Coal gangue comprehensive utilization system and method
By using fluidized bed roasting technology to co-process solid wastes such as coal gangue and phosphogypsum, the problem of low resource utilization efficiency in existing technologies has been solved, enabling the efficient production of porous soil matrix and soil amendment products, which is suitable for large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INSTITUTE OF PROCESS ENGINEERING CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-19
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are insufficient for the efficient co-processing of various solid wastes such as coal gangue and phosphogypsum, resulting in low resource utilization efficiency of coal gangue and failure to effectively regulate pore structure and remove harmful substances, thus affecting soil improvement effects.
By employing a fluidized bed roasting process, coal gangue, biomass, phosphogypsum, and other materials are synergistically processed through controlled roasting temperature and time to form a porous soil matrix, passivate heavy metal ions, adjust pH value, and rationally regulate pore distribution to produce a variety of soil amendment products.
It achieves efficient and environmentally friendly co-processing of multiple solid wastes, producing porous soil matrix and soil improvement products suitable for large-scale production, and improving the resource utilization efficiency of coal gangue.
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Figure CN122057761A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid waste resource utilization technology, and in particular relates to a comprehensive utilization system and method for various solid wastes such as coal gangue and phosphogypsum. Background Technology
[0002] Coal gangue is a solid waste generated during coal mining and washing. It is a dark gray rock with a low carbon content and harder than coal, which is associated with coal seams during coal formation and accounts for about 10-20% of raw coal production. The long-term accumulation of coal gangue not only wastes a large amount of valuable land resources, but also damages the ecological environment, groundwater quality, and landscape of the mining area.
[0003] Open-pit coal and ore mines suffer from a lack of soil, hindering vegetation growth and increasing the risk of geological disasters and soil erosion. Furthermore, human and natural factors have led to ecological degradation and increasingly severe desertification. Currently, the restoration of mining areas and sandy soils typically requires either excavated soil for covering or imported soil for soil improvement followed by planting of trees, shrubs, and grasses. In ecologically fragile areas, the scarcity of soil resources necessitates the extraction of soil from other locations. This not only causes secondary damage to the ecological environment but also results in high restoration costs due to the extraction, loading, unloading, and transportation of the soil. Moreover, these imported soils and gravel often require a process of improvement and acclimatization to adapt to the local soil.
[0004] Coal gangue contains a variety of minerals, including carbon, sulfides, organic matter, illite, chlorite, muscovite, feldspar, pyrite, siderite, hematite, and calcite. Kaolin and quartz comprise over 50% of its composition, and it contains abundant trace elements essential for crop growth, such as Cu, Zn, K, and Ca. Heavy metals harmful to crops, such as Cd, Hg, Cr, and Pb, are present at levels below the standards for agricultural land use. Furthermore, coal gangue originates from coal-bearing strata and shares similar origin, composition, and properties with local rock and soil layers. Therefore, using coal gangue for ecological restoration of mining areas and surrounding soils can avoid the problems associated with incompatible imported sand and soil requiring lengthy cultivation and improvement periods, while also achieving efficient resource utilization of coal gangue.
[0005] Chinese patent CN109438116B discloses a method for preparing a soil conditioner using coal gangue and wood ash. The method involves first mechanically grinding and ultra-finely activating the coal gangue in a steam mill to obtain coal gangue with a particle size of 2–10 μm. Wood ash (potassium content 10–15%) is then added and dehydrated and ground to 60–200 mesh. The mixture is then calcined at 600–900℃ for 0.5–2 hours to obtain a silicon-potassium fertilizer. This method uses a relatively small amount of coal gangue as an additive, and the calcination process to obtain ultra-fine particles from the mechanical grinding and ultra-fine activation of the coal gangue is difficult, making large-scale production challenging.
[0006] Chinese patent application CN115108869A discloses a method and product for producing an organic-inorganic compound soil conditioner using coal gangue. The method involves crushing and sieving the coal gangue to obtain coal gangue powder; leaching the coal gangue powder with an alkaline solution, filtering the slurry to obtain a solution containing humic acid salts; mixing the filter residue with carbonate and sulfate additives; drying, calcining, cooling, and crushing the mixture to obtain a mineral element soil conditioner intermediate; mixing the intermediate, the humic acid salt solution, and compounds containing zinc, selenium, and boron; stirring, drying, and granulating; and drying the granules again to obtain an organic-inorganic compound soil conditioner product for improving acidic soils, replenishing soil minerals and organic matter, and preventing soil compaction and pests / diseases. Because the humic acid content in coal gangue is extremely low (around 0.1-3%), this method uses alkaline solution to leach coal gangue to obtain humic acid, which is then mixed with roasted coal gangue, increasing the complexity of the treatment process. At the same time, the organic-inorganic compound soil conditioner has a high alkali content, resulting in a low consumption of coal gangue.
[0007] Chinese patent application CN109929561A discloses a formula and preparation method for an alkaline soil conditioner made from coal gangue. This method involves high calcination temperatures and long calcination times, without regulating the pore structure, and the conditioner is alkaline and cannot be directly added to the soil. Chinese patent application CN113896578A discloses an organic fertilizer made from coal gangue and its preparation method, while Chinese patent application CN115784808A discloses a method for making a soil conditioner from coal gangue. Neither of these methods alters the dense structure of the coal gangue, nor removes organic pollutants and heavy metals, resulting in a poor pore structure. Chinese patent application CN111117629A discloses a method for preparing a soil conditioner from coal gangue. This method produces a molded foamed body, which is cured at 20–70℃ for 12–65 hours; foaming agents such as aluminum powder, hydrogen peroxide, and baking soda are added. The preparation time for amendments is long, and foaming agents easily lead to the amendments being alkaline. Directly adding coal gangue as filler also suffers from drawbacks: the dense structure of the coal gangue remains unchanged, organic pollutants and heavy metals are not treated, and the poor pore structure of the coal gangue differs significantly from that of soil, making it unsuitable for large-scale use as soil. Chinese patent CN113441533B discloses a method for accelerating waste rock to soil using coal gangue; Chinese patent application CN116140335A discloses a method for enhancing the weathering of coal gangue to soil using medium-low temperature waste heat. Both methods involve complex pile construction methods and structures, making it difficult to control biomass combustion and effectively regulate the product's pore structure. Chinese patent CN116351864A discloses a method for grading and classifying coal gangue and a method for ecological restoration of all coal gangue based on grading and classifying coal gangue. However, this method does not effectively regulate the product's pore structure, thus preventing its direct use as substrate soil.
[0008] Phosphogypsum is an industrial waste residue discharged during the wet process of phosphoric acid production in the phosphate fertilizer industry. Approximately 4.5-5.5 tons of phosphogypsum are produced for every ton of phosphoric acid produced. Phosphogypsum is an important recycled gypsum resource, its main component being calcium sulfate dihydrate. It also contains phosphorus impurities, fluorine impurities, organic impurities, and metal salts. The calcium, sulfur, phosphorus, and metal salts provide nutrients for plant growth, and the low pH of phosphogypsum can also improve soil pH.
[0009] In summary, coal gangue contains a certain amount of carbon, sulfur, and organic pollutants. Long-term stockpiling can lead to spontaneous combustion, polluting water, air, and soil, making it unsuitable for direct soil improvement. It is necessary to use coal gangue as the main raw material to remove excessive carbon and organic pollutants, and to adjust its pore size distribution and porosity to meet the soil's needs for aeration, water retention, and fertilizer retention. Current methods for converting coal gangue into soil involve extensive composting or crushing and screening, neglecting the removal of harmful substances and pore structure control. Therefore, the water retention, fertilizer retention, and aeration effects of the soil prepared from coal gangue are difficult to guarantee. Phosphogypsum can provide nutrients for plant growth, and its low pH value can also improve soil pH. Distillery lees, medicinal herb residues, biomass, fungal substances, phosphogypsum, urban sludge, and river and lake silt all contain organic and inorganic nutrients necessary for plant growth. Co-processing them with roasted coal gangue can passivate harmful heavy metals, achieving the effect of co-processing solid waste. Therefore, researching and developing a system and method for the comprehensive utilization of multiple solid wastes such as coal gangue and phosphogypsum, which can synergistically treat multiple solid wastes and produce multiple products, has good application prospects. Summary of the Invention
[0010] In view of the problems existing in the prior art, the purpose of this invention is to provide a comprehensive utilization system and method for coal gangue. The method provided by this invention has the characteristics of simple process, environmental friendliness, high production efficiency, high heat utilization rate, applicability to large-scale production, and co-processing of multiple solid wastes.
[0011] To achieve the above objectives, the present invention adopts the following technical solution:
[0012] A comprehensive utilization system for coal gangue, the system comprising a feeding process, a roasting process, a heat recovery process, and a product process;
[0013] The feeding process includes a feeding device and a preheater;
[0014] The roasting process includes a fluidized bed roasting furnace, a hot air furnace, an air preheater, and a fluidized bed cooler;
[0015] The heat recovery process includes a waste heat recovery device, a dust collector, and an induced draft fan;
[0016] The product process includes a storage silo, a metering device, a mixing silo, and a finished product silo;
[0017] The discharge port of the feeding device is connected to the inlet of the preheater, and the discharge port of the preheater is connected to the inlet of the fluidized bed roasting furnace; the flue gas outlet of the fluidized bed roasting furnace is connected to the flue gas inlet of the waste heat recovery device, and the solid outlet of the waste heat recovery device is connected to the inlet of the fluidized bed cooler; the flue gas outlet of the waste heat recovery device is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the gas inlet of the chimney.
[0018] The solid outlet of the dust collector is connected to the feed inlet of the fluidized bed cooler; the solid outlet of the fluidized bed roasting furnace is connected to the feed inlet of the air preheater; the solid outlet of the air preheater is connected to the feed inlet of the fluidized bed cooler; the gas outlet of the air preheater is connected to the gas inlet of the preheater; the gas outlet of the preheater is connected to the gas inlet of the dust collector; and the flue gas outlet of the hot air furnace is connected to the gas inlet of the fluidized bed roasting furnace.
[0019] The solid outlet of the fluidized bed cooler is connected to the inlet of the storage silo, the outlet of the storage silo is connected to the inlet of the metering device, the outlet of the metering device is connected to the inlet of the mixing silo, and the outlet of the mixing silo is connected to the inlet of the finished product silo.
[0020] This invention further provides a method for comprehensive utilization of coal gangue based on the above system, the method comprising:
[0021] (1) Coal gangue particles or coal gangue particles and additives are fed into the fluidized bed roasting furnace through the feeding process;
[0022] (2) The solid is roasted at 500℃~900℃ for 5~60min in a fluidized bed roasting furnace; after roasting, the solid is heated by exchanging heat with air in an air preheater to obtain roasted material which is then sent to the product process.
[0023] (3) In the product process, the roasted material is mixed with additives to form coal gangue-based composite ecological soil, microbial fertilizer, compound fertilizer or mineral fertilizer; or, the roasted material is directly used as activated coal gangue material.
[0024] (4) The hot flue gas in the fluidized bed roasting furnace described in step (2) enters the heat recovery process to recover heat. After the heat is recovered, the flue gas is purified and dust removed by a dust collector and then discharged in compliance with standards.
[0025] This invention can co-process various solid wastes such as coal gangue, biomass, phosphogypsum, and oil sludge to produce coal gangue-based composite ecological soil, microbial fertilizer, compound fertilizer, and mineral fertilizer, achieving the goal of co-processing multiple solid wastes and producing multiple products with a single device. It can also separately calcine coal gangue to produce activated coal gangue materials, which can be used for limestone calcination clay cement (LC3), silicate cement, and the preparation of aluminates, molecular sieves, adsorbents, and silica.
[0026] In this invention, the feeding process may include a crushing device, a screening device, a feeding device, and a preheater connected in sequence. Large pieces of coal gangue are crushed and screened into particles of 0.01–1 mm in the feeding process.
[0027] When the feeding process involves flammable additives, the hot air furnace may be discontinued.
[0028] The additive is one or a combination of at least two of the following: distiller's grains, Chinese medicinal residues, straw, biomass compressed pellet fuel, lignocellulose, oil sludge, and phosphogypsum.
[0029] The crushing device can be one or more of the following: jaw crusher, cone crusher, gyratory crusher, hammer crusher, roller crusher, impact crusher, cone crusher, toothed pulverizer, hammer mill, knife mill, turbine mill, pressure mill, milling mill, air jet mill, ball mill, mortar mill, etc.
[0030] The screening device is one or more of the following: fixed screen, rotating screen, vibrating screen, air classifier, etc.
[0031] The preheater consists of one or more cyclone preheaters connected in parallel or in series, and is mainly used to preheat solid materials; the temperature of the material after preheating by the preheater is below 310°C.
[0032] The fluidized bed roasting furnace can be one or a combination of a single-chamber fluidized bed roasting furnace, a multi-chamber fluidized bed roasting furnace, and a decoupled combustion furnace. When the fluidized bed roasting furnace is a decoupled combustion furnace, it can be used in conjunction with a waste heat boiler. The fluidized bed roasting furnace can be equipped with supplementary combustion facilities.
[0033] The hot air furnace can be a direct-type high-purity hot air furnace, an indirect-type hot air furnace, or a chain-grate energy-saving hot air furnace. The hot air temperature is 400-1100℃. Preferably, the hot air temperature is 500-1100℃.
[0034] The air preheater consists of one or more cyclone preheaters connected in series or in parallel.
[0035] The dust collector can be one or more of the following: cyclone separator, metal dust collector, and bag filter.
[0036] The fluidized bed cooler can be a single-chamber fluidized bed cooler or a multi-chamber fluidized bed cooler. Preferably, a water or gas cooling heat exchange tube can be added inside the fluidized bed cooler.
[0037] Specifically, the roasting process consists of a fluidized bed roasting furnace, a hot air furnace, a two-stage air preheater, and a fluidized bed cooler. The gas from the fluidized bed roasting furnace enters the heat recovery process. The solid outlet of the fluidized bed roasting furnace is connected to the inlet of the first-stage air preheater, and the solid outlet of the first-stage air preheater is connected to the inlet of the second-stage air preheater; the gas outlet of the second-stage air preheater is connected to the gas inlet of the first-stage air preheater. The gas outlet of the first-stage air preheater is connected to the gas inlet of the preheater, and the gas outlet of the preheater is connected to the gas inlet of the purification and dust removal system. The flue gas outlet of the hot air furnace is connected to the gas inlet of the fluidized bed roasting furnace. The solid outlet of the second-stage air preheater is connected to the inlet of the fluidized bed cooler, and the solid outlet of the fluidized bed cooler is connected to the product process inlet. The gas outlet of the fluidized bed cooler is connected to the gas inlet of the second-stage air preheater. The air in the heat exchange tubes of the fluidized bed cooler is connected to the air inlet of the hot air furnace.
[0038] Preferably, the gas from the fluidized bed roasting furnace enters the heat recovery process. The solid outlet of the fluidized bed roasting furnace is connected to the inlet of the primary air preheater, and the solid outlet of the primary air preheater is connected to the inlet of the secondary air preheater. The gas outlet of the secondary air preheater is connected to the gas inlet of the primary air preheater. The gas outlet of the primary air preheater is connected to the gas inlet of the preheater, and the gas outlet of the preheater is connected to the gas inlet of the purification dust collector. The solid outlet of the secondary air preheater is connected to the inlet of the fluidized bed cooler, and the solid outlet of the fluidized bed cooler is connected to the product process inlet. The gas outlet of the fluidized bed cooler is connected to the gas inlet of the secondary air preheater. The air in the heat exchange tubes of the fluidized bed cooler is connected to the gas inlet of the fluidized bed roasting furnace.
[0039] Specifically, the heat recovery process consists of a waste heat boiler, a cyclone separator, a dust collector, an induced draft fan, and a chimney. The flue gas outlet of the fluidized bed roasting furnace is connected to the gas inlet of the cyclone separator, the gas outlet of the cyclone separator is connected to the flue gas inlet of the waste heat boiler, and the solids outlet of the cyclone separator is connected to the discharge port of the fluidized bed roasting furnace. The flue gas outlet of the waste heat boiler is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the gas inlet of the chimney. The solids outlet of the dust collector is connected to the feed inlet of the fluidized bed cooler.
[0040] In the heat recovery process, the cyclone separator can be a single stage or multiple stages connected in series or parallel, mainly to achieve gas-solid separation of materials.
[0041] Specifically, the product process comprises a storage silo, a metering device, a mixing silo, and a finished product silo. The outlet of the fluidized bed cooler is connected to the inlet of the storage silo, the outlet of the storage silo is connected to the inlet of the metering device, the outlet of the metering device is connected to the inlet of the mixing silo, and the outlet of the mixing silo is connected to the inlet of the finished product silo. Preferably, when producing activated coal gangue material, the outlet of the fluidized bed cooler is connected to the inlet of the storage silo.
[0042] The configuration of the metering device is matched to the type and quantity of the additives to be added. The additives can be one or more combinations of biomass, microorganisms, phosphogypsum, urban sludge, river and lake silt, organic fertilizers, and inorganic fertilizers. Specifically, the additives can be sugarcane residue, nitrogen-fixing bacteria, wheat straw, Bacillus mucilaginosus, Bacillus polymyxa, phosphogypsum, etc.
[0043] This invention employs a fluidized bed roasting method to regulate the ordered and controllable oxidation of carbon in coal gangue through roasting temperature and time, as well as the decomposition of minerals such as kaolinite, metakaolinite, and calcium carbonate to form a porous structure. By controlling the carbon oxidation rate and the mineral decomposition rate, the pore distribution of coal gangue particles is rationally regulated. The roasted material, as a porous soil matrix, has a total porosity >50%, with 25-35% water-holding pores (0.0001-0.03 mm) and 15-30% aeration pores (>0.03 mm), providing a porous structure for water and fertilizer retention. After roasting, the coal gangue can passivate heavy metal ions and regulate the soil pH. This invention can efficiently and rapidly remove carbon from coal gangue, decompose kaolinite components in coal gangue, regulate the pore distribution of coal gangue particles, and provide a porous structure for water and fertilizer retention or activate coal gangue.
[0044] This invention provides a method for the comprehensive utilization of coal gangue to prepare coal gangue-based composite ecological soil, microbial fertilizer, compound fertilizer, and mineral fertilizer. These methods can be used for ecological restoration in mining areas and improvement of desertified soil.
[0045] This invention provides a method for continuous and efficient activation of coal gangue, producing activated coal gangue material with uniform and high activity. It can be used in limestone calcination clay cement (LC3), silicate cement, and the preparation of aluminates, molecular sieves, adsorbents, and silica.
[0046] Compared with the prior art, the present invention has at least the following beneficial effects:
[0047] (1) This invention can achieve the synergistic treatment of coal gangue, phosphogypsum, biomass, sludge, etc., and provide an effective solution for the comprehensive treatment of solid waste.
[0048] (2) This invention can remove excessive carbon and organic matter from coal gangue that are prone to spontaneous combustion, while retaining elements such as sulfur, calcium and potassium that are beneficial to plant growth. At the same time, it can rationally regulate the pore distribution of coal gangue particles, with a total porosity of >50% for porous soil matrix, 25-35% for water-holding pores of 0.0001-0.03mm, and 15-30% for aeration pores of >0.03mm, thus providing a pore structure for water and fertilizer retention.
[0049] (3) The roasted coal gangue of the present invention can passivate heavy metal ions and adjust the soil pH value.
[0050] (4) The present invention can produce a variety of products by roasting with one set of equipment, such as activated coal gangue materials, porous coal gangue materials, coal gangue-based composite ecological soil, microbial fertilizer, compound fertilizer, mineral fertilizer, etc. Attached Figure Description
[0051] Figure 1 This is a schematic diagram of the layout of the integrated utilization system of the present invention.
[0052] Figure 2 This is another schematic diagram of the integrated utilization system of the present invention. Detailed Implementation
[0053] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0054] Example 1
[0055] like Figure 1 As shown, a comprehensive utilization system for coal gangue includes a feeding process, a roasting process, a heat recovery process, and a product process.
[0056] The feeding process includes a feeding device and a preheater;
[0057] The roasting process includes a fluidized bed roasting furnace, a hot air furnace, a primary air preheater, a secondary air preheater, and a fluidized bed cooler;
[0058] The heat recovery process includes a waste heat recovery device, a dust collector, an induced draft fan, and a chimney;
[0059] The product process includes a storage silo, a metering device, a mixing silo, and a finished product silo;
[0060] The discharge port of the feeding device is connected to the inlet of the preheater, and the discharge port of the preheater is connected to the inlet of the fluidized bed roasting furnace; the flue gas outlet of the fluidized bed roasting furnace is connected to the flue gas inlet of the waste heat recovery device, and the solid outlet of the waste heat recovery device is connected to the inlet of the fluidized bed cooler; the flue gas outlet of the waste heat recovery device is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the gas inlet of the chimney; the solid outlet of the dust collector is connected to the inlet of the fluidized bed cooler.
[0061] The solid outlet of the fluidized bed roasting furnace is connected to the inlet of the primary air preheater; the solid outlet of the primary air preheater is connected to the inlet of the secondary air preheater; the gas outlet of the secondary air preheater is connected to the gas inlet of the primary air preheater; the gas outlet of the primary air preheater is connected to the gas inlet of the preheater; the gas outlet of the preheater is connected to the gas inlet of the purification dust collector; the flue gas outlet of the hot air stove is connected to the gas inlet of the fluidized bed roasting furnace; the solid outlet of the secondary air preheater is connected to the inlet of the fluidized bed cooler.
[0062] The solid outlet of the fluidized bed cooler is connected to the inlet of the storage silo, the outlet of the storage silo is connected to the inlet of the metering device, the outlet of the metering device is connected to the inlet of the mixing silo, and the outlet of the mixing silo is connected to the inlet of the finished product silo.
[0063] The fluidized bed roasting furnace is a single-chamber fluidized bed roasting furnace or a multi-chamber fluidized bed roasting furnace.
[0064] The hot air furnace can be a direct-type high-purity hot air furnace, an indirect-type hot air furnace, or a chain-grate energy-saving hot air furnace. The hot air temperature is 400-1100℃.
[0065] The fluidized bed cooler can be a single-chamber fluidized bed cooler or a multi-chamber fluidized bed cooler.
[0066] Example 2
[0067] like Figure 2 As shown, unlike Example 1, this example does not use a hot blast stove; the waste heat recovery device includes a waste heat boiler and a cyclone separator. The roasting process includes a fluidized bed roasting furnace, a primary air preheater, a secondary air preheater, and a fluidized bed cooler. In this case, the flue gas outlet of the fluidized bed roasting furnace is connected to the gas inlet of the cyclone separator, the gas outlet of the cyclone separator is connected to the flue gas inlet of the waste heat boiler, and the solids outlet of the cyclone separator is connected to the discharge port of the fluidized bed roasting furnace. The flue gas outlet of the waste heat boiler is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the gas inlet of the chimney. The solids outlets of the waste heat boiler and the dust collector are connected to the feed inlet of the fluidized bed cooler. A supplementary combustion facility is added to the fluidized bed roasting furnace.
[0068] In this embodiment, the dust collector is a bag filter. The fluidized bed roasting furnace is a decoupled combustion furnace.
[0069] Example 3
[0070] Based on the system described in Example 1, this example provides a method for preparing nitrogen-fixing bacterial fertilizer through comprehensive utilization of coal gangue, the method comprising the following steps:
[0071] (1) Large coal gangue is crushed into 0.01-1mm particles and fed into the fluidized bed roaster together with biomass compressed pellet fuel through the feeding process;
[0072] (2) The solid is roasted at 750°C for 20 minutes in a fluidized bed roasting furnace. After roasting, the solid passes through a two-stage air preheater and a fluidized bed cooler to exchange heat with the air and recover heat. The resulting porous soil matrix (roasting material) has a total porosity of 54%, with 30% of the water-holding pores being 0.0001 to 0.03 mm and 23% of the air-permeable pores being >0.03 mm. It is then sent to the product process.
[0073] (3) Add 30% sugarcane residue and 0.3% nitrogen-fixing bacteria to make nitrogen-fixing bacteria fertilizer;
[0074] (4) The hot flue gas in the fluidized bed roasting furnace described in step (2) enters the heat recovery process after being removed by cyclone dust removal. The flue gas is then further removed by bag dust removal before entering the chimney for emission in compliance with standards.
[0075] Example 4
[0076] Based on the system described in Example 2, this example provides a method for preparing coal gangue-based composite ecological soil through comprehensive utilization of coal gangue, the method comprising the following steps:
[0077] (1) Large coal gangue is crushed into 0.03-1mm particles and fed into the fluidized bed roasting furnace together with dried distiller's grains through the feeding process;
[0078] (2) The solid is roasted at 900°C for 5 minutes in a fluidized bed roasting furnace. After roasting, the solid passes through a two-stage air preheater and a fluidized bed cooler to exchange heat with the air and recover heat. The resulting porous soil matrix (roasting material) has a total porosity of 56%, with 26% of the water-holding pores being 0.0001 to 0.03 mm and 24% of the air-permeable pores being >0.03 mm. It is then sent to the product process.
[0079] (3) Add 45% wheat straw, 0.2% Bacillus mucilaginosus and 0.4% Bacillus polymyxa to make coal gangue-based composite ecological soil;
[0080] (4) The hot flue gas in the fluidized bed roasting furnace described in step (2) enters the heat recovery process after being removed by cyclone dust removal. The flue gas is then further removed by bag dust removal before entering the chimney for emission in compliance with standards.
[0081] Example 5
[0082] Based on the system described in Example 1, this example provides a method for preparing coal gangue-based composite ecological soil through comprehensive utilization of coal gangue, the method comprising the following steps:
[0083] (1) Large pieces of coal gangue are crushed into 0.01-1mm particles and fed into the fluidized bed roasting furnace together with the Chinese medicine residue.
[0084] (2) The solid is roasted at 500°C for 60 minutes in a fluidized bed roasting furnace. After roasting, the solid passes through a two-stage air preheater and a fluidized bed cooler to exchange heat with the air and recover heat. The resulting activated coal gangue material is then sent to the product process.
[0085] (3) Add 12% phosphogypsum and 8% wheat straw to make coal gangue-based composite ecological soil;
[0086] (4) The hot flue gas in the fluidized bed roasting furnace described in step (2) enters the heat recovery process after being removed by cyclone dust removal. The flue gas is then further removed by bag dust removal before entering the chimney for emission in compliance with standards.
[0087] The upper and lower limits of the process parameters (such as temperature, time, etc.) and the range values of the present invention can all achieve the method, and examples are not listed here.
[0088] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.
[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A comprehensive utilization system for coal gangue, characterized in that, The system includes a feeding process, a roasting process, a heat recovery process, and a product process; The feeding process includes a feeding device and a preheater; The roasting process includes a fluidized bed roasting furnace, a hot air furnace, an air preheater, and a fluidized bed cooler; The heat recovery process includes a waste heat recovery device, a dust collector, and an induced draft fan; The product process includes a storage silo, a metering device, a mixing silo, and a finished product silo; The discharge port of the feeding device is connected to the inlet of the preheater, and the discharge port of the preheater is connected to the inlet of the fluidized bed roasting furnace; the flue gas outlet of the fluidized bed roasting furnace is connected to the flue gas inlet of the waste heat recovery device, and the solid outlet of the waste heat recovery device is connected to the inlet of the fluidized bed cooler; the flue gas outlet of the waste heat recovery device is connected to the gas inlet of the dust collector, the gas outlet of the dust collector is connected to the inlet of the induced draft fan, and the outlet of the induced draft fan is connected to the gas inlet of the chimney. The solid outlet of the dust collector is connected to the feed inlet of the fluidized bed cooler; the solid outlet of the fluidized bed roasting furnace is connected to the feed inlet of the air preheater; the solid outlet of the air preheater is connected to the feed inlet of the fluidized bed cooler; the gas outlet of the air preheater is connected to the inlet of the preheater; the gas outlet of the preheater is connected to the gas inlet of the dust collector; and the flue gas outlet of the hot air furnace is connected to the gas inlet of the fluidized bed roasting furnace. The solid outlet of the fluidized bed cooler is connected to the inlet of the storage silo, the outlet of the storage silo is connected to the inlet of the metering device, the outlet of the metering device is connected to the inlet of the mixing silo, and the outlet of the mixing silo is connected to the inlet of the finished product silo.
2. The coal gangue comprehensive utilization system according to claim 1, characterized in that, The air preheater includes multiple stages of air preheaters connected in series. The gas outlet of the subsequent stage air preheater is connected to the gas inlet of the preceding stage air preheater, and the gas outlet of the first stage air preheater is connected to the gas inlet of the preheater. The gas inlet of the last stage in the multi-stage air preheater is connected to the gas outlet of the fluidized bed cooler.
3. The coal gangue comprehensive utilization system according to claim 1, characterized in that, The waste heat recovery device includes a waste heat boiler and a cyclone separator; The flue gas outlet of the fluidized bed roaster is connected to the inlet of the cyclone separator, the gas outlet of the cyclone separator is connected to the flue gas inlet of the waste heat boiler, and the solid outlet of the cyclone separator is connected to the solid discharge port of the fluidized bed roaster.
4. The coal gangue comprehensive utilization system according to claim 1, characterized in that, The fluidized bed roasting furnace is one or a combination of at least two of the following: a single-chamber fluidized bed roasting furnace, a multi-chamber fluidized bed roasting furnace, and a decoupled combustion furnace; when the fluidized bed roasting furnace is a decoupled combustion furnace, it can be used in conjunction with a waste heat boiler; furthermore, the fluidized bed roasting furnace can be equipped with supplementary combustion facilities.
5. The coal gangue comprehensive utilization system according to claim 1, characterized in that, The fluidized bed cooler is a single-chamber fluidized bed cooler or a multi-chamber fluidized bed cooler. Preferably, the fluidized bed cooler contains air heat exchange tubes.
6. The coal gangue comprehensive utilization system according to claim 1, characterized in that, The hot air temperature of the hot air furnace is 400-1100℃; in the feeding process, the temperature of the material after preheating by the preheater is lower than 310℃.
7. A method for comprehensive utilization of coal gangue based on the system according to any one of claims 1-6, the method comprising: (1) Coal gangue particles or coal gangue particles and additives enter the fluidized bed roasting furnace from the feeding process; (2) The solid is roasted at 500℃~900℃ for 5~60min in a fluidized bed roasting furnace; after roasting, the solid is heated by exchanging heat with air in an air preheater to obtain roasted material which is then sent to the product process. (3) In the product process, the roasted material is mixed with additives to form coal gangue-based composite ecological soil, microbial fertilizer, compound fertilizer or mineral fertilizer; or, the roasted material is directly used as activated coal gangue material. (4) The hot flue gas in the fluidized bed roasting furnace described in step (2) enters the heat recovery process to recover heat. After the heat is recovered, the flue gas is purified and dust removed by a dust collector and then discharged in compliance with standards.
8. The method for comprehensive utilization of coal gangue according to claim 7, characterized in that, The coal gangue particles are obtained by crushing large pieces of coal gangue, with a particle size of 0.01-1mm.
9. The method for comprehensive utilization of coal gangue according to claim 7, characterized in that, The additive is one or a combination of at least two of the following: distiller's grains, Chinese medicinal residues, straw, biomass compressed pellet fuel, lignocellulose, oil sludge, and phosphogypsum.
10. The method for comprehensive utilization of coal gangue according to claim 7, characterized in that, The additive is one or a combination of at least two of the following: biomass, fungal substances, phosphogypsum, urban sludge, river and lake silt, organic fertilizer, and inorganic fertilizer.