Processing technology of solid waste coal gangue powder, powder and application

Abstract

The invention discloses a processing technology of solid waste coal gangue powder, which comprises the following steps: S1, crushing and grinding coal gangue to obtain coal gangue powder; s2, coal gangue powder enters a preheater through a feeder and then enters a heat treatment furnace to be subjected to high-temperature heat treatment, small-particle-size powder enters a cyclone powder collector along with high-temperature gas to be collected, powder is obtained after cooling, and other-particle-size powder is discharged out of the heat treatment furnace through an overflow opening to be collected. Heat energy of the coal gangue is utilized, natural gas is matched for auxiliary combustion, the coal gangue powder can be rapidly dehydrated, decarbonized, activated and whitened in a high-temperature fluidization state, the production period is short, the quality is stable, and high efficiency and energy conservation are achieved. The prepared powder can be respectively used in the fields of cement, ceramics, electroceramics, glass fibers and the like through coal gangue raw material selection and heat treatment temperature regulation and control, the market popularization value is high, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to a processing technology of solid waste coal gangue powder, the powder and application thereof, and relates to CO4B, and specifically to the fields of lime, ceramics and other materials. Background Art

[0002] Gangue is solid waste discharged during coal mining and coal preparation. The utilization rate of gangue is not high, but gangue contains high silicon and aluminum elements. After fine processing, gangue can be used as raw materials for the preparation of cement, ceramics, electric porcelain and other materials. However, the traditional processing technology of gangue has problems such as long processing cycle, high energy consumption, low powder activity and poor quality stability. Therefore, it is very important to develop a processing technology with short production cycle, high thermal utilization rate, stable powder quality and wide process adaptability.

[0003] Chinese invention patent CN03154421.5 discloses a rapid circulation fluidized calcination process and equipment for ultrafine kaolin. The kaolin raw powder of the present invention is preheated; after preheating, it is fed into the lower part of the fluidized calcination furnace, and fuel is introduced into the furnace at the same time; the preheated primary air is fed into the wind chamber at the bottom of the furnace and the fuel is burned in the furnace and a reducing atmosphere calcination zone is formed at its lower part, and the calcined kaolin is discharged into the cyclone cooling system for cooling; after cooling, the ultrafine kaolin powder is obtained by mixing and grinding and depolymerization. It has the characteristics of large operating flexibility, small flow resistance, and low kinetic energy consumption, but the procurement cost of kaolin is high and the raw material requirements are strict. Chinese invention patent CN201610117182.X discloses a method for preparing kaolin from coal gangue, and the processing process is optimized to solve the problem that the carbon is difficult to remove during the calcination process, resulting in insufficient whiteness of the product; only a small amount of high-quality titanium dioxide is added to improve the whiteness of the overall kaolin product, but titanium dioxide needs to be introduced during the processing, which increases the production cost. Summary of the invention

[0004] In order to expand the adaptability of coal gangue raw materials, shorten the processing cycle, and improve the stability of powder quality, the first aspect of the present invention provides a processing technology for solid waste coal gangue powder, comprising the following steps:

[0005] S1 crushes and grinds the coal gangue to obtain coal gangue powder;

[0006] S2 feeds the gangue powder into the preheater through the feeder, and then into the heat treatment furnace for high-temperature heat treatment. The small-sized powder is collected by the cyclone powder collector along with the high-temperature gas, and the powder is obtained after cooling. The remaining particle size powder is discharged and collected through the overflow port in the heat treatment furnace.

[0007] As a preferred implementation, the kaolinite phase in the coal gangue mineral phase is not less than 70wt%, and the loss on ignition of the coal gangue is not higher than 40wt%.

[0008] As a preferred implementation, the kaolinite phase in the coal gangue mineral phase is not less than 80wt%, and the loss on ignition of the coal gangue is not higher than 30wt%.

[0009] As a preferred embodiment, the kaolinite phase in the coal gangue mineral phase is not less than 90wt%, and the loss on ignition of the coal gangue is not higher than 25wt%.

[0010] As a preferred implementation, the aluminum oxide content in the coal gangue is not less than 20wt%, and the iron oxide content is not more than 0.8wt%.

[0011] As a preferred implementation, the aluminum oxide content in the coal gangue is not less than 30wt%, and the iron oxide content is not more than 0.5wt%.

[0012] As a preferred implementation, the iron oxide content in the coal gangue is not higher than 0.4wt%.

[0013] During the experiment, the inventor found that by using coal gangue with a metakaolinite phase, a powder with high quality and whiteness can be obtained, and the loss on ignition is moderate and the impurity content is low. The reason may be: the coal gangue with a metakaolinite phase has low iron ore or other impurity content, and the formed powder quality is better. The low loss on ignition of coal gangue facilitates rapid dehydration and decarbonization during high-temperature heat treatment, and reduces the heat treatment temperature and time. On the contrary, if the loss on ignition is too high, the amount of residual carbon in the coal gangue is large and the organic matter is more. It is not easy for carbon and organic matter to be completely removed at low temperatures, resulting in prolonged heat treatment time, reduced whiteness and activity, and affecting the performance of the powder. And the high loss on ignition, the combustion of a large amount of carbon and organic matter contained therein will cause large fluctuations in the temperature and atmosphere in the furnace, thereby affecting the sintering performance of the product.

[0014] As a preferred embodiment, the particle size of the coal gangue powder after grinding in step S1 is less than 200 meshes.

[0015] As a preferred implementation, the particle size of the coal gangue powder after grinding in step S1 is less than 300 meshes.

[0016] The particle size of the powder of the present invention is less than 300 meshes, and the decarbonization and impurity removal effects of coal gangue are better under the heat treatment process, and the prepared powder has high whiteness and high activity. In addition, the material with a particle size of less than 300 meshes has good fluidization effect in the heat treatment furnace and high heat treatment efficiency.

[0017] As a preferred embodiment, the preheater includes a first preheater and a second preheater, the temperature of the first preheater is 200-350°C, and the temperature of the second preheater is 400-600°C.

[0018] As a preferred embodiment, the preheater includes a first preheater and a second preheater, the temperature of the first preheater is 250-300°C, and the temperature of the second preheater is 450-550°C.

[0019] As a preferred embodiment, the preheater includes a first preheater and a second preheater, the temperature of the first preheater is 300°C, and the temperature of the second preheater is 500°C.

[0020] As a preferred implementation manner, the residence time of the coal gangue powder in the first preheater is 5-10 s, and the residence time of the coal gangue powder in the second preheater is 5-10 s.

[0021] As a preferred implementation manner, the residence time of the coal gangue powder in the first preheater is 6-9 s, and the residence time of the coal gangue powder in the second preheater is 5-8 s.

[0022] As a preferred implementation manner, the residence time of the coal gangue powder in the first preheater is 8 seconds, and the residence time of the coal gangue powder in the second preheater is 5 seconds.

[0023] As a preferred embodiment, the temperature of the cyclone powder collector is 700-950°C.

[0024] As a preferred embodiment, the temperature of the cyclone powder collector is 750-850°C.

[0025] As a preferred embodiment, the temperature of the cyclone powder collector is 800°C.

[0026] As a preferred embodiment, the heat treatment temperature of the heat treatment furnace is 750-1150° C., and the heat treatment time is 30-120 s.

[0027] As a preferred embodiment, the heat treatment temperature of the heat treatment furnace is 1000-1100° C., and the heat treatment time is 80-100 s.

[0028] As a preferred implementation manner, the heat treatment temperature of the heat treatment furnace is 1050° C., and the heat treatment time is 90 seconds.

[0029] As a preferred implementation, the heat treatment furnace is a suspension furnace.

[0030] The gangue powder enters the preheater through the feeder for preheating and dehydration, and then enters the heat treatment furnace for high-temperature heat treatment to decarbonize and remove impurities. The small-sized powder enters the cyclone powder collector with the high-temperature gas and is collected after cooling. The remaining particle size powder is discharged and collected through the bottom overflow port as the powder concentration continues to increase in the heat treatment furnace.

[0031] The applicant further discovered that dynamic heat treatment at 750-1150°C for 30-120s in a suspension furnace can produce a powder with good impurity removal effect, higher whiteness and activity. The reason is that dynamic heat treatment can fully treat the powder at an appropriate temperature, maintain a lower treatment temperature and a shorter treatment time, prevent major changes in the mineral phase structure of the coal gangue, and ensure sufficient impurity removal.

[0032] As a preferred embodiment, the heat treatment furnace uses coal gangue spontaneous combustion, natural gas as auxiliary fuel, regulates the temperature in the furnace, adopts strong oxidizing atmosphere incineration in the furnace, and operates at a slight negative pressure (-1000Pa to -100Pa). The high-pressure wind at the bottom of the heat treatment furnace comes from the high-temperature exhaust gas discharged by the cyclone powder collector, and the secondary combustion air comes from the hot air after the heat exchange of the high-temperature exhaust gas. The temperature of the secondary combustion air is 200-300°C. The gas flow rate in the furnace is regulated according to the particle size and residence time of the material, and the gas flow rate in the furnace is 0.05-0.5m / min.

[0033] The second aspect of the present invention provides a solid waste coal gangue powder, which is prepared by the processing technology of the present invention, wherein the Al2O3 content of the solid waste coal gangue powder is ≥35wt%, and the whiteness of the solid waste coal gangue powder is ≥70%.

[0034] The third aspect of the present invention provides an application of solid waste coal gangue powder, wherein the solid waste coal gangue powder is used in the preparation of cement active additives, ceramics, electric porcelain, and glass fiber.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The processing technology of solid waste coal gangue powder of the present invention utilizes the thermal energy of coal gangue itself and is combined with natural gas to assist combustion. The coal gangue powder can be rapidly dehydrated, decarbonized, activated, and whitened under high-temperature fluidization. The production cycle is short, the quality is stable, and it is highly efficient and energy-saving.

[0037] (2) The processing technology of solid waste coal gangue powder described in the present invention adopts a suspension furnace as a heat treatment furnace and a suspension fluidized calcination process, which can improve the exchange capacity between the material and the hot gas, make full use of the waste heat of the coal gangue itself, and improve the heat utilization efficiency.

[0038] (3) The processing technology of solid waste coal gangue powder described in the present invention has a short residence time of the powder in the heat treatment furnace, high production efficiency, and easy to achieve automatic temperature adjustment in the furnace, thereby avoiding the influence of temperature fluctuations caused by changes in the calorific value and loss on ignition of coal gangue on the stability of product quality to the greatest extent.

[0039] (4) The processing technology of solid waste coal gangue powder of the present invention has wide adaptability to coal gangue raw materials and low processing cost, which is only about 60% of the traditional rotary kiln calcination process. The prepared powder has stable performance and minimizes the phenomenon of raw burning or over-burning.

[0040] (5) The processing technology of solid waste coal gangue powder described in the present invention can prepare powder that can be used in cement, ceramics, electric porcelain, glass fiber and other fields by selecting coal gangue raw materials and regulating heat treatment temperature. It has great market promotion value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the process flow chart of heat treatment of coal gangue;

[0042] Figure 2 This is the XRD diffraction analysis curve of the coal gangue powder prepared in Example 1.

[0043] In the figure: 1. feeder; 2. first preheater; 3. second preheater; 4. heat treatment furnace; 5. cyclone powder collector; 6. overflow port.

[0044] Figure 3 This is the XRD diffraction analysis curve of the coal gangue powder prepared in Comparative Example 1. DETAILED DESCRIPTION

[0045] Example 1

[0046] A processing technology for solid waste coal gangue powder comprises the following steps:

[0047] S1 crushes and grinds the coal gangue to obtain coal gangue powder;

[0048] S2 passes the gangue powder into the preheater through the feeder 1, and then into the heat treatment furnace 4 for high temperature heat treatment. The small-sized powder is collected by the cyclone powder collector 5 along with the high-temperature gas, and the powder is obtained after cooling. The remaining particle size powder is discharged and collected through the overflow port 6 in the heat treatment furnace. The XRD diffraction analysis curve of the formed gangue powder is shown in Figure 1 .

[0049] The kaolinite phase in the coal gangue mineral phase accounts for 91wt%, and the loss on ignition of the coal gangue is 23.4wt%.

[0050] The aluminum oxide content in the coal gangue is 33.68wt%, and the iron oxide content is 0.34wt%. The coal gangue is the coal gangue of Huadian Coal Mine.

[0051] The particle size of the coal gangue powder after grinding in the step S1 is less than 300 meshes.

[0052] The preheater comprises a first preheater 2 and a second preheater 3, the temperature of the first preheater is 300°C, and the temperature of the second preheater is 500°C.

[0053] The residence time of the gangue powder in the first preheater is 8 seconds, and the residence time of the gangue powder in the second preheater is 5 seconds.

[0054] The temperature of the cyclone powder collector is 800°C.

[0055] The heat treatment temperature of the heat treatment furnace is 950° C., and the heat treatment time is 120 seconds.

[0056] The heat treatment furnace is a suspension furnace.

[0057] Example 2

[0058] A processing technology for solid waste coal gangue powder, the specific implementation method is the same as Example 1, the difference is that the heat treatment temperature of the heat treatment furnace is 1050°C, and the heat treatment time is 90s.

[0059] Example 3

[0060] A processing technology for solid waste coal gangue powder comprises the following steps:

[0061] S1 crushes and grinds the coal gangue to obtain coal gangue powder;

[0062] S2 passes the gangue powder into the preheater through the feeder 1, and then into the heat treatment furnace 4 for high-temperature heat treatment. The small-sized powder is collected by the cyclone powder collector 5 along with the high-temperature gas, and the powder is obtained after cooling. The remaining particle size powder is discharged and collected through the overflow port 6 in the heat treatment furnace.

[0063] The kaolinite phase in the coal gangue mineral phase accounts for 70wt%, and the loss on ignition of the coal gangue is 38.6wt%.

[0064] The coal gangue has an aluminum oxide content of 24.6wt% and an Fe2O3 content of 0.68wt%. The coal gangue is acid-thorned ditch coal gangue.

[0065] The particle size of the coal gangue powder after grinding in the step S1 is less than 300 meshes.

[0066] The preheater comprises a first preheater 2 and a second preheater 3, the temperature of the first preheater is 300°C, and the temperature of the second preheater is 500°C.

[0067] The residence time of the gangue powder in the first preheater is 8 s, and the residence time of the gangue powder in the second preheater is 8 s.

[0068] The temperature of the cyclone powder collector is 800°C.

[0069] The heat treatment temperature of the heat treatment furnace is 800° C., and the heat treatment time is 90 seconds.

[0070] The heat treatment furnace is a suspension furnace.

[0071] Example 4

[0072] A processing technology for solid waste coal gangue powder, the specific implementation method is the same as Example 3, the difference is that the heat treatment temperature of the heat treatment furnace is 950°C and the heat treatment time is 90s.

[0073] Example 5

[0074] A processing technology for solid waste coal gangue powder, the specific implementation method is the same as Example 3, the difference is that the heat treatment temperature of the heat treatment furnace is 1100°C and the heat treatment time is 60s.

[0075] Comparative Example 1

[0076] A processing technology for solid waste coal gangue powder, the specific implementation method is the same as Example 3, the difference is that the heat treatment temperature of the heat treatment furnace is 1200°C and the heat treatment time is 60s.

[0077] Comparative Example 2

[0078] A processing technology for solid waste coal gangue powder, the specific implementation method is the same as Example 3, the difference is that the heat treatment temperature of the heat treatment furnace is 1150°C, and the heat treatment time is 30 minutes.

[0079] The heat treatment furnace is a rotary kiln.

[0080] Performance Testing

[0081] 1.Al2O3 content is tested by X-ray fluorescence spectrometer;

[0082] 2. The whiteness is tested using the general method for whiteness determination of inorganic chemical products GB / T23774-2009;

[0083] 3.COD is determined by the COD value of fiber glass raw materials and batch materials in JC / T2156-2012;

[0084] 4. The loss on ignition is determined by the high temperature loss on ignition method, which tests the mass loss rate of the material at a high temperature of 1000°C.

[0085] The test results are shown in Table 1.

[0086] Table 1

[0087] <![CDATA[Al2O3 content (wt%)]]> Whiteness(%) COD(mg / kg) Loss on ignition (%) Example 1 42.86 81 150 2 Example 2 43.24 86 77.5 1.5 Example 3 37.12 46 523 3.15 Example 4 37.64 76 234 2.12 Example 5 37.82 84 174 1.18 Comparative Example 1 38.12 87 57 0.97 Comparative Example 2 38.06 80 108 1.01

[0088] The main mineral phases of Example 1 are kaolinite, alumina spinel and a small amount of quartz, and do not contain mullite phase ( Figure 2 ), the powder has good sintering activity and can be used in ceramics, electrical porcelain and glass fiber and other fields.

[0089] The mineral phase of Example 2 is mainly silicon-aluminum spinel, a small amount of mullite phase (≤10wt%) and quartz. The powder can be used in the fields of ceramics, electrical porcelain and the like.

[0090] The main mineral phase of Example 3 is metakaolinite phase, which has good adsorption and reaction activity. The powder can be used as a cement active additive.

[0091] The main mineral phases of Example 4 are kaolinite, silica-alumina spinel and a small amount of quartz phase. The powder has a high aluminum content, good whiteness and high-temperature sintering activity, and can replace kaolin, Datong clay and some other high-aluminum raw materials for use in ceramics, electrical porcelain, glass fiber and other fields.

[0092] The main mineral phases of Example 5 are silica-alumina spinel, quartz and mullite phases. The powder has a high aluminum content, good whiteness and high-temperature sintering activity, and low high-temperature ignition loss. It can partially replace kaolin, Datong clay, bauxite and other raw materials and be used in ceramics, electrical porcelain, glass fiber and other fields.

[0093] Comparative Example 1 The main mineral phases are amorphous phase, quartz and a large amount of mullite phase. Although the powder has a high aluminum content and good whiteness, the mullite content in the mineral phase is high (about 30wt%) ( Figure 3 ) has poor sintering activity and cannot meet the application requirements in fields such as glass fiber and electrical porcelain.

[0094] The main mineral phases of Comparative Example 2 are silicon aluminum spinel, mullite and quartz. Although the powder obtained has good whiteness, it does not meet the raw material performance requirements in the fields of electrical porcelain and glass fiber due to the presence of a large amount of mullite phase.

Claims

1. A process for processing solid waste coal gangue powder, characterized in that: The following steps are involved: S1 crushes and grinds the coal gangue to obtain coal gangue powder; S2 feeds the gangue powder into the preheater through the feeder, and then into the heat treatment furnace for high-temperature heat treatment. The small-sized powder is collected by the cyclone powder collector along with the high-temperature gas, and the powder is obtained after cooling. The remaining particle size powder is discharged and collected through the overflow port in the heat treatment furnace.

2. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The kaolinite phase in the coal gangue mineral phase is not less than 70wt%, and the ignition loss of the coal gangue is not higher than 40wt%.

3. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The aluminum oxide content in the coal gangue is not less than 20wt%, and the iron oxide content is not more than 0.8wt%.

4. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The particle size of the coal gangue powder after grinding in step S1 is less than 200 meshes.

5. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The preheater comprises a first preheater and a second preheater, the temperature of the first preheater is 200-350°C, and the temperature of the second preheater is 400-600°C.

6. The processing technology of solid waste coal gangue powder according to claim 5, characterized in that: The residence time of the gangue powder in the first preheater is 5-10s, and the residence time of the gangue powder in the second preheater is 5-10s.

7. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The temperature of the cyclone powder collector is 700-950°C.

8. The processing technology of solid waste coal gangue powder according to claim 1, characterized in that: The heat treatment temperature of the heat treatment furnace is 750-1150° C., and the heat treatment time is 30-120 seconds.

9. A solid waste coal gangue powder, characterized in that: The solid waste coal gangue powder is prepared by the processing technology described in any one of claims 1 to 8, wherein the Al2O3 content of the solid waste coal gangue powder is not less than 35wt%, and the whiteness of the solid waste coal gangue powder is not less than 70%.

10. An application of the solid waste coal gangue powder according to claim 9, characterized in that: The solid waste coal gangue powder is used in preparing cement active additives, ceramics, electric porcelain and glass fiber.

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