High whiteness material and its preparation method and application

Abstract

The embodiment of the application discloses a high-whiteness material and a preparation method and application thereof.A preparation method of a high-whiteness material takes low-iron coal gangue powder, dolomite powder and quartz powder as raw materials, and after mixing, the obtained mixed powder is placed in a rotary kiln or a fluidized bed furnace kiln to be dried and calcined under an oxygen atmosphere condition.The application provides a new method for large-scale utilization of low-iron coal gangue, realizes solid waste resource utilization, and can also provide a new technical approach for application of the low-iron coal gangue calcination preparation high-whiteness material in the papermaking industry, the rubber and plastic industry and the coating industry.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of comprehensive utilization of solid waste, in particular to a high-whiteness material and a preparation method and application thereof. BACKGROUND

[0002] Coal gangue is a solid waste discharged in the process of coal mining and coal washing, and is a black gray rock with low carbon content and harder than coal, which is associated with coal seam in the process of coal formation. It includes tunneling gangue in the process of tunneling, gangue mined from the roof / floor and interlayer in the process of mining, and washing gangue picked up in the process of coal washing. It is a kind of solid waste in mining industry. Coal gangue is a mixture of carbonaceous, argillaceous and sandy shale, with carbon content of 20%-30%, low calorific value, and part of which contains humic acid. At present, coal gangue is mainly used for producing cement clinker, concrete lightweight aggregate, bricks, clay refractory bricks and other building materials; in addition, it can also be used for recovering coal, mixed burning of coal and gangue for thermal power generation, and extracting valuable and rare metals from coal gangue with high alumina content, and coal gangue powder can also be used to prepare soil conditioner. However, in general, the utilization of coal gangue is insufficient in strength, the technology is imperfect, the regional development is unbalanced, and other problems, and the comprehensive utilization of coal gangue resources has not been fully realized on a large scale.

[0003] From the composition, coal gangue mainly contains clay minerals (such as kaolinite, montmorillonite, etc.), quartz, carbonate minerals, and a small amount of sulfides and organic matter, etc. Among them, organic matter and part of impurities are the main factors affecting the whiteness of coal gangue. Studies have shown that during the calcination process of coal gangue, organic matter will be oxidized and decomposed at high temperature, releasing carbon dioxide, water vapor and other gases; but part of the impurity minerals will also undergo chemical reaction or phase change, for example, the iron-containing impurities in coal gangue will be oxidized to deep-colored ferric oxide at high temperature, significantly reducing the whiteness of the calcined product, and thus limiting its application range. In addition, there is also a process of using a sagger device to directly calcine low-iron coal gangue in a tunnel kiln to prepare high-whiteness calcined kaolin. Although this method can obtain calcined products with high whiteness, it has the outstanding problems of easy agglomeration leading to uneven particle size, high energy consumption, low efficiency and high calcination cost, which also restricts the large-scale utilization of low-iron coal gangue.

[0004] CN90108197.3 discloses that coal gangue is used to produce active slag on a blast furnace, which takes coal gangue and limestone (or dolomite) as raw materials, and sequentially carries out raw material crushing, weighing and batching, blast furnace smelting and slagging, and slag water quenching. The 28-day compressive strength of the obtained finished product mixed with 30% slag is greater than 85%, which meets the performance of general slag and can be used as a mixing material of cement. The product produced is active slag, which generally has no specific requirements for the whiteness performance of the material. The patent does not involve the whiteness performance of the slag product and the description of the use as a related mineral material filler.

[0005] CN104150497A discloses a method for preparing ultra-high whiteness calcined kaolin from full coal gangue, which takes full coal gangue as raw material, and carries out flameless calcination in an ultra-long calcination kiln for more than 6 hours at a temperature of 945-950℃. The whiteness of the obtained calcined kaolin can reach 95 or more, and the abrasion value and 325-mesh screen residue are lower than those of calcined kaolin produced by other methods. Although the prepared calcined kaolin has high whiteness, it has the problems of easy agglomeration leading to uneven particle size, high energy consumption, low efficiency, and high calcination cost. SUMMARY

[0006] To this end, the embodiments of the present application provide a high-whiteness material and a preparation method and application thereof.

[0007] To achieve the above object, the embodiments of the present application provide the following technical solutions.

[0008] According to a first aspect of the embodiments of the present application, a preparation method of a high-whiteness material is provided, which takes low-iron coal gangue powder, dolomite powder and quartz powder as raw materials, and carries out drying and calcination in an oxygen atmosphere after mixing the obtained mixed powder in a rotary kiln or fluidized bed furnace kiln.

[0009] Further, the weight percentage content of the low-iron coal gangue powder is 60-95%, the weight percentage content of the dolomite powder is 1-20%, and the weight percentage content of the quartz powder is 1-20%.

[0010] Further, the drying condition is 50-100℃ for 2-3 hours, and the calcination condition is a temperature of 960-1050℃ for 2-6 hours.

[0011] Further, the fineness size of the low-iron coal gangue powder, the dolomite powder and the quartz powder is less than 200 mesh.

[0012] Further, the low-iron coal gangue fine powder has the following chemical composition requirements: after the raw material fine powder is calcined at 1000 DEG C for 3 hours, the mass percentage of SiO2 is 30-65%, the mass percentage of Al2O3 is 30-50%, the mass percentage of Fe2O3 is 0.1-1%, the mass percentage of TiO2 is 0.1-3%, the mass percentage of CaO is 0.1-1%, the mass percentage of K2O and Na2O is less than 2%, and the total content of other impurities is less than 2%.

[0013] Further, the white cloud stone fine powder has the following chemical composition requirements: after the raw material fine powder is calcined at 1000 DEG C for 3 hours, the mass percentage of CaO is 35-65%, the mass percentage of MgO is 20-50%, and the total content of other impurities is less than 2%.

[0014] Further, the SiO2 in the quartz fine powder is greater than or equal to 98%, and the total content of impurities is less than 2%.

[0015] According to a second aspect of the embodiments of the present application, the present application provides a high-whiteness material prepared by the method according to any one of the above.

[0016] According to a third aspect of the embodiments of the present application, the present application provides the application of the high-whiteness material according to the above in the papermaking industry, the rubber and plastic industry, and the paint industry.

[0017] The sintered material provided by the present application has high whiteness, can provide a good base color for paint, enhance hiding power, and can replace part of expensive white pigments such as titanium dioxide in white or light-colored paint, thereby reducing the cost of paint while maintaining the appearance quality. In addition, the sintered material has more stable chemical properties and is not easy to react in acid and alkali and other chemical media, and has good corrosion resistance. Compared with traditional fillers such as kaolin, the particle size distribution is more uniform, which helps the powder to be better dispersed in the paint and fill the voids of the matrix, thereby improving the density and mechanical properties of the paint. Using coal gangue to produce paint raw materials by sintering can not only effectively utilize waste resources and reduce environmental pollution, but also reduce the cost of raw materials for paint production. Compared with traditional kaolin calcined by tunnel kiln, the cost of paint prepared by using coal gangue calcined by a rotary kiln can be reduced by about 30%-50%.

[0018] The embodiments of the present application have the following advantages:

[0019] The present application takes low-iron coal gangue fine powder as the main raw material, and by mixing a certain amount of dolomite fine powder and quartz fine powder, the overall whiteness is improved to realize performance improvement. The dolomite fine powder is converted into calcium oxide and magnesium oxide after calcination, and if the calcination temperature is uneven and the local temperature is relatively high, calcium feldspar phase may also be generated. The above calcination products all have high whiteness. The quartz fine powder has high whiteness after calcination, and at the same time, it will swell in volume and produce a cracking effect during high-temperature calcination, thereby avoiding the agglomeration phenomenon of coal gangue fine powder and dolomite fine powder during calcination. The combined effect of these can not only improve the whiteness of calcined coal gangue fine powder, but also avoid agglomeration and improve product performance.

[0020] The raw material cost of the coal gangue fine powder, dolomite fine powder and quartz fine powder used in the present application is low, and the high-whiteness material prepared by high-temperature sintering has the characteristics of low production technical requirement, low production cost and excellent performance. Through reasonable sintering process and formula design, the material can be used as a filler with excellent performance and low cost, and has a broad application prospect in the field of coatings. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be obtained from the provided drawings without creative labor.

[0022] Figure 1 The sample appearance diagram provided by the present application example 1;

[0023] Figure 2 The sample appearance diagram provided by the present application example 2;

[0024] Figure 3 The sample appearance diagram provided by the present application example 3. DETAILED DESCRIPTION

[0025] The embodiments of the present application will be described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present description. Obviously, the described examples are part of the examples of the present application, not all. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] Example 1

[0027] The embodiment provides a high-whiteness material, and a preparation method thereof comprises the following steps:

[0028] (1) Raw materials

[0029] Low-iron coal gangue fine powder: produced in Shanxi, and a fineness size is less than 200 meshes; after the raw material fine powder is calcined at 1000 DEG C for 3 hours, main components of the fine powder are as follows: SiO2 62.08%; Al2O3 32.63%; Fe2O3 0.53%; TiO2 0.63%; CaO 0.92%; K2O+Na2O 1.84%; and total content of other impurities is 1.37%.

[0030] Dolomite fine powder: produced in Shanxi, and a fineness size is less than 200 meshes; after the raw material fine powder is calcined at 1000 DEG C for 3 hours, components of the fine powder are as follows: CaO 57.03%, MgO 41.19%, and total content of other impurities is 1.78%.

[0031] Quartz fine powder: produced in Shanxi, and a fineness size is less than 200 meshes; components of the fine powder are as follows: SiO2 98.24%, and total content of other impurities is 1.76%.

[0032] (2) Mixing: 6 kg of low-iron coal gangue fine powder, 2 kg of dolomite fine powder and 2 kg of quartz fine powder are weighed, and then the fine powders are uniformly mixed by using a fine powder mixing machine.

[0033] (3) Drying: the uniformly mixed material is placed in a rotary kiln to be dried until the water content is less than 1%; generally, the material is dried at 50 DEG C for 3 hours, and then the temperature is increased to 100 DEG C to dry the material for another 3 hours. In order to prevent the mixed fine powders from being agglomerated after drying, the obtained material is passed through a sieve with a mesh size of less than 200.

[0034] (4) Calcining: the obtained powder is increased to 900 DEG C at a temperature increasing rate of 10 DEG C / min, and then increased to 1300 DEG C at a temperature increasing rate of 5 DEG C / min; the powder is sintered and formed at 1300 DEG C and kept for 3 hours; after natural cooling, the powder with good dispersity is obtained, and an appearance diagram is shown in Figure 1 The whiteness of the obtained powder is 89 by detection of a whiteness meter (WSB-2 of Shanghai Xirui Instrument Co., Ltd.).

[0035] Embodiment 2

[0036] The embodiment provides a high-whiteness material, and a preparation method thereof comprises the following steps:

[0037] (1) Raw materials

[0038] Low-iron coal gangue fine powder: produced in Shanxi, fineness size less than 200 mesh, after calcination of raw material fine powder at 1000℃ for 3 hours, its composition is as follows: SiO2 59.07%; Al2O3 35.73%; Fe2O3 0.54%; CaO 0.87%; TiO2 0.63%; K2O+Na2O 1.64%, total content of other impurities 1.52%.

[0039] Dolomite fine powder: produced in Shanxi, fineness size less than 200 mesh, after calcination of raw material fine powder at 1000℃ for 3 hours, its composition is as follows: CaO 59.14%, MgO 39.23%, total content of other impurities 1.63%.

[0040] Quartz fine powder: produced in Shanxi, fineness size less than 200 mesh, its composition is as follows: SiO2 98.48%, total content of other impurities 1.52%.

[0041] (2) Mixing: 7 kg of low-iron coal gangue fine powder, 2 kg of dolomite fine powder, and 1 kg of quartz fine powder are weighed and uniformly mixed by a fine powder mixing machine;

[0042] (3) Drying: the uniformly mixed material is placed in a rotary kiln for drying until the water content is less than 1%, and the general drying conditions are 50℃ drying for 3 hours, and then drying at 100℃ for 3 hours. In order to prevent the mixed fine powder from forming a lump after drying, the obtained material is passed through a sieve with a mesh size less than 200.

[0043] (4) Calcination: the obtained powder is heated at a rate of 10℃ / min to 900℃, and then heated at a rate of 5℃ / min to 1200℃, sintered and formed at 1200℃ for 3 hours, and then naturally cooled to obtain a powder with good dispersibility, and the appearance diagram is shown in Figure 2 The obtained powder has a whiteness of 87 detected by a whiteness meter (Shanghai Xirui Instrument Co., Ltd., WSB-2).

[0044] Example 3

[0045] The present embodiment provides a high-whiteness material, and a preparation method thereof includes the following steps:

[0046] (1) Raw materials

[0047] Low-iron coal gangue fine powder: produced in Inner Mongolia, fineness size less than 200 mesh, after calcination of raw material fine powder at 1000℃ for 3 hours, its composition is as follows: SiO2 54.76%; Al2O3 41.43%; Fe2O3 0.48%; CaO 0.54%; TiO2 0.53%; K2O+Na2O 1.14%, total content of other impurities 1.12%.

[0048] Dolomite fine powder: produced in Hebei, fineness size less than 200 mesh, after calcination at 1000℃ for 3 hours, the composition of the raw material fine powder is as follows: CaO 61.44%, MgO 37.22%, and the total content of other impurities is 1.34%.

[0049] Quartz fine powder: produced in Hebei, fineness size less than 200 mesh, the composition is as follows: SiO298.07%, and the total content of other impurities is 1.93%.

[0050] (2) Mixing: 8 kg of low-iron coal gangue fine powder, 1 kg of dolomite fine powder, and 1 kg of quartz fine powder are weighed and uniformly mixed by a fine powder mixing machine;

[0051] (3) Drying: the uniformly mixed material is placed in a rotary kiln for drying until the water content is less than 1%, and the general drying conditions are 50℃ drying for 3 hours, and then drying at 100℃ for 3 hours. In order to prevent the mixed fine powder from forming a lump after drying, the obtained material is passed through a sieve with a mesh size of less than 200.

[0052] (4) Calcination: the obtained powder is heated at a rate of 10℃ / min to 900℃, and then heated at a rate of 5℃ / min to 1100℃, sintered and shaped at 1100℃ for 3 hours, and then naturally cooled to obtain a powder with good dispersibility, and the appearance diagram is shown in Figure 3 . The obtained powder has a whiteness of 85 detected by a whiteness meter (Shanghai Xirui Instrument Co., Ltd., WSB-2).

[0053] Comparative Example 1

[0054] This comparative example provides a high-whiteness material, which is different from Example 1 in that no dolomite fine powder and quartz fine powder are added, and only low-iron coal gangue is calcined, and the preparation method comprises the following steps:

[0055] (1) Low-iron coal gangue fine powder: the same as Example 1.

[0056] (2) Drying: the low-iron coal gangue fine powder is dried at 100℃ for 24 hours, and the obtained material is passed through a sieve with a mesh size of less than 200;

[0057] (3) Calcination: the obtained powder is heated at a rate of 10℃ / min to 900℃, and then heated at a rate of 5℃ / min to 1300℃, and then kept at 1300℃ for 3 hours, and then naturally cooled to obtain a material with a certain agglomeration phenomenon, and the obtained material has a whiteness of 84 detected by a whiteness meter (Shanghai Xirui Instrument Co., Ltd., WSB-2).

[0058] Comparative Example 2

[0059] The comparative example 1 provides a whiteness material, which is different from the example 1 in that the dolomite fine powder is replaced by the limestone fine powder, and the quartz fine powder is not added, and the preparation method comprises the following steps:

[0060] (1) Raw materials:

[0061] Low-iron coal gangue fine powder: same as the example 1.

[0062] Limestone fine powder: produced in Shanxi, the calcium oxide content of the raw material fine powder after calcination at 1000 ℃ for 3 hours is CaO 97.27%, and the total content of other impurities is 2.73%.

[0063] (2) Mixing: 7 kg of low-iron coal gangue fine powder and 3 kg of limestone fine powder are weighed and uniformly mixed by a fine powder mixer;

[0064] (3) Drying: same as the example 1;

[0065] (4) Sintering: the obtained mixed powder is raised to 900 ℃ at a temperature raising rate of 10 ℃ / min, and then raised to 1300 ℃ at a temperature raising rate of 5 ℃ / min, and kept at 1300 ℃ for 3 h, and the material after natural cooling has a certain agglomeration phenomenon.

[0066] Since the limestone fine powder is easy to discolor under outdoor conditions, the whiteness of the material is unstable, and the impurities of the limestone fine powder also affect the whiteness of the calcined material. The whiteness of the obtained material is 81 detected by a whiteness meter (Shanghai Xirui Instrument Co., Ltd., WSB-2).

[0067] Although the present application has been fully described in the foregoing by way of general description and specific embodiments, modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of the present application claimed.

Claims

1. A method for the production of a high whiteness material, characterized in that, The low-iron coal gangue fine powder, the dolomite fine powder and the quartz fine powder are mixed, and the obtained mixed fine powder is placed in a rotary kiln or a fluidized bed furnace kiln to be dried and calcined under an oxygen atmosphere; the low-iron coal gangue fine powder accounts for 60-95% by weight, the dolomite fine powder accounts for 1-20% by weight, and the quartz fine powder accounts for 1-20% by weight; the drying condition is 50-100℃ for 2-3 hours; the calcining condition is 960-1050℃ for 2-6 hours. The chemical composition requirement of the low-iron coal gangue fine powder is that, after the raw material fine powder is calcined at 1000℃ for 3 hours, it contains SiO2 30-65%, Al2O3 30-50%, Fe2O3 0.1-1%, TiO2 0.1-3%, CaO 0.1-1%, K2O and Na2O each ≤2%, and other impurities with a total content of not more than 2%, all by mass percentage.

2. The method of claim 1, wherein the high brightness material is prepared by a process comprising: The fineness size of the low-iron coal gangue fine powder, the dolomite fine powder and the quartz fine powder is less than 200 mesh.

3. The method of claim 1, wherein the high brightness material is prepared by a process comprising: The chemical composition requirement of the dolomite fine powder is that, after the raw material fine powder is calcined at 1000℃ for 3 hours, it contains CaO 35-65%, MgO 20-50%, and other impurities with a total content of not more than 2%, all by mass percentage.

4. The method of claim 1, wherein the high brightness material is prepared by a process comprising: The SiO2 content in the quartz fine powder is ≥98%, and the total impurity content is not more than 2%. ​ 5. A high whiteness material characterized in that, It is made by the method of any one of claims 1-4.

6. The application of the high-whiteness material of claim 5 in the papermaking industry, the rubber and plastic industry, and the paint industry.

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