Method for producing alumina clinker by using cement clinker calcining kiln

Abstract

The invention discloses a method for producing alumina clinker by using a cement clinker calcining kiln, which comprises the following steps: feeding a raw material for extracting alumina from fly ash by using a limestone sintering method into the cement clinker calcining kiln for sintering so as to produce the alumina clinker; in the cement clinker calcining kiln, the gradient of a fixed bed of a grate cooler blanking chamber is 13-17 degrees; a plurality of air cannons are arranged at the bottom of the grate cooler discharging chamber, and a movable pushing device is arranged at the head end of the grate cooler discharging chamber. The sintering temperature is 1300 DEG C to 1400 DEG C; the sintering time is 20 to 40 minutes; a sintering system is in a reducing atmosphere, and the content of carbon monoxide in a smoke chamber at the tail of the rotary kiln is larger than or equal to 8500 MMP. The cement plant clinker kiln is used for sintering the alumina clinker, the application range of the cement plant clinker kiln is further expanded, and the utilization efficiency of the cement plant clinker kiln is improved. Under the practical conditions that the cement market is increasingly shrunk and the cement production line is low in operation efficiency, the efficiency of the cement production line is fully exerted, and the process investment for producing aluminum oxide by a limestone sintering method is reduced.

Description

Technical Field

[0001] The present invention relates to a method for producing alumina clinker using a cement clinker calcination kiln, and belongs to the technical field of alumina production. Background Art

[0002] With the rapid development of China's economy, the demand for metallic aluminum has increased rapidly. Due to the characteristics of metallic aluminum such as light weight, high strength, corrosion resistance, good electrical and thermal conductivity, good plasticity, and recyclability, it is called a green metal and has a wide range of applications in the national economy and social life. In 2024, China's electrolytic aluminum output was 44 million tons, while the demand for alumina reached more than 85 million tons. Although China is a major alumina producer, bauxite is not abundant. In 2024, the imported bauxite volume reached 158.8 million tons, and the external dependence on bauxite reached more than 70.0%. To ensure the safety of China's aluminum industry, it is necessary to rely on domestic resources and research and develop alternative resources for bauxite.

[0003] High-aluminum fly ash, due to its high alumina content, generally has an alumina content of more than 32.0% in ordinary fly ash, and can reach more than 50.0% in some cases. It is an ideal mineral for replacing bauxite that is hard to come by.

[0004] Domestic research on extracting alumina from high-aluminum fly ash has been carried out for a long time and in-depth, and fruitful results have been achieved. The technology of extracting alumina from fly ash by the limestone sintering method has been verified through a large number of laboratory tests and semi-industrial production. It is currently the most industrialized and large-scale popularized process for extracting alumina from high-aluminum fly ash.

[0005] Compared with other technologies for extracting alumina from high-aluminum fly ash, such as the acid method, the acid-base combined method, the alkali-lime sintering method, etc., the limestone sintering method has the following advantages: rich raw material sources, only limestone + fly ash, can achieve dry sintering, low energy consumption, and the tail slag can be used as raw material for cement plants, realizing the full utilization of waste residues. It is an energy-saving and environmentally friendly process for extracting alumina from fly ash.

[0006] The core of the production process of the limestone sintering method is the calcination of clinker. The investment in the clinker calcination kiln accounts for about 40.0% of the total investment in extracting alumina from fly ash by the limestone sintering method, and the operating cost accounts for about 45.0% of the overall production cost. Based on the current increasing demand for alumina, without building a new clinker calcination kiln, how to further expand the production capacity of extracting alumina from fly ash by the limestone sintering method has become an urgent technical problem to be solved. Summary of the Invention

[0007] The object of the present invention is to provide a method for producing alumina clinker using a cement clinker calcination kiln. By simply modifying the cement clinker production kiln, the cement clinker calcination kiln is used to replace the limestone sintering method clinker calcination kiln to achieve the purpose of producing alumina clinker.

[0008] The technical solution of the present invention: A method for producing alumina clinker using a cement clinker calcination kiln, feeding the raw materials for extracting alumina from fly ash by the limestone sintering method into the cement clinker calcination kiln for sintering, thereby producing alumina clinker; in the cement clinker calcination kiln, the fixed bed slope of the grate cooler feeding chamber is 13° - 17°; a plurality of air cannons are arranged at the bottom of the grate cooler feeding chamber, and a movable pusher device is arranged at the head end of the grate cooler feeding chamber; sintering temperature: 1300°C - 1400°C; sintering time: 20 minutes - 40 minutes; the sintering system is a reducing atmosphere, and the carbon monoxide content in the tail gas chamber of the rotary kiln is ≥8500MMP.

[0009] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the cement clinker calcination kiln is a dry process cement clinker kiln, and the dry process cement clinker kiln includes a raw material batching system, a raw meal grinding device, a raw meal homogenization silo, a preheater, a rotary kiln, and a grate cooler.

[0010] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the raw materials consist of raw meal and mineralizer CSO. The raw meal includes limestone: 62.0% - 67.0%, high-aluminum fly ash: 27.0 - 32.0%, and carbide slag: 3.0% - 10.0%; the dosage of the mineralizer CSO is 3% - 10% of the raw meal amount.

[0011] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the index requirements for the mineralizer CSO are: SO3 content > 45.0%, CaO content > 32.0%, and the contents of Fe2O3 and TiO2 are both < 1.0%.

[0012] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the index requirements for the high-aluminum fly ash are: Al2O3 content > 36.0%, A / S > 0.7, Fe2O3 content < 5.0%, and the contents of TiO2 and MgO are both < 1.0%; The index requirements for the limestone are: SiO2 content < 4.50%, CaO content > 50.0%, and the contents of Fe2O3, TiO2, and MgO are all < 1.0%; The index requirements for the carbide slag are: SiO2 content < 6.50%, CaO content > 65.0%, and the contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0013] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the raw materials are fed into a raw material grinding device and ground into raw meal with a residue on a 180-mesh sieve of less than 5.0%.

[0014] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, the movable pusher device includes a pusher block disposed above the fixed bed in the discharge chamber of the grate cooler. The back of the pusher block is connected to the output end of a hydraulic cylinder. The hydraulic cylinder is fixed on the equipment platform. The hydraulic cylinder is connected to a hydraulic station via a hydraulic oil pipe. An opening through which the pusher block can extend is provided on the side wall of the discharge chamber of the grate cooler at the head end of the fixed bed.

[0015] In the aforementioned method for producing alumina clinker using a cement clinker calcination kiln, a neutron meter is provided on the raw material batching system.

[0016] In the extraction of alumina from fly ash by the limestone sintering method, high-aluminum fly ash is proportioned with limestone. The raw meal is calcined in a clinker kiln. The sintered clinker is leached with a sodium carbonate solution. The leaching solution is subjected to solid-liquid separation. After the filter residue is washed, it is sent to a cement production line and used as a raw material. The filtrate is subjected to carbonation to obtain crude aluminum hydroxide. The crude aluminum hydroxide is then subjected to desilication, leaching, and seeding to produce metallurgical-grade alumina products.

[0017] The main features of this process are as follows: Dry sintering can be adopted, and the sintering energy consumption is relatively low. The produced tail slag, silicon-calcium slag, can be used as a raw material for cement production. It is currently the production technology with the most promising industrial application prospects.

[0018] The current equipment process of the alumina clinker calcination kiln: 1. The raw materials for alumina production are mixed in a certain proportion through a batching system and then fed into a vertical raw material grinding mill for raw material grinding.

[0019] 2. The raw meal ground to a certain fineness requirement is fed into a raw material homogenization silo, and the homogenization of the raw meal is completed in the raw material silo.

[0020] 3. The homogenized raw meal is fed into a cyclone preheater for preheating. The preheater is divided into five stages in total. In the preheater, the raw meal and the flue gas perform countercurrent heat exchange. The high-temperature flue gas coming from the kiln is cooled after heat exchange and enters the induced draft fan; after passing through the five-stage preheater, the raw meal is heated from room temperature to 820 °C and enters the rotary kiln.

[0021] 4. Calcination in the kiln: Calcination temperature: 1350 °C ± 50 °C; Residence time of the calcined material in the kiln: 20.0 minutes - 35.0 minutes.

[0022] The atmosphere in the kiln is controlled as a reducing atmosphere, and the carbon monoxide content in the smoke chamber at the kiln tail is ≥ 8500 PPM.

[0023] 5. The clinker after calcination enters the cooling system. The alumina clinker kiln uses a single-cylinder cooler to cool the clinker. The temperature of the clinker out of the single-cylinder cooler is ≤ 200 °C.

[0024] Principle and equipment process of cement clinker calcination: The principle of cement production is as follows: Raw materials such as limestone, clay, iron ore, and fly ash are proportioned according to a certain ratio to prepare qualified raw meal; after grinding, the raw meal with a certain fineness is sent to the clinker kiln for calcination, and the calcination temperature is generally 1450 °C. Clinker composed of tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite and other phases is produced. After the calcined clinker is cooled by the cooling system, it becomes the finished sintered clinker; the cooling system is generally a grate cooler. The specific production process is as follows: 1. The raw materials for cement production are mixed in a proportion by the batching system and then enter the vertical raw mill for grinding of the raw meal.

[0025] 2. The raw meal ground by the raw mill into raw meal powder with a certain fineness requirement is sent to the raw meal homogenization silo, and the homogenization of the raw meal is completed in the raw meal silo.

[0026] 3. The homogenized raw meal is sent to the cyclone preheater for preheating. The preheater is divided into five stages in total. The raw meal and flue gas in the preheater are in countercurrent heat exchange. The high-temperature flue gas coming from the kiln is cooled after heat exchange and then enters the induced draft fan; after passing through the five-stage preheater, the raw meal is heated from room temperature to 880 °C and enters the rotary kiln.

[0027] 4. Calcination in the kiln: Calcination temperature: 1400 °C ± 50 °C; Residence time of the calcined material in the kiln: about 15.0 minutes.

[0028] The atmosphere in the kiln is controlled as an oxidizing atmosphere, and the oxygen content in the kiln tail smoke chamber is ≥ 1.0%.

[0029] 5. The clinker after calcination enters the cooling system. Generally, a grate cooler is used in the cement kiln to cool the clinker. The temperature of the clinker out of the grate cooler is ≤ 100 °C.

[0030] The basic characteristics of the new dry process cement clinker kiln: 1. High thermal efficiency: The new dry process kiln adopts the five-stage suspension preheating and precalcination technology outside the kiln, which enables the raw meal to be fully preheated and partially decomposed before entering the kiln, can effectively utilize the heat generated by fuel combustion, and has a high thermal efficiency. Generally, it saves 20% - 30% of fuel compared with the wet process kiln.

[0031] 2. High production capacity: Since the preheating and decomposition processes are completed in the preheater and decomposer outside the kiln, and the main process in the kiln is the burning of clinker, the production capacity of the kiln is greatly improved, and large-scale production can be achieved. At present, the daily output of a single new dry process cement kiln can reach thousands of tons or even tens of thousands of tons.

[0032] 3. Stable clinker quality: During the dry process of calcination, the raw meal is in full contact with the hot gas stream, with high heat transfer efficiency and uniform heating of the material, which is conducive to the formation of clinker minerals and can produce clinker with stable quality. At the same time, precise batching and advanced firing control technologies also help to improve the uniformity and stability of the clinker.

[0033] 4. Excellent environmental protection performance: The new dry-process cement kiln is equipped with efficient dust collection equipment, which can effectively reduce dust emissions and environmental pollution. In addition, by optimizing combustion technology and adopting environmental protection measures such as denitrification, the emissions of harmful gases such as nitrogen oxides can also be reduced.

[0034] 5. High degree of automation: The dry-process cement production process widely uses an automated control system, which can monitor and precisely control parameters such as the temperature, pressure, and flow rate of the kiln in real time, realizing automated operation of the production process, reducing manual intervention, improving production efficiency and the stability of product quality, and at the same time reducing labor intensity.

[0035] Through research and analysis, we found that these characteristics of the cement clinker calcination kiln highly coincide with the technical requirements of the limestone sintering method for extracting alumina clinker, and have natural replaceability; by improving some key links, it is completely possible to replace the limestone sintering method clinker kiln for calcining alumina clinker. At present, for cement production, due to the slowdown of real estate and infrastructure construction, the cement production is in a state of overcapacity. The production of cement kilns has to adopt flexible production, with the annual operating time between 40.0% - 65.0%, and in some areas it is even less than 30.0%, resulting in long-term idle of cement kilns. If the clinker kiln for cement production can be used to replace the clinker calcination kiln for extracting alumina by the limestone sintering method, it can not only greatly reduce the investment in the process of extracting alumina by the limestone sintering method, but also make full use of the off-season flexible production period of the cement clinker kiln to produce alumina clinker, further expanding the production capacity of extracting alumina from high-aluminum fly ash by the limestone sintering method, and also improving the utilization rate of the cement kiln and reducing the comprehensive production cost, achieving mutual benefit and win-win results.

[0036] The present invention aims at the process of extracting alumina from high-aluminum fly ash by the limestone sintering method. By comparing and analyzing the processes and equipment of the cement clinker calcination kiln, and through simple transformation of the cement production clinker kiln, the cement production clinker calcination kiln is used to replace the limestone sintering method clinker kiln to achieve the purpose of producing alumina clinker.

[0037] The present invention uses the cement clinker sintering kiln to replace the limestone sintering method clinker sintering kiln for sintering alumina clinker, expanding the production range of the cement kiln, improving the utilization efficiency of the cement kiln, and reducing the production cost of extracting alumina from high-aluminum fly ash by the limestone sintering method.

[0038] Compared with the prior art, the present invention has the following advantages: 1. The present invention uses the clinker kiln of the cement production line to replace the clinker sintering kiln of the limestone sintering method, successfully sinters qualified alumina clinker, and achieves good results of continuous and stable operation.

[0039] 2. After the present invention raises the fixed bed angle of the discharge chamber of the cement clinker sintering grate cooler by 1.0° - 5.0°, during the alumina clinker sintering process, the high-temperature clinker can flow smoothly on the fixed bed of the grate cooler, avoiding the accumulation of high-temperature clinker on the fixed bed of the grate cooler.

[0040] 3. The present invention adds 6 - 8 air cannons and movable pusher devices to the discharge chamber of the cement clinker sintering production line grate cooler, which plays a good role in pushing the accumulated material on the fixed grate bed, effectively prevents the accumulation of high-temperature materials at the discharge port, and realizes the continuous and stable operation of the grate cooler.

[0041] 4. The present invention realizes the controllability of the sintering time during the alumina clinker sintering process by adjusting the rotation speed of the clinker kiln of the cement production line, meeting the technical requirements for alumina clinker sintering.

[0042] 5. The present invention realizes the generation of a reducing atmosphere during the sintering process by adjusting the air-coal ratio of the kiln in the cement clinker production line, meeting the control requirements for the reducing atmosphere in alumina clinker sintering.

[0043] 6. Through the analysis of the dissolution rate of the alumina clinker sintered by the cement clinker kiln production line, the dissolution rate of alumina reaches more than 70.0%, and the highest exceeds 80.0%, achieving the goal that the cement production line clinker kiln can completely produce qualified alumina clinker.

[0044] 7. The present invention uses the cement plant clinker kiln to replace the clinker sintering kiln of the limestone sintering method for sintering alumina clinker, further expanding the application range of the cement plant clinker kiln and improving the utilization efficiency of the cement plant clinker kiln. In the current situation where the cement market is shrinking and the operation efficiency of the cement production line is low, it is of great significance for giving full play to the efficiency of the cement production line, reducing the process investment in alumina production by the limestone sintering method, and improving the benefits of alumina production by extracting from fly ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic structural diagram of an alumina clinker calcination kiln; Figure 2 is a schematic structural diagram of a cement clinker calcination kiln; Figure 3 is a schematic structural diagram of a movable pusher device; Figure 4 is the Figure 3 top view structural diagram of the appendix.

[0046] Reference numerals: 1 - pusher block, 2 - hydraulic cylinder, 3 - equipment platform, 3 - hydraulic oil pipe, 5 - hydraulic station, 6 - snowman structure, 7 - fixed bed. Specific embodiments

[0047] The present invention will be further described below in conjunction with the drawings and embodiments, but it shall not be used as a basis for limiting the present invention.

[0048] Embodiment of the present invention: A method for producing alumina clinker using a cement clinker calcination kiln, in which the raw materials for extracting alumina from fly ash by the limestone sintering method are fed into the cement clinker calcination kiln for sintering, thereby producing alumina clinker.

[0049] In the cement clinker calcination kiln, the slope of the fixed bed in the grate cooler discharge chamber is increased by 1° - 5° and adjusted to 13° - 17° to increase the smoothness of alumina clinker discharging. 6 - 8 air cannons are added at the bottom of the grate cooler discharge chamber according to a certain distribution shape, and a movable pusher device is arranged at the head end of the grate cooler discharge chamber to prevent the accumulation of clinker in the discharge chamber. Since the viscosity of alumina clinker is greater than that of cement clinker, the fluidity of alumina clinker is relatively poor. Therefore, the above structural improvements are made to the cement clinker calcination kiln.

[0050] Sintering temperature: 1300°C - 1400°C; sintering time: 20 minutes - 40 minutes; the sintering system is a reducing atmosphere, and the carbon monoxide content in the tail gas chamber of the rotary kiln is ≥8500MMP to meet the sintering requirements of alumina clinker.

[0051] The cement clinker calcination kiln is a dry process cement clinker kiln, which includes a raw material batching system, a raw meal grinding device, a raw meal homogenization silo, a preheater, a rotary kiln, and a grate cooler. Among them, the raw materials for producing alumina clinker are mixed in a certain proportion by the raw material batching system and then fed into the vertical raw meal grinding device for grinding. The raw meal grinding device grinds the raw materials into raw meal powder with a certain fineness requirement and sends it into the raw meal homogenization silo, where the homogenization of the raw meal is completed. The homogenized raw meal is sent to the cyclone preheater for preheating. The preheater is divided into five stages. The raw meal and flue gas in the preheater are in countercurrent heat exchange. The high-temperature flue gas coming from the rotary kiln is cooled after heat exchange and enters the induced draft fan; after passing through the five-stage preheater, the raw meal is heated from room temperature to a certain temperature and then enters the rotary kiln. The calcination temperature in the rotary kiln: 1300°C - 1400°C; the residence time of the calcined material in the kiln: 20 - 40 minutes. Adjust the air - coal ratio of the clinker kiln in the cement production line to control the sintering system as a reducing atmosphere, so that the carbon monoxide content in the tail gas chamber of the rotary kiln is ≥8500MMP. The clinker discharged from the rotary kiln enters the grate cooler for cooling.

[0052] The raw materials consist of raw meal and mineralizer CSO. The raw meal includes limestone: 62.0% - 67.0%, high-aluminum fly ash: 27.0 - 32.0%, and carbide slag: 3.0% - 10.0%. The dosage of mineralizer CSO is 3% - 10% of the amount of raw meal.

[0053] The index requirements for the mineralizer CSO are as follows: SO3 content > 45.0%, CaO content > 32.0%, and the contents of Fe2O3 and TiO2 are both < 1.0%.

[0054] The index requirements for the high-aluminum fly ash are as follows: Al2O3 content > 36.0%, A / S > 0.7, Fe2O3 content < 5.0%, and the contents of TiO2 and MgO are both < 1.0%. The index requirements for the limestone are as follows: SiO2 content < 4.50%, CaO content > 50.0%, and the contents of Fe2O3, TiO2, and MgO are all < 1.0%. The index requirements for the carbide slag are as follows: SiO2 content < 6.50%, CaO content > 65.0%, and the contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0055] The raw materials are fed into a raw mill to grind the raw meal out of the mill to a fineness with a residue on a 180-mesh sieve less than 5.0%, so that the raw materials can be evenly mixed in the raw meal homogenizing silo and are convenient for calcination.

[0056] The movable pusher device includes a pusher block 1 arranged above a fixed bed 7 in the discharge chamber of the grate cooler. The back of the pusher block 1 is connected to the output end of a hydraulic cylinder 2. The hydraulic cylinder 2 is fixed on an equipment platform 3. The hydraulic cylinder 2 is connected to a hydraulic station 5 through a hydraulic oil pipe 4. An opening for the pusher block 1 to extend into is provided on the side wall of the discharge chamber 8 of the grate cooler at the head end of the fixed bed 7. Since the alumina clinker has relatively greater viscosity compared to cement clinker, the alumina clinker discharged from the rotary kiln is likely to accumulate on the fixed bed 7 in the discharge chamber of the grate cooler to form a snowman structure 6. At this time, the flow of the alumina clinker can be realized through an air cannon and a pusher device to achieve the cooling of the clinker. During the use of the pusher device, when the snowman structure 6 appears, the hydraulic cylinder 2 drives the pusher block 1 to push out, and the pusher block 1 pushes the snowman structure 6 to make it flow along the fixed bed 7.

[0057] A neutron gauge is provided on the raw material batching system. Installing the neutron gauge can monitor and adjust the preparation of the raw meal in real time to ensure the qualification of the raw meal ratio.

[0058] In order to verify whether the method of the present invention is feasible, the following experiment is specifically conducted:

[0059] The equipment requirements are as follows: 1. Raise the fixed bed slope of the cooler discharge chamber in the cement clinker sintering production line by 2.0° to reach 14°, enabling the smooth discharge of high-temperature clinker on the fixed bed of the cooler during the alumina clinker sintering process, and avoiding the accumulation of high-temperature clinker on the fixed bed of the cooler.

[0060] 2. Add 8 air cannons at the bottom of the cooler discharge chamber in the cement clinker sintering production line, and set up a movable pusher device at the head end of the cooler discharge chamber, which plays a good role in pushing the accumulated material on the fixed grate bed, effectively preventing the accumulation of high-temperature materials at the discharge port, and realizing the continuous and stable operation of the cooler.

[0061] Raw material requirements: Mineralizer CSO index requirements: SO3 content = 47.83%; CaO content = 33.48%; the contents of Fe2O3, TiO2, etc. are all less than 1.0%.

[0062] High-aluminum fly ash: Al2O3 content = 39.03%; A / S = 0.7; Fe2O3 content = 4.85%; the contents of TiO2, MgO, etc. are all less than 1.0%.

[0063] Limestone index requirements: SiO2 content = 4.38%; CaO content = 51.89%; the contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0064] Calcium carbide slag index requirements: SiO2 content = 6.48%; CaO content = 65.48%; the contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0065] Process control condition requirements: Raw material ratio control: Limestone: 65.45% + High-aluminum fly ash: 26.89% + Calcium carbide slag: 7.66%; Mineralizer CSO addition amount: 8.0% of the raw material amount.

[0066] Sintering temperature: 1350°C; Clinker kiln rotation speed: 2.5 revolutions per minute; Sintering time: 40 minutes; Carbon dioxide content in the kiln tail smoke chamber: Control at 10000 MMP.

[0067] Grind the sintered clinker of the cement kiln to less than 180 mesh, and dissolve the ground clinker with a 60 g / L sodium carbonate solution.

[0068] Dissolution rate conditions: Liquid-solid ratio of dissolution: 5.0, Dissolution temperature: 75.0°C, Dissolution time: 30.0 minutes. Filter the dissolution solution, analyze Nt and AO in the dissolution filtrate; Wash the dissolution tail slag - calcium silicate slag, and analyze the alumina and calcium oxide contents of the tail slag.

[0069] Calculation of dissolution rate: Dissolution rate of alumina: = 100(1 - (AO in calcium silicate slag / CaO in calcium silicate slag) / (AO in clinker / CaO in clinker)).

[0070] Technical indicators of sintered clinker in cement kiln production line: Clinker pulverization rate: 58.47%; Dissolution rate: 84.61%.

[0071] Equipment requirements are as follows: 1. In the present invention, the slope of the fixed bed in the discharge chamber of the cement clinker sintering grate cooler is raised by 3.0° to reach 15°, enabling smooth discharge of high-temperature clinker on the fixed bed of the grate cooler during the alumina clinker sintering process, and avoiding the accumulation of high-temperature clinker on the fixed bed of the grate cooler.

[0072] 2. Add 8 air cannons at the bottom of the discharge chamber of the grate cooler in the cement clinker sintering production line, and set an active pusher device at the head end of the discharge chamber of the grate cooler, which plays a good role in pushing the accumulated material on the fixed grate bed, effectively preventing the accumulation of high-temperature materials at the discharge port, and realizing the continuous and stable operation of the grate cooler.

[0073] Raw material requirements: Mineralizer CSO index requirements: SO3 content = 49.46%; CaO content = 35.20%; Contents of Fe2O3, TiO2, etc. are all less than 1.0%.

[0074] High-aluminum fly ash: Al2O3 content = 36.97%; A / S = 0.7; Fe2O3 content = 4.56%; Contents of TiO2, MgO, etc. are all less than 1.0%.

[0075] Limestone index requirements referred to in the present invention: SiO2 content = 4.26%; CaO content = 53.19%; Contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0076] Calcium carbide slag index requirements referred to in the present invention: SiO2 content = 5.98%; CaO content = 66.57%; Contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0077] Process control condition requirements: Raw material ratio control: Limestone: 66.95% + High-aluminum fly ash: 27.89% + Calcium carbide slag: 5.16%; Mineralizer CSO addition amount: 5.0% of the raw material amount.

[0078] Sintering temperature: 1380°C; Clinker kiln rotation speed: 5.0 revolutions per minute; Sintering time: 30 minutes; Carbon monoxide content in the kiln tail smoke chamber: Control at 15000 PPM.

[0079] Grind the sintered clinker of the cement kiln to less than 180 mesh, and dissolve the ground clinker with a sodium carbonate solution of 60 g / L.

[0080] Dissolution rate conditions: liquid-solid ratio of the dissolution solution: 5.0, dissolution temperature: 75.0 °C, dissolution time: 30.0 minutes. The dissolution solution is filtered, and the filtered dissolution solution is analyzed for Nt and AO; the dissolution tailings - calcium silicate slag are washed, and the alumina and calcium oxide contents of the tailings are analyzed.

[0081] Calculation of the dissolution rate: Dissolution rate of alumina: = 100(1 - (AO in calcium silicate slag / CaO in calcium silicate slag) / (AO in clinker / CaO in clinker)).

[0082] Technical indicators of cement kiln sintered clinker: clinker pulverization rate: 63.28%; dissolution rate: 77.63%.

[0083] Equipment requirements are as follows: 1. In the present invention, the fixed bed slope of the charging chamber of the cement clinker sintering grate cooler is raised by 5.0° to reach 17°, enabling the smooth feeding of high-temperature clinker on the fixed bed of the grate cooler during the alumina clinker sintering process, and avoiding the occurrence of the accumulation of high-temperature clinker on the fixed bed of the grate cooler.

[0084] 2. Six air cannons are added at the bottom of the charging chamber of the grate cooler in the cement clinker sintering production line, and a movable pusher device is arranged at the head end of the charging chamber of the grate cooler, which plays a good role in pushing the accumulated materials on the fixed grate bed, effectively preventing the accumulation of high-temperature materials at the feeding port, and realizing the continuous and stable operation of the grate cooler.

[0085] Raw material requirements: Requirements for the mineralizer CSO index: SO3 content = 46.33%; CaO content = 32.57%; contents of Fe2O3, TiO2, etc. are all less than 1.0%.

[0086] High-aluminum fly ash: Al2O3 content = 37.38%; A / S = 0.7; Fe2O3 content = 4.38%, and contents of TiO2, MgO, etc. are all less than 1.0%.

[0087] Requirements for limestone index: SiO2 content = 4.45%; CaO content = 53.46%; contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0088] Requirements for carbide slag index: SiO2 content = 6.14%; CaO content = 65.94%; contents of Fe2O3, TiO2, MgO, etc. are all less than 1.0%.

[0089] Requirements for process control conditions: raw material ratio control: limestone: 63.95% + high-aluminum fly ash: 30.42% + carbide slag: 5.99%; addition amount of mineralizer CSO: 3.0% of the raw material amount.

[0090] Sintering temperature: 1330 °C; Rotation speed of the clinker kiln: 8.0 revolutions per minute; Sintering time: 22 minutes; Carbon monoxide content in the flue gas chamber at the kiln tail: Controlled at 12000 PPM.

[0091] The sintered clinker of the cement kiln is ground to less than 180 meshes, and the ground clinker is leached with a sodium carbonate solution of 60 g / L.

[0092] Leaching rate conditions: Liquid-solid ratio of the leaching solution: 5.0, Leaching temperature: 75.0 °C, Leaching time: 30.0 minutes. The leaching solution is filtered, and the leaching filtrate is analyzed for Nt and AO; The leaching tailings - calcium silicate slag are washed, and the alumina and calcium oxide contents of the tailings are analyzed.

[0093] Calculation of the leaching rate: Leaching rate of alumina: = 100(1 - (AO of calcium silicate slag / CaO of calcium silicate slag) / (AO of clinker / CaO of clinker)).

[0094] Technical indicators of the sintered clinker of the cement kiln: Clinker pulverization rate: 96.47%; Leaching rate: 72.83%.

[0095] Combined with the above experimental examples, it can be seen that through the analysis of the leaching rate of the sintered alumina clinker in the cement clinker kiln production line, the leaching rate of alumina reaches more than 70.0%, and the highest exceeds 80.0%, achieving the goal that the clinker kiln of the cement production line can completely produce qualified alumina clinker.

Claims

1. A method for producing alumina clinker using a cement clinker calcining kiln, characterized in that: The raw material of alumina extracted from fly ash by limestone sintering method is sent to cement clinker calcining kiln for sintering, so as to produce alumina clinker; in the cement clinker calcining kiln, the fixed bed slope of the grate cooler discharge chamber is 13°-17°; a plurality of air cannons are arranged at the bottom of the grate cooler discharge chamber, and a movable pushing device is arranged at the head end of the grate cooler discharge chamber; sintering temperature: 1300℃-1400℃; sintering time: 20 minutes-40 minutes; the sintering system is a reducing atmosphere, and the carbon monoxide content in the tail smoke chamber of the rotary kiln is ≥8500MMP.

2. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 1, characterized in that: The cement clinker calcining kiln is a dry process cement clinker kiln, which comprises a raw material batching system, a raw material grinding device, a raw material homogenizing storage, a preheater, a rotary kiln and a grate cooler.

3. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 1, characterized in that: The raw materials are composed of raw meal and mineralizer CSO. The raw meal includes limestone: 62.0%-67.0%, high-alumina fly ash: 27.0-32.0%, and carbide slag: 3.0%-10.0%. The amount of mineralizer CSO is 3%-10% of the raw meal.

4. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 3, characterized in that: The index requirements of the mineralizer CSO are: SO3 content>45.0%, CaO content>32.0%, Fe2O3 and TiO2 content are both <1.0%.

5. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 3, characterized in that: The index requirements of the high-aluminum fly ash are: Al2O3 content>36.0%, A / S>0.7, Fe2O3 content<5.0%, TiO2 and MgO content both<1.0%; The index requirements of the limestone are: SiO2 content <4.50%, CaO content >50.0%, Fe2O3, TiO2, MgO content <1.0%; The index requirements of the carbide slag are: SiO2 content <6.50%, CaO content >65.0%, Fe2O3, TiO2, MgO and other contents are all less than 1.0%.

6. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 2, characterized in that: The raw materials are sent to a raw material mill and ground into a raw material fineness of less than 5.0% residue on a 180-mesh sieve.

7. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 1, characterized in that: The movable material pushing device comprises a material pushing block (1) arranged above a fixed bed (7) in a grate cooler unloading chamber, the back of the material pushing block (1) being connected to an output end of a hydraulic cylinder (2), the hydraulic cylinder (2) being fixed on an equipment platform (3), the hydraulic cylinder (2) being connected to a hydraulic station (5) via a hydraulic oil pipe (4), and an opening into which the material pushing block (1) can extend is arranged on a side wall of the grate cooler unloading chamber at the head end of the fixed bed (7).

8. The method for producing alumina clinker using a cement clinker calcining kiln according to claim 2, characterized in that: The raw material batching system is provided with a neutron meter.

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