Method and equipment for producing black soil and humus fertilizer by coal gangue decarburization

Abstract

A method and equipment for preparing black soil and humus fertilizer from coal gangue by decarburization, the method mainly comprises the following steps: (1) preparation of suspension separation medium; (2) coal gangue preparation: according to the specific characteristics of coal gangue in different mining areas under different geological conditions, the following preliminary treatment is carried out respectively; 1) for shale mining area coal gangue, coal gangue particle with low sulfide content, little stone-coal / coal-stone and hard block material, particle size ≤ 150 mm is directly selected; for stone-coal / coal-stone or large block gangue, the coal gangue particle with particle size ≤ 150 mm is pre-pulverized and prepared; 2) for hard block material and stone-coal / coal-stone, and coal gangue containing sulfide, the coal gangue particle with particle size ≤ 100 mm is selectively pulverized and separated and prepared; (3) decarburization to prepare black soil and humus fertilizer. The application also includes equipment for implementing the method. By using the application, large-scale and effective utilization of coal gangue can be realized, and ecological and safe black soil and humus fertilizer can be efficiently prepared.

Description

Technical Field

[0001] This invention relates to a method and equipment for the resource utilization of solid waste, and more particularly to a method and equipment for decarbonizing coal gangue to produce virgin black soil and humic fertilizer. Background Technology

[0002] Coal gangue is a major solid waste product of the coal industry. It is mainly composed of aluminosilicate minerals such as shale, carbonate rock, sandstone, and residual carbon. The specific composition varies depending on the geological and mineral conditions of the mining area, with shale gangue accounting for more than 80%.

[0003] It is well known that coal is formed from the slow reaction of plants under high temperature and pressure geological conditions. However, what has long been overlooked is that during the process of plants forming coal through thermal pressure, most of the humus is absorbed by aluminosilicate minerals such as shale, forming black shale. Most of the free heavy metals and fluorine in these minerals are adsorbed by the natural adsorption of carbon into pure coal blocks, or exist as independent mineral crystals such as arsenopyrite and phosphate rock. Our long-term tracking and sampling analysis shows that, on average, about 81.33% of the humus in shale mining areas is present in... In black shale, humus accounts for an average of about 18.67% in pure coal blocks. Harmful heavy metals such as lead, mercury, arsenic, and chromium, as well as fluorine, are mainly adsorbed in pure coal or exist as independent sulfide ores. The total heavy metal content in black shale averages only 14.31%, with approximately 85.7% adsorbed in coal blocks or existing as sulfide mineral crystals. The total heavy metal content of most shale-type coal gangue is within safe limits. In fact, shale-type gangue containing a large amount of humus generally has very low heavy metal content and is safe. Objectively, shale-type gangue is easily weathered and expands when exposed to water. It contains abundant organic matter (mostly 15-36%) and various trace elements necessary for plant growth, such as nitrogen, phosphorus, potassium, zinc, copper, selenium, and germanium. Its heavy metal content is safe, and after decarbonization and impurity removal, it is classified as "clean" waste residue, representing a potentially high-quality, naturally occurring "primary black soil" formed underground. Obviously, the heavy metals and fluorine elements that may be contained in coal gangue are concentrated in the residual carbon (coal particles) and hard sulfide mineral blocks. To obtain this kind of "primary black soil" from coal gangue, decarbonization treatment is required, but the organic matter (humus) content in shale gangue cannot be reduced, as this would damage the structure of natural clay minerals.

[0004] Existing methods for decarbonizing coal gangue mostly employ high-temperature hot air decarbonization, roasting decarbonization, or flotation. These high-temperature hot air decarbonization or roasting decarbonization technologies have high energy consumption, and the high-temperature or hot air treatment inevitably damages the structure of humus and natural clay minerals, affecting soil organic matter fertility.

[0005] For example, CN201911146651.0 discloses a coal gangue decarbonization device, including an air inlet pipe, a material spreading device, a decarbonization box, a decarbonization cylinder, and a guide pipe; the decarbonization box includes a shell, a material guiding device, and a material guiding hole; the material guiding device has a stepped structure and is fixed inside the shell. By setting the material guiding device to a stepped structure, the cross-sectional area through which the high-temperature gas flows into the decarbonization box gradually decreases, causing the high-temperature gas to exert different forces on the coal gangue located in different areas. After contacting the coal gangue, the high-temperature gas decarbonizes it, and the decarbonized coal gangue becomes denser. The temperature decreases, and under the action of high-temperature gas wind, it moves from the higher end of the stepped structure to the lower end. Although the equipment uses variable cross-sectional area to adjust the wind speed to enhance the decarbonization effect, such decarbonization is not only energy-intensive, but also has a very limited processing capacity. It is more than enough to produce ceramsite that is disproportionate to the volume of coal gangue. However, if it is used to produce virgin black soil in large quantities, it will have irreversible adverse consequences, namely, a significant reduction in the humus content in the virgin black soil and damage to the natural clay mineral structure, which is not conducive to the quality assurance of the produced virgin black soil and the resource utilization of large quantities of solid waste coal gangue.

[0006] Flotation decarbonization has several drawbacks: firstly, it involves large investments, high energy consumption, and secondary pollution; secondly, it easily transfers heavy metals and fluorine elements enriched in coal particles to argillaceous shale, and usually mixes crushed heavy metal sulfide minerals into the argillaceous shale; and thirdly, flotation reagents introduce large amounts of alkali and organic pollutants, which are extremely difficult to remove, causing the argillaceous shale after flotation decarbonization to be objectively transformed into sludge, which is no longer suitable for soil improvement or as agricultural fertilizer. Even in improved advanced flotation technologies, such as the extraction of alumina from high-alumina coal gangue, some researchers use flotation decarbonization processes to perform multi-stage flotation on the carbon-containing coal gangue. This involves multi-stage crushing, screening, and grinding to achieve a particle size of 45-75μm, followed by multi-stage flotation to separate the high-alumina gangue slag and carbon. This decarbonization technology is relatively more suitable for manufacturing high-value-added alumina, but it poses significant problems for manufacturing large quantities of low-cost, lightly crushed (below 25mm) primary black soil. Not only is the equipment investment and energy consumption enormous, but the flotation decarbonization slag is also polluted sludge with high levels of alkali, salt, and organic pollutants, which is detrimental to the production of primary black soil and agricultural fertilizer.

[0007] Secondly, heavy media coal preparation technology is a commonly used technology in raw coal preparation industry. It is a gravity-based coal preparation method that uses a heavy liquid or heavy suspension with a density greater than water and between that of coal and gangue as the separation medium. Depending on the medium used, it can be divided into two main categories: heavy liquid coal preparation and heavy suspension coal preparation. Heavy liquids refer to aqueous solutions of certain inorganic salts and high-density organic solutions, such as ferric chloride, manganese chloride, calcium chloride, barium chloride, trichloroethane, carbon tetrachloride, pentachloroethane, or dibromoethane. Ultimately, these are often not used due to their strong corrosiveness, health hazards, difficulty in recovery, and high cost. Heavy suspensions are two-phase fluids with a certain density, prepared from high-density solid particles, often barite powder, ferrosilicon powder, magnetite powder, water, and thickeners, forming a suspension with a specific density. When raw coal is fed into a separator filled with this suspension, coal with a density less than the suspension floats, while gangue (or middlings) with a density greater than the suspension sinks, achieving separation by density. The most widely used heavy medium coal preparation method in production is heavy suspension coal preparation, commonly known as heavy medium coal preparation. Typical heavy medium coal preparation equipment includes heavy medium hydrocyclones, heavy medium shallow trough separators, and lifting wheel heavy medium separators. Heavy medium hydrocyclones are separators that utilize a centrifugal force field tens or even hundreds of times stronger than gravity. They have strict particle size classification, but their use in producing primary black soil is not only costly but also involves a relatively large investment, making large-scale application difficult. Heavy medium shallow trough separation is based on Archimedes' principle. Raw coal and heavy medium suspension are mixed in the separator. Due to the density difference, under the action of horizontal and upward flow, the less dense floating matter is transported to the overflow weir and discharged, while the denser sediment falls to the bottom of the trough and is scraped to the discharge port by a scraper conveyor. These two types of liquid flow have a significant impact on the separation efficiency. Generally, the stability of a suspension is determined by the upflow velocity, while the lower limit of the feed particle size is determined by the horizontal flow velocity. Heavy medium shallow trough separators typically use 25 mm or 13 mm as the lower limit for particle separation. Some heavy medium shallow trough separators use 6 mm as the lower limit, but for particle sizes below 6 mm, heavy medium shallow trough separators are often insufficient and require the use of heavy medium hydrocyclones, spiral separators, or filter presses. Heavy media separators typically include vertical and inclined wheel types. Coal that has undergone screening is fed into a heavy media suspension tank for separation. The principle is to adjust the density of the suspension, causing fine coal with a density lower than the suspension to float to the surface and be scraped out by the discharge wheel. Gangue and high-ash coal with a density greater than the suspension are scraped out by the gangue discharge scraper and discharged through a chute. This equipment is large and occupies a large area. It also requires grading and separating coal particles, but the separation of small particles is incomplete. While advantageous in coal preparation, it is ineffective in decarbonizing coal gangue and introduces large amounts of soil pollutants.In existing coal heavy media separation processes, a combination of methods is often required. For example, a shallow heavy media tank is used to handle particles of 13mm-150mm, while particles of 1.5mm-13mm are separated using a heavy media hydrocyclone, particles of 0.15mm-1.5mm are separated using a coarse coal slime spiral separator, and fine coal slime below 0.15mm is recovered using a filter press or plate and frame filter press. Such equipment systems for coal separation not only require huge investments in coal preparation equipment but also occupy a large area. They are not suitable for decarbonizing low-calorific-value coal gangue and will introduce large amounts of chloride salts or heavy media (barite powder, ferrosilicon powder, magnetite powder) and toxic and harmful pollutants that are unsuitable for soil optimization.

[0008] In summary, existing coal gangue decarbonization technologies and coal preparation technologies and equipment cannot meet the requirements for producing native black soil and humic fertilizer from coal gangue. As a result, the resource utilization effect of coal gangue, a major solid waste in my country, which relies heavily on coal as an energy source, has been unsatisfactory after decades of development. Even the mainstream technology advocated for coal gangue disposal is still the simple soil covering and planting technology, which involves requisitioning farmland and mountains to build dams and pile up coal gangue, and then covering it with soil and planting vegetation. This is the method commonly adopted by coal mines in recent years under environmental protection requirements. The basic operating model is that coal mines requisition land, usually nearby farmland or mountain gullies, build dams, pile up coal gangue, and usually hire people to push soil to fill the dams at a price of 30 yuan / ton of coal gangue, and then plant vegetation on top. The article "A Pilot Study on Artificial Soil Construction and Greening of Coal Gangue Hills" (see *Safety and Environmental Engineering*, Vol. 30 No. 3 May 2023) fully affirms the successful experience of the Xiangshui Coal Mine in Guizhou Province in requisitioning farmland to build dams and cover coal gangue hills with vegetation. While this method is simple and easy to implement and meets current environmental protection and greening requirements, it does several problems: firstly, it occupies existing farmland; secondly, it wastes a large amount of valuable organic matter and clay resources in the coal gangue, i.e., it wastes a large amount of naturally formed black soil resources underground; and thirdly, it easily causes groundwater and soil pollution.

[0009] Although the technology for the resource utilization and reduction of coal gangue is developing rapidly, due to the diversity and complexity of coal gangue composition, there is currently no simple, effective, and low-cost method or technical equipment for the efficient resource utilization of each component of coal gangue.

[0010] On the other hand, my country's existing land degradation is quite serious, the content of organic humus in the soil is decreasing year by year, the land is gradually becoming barren, and rocky desertification is also quite serious. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method and equipment that requires less equipment investment, occupies less land area, has low operating energy consumption, and can remove residual carbon (coal particles) rich in heavy metals and fluorine from coal gangue on a large scale, and directly produce raw black soil and humic fertilizer free of chloride salts and toxic and harmful substances from coal gangue.

[0012] The technical solution adopted by this invention to solve its technical problem is: a method for decarbonizing coal gangue to produce virgin black soil and humus fertilizer, mainly including the following steps:

[0013] (1) Preparation of suspension separation medium: Based on the requirement that black soil and humic fertilizer must not contain excessive levels of toxic and harmful substances such as chlorine, fluorine, sulfur, alkali (sodium), heavy metals, and organic pollutants, and considering the mineral composition characteristics of coal gangue, a nitrogen-based medium that is non-flammable, non-toxic, odorless, and free of harmful elements such as fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, and organic pollutants is selected, dissolved in water, and prepared to have a density of 1.35–1.7 g / cm³. 3 The solution is used as an environmentally friendly suspension separation medium for decarbonization of coal gangue;

[0014] (2) Coal gangue preparation: Based on the specific characteristics of coal gangue from different mining areas under different geological conditions, the following preliminary treatments are carried out respectively:

[0015] 1) For coal gangue from shale mines, coal gangue with low sulfide content, very little coal / coal-encased stone and hard lumps, and a particle size ≤150mm can be selected directly; coal gangue with coal / coal-encased stone or large lumps can be pre-crushed to a particle size ≤150mm and kept on standby.

[0016] 2) For hard lumps and coal gangue containing sulfides, selectively crush and sort out the hard lumps >100mm as building material raw materials, and the coal gangue granules ≤100mm for later use;

[0017] (3) Decarbonization to produce raw black soil and humus fertilizer:

[0018] 1) Using a suspension and shovel separation device, the environmentally friendly suspension separation medium obtained in step (1) is injected into the U-shaped trough of the suspension and shovel separation device. Coal gangue particles are continuously added into the U-shaped trough of the suspension and shovel separation device from the feed inlet. The coal gangue particles falling into the suspension medium from the feed inlet are immediately subjected to the first-stage suspension and shovel separation, so that most of the coal is separated and suspended in time. The bottom gangue slag is subjected to the second-stage shovel and suspension separation. After the coal gangue particles are suspended and shoveled by the first-stage suspension and shovel separation mechanism and the bottom gangue slag is shoveled and suspended by the second-stage shovel and suspension separation mechanism, the suspended coal is extracted, washed, and dewatered by the coal material filtration device. The waste liquid containing the suspension separation medium and humic mud is recovered to obtain the coal material obtained by decarbonizing coal gangue.

[0019] 2) The gangue slag separated by the secondary flushing suspension separation medium is extracted, washed, and dewatered by the raw black soil filtration device, and the waste liquid containing the suspension separation medium and humic mud is recovered to obtain raw black soil.

[0020] 3) The waste liquid containing the suspended separation medium and humic sludge is sent to the vibration dewatering mechanism of the humic fertilizer filtration device. The wastewater containing the suspended separation medium is collected by the wastewater collection mechanism and sent to the suspended separation medium solution replenishment device. The dewatered humic sludge is collected and discharged from the outlet to obtain humic fertilizer.

[0021] Furthermore, in step (1), the non-flammable, non-toxic, odorless, and free of harmful elements and organic pollutants such as fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, etc., is a mixture of one or more of water-soluble nitrates, such as manganese nitrate / iron / magnesium / calcium / potassium nitrate and amino acid derivatives.

[0022] This invention discloses equipment for decarbonizing coal gangue to produce raw black soil and humic fertilizer. The equipment mainly includes a suspension-flushing separation device, a coal material filtration device, a raw black soil filtration device, a humic fertilizer filtration device, and a suspension separation medium solution replenishment device. The coal material filtration device is located above or to the side of the suspension-flushing separation device and is connected to the U-shaped trough of the suspension-flushing separation device. The raw black soil filtration device is located at the end of the U-shaped trough of the suspension-flushing separation device and is connected to its discharge port. The inlet of the humic fertilizer filtration device is connected to the filtrate outlets of the coal material filtration device and the raw black soil filtration device via pipelines. The circulating wastewater inlet of the suspension medium solution replenishment device is connected to the wastewater outlet of the humic fertilizer filtration device via a pipeline. The heavy medium solution outlet of the suspension separation medium solution replenishment device is connected to the suspension-flushing separation device via a pipeline.

[0023] Furthermore, the aforementioned suspension-flushing separation device mainly includes a U-shaped trough, a single-shaft, double-shaft, or multi-shaft spiral mechanism, a first-stage suspension-flushing separation mechanism, a second-stage flushing-suspension separation mechanism, a filtration mechanism, a circulating pump, a feed inlet, and a discharge outlet. The single-shaft, double-shaft, or multi-shaft spiral mechanism is located at the bottom of the U-shaped trough, and its function is to agitate and propel the settled coal gangue material towards the end. The feed inlet and discharge outlet are respectively located at the upper part of the first end and the end of the U-shaped trough. The first-stage suspension-flushing separation mechanism is located below the feed inlet and above the single-shaft, double-shaft, or multi-shaft spiral mechanism within the U-shaped trough. The first stage of the coal gangue separation mechanism is used to immediately suspend and separate the coal gangue material falling from the feed inlet. The second stage of the suspension and separation mechanism is set at the bottom of the U-shaped trough or inside the trough. Its function is to perform a second stage of suspension and separation on the settled gangue slag. After the coal gangue entering the U-shaped trough is suspended and separated by the first stage suspension and separation mechanism, and the settled gangue slag is separated by the second stage suspension and separation mechanism, the suspended coal material is extracted by the coal material lifting and filtering device. The separated settled gangue slag is pushed to the discharge port at the end of the U-shaped trough by a single-shaft, double-shaft, or multi-shaft screw mechanism and then extracted by the raw black soil lifting and filtering device.

[0024] Furthermore, the filtration mechanism mainly includes a flow-guiding separation filter screen and concentrated and dilute phase liquid outlets, which are located above the spiral mechanism in the end of the U-shaped trough of the suspension and turbidity separation device. The filter screen separates the suspension containing a large number of particles in the latter part of the U-shaped trough into a concentrated phase (enriched liquid containing suspended coal particles, etc.) and a dilute phase (circulating heavy medium solution). The dilute phase liquid outlet of the filtration mechanism is connected to the inlet of the circulation pump via a pipeline. The outlet of the circulation pump is connected to the inlets of the first-stage suspension and turbidity separation mechanism and the second-stage turbidity suspension separation mechanism in the U-shaped trough via pipelines. The concentrated phase liquid outlet of the filtration mechanism is connected to the inlet of the concentrated phase pump of the coal material filtration device via a pipeline. Its function is to continuously extract and purify suspended fine particles such as coal dust in the U-shaped trough.

[0025] Furthermore, the coal filtration device mainly includes a filter screen, filter bucket, filter plate, or spiral suspension coal extraction mechanism, a vibrating filtration mechanism, and a dense phase pump. The discharge port of the coal extraction mechanism is connected to the feed end of the vibrating filtration mechanism, and the discharge port of the dense phase pump is connected to the feed end of the vibrating filtration mechanism via a pipeline. The vibrating filtration mechanism mainly includes a vibrating filter (plate / screen / cloth) screen, a clean water sprayer, and a filtrate collection tank. The clean water sprayer and the filtrate collection tank are respectively located at the upper and lower parts of the vibrating screen. Their function is to filter and clean the coal extracted by the coal extraction mechanism and the coal dust extracted by the dense phase pump, to separate the coal, and to recover the waste liquid containing the suspended separation medium and humic mud. The waste liquid outlet of the filtrate collection tank is connected to the feed end of the humic fertilizer filtration device via a pipeline.

[0026] Furthermore, the raw black soil filtration device mainly includes a filter bucket type or chain plate type / chain mesh type or spiral type lifting mechanism and a vibration filtration and washing mechanism. The discharge port of the lifting mechanism is connected to the feed end of the vibration filtration and washing mechanism. The vibration filtration and washing mechanism mainly includes a vibrating filter (plate / mesh / cloth) screen, a clean water sprayer, and a filtrate collection tank. The clean water sprayer and the filtrate collection tank are respectively set at the upper and lower parts of the vibrating filter screen. Their function is to filter and wash the shale gangue (raw black soil) extracted by the raw black soil extraction mechanism to obtain raw black soil and recover the waste liquid containing suspended separation medium and humic mud. The waste liquid outlet of the filtrate collection tank is connected to the feed end of the humic fertilizer filtration device through a pipeline.

[0027] Furthermore, the humic fertilizer filtration device mainly includes a single-layer or multi-layer vibration dewatering mechanism, a wastewater collection mechanism, and a humic sludge collection and discharge mechanism. The wastewater collection mechanism is located at the lower part of each layer of vibration dewatering mechanism and is connected to the wastewater outlet. The humic sludge collection and discharge mechanism is located at the end of each layer of vibration dewatering mechanism and is connected to the humic sludge discharge port. Waste liquid containing suspended separation medium and humic sludge from the coal filtration device and the raw black soil filtration device is sent to the vibration dewatering mechanism. The wastewater containing suspended separation medium is recovered by the wastewater collection mechanism and sent to the suspended separation medium liquid replenishment device. The dewatered humic sludge is collected and discharged from the discharge port to obtain humic fertilizer.

[0028] Furthermore, the suspension separation medium solution replenishment device mainly includes a tank, a suspension separation medium feeding mechanism, a clean water replenishment mechanism, a vortex stirring mechanism, a suspension separation medium liquid supply pump, and a wastewater inlet; the suspension separation medium feeding mechanism mainly includes a bag breaking mechanism and a discharge port, the suspension separation medium feeding mechanism is located at the top or upper side wall of the tank, and the discharge port of the suspension separation medium feeding mechanism is connected to the inside of the tank; the clean water replenishment mechanism mainly includes a water tank, a water inlet, a cleaning water outlet, a replenishment water outlet, and a cleaning pump, the clean water replenishment mechanism is located at the upper part or outer side of the tank, and the cleaning water outlet is connected to the inside of the tank. The cleaning pump is connected to the inlet of the clean water sprayer of the coal filtration device and the raw black soil filtration device via pipelines. The water supply outlet is connected to the tank of the suspension separation medium solution replenishment device via a pipeline or a transfer pump. The vortex stirring mechanism mainly includes a vortex pump, which is installed inside or outside the tank. When installed outside the tank, the inlet and outlet of the vortex pump are connected to the tank via pipelines to generate a vortex / vortex stirring effect inside the tank. The inlet and outlet of the suspension medium liquid replenishment pump are connected to the tank of the suspension separation medium solution replenishment device and the U-shaped trough of the suspension swirl separation device via pipelines.

[0029] Furthermore, the equipment for decarbonizing coal gangue to produce primary black soil and humic fertilizer can be configured in stages as a clean coal filtration device and a carbon-containing material filtration device, which can extract suspended carbon-containing materials at different liquid surface depths in the U-shaped tank of the suspension slurry separation device in stages to obtain coal materials of different grades (different coal content, different calorific values); the outlet of the dense phase pump is connected to the feed end of the vibration filter washing mechanism of the carbon-containing material filtration device through a pipeline.

[0030] Furthermore, the equipment for decarbonizing coal gangue to produce primary black soil and humic fertilizer can be configured in stages as a coal filtration device, a carbonaceous material filtration device, and a coal dust filtration device. The coal filtration device and the carbonaceous material filtration device extract suspended carbonaceous materials at different liquid levels in the U-shaped tank of the suspension washing separation device in stages to obtain coal materials of different grades (different coal content, different calorific values). The outlet of the dense phase pump and the waste liquid outlet of the filtrate collection tank of the vibration washing mechanism of the coal filtration device and the carbonaceous material filtration device are connected to the feed end of the coal dust filtration device through pipelines. The waste liquid outlet of the coal dust filtration device is connected to the feed end of the humic fertilizer filtration device through pipelines or a transfer pump to recover nitrogen-based media and humic fertilizer.

[0031] Furthermore, the equipment for decarbonizing coal gangue to produce native black soil and humic fertilizer can also be equipped with a pneumatic agitation device on its suspension and agitation separation device to pneumatically agitate and disperse the gangue slag in the suspension medium solution.

[0032] Furthermore, the equipment system for decarbonizing coal gangue to produce primary black soil and humic fertilizer can also be equipped with a coal gangue crushing and screening pretreatment device, or a selective crushing device to remove hard lumps, or a selective crushing device to remove hard lumps and a strong magnetic separation device to remove sulfide minerals.

[0033] The beneficial effects of the present invention are as follows: (1) Based on the requirement that black soil and humic fertilizer must not contain excessive levels of toxic and harmful substances such as chlorine, fluorine, sulfur, alkali (sodium) and heavy metal elements and organic pollutants, and the mineral composition characteristics of coal gangue, the present invention selects a nitrogen-based medium that is non-flammable, non-toxic, odorless, and free of harmful elements such as fluorine, chlorine, sulfur, phosphorus, alkali and heavy metals and organic pollutants. The medium is prepared into a solution with a density of 1.35 to 1.7 g / cm3 as an environmentally friendly suspension separation medium for decarbonization of coal gangue. This lays the foundation for efficient and pollution-free decarbonization and detoxification of coal gangue, which is conducive to the large-scale and effective utilization of coal gangue and the efficient production of ecologically safe black soil and humic fertilizer; (2) The process and equipment are relatively simple, the coal and slag (raw black soil) are thoroughly separated, the equipment investment is low, and the operating cost is low; (3) The present invention solves the pollution problems of conventional coal preparation flotation process and heavy medium flotation, with no harmful waste residue discharge and no wastewater or waste gas discharge, which is a green and environmentally friendly process. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the side cross-section structure of the equipment in Embodiment 1 of the present invention;

[0035] Figure 2 for Figure 1 The diagram shown is a schematic diagram of the structure at point AA of the equipment in Embodiment 1 of the present invention;

[0036] Figure 3 for Figure 1 The diagram shown is a structural schematic of the BB section of the equipment in Embodiment 1 of the present invention;

[0037] Figure 4 for Figure 1 The diagram shown is a schematic diagram of the connection structure of the suspension separation medium solution replenishment device equipped in Embodiment 1 of the present invention;

[0038] Figure 5 for Figure 1 The diagram shown is a schematic diagram of the installation structure of the filtration mechanism in the U-shaped groove of Embodiment 1 of the present invention.

[0039] Figure 6 This is a schematic diagram of the side cross-section structure of the equipment in Embodiment 2 of the present invention;

[0040] Figure 7 for Figure 6 The diagram shown is a top view of the equipment in Embodiment 2 of the present invention;

[0041] Figure 8This is a schematic diagram of the side cross-section structure of the equipment in Embodiment 3 of the present invention;

[0042] Figure 9 for Figure 8 The diagram shown is a schematic diagram of the CC section of the equipment in Embodiment 3 of the present invention;

[0043] Figure 10 for Figure 8 The diagram shows the structure of the DD section of the equipment in Embodiment 3 of the present invention.

[0044] In the diagram, 1-Suspension-flushing separation device, 11-U-shaped trough, 12-Spiral mechanism, 13-First-stage suspension-flushing separation mechanism, 14-Second-stage flushing-suspension separation mechanism, 15-Filtration mechanism, 151-Guiding separation filter screen, 152-Concentrated liquid outlet, 153-Decent liquid outlet, 16-Circulation pump, 16'-Circulation pump ①, 16”-Circulation pump ②, 17-Inlet, 18-Discharge port, 2-Coal material filtration device, 21-Coal material extraction mechanism, 22-Vibrating filter washing mechanism, 221-Vibrating filter screen, 222-Clear water sprayer, 223-Filtration collection tank, 2'-Clean coal filtration device, 21'-Clean coal lifting mechanism, 22'-Vibrating filter washing mechanism, 2”-Carbon-containing material filtration device, 21”-Carbon-containing material lifting mechanism 22” - Vibration filtration and washing mechanism, 23 - Dense phase pump, 3 - Raw black soil filtration device, 31 - Lifting mechanism, 32 - Vibration filtration and washing mechanism, 321 - Vibration filter screen, 322 - Clean water sprayer, 323 - Filtrate collection tank, 4 - Humus fertilizer filtration device, 41 - Vibration dewatering mechanism, 42 - Wastewater collection mechanism, 43 - Humus sludge collection and discharge mechanism, 431 - Humus sludge discharge port, 5 - Suspension separation medium solution adjustment and replenishment device, 51 - Tank, 52 - Suspension medium feeding mechanism, 53 - Clean water replenishment mechanism, 531 - Water tank, 532 - Water inlet, 533 - Cleaning water outlet, 534 - Water replenishment outlet, 535 - Cleaning pump, 54 - Swirl mixing mechanism, 55 - Suspension separation medium solution replenishment pump, 56 - Wastewater inlet. Detailed Implementation

[0045] The present invention will be further described below with reference to the embodiments.

[0046] The performance testing of the coal, raw black soil, and humus fertilizer products obtained in each embodiment was conducted according to the testing methods and specifications specified in the following standards: "Chemical Analysis Methods for Fly Ash and Coal Gangue for Building Materials" (GB / T 27974-2011), "Determination of Lead and Cadmium in Soil Quality - Graphite Furnace Atomic Absorption Spectrophotometry" (GB / T 17141-1997), "Determination of Total Mercury in Soil Quality - Cold Atomic Absorption Spectrophotometry" (GB / T 17136-1997), "Determination of 12 Metallic Elements in Soil and Sediments - Aqua Regia Extraction-Inductively Coupled Plasma Mass Spectrometry" (HJ 803-2016), "Determination of Copper, Zinc, Lead, Nickel, and Chromium in Soil and Sediments - Flame Atomic Absorption Spectrophotometry" (HJ 491-2019), "Determination of Inorganic Elements in Soil and Sediments - Wavelength Dispersive X-ray Fluorescence Spectrometry" (HJ780-2015), and "Determination of Soil pH Value - Potentiometric Method" (HJ Standards include GB / T 213-2008 (962-2018), GB / T 213-2008 (Method for Determination of Calorific Value of Coal), GB 15618-2018 (Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control), and GB 38400-2019 (Limits for Toxic and Hazardous Substances in Fertilizers). Example 1

[0047] This embodiment describes a method for decarbonizing coal gangue to produce raw black soil and humus fertilizer, with the following main steps:

[0048] (1) Preparation of suspension separation medium: Manganese nitrate, ferric nitrate, potassium nitrate, water-soluble dechlorination amino acid powder (CAS number 65072-01-7), polyglutamic acid γ-PGA, and chitosan oligosaccharide, which are non-flammable, non-toxic, odorless, and free of harmful elements such as fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, and organic pollutants, are mixed and dissolved in water to prepare a solution with a density of 1.51 g / cm³. 3 The solution is used as an environmentally friendly suspension separation medium for decarbonization of coal gangue;

[0049] (2) Coal gangue preparation: Coal gangue from a certain place in Guizhou was selected. The calorific value of the coal gangue on an air-dry basis was about 1400 kcal / kg. Multiple samples were taken and analyzed to be shale-type coal gangue. No sulfide ore, no coal-coal-coal mixture or hard block material was found. The coal gangue particles with a maximum particle size of about 102 mm were directly used as raw materials for producing black soil and humic fertilizer.

[0050] (3) Decarbonization to produce raw black soil and humus fertilizer:

[0051] The following dual-shaft spiral suspension and turbulence separation device is used. An environmentally friendly suspension separation medium solution is injected into the U-shaped trough 11 of the suspension and turbulence separation device 1. Coal gangue particles are continuously added into the U-shaped trough 11 of the suspension and turbulence separation device 1 from the feed inlet. The coal gangue material falling into the suspension separation medium solution from the feed inlet is immediately subjected to the first-stage suspension and turbulence separation, so that most of the coal material is separated and suspended in time. The gangue slag at the bottom is subjected to the second-stage turbulence and suspension separation. After the coal gangue is suspended and turbulently separated by the first-stage suspension and turbulence separation mechanism and the gangue slag at the bottom is turbulent and suspended by the second-stage turbulence and suspension separation mechanism, the suspended coal material is extracted, washed, and dewatered by the coal material filtration device 2. The waste liquid containing the suspension separation medium and humic mud is recovered. The decarbonized coal material obtained is about 19.8% of the coal gangue feed amount, and the dry basis calorific value of the decarbonized coal material is about 3882 kcal / kg.

[0052] The gangue slag, after being separated by a secondary slurry, is extracted, washed, and dewatered by a raw black soil filtration device 3. The waste liquid containing the suspended separation medium and humic mud is recovered to produce raw black soil, which is about 78.4% of the coal gangue feed weight.

[0053] The waste liquid containing suspended separation medium and humic mud is fed into the vibration dewatering mechanism of the humic fertilizer filtration device 4. The wastewater containing suspended separation medium is collected by the wastewater collection mechanism and sent to the suspended separation medium solution replenishment device 5. The dewatered humic mud is collected and discharged from the outlet, and humic fertilizer with a content of about 1.9% of the coal gangue feed is obtained.

[0054] Reference Figures 1 to 5 In Example 1, the equipment for producing raw black soil and humic fertilizer by decarbonizing coal gangue includes a suspension-flushing separation device 1, a coal material filtration device 2, a raw black soil filtration device 3, a humic fertilizer filtration device 4, and a suspension separation medium solution replenishment device 5. The coal material filtration device 2 is located above the suspension-flushing separation device 1 and is connected to the U-shaped trough 11 of the suspension-flushing separation device 1. The raw black soil filtration device 3 is located at the end of the U-shaped trough 11 of the suspension-flushing separation device 1 and is connected to its discharge port 18. The feed inlet of the humic fertilizer filtration device 4 is connected to the filtrate outlet of the coal material filtration device 2 and the raw black soil filtration device 3 through a pipeline. The circulating wastewater inlet of the suspension separation medium solution replenishment device 5 is connected to the wastewater outlet of the humic fertilizer filtration device 4 through a pipeline. The heavy medium solution outlet of the suspension separation medium solution replenishment device 5 is connected to the suspension-flushing separation device 1 through a pipeline.

[0055] The suspension and turbulence separation device 1 includes a U-shaped trough 11, a twin-shaft spiral mechanism 12, a first-stage suspension and turbulence separation mechanism 13, a second-stage turbulence and suspension separation mechanism 14, a filtration mechanism 15, a circulating pump 16, a feed inlet 17, and a discharge port 18. The twin-shaft spiral mechanism 12 is located at the bottom of the U-shaped trough 11, agitating and pushing the settled coal gangue material towards the end. The feed inlet 17 and discharge port 18 are respectively located at the upper part of the first end and the end of the U-shaped trough 11. The first-stage suspension and turbulence separation device 14... The sloshing separation mechanism 13 is located below the feed inlet 17 and above the double-shaft screw mechanism 12 within the U-shaped trough 11, performing immediate suspension and sloshing separation on the coal gangue material falling from the feed inlet 17. The second-stage sloshing suspension separation mechanism 14 is located within the U-shaped trough 11, performing second-stage sloshing suspension separation on the bottom gangue slag. The coal gangue entering the U-shaped trough 11 is suspended and sloshed by the first-stage sloshing separation mechanism 13, and the bottom gangue slag is sloshed by the second-stage sloshing suspension separation mechanism 14. After suspension separation, the suspended coal is extracted by the coal extraction filter 2, and the separated and settled gangue slag is pushed by the twin-shaft screw mechanism 12 to the discharge port 18 at the end of the U-shaped trough 11 and then into the raw black soil extraction device 3 for extraction; the filtration mechanism 15 includes a flow-guiding separation filter screen 151 and a concentrated phase liquid outlet 152 and a dilute phase liquid outlet 153, which is set above the screw mechanism 12 in the end of the U-shaped trough 11, and guides and separates the suspension containing a large number of particles in the latter part of the U-shaped trough 11 into a concentrated phase (enriched with suspended coal particles, etc.). The filter mechanism 15 has a dilute phase and a light phase (circulating jet heavy medium solution). The dilute phase liquid outlet 153 of the filter mechanism 15 is connected to the inlet of the circulating pump 16 via a pipeline. The outlet of the circulating pump 16 is connected to the inlet of the first-stage suspension turbulence separation mechanism 13 and the second-stage turbulence suspension separation mechanism 14 in the U-shaped tank 11 via pipelines. The concentrated phase liquid outlet 152 of the filter mechanism 15 is connected to the inlet of the concentrated phase pump 23 of the coal material filtration device 2 via a pipeline. The filter mechanism continuously extracts and purifies suspended fine particles such as coal dust in the U-shaped tank 11.

[0056] The coal extraction and filtration device 2 includes a filter bucket-type suspended coal extraction mechanism 21, a vibrating filter washing mechanism 22, and a dense phase pump 23. The discharge port of the coal extraction mechanism 21 is connected to the feed end of the vibrating filter washing mechanism 22, and the discharge port of the dense phase pump 23 is connected to the feed end of the vibrating filter washing mechanism 22 via a pipeline. The vibrating filter washing mechanism 22 mainly includes a vibrating filter screen 221, a clean water sprayer 222, and a filtrate collection tank 223. The clean water sprayer 222 and the filtrate collection tank 223 are respectively set at the upper and lower parts of the vibrating filter screen 221 to filter and wash the coal extracted by the coal extraction mechanism 2 and the coal dust extracted by the dense phase pump 23, thus separating the coal. It also recovers the waste liquid containing suspended media and humic mud. The waste liquid outlet of the filtrate collection tank 223 is connected to the feed end of the humic fertilizer extraction and filtration device 4 via a pipeline.

[0057] The raw black soil extraction and filtration device 3 includes a filter bucket lifting mechanism 31 and a vibration filtration and washing mechanism 32. The discharge port of the lifting mechanism 31 is connected to the feed end of the vibration filtration and washing mechanism 32. The vibration filtration and washing mechanism 32 mainly includes a vibrating filter screen 321, a clean water sprayer 322, and a filtrate collection tank 323. The clean water sprayer 322 and the filtrate collection tank 323 are respectively set at the upper and lower parts of the vibrating filter screen 321 to filter and wash the shale gangue (raw black soil) extracted by the raw black soil extraction mechanism 31 to obtain raw black soil. The waste liquid containing suspended media and humic mud is recovered. The waste liquid outlet of the filtrate collection tank 323 is connected to the feed end of the humic fertilizer extraction and filtration device 4 through a pipeline.

[0058] The humic fertilizer extraction and filtration device 4 includes a two-layer vibration dewatering mechanism 41, a wastewater collection mechanism 42, and a humic sludge collection and discharge mechanism 43. The wastewater collection mechanism 42 is located at the lower part of each layer of vibration dewatering mechanism 41 and is connected to the wastewater outlet 421. The humic sludge collection and discharge mechanism 43 is located at the end of each layer of vibration dewatering mechanism 41 and is connected to the humic sludge discharge port 431. Waste liquid containing suspended media and humic sludge from the coal extraction and filtration device 2 and the raw black soil extraction and filtration device 3 is sent into the vibration dewatering mechanism 41. The wastewater containing suspended media is recovered by the wastewater collection mechanism 42 and sent to the suspended media liquid replenishment device 5. The dewatered humic sludge is collected and discharged from the humic sludge discharge port 431 to obtain humic fertilizer.

[0059] The suspension separation medium solution replenishment device 5 includes a tank 51, a suspension separation medium feeding mechanism 52, a clean water replenishment mechanism 53, a vortex stirring mechanism 54, a suspension separation medium solution replenishment pump 55, and a wastewater inlet 56. The suspension separation medium feeding mechanism 52 includes a bag-breaking mechanism 521 and a discharge port 522. The bag-breaking mechanism 521 uses a commercially available unpacking machine. The suspension separation medium feeding mechanism 52 is located at the top of the tank 51, and the discharge port 522 of the suspension separation medium feeding mechanism 52 is connected to the inside of the tank 51. The clean water replenishment mechanism 53 includes a water tank 531, a water inlet 532, a cleaning water outlet 533, a replenishment water outlet 534, and a cleaning pump 535. 53 is located at the top of the tank 51. The cleaning water outlet 533 is connected to the clean water spray inlet of the coal filter 2 and the raw black soil filter 3 via a cleaning pump 535. The water replenishment outlet 534 is connected to the tank 51 of the suspension separation medium solution replenishment device 5 via a pipe and a valve. The swirling stirring mechanism 54 includes a swirling pump 541. When it is located outside the tank 51, the inlet and outlet of the swirling pump 541 are connected to the inside of the tank 51 via pipes, so that a swirling stirring effect is generated inside the tank. The inlet and outlet of the suspension separation medium liquid replenishment pump 55 are connected to the inside of the tank 51 of the suspension separation medium solution replenishment device 5 and the U-shaped groove 11 of the suspension swirl separation device 1 via pipes.

[0060] (1) The harmful components of the raw black soil prepared using the above-mentioned apparatus were tested, and the results are as follows: pH=6.8

[0061]

[0062] According to the above indicators, the raw black soil produced meets the relevant national standards for soil environmental quality. The toxic and harmful substances and pollutants in the raw black soil produced do not exceed the standards. At the same time, the raw black soil separated using nitrogen-based suspension media has elements that are more suitable for plant growth, meets the conditions and requirements for producing raw black soil from coal gangue, and completely avoids the toxic and harmful effects on plants caused by conventional coal preparation heavy media.

[0063] (2) The humic fertilizer prepared using the above-mentioned device was tested for toxic and harmful substances, and the results are as follows:

[0064]

[0065] According to the above indicators, the humic fertilizer produced meets the national standards for the restriction of toxic and harmful pollutants in fertilizers. At the same time, the raw black soil sorted using nitrogen-based suspension media has elements that are more suitable for plant growth, meeting the conditions and requirements for humic fertilizer production from coal gangue, and completely avoiding the toxic and harmful effects on plants caused by conventional coal washing heavy media. Example 2

[0066] This embodiment uses a mixture of non-flammable, non-toxic, odorless, and free from harmful elements and organic pollutants such as fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, manganese nitrate, potassium nitrate, polyglutamic acid γ-PGA, chitosan oligosaccharide, and a complex amino acid compound (rich in glycine, lysine, glutamic acid, and leucine) with CAS number 26048-69-1, dissolved in water to prepare a solution with a density of 1.59 g / cm³. 3 The solution was used as an environmentally friendly suspension separation medium for decarbonizing coal gangue. Coal gangue from a certain area in Guizhou was selected. The dry calorific value of the coal gangue was about 1194 kcal / kg. Multiple samples were taken and analyzed to be shale-type coal gangue. No sulfide ore, no coal-coal / coal-stone mixtures, and no hard lumps were found. The maximum particle size of the gangue was about 85 mm. It was directly used as raw material for producing black soil and humic fertilizer.

[0067] Reference Figure 6 and Figure 7The equipment used in this embodiment for decarbonizing coal gangue to produce raw black soil and humic mud differs from the equipment used in Embodiment 1 mainly in that: the coal extraction and filtration device 2 is set in two stages, namely: a clean coal extraction and filtration device 2' and a carbon-containing material extraction and filtration device 2''. The clean coal extraction and filtration device 2' extends 200mm below the liquid surface of the medium in the U-shaped trough 11 to extract clean coal. The content of the extracted clean coal is approximately 4.9% of the coal gangue feed amount, and the dry basis calorific value of the clean coal is 5390 kcal / kg; the carbon-containing material... The filter device 2” extends 300 mm below the liquid level of the medium in the U-shaped trough 11 to extract carbonaceous material. The extracted carbonaceous material content is approximately 11.7% of the coal gangue feed amount, and the dry basis calorific value of the carbonaceous material is 2128 kcal / kg. The clean coal filter device 2' includes a filter bucket type clean coal lifting mechanism 21' and a vibrating filter washing mechanism 22'. The carbonaceous material filter device 2” includes a filter bucket type carbonaceous material lifting mechanism 21”, a vibrating filter washing mechanism 22”, and a dense phase pump 23. The dense phase pump in this embodiment... The discharge port of pump 23 is connected to the feed end of the vibration washing mechanism 22” of the carbon-containing material filtration device 2” via a pipeline. In this embodiment, the second-stage turbulent suspension separation mechanism 14 is configured as two stages: a second-stage turbulent suspension separation mechanism ① 14' and a second-stage turbulent suspension separation mechanism ② 14”. The second-stage turbulent suspension separation mechanisms ① and ② turbulent at turbulent pressures of 0.25 MPa and 0.21 MPa respectively. The second-stage turbulent suspension separation mechanism ① is located below the clean coal filtration device 2', and the second-stage turbulent suspension separation mechanism ② is located below the carbon-containing material filtration device 2”. The dilute liquid outlet 153 of the filtration mechanism 15 is connected to the inlets of circulating pump 16, circulating pump ① 16', and circulating pump ② 16” via pipelines. The outlets of circulating pump 16, circulating pump ① 16', and circulating pump ② 16” are connected to the first-stage suspension turbulent separation mechanism 13, the second-stage turbulent suspension separation mechanism ① 14', and the second-stage turbulent suspension separation mechanism ② 14” within the U-shaped trough 11. The raw black soil filtration device 3 uses a tubular screw lifting mechanism 31 and a vibration filtration and washing mechanism 32. The feed inlet of the tubular screw lifting mechanism 31 is connected to the discharge port 18 at the end of the U-shaped trough 11. In this embodiment, the raw black soil accounts for 79.9% of the coal gangue feed amount; the humic fertilizer accounts for 3.7% of the coal gangue feed amount.

[0068] (1) The harmful components of the raw black soil prepared using the above-mentioned apparatus were tested, and the results are as follows: pH=7.3:

[0069]

[0070] According to the above indicators, the raw black soil produced meets the relevant national standards for soil environmental quality. The toxic and harmful substances and pollutants in the raw black soil produced do not exceed the standards. At the same time, the raw black soil separated using nitrogen-based suspension media has elements that are more suitable for plant growth, meets the conditions and requirements for producing raw black soil from coal gangue, and completely avoids the toxic and harmful effects on plants caused by conventional coal preparation heavy media.

[0071] (2) The humic mud prepared by the above-mentioned apparatus was subjected to a commissioned test for toxic and harmful substances, and the results are as follows:

[0072]

[0073] According to the above indicators, the humic fertilizer produced meets the national standards for the restriction of toxic and harmful pollutants in fertilizers. At the same time, the raw black soil sorted using nitrogen-based suspension media has elements that are more suitable for plant growth, meeting the conditions and requirements for humic fertilizer production from coal gangue, and completely avoiding the toxic and harmful effects on plants caused by conventional coal washing heavy media. Example 3

[0074] This embodiment uses a mixture of non-flammable, non-toxic, odorless, and free from harmful elements and organic pollutants such as fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, manganese nitrate, ferric nitrate, polyglutamic acid γ-PGA, chitosan oligosaccharide, and a complex amino acid compound (rich in glycine, lysine, glutamic acid, and leucine) with CAS number 26048-69-1, dissolved in water to prepare a solution with a density of 1.68 g / cm³. 3 The solution was used as an environmentally friendly suspension separation medium for decarbonizing coal gangue. Coal gangue from a certain area in Guizhou was selected. The dry calorific value of the coal gangue was about 932 kcal / kg. Multiple samples were taken and analyzed. The coal gangue was classified as shale and contained a small amount of pyrite. Most of the harmful sulfide ores were removed by magnetic separation. Hard blocks >100mm were selectively crushed and separated as building material raw materials, and coal gangue ≤100mm was used as raw material for producing black soil and humic fertilizer.

[0075] Reference Figures 8 to 10 The equipment shown for decarbonizing coal gangue to produce black soil and humic fertilizer differs from that in Example 1 in that the coal material filtration device 2 in this example is configured as a fine coal filtration device 2', a carbon-containing material filtration device 2" and a coal powder filtration device 6. The fine coal filtration device 2' and the carbon-containing material filtration device 2" extract suspended carbon-containing materials at different liquid surface depths in the U-shaped tank 11 of the suspension slurry separation device 1 in stages. The content of the fine coal obtained is 3.2% of the coal gangue feed amount, and the dry basis calorific value of the fine coal is 4860 kcal / kg. The content of the carbon-containing material obtained is 12.2% of the coal gangue feed amount, and the dry basis calorific value of the carbon-containing material is 1935 kcal / kg.

[0076] The discharge port of the dense phase pump 23 and the waste liquid outlet of the filtrate collection tank of the vibrating filter washing mechanism of the fine coal filtration device 2' and the carbonaceous material filtration device 2'" are connected to the feed end of the coal powder filtration device 6 through a pipeline. The waste liquid outlet of the coal powder filtration device 6, which collects coal powder, is connected to the feed end of the humic fertilizer filtration device 4 through a pipeline and a conveying pump to recover nitrogen-based media and humic fertilizer. In this embodiment, the raw black soil accounts for 81.2% of the coal gangue feed; the humic fertilizer accounts for 3.5% of the coal gangue feed.

[0077] (1) The raw black soil prepared using the above-mentioned apparatus was tested for harmful components, and the results are as follows: pH=7.1:

[0078]

[0079] According to the above indicators, the raw black soil produced meets the relevant national standards for soil environmental quality. The toxic and harmful substances and pollutants in the raw black soil produced do not exceed the standards. At the same time, the raw black soil separated using nitrogen-based suspension media has elements that are more suitable for plant growth, meets the conditions and requirements for producing raw black soil from coal gangue, and completely avoids the toxic and harmful effects on plants caused by conventional coal preparation heavy media.

[0080] (2) The humic mud prepared using the above-mentioned apparatus was subjected to a commissioned test for toxic and harmful substances, and the results are as follows:

[0081]

[0082] According to the above indicators, the humic fertilizer produced meets the national standards for the restriction of toxic and harmful pollutants in fertilizers. At the same time, the raw black soil sorted using nitrogen-based suspension media has elements that are more suitable for plant growth, meeting the conditions and requirements for humic fertilizer production from coal gangue, and completely avoiding the toxic and harmful effects on plants caused by conventional coal washing heavy media.

Claims

1. A method for decarbonizing coal gangue to produce raw black soil and humus fertilizer, characterized in that, The main steps include: (1) Preparation of suspension separation medium: Based on the requirement that raw black soil and humus fertilizer must not contain excessive levels of toxic and harmful substances such as chlorine, fluorine, sulfur, alkali, heavy metals, and organic pollutants, and considering the mineral composition characteristics of coal gangue, a nitrogen-based medium that is non-flammable, non-toxic, odorless, and free of fluorine, chlorine, sulfur, phosphorus, alkali, heavy metals, and organic pollutants is selected, dissolved in water, and prepared to have a density of 1.35–1.7 g / cm³. 3 The solution is used as an environmentally friendly suspension separation medium for decarbonization of coal gangue; (2) Coal gangue preparation: 1) For coal gangue from shale mining areas, if no sulfide ore, no coal-coal mixture or hard lumps are found, and the coal gangue particles with a particle size ≤150mm are used directly; 2) For shale-type coal gangue containing a small amount of pyrite, most of the harmful sulfide ores are removed by magnetic separation. The hard blocks >100mm are selectively crushed and separated as building material raw materials, and the coal gangue granules ≤100mm are reserved for later use. (3) Decarbonization to produce raw black soil and humus fertilizer: 1) A suspension swirl separation device is used to disperse coal gangue particles in an environmentally friendly suspension separation medium to separate coal and gangue. The environmentally friendly suspension separation medium obtained in step (1) is injected into the U-shaped trough of the suspension swirl separation device. Coal gangue particles are continuously added into the U-shaped trough of the suspension swirl separation device from the feed inlet. The coal gangue particles falling into the suspension medium from the feed inlet are immediately subjected to the first-stage suspension swirl separation, so that most of the coal is separated and suspended in time. The gangue slag at the bottom is subjected to the second-stage swirl suspension separation. The suspended coal is extracted, washed, and dewatered by the coal filter device to obtain coal obtained from the decarbonization of coal gangue. The waste liquid containing the suspension separation medium and humic mud is recovered. 2) The gangue slag separated by the secondary flushing suspension separation medium is extracted, washed, and dewatered by the raw black soil filtration device to obtain raw black soil and recover the waste liquid containing the suspension separation medium and humic mud. 3) The recovered waste liquid containing suspended separation medium and humic sludge is sent to the vibration dewatering mechanism of the humic fertilizer filtration device. The wastewater containing suspended separation medium is recovered by the wastewater collection mechanism and sent to the suspended separation medium solution replenishment device. The dewatered humic sludge is discharged from the outlet to obtain humic fertilizer.

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