A process and system for preparing ceramsite from high calorific value coal gangue

Abstract

The application discloses a kind of process and system suitable for high calorific value coal gangue preparation ceramsite, comprising the following steps: one, high calorific value coal gangue raw material is sent into granulation system and is granulated, and coal gangue ceramsite raw material ball is obtained;Two, coal gangue ceramsite raw material ball is sent into drying machine and is dried, and the moisture after drying is controlled≤2%;Three, the coal gangue ceramsite raw material ball after drying is sent into belt burning equipment, and is removed volatile organic compound and is burned;Four, the coal gangue raw material ball after removing volatile organic compound is sent into rotary short kiln and is calcined at high temperature, and coal gangue ceramsite clinker ball is obtained;Five, after coal gangue ceramsite clinker ball is cooled by grate cooler, coal gangue ceramsite product is obtained.The application connects belt burning equipment and energy-saving rotary short kiln together, effectively removes volatile organic compound in coal gangue and burns it before entering rotary short kiln, reduces the total amount of volatile organic compound in coal gangue ceramsite, and has good social and environmental benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramsite production, in particular to a process and system for preparing ceramsite from high-calorific-value coal gangue. BACKGROUND

[0002] Ceramsite is a kind of artificial lightweight aggregate with light weight, high strength, heat preservation, frost resistance and other multi-functional characteristics, which is prepared from silico-alumina raw materials through batching, balling and high-temperature firing. It is widely used in building materials, gardening, sewage treatment, refractory and thermal insulation materials, chemical industry, petroleum and other fields.

[0003] Coal gangue is a kind of black gray rock with low carbon content and higher hardness than coal, which is generally produced in the production process of coal mining, excavation and the like. Coal gangue contains various minerals, such as kaolinite, quartz, mica, calcite and iron-containing mineral phases, among which quartz and kaolinite are the main mineral components. In addition, coal gangue contains a certain calorific value, and the calorific value range is generally between 50-1600kcal / kg. The volatile VOC volatilization temperature range is generally between 400-550℃. When it is used as cement raw material, if its calorific value is ≥100kcal / kg in the raw material, when the mixing amount is greater than 5%, it will cause the preheater to be blocked, thereby causing the instability of the mud production, and even causing safety accidents. When the calorific value of coal gangue is ≥400kcal / kg, if it is used to prepare ceramsite, because the calorific value is high, when it enters the kiln tail and meets the high temperature above 800℃, the organic volatile VOC contained therein will be released sharply, resulting in the cracking of ceramsite, and part of VOC entering the flue gas treatment system, which brings disposal problems. Especially, the sharp release of VOC will cause coking phenomenon on the surface of ceramsite, which seriously affects the appearance and surface hardness of ceramsite, and causes the instability of product quality.

[0004] In view of the problems of high calorific value and volatile organic matter encountered in the process of preparing ceramsite from high calorific value coal gangue, the prior art, for example, Chinese Patent Publication No. CN116143434A discloses a new method for firing ceramsite from coal gangue and an equipment system thereof, wherein a belt sintering machine is provided, and the belt sintering machine is sequentially divided into a drying and dewatering section, a preheating section, an ignition section, a self-sintering section, a high-temperature sintering section, a cooling section 1, and a cooling section 2. The drying, calcining and cooling processes in the existing firing process are integrated in one equipment. However, due to the large thickness and static sintering of the material, the method is prone to incomplete sintering and over-sintering, and the surface of the ceramsite product is prone to coking, resulting in poor quality stability of the ceramsite product. In addition, when a fault occurs, the static arrangement of the material cannot be unloaded to the rotary kiln and other equipment. In addition, the method burns all the organic combustible materials in the coal gangue pellets and removes the carbon in the coal gangue pellets, the temperature of the coal gangue pellets reaches 1000℃, and only oxygen-containing gas fuel can be used. At present, in order to achieve low-carbon and environmental protection in the process of preparing ceramsite, alternative fuels are mostly used, and therefore the static sintering ceramsite also has the problems of poor fuel adaptability, and the ceramsite particle morphology is not as good as that in the rotary kiln.

[0005] Chinese Patent Publication No. CN114370759A discloses a low-energy-consumption system and process for preparing ceramsite from solid waste, which uses a re-burning furnace to perform high-temperature combustion treatment on waste gas containing volatile organic matter, but results in a large amount of flue gas treatment and a large amount of water vapor, high energy consumption. In addition, the use of kiln head waste heat alone may have insufficient drying capacity. Chinese Patent Publication No. CN114353527A discloses a green calcining system and process for preparing aggregate from solid waste, which uses the heat source at the front end of the cooling machine to directly enter the dryer to dry the ceramsite (the temperature at the front end of the grate cooler is generally higher than 500℃), the waste gas discharged from the dryer is heated and then enters the re-burning furnace as combustion air to burn harmful gas components, and the flue gas after the re-burning furnace enters the heat exchanger to exchange heat with the drying waste gas and then enters the flue gas treatment system. However, the use of high-temperature waste heat at the front end of the cooling machine to dry the ceramsite raw material balls in this patent may cause cracking of the raw material balls. In addition, the drying waste gas also enters the re-burning furnace, resulting in a large amount of flue gas treatment and a large amount of water vapor, high energy consumption. Furthermore, when the water content of the ceramsite raw material is greater than 20%, the use of kiln head waste heat alone may have insufficient drying capacity. Chinese Patent Publication No. CN116462431A discloses a coal gangue thermal activation calcining process and system based on a cement firing system, which uses kiln head waste heat for indirect thermal activation of coal gangue. However, this method has low indirect calcining efficiency and is not suitable for calcining ceramsite containing a certain amount of water.

[0006] At present, the disposal of bulk solid waste is becoming more and more strict, and therefore how to safely and environmentally prepare ceramsite from solid waste and hazardous waste is a technical problem that needs to be urgently solved.

[0007] In summary, the prior art at least has the following technical problems:

[0008] (1) When high-calorific-value coal gangue is used to prepare ceramsite, the existing process cannot produce high-quality high-strength ceramsite with stable product quality because the rapid volatilization of the excessively high calorific value in the kiln will cause widespread coking on the surface of the ceramsite, resulting in blackening of the ceramsite surface, decrease in hardness, increase in water absorption, and different degrees of decrease in physical performance indicators such as bulk density and cylinder pressure strength.

[0009] (2) The static sintering method for preparing coal gangue ceramsite has a large cloth thickness and static sintering, which is prone to incomplete sintering and over-sintering, and the surface of the ceramsite product is prone to coking, resulting in poor quality stability of the ceramsite product. There are also problems such as the inability to unload the material from the static arrangement to devices such as a rotary kiln when a fault occurs. This method can only use oxygen-containing gas fuel, and the static sintering ceramsite also has problems such as poor fuel adaptability and poor particle morphology compared to the optimized morphology in a rotary kiln.

[0010] (3) The unreasonable setting of the secondary combustion chamber or the re-combustion chamber in the process results in the fact that the residual heat at the kiln head and the kiln tail is not fully utilized to meet the drying of the ceramsite green balls, and the volatile VOC and water vapor in the drying process cannot be effectively separated, resulting in high energy consumption, and the risk of VOC entering the flue gas treatment system, which increases environmental disposal costs. In addition, the drying waste gas enters the re-combustion furnace or the secondary combustion chamber without condensation, resulting in a large amount of flue gas treatment and a large amount of water vapor, which is energy-consuming.

[0011] (4) The drying temperature of ceramsite is generally controlled within 300℃, and the use of residual heat (generally higher than 500℃ ceramsite drying temperature) in the front section of the grate cooler directly dries the ceramsite green balls, which is prone to cause the problem of material ball cracking. The residual heat higher than 300℃ will cause the volatile VOC in the coal gangue to volatilize into the waste gas, which will further affect the difficulty of waste gas treatment. SUMMARY

[0012] The present application is to solve the problems existing in the prior art, and provides a process and system for preparing ceramsite from high-calorific-value coal gangue, which is composed of the following parts: a granulating system, a dryer, a belt-type firing device, a rotary short kiln, a grate cooler, a ceramsite finished product warehouse, a heat exchanger, a gas mixer, a condensing system, a water treatment system and a flue gas treatment system.The volatile organic compounds in the high-calorific-value coal gangue ceramsite are volatilized and burned out in the belt-type firing device at a temperature of 600-800 DEG C, so that the volatile organic compounds and organic carbon in the coal gangue are effectively separated, which is beneficial to energy saving and consumption reduction; the flue gas discharged from the kiln tail is heat-exchanged with fresh air in the heat exchanger, and then enters the flue gas treatment system for standard discharge, the gas obtaining heat enters the dryer to dry the coal gangue green balls, the waste gas after drying and removing water enters the condensing system for dust removal and discharge; the fresh air enters the grate cooler as cooling air, and the medium-low temperature waste air obtaining heat in the cooling process enters the gas mixer to mix with fresh air, and then enters the dryer again to dry the ceramsite green balls, and the high-temperature tertiary air obtaining heat enters the belt-type firing device.The belt-type firing device and the energy-saving rotary short kiln are connected in series, so that the volatile organic compounds in the coal gangue are volatilized and burned out before entering the rotary short kiln, the total amount of volatile organic compounds in the coal gangue ceramsite is reduced, the denitration temperature and denitration efficiency of the kiln tail are improved, the kiln tail waste heat and kiln head waste heat are fully utilized through heat exchange, the waste heat temperature entering the dryer is adjusted, and the breakage rate of the ceramsite green balls entering the kiln is reduced.Therefore, the system has good social and environmental benefits.

[0013] The present application is realized by a process for preparing ceramsite from high-calorific-value coal gangue, which comprises the following steps:

[0014] Step one, sending the high-calorific-value coal gangue raw material into the granulating system for granulation to obtain coal gangue ceramsite green balls;

[0015] Step two, sending the coal gangue ceramsite green balls prepared in step one into the dryer for drying, and controlling the moisture content after drying to be less than or equal to 2%;

[0016] Step three, sending the coal gangue ceramsite green balls after drying in step two into the belt-type firing device for removing volatile organic compounds and burning out;

[0017] Step four, sending the coal gangue green balls after removing volatile organic compounds in step three into the rotary short kiln for high-temperature calcination to obtain coal gangue ceramsite clinker balls;

[0018] Step five, cooling the coal gangue ceramsite clinker balls obtained in step four in the grate cooler to obtain coal gangue ceramsite products.

[0019] Preferably, the high-temperature flue gas discharged from the rotary short kiln tail enters the heat exchanger and exchanges heat with fresh air indirectly, the medium-low temperature hot gas after heat exchange is used as drying medium to enter the dryer to dry the coal gangue ceramic raw material balls, and the low-temperature waste heat flue gas after heat exchange enters the flue gas treatment system to meet the emission standard; the medium-high temperature flue gas discharged from the belt firing equipment enters the heat exchanger to exchange heat with fresh air indirectly, or enters the heat exchanger to exchange heat with fresh air indirectly and generate power by waste heat.

[0020] Preferably, the dried waste gas enters the condensing system to remove moisture and is discharged after dust removal.

[0021] Preferably, the fresh air enters the grate cooler as cooling air, the medium-low temperature waste gas after obtaining heat in the cooling process enters the gas mixer to mix with fresh air, and then enters the dryer to dry the ceramic raw material balls, and the high-temperature tertiary air after obtaining heat enters the belt firing equipment.

[0022] Preferably, in step one, the moisture of the obtained coal gangue ceramic raw material balls is controlled at 14-18%.

[0023] Preferably, in step two, when the dryer dries the coal gangue ceramic raw material balls, the drying temperature is controlled at 180-250°C.

[0024] Preferably, in step three, the temperature in the belt firing equipment is controlled at 600-800°C, and the residence time of the ceramic raw material balls is 30-50 min; the belt firing equipment comprises an outer shell, an air inlet and a feeding port are arranged on one side of the top of the outer shell, an air outlet is arranged on one side of the outer shell, a discharging port is arranged on the bottom of the outer shell opposite to the feeding port, 3-8 layers of heat-resistant steel material caterpillar belts which can horizontally roll are arranged in the outer shell, an ignition device, a caterpillar belt transmission control system, a temperature sensor and a pressure sensor are arranged in the outer shell, the thickness of the material layer of each layer of caterpillar belt is 80-200 mm, and the caterpillar belt transmission control system is used to control the residence time of the ceramic raw material balls.

[0025] Preferably, in step three, when the rotary short kiln is high-temperature calcined, the calcination temperature is controlled at 1100-1200°C, the residence time in the kiln is 40-60 min, and the rotation speed of the kiln is 1-3 r / min.

[0026] Preferably, in step five, the bulk density of the coal gangue ceramic product is 750-950 kg / m 3 , the cylinder compressive strength is 8.0-22.4 Mpa, and the 1-hour water absorption rate is 2.6-9.8%.

[0027] A system for preparing ceramsite from high calorific value coal gangue, comprising the following parts: a granulating system, a dryer, a belt type firing device, a rotary short kiln, a grate cooler and a ceramsite finished product warehouse; the material outlet of the granulating system is connected with the material inlet of the dryer, the material outlet of the dryer is connected with the material inlet of the belt type firing device, the material outlet of the belt type firing device is connected with the kiln tail material inlet of the rotary short kiln, the kiln head discharge outlet of the rotary short kiln is connected with the material inlet of the grate cooler, and the material outlet of the grate cooler is connected with the material inlet of the ceramsite finished product warehouse.

[0028] Preferably, the system further comprises a heat exchanger, a gas mixer, a condensing system, a water treatment system, a dust collector and a flue gas treatment system, the gas outlet of the dryer is connected with the inlet of the condensing system, the waste water outlet of the condensing system is connected with the inlet of the water treatment system, the gas outlet of the condensing system is connected with the inlet of the dust collector; fresh air is connected with the cooling air inlet of the grate cooler, the medium-low temperature waste air outlet of the grate cooler is connected with the gas inlet one of the gas mixer, fresh air is connected with the gas inlet two of the gas mixer, the gas outlet of the gas mixer is connected with the gas inlet one of the dryer, the high temperature third air outlet of the grate cooler is connected with the gas inlet of the belt type firing device; the kiln tail flue gas outlet of the rotary short kiln is connected with the gas inlet one of the heat exchanger, fresh air is connected with the gas inlet two of the heat exchanger, the gas outlet one of the heat exchanger is connected with the gas inlet of the flue gas treatment system, and the gas outlet two of the heat exchanger is connected with the gas inlet two of the dryer.

[0029] Further preferably, when the calorific value content of the coal gangue is 400-700 kcal / kg, the flue gas outlet of the belt type firing device is connected with the gas inlet three of the heat exchanger; when the calorific value content of the coal gangue is greater than or equal to 700 kcal / kg, the flue gas outlet of the belt type firing device is respectively connected with the gas inlet three of the heat exchanger and the inlet of a waste heat power generation system; and the gas outlet three of the heat exchanger is connected with the gas inlet of the flue gas treatment system.

[0030] The system has the advantages and positive effects that:

[0031] 1、The present application sets up a belt calcining device as a removal device of VOC in coal gangue, the calcining temperature range of which is 600-800℃, which just covers the temperature range 350-550℃ of volatile VOC volatilization in high calorific value coal gangue, the moisture in the raw ball of coal gangue ceramic granule has been dried to within 2% before entering the belt calcining device, therefore, in the belt calcining device, volatile VOC will volatilize and burn out on the surface of the raw ball of ceramic granule, which is essentially different from the sharp burning in the high temperature section of the kiln tail of the rotary short kiln, the burning at low temperature is only the burning of volatile organic matter, and does not involve the sharp burning of organic carbon, thus, coking phenomenon will not occur. For the coal gangue with heat value content of 400-700kcal / kg, all volatile VOC can be removed by full calcination in the belt calcining device, and the generated heat can be used for drying; for the coal gangue with heat value content of ≥700kcal / kg, all volatile VOC can be removed by full calcination in the belt calcining device, and the generated heat can be partly used for drying, and the other part is sent to waste heat power generation, so as to achieve high efficient utilization of the heat value in coal gangue.

[0032] 2、The present application connects the belt calcining device and the energy-saving rotary short kiln together to form an innovative two-stage calcining process, which provides a brand new system and process for preparing ceramic granule from high calorific value coal gangue, avoids high energy consumption of twice high temperature calcination, and environmental protection and safety problems caused by volatile harmful substances entering the flue gas treatment system; and also creates favorable conditions for SNCR denitration at the kiln tail. Compared with the mode of burning the waste gas again by adding a second combustion chamber at the kiln tail, the system of the present application has remarkable energy-saving effect, and can avoid the generation of dioxin, and has positive environmental protection and economic benefits.

[0033] 3、The belt calcining device provided by the present application can effectively remove volatile VOC in coal gangue, regulate the distribution of internal void structure of ceramic granule, improve the hardness of the surface of raw ceramic granule, reduce the breakage rate of ceramic granule, and increase the temperature of ceramic granule entering the kiln, so that different calorific value coal gangues can be fully and effectively utilized; and the organic carbon in coal gangue will also form part of water gas in the presence of a small amount of water vapor, which can supplement part of heat source when led to the kiln head, and the higher the heat value of coal gangue, the more combustible gas is generated. In addition, the remaining 10% or less organic carbon in coal gangue can also be used as a gas generating material to adjust the internal pore structure of ceramic clinker in the energy-saving rotary short kiln, which is more conducive to regulating the physical properties of ceramic products compared with the traditional mode of completely burning organic matter in coal gangue in a belt sintering machine. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is the process flow chart provided by the embodiment of the present application, which is suitable for preparing ceramic granule from high calorific value coal gangue.

[0035] Figure 2The high-calorific-value coal gangue thermal analysis diagram provided by the embodiment of the present application has a volatile temperature range of 422.36-507.56 DEG C;

[0036] Figure 3 The high-calorific-value coal gangue thermal analysis diagram provided by the embodiment of the present application has a volatile temperature range of 371.84-573.29 DEG C;

[0037] Figure 4 The high-calorific-value coal gangue thermal analysis diagram provided by the embodiment of the present application has a volatile temperature range of 304.54-523.97 DEG C;

[0038] Figure 5 The structure schematic diagram of the belt firing equipment provided by the embodiment of the present application.

[0039] In the figure, 1, air inlet; 2, air outlet; 3, feeding port; 4, discharging port; 5, track; 6, distributor. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0041] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "linking" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, and can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] Please refer to Figure 1 The embodiment of the present application provides a process suitable for preparing haydite from high-calorific-value coal gangue, which comprises the following steps:

[0043] Step one, sending the high-calorific-value coal gangue raw material into a granulation system for granulation to obtain coal gangue haydite raw material balls;

[0044] Step two, sending the coal gangue haydite raw material balls prepared in step one into a dryer for drying, and controlling the moisture content after drying to be ≤2%;

[0045] Step three, sending the coal gangue haydite raw material balls after drying in step two into a belt firing equipment for removing volatile organic compounds and burning off;

[0046] Step four, the coal gangue raw ball after removing volatile organic matter in step three is sent into a rotary short kiln for high-temperature calcination to obtain coal gangue ceramic granule clinker balls;

[0047] Step five, the coal gangue ceramic granule clinker balls obtained in step four are cooled by a grate cooler to obtain coal gangue ceramic granule products.

[0048] As a preferred embodiment, the high-temperature flue gas discharged from the kiln tail of the rotary short kiln enters a heat exchanger to exchange heat with fresh air, the medium-low temperature hot gas after heat exchange is used as drying medium to enter a dryer to dry the coal gangue ceramic raw balls, and the low-temperature waste heat flue gas after heat exchange enters a flue gas treatment system for standard discharge; the medium-high temperature flue gas discharged from the belt firing equipment enters a heat exchanger to exchange heat with fresh air indirectly, or enters a heat exchanger to exchange heat with fresh air indirectly and generates power by waste heat.

[0049] As a preferred embodiment, the waste gas after drying enters a condensing system to remove moisture and is discharged after dust removal.

[0050] As a preferred embodiment, the fresh air enters a grate cooler as cooling air, the medium-low temperature waste air after obtaining heat in the cooling process enters a gas mixer to mix with fresh air and then enters a dryer to dry the ceramic raw balls again, and the high-temperature tertiary air after obtaining heat enters the belt firing equipment.

[0051] As a preferred embodiment, in step one, the moisture of the obtained coal gangue ceramic raw balls is controlled to be 14-18%.

[0052] As a preferred embodiment, in step two, when the dryer dries the coal gangue ceramic raw balls, the drying temperature is controlled to be 180-250℃.

[0053] As a preferred embodiment, in step three, the temperature in the belt firing equipment is controlled to be 600-800℃, and the residence time of the ceramic raw balls is 30-50 min. Figures 2 to 4 The volatilization temperature range of volatile VOC in general coal gangue is illustrated, and thus the suitable calcination temperature of the belt firing equipment is determined. Figure 5 As shown in the figure, the belt firing equipment includes a shell, an air inlet 1 and a feeding port 3 are arranged on one side of the top of the shell, an air outlet 2 is arranged on one side of the shell, a discharging port 4 is arranged on the bottom of the shell on the side opposite to the feeding port 3, 3-8 layers of heat-resistant steel material caterpillar belts 5 that can horizontally roll are arranged in the shell, an ignition device, a caterpillar belt transmission control system, a temperature sensor and a pressure sensor are arranged in the shell, the thickness of the material layer of each layer of caterpillar belts 5 is 80-200 mm, and the caterpillar belt transmission control system is used to control the residence time of the ceramic raw balls.

[0054] As a preferred embodiment, in step three, the calcination temperature of the rotary short kiln is controlled at 1100-1200℃, the residence time in the kiln is 40-60min, and the rotation speed of the kiln is 1-3r / min.

[0055] As a preferred embodiment, in step five, the bulk density of the coal gangue ceramic product is 750-950kg / m 3 , the cylinder compressive strength is 8.0-22.4Mpa, and the 1-hour water absorption rate is 2.6-9.8%.

[0056] A system for preparing ceramic products from high-calorific-value coal gangue, comprising the following parts: a granulation system, a dryer, a belt-type firing device, a rotary short kiln, a grate cooler, and a ceramic product warehouse; the material outlet of the granulation system is connected to the material inlet of the dryer, the material outlet of the dryer is connected to the material inlet of the belt-type firing device, the material outlet of the belt-type firing device is connected to the kiln tail material inlet of the rotary short kiln, the kiln head material outlet of the rotary short kiln is connected to the material inlet of the grate cooler, and the material outlet of the grate cooler is connected to the material inlet of the ceramic product warehouse.

[0057] As a preferred embodiment, the system further comprises a heat exchanger, a gas mixer, a condensation system, a water treatment system, a dust collector, and a flue gas treatment system; the gas outlet of the dryer is connected to the inlet of the condensation system, the wastewater outlet of the condensation system is connected to the inlet of the water treatment system, and the gas outlet of the condensation system is connected to the inlet of the dust collector; fresh air is connected to the cooling air inlet of the grate cooler, the medium-low temperature waste air outlet of the grate cooler is connected to the gas inlet one of the gas mixer, fresh air is connected to the gas inlet two of the gas mixer, the gas outlet of the gas mixer is connected to the gas inlet one of the dryer, and the high-temperature tertiary air outlet of the grate cooler is connected to the gas inlet of the belt-type firing device; the kiln tail flue gas outlet of the rotary short kiln is connected to the gas inlet one of the heat exchanger, fresh air is connected to the gas inlet two of the heat exchanger, the gas outlet one of the heat exchanger is connected to the gas inlet of the flue gas treatment system, and the gas outlet two of the heat exchanger is connected to the gas inlet two of the dryer.

[0058] As a preferred embodiment, when the calorific value content of the coal gangue is 400-700kcal / kg, the flue gas outlet of the belt-type firing device is connected to the gas inlet three of the heat exchanger; when the calorific value content of the coal gangue is ≥700kcal / kg, the flue gas outlet of the belt-type firing device is connected to the gas inlet three of the heat exchanger and the inlet of a waste heat power generation system, respectively; and the gas outlet three of the heat exchanger is connected to the gas inlet of the flue gas treatment system.

[0059] In order to better understand the above-mentioned embodiments of the present application, the following examples further illustrate them with specific raw materials of general solid waste coal gangue, hazardous waste contaminated soil and other raw materials bentonite.

[0060] Example 1

[0061] A process for preparing ceramsite from high-calorific-value coal gangue, comprising the following steps:

[0062] Step one, send the high-calorific-value coal gangue raw material into the granulation system for granulation to obtain coal gangue ceramsite raw material balls, and control the moisture of the raw material balls to be 14%;

[0063] Step two, send the coal gangue ceramsite raw material balls prepared in step one into the dryer for drying, control the drying temperature to be 250℃, and control the moisture after drying to be ≤2%; the waste gas after drying enters the condensing system to remove moisture and is discharged after dust removal;

[0064] Step three, send the coal gangue ceramsite raw material balls after drying in step two into the belt firing equipment, control the temperature in the belt firing equipment to be 600℃, and the residence time of the ceramsite raw material balls to be 50 min, to remove volatile organic compounds and burn them off;

[0065] Step four, send the coal gangue raw material balls after removal of volatile organic compounds in step three into the short rotary kiln for high-temperature calcination, control the calcination temperature to be 1200℃, the residence time in the kiln to be 60 min, and the rotation speed of the kiln to be 1 r / min, to obtain coal gangue ceramsite clinker balls; wherein, the high-temperature flue gas discharged from the tail of the short rotary kiln enters the heat exchanger to exchange heat with fresh air, the medium-low temperature hot gas after heat exchange is used as the drying medium to enter the dryer to dry the coal gangue ceramsite raw material balls, and the low-temperature waste heat flue gas after heat exchange enters the flue gas treatment system for emission in accordance with the standard;

[0066] Step five, after the coal gangue ceramsite clinker balls obtained in step four are cooled by the grate cooler, the coal gangue ceramsite product is obtained, and the bulk density of the coal gangue ceramsite is 750 kg / m 3 , the cylinder compressive strength is 8.0 Mpa, and the 1-hour water absorption rate is 2.6%. Among them, the fresh air enters the grate cooler as cooling air, the medium-low temperature waste gas after obtaining heat in the cooling process enters the gas mixer to mix with fresh air again, and then enters the dryer to dry the ceramsite raw material balls, and the high-temperature tertiary air after obtaining heat enters the belt firing equipment.

[0067] Example 2

[0068] A process for preparing ceramsite from high-calorific-value coal gangue, comprising the following steps:

[0069] Step one, send the high-calorific-value coal gangue raw material into the granulation system for granulation to obtain coal gangue ceramsite raw material balls, and control the moisture of the raw material balls to be 18%;

[0070] Step two, the coal gangue ceramic raw material ball prepared in step one is sent into a drying machine for drying, the drying temperature is controlled at 180℃, and the moisture after drying is controlled at ≤2%; the waste gas after drying is removed of moisture and then discharged after dust removal;

[0071] Step three, the coal gangue ceramic raw material ball after drying in step two is sent into a belt firing device, the temperature in the belt firing device is controlled at 800℃, the residence time of the ceramic raw material ball is 30min, and the volatile organic compounds are removed and burned off;

[0072] Step four, the coal gangue raw material ball after removal of volatile organic compounds in step three is sent into a rotary short kiln for high-temperature calcination, the calcination temperature is controlled at 1140℃, the residence time in the kiln is 40min, and the rotation speed of the kiln is 3r / min, to obtain coal gangue ceramic clinker balls; wherein, the high-temperature flue gas discharged from the kiln tail of the rotary short kiln enters a heat exchanger to exchange heat with fresh air, the medium-low temperature hot gas after heat exchange is used as a drying medium to enter the drying machine to dry the coal gangue ceramic raw material ball, and the low-temperature waste heat flue gas after heat exchange enters a flue gas treatment system for standard discharge;

[0073] Step five, the coal gangue ceramic clinker ball obtained in step four is cooled by a grate cooler to obtain a coal gangue ceramic product, the bulk density of the coal gangue ceramic is 860kg / m 3 , the cylinder compressive strength is 14.6Mpa, and the 1-hour water absorption rate is 9.8%. Among them, the fresh air enters the grate cooler as cooling air, the medium-low temperature waste gas after obtaining heat in the cooling process enters a gas mixer to mix with fresh air and then enters the drying machine again to dry the ceramic raw material ball, and the high-temperature tertiary air after obtaining heat enters the belt firing device.

[0074] Example 3

[0075] A process suitable for preparing ceramic from high-calorific-value coal gangue, comprising the following steps:

[0076] Step one, the high-calorific-value coal gangue raw material is sent into a granulation system for granulation to obtain coal gangue ceramic raw material balls, and the moisture of the raw material ball is controlled at 16%;

[0077] Step two, the coal gangue ceramic raw material ball prepared in step one is sent into a drying machine for drying, the drying temperature is controlled at 220℃, and the moisture after drying is controlled at ≤2%; the waste gas after drying is removed of moisture and then discharged after dust removal;

[0078] Step three, the coal gangue ceramic raw material ball after drying in step two is sent into a belt firing device, the temperature in the belt firing device is controlled at 750℃, the residence time of the ceramic raw material ball is 40min, and the volatile organic compounds are removed and burned off;

[0079] Step four, the coal gangue raw material ball after removing volatile organic matter in step three is sent into a rotary short kiln for high-temperature calcination, the calcination temperature is controlled to be 1175 DEG C, the residence time in the kiln is 50 min, and the rotation speed of the kiln is 2 r / min, so that coal gangue ceramic granule clinker balls are obtained; wherein the high-temperature flue gas discharged from the tail of the rotary short kiln enters a heat exchanger, exchanges heat with fresh air, the medium-low temperature hot gas after heat exchange is used as a drying medium to enter a dryer to dry the coal gangue ceramic raw material balls, and the low-temperature waste heat flue gas after heat exchange is discharged into a flue gas treatment system to meet the discharge standard;

[0080] Step five, the coal gangue ceramic granule clinker balls obtained in step four are cooled by a grate cooler, so that coal gangue ceramic granule products are obtained, the bulk density of the coal gangue ceramic granule is 950 kg / m 3 , the cylinder compressive strength is 22.4 Mpa, and the one-hour water absorption is 4.3%. In the process of cooling, the fresh air enters the grate cooler as cooling air, the medium-low temperature waste gas after heat absorption enters a gas mixer to mix with fresh air again, and then enters the dryer to dry the ceramic raw material balls, and the high-temperature tertiary air after heat absorption enters a belt firing device.

[0081] In summary, the belt firing device and the energy-saving rotary short kiln are connected in series to form an innovative two-stage calcination process, which provides a new system and process for preparing ceramic granules from high-calorific-value coal gangue, avoids high energy consumption of twice high-temperature calcination, and environmental protection and safety problems caused by volatile harmful substances entering the flue gas treatment system; and creates favorable conditions for SNCR denitration at the kiln tail. Compared with the mode of burning the exhaust gas again by adding a second combustion chamber at the kiln tail, the system of the present application has remarkable energy-saving effect, and can avoid the generation of dioxin, and has positive environmental protection and economic benefits.

[0082] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of ceramsite from high calorific value coal gangue, characterized in that, Comprising the following steps: Step one, send high calorific value coal gangue raw material into granulation system for granulation, get coal gangue ceramic aggregate raw material ball; Step two, send the coal gangue ceramic aggregate raw material ball prepared in step one into a dryer for drying, control the moisture after drying ≤2%; Step three, send the coal gangue ceramic aggregate raw material ball after drying in step two into a belt type sintering equipment, remove volatile organic compounds and burn them off, effectively separate volatile organic compounds and organic carbon in coal gangue; wherein the volatile organic compounds will be volatilized and burned on the surface of the ceramic aggregate raw material ball; the organic carbon in the coal gangue forms part of the water gas in the presence of a small amount of water vapor, and supplies part of the heat source to the head of the rotary short kiln; Step four, send the coal gangue raw material ball after removing volatile organic compounds in step three into a rotary short kiln for high temperature calcination, get coal gangue ceramic aggregate clinker ball; Step five, after the coal gangue ceramic aggregate clinker ball obtained in step four is cooled by a grate cooler, obtain the coal gangue ceramic aggregate product.

2. The process according to claim 1, adapted to the preparation of ceramsite from high calorific value coal gangue, characterized by the fact that: The high temperature flue gas discharged from the tail of the rotary short kiln enters the heat exchanger and exchanges heat with fresh air indirectly, the medium and low temperature hot gas after heat exchange is used as drying medium to enter the dryer to dry the coal gangue ceramic aggregate raw material ball, the low temperature waste heat flue gas after heat exchange enters the flue gas treatment system for standard emission; the medium and high temperature flue gas discharged from the belt type sintering equipment enters the heat exchanger and exchanges heat with fresh air indirectly, or enters the heat exchanger and exchanges heat with fresh air indirectly and generates power with waste heat.

3. The process for the preparation of ceramsite from high calorific value coal gangue according to claim 1, characterized in that: The waste gas after drying enters the condensing system to remove moisture and is discharged after dust removal.

4. The process for the preparation of haydite from high calorific value coal gangue according to claim 1, characterized by the fact that: Fresh air enters the grate cooler as cooling air, the medium and low temperature waste gas after obtaining heat in the cooling process enters the gas mixer and mixes with fresh air, and then enters the dryer again to dry the ceramic aggregate raw material ball, the high temperature tertiary air after obtaining heat enters the belt type sintering equipment.

5. The process for the preparation of haydite from high calorific value coal gangue according to claim 1, characterized by the fact that: In step one, the moisture of the obtained coal gangue ceramic aggregate raw material ball is controlled at 14-18%.

6. The process for the preparation of haydite from high calorific value coal gangue according to claim 1, characterized by the fact that: In step two, when the dryer dries the coal gangue ceramic aggregate raw material ball, the drying temperature is controlled at 180-250℃.

7. The process for the preparation of haydite from high calorific value coal rejects, according to claim 1, characterized by the fact that: In step three, the temperature in the belt type sintering equipment is controlled at 600-800℃, and the residence time of the ceramic aggregate raw material ball is 30-50min; the belt type sintering equipment comprises an outer shell, an air inlet and a feeding port are arranged on one side of the top of the outer shell, an air outlet is arranged on one side of the outer shell, a discharging port is arranged on the bottom of the outer shell opposite to the feeding port, 3-8 layers of heat-resistant steel material caterpillar belts which can horizontally roll, an ignition device, a caterpillar belt transmission control system, a temperature sensor and a pressure sensor are arranged in the outer shell, the thickness of the material layer of each layer of caterpillar belt is 80-200mm, and the caterpillar belt transmission control system is used to control the residence time of the ceramic aggregate raw material ball.

8. The process for the preparation of haydite from high calorific value coal rejects, according to claim 1, characterized by the fact that: In step three, when the rotary short kiln is high temperature calcined, the calcination temperature is controlled at 1100-1200℃, the residence time in the kiln is 40-60min, and the rotation speed of the kiln is 1-3 r / min.

9. The process for the preparation of haydite from high calorific value coal rejects, according to claim 1, characterized by the fact that: The bulk density of the coal gangue ceramic product in step five is 750-950 kg / m 3 The cylinder compressive strength is 8.0-22.4 Mpa, and the 1-hour water absorption is 2.6-9.8%.

10. A system adapted to the preparation of ceramsite from high calorific value coal gangue, for the implementation of the process according to any one of claims 1 to 9, characterized in that it comprises: The granulation system, the dryer, the belt type firing equipment, the rotary short kiln, the grate cooler and the ceramsite finished product warehouse are connected.

11. The system adapted for the preparation of ceramsite from high calorific value coal gangue according to claim 10, characterized in that: The heat exchanger, the gas mixer, the condensing system, the water treatment system, the dust collector and the flue gas treatment system are also included. The gas outlet of the dryer is connected with the inlet of the condensing system, the waste water outlet of the condensing system is connected with the inlet of the water treatment system, and the gas outlet of the condensing system is connected with the inlet of the dust collector. Fresh air is connected with the cooling air inlet of the grate cooler, the low-temperature waste air outlet of the grate cooler is connected with the gas inlet one of the gas mixer, fresh air is connected with the gas inlet two of the gas mixer, the gas outlet of the gas mixer is connected with the gas inlet one of the dryer, the high-temperature waste air outlet of the grate cooler is connected with the gas inlet of the belt type firing equipment. The kiln tail flue gas outlet of the rotary short kiln is connected with the gas inlet one of the heat exchanger, fresh air is connected with the gas inlet two of the heat exchanger, the gas outlet one of the heat exchanger is connected with the gas inlet of the flue gas treatment system, and the gas outlet two of the heat exchanger is connected with the gas inlet two of the dryer.

12. The system adapted for the preparation of ceramsite from high calorific value coal gangue according to claim 11, characterized in that: When the calorific value content of coal gangue is 400-700 kcal / kg, the flue gas outlet of the belt type firing equipment is connected with the gas inlet three of the heat exchanger; when the calorific value content of coal gangue is greater than or equal to 700 kcal / kg, the flue gas outlet of the belt type firing equipment is connected with the gas inlet three of the heat exchanger and the inlet of the waste heat power generation system respectively; and the gas outlet three of the heat exchanger is connected with the gas inlet of the flue gas treatment system.

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