Filling process and filling material for flotation tailing slime utilization

Abstract

The invention relates to the technical field of coal mine filling, in particular to a filling process and a filling material for utilization of flotation tailing slime, the filling process aims at filling and utilization of flotation tailing slime, coal gangue, fly ash and flotation tailing slime generated in the coal production, processing and utilization process are comprehensively utilized, and the filling material is used for filling and utilization of the flotation tailing slime. The filling material which can be conveyed by a pipeline is prepared by adding cement and water, and is used for filling a coal mine goaf, so that the purposes of consuming and utilizing flotation tailing slime and supporting an overlying rock layer to control surface deformation are achieved. According to the method, flotation tailing slime can be consumed and utilized in a large-scale mode, land occupation caused by tailing slime stockpiling of a coal mine is reduced, meanwhile, the raw material filling cost can be reduced, surface subsidence is controlled, and the method has high practical value and practical significance for protecting the ecological environment of a mining area.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine filling, and in particular to a filling process and a filling material for utilizing flotation tailing coal slime. Background Art

[0002] Coal mining, washing, processing and utilization will produce wastes such as gangue, tailings, and fly ash. At present, the application of gangue and fly ash in the field of coal mine filling has been relatively extensive, forming a reliable filling and utilization method. However, the research and practice of flotation tailings in the field of filling is still very lacking. Flotation tailings are high-ash waste produced by coal mine flotation operations. With the transformation of coal preparation plants across the country in recent years to improve the ash content and clean coal recovery rate of tailings, the ash content of tailings has increased to more than 70%. Most coal preparation plants produce tailings with an ash content of more than 80% and a calorific value of less than 500 kcal. Due to the low content of combustible organic matter, it can no longer be sold as fuel, resulting in a large amount of flotation tailings in coal mines. The tailings occupy a large amount of land, and long-term open-air stacking will also produce dust and other pollutants to the air environment in the mining area. Therefore, there is an urgent need for a treatment method that can realize the large-scale consumption and utilization of flotation tailings.

[0003] Patent CN111042859A "A method for in-situ filling of coal slurry water in deep mines and coal slurry water cemented filling material" proposes a method for in-situ filling of coal slurry water in deep mines, but the concentrated coal slurry water only accounts for 10% to 25% of the total mass of the raw materials excluding water, and the coal slurry water processing volume is small; and subject to the limitation of underground space, more than 80% of the coal slurry water is the output of flotation operations of ground coal preparation plants, which leads to a large amount of flotation tail coal slurry being accumulated in the form of solid on the land of the mining area, which is difficult to consume and utilize; and this method needs to add additives such as early strength agent and water reducer, and the particle size requirement of coal gangue is too high (≤5mm), which will lead to a substantial increase in filling cost and a decrease in operating efficiency, causing inconvenience to its popularization and use.

[0004] To this end, this application targets the current trend of coal mine transformation and development towards green mining, combines the advantages of filling mining to reduce subsidence and control losses and large-scale consumption of waste, and takes into account low cost, high efficiency and large-scale utilization, and proposes a filling process and material preparation method for the utilization of flotation tailings slime, which can realize the large-scale consumption and utilization of flotation tailings slime, and has important practical value and realistic significance for reducing the cost of filling materials, releasing the land occupied by tailings slime, and protecting the ecological environment of mining areas. Summary of the invention

[0005] In order to make up for the deficiencies in the prior art, the present invention provides a filling material and a filling process for utilizing flotation tailings slime.

[0006] A filling material for flotation tail coal slime, the raw material components of the filling material include: flotation tail coal slime, coal gangue, fly ash, cement and water: The flotation tailings are high-ash tailings produced by flotation operations in coal mines and coal preparation plants, with an ash content of more than 70% and a calorific value of less than 500 kcal. The coal gangue is a block of solid waste discharged during the coal mining and coal washing processes; The fly ash is powder captured from flue gas in coal-fired power plants, and grade I or grade II fly ash is used; The cement is PO42.5 ordinary Portland cement.

[0007] The mass proportion of the raw materials is: Coal gangue 15%~50%, fly ash 10%~35%, flotation tailings slime 5%~20%, cement 5%~20%, water 20%~26%. The total mass of the above raw materials accounts for 100%.

[0008] A filling process for utilizing flotation tailings slime comprises the following steps: S1, the flotation tail coal slime filter cake after clarification, concentration, filtration and dehydration in the coal preparation plant flotation process or the existing stockpiled flotation tail coal slime is transported to the filling station via a belt conveyor, and then the coal slime is crushed by a crusher, and the crushed tail coal slime particles are stored in the tail coal slime silo for standby use; S2, storing the purchased fly ash in a fly ash silo for standby use; S3, storing the raw gangue produced by the coal mine in the raw gangue bin, sending the raw gangue to the crushing and screening machine through the feeder and the belt conveyor for crushing and screening, and storing the crushed gangue particles that meet the particle size requirements in the finished gangue bin for standby use; S4, storing the mine water in a reservoir for future use; S5, weighing the raw materials according to the determined raw material ratio, and putting them into a mixer for thorough mixing; S6, using a filling pump to pump the evenly mixed filling material through the filling pipeline to the goaf for filling.

[0009] Further, in order to better realize the present invention, the maximum particle size of the crushed coal gangue particles is less than 20 mm, of which 0-5 mm accounts for 35%-75%, 5-10 mm accounts for 15%-35%, and 10-20 mm accounts for 10%-20%; The maximum particle size of the tailings slime particles after crushing is less than 10 mm, of which those less than 5 mm account for more than 90%.

[0010] The beneficial effects of the present invention are: The present invention takes the filling and utilization of flotation tailings as the starting point, takes into account the three main wastes of coal gangue, flotation tailings and fly ash generated in the process of coal mining, processing and utilization, and adopts the filling method to realize the large-scale disposal and utilization of wastes, which can solve the problem that the existing flotation tailings occupy a large amount of land and pollute the ecological environment of the mining area due to the difficulty in large-scale treatment. The method is simple, easy to operate, has low material requirements, and can meet the corresponding index requirements without the use of any additives. The filling cost is lower and it is easy to promote. It has important practical value for promoting the coordinated development of green coal transformation and ecological environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the filling process of the present invention; Figure 2 Partial proportioning scheme for preparing filling materials of the present invention; Figure 3 It is the performance index of some proportioning schemes for preparing filling materials of the present invention. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0013] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0014] Figure 1This is a specific embodiment of the present invention, which is a filling process method for the utilization of flotation tailings. In this embodiment, flotation tailings, coal gangue, fly ash, cement and water are used to prepare filling materials. Flotation tailings are high-ash tailings produced by flotation operations in coal mines and coal preparation plants, with an ash content of more than 70% and a calorific value of less than 500 kcal; coal gangue is a block solid waste discharged during coal mining and coal washing; fly ash is powder captured in the flue gas of coal-fired power plants, using grade I or grade II fly ash; cement is PO42.5 ordinary Portland cement. The mass proportion of each raw material is: 10% to 50% for coal gangue, 10% to 35% for fly ash, 5% to 25% for flotation tailings, 5% to 20% for cement, and 20% to 26% for water. The total mass proportion of the above raw materials is 100%. The performance of filling materials prepared with different raw material ratios is different. The appropriate ratio scheme can be selected according to the output of coal gangue, flotation tailings slime, and fly ash, the availability of raw materials, and the performance requirements of the filling materials. Generally speaking, coal mine filling mining requires the filling materials to have the following properties: slump>18cm, stratification ≤2cm, static water seepage rate<5%, and 28-day compressive strength>2.0MPa.

[0015] The specific filling process of this embodiment is as follows: (1) The flotation tailings coal slime filter cake or the existing stockpiled flotation tailings coal slime after clarification, concentration, filtration and dehydration in the coal preparation plant flotation process is transported to the filling station via a belt conveyor, and then the coal slime is crushed once by a crusher, and the crushed tailings coal slime particles are stored in the tailings coal slime silo for standby use; (2) Storing Class I or Class II fly ash purchased from coal-fired power plants in fly ash silos for future use; (3) The raw gangue produced by the coal mine preparation plant is stored in the raw gangue bin, and the raw gangue is sent to the crushing and screening machine through the feeder and belt conveyor for crushing and screening, and the crushed gangue that meets the particle size requirements is stored in the finished gangue bin for standby use; (4) Storing mine water in a reservoir for future use; (5) Weighing each raw material according to the determined raw material ratio, and then putting it into a mixer to mix the raw materials thoroughly; (6) Use a filling pump to pump the evenly mixed filling material through the filling pipeline to the goaf for filling.

[0016] Furthermore, in order to reduce the probability of pipe blockage during pipeline pumping and ensure good gangue grading, the maximum particle size of the crushed coal gangue is required to be less than 20mm, of which 0-5mm accounts for 35%-75%, 5-10mm accounts for 15%-35%, and 10-20mm accounts for 10%-20%. Generally, the maximum discharge particle size of the crusher is adjusted to 20mm for crushing to obtain the naturally graded gangue that meets the requirements; because the tailings coal slime will harden into blocks of different sizes after dehydration, in order to ensure uniform mixing of the materials, the maximum particle size of the flotation tailings coal slime particles after crushing is required to be less than 10mm, of which the proportion of less than 5mm should be more than 90%. Generally, the maximum discharge particle size of the crusher is adjusted to 10mm for one crushing to meet the requirements.

[0017] like Figure 2 Figure 3 As shown in the figure, the coal gangue used in each mix ratio scheme is the natural graded gangue after one crushing, of which 0-5mm accounts for 54.4%, 5-10mm accounts for 31.6%, and 10-20mm accounts for 14.0%; the fly ash used is the ordinary II grade fly ash produced by the coal-fired power plant; the flotation tail coal slime is crushed to less than 10mm, of which 0-5mm tail coal slime particles account for 97.2%; the cement is the commercially available PO42.5 ordinary Portland cement. Figure 3 It can be seen from the data in that the filling material prepared by the material preparation method for flotation tailings slime filling provided in this embodiment has excellent performance and can meet the relevant requirements of coal mine filling mining on the performance of filling materials.

[0018] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A filling material for flotation tailings slime, the raw material components of the filling material comprising: Flotation tailings coal slime, coal gangue, fly ash, cement and water, characterized by: The flotation tailings are high-ash tailings produced by flotation operations in coal mines and coal preparation plants, with an ash content of more than 70% and a calorific value of less than 500 kcal. The coal gangue is a block of solid waste discharged during the coal mining and coal washing processes; The fly ash is powder captured from flue gas in coal-fired power plants, and grade I or grade II fly ash is used; The cement is PO42.5 ordinary Portland cement.

2. The filling material for flotation tailings slime utilization according to claim 1, characterized in that The mass proportion of the raw materials is: Gangue 15%~50%, fly ash 10%~35%, flotation tailings slime 5%~20%, cement 5%~20%, water 20%~26%. The total mass of the above raw materials accounts for 100%.

3. A filling process for utilizing flotation tailings slime, characterized in that: The following steps are involved: S1, the flotation tail coal slime filter cake after clarification, concentration, filtration and dehydration in the coal preparation plant flotation process or the existing stockpiled flotation tail coal slime is transported to the filling station via a belt conveyor, and then the coal slime is crushed by a crusher, and the crushed tail coal slime particles are stored in the tail coal slime silo for standby use; S2, storing the purchased fly ash in a fly ash silo for standby use; S3, storing the raw gangue produced by the coal mine in the raw gangue bin, sending the raw gangue to the crushing and screening machine through the feeder and the belt conveyor for crushing and screening, and storing the crushed gangue particles that meet the particle size requirements in the finished gangue bin for standby use; S4, storing the mine water in a reservoir for future use; S5, weighing the raw materials according to the determined raw material ratio, and putting them into a mixer for thorough mixing; S6, using a filling pump to pump the evenly mixed filling material through the filling pipeline to the goaf for filling.

4. The filling process for utilizing flotation tailings slime according to claim 3 is characterized in that: The maximum particle size of the crushed coal gangue particles is less than 20 mm, of which 0-5 mm accounts for 35%-75%, 5-10 mm accounts for 15%-35%, and 10-20 mm accounts for 10%-20%; The maximum particle size of the tailings slime particles after crushing is less than 10 mm, of which those less than 5 mm account for more than 90%.

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