A carbon fixation filling method based on synchronous mining of coal-aluminum symbiotic deposit

Abstract

The application discloses a kind of carbon sequestration filling methods based on coal-aluminum symbiotic deposit synchronous mining, belong to mining technical field.The method includes the following steps: S1, lower layer aluminum ore and upper layer coal mine synchronous mining;S2, the coal gangue generated by coal mining is crushed and used as filling aggregate;S3, the carbon sequestration and alkali removal treatment of red mud generated by aluminum smelting is used as filling cementitious material;S4, two kinds of treated solid waste are mixed and cement is proportioned to meet the relevant national standards of filling material;S5, pumped to coal mine and aluminum mine goaf through pipeline system, realize carbon sequestration filling.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of synchronous exploitation of carbon fixation filling method based on coal-aluminum paragenetic deposit, belong to mining technical field. BACKGROUND

[0002] While industrial production of alumina, a large amount of solid waste, red mud, will be generated, due to the production process of each aluminum smelter is different, about 1t of alumina is produced, 1.0~1.8t of red mud will be discharged. Red mud produced by Bayer process accounts for more than 90% of the total amount of red mud discharged.

[0003] Coal gangue is a kind of solid waste discharged in the process of coal mining and washing, compared with ordinary coal, it has the characteristics of low carbon content, low calorific value and hard texture, and is a kind of mine solid waste.

[0004] Goaf filling can ensure the safety of mining production and increase the stability of stope surrounding rock, but the cost of filling material and the problem of filling slurry transportation are the constraints of its technology development, and it is of great significance to fully utilize coal gangue produced in coal mining and red mud produced in aluminum smelting to prepare filling material that meets the relevant performance and economic benefits.

[0005] Full consideration is given to the alkaline characteristics of red mud, and the red mud is used to reduce the amount of cement while absorbing CO2 through the alkaline characteristics of red mud, which is expected to achieve net zero emission of carbon and even negative emission for coal and aluminum enterprises. SUMMARY

[0006] To solve the series of problems caused by the stacking of red mud and coal gangue, the present application aims to provide a kind of carbon fixation filling method based on coal-aluminum paragenetic deposit synchronous exploitation.

[0007] In the present application, based on the synchronous safe and efficient exploitation of coal-aluminum paragenetic deposit, a green and safe and efficient coal-aluminum paragenetic deposit synchronous exploitation filling method is provided, which can not only utilize two kinds of bulk solid waste, red mud and coal gangue, but also can safely and efficiently exploit the upper aluminum ore and lower coal mine through synchronous filling.

[0008] The present application provides a kind of carbon fixation filling method based on coal-aluminum paragenetic deposit synchronous exploitation, including the following process steps:

[0009] S1, coal-aluminum synchronous exploitation: synchronous exploitation of aluminum mine located in the lower layer and coal mine located in the upper layer, wherein the exploited aluminum mine is subjected to Bayer process to obtain Bayer red mud, and the exploited coal mine is subjected to coal separation and washing to obtain coal gangue;

[0010] S2, coal gangue treatment: crushing and screening the separated coal gangue to meet the requirements of filling aggregate in particle size;

[0011] S3, carbon sequestration and alkali removal treatment of red mud: CO2 gas with a purity of more than 99% is introduced into the bayer process red mud to remove alkali and meet the requirements of the filling material;

[0012] S4, the treated solid waste and cement are mixed according to the optimal ratio of red mud: coal gangue: cement = 4:2:4, water is added to adjust the solid-liquid ratio to 0.8, and the uniaxial compressive strength is 7.8 MPa and the slump is 13 cm.

[0013] S5, the filling material is pumped to the coal mine and aluminum mine goaf through a pipeline pumping system for filling.

[0014] Further, in S1, the upper coal seam and the lower aluminum mine layer are simultaneously mined under the condition of meeting the safety production and relevant standards, and the coal and aluminum mine enterprise has the condition of smelting aluminum nearby, so as to facilitate the further treatment and transportation of the obtained bayer process red mud, and at the same time, the coal has the condition of nearby sorting, which also facilitates the further treatment and transportation of the coal gangue.

[0015] Further, in S2, the coal gangue is crushed and sorted into particles with a particle size of less than 20 mm, and the mass fraction of particles with a particle size of less than 5 mm is 30% to 50%.

[0016] Further, in S3, the CO2 gas is introduced into the red mud for alkali removal treatment, and through the acid-base neutralization reaction, the pH value of the bayer process red mud is reduced to the range of 6.5 to 8.5, meeting the pH value requirement of red mud landfill.

[0017] Further, in S4, the treated coal gangue and treated red mud are mixed, and cement is added according to the optimal ratio of red mud: coal gangue: cement = 4:2:4, water is added to adjust the solid-liquid ratio to 0.8, and the uniaxial compressive strength is 7.8 MPa and the slump is 13 cm.

[0018] Further, in S5, the pipeline pumping system selects a steel pipe with a pipe diameter of 20 cm for slurry filling, and the pumping pressure is 1.5 MPa, and the filling material is pumped to the coal mine and aluminum mine goaf for carbon sequestration and filling; the specific filling method is complete filling until the goaf is compacted, and the bulk density of the compacted filling body is about 2 g / cm 3 , the actual uniaxial compressive strength is more than 7.0 MPa, the filling roof ratio is more than 90%, and the roof subsidence is relieved by more than 85%.

[0019] In the above method, a coal gangue crushing workshop, a red mud carbon fixation and alkali removal workshop and a filling slurry preparation workshop are arranged on the ground above the ore deposit, the sorted coal gangue is transported to the coal gangue crushing workshop for crushing, the Bayer process red mud is transported to the red mud carbon fixation and alkali removal workshop for alkali removal treatment, then the crushed coal gangue and the alkali removed red mud are mixed in the filling slurry preparation workshop to prepare filling materials by adding cement and water; a pipeline system is arranged in the filling drilling, a coal seam goaf filling pipeline and an aluminum ore layer goaf filling pipeline are arranged, the pipeline system extends from the ground filling pump station to the coal seam and aluminum ore layer goaf, a steel pipe with a pipe diameter of 20 cm is selected for slurry filling, the pumping pressure is 1.5 MPa, the filling materials are transported through the coal seam goaf filling pipeline to fill the upper coal seam goaf, and the filling materials are transported through the aluminum ore layer goaf filling pipeline to fill the lower aluminum ore layer goaf.

[0020] The beneficial effects of the present application are as follows:

[0021] (1) The present application synchronously fills the goafs of the coal mine and the aluminum mine, thereby ensuring safe and efficient synchronous mining of the coal-aluminum coexisting ore deposit.

[0022] (2) The present application fully utilizes the two solid wastes of red mud generated in the aluminum smelting process and coal gangue generated in the coal washing process, thereby reducing the environmental pollution and safety problems caused by the accumulation of red mud and coal gangue.

[0023] (3) In the present application, CO2 is introduced into the red mud during the treatment process to remove alkali from the red mud, thereby not only making the pH value of the red mud meet the landfill requirements, but also permanently sealing CO2 in the underground by using the red mud as a cementing material. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a schematic diagram for synchronous mining and carbon fixation of a coal-aluminum coexisting ore deposit;

[0025] Figure 2 It is a schematic diagram of coal-aluminum ore layer position of a coal-aluminum coexisting ore deposit;

[0026] Figure 3 It is a schematic diagram of the effect of synchronous mining and carbon fixation of a coal-aluminum coexisting ore deposit;

[0027] Figure 4 It is a flow chart of synchronous mining and carbon fixation of a coal-aluminum coexisting ore deposit;

[0028] In the figure: 1-coal seam; 2-aluminum ore layer; 3-coal gangue crushing workshop; 4-red mud carbon fixation and alkali removal workshop; 5-filling slurry preparation workshop; 6-filling drilling; 7-coal seam goaf filling pipeline; 8-aluminum ore layer goaf filling pipeline; 9-filling body; 10-coal preparation plant; 11-aluminum smelting plant. DETAILED DESCRIPTION

[0029] The present application will be further illustrated by the following examples, but is not limited to the following examples.

[0030] The present application provides a carbon fixation filling method based on synchronous mining of coal-aluminum paragenetic deposit, comprising the following process steps:

[0031] S1, synchronous mining of coal and aluminum: synchronous mining of aluminum ore located in the lower layer and coal mine located in the upper layer, wherein the mined aluminum ore is subjected to Bayer process to obtain Bayer red mud, and the mined coal mine is subjected to separation and coal washing to obtain coal gangue;

[0032] S2, coal gangue treatment: crushing and screening the separated coal gangue to meet the requirements of filling aggregate in particle size;

[0033] S3, red mud carbon fixation and alkali removal treatment: introducing CO2 gas with a purity of more than 99% into the Bayer red mud for alkali removal treatment to meet the requirements of filling material;

[0034] S4, adding cement to the two treated solid wastes, S4 is a mixture of treated coal gangue and treated red mud, adding cement, the optimal ratio of red mud: coal gangue: cement is 4:2:4, the solid-liquid ratio is adjusted to 0.8 by adding water, and the uniaxial compressive strength is 7.8 MPa and the slump is 13 cm;

[0035] S5, slurry filling is carried out by selecting a steel pipe with a pipe diameter of 20 cm for the pipeline pumping system, and the pumping pressure is 1.5 MPa, the filling material is pumped to the goaf of coal mine and aluminum mine for carbon fixation filling; the complete filling method is adopted until the goaf is compacted.

[0036] In the above method, a coal gangue crushing workshop 3, a red mud carbon fixation and alkali removal workshop 4, and a filling slurry preparation workshop 5 are arranged on the ground above the deposit, the separated coal gangue is transported to the coal gangue crushing workshop for crushing, the Bayer red mud is transported to the red mud carbon fixation and alkali removal workshop for alkali removal treatment, then the crushed coal gangue and the alkali-removed red mud are mixed in the filling slurry preparation workshop to prepare filling material by adding cement and water; a pipeline system is arranged in the filling drilling well 6, a coal seam goaf filling pipeline 7 and an aluminum mine goaf filling pipeline 8 are arranged, the pipeline system extends from the ground filling pump station to the coal seam and aluminum mine goaf, a steel pipe with a pipe diameter of 20 cm is selected for slurry filling, the pumping pressure is 1.5 MPa, the filling material is transported through the coal seam goaf filling pipeline to fill the goaf of the upper coal seam 1, and the filling material is transported through the aluminum mine goaf filling pipeline 8 to fill the goaf of the lower aluminum mine layer 2.

[0037] In order to have a clearer understanding of the technical objects, features and effects of the present application, the coal-aluminum paragenetic deposit synchronous mining carbon fixation filling method will be further described in detail in conjunction with the drawings.

[0038] A coal-aluminum joint venture located in Lvliang City, Shanxi Province, the coal seam and aluminum ore layer position relationship is shown in the figure 1, 2, the upper coal seam is 3m thick, nearly horizontal coal seam, and the lower nearly horizontal aluminum ore layer with a thickness of 2m is synchronously mined, the coal seam and aluminum ore layer interval is 50m. After the coal seam is mined, the coal is separated in the coal preparation plant 10 located in the surface industrial square to obtain coal gangue, and the bauxite is obtained after passing through the aluminum smelter 11 in the surface industrial square to obtain the Bayer red mud. The separated coal gangue is transported to the coal gangue crushing workshop 3, which is crushed to a particle size of less than 20mm, and the proportion of particles less than 5mm is 30%-50%. The treated coal gangue and treated red mud are mixed in the filling slurry preparation workshop 5, and cement is added. According to the mass ratio of red mud: coal gangue: cement = 4:2:4, the solid-liquid ratio is adjusted to 0.8 to prepare the filling material. The obtained filling material has a uniaxial compressive strength of 7.8MPa and a slump of 13mm. The pipe system is arranged in the filling well 6, which extends from the ground filling pump station to the coal mine aluminum ore layer goaf. A steel pipe with a pipe diameter of 20cm is selected for slurry filling, and the pumping pressure is 1.5MPa. 7 is the coal seam goaf filling pipe, which is used for filling the upper coal seam goaf, 8 is the aluminum ore layer goaf filling pipe, which is used for filling the lower aluminum ore layer goaf, and the goaf is filled as much as possible to form a dense filling body 9. The bulk density of the dense filling body is about 2g / cm 3 , the actual uniaxial compressive strength is 7.6MPa, the filling roof ratio is 90%, and the roof subsidence is relieved by more than 85%.

[0039] Through the carbon fixation and filling method based on the synchronous mining of coal-aluminum symbiotic deposit, the mining efficiency of the enterprise's coal-aluminum resources is improved by more than 20%, the enterprise saves about 2 million yuan of red mud and coal gangue solid waste treatment funds, and realizes the fixation of 30kg of CO2 per ton of red mud in the red mud dealkalization process. The problems of surface subsidence and groundwater resource damage caused by underground mining are solved.

Claims

1. A method for carbon sequestration and backfilling based on simultaneous mining of coal-aluminum symbiotic deposits, characterized in that... Includes the following steps: S1, Coal and Aluminum Simultaneous Mining: The aluminum ore in the lower layer and the coal ore in the upper layer are mined simultaneously. The mined aluminum ore is smelted into Bayer red mud through the Bayer process, and the mined coal is sorted and washed to obtain coal gangue. S2, Coal gangue processing: The sorted coal gangue is crushed and screened to make its particle size meet the requirements of backfill aggregate; S3, Red mud carbon fixation and dealkali treatment: CO2 gas with a purity of over 99% is introduced into Bayer process red mud to carry out dealkali treatment and meet the requirements of the backfill material; For the treatment of red mud, CO2 gas is introduced into the red mud to carry out dealkalization treatment. Through acid-base neutralization reaction, the pH value of Bayer process red mud is reduced to 6.5~8.5, which meets the pH value requirements for red mud landfill. S4. Add cement to the two types of treated solid waste, mix red mud: coal gangue: cement = 2~4: 2~4: 2~4, add water to adjust the solid-liquid ratio to 0.6~1.0 and mix to prepare filling material. The resulting filling material meets the requirements of uniaxial compressive strength of 2.5MPa~10MPa and slump greater than 10mm. S5, through a pipeline pumping system, pumps filling materials to the goaf areas of coal mines and aluminum mines for filling; a pipeline system is arranged in the same filling well, with filling pipelines for coal seam goaf areas and aluminum mine goaf areas. The pipeline system extends from the ground filling pumping station to the goaf areas of coal seam and aluminum mine. Filling materials are transported through the coal seam goaf filling pipeline to fill the upper coal seam goaf area, and at the same time, filling materials are transported through the aluminum mine goaf filling pipeline to fill the lower aluminum mine goaf area. The pipeline pumping system uses steel pipes with a diameter of 20cm for slurry filling, with a pumping pressure of 1.5MPa, to pump the filling material to the goaf areas of coal mines and aluminum mines for carbon sequestration filling.

2. The carbon sequestration and backfilling method based on simultaneous mining of coal-aluminum symbiotic deposits according to claim 1, characterized in that: S1 refers to the simultaneous mining of coal and aluminum, where the upper coal seam and the lower aluminum ore seam are mined simultaneously under the condition of meeting safety production and relevant standards. Coal and aluminum mining enterprises have the conditions for nearby aluminum ore smelting and nearby coal sorting, which facilitates the further processing and transportation of the resulting Bayer process red mud and coal gangue.

3. The carbon sequestration and backfilling method based on simultaneous mining of coal-aluminum symbiotic deposits according to claim 1, characterized in that: The coal gangue processing in S2 involves crushing and sorting the coal gangue into particles with a size of less than 20 mm and a mass ratio of less than 5 mm, which is 30% to 50%.

4. The carbon sequestration and backfilling method based on simultaneous mining of coal-aluminum symbiotic deposits according to claim 1, characterized in that: S4 is made from a mixture of treated coal gangue and treated red mud, with cement added. The optimal ratio of red mud:coal gangue:cement is 4:2:

4. Water is added to adjust the solid-liquid ratio to 0.8, and the uniaxial compressive strength is 7.8 MPa, with a slump of 13 cm.

5. The carbon sequestration and backfilling method based on simultaneous mining of coal-aluminum symbiotic deposits according to claim 1, characterized in that: The process involves complete filling until the goaf is compacted, with the compacted filling having a bulk density of 2 g / cm³. 3 The actual uniaxial compressive strength is above 7.0 MPa, the filling and roof connection rate is above 90%, and the reduction of roof subsidence is above 85%.

6. The carbon sequestration and backfilling method based on simultaneous mining of coal-aluminum symbiotic deposits according to claim 1, characterized in that: A coal gangue crushing workshop, a red mud carbon fixation and dealkali removal workshop, and a backfill slurry preparation workshop are set up on the ground above the mine. The sorted coal gangue is transported to the coal gangue crushing workshop for crushing, and the Bayer process red mud is transported to the red mud carbon fixation and dealkali removal workshop for dealkali treatment. Then, in the backfill slurry preparation workshop, the crushed coal gangue and the dealkali removed red mud are mixed, and cement and water are added to make backfill material.

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