Preparation method of coal gangue active activator and active coal gangue powder based thereon

Abstract

The application discloses a coal gangue activity activator and a preparation method of active coal gangue powder based on the coal gangue activity activator. The coal gangue activity activator is obtained by mixing and grinding CaCO3, a C / Al compound, zeolite powder, an iron-based auxiliary agent, a calcium-based auxiliary agent, a rare earth auxiliary agent, KMnO4, isobutyl alcohol, a fatty acid glyceride and fluorite; then, the coal gangue is crushed and ground, mixed with the coal gangue activity activator, stirred and combusted, the mixed coal gangue after combustion is ground to obtain the active coal gangue powder. The coal gangue is modified by the activity activator, in the spontaneous combustion process of the coal gangue, the coal gangue can utilize the combustion heat to change the structure and react with the coal gangue, the activity of the coal gangue is greatly improved, the mixing amount of the coal gangue in the cement is improved, and the resource utilization of the natural coal gangue is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to an activator, in particular to a coal gangue activity activator and a preparation method of active coal gangue powder based thereon. BACKGROUND

[0002] Coal gangue is a solid waste produced in the process of coal production in coal mines. At present, coal gangue has been used for filling pits, cement admixture, concrete aggregate, and making less clinker cement, hollow bricks, concrete blocks, and ceramic tiles. However, due to the low activity and limited strength of coal gangue, it cannot be used in large quantities. Existing research shows that using cement mixed with coal gangue or directly adding coal gangue powder to concrete can improve the density of concrete and improve its frost resistance, impermeability, and sulfate erosion resistance. That is, the addition of coal gangue can improve the durability of concrete. However, it is found in research and use that coal gangue with high carbon content affects the performance of concrete if it is not self-ignited. The activity of self-ignited coal gangue is low, and the pozzolanic activity has not been well activated. Therefore, how to more effectively activate and improve the potential activity of coal gangue is a major problem for researchers. At present, the activation of coal gangue activity is mainly through physical activation, thermal activation, microwave irradiation activation, and chemical activation to improve the activity of coal gangue.

[0003] Physical activation is to grind coal gangue to superfine powder to make its particles very small and improve its activity. However, the increase in fineness means an increase in energy consumption, which limits the degree of grinding of coal gangue, so that most of the coal gangue is not involved in the reaction or plays a physical filling role, and its activity has not been well developed.

[0004] Thermal activation aims to use high temperature to make the calcined coal gangue contain a large amount of active silicon oxide and aluminum oxide. However, due to the complex composition of coal gangue, the best temperature for calcining coal gangue cannot be universally determined. Moreover, the activity of calcined coal gangue needs to be developed under certain conditions, i.e., pure coal gangue does not produce cementing strength in water and needs to produce secondary hydration reaction after adding cement under alkaline or sulfate conditions. In order to promote the further development of coal gangue activity, chemical activation can be combined.

[0005] Chemical activation mainly destroys the network structure of Si-O through alkali activation. However, the Si-O structure is relatively stable, and the influence of the type and amount of activator and the PH value of the existing solution is related. The pure chemical activation process is relatively slow, and in order to promote the activation effect, thermal activation is generally combined.

[0006] Therefore, to improve the activity of coal gangue, current research tends to employ one or more activation methods simultaneously, such as physical-thermal or thermo-chemical combined activation. However, combined activation requires consideration of numerous factors, resulting in limited research in this area. Currently, coal gangue activation primarily involves grinding self-combusting or non-self-combusting coal gangue after combustion to form activated coal gangue with a certain level of activity, which can then be used as a cementitious admixture. Summary of the Invention

[0007] To address the aforementioned problems, this invention aims to provide an activator for non-self-igniting coal gangue, based on existing methods for activating coal gangue, to enhance the activity of coal gangue during combustion.

[0008] To achieve the above objectives, the present invention proposes the following technical solution:

[0009] A coal gangue activator is obtained by grinding the following components after uniform mixing, with the following mass parts as follows:

[0010]

[0011] Furthermore, the grinding time after the components of the coal gangue activator described in this invention are mixed evenly is 10-20 minutes.

[0012] Furthermore, the CaCO3 particle size described in this invention is 200 mesh to 400 mesh.

[0013] Furthermore, the C / Al composite of the present invention is a carbon microsphere-amorphous aluminum hydroxide composite prepared under hydrothermal conditions using carbon microspheres as templates and aluminum salts as aluminum sources. It can be considered as a precursor of nano-alumina hollow microspheres; wherein the C in the carbon microspheres and the Al in the aluminum salts... 3+ The molar ratio is 1:1 to 1:3.

[0014] Furthermore, the zeolite powder of the present invention has a particle size of 150 mesh to 400 mesh.

[0015] Furthermore, the calcium-based additive of the present invention is one or a mixture of two of CaCl2 or CaSO4 in any proportion.

[0016] Furthermore, the iron-based additive of the present invention is one or a mixture of two of Fe2O3 or FeCl3 in any proportion.

[0017] Furthermore, the rare earth additives of the present invention are lanthanides or a mixture of cerium and lanthanides, wherein the mass percentage of cerium does not exceed 50%.

[0018] The application further provides a preparation method of the active coal gangue powder based on the coal gangue activity activator, comprising the following steps:

[0019] (1) crushing and grinding the coal gangue to a specific surface area of not less than 100m 2 / kg, then mixing and stirring the coal gangue with the coal gangue activity activator, and burning the mixture;

[0020] (2) grinding the mixed coal gangue after burning in step (1) to obtain the active coal gangue powder;

[0021] The coal gangue activity activator accounts for 5-12% of the mass of the coal gangue in step (1).

[0022] Further, the coal gangue in step (1) is the coal gangue block not self-ignited in the coal production process.

[0023] Further, the burning temperature of the coal gangue in step (1) is 400-900℃, and the burning time is not less than 3h.

[0024] Further, the specific surface area of the coal gangue after burning and grinding in step (2) is not less than 400m 2 / kg.

[0025] The application has the following beneficial effects:

[0026] (1) The coal gangue active activator prepared by the present application has the following components: CaCO3 and a main component for adjusting the silicon-calcium ratio of the coal gangue; a calcium-based additive can absorb sulfur compounds generated under the action of high-temperature combustion and decomposition of the coal gangue, has a certain desulfurization effect, and promotes the synthesis of active substances of the coal gangue; fluorite can reduce the activation temperature of the coal gangue and promote the synthesis of active substances of the coal gangue; an iron-based additive can promote the combustion of the coal gangue before the combustion of the coal gangue and participate in the generation process of the active substances of the coal gangue during the high-temperature combustion of the coal gangue, thereby generating iron aluminate tetra-calcium active substances and improving the pozzolanic activity of the active substances of the coal gangue; KMnO4 can decompose oxygen at high temperature, increase the oxygen content of the system, effectively reduce the combustible temperature of the coal gangue under the promotion of the rare earth additive, promote the combustion of the coal gangue, speed up the combustion speed, and be beneficial to the rapid generation of light active silicon dioxide particles; isobutyl alcohol can not only reduce the ignition point of the coal gangue but also absorb sulfur compounds formed during the combustion of the coal gangue; fatty acid glycerides can effectively reduce the combustion activation energy of the coal gangue and speed up the combustion of the coal gangue; zeolite powder can not only absorb a large amount of light active silicon dioxide and other substances generated during the combustion of the coal gangue, but also can change the structure and crystal form at the temperature of the combustion of the coal gangue in the present application, thereby improving the activity of the zeolite powder and promoting the improvement of the overall activity of the coal gangue; in particular, the incorporation of the C / Al composite can significantly improve the grindability of the non-spontaneous coal gangue, increase the aluminum-calcium ratio and structural porosity of the modified coal gangue formed in the reaction with the coal gangue, and be beneficial to the grinding and the improvement of the activity.

[0027] (2) The various components in the activator of the present application can promote and speed up the combustion of the coal gangue, and can assist in absorbing sulfur compounds and other substances that may pollute the air generated during the combustion of the coal gangue; can realize the adsorption and preservation of the active substances of the coal gangue, avoid the inconvenience of collecting the light active substances floating in the air, and carry out active reactions with the substances generated by the combustion of the coal gangue to improve the pozzolanic activity of the combustion products of the coal gangue. Through the synergistic effect of the components, the coal gangue activation temperature is effectively reduced, the activity is promoted, and the quality of the active substances is improved.

[0028] (3) The present application can modify the non-spontaneous coal gangue with low activity and low utilization rate through the active activator, utilize the heat generated by the combustion of the coal gangue to change the structure of the coal gangue during the spontaneous combustion of the coal gangue, and react with the coal gangue, thereby greatly improving the activity of the coal gangue, increasing the amount of the coal gangue in the cement, and realizing the resource utilization of the non-natural coal gangue. DETAILED DESCRIPTION

[0029] In order to better understand the present application, the following embodiments are further described, but it should not be understood that the present application is only applicable to the following examples. Some non-essential modifications and adjustments made by those skilled in the art based on the content of the above application still belong to the protection scope of the present application.

[0030] Embodiment 1

[0031] A preparation method of activated coal gangue powder comprises the following steps:

[0032] (1) crushing and grinding the coal gangue to prepare a powder with a specific surface area of 140 m 2 / kg, mixing and stirring the coal gangue with a coal gangue activity activator, and burning the mixture;

[0033] The coal gangue is burned at a temperature of 400℃ for 6h;

[0034] (2) grinding the burned coal gangue mixture to obtain activated coal gangue powder;

[0035] The burned coal gangue is ground, and the specific surface area of the ground coal gangue is 535 m 2 / kg, and the total grinding time is recorded as 25min.

[0036] The coal gangue activity activator accounts for 5% of the mass of the coal gangue, and is composed of the following components in mass fraction:

[0037]

[0038] The CaCO3 has a particle size of 200 mesh, the zeolite powder has a particle size of 400 mesh, the calcium-based additive is CaCl2, the iron-based additive is FeCl3, and the rare earth additive is lanthanum nitrate.

[0039] The C / Al composite is prepared by weighing 1 mole of carbon microspheres (140g) as a template and 1 mole of aluminum sulfate (1710g), dissolving the aluminum sulfate in 4000g of water, adding a block copolymer, pouring the carbon microspheres into the aluminum sulfate solution, uniformly dispersing by ultrasonic, heating and boiling, slowly stirring until completely evaporated to form a mixture, washing the mixture with deionized water and anhydrous ethanol, and drying to obtain.

[0040] Embodiment 2

[0041] A preparation method of activated coal gangue powder comprises the following steps:

[0042] (1) crushing and grinding the coal gangue to prepare a powder with a specific surface area of 140 m 2 / kg, mixing and stirring the coal gangue with a coal gangue activity activator, and burning the mixture;

[0043] The coal gangue is burned at a temperature of 400℃ for 6h;

[0044] (2) grinding the burned coal gangue mixture to obtain activated coal gangue powder;

[0045] The burned coal gangue is ground, and the specific surface area of the ground coal gangue is 535 m2 / kg.

[0046] The coal gangue activity activator accounts for 8% of the mass of the coal gangue, and is composed of the following components in mass fraction:

[0047]

[0048] The CaCO3 particle size is 400 mesh, the zeolite powder particle size is 150 mesh, the calcium-based auxiliary agent is CaSO4, the iron-based auxiliary agent is Fe2O3, and the rare earth auxiliary agent is lanthanum sulfate and cerium sulfate with a mass ratio of 2:1.

[0049] The C / Al composite preparation method is as follows: 1 mole of mass parts of carbon microspheres (140 g) is weighed as a template and 1 mole of mass parts of aluminum sulfate (2400 g), the aluminum sulfate is dissolved in 5000 g of water, then a block copolymer is added, the carbon microspheres are poured into the aluminum sulfate solution, ultrasonic dispersion is performed until uniform, then heating and boiling are performed, slow stirring is performed until complete evaporation, then a mixture is formed, the mixture is washed with deionized water and anhydrous ethanol, and drying is performed to obtain the C / Al composite.

[0050] Example 3

[0051] A preparation method of activated coal gangue powder includes the following steps:

[0052] (1) The coal gangue is crushed, mixed with an activity activator, stirred, and burned;

[0053] The coal gangue is burned at a temperature of 600°C for 4 hours;

[0054] (2) The burned coal gangue is ground to obtain activated coal gangue powder;

[0055] The burned coal gangue is ground for 25 minutes, and the specific surface area is 537 m 2 / kg.

[0056] The coal gangue activity activator accounts for 12% of the total mass, and is composed of the following components in mass fraction:

[0057]

[0058]

[0059] The CaCO3 particle size is 300 mesh, the zeolite powder particle size is 200 mesh, the calcium-based auxiliary agent is CaCl2 and CaSO4 with a mass ratio of 1:1, the iron-based auxiliary agent is Fe2O3 and FeCl3 with a mass ratio of 1:1, and the rare earth auxiliary agent is lanthanum nitrate and cerium sulfate with a mass ratio of 1:1.

[0060] The preparation method of the C / Al composite is as follows: 1 mol of carbon microspheres (140 g) is weighed as a template and 1 mol of aluminum sulfate (5100 g) is weighed, the aluminum sulfate is dissolved in 10000 g of water, then a block copolymer is added, the carbon microspheres are poured into the aluminum sulfate solution, ultrasonic dispersion is performed until uniform, heating and boiling are performed, slow stirring is performed until complete evaporation, a mixture is formed, the mixture is washed with deionized water and anhydrous ethanol, and drying is performed to obtain the mixture.

[0061] Example 4

[0062] A preparation method of activated coal gangue powder comprises the following steps:

[0063] (1) After the coal gangue is crushed, the coal gangue is mixed and stirred with an active activator, and is combusted;

[0064] The combustion temperature of the coal gangue is 700℃, and the combustion time is 4h;

[0065] (2) The combusted coal gangue is ground to obtain the activated coal gangue powder;

[0066] The coal gangue is combusted and ground for 25 min after combustion, and the specific surface area is 534m 2 / kg.

[0067] The active activator of the coal gangue accounts for 10% of the total mass, and is composed of the following components in mass fractions:

[0068]

[0069]

[0070] The CaCO3 has a particle size of 250 mesh, the zeolite powder has a particle size of 250 mesh, the calcium-based additive is CaSO4, the iron-based additive is Fe2O3, and the rare earth additive is lanthanum nitrate.

[0071] The preparation method of the C / Al composite is as follows: 1 mol of carbon microspheres (140 g) is weighed as a template and 1 mol of aluminum sulfate (5100 g) is weighed, the aluminum sulfate is dissolved in 10000 g of water, then a block copolymer is added, the carbon microspheres are poured into the aluminum sulfate solution, ultrasonic dispersion is performed until uniform, heating and boiling are performed, slow stirring is performed until complete evaporation, a mixture is formed, the mixture is washed with deionized water and anhydrous ethanol, and drying is performed to obtain the mixture.

[0072] Comparative Example 1

[0073] The coal gangue is coal gangue generated in a coal production process and has not undergone spontaneous combustion, and is ground to a specific surface area of 523m 2 / kg. The grinding time is recorded as 45 min.

[0074] Comparative Example 2

[0075] A preparation method of activated coal gangue powder, comprising the following steps:

[0076] (1) crushing and grinding the coal gangue, and then burning the coal gangue;

[0077] The coal gangue is burned at a temperature of 400 DEG C for 3 hours.

[0078] (2) grinding the burned coal gangue to obtain the activated coal gangue powder;

[0079] The burned coal gangue is ground to a specific surface area of 520 m 2 / kg for 40 minutes.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that the C / Al composite is not added in the coal gangue activity activator; when the prepared coal gangue mixture is ground, the specific surface area is 452 m 2 / kg after 25 minutes of grinding; and the specific surface area is 512 m 2 / kg after 35 minutes of further grinding.

[0082] Comparative Example 4

[0083] The difference from Example 1 is that the same mass of nano-aluminum oxide is added in the coal gangue activity activator instead of the C / Al composite; the specific surface area is 484 m 2 / kg after 25 minutes of grinding, and the specific surface area is 518 m 2 / kg after 35 minutes of grinding.

[0084] The nano-aluminum oxide is obtained by calcining the C / Al composite prepared in Example 1 at 800 DEG C.

[0085] Comparative Example 5

[0086] The difference from Example 1 is that the fluorite powder is not added in the coal gangue activity activator; the specific surface area is 504 m 2 / kg after 25 minutes of grinding.

[0087] Comparative Example 6

[0088] The difference from Example 1 is that the CaCO3 and calcium-based auxiliary agent are not added in the coal gangue activator; the specific surface area is 510 m 2 / kg after 25 minutes of grinding.

[0089] Comparative Example 7

[0090] The difference from Example 1 is that no rare earth additive is used in the coal gangue activator, and the specific surface area is 518 m2 / kg after 25 min of grinding. 2

[0091] Comparative Example 8

[0092] The difference from Example 1 is that no KMnO4 is used in the coal gangue activator, and the specific surface area is 495 m2 / kg after 25 min of grinding. 2

[0093] Comparative Example 9

[0094] The difference from Example 1 is that no iron-based additive is used in the coal gangue activator, and the specific surface area is 502 m2 / kg after 25 min of grinding. 2

[0095] Comparative Example 10

[0096] The difference from Example 1 is that no zeolite powder is used in the coal gangue activator, and the specific surface area is 501 m2 / kg after 25 min of grinding. 2

[0097] In each of the above examples, the activity of the coal gangue is compared according to the method of the 28d compressive strength ratio test of cement mortar in GB / T12957-2005, the mixing amount is mixed uniformly according to the provisions of GB / T12957-2005, and the low cementitious material is mixed with gypsum dihydrate at a mass ratio of 90:10, and the total mixing amount is 30% of the mass of the cement.

[0098] The experiment uses P.O.42.5 ordinary Portland cement factory, and the 28d compressive strength and activity index of each group of samples are tested according to the relevant provisions of GB / T12957-2005, as shown in Table 1:

[0099] Table 1: 28d compressive strength and activity index of each group of samples

[0100]

[0101]

[0102] ​​​​As can be seen from Table 1, the coal gangue of Comparative Example 1 has low activity without calcination, and the activity of the coal gangue of Comparative Example 2 and Example 1 increases slightly after calcination at 400℃ without adding activator, while the activity of the coal gangue of Example 1 is greatly improved after adding activator, which shows that the activator can not only improve the activity of the coal gangue, but also greatly reduce the temperature for activating the activity of the coal gangue. As can be seen from Comparative Example 3 and Example 1, the incorporation of C / Al composite can significantly improve the activity of the coal gangue, and the specific surface area of Comparative Example 3 is significantly lower than that of Example 1 under the same grinding conditions. If the same specific surface area as Example 1 is achieved, the grinding time is significantly prolonged, which shows that the grindability of Comparative Example 3 without C / Al composite is significantly reduced. As can be seen from Comparative Example 4 and Example 1, the incorporation of nano-aluminum oxide cannot well improve the grindability of the coal gangue, which is mainly because the C / Al composite can form nano-materials during the co-combustion of the coal gangue under high temperature conditions, generate heat and a large amount of gas, improve the internal pore structure of the coal gangue, and make it easy to grind, thereby improving the overall structure of the coal gangue and increasing the grindability. As can be seen from Example 1 and Comparative Example 5, the incorporation of fluorite can significantly improve the activity of the coal gangue, although it has little effect on improving the grindability of the coal gangue. This is mainly because fluorite has mineralization effect, can reduce the sintering temperature of the furnace charge, reduce fuel consumption, and promote the formation of tricalcium silicate. As can be seen from Example 1 and Comparative Example 6, the activity of the coal gangue is significantly reduced without CaCO3 and calcium-based additives. This is because calcium carbonate and calcium-based additives can provide a large amount of calcium elements for the coal gangue, increase the calcium-silicon ratio of the coal gangue, increase the concentration of calcium ions in the liquid phase during the cement hydration reaction, accelerate the cement hydration reaction, and is conducive to activity enhancement. As can be seen from Example 1 and Comparative Example 7, rare earth additives are conducive to promoting the activity of the coal gangue. This is because the rare earth additives are conducive to the occurrence of combustion, conducive to the reduction of combustion temperature, increase the rate and intensity of combustion reaction, increase the structural defects and looseness of the reaction product, improve the grindability, and increase the activity of the coal gangue. As can be seen from Example 1 and Comparative Example 8, the addition of potassium permanganate is conducive to activity enhancement and grinding. This is mainly because potassium permanganate can provide oxygen by its own decomposition under high temperature, increase the oxygen content in the reaction system, accelerate the combustion degree of carbon in the coal gangue, increase the internal pore of the powder, and improve the activity. Especially, the addition of potassium permanganate can greatly stimulate the combustion rate and combustion degree of the combustion system by using the promoting effect of the rare earth additives, thereby improving the activity of the coal gangue. As can be seen from Example 1 and Comparative Example 9, the use of iron agent can cause the activity of the coal gangue to decrease. This is because the lack of iron-based additives can reduce the promoting effect on the combustion of the coal gangue, cause the combustion of the coal gangue to be insufficient and incomplete, and also cannot utilize the performance of tetracalcium aluminoferrite, thereby causing the activity of the coal gangue system to decrease.As can be seen from Example 1 and Comparative Example 10, after the absence of zeolite powder, although its specific surface area is not much different from that of Comparative Examples 5-9, its compressive strength and activity index decrease more, which shows that the zeolite powder has limited effect on the grindability of coal gangue, but has greater effect on the activity of coal gangue. The absence of zeolite powder causes a large degree of decrease in the activity of coal gangue. This is mainly because a large amount of light active silica is generated in the combustion reaction process of coal gangue. Because of the small density and light weight, the light active silica is blown away under the action of hot air. However, the zeolite powder itself has a porous structure and can adsorb the generated light active silica, greatly increasing the content of active silica in the system and increasing the activity of the system. More importantly, when the C / Al composite generates light nanometer alumina spheres at high temperature, it will be blown away due to carbon combustion and the action of hot air, thereby reducing the content of nanometer structure materials inside the coal gangue and affecting the activity of the coal gangue (the nanometer structure itself is beneficial to promoting the cement hydration reaction), so the zeolite powder is an essential component. In addition, the absence of zeolite powder cannot improve the overall activity of coal gangue by exciting the activity of the zeolite powder itself through the crystal type transformation of the zeolite powder under high temperature conditions.

Claims

1. A coal gangue activity activator, characterized in that, The coal gangue active activator is prepared by mixing the following components uniformly and then grinding, and the mass fractions of the components are as follows: CaCO320~50 parts, C / Al composite 10~20 parts Zeolite powder 10~20 parts, Iron-based additive 1~5 parts, Calcium-based additive 2~10 parts, Rare earth additive 1~4 parts, KMnO40.5~2 parts, Isobutyl alcohol 1~2 parts, Fatty acid glyceride 4~8 parts, Fluorite 0.5~4 parts. The C / Al composite is a carbon microsphere-indefinite aluminum hydroxide composite prepared under hydrothermal conditions with carbon microspheres as a template and aluminum salt as an aluminum source, wherein C in the carbon microspheres and Al in the aluminum salt 3+ The molar ratio is 1:1 to 1:

3. The rare earth additive is lanthanide series or cerium series mixed with lanthanide series, and the mass percentage of cerium series is not more than 50%.

2. The coal gangue activity activator according to claim 1, characterized in that, The coal gangue active activator is prepared by mixing the following components uniformly and then grinding for 10~20 min.

3. The coal gangue activity activator according to claim 1, characterized in that, The CaCO3 particle size is 200 mesh~400 mesh. The zeolite powder particle size is 150 mesh~400 mesh.

4. The coal gangue activity activator according to claim 1, characterized in that, The calcium-based additive is one or both of CaCl2 or CaSO4 mixed in any ratio.

5. The coal gangue activity activator according to claim 1, characterized in that, The iron-based additive is one or both of Fe2O3 or FeCl3 mixed in any ratio.

6. A preparation method of active coal gangue powder based on the coal gangue active activator according to any one of claims 1 to 5, comprising the following steps: (1) crushing and grinding the coal gangue to a specific surface area of not less than 100 m 2 / kg, then mixing and stirring with the coal gangue activity activator described above, and then burning; (2) grinding the mixed coal gangue after combustion in step (1) to obtain active coal gangue powder; The coal gangue active activator accounts for 5%~12% of the mass of the coal gangue in step (1).

7. The method of claim 6, wherein the active coal gangue powder is prepared by the steps of: The coal gangue in step (1) is a coal gangue block that has not undergone spontaneous combustion during coal production. ​ 8. The method of claim 7, wherein the active coal gangue powder is prepared by the steps of: The coal gangue combustion temperature in step (1) is 400~900℃, and the combustion time is not less than 3 h. ​ The coal gangue after the addition of the coal gangue activity activator in step (2) is ground after combustion, and the specific surface area is not less than 400 m 2 / kg.

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