CN117505469A - A harmless and safe treatment method for coal gangue - Google Patents

Abstract

The invention relates to the technical field of solid waste treatment, in particular to a harmless and safe treatment method of coal gangue. The harmless safe treatment method provided by the invention comprises the following steps: mixing the heavy metal passivating agent with the gangue particles for innocent treatment to obtain the gangue particles after heavy metal passivation; the heavy metal passivating agent is prepared by sequentially molding and calcining preparation raw materials comprising coal gangue, fly ash, limestone, gypsum and mirabilite; mixing the coal gangue particles after heavy metal passivation, the flame retardant slurry and water for safe treatment; the flame retardant in the flame retardant slurry comprises calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, silica fume and borax. The treatment method can realize harmless and safe treatment of the coal gangue.

Description

A harmless and safe treatment method for coal gangue

Technical field

The present invention relates to the technical field of solid waste treatment, and in particular to a harmless and safe treatment method of coal gangue.

Background technique

Coal gangue is a solid waste emitted during the coal mining process. It is a gray-black rock with lower carbon content and harder than coal that is associated with the coal seam during the coal formation process. It includes a mixture of carbonaceous, argillaceous and sandy shale, with a low calorific value, containing 20% to 30% carbon, and some contain humic acid. Coal gangue is divided into clay rock, sandstone, carbonate and aluminous rock according to its main mineral content. According to the source and final state, coal gangue emissions vary greatly depending on coal seam conditions, mining conditions and washing processes. Generally, excavation gangue accounts for about 10% of raw coal production, and coal preparation gangue accounts for 12% to 18% of selected raw coal. %. The inorganic components of coal gangue are mainly silicon, aluminum, calcium, magnesium, iron oxides and some rare metals. The percentage of its chemical composition is: SiO ₂ is 52 to 65%; Al ₂ O ₃ is 16 to 36%; Fe ₂ O ₃ is 2.28 to 14.63%; CaO is 0.42 to 2.32%; MgO is 0.44 to 2.41 %; TiO ₂ is 0.90~4%; P ₂ O ₅ is 0.007~0.24%; K ₂ O+Na ₂ O is 1.45~3.9%; V ₂ O ₅ is 0.008~0.03%.

In addition to carbon, coal gangue also has a mineral that can easily cause harm and safety hazards, pyrite. Its composition is mainly in macroscopic forms such as nodules, granules, and lumps. The pyrite present in coal has been washed After selection, most of it is concentrated in the washed waste. When the gangue is crushed to less than 3mm, about 80% of the pyrite can be dissociated, and when the gangue is crushed to less than 1mm, almost all of it is dissociated. There are very few scattered pyrites, mostly in the form of 0.02mm cubic single crystals, which are embedded in the network vein rock and are difficult to separate from the gangue. In principle, the recovery method and process flow of pyrite is to crush the pyrite into monomers and dissociate it from coarse to fine, and then recover it.

There are several ways to utilize coal gangue: 1) Recover coal and pyrite: through simple processes, good coal is washed out of coal gangue, inferior coal is selected through screening, and pyrite is picked out at the same time. Or recover pyrite, washed coal and medium coal from the jig-plane shaker process used for coal preparation. The recovered coal can be used as fuel for power boilers, the washed gangue can be used as building materials, and the pyrite can be used as chemical raw materials; 2) Used for power generation: mainly mixed-fired power generation with washed coal and washed gangue. China has used boiling furnaces to burn a mixture of washed coal and washed gangue (with a calorific value of about 2,000 kcal per kilogram) to generate electricity. Slag can be used to produce slag bricks and slag cement; 3) Manufacturing building materials: instead of clay as a raw material for brick making, less fertile land can be dug. When burning bricks, coal gangue can be saved by using the combustible material itself. Gangue sintered hollow bricks refer to bricks with vertical holes (porosity is not less than 25%, small size and large number of holes) made from shale, gangue or fly ash as the main raw material after roasting. Coal gangue can partially or completely replace the clay component in the production of ordinary cement. Spontaneously or artificially burned coal gangue has certain activity and can be used as an active mixing material for cement to produce ordinary Portland cement (with a dosage of less than 20%), pozzolanic cement (with a dosage of 20-50%) and low clinker. Cement (amount greater than 50%). It can also be directly ground with lime and gypsum in appropriate proportions to form clinker-free cement, which can be used as a cementing material. Boiling slag is used as aggregate or gravel and boiling slag are used as coarse and fine aggregates to make concrete blocks or concrete hollow masonry blocks. Blocks and other building materials. The United Kingdom, Belgium and other countries have factories that use coal gangue instead of siliceous raw materials to produce cement. Crystalline aluminum chloride can be obtained by leaching with hydrochloric acid. The residue after leaching is mainly silica, which can be used as raw material for the production of rubber fillers and wet production of water glass. The rare elements (such as germanium, gallium, vanadium, uranium, etc.) contained in the remaining mother liquor determine their extraction value depending on their content. In addition, coal gangue can also be used to produce low calorific value gas, make ceramics, make soil conditioners, or be used for paving, underground filling, and ground filling to create land. Grass and afforestation can also be planted on the gangue mountain after spontaneous combustion to beautify the environment; 4) Used to prepare ecological materials: Coal gangue contains about 15-20% of trace elements such as Zn, Cu, Mn and B, porous minerals and 15-25% % organic matter, can be used to develop organic compound fertilizers and microbial fertilizers, increase the content of trace elements and humic acid in the soil, increase the porosity and permeability of the soil, enhance the nitrogen fixation capacity of the soil and soil fertility, thereby increasing crop yields. It can also be used as a cultivation substrate in soilless cultivation of crops. Coal gangue is rich in nutrients needed by a variety of plants. As a substrate raw material, it can provide more nutrients for crop growth and improve the physical and chemical properties of the substrate; 5) Used in the production of chemicals product. Coal gangue is rich in SiO ₂ and Al ₂ O ₃ and can be used to produce aluminum, silicon and other chemical products, such as alum, sodium silicate, aluminum chloride, etc. Using coal gangue with high aluminum content as raw material to produce alumina can alleviate the shortage of bauxite resources and realize high value-added utilization of coal gangue. Among them, Cui Li et al. (Cui Li. Research on the preparation of polyaluminum chloride flocculant by comprehensive utilization of coal gangue [D]; Shanxi University, 2009.) Polyaluminum chloride flocculant prepared from coal gangue as raw material is used for purification High salinity mine water finally meets the drinking water quality requirements.

The open-air stacking of coal gangue will generate a large amount of dust. This is mainly because the coal gangue piled on the ground will be weathered and crushed after being exposed to the sun and rain for a long time. In addition, the coal gangue will disintegrate after absorbing water, which can easily generate dust. Under the influence of wind, the quality of the atmosphere in the mining area will be deteriorated. In addition, coal gangue contains combustible materials such as residual coal, carbonaceous mudstone and waste wood, among which carbon and sulfur can form the material basis for spontaneous combustion of coal gangue. The coal gangue business is stacked in the open. Over time, the heat inside the gangue mountain gradually accumulates. When the temperature reaches the burning point of combustibles, the remaining coal in the gangue pile can spontaneously ignite. After spontaneous combustion, the internal temperature of the gangue mountain is 800-1000°C, causing the gangue to fuse and release a large amount of harmful gases such as CO, CO ₂ , SO ₂ , H ₂ S, NO _x , and SO ₂ is the main one. The spontaneous combustion of a waste rock mountain can last for more than ten years to several decades. The emission of these harmful gases not only reduces the ambient air quality around the gangue mountain and affects the health of residents in the mining area, but also often affects the surrounding ecological environment, causing trees to grow slowly, pests and diseases to increase, and crop yields to decrease or even die.

In addition to major elements such as dust, SiO ₂ , A1 ₂ O ₃ and Fe, Mn, coal gangue also contains other trace heavy metal elements, such as Pb, Sn, As, Cr, etc. These elements are toxic heavy metal elements. When mountains of coal gangue stacked in the open air are eroded by rainwater, acidic water is produced, polluting the surrounding land and water bodies. When the waste pile is unreasonably stacked, the slope of the waste pile is prone to instability, leading to collapse and slippage of the waste pile. Especially during heavy rain seasons, this phenomenon is particularly common in mountainous areas, and debris flows are prone to occur, thus causing serious consequences. The safety of farmland, rivers and people downstream.

Long-term accumulation of large amounts of coal gangue not only occupies a large amount of land, but also spontaneously combusts to produce toxic and harmful gases such as sulfur dioxide and hydrogen sulfide, forming acid rain and harming the local ecological environment. At the same time, geological disasters and environmental disasters such as collapse and explosion will occur. In this regard, large-scale, safe, and harmless treatment and disposal technologies and methods for coal gangue in goaf filling, ground foundation construction, subsidence pit backfilling, and mine pit filling are particularly effective and important.

Contents of the invention

The object of the present invention is to provide a harmless and safe treatment method of coal gangue, which can realize the harmless and safe treatment of coal gangue.

In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

The invention provides a harmless and safe treatment method for coal gangue, which includes the following steps:

A heavy metal passivator and gangue particles are mixed for harmless treatment to obtain heavy metal passivated gangue particles; the heavy metal passivator is prepared from raw materials including gangue, fly ash, limestone, gypsum and thenardite in sequence Prepared by molding and calcination;

The heavy metal passivated coal gangue particles, flame retardant slurry and water are mixed for safe treatment; the flame retardant in the flame retardant slurry includes calcium silicate, iron powder, calcium oxide, silica sol, Calcium sulfate, aluminum sulfate, silica fume and borax.

Preferably, the gangue particles include medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm.

Preferably, the mass ratio of the heavy metal passivator and gangue particles is (1-5):100.

Preferably, the mass ratio of the gangue, fly ash, limestone, gypsum and thenardite is 100: (50~120): (40~80): (40~75): (3~10).

Preferably, the calcination temperature is 900-1100°C, and the holding time is 30-90 minutes.

Preferably, after the calcination is completed, cooling, grinding and sieving are performed in sequence.

Preferably, the mass ratio of calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax is 100: (5～10): (30～50): (20～ 70): (20～60): (15～50): (15～45): (15～45).

Preferably, the flame retardant slurry includes flame retardant and water;

The mass ratio of the flame retardant and water is 1: (1.0~3.0).

Preferably, the mass ratio of the gangue particles, flame retardant slurry and water after heavy metal passivation is 100: (5-10): (40-70).

The invention provides a harmless and safe treatment method for coal gangue, which includes the following steps: mixing a heavy metal passivator and coal gangue particles for harmless treatment to obtain heavy metal passivated coal gangue particles; the heavy metal passivation The chemical agent is prepared by sequentially molding and calcining raw materials including coal gangue, fly ash, limestone, gypsum and thenardite; the heavy metal passivated gangue particles, flame retardant slurry and water are mixed for safe treatment ; The flame retardant in the flame retardant slurry includes calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax. The present invention uses a heavy metal passivator to inhibit the migration of heavy metals in coal gangue, and uses a flame retardant to prevent carbon and sulfur in coal gangue from spontaneous combustion in a humid oxidizing environment, thereby achieving harmless and safe treatment of coal gangue. It provides a new idea for the harmless and safe treatment and disposal of coal gangue, which is large in volume, wide in scope and low in comprehensive utilization.

Description of drawings

Figure 1 is a schematic process flow diagram of the harmless and safe treatment of coal gangue according to the present invention;

Figure 2 is a schematic flow diagram of the preparation process of the heavy metal passivator of the present invention;

Figure 3 is a schematic flow diagram of the preparation process of the flame retardant of the present invention.

Detailed ways

As shown in Figure 1, the present invention provides a harmless and safe treatment method for coal gangue, which includes the following steps:

A heavy metal passivator and gangue particles are mixed for harmless treatment to obtain heavy metal passivated gangue particles; the heavy metal passivator is prepared from raw materials including gangue, fly ash, limestone, gypsum and thenardite in sequence Prepared by molding and calcination;

The heavy metal passivated coal gangue particles, flame retardant slurry and water are mixed for safe treatment; the flame retardant in the flame retardant slurry includes calcium silicate, iron powder, calcium oxide, silica sol, Calcium sulfate, aluminum sulfate, silica fume and borax.

In the present invention, unless otherwise stated, all raw materials are commercially available products well known to those skilled in the art.

The present invention mixes heavy metal passivating agent and gangue particles for harmless treatment to obtain heavy metal passivated gangue particles; the heavy metal passivating agent is prepared from a process including gangue, fly ash, limestone, gypsum and mirabilite. The raw materials are prepared by molding and calcining in sequence.

In the present invention, the gangue particles (corresponding to the medium and fine particle levels in Figure 1) preferably include medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm; in the present invention, the medium gravel There are no special restrictions on the ratio of fine gravel to fine gravel, just mix it in any ratio. In the present invention, the gangue particles are preferably prepared by crushing coal gangue; the present invention does not have any special restrictions on the crushing process, and adopts processes well known to those skilled in the art to ensure that the particles obtained after crushing are The coal gangue particles may include the above-mentioned medium gravel and fine gravel.

In the present invention, the coal gangue is preferably the solid waste produced during the excavation or washing process and the combustion process of coal.

In the present invention, the particle size of the heavy metal passivating agent is preferably 80 to 120 mesh, more preferably 90 to 110 mesh, and most preferably 100 mesh.

In the present invention, the heavy metal passivator is prepared by sequentially shaping and calcining raw materials including coal gangue, fly ash, limestone, gypsum and thenardite (as shown in Figure 2). The mass ratio of the gangue, fly ash, limestone, gypsum and thenardite is preferably 100: (50~120): (40~80): (40~75): (3~10), more preferably 100: (60～100): (50～70): (50～65): (4～8), most preferably 100: (70～80): (55～65): (55～60): (5～ 6). In the present invention, the fly ash is preferably the solid waste produced during the excavation or washing process and the combustion process of coal. In the present invention, the purity of calcium carbonate in the limestone is preferably ≥98.0wt%; the purity of calcium sulfate dihydrate in the gypsum is preferably ≥96.0wt%; the purity of sodium sulfate decahydrate in the sodium salt is preferably ≥98.0wt% .

The present invention does not have any special limitations on the molding process, and it can be carried out using processes well known to those skilled in the art.

In the present invention, the calcination temperature is preferably 900-1100°C, more preferably 950-1050°C, and most preferably 980-1020°C; the holding time is preferably 30-90min, more preferably 40-80min, most preferably It is 50~60min.

After the calcination is completed, the present invention preferably also includes cooling, grinding (as shown in Figure 2) and sieving in sequence; the present invention does not have any special limitations on the cooling process, and adopts methods well known to those skilled in the art. The process is carried out and the temperature of the surface of the material reaches below 45°C. The present invention does not have any special limitations on the grinding process, and it can be carried out using processes well known to those skilled in the art. In the present invention, the sieving is preferably 100 mesh sieve.

In the present invention, the mass ratio of the heavy metal passivator and gangue particles is preferably (1-5):100, more preferably (2-4):100, and most preferably (2.5-3.5):100.

In the present invention, the mixing of the heavy metal passivating agent and coal gangue is preferably carried out under stirring conditions. The present invention does not have any special limitations on the stirring process, and it can be carried out by using processes well known to those skilled in the art. In the present invention, during the mixing process, the heavy metals in the coal gangue form stable heavy metal salts under the action of the passivating agent, which prevents the heavy metals from being released into the soil during the coal gangue backfilling process.

After obtaining heavy metal-passivated coal gangue particles, the present invention mixes the heavy metal-passivated coal gangue particles, flame retardant slurry and water for safe treatment; the flame retardant in the flame retardant slurry includes Calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax.

In the present invention, the flame retardant slurry preferably includes a flame retardant and water, and the mass ratio of the flame retardant and water is preferably 1: (1.0~3.0), more preferably 1: (1.5~2.5) , the most preferred is 1: (1.8～2.2). In the present invention, the flame retardant includes calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax; the calcium silicate, iron powder, calcium oxide, silica sol , the mass ratio of calcium sulfate, aluminum sulfate, microsilica powder and borax is preferably 100: (5～10): (30～50): (20～70): (20～60): (15～50): ( 15～45): (15～45), more preferably 100: (6～9): (35～45): (30～60): (30～50): (20～40): (20～40 ): (20～40), most preferably 100: (7～8): (38～42): (40～50): (35～45): (25～35): (25～35): ( 25～35). In the present invention, the preparation method of the flame retardant preferably includes mixing calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax, followed by drying and cooling ( As shown in Figure 3); the present invention does not have any special restrictions on the mixing process, and it can be carried out by using processes well known to those skilled in the art; the present invention does not have any special restrictions on the drying process, and it can be carried out using this method. It is sufficient to carry out a process well known to those skilled in the art and ensure that the moisture content of the flame retardant obtained after drying is in the range of 2.0 to 5.5 wt%. The present invention does not have any special limitations on the cooling process, and it can be carried out by using processes well known to those skilled in the art.

In the present invention, the preparation method of the flame retardant slurry preferably includes mixing the flame retardant and water. The mixing is preferably performed under stirring conditions; the stirring speed is preferably 75 to 150 rpm, more preferably 80 to 130 rpm, and most preferably 90 to 100 rpm; the stirring time It is preferably 30 to 150 min, more preferably 60 to 120 min, and most preferably 90 min.

In the present invention, the mass ratio of the heavy metal passivated gangue particles, flame retardant slurry and water is preferably 100: (5~10): (40~70), and more preferably 100: (6~ 9): (45~65), the most preferred is that the mass ratio of heavy metal passivated coal gangue particles, flame retardant slurry and water is 100: (7~8): (50~60).

The harmless and safe treatment method of coal gangue provided by the present invention will be described in detail below with reference to the examples, but they should not be understood as limiting the protection scope of the present invention.

Example 1

A large coal gangue in Chifeng, Inner Mongolia: In terms of mass parts, the main ingredients include: silica 43.01%, aluminum oxide 31.63%, sodium oxide 1.83%, potassium oxide 1.54%, calcium oxide 1.04%, magnesium oxide 0.73%, Carbon content 11.82%, sulfur 1.82% and balance water and organic matter;

The coal gangue is crushed to obtain medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm with a mass ratio of 1:0.65;

According to the mass ratio of 100:100:40:40:3, coal gangue (solid waste produced during the excavation or washing process of coal and during the combustion process), fly ash (coal during the excavation or washing process and solid waste produced during the combustion process), limestone (calcium carbonate purity 98.5wt%), gypsum (calcium sulfate dihydrate purity 96.80wt%) and Glauber's salt (sodium sulfate decahydrate purity 99wt%) are mixed, and then molded in sequence. , calcining (the calcination temperature is 1050°C, and the time is 1 hour), cooled to 35°C, ball milled and passed through a 100-mesh sieve to obtain a heavy metal passivator;

According to the mass ratio of 2:100, stir and mix the medium gravel with a particle size of 64 to 256 mm and the fine gravel with a particle size of 2 to 64 mm with a heavy metal passivation agent at a mass ratio of 1:0.65 to obtain heavy metal passivated coal. Gangue particles;

According to the mass ratio of 100:5:30:20:20:15:15:15, combine calcium silicate (industrial grade), iron powder (industrial grade), calcium oxide (industrial grade), silica sol (industrial grade), Calcium sulfate (industrial grade), aluminum sulfate (industrial grade), microsilica powder (industrial grade) and borax (industrial grade) are mixed evenly and dried to obtain a flame retardant with a moisture content of 2.45wt%;

According to the mass ratio of 1:1.2, the flame retardant and water are stirred and mixed at a rotation speed of 110 rpm and a time of 60 min to obtain a flame retardant slurry;

According to the mass ratio of 100:5:55, the heavy metalized coal gangue particles, flame retardant slurry and water are mixed for harmless and safe treatment and safe backfilling (meeting the "Hazardous Waste Identification Standard" GB5085-2007 Limit requirements for heavy metals and the effect of long-term handling and stacking of non-spontaneous combustion).

Example 2

Coal gangue from a place in Datong, Shanxi: In terms of mass parts, the main ingredients include: silica 44.92%, aluminum oxide 37.08%, sodium oxide 1.94%, potassium oxide 1.41%, calcium oxide 1.93%, magnesium oxide 1.03%, Sulfur 1.93% and balance water and organic matter;

The coal gangue is crushed to obtain medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm with a mass ratio of 1:1.11;

According to the mass ratio of 100:75:60:55:4.5, coal gangue (solid waste produced during the excavation or washing process of coal and during the combustion process), fly ash (coal during the excavation or washing process and the solid waste produced during the combustion process), limestone (calcium carbonate purity 99wt%), gypsum (calcium sulfate dihydrate purity 98.5wt%) and Glauber's salt (sodium sulfate decahydrate purity 99.50wt%) are mixed and then formed. , calcining (the calcination temperature is 1025°C, the time is 55min), cooled to 37.5°C, ball milled and passed through a 100-mesh sieve to obtain a heavy metal passivator;

According to the mass ratio of 1:65, stir and mix the medium gravel with a particle size of 64 to 256 mm and the fine gravel with a particle size of 2 to 64 mm with a heavy metal passivation agent at a mass ratio of 1:1.11 to obtain heavy metal passivated coal. Gangue particles;

According to the mass ratio of 100:7.5:35:27:30:25:30:25, combine calcium silicate (industrial grade), iron powder (industrial grade), calcium oxide (industrial grade), silica sol (industrial grade), Calcium sulfate (industrial grade), aluminum sulfate (industrial grade), microsilica powder (industrial grade) and borax (industrial grade) are mixed evenly and dried to obtain a flame retardant with a moisture content of 3.5wt%;

According to the mass ratio of 1:2.5, the flame retardant and water are stirred and mixed at a rotation speed of 75 rpm and a time of 90 min to obtain a flame retardant slurry;

According to the mass ratio of 100:6.5:50, the heavy metalized coal gangue particles, flame retardant slurry and water are mixed for harmless and safe treatment and safe backfilling (meeting the "Hazardous Waste Identification Standard" GB5085-2007 Heavy Metal limit requirements and the effect of long-term storage and non-spontaneous combustion).

Example 3

A coal gangue in Baotou, Inner Mongolia: In terms of parts by mass, the main ingredients include: silica 55.58%, aluminum oxide 25.21%, sodium oxide 1.72%, potassium oxide 0.65%, calcium oxide 1.93%, magnesium oxide 1.60%, carbon Content 11.14%, sulfur 1.72% and balance water;

The coal gangue is crushed to obtain medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm with a mass ratio of 1:0.85;

According to the mass ratio of 100:70:60:65:7, coal gangue (solid waste produced during the excavation or washing process of coal and during the combustion process), fly ash (coal during the excavation or washing process and solid waste produced during the combustion process), limestone (calcium carbonate purity 99wt%), gypsum (calcium sulfate dihydrate purity 97.5wt%) and Glauber's salt (sodium sulfate decahydrate purity 99.50wt%) are mixed and then molded. , calcining (the calcination temperature is 975°C, the time is 80min), cooled to 40°C, ball milled and passed through a 100-mesh sieve to obtain a heavy metal passivator;

According to the mass ratio of 1:75, stir and mix the medium gravel with a particle size of 64-256mm and the fine gravel with a particle size of 2-64mm with a mass ratio of 1:1.11 and a heavy metal passivation agent to obtain heavy metal passivated coal. Gangue particles;

According to the mass ratio of 100:6.5:40:55:38:28.5:40:35, combine calcium silicate (industrial grade), iron powder (industrial grade), calcium oxide (industrial grade), silica sol (industrial grade), Calcium sulfate (industrial grade), aluminum sulfate (industrial grade), microsilica powder (industrial grade) and borax (industrial grade) are mixed evenly and dried to obtain a flame retardant with a moisture content of 4.5wt%;

According to the mass ratio of 1:1.5, the flame retardant and water are stirred and mixed at a rotation speed of 85 rpm and a time of 70 min to obtain a flame retardant slurry;

According to the mass ratio of 100:6.5:60, the heavy metalized coal gangue particles, flame retardant slurry and water are mixed for harmless and safe treatment and safe backfilling (meeting the "Hazardous Waste Identification Standard" GB5085-2007 Heavy Metal limit requirements and the effect of long-term storage and non-spontaneous combustion).

Example 4

Coal gangue in Fengfeng Coal Mining Area, Hebei: In terms of mass parts, the main ingredients include: silica 56.82%, aluminum oxide 25.78%, sodium oxide 3.38%, potassium oxide 1.68%, calcium oxide 1.78%, magnesium oxide 0.85% , 2.03% sulfur and the balance moisture and organic matter;

The coal gangue is crushed to obtain medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm with a mass ratio of 1:0.95;

According to the mass ratio of 100:80:60:45:5, coal gangue (solid waste produced during the excavation or washing process of coal and during the combustion process), fly ash (coal during the excavation or washing process and solid waste produced during the combustion process), limestone (calcium carbonate purity: 98wt%), gypsum (calcium sulfate dihydrate purity: 96wt%) and Glauber's salt (sodium sulfate decahydrate purity: 98.50wt%) are mixed and then formed. , calcining (the calcination temperature is 950°C and the time is 90min), cooled to 34.5°C, ball milled and passed through a 100-mesh sieve to obtain a heavy metal passivator;

According to the mass ratio of 1:65, stir and mix the medium gravel with a particle size of 64 to 256 mm and the fine gravel with a particle size of 2 to 64 mm with a heavy metal passivation agent at a mass ratio of 1:0.95 to obtain heavy metal passivated coal. Gangue particles;

According to the mass ratio of 100:6.5:35:44:25.5:40:35:27.5, combine calcium silicate (industrial grade), iron powder (industrial grade), calcium oxide (industrial grade), silica sol (industrial grade), Calcium sulfate (industrial grade), aluminum sulfate (industrial grade), microsilica powder (industrial grade) and borax (industrial grade) are mixed evenly and dried to obtain a flame retardant with a moisture content of 3.5wt%;

According to the mass ratio of 1:2.5, the flame retardant and water are stirred and mixed at a rotation speed of 135 rpm and a time of 60 min to obtain a flame retardant slurry;

According to the mass ratio of 100:6.5:47.5, the heavy metalized coal gangue particles, flame retardant slurry and water are mixed for harmless and safe treatment and safe backfilling (meeting the "Hazardous Waste Identification Standard" GB5085-2007 Heavy Metal limit requirements and the effect of long-term storage and non-spontaneous combustion).

Example 5

A certain coal gangue in Guizhou: In terms of parts by mass, the main ingredients include: silica 56.45%, aluminum oxide 15.93%, sodium oxide 2.92%, potassium oxide 1.45%, calcium oxide 0.76%, magnesium oxide 0.58%, carbon content 14.82%, sulfur 3.92% and balance water;

The coal gangue is crushed to obtain medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm with a mass ratio of 1:1.15;

According to the mass ratio of 100:110:75:75:10, coal gangue (solid waste produced during the excavation or washing process of coal and during the combustion process), fly ash (coal during the excavation or washing process and solid waste produced during the combustion process), limestone (calcium carbonate purity 99wt%), gypsum (calcium sulfate dihydrate purity 97.5wt%) and Glauber's salt (sodium sulfate decahydrate purity 99.50wt%) are mixed, and then molded in sequence. , calcining (the calcination temperature is 915°C, the time is 85min), cooled to 44°C, ball milled and passed through a 100-mesh sieve to obtain a heavy metal passivator;

According to the mass ratio of 1:85, stir and mix the medium gravel with a particle size of 64 to 256 mm and the fine gravel with a particle size of 2 to 64 mm with a heavy metal passivation agent at a mass ratio of 1:1.15 to obtain heavy metal passivated coal. Gangue particles;

According to the mass ratio of 100:10:50:70:60:50:45:45, combine calcium silicate (industrial grade), iron powder (industrial grade), calcium oxide (industrial grade), silica sol (industrial grade), Calcium sulfate (industrial grade), aluminum sulfate (industrial grade), microsilica powder (industrial grade) and borax (industrial grade) are mixed evenly and dried to obtain a flame retardant with a moisture content of 5.5wt%;

According to the mass ratio of 1:2.5, the flame retardant and water are stirred and mixed at a rotation speed of 150 rpm and a time of 70 min to obtain a flame retardant slurry;

According to the mass ratio of 100:10:70, the heavy metalized coal gangue particles, flame retardant slurry and water are mixed for harmless and safe treatment and safe backfilling (meeting the "Hazardous Waste Identification Standard" GB5085-2007 Heavy Metal limit requirements and the effect of long-term storage and non-spontaneous combustion).

The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications can also be made. should be regarded as the protection scope of the present invention.

Claims (9)

1. A harmless and safe treatment method for coal gangue, which is characterized in that it includes the following steps: A heavy metal passivator and gangue particles are mixed for harmless treatment to obtain heavy metal passivated gangue particles; the heavy metal passivator is prepared from raw materials including gangue, fly ash, limestone, gypsum and thenardite in sequence Prepared by molding and calcination; The heavy metal passivated coal gangue particles, flame retardant slurry and water are mixed for safe treatment; the flame retardant in the flame retardant slurry includes calcium silicate, iron powder, calcium oxide, silica sol, Calcium sulfate, aluminum sulfate, silica fume and borax. 2. The harmless and safe treatment method according to claim 1, wherein the gangue particles include medium gravel with a particle size of 64 to 256 mm and fine gravel with a particle size of 2 to 64 mm. 3. The harmless and safe treatment method according to claim 1, characterized in that the mass ratio of the heavy metal passivator and gangue particles is (1-5):100. 4. The harmless and safe treatment method according to claim 1, characterized in that the mass ratio of the coal gangue, fly ash, limestone, gypsum and thenardite is 100: (50~120): (40~80 ): (40～75): (3～10). 5. The harmless and safe treatment method according to claim 1 or 4, characterized in that the calcination temperature is 900-1100°C, and the holding time is 30-90 minutes. 6. The harmless and safe treatment method according to claim 5, characterized in that after the calcination is completed, it also includes cooling, grinding and sieving in sequence. 7. The harmless and safe treatment method as claimed in claim 1, characterized in that the mass ratio of the calcium silicate, iron powder, calcium oxide, silica sol, calcium sulfate, aluminum sulfate, microsilica powder and borax is 100: (5～10): (30～50): (20～70): (20～60): (15～50): (15～45): (15～45). 8. The harmless and safe treatment method according to claim 1 or 7, wherein the flame retardant slurry includes flame retardant and water; The mass ratio of the flame retardant and water is 1: (1.0~3.0). 9. The harmless and safe treatment method according to claim 1, characterized in that the mass ratio of the gangue particles, flame retardant slurry and water after the heavy metal passivation is 100: (5-10): (40～70).