; the micro powder binder is industrial pure or analytical pure.

[0048] The first stirring was carried out at a rotation speed of 400 rpm and a temperature of 20° C. for 2 hours.

[0049] The precipitant is methanol; the precipitant is industrial pure.

[0050] The second stirring was carried out at a rotation speed of 400 rpm and a temperature of 20° C. for 0.1 hour.

[0051] The solid-liquid separation was carried out by centrifugation at 8000 rpm for 5 minutes.

[0052] The drying conditions are: drying temperature is 110° C.; and drying time is 12 hours.

[0053] The micro powder binder prepared in this example is stable at room temperature / hydrated at elevated temperature. Figure 1 As shown, Figure 1 The following is a table showing the pH change over time of the room temperature stable / heated hydrated micropowder binder prepared in Example 1 at 25°C and 60°C. Figure 1 It can be seen that the pH value at 25°C increases from 6.3 to 7.0, while the pH value at 60°C increases from 6.4 to 10.0.

[0054] The properties of the refractory castable prepared by the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 105%; the demoulding flexural strength after curing at 60°C is 4.45MPa

[0055] Example 2

[0056] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0057] The organic polymer and the organic solvent are mixed at a mass ratio of 1:25 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:1 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:4 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0058] The organic polymer is poly-N-acryloylglycinamide; the organic polymer is analytically pure.

[0059] The organic solvent is acetone; the organic solvent is analytically pure.

[0060] The micro powder binder is active magnesium oxide; the micro powder binder is analytically pure.

[0061] The first stirring was carried out at a rotation speed of 500 rpm and a temperature of 25° C. for 4 hours.

[0062] The precipitant is methanol; the precipitant is analytically pure.

[0063] The second stirring was carried out at a rotation speed of 500 rpm and a temperature of 25° C. for 0.2 hours.

[0064] The solid-liquid separation was carried out by centrifugation at 12000 rpm for 10 minutes.

[0065] The drying conditions are: drying temperature is 100° C.; and drying time is 24 hours.

[0066] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.1 to 7.2 at 25°C, and increased from 6.3 to 10.1 at 60°C.

[0067] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 107%; the demoulding flexural strength after curing at 60°C is 4.37 MPa.

[0068] Example 3

[0069] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0070] The organic polymer and the organic solvent are mixed at a mass ratio of 1:30 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:1.5 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:3 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0071] The organic polymer is poloxamer; the organic polymer is industrial pure.

[0072] The organic solvent is ether; the organic solvent is industrial pure.

[0073] The micro powder binder is active magnesium oxide, and the micro powder binder is industrial pure.

[0074] The first stirring was carried out at a rotation speed of 600 rpm and a temperature of 30° C. for 3.5 hours.

[0075] The precipitant is ethanol; the precipitant is industrial pure.

[0076] The second stirring was carried out at a rotation speed of 600 rpm and a temperature of 30° C. for 0.1 hour.

[0077] The solid-liquid separation was carried out by centrifugation at 10,000 rpm for 15 minutes.

[0078] The drying conditions are: drying temperature is 80° C.; and drying time is 48 hours.

[0079] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.2 to 7.1 at 25°C, and increased from 6.3 to 10.2 at 60°C.

[0080] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 102%; the demoulding flexural strength after curing at 60°C is 4.32 MPa.

[0081] Example 4

[0082] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0083] The organic polymer and the organic solvent are mixed at a mass ratio of 1:35 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:2 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:5 to obtain a precipitant to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0084] The organic polymer is polyvinyl alcohol; the organic polymer is analytically pure.

[0085] The organic solvent is toluene; the organic solvent is analytically pure.

[0086] The micro powder binder is active magnesium oxide; the micro powder binder is analytically pure.

[0087] The first stirring was carried out at a rotation speed of 700 rpm and a temperature of 25° C. for 5 hours.

[0088] The precipitant is ethanol; the precipitant is analytically pure.

[0089] The second stirring was carried out at a rotation speed of 700 rpm and a temperature of 25° C. for 0.15 hours.

[0090] The solid-liquid separation was carried out by centrifugation at 9000 rpm for 20 minutes.

[0091] The drying conditions are: drying temperature is 90° C.; and drying time is 36 hours.

[0092] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.4 to 7.0 at 25°C, and increased from 6.1 to 10.1 at 60°C.

[0093] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 100%; the demoulding flexural strength after curing at 60°C is 4.35 MPa.

[0094] Example 5

[0095] A micro powder binder that is stable at room temperature / hydrated at elevated temperatures and a preparation method thereof. The preparation method described in this specific embodiment is:

[0096] The organic polymer and the organic solvent are mixed at a mass ratio of 1:40 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:0.5 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:3.5 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

[0097] The organic polymer is polyethylene; the organic polymer is industrial pure.

[0098] The organic solvent is dimethyl sulfoxide; the organic solvent is industrial pure.

[0099] The micro powder binder is active magnesium oxide; the micro powder binder is industrial pure.

[0100] The first stirring was carried out at a rotation speed of 800 rpm and a temperature of 30° C. for 3 hours.

[0101] The precipitant is ethanol; the precipitant is industrial pure.

[0102] The second stirring was carried out at a rotation speed of 800 rpm and a temperature of 30° C. for 0.2 hours.

[0103] The solid-liquid separation was carried out by centrifugation at 11000 rpm for 20 minutes.

[0104] The drying conditions are: drying temperature is 110° C.; and drying time is 12 hours.

[0105] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.0 to 7.1 at 25°C, and increased from 6.3 to 10.3 at 60°C.

[0106] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 101%; the demoulding flexural strength after curing at 60°C is 4.29 MPa.

[0107] Example 6

[0108] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. Except for the micro powder binder, the rest of this embodiment is the same as that of embodiment 1:

[0109] The micro powder binder is hydrated aluminum oxide.

[0110] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.3 to 7.0 at 25°C, and increased from 6.2 to 10.0 at 60°C.

[0111] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 110%; the demoulding flexural strength after curing at 60°C is 3.71 MPa.

[0112] Example 7

[0113] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. Except for the micro powder binder, the rest of this embodiment is the same as that of embodiment 2:

[0114] The micro powder binder is hydrated aluminum oxide.

[0115] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.2 to 7.2 at 25°C, and increased from 6.2 to 10.1 at 60°C.

[0116] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 112%; the demoulding flexural strength after curing at 60°C is 3.75 MPa.

[0117] Example 8

[0118] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. Except for the micro powder binder, the rest of this embodiment is the same as that of embodiment 3:

[0119] The micro powder binder is hydrated aluminum oxide.

[0120] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.3 to 7.1 at 25°C, and increased from 6.3 to 10.1 at 60°C.

[0121] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 115%; the demoulding flexural strength after curing at 60°C is 3.79 MPa.

[0122] Example 9

[0123] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. Except for the micro powder binder, the rest of this embodiment is the same as that of embodiment 4:

[0124] The micro powder binder is hydrated aluminum oxide.

[0125] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.1 to 7.0 at 25°C, and increased from 6.0 to 10.1 at 60°C.

[0126] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 113%; the demoulding flexural strength after curing at 60°C is 3.82 MPa.

[0127] Example 10

[0128] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. Except for the micro powder binder, the rest of this embodiment is the same as that of embodiment 5:

[0129] The micro powder binder is hydrated aluminum oxide.

[0130] The pH value of the room temperature stable / temperature hydrated micropowder binder prepared in this example increased from 6.2 to 7.4 at 25°C, and increased from 6.1 to 10.3 at 60°C.

[0131] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this example are as follows: the flow value is 114%; the demoulding flexural strength after curing at 60°C is 3.78 MPa.

[0132] Comparative Example 1

[0133] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. This comparative example is the same as Example 1 except that no organic polymer is added.

[0134] The pH value of the room temperature stable / heated hydrated micropowder binder prepared in this comparative example increased from 6.2 to 10.6 at 25°C, and increased from 6.1 to 10.8 at 60°C.

[0135] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this comparative example include: a flow value of 35%; and a demoulding flexural strength of 2.13 MPa after curing at 60°C.

[0136] Comparative Example 2

[0137] A micro powder binder that is stable at room temperature / hydrated at elevated temperature and a preparation method thereof. This comparative example is the same as Example 6 except that no organic polymer is added:

[0138] The pH value of the room temperature stable / heated hydrated micropowder binder prepared in this comparative example increased from 6.3 to 10.5 at 25°C, and increased from 6.4 to 10.4 at 60°C.

[0139] The properties of the refractory castable prepared by using the room temperature stable / heated hydrated micropowder binder prepared in this comparative example include: a flow value of 70%; and a demoulding flexural strength of 1.81 MPa after curing at 60°C.

[0140] The beneficial effects of the present invention compared with the prior art are:

[0141] 1. The micropowder binder that is stable at room temperature / hydrated at elevated temperatures provided by the present invention has a modified layer with a temperature-sensitive effect on the surface during the room-temperature mixing and pouring stage of the refractory castable. The modified layer is insoluble in water at room temperature and separates water from the micropowder binder. Therefore, the micropowder binder does not hydrate at this stage and can remain stable during the mixing and pouring stage of the refractory castable, thereby improving the fluidity of the castable and meeting the construction requirements. Subsequently, during the curing stage (the temperature is generally 50-80°C), the modified layer dissolves in water, at which time the micropowder binder reacts with water, fully hydrates to form a binding phase, and improves the room-temperature flexural strength of the refractory castable.

[0142] 2. The room temperature stable / heated hydrated micropowder binder provided by the present invention is uniformly hydrated in the refractory castable, and the grains of the hydrated binding phase are fine. It is easier to react with other components in the high temperature treatment stage to form high temperature binding phases such as magnesium aluminum spinel, which can significantly improve the high temperature flexural strength and slag erosion resistance of the refractory castable.

[0143] 3. The present invention mixes an organic polymer and an organic solvent to prepare an organic precursor modified solution, then adds a micropowder binder to the organic precursor modified solution, fully stirs, adds a precipitant and performs centrifugal treatment, and then dries and grinds to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures; the preparation process is simple and suitable for industrial production.

[0144] The room temperature stable / temperature hydrated micropowder binder prepared in this specific embodiment was tested: the pH value at 25°C increased from 6.0-6.4 to 7.0-7.4, and the pH value at 60°C increased from 6.0-6.4 to 10.0-10.3; while the pH values ​​of the room temperature stable / temperature hydrated micropowder binders prepared in Comparative Examples 1 and 2 at 25°C increased from 6.2 and 6.3 to 10.5 and 10.6 respectively, and the pH values ​​at 60°C increased from 6.1 and 6.4 to 10.4 and 10.8 respectively.

[0145] The performance of the refractory castable prepared by the micropowder binder that is stable at room temperature / hydrated at elevated temperature prepared in this example was tested as follows: the flow value was 100-115%; the demolding flexural strength after curing at 60°C was 3.71-4.45MPa; while the performance of the refractory castable prepared by the micropowder binder that is stable at room temperature / hydrated at elevated temperature prepared in Comparative Examples 1 and 2 was as follows: the flow values ​​were 35% and 70% correspondingly; the demolding flexural strength after curing at 60°C was 1.81MPa and 2.13MPa correspondingly.

[0146] Therefore, the present invention has the characteristics of simple process, suitability for industrial production and regulation of hydration and higher activity. The prepared micropowder binder that is stable at room temperature / hydrated at elevated temperature is used to prepare castables with good fluidity, high flexural strength at room temperature, high flexural strength at high temperature and excellent resistance to slag erosion.

Claims

1. A method for preparing a micropowder binder that is stable at room temperature / hydrated at elevated temperatures, characterized in that: The organic polymer and the organic solvent are mixed at a mass ratio of 1:20 to 40 to obtain an organic precursor modified solution; the micropowder binder is then added to the organic precursor modified solution at a mass ratio of 1:0.5 to 2 to obtain a micropowder binder suspension; the precipitant is then added to the micropowder binder suspension at a mass ratio of 1:2 to 5 to obtain a precipitant, and the mixture is stirred for a second time to obtain a modified micropowder binder suspension; the modified micropowder binder suspension is subjected to solid-liquid separation, dried, and ground to obtain a micropowder binder that is stable at room temperature / hydrated at elevated temperatures.

2. The method for preparing the normal temperature / heated hydrated micropowder binder according to claim 1, characterized in that: The organic polymer is one of polyacrylamide-acrylonitrile, poly-N-acryloylglycineamide, poloxamer, polyvinyl alcohol and polyethylene; the organic polymer is industrial pure or analytical pure.

3. The method for preparing the micropowder binder stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The organic solvent is one of dimethyl sulfoxide, acetone, ether and toluene; the organic solvent is industrial pure or analytical pure.

4. The method for preparing the micropowder binder stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The micro powder binder is active magnesium oxide or hydrated aluminum oxide; the micro powder binder is industrial pure or analytical pure; the particle size of the micro powder binder is ≤0.044 mm.

5. The method for preparing the micropowder binder stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The first stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 2 to 5 hours.

6. The method for preparing the micropowder binder that is stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The precipitant is methanol or ethanol; the precipitant is industrial pure or analytical pure.

7. The method for preparing the micropowder binder stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The second stirring is carried out at a rotation speed of 400 to 800 rpm and a temperature of 20 to 30° C. for 0.1 to 0.2 hours.

8. The method for preparing the micropowder binder that is stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The solid-liquid separation is carried out by centrifugal separation at 8000-12000 rpm for 5-20 minutes.

9. The method for preparing the micropowder binder stable at room temperature / hydrated at elevated temperature according to claim 1, characterized in that: The drying conditions are: drying temperature is 80-110° C.; and drying time is 12-48 hours.

10. A micro powder binder that is stable at room temperature / hydrated at elevated temperatures, characterized in that The room temperature stable / temperature hydrated fine powder binder is a room temperature stable / temperature hydrated fine powder binder prepared by the preparation method of the room temperature stable / temperature hydrated fine powder binder according to any one of claims 1 to 9.

Images