A pre-buried underground alkali slag injection well filling salt cavern slurry mixing device and alkali slag injection well filling salt cavern method

Abstract

The invention discloses a pre-buried underground alkali slag injection well filling salt cavern slurry mixing device, wherein the slurry mixing pool is a vertical cylinder with half of the upper opening closed and half of the upper opening open, and an agitator is installed in the slurry mixing pool; a calcium liquid pipeline is connected to the calcium liquid storage tank, and one end of the calcium liquid pipeline extends to the upper opening of the cylinder; a salt cavern is an underground space formed by mining rock salt resources by a connecting well water solution method, two salt caverns are connected underground, and a slag injection well and a brine drainage well are respectively opened above the two salt caverns; the slurry mixing pool is connected to the slag injection well through a slurry filling pipeline, and the brine drainage well is connected to the brine storage tank through a brine drainage pipeline; a circular hole a is provided at the center of the bottom end cap of the slurry mixing pool, one end of the suction pipeline extends to the upper opening of the cylinder, and a filter screen a is provided at the upper outlet of the suction pipeline. The invention can greatly improve the efficiency of alkali slag injection well filling, improve the strength of the salt cavern goaf, reduce the intensity of on-site labor operations, and reduce the formation of scale on the inner wall of the pipeline, and has good social and economic benefits.

Description

Technical Field

[0001] The invention relates to the field of salt chemical production equipment, and in particular to a pre-buried underground alkali slag well-injection salt cavern filling slurry mixing device and an alkali slag well-injection salt cavern filling method. Background Art

[0002] In order to solve the problem of alkali slag solid waste disposal, researchers turned their attention to underground salt caverns. Most rock salt resources are mined by drilling and water-soluble mining, which has formed a large number of underground salt cavities. As the salt cavities continue to shrink, the rock salt roof will collapse and even cause surface subsidence. Therefore, how to inhibit the volume shrinkage of underground salt cavities and control surface subsidence has become an important direction for the comprehensive utilization of underground salt cavities. Applying filling mining technology to the management of underground salt cavity goaf areas can not only solve this problem well, but also solve the problem of alkali slag solid waste disposal. In recent years, the technology of using salt cavity filling to treat alkali slag has developed rapidly. Alkali slag well filling has effectively suppressed the problem of ground subsidence in salt cavern goaf areas, with significant social and economic benefits.

[0003] Patent CN111069221A alkali slag filling salt cavern system provides a method for filling salt caverns with alkali slag. However, this alkali slag filling salt cavern system currently has some serious problems in the production site: first, the sand particles in the alkali slag cause serious wear on the grouting pipe, and the pipe needs to be replaced frequently during production; second, the insoluble substances in the alkali slag adhere to the pipe and form scale, causing the pipe to be blocked, and regular water injection and flushing are required. Third, the alkali slag accumulation mining area occupies land resources. The previous slurry mixing device was located on the ground, and the slurry mixing operation was intensive, and the equipment maintenance and labor costs were high.

[0004] The above problems seriously restrict the development of alkali slag injection well filling technology. For this reason, the present invention provides a pre-buried underground alkali slag injection well filling salt cavern slurry mixing device, which can effectively solve the above problems and improve the efficiency of alkali slag injection well filling salt caverns. Summary of the invention

[0005] The present invention aims to provide a pre-buried underground alkali slag well-injection salt cavern filling slurry mixing device and an alkali slag well-injection salt cavern filling method, which can greatly improve the alkali slag well-injection filling efficiency, improve the strength of the filling body in the salt cavern goaf, effectively solve the problem of alkali slag ground stacking, reduce the intensity of on-site labor operations, solve the problem of sand particles in the alkali slag wearing the slurry filling pipeline, and reduce the formation of scale on the inner wall of the pipeline, which has good social and economic benefits.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A pre-buried underground alkali slag injection well filling salt cavern slurry mixing device comprises a slurry mixing pool, a calcium liquid storage tank, a brine storage tank, a slag injection well, a brine drainage well and a salt cavern; the slurry mixing pool is vertical, the upper cylinder is cylindrical, the bottom head is ellipsoidal, the slurry mixing pool is pre-buried underground, the upper opening of the cylinder is half closed and half open, and an agitator is installed in the slurry mixing pool.

[0008] The calcium liquid storage tank is connected with a calcium liquid pipeline, one end of which extends above the open portion of the upper opening of the cylinder body, and the calcium liquid pipeline is connected with a first valve.

[0009] The salt caverns are formed by mining rock salt resources using the water-soluble method using connected wells. The two salt caverns are connected underground, and the distance between the two salt caverns is about 200 to 400 meters.

[0010] The volume of salt caverns continues to increase during the production process, and the exploitation of rock salt resources is approaching the end of its mining life. At this time, insoluble sediment accumulates at the bottom of the salt cavern, and the upper part is filled with saturated brine. The salt cavern has no connection with other salt caverns in series.

[0011] The average NaCl grade of the salt group in the target salt cavern is 53.09%, the average expansion rate of water-insoluble matter is 17%, the brine concentration is 24°Bé, the specific gravity is 1.2, and the main components of the brine in the salt cavern are NaCl 290-305g / L and Na2SO4 20-30g / L.

[0012] The slag injection well and the brine discharge well are respectively opened above the two salt caverns; the slurry adjusting pool is connected to the slag injection well through a slurry filling pipeline, the slurry filling pipeline is connected to a second valve, the brine discharge well is connected to the brine storage tank through a brine discharge pipeline, the brine discharge pipeline is connected to a third valve; there is a circular hole a at the center of the bottom head of the slurry adjusting pool, a suction pipeline is connected to the circular hole a, the suction pipeline is connected to a fourth valve, one end of the suction pipeline extends to above the open part of the upper opening of the cylinder, and a filter screen a is provided at the outlet above the suction pipeline, and the filter screen a is detachable.

[0013] A further solution of the present invention is that the upper cylinder of the slurry mixing tank is about 30 to 50 mm above the ground, the inner diameter of the slurry mixing tank cylinder is D=3 to 5 m, the upper cylinder height is H=6 to 8 m, the bottom height of the bottom head ellipsoid is h=1.1 to 1.8 m, and the wall thickness of the slurry mixing tank is 8 to 15 mm; two spliced ​​steel guide plates open to the feed inlet are welded at the junction of the closed part and the open part of the slurry mixing tank, and the two guide plates are both rectangular, the lower guide plate is inclined, the inclination is 40 to 60°, and the upper guide plate is vertical; vertical baffles are evenly arranged around the cylinder of the slurry mixing tank, the width of the baffle is 0.1 to 0.5 times the inner diameter of the slurry mixing tank cylinder, the upper part of the baffle is 0.1 to 0.6 m away from the mouth of the slurry mixing tank, and the lower part is 1.2 to 2.0 m away from the bottom end of the bottom head, and the number of baffles is 4 to 6.

[0014] A further solution of the present invention is that the diameter of the circular hole a is 40-60 mm, the inner diameter of the suction pipe is 60-80 mm, the suction pipe directly reaches the vertical material guide plate above the closed top of the slurry mixing tank, and the suction pump is arranged above the closed top of the slurry mixing tank; a rubber hose is connected to the outlet of the suction pipe, the hose is suspended on the vertical material guide plate, a fourth valve is provided at the pipe mouth of the suction pipe, the fourth valve is located between the filter screen a and the rubber tube, the fourth valve is opened, the suction pump is turned on, the filter residue and slurry enter the suction pipe, the slurry re-enters the slurry mixing tank through the rubber tube, the filter residue remains at the filter screen a at the pipe mouth, and personnel are regularly arranged to clean it. The aperture of the filter screen a is 1.25-2.5 mm.

[0015] A further solution of the present invention is that the agitator is a double-layer six-blade oblique paddle agitator, the agitator includes a stirring shaft, an impeller assembly and a transmission device, the stirring shaft is fixedly installed at the top center of the slurry mixing tank, the impeller is double-layered, each layer has 6 blades, the angle between the blades and the movement direction is -30 to 60°, preferably 30 to 60°; the blade diameter is 1.5 to 2.5m, the double-layer impeller spacing is 2 to 3m, and the pitch to blade diameter ratio is 0.7 to 0.9; the transmission device includes a motor, a reducer, a coupling, a frame and a base installed and fixed above the closed top of the slurry mixing tank.

[0016] A further solution of the present invention is that a circular hole b is provided at the side wall of the slurry mixing tank between the double-layer paddles of the agitator, the circular hole b is located between the baffles of the slurry mixing tank, and the aperture of the circular hole b is 150-250 mm, preferably 200-250 mm; a filter screen b is provided at the mouth of the circular hole b, and the aperture of the filter screen b is 0.5-1.25 mm, preferably 0.5-1 mm; the circular hole b is connected to the slurry filling pipeline, the diameter of the slurry filling pipeline is 170-220 mm, a second valve is installed on the slurry filling pipeline, and the slurry is pumped to the underground target salt cavern through the slurry filling pipeline; the cylinder, head, agitator, guide plate and baffle of the slurry mixing tank are all made of stainless steel, and the filter screen a and the filter screen b are made of carbon steel.

[0017] A further solution of the present invention is that the technical casing diameter of the slag injection well and the brine drainage well is 139.7mm, 177.8mm or 244.5mm, and the diameters of the slurry filling pipeline, calcium liquid pipeline and brine drainage pipeline on the ground are 150-250mm; flow meters and pressure gauges are installed at the wellheads of the slag injection well and the brine drainage well to record the injection and drainage brine flow and the wellhead pressure.

[0018] A further solution of the present invention is that each valve should be corrosion-resistant, wear-resistant and leak-proof, and valves installed outdoors should have all-weather protection capabilities.

[0019] A method for filling a salt cavern with alkali slag by injecting alkali slag into a well, using the above-mentioned pre-buried underground alkali slag injection well filling salt cavern slurry mixing device, comprising the following steps:

[0020] S1. Open the first valve on the calcium liquid pipeline, transport the calcium liquid in the calcium liquid storage tank to the slurry mixing tank, inject the calcium liquid until the liquid level in the slurry mixing tank reaches 1 / 2 of the double-layer impeller, close the first valve, and turn on the agitator.

[0021] S2. The slag truck dumps the pre-treated alkali slag into the slurry mixing tank, and continues to inject calcium liquid according to the ratio. The liquid level in the slurry mixing tank should be higher than the agitator blades and not higher than the top of the cylinder.

[0022] S3. After the slurry is fully stirred, the second valve on the slurry filling pipeline is opened to transport the prepared slurry to the target salt cavern.

[0023] S4. The slurry injected into the underground salt cavern flocculates and settles in the salt cavity to form a filling body with a certain strength. At the same time, the saturated brine in the salt cavern is driven out from the brine discharge pipeline into the brine storage tank on the ground for processing and production.

[0024] S5. Repeat the above steps until the target salt cavern is completely filled and seal the salt cavern.

[0025] A further solution of the present invention is that in S2, the pretreatment refers to the alkali slag including sand removal, clarification, and filter pressing processes, and the concentration of the alkali slag after the pretreatment is above 40%, and is mainly powder particles.

[0026] A further solution of the present invention is that in S3, alkali slag and calcium liquid are prepared into slurry according to a certain ratio, and the slurry concentration is 15% to 40%, preferably 20% to 30%; the grouting flow rate of the slag injection well is 100 to 250 cubic meters / h, preferably 150 to 250 cubic meters / h, and the excess slurry in the slurry adjustment pool can be transported to other mining areas through a slurry filling pipeline.

[0027] The filling system supporting the device mainly consists of four parts: waste liquid collection station, slurry preparation station, ground grouting station and underground salt cavern. Alkali slag and calcium liquid are produced at the waste liquid collection station. There is a slurry mixing pool in the slurry preparation station. The slurry mixing pool is equipped with an agitator and a suction pipe. The ground grouting station controls the second valve to transport the prepared slurry to the target underground salt cavern through the slurry filling pipe. The underground salt cavern is equipped with pipes for slag injection wells and brine discharge wells.

[0028] The waste liquid collection station is located in the alkali plant near the mining area. The alkali plant uses the ammonia-alkali process to produce sodium carbonate and calcium chloride. Every ton of soda ash produced will generate 10m 3 The waste liquid is about 1000 tons, of which the alkali slag and calcium liquid solid waste slag account for about 3%. At present, the alkali slag is piled in the open air at the waste liquid collection station in the alkali plant. The pre-treated alkali slag is transported to the slurry preparation center in the target mining area by slag trucks. The calcium liquid is transported to the calcium liquid storage tank in the target mining area through pipelines and directly participates in the slurry preparation, effectively avoiding the problem of alkali slag stacking and occupying land in the mining area.

[0029] The main components of alkali slag are CaCO3, CaSO4·0.5H2O, and SiO2. The alkali slag particles are mainly powder particles of 5 to 75μm, accounting for about 80%, and the temperature is 80 to 90℃.

[0030] Calcium solution is the ammonia-alkali waste liquid produced in the production process of soda ash. The components of calcium solution are generally CaCl2 and NaCl. The CaCl2 content is 90-120g / L, preferably 100-120g / L, and the NaCl content is 40-60g / L.

[0031] Beneficial effects of the present invention:

[0032] The pre-buried underground alkali slag injection well filling salt cavern slurry mixing device of the present invention adopts multi-level filtration treatment in the slurry mixing tank, which solves the problem of a large amount of insoluble particles in the alkali slag filling causing pipe wear and reduces the cost of frequent pipe replacement. By reasonably setting the parameters of the stirring device and optimizing the slurry mixing process, a slurry with better flow performance is configured, which accelerates the diffusion and flocculation filling progress of the slurry entering the salt cavern.

[0033] The pre-buried underground alkali slag well filling salt cave slurry mixing device of the present invention solves the problem of alkali slag disposal, reduces the intensity of on-site operations, and improves the efficiency of alkali slag well filling. After alkali slag well filling, the strength of the salt cave goaf can be greatly improved, and geological disasters such as goaf settlement and salt cave shrinkage can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is an overall schematic diagram of the pre-buried underground alkali slag injection well filling salt cavern slurry mixing device of the present invention.

[0035] Figure 2 It is a top view of the middle slurry mixing tank of the present invention.

[0036] In the figure: 1-slurry mixing tank, 2-baffle, 3-agitator, 4-insoluble matter on the bottom of the tank, 5-paddle, 6-slurry filling pipeline, 7-suction pipeline, 8-brine discharge well salt cavern dissolution cavity, 9-slag injection well salt cavern dissolution cavity, 10-brine discharge well, 11-slag injection well, 12-insoluble matter sediment in the dissolution cavity, 13-third valve, 14-second valve, 15-brine discharge pipeline, 16-brine storage tank, 17-calcium liquid storage tank, 18-fourth valve, 19-first valve, 20-calcium liquid pipeline. DETAILED DESCRIPTION

[0037] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0038] The embodiments of the present invention are mainly aimed at the goaf formed by water-soluble mining of salt rock resources, namely, salt caverns. In view of the characteristics of many interlayers and thin salt layers of salt rock resources, the connected well water-soluble mining method is generally used for operation, that is, fresh water is injected into the salt layer through the casing to dissolve the rock salt resources to form brine discharge, and finally form a salt cavern goaf in the underground salt layer. According to the geological data of the target mining area and the ore dissolution test, the average NaCl grade of the salt group is 53.09%, the average expansion rate of water insoluble matter is 17%, the brine concentration is 24°Bé, the specific gravity is 1.2, and the main components of the brine in the salt cavern are NaCl290~305g / L and Na2SO420~30g / L.

[0039] The alkali slag produced by the ammonia-soda process of the alkali plant is stored in the alkali slag collection station, and the produced calcium liquid is stored in the calcium liquid storage tank 17. The pre-treated alkali slag is transported to the target mining area by a slag transport vehicle. The distance between the alkali plant and the mining area is about 4 to 6 km. Open the first valve 19, and transport the calcium liquid in the calcium liquid storage tank 17 to the slurry mixing tank 1 through the calcium liquid pipeline 20. When the liquid level in the slurry mixing tank 1 reaches the middle of the double-layer impeller, close the first valve 19. The alkali slag is transported to the target mining area and directly dumped into the slurry mixing tank 1. At the same time, open the first valve 19, turn on the agitator 3, and control the amount of calcium liquid injected into the slurry mixing tank 1 according to a certain ratio based on the amount of alkali slag injected into the slurry mixing tank 1. Control the liquid level in the slurry mixing tank 1 to be higher than the blade 5 above the agitator 3 and not higher than the top of the cylinder. After the calcium solution and the alkali residue are mixed and stirred evenly, the second valve 14 at the wellhead of the slag injection well 11 is opened, and the slurry enters the slurry filling pipeline 6 through the screen b, and enters the slag injection well 11, and finally enters the salt cavern cavity 9 of the slag injection well, and the slurry is accumulated on the insoluble sediment 12 of the cavity, and the slurry is slowly flocculated and formed in the salt cavern cavity 9 of the slag injection well and the salt cavern cavity 8 of the brine discharge well to form a filling body with a certain strength, and the excess water and brine in the salt cavern are discharged to the ground through the brine discharge well 10 and enter the brine storage tank 16. As the alkali residue filling operation continues, the insoluble matter 4 at the bottom of the slurry mixing pool 1 continues to accumulate, affecting the operating efficiency of the slurry mixing pool 1. At this time, the fourth valve 18 is opened, and the insoluble matter 4 at the bottom of the pool is piled at the fourth valve 18 at the pipe mouth of the suction pipe 7 through the filter residue pipe, and the slurry enters the slurry mixing pool 1, and the filter residue is left at the filter screen at the pipe mouth, and personnel are regularly arranged to clean it.

[0040] As the filling operation is in progress, the slurry is continuously injected into the salt cavern cavity 9 of the slag injection well. The inner wall of the casing of the slag injection well 11 of the salt cavern is prone to scaling. Therefore, according to the actual production needs, it is necessary to arrange well inversion regularly. The well inversion means that the slag injection well 11 is used as a brine drainage well, and the brine drainage well 10 is used as a slag injection well, and the operations are alternating. Generally, the mine production site needs to arrange well inversion every 3 months, depending on the actual production situation.

[0041] During the slag injection process, if the scale of the slag injection well 11 pipeline is serious and even causes pipeline blockage, it is necessary to carry out well cleaning operations. When cleaning the well, the lowering speed of the well cleaning gauge should be less than 10-20m / min. When the well cleaning gauge is lowered to 100m from the casing mouth, the lowering speed shall not exceed 5-10m / min. After the well cleaning gauge is lowered to the scaling area on the sand surface, it is lifted up to 2m above the sand surface for sufficient well washing and sand flushing. When lifting the well cleaning drill string, the pipe lifting speed is 10-13m / min, and the maximum load shall not exceed the safety load of the oil pipe.

[0042] Before injecting alkali slag into the salt cavern, it is necessary to use sonar to measure the bottom depth, top position and volume of the salt cavern, and compare the previous drilling data to obtain the net volume of the salt cavern. As the alkali slag filling operation continues, the filling surface in the underground salt cavern continues to rise and gradually approaches the casing. In order to ensure the smooth filling, it is necessary to arrange pipe cutting operations regularly. The pipe cutting is based on the production data of the well group and the cavity measurement data. According to the production data of the mining area, for every 1m³ of salt cavern volume formed, about 12.7m³ of brine is extracted, and 1t of alkali slag is used to fill about 0.94m³ of the salt cavern, that is, 1m³ of salt cavern contains about 1.06t of alkali slag. Based on this, the amount of slag injected into the salt cavern can be simply calculated.

[0043] When the filling operation of two underground salt caverns is close to the casing mouth, cement slurry is injected to form a hard cement stone column in the production technical casing to resist the creep of the formation rock, enhance the stability of the rock, protect the aquifer in the overlying loose formation from the contamination of formation fluid or surface water, and isolate the exploited well section from the unexploited well section. The sealing operation is to place a permanent bridge plug in the technical casing to create an artificial well bottom to block the mutual flow of brine in the underground salt cavern and fluid in the technical casing. The location of the bridge plug should be selected close to the casing mouth to ensure the sealing effect. In addition, water should be injected into the casing before placing the bridge plug, preferably after the water returns to the wellhead, to ensure that the salt cavern is under pressure after the bridge is erected. Then the pipe is forged and milled, and finally the hole is grouting and sealing. The amount of cement used for sealing the well is calculated according to the volume of the wellbore, and the cement slurry is injected and sealed with a mud pump and drill pipe. Grouting is performed from the bridge plug position to the wellhead. The bridge plug position can be selected from the casing deformation point and the top of the cavity. Example

[0044] A pre-buried underground alkali slag injection well filling salt cave slurry mixing device, the device is applied to the connected well embodiment as follows:

[0045] The target mining area is located in a salt mine in Huai'an, Jiangsu Province. There are 9 production well groups and 18 salt wells in total. The approved mine production scale is 1.2 million tons / year, and the mining elevation is -1030~-1700m. The salt mine has been in mining and production for more than 15 years. The brine production is mainly based on directional connected well technology. The production time is long. According to production estimates, the volume of underground dissolution cavity is relatively large.

[0046] A group of salt wells A1-A2 was selected for in-depth work and systematic evaluation. First, the production situation of this group of salt wells was investigated. The well spacing of A1-A2 well group was 230m, the production-injection ratio was stable at about 0.9, and the depth of the aquifer was about 300m.

[0047] According to sonar measurements, the bottom depth of the A1 well is -1152.3m, the top of the well is -1105.6m, the safe mining depth is -1030m, and the measured volume is 274,000 cubic meters. The bottom depth of the A2 well is -1147.3m, the top of the well is -1130m, and the measured volume is 181,000 cubic meters.

[0048] The slurry mixing device and some system parameters in production are as follows:

[0049] The upper cylinder of the slurry mixing tank 1 is 40mm above the ground, with an internal diameter of 4m, a height of 6m, a height of 1.5m for the ellipsoidal body of the bottom head, a wall thickness of 10mm for the slurry mixing tank 1, a material guide plate welded at the junction of the closed part and the open part of the slurry mixing tank 1 with an inclination of 45°, a circular hole with a diameter of 50mm at the center of the bottom head of the slurry mixing tank 1, an inner diameter of the suction pipe 7 of 60mm, a filter mesh aperture of 1.25mm at the outlet above the suction pipe 7, and a stirrer 3 for stirring. The angle of the blade 5 of the device 3 is 30°, the diameter of the blade 5 is 1.5m, the distance between the double-layer impeller is 2m, the number of vertical baffles 2 on the wall of the slurry adjustment pool 1 is 4, the width of a single baffle 2 is 0.8m, the lower part of the baffle 2 is 1.6m away from the bottom end of the bottom head, the diameter of the circular holes on the pool wall between the baffles 2 is 200mm, the diameter of the filter screen at the circular hole mouth is 0.5mm, the diameter of the filling slurry pipeline is 170mm, the slurry concentration is 15%, and the grouting flow rate of the slag injection well 10 is 150 cubic meters / h.

[0050] The process of filling the A1-A2 well group with the alkali slag slurry mixing device is as follows:

[0051] Open the first valve 19, and transport the calcium liquid in the calcium liquid storage tank 17 to the slurry mixing tank 1 through the calcium liquid pipeline 20. When the liquid level in the slurry mixing tank 1 reaches the middle of the double-layer paddle 5, close the calcium first valve 19. The alkali slag is transported to the target mining area and directly dumped into the alkali slag slurry mixing tank 1. At the same time, open the first valve 19 and turn on the agitator 3. According to the amount of alkali slag injected into the slurry mixing tank 1, control the amount of calcium liquid injected into the slurry mixing tank 1 according to a certain ratio. Control the liquid level in the slurry mixing tank 1 to be higher than the paddle 5 above the agitator 3 and not higher than the top of the cylinder. After the calcium solution and the alkali slag are mixed and stirred evenly, the second valve 14 at the wellhead of the slag injection well 11 (A1) is opened, and the third valve 13 at the wellhead of the brine drainage well 10 (A2) is opened. The slurry passes through the screen b and enters the slurry filling pipeline 6, the slag injection well 11 (A1), and finally enters the salt cavern 9 of the slag injection well. The slurry accumulates on the insoluble sediment 12 of the cavity. The slurry slowly flocculates and forms in the salt cavern 9 of the slag injection well and the salt cavern 8 of the brine drainage well to form a filling body with a certain strength. The excess water and brine in the salt cavern are discharged to the ground through the brine drainage well 10 (A2) and enter the brine storage tank 16. When the A1 well is filled, the A2 well is used as the slag injection well and the A1 well is used as the brine drainage well. The above steps are repeated. When the A2 well is filled, the A1-A2 well group is sealed.

[0052] According to the data collected during production, a total of 297,000 cubic meters of alkali slag was injected into Well A1 during the five years, with an average annual injection of 59,400 cubic meters of alkali slag. A total of 204,000 cubic meters of alkali slag was injected into Well A2 during the five years, with an average annual injection of 40,800 cubic meters of alkali slag. The well has been sealed. Example

[0053] A pre-buried underground alkali slag injection well filling salt cave slurry mixing device, the device is applied to the connected well embodiment as follows:

[0054] The target mining area is located in a salt mine in Huai'an, Jiangsu Province. There are 8 salt wells in 9 production well groups. The approved mine production scale is 1.2 million tons / year. The mining elevation is -1030~-1700m. The salt mine has been in mining and production for more than 15 years. The brine production is mainly based on directional connected well technology. The production time is long. According to production estimates, the volume of underground dissolution cavity is relatively large.

[0055] A group of salt wells B1-B2 was selected for in-depth work and systematic evaluation. First, the production situation of this group of salt wells was investigated. The well spacing of B1-B2 well group was 352m, the production-injection ratio was stable at about 0.9, and the depth of the aquifer was about 300m.

[0056] According to sonar measurements, the B1 well has a bottom depth of -1162m, a top position of -1130m, a safe mining depth of -1030m, and a measured volume of 223,000 cubic meters. The B2 well has a bottom depth of -1325m, a top position of -1289m, and a measured volume of 227,000 cubic meters.

[0057] The slurry mixing device and some system parameters in production are as follows:

[0058] The upper cylinder of the slurry mixing tank 1 is 40mm above the ground, with an internal diameter of 4m, a height of 6m, a height of 1.5m for the ellipsoidal body of the bottom head, a wall thickness of 10mm for the slurry mixing tank 1, a material guide plate welded at the junction of the closed part and the open part of the slurry mixing tank 1 with an inclination of 45°, a circular hole with a diameter of 50mm at the center of the bottom head of the slurry mixing tank 1, an inner diameter of the suction pipe 7 of 60mm, a filter mesh aperture of 1.25mm at the outlet above the suction pipe 7, and a stirrer 3. The angle of the blade 5 is 30°, the diameter of the blade 5 is 1.5m, the distance between the double-layer impellers is 2m, the number of vertical baffles 2 on the wall of the slurry adjustment pool 1 is 4, the width of a single baffle 2 is 0.8m, the lower part of the baffle 2 is 1.6m away from the bottom end of the bottom head, the diameter of the circular holes on the pool wall between the baffles 2 is 200mm, the diameter of the filter screen at the circular hole mouth is 0.5mm, the diameter of the filling slurry pipeline is 170mm, the slurry concentration is 30%, and the grouting flow rate of the slag injection well 10 is 150 cubic meters / h.

[0059] The process of filling the B1-B2 well group with the alkali slag slurry mixing device is as follows:

[0060] Open the first valve 19, and transport the calcium liquid in the calcium liquid storage tank 17 to the slurry mixing tank 1 through the calcium liquid pipeline 20. When the liquid level in the slurry mixing tank 1 reaches the middle of the double-layer paddle 5, close the first valve 19. The alkali slag is transported to the target mining area and directly dumped into the alkali slag slurry mixing tank 1. At the same time, open the first valve 19 and turn on the agitator 3. According to the amount of alkali slag injected into the slurry mixing tank 1, control the amount of calcium liquid injected into the slurry mixing tank 1 according to a certain ratio. Control the liquid level in the slurry mixing tank 1 to be higher than the paddle 5 above the agitator 3 and not higher than the top of the cylinder. After the calcium liquid and the alkali slag are mixed and stirred thoroughly, the second valve 14 at the wellhead of the slag injection well 11 (B1) is opened, and the third valve 13 at the wellhead of the brine discharge well 10 (B2) is opened. The slurry passes through the screen b and enters the slurry filling pipeline 6, enters the slag injection well 11 (B1), and finally enters the salt cavern dissolving cavity 9 of the slag injection well. The slurry accumulates on the insoluble sediment 12 in the dissolving cavity. The slurry slowly flocculates and forms in the salt cavern dissolving cavity 9 of the slag injection well and the salt cavern dissolving cavity 8 of the brine discharge well to form a filling body with a certain strength. The excess water and brine in the salt cavern are discharged to the ground through the brine discharge well 10 (B2) and enter the brine storage tank 16. When the amount of alkali slag injected into Well B1 reaches 225,000 cubic meters, Well B2 is used as a slag injection well and B1 is used as a brine drainage well, and the above steps are repeated. When Well B2 is filled, Well B1 is used as a slag injection well and B2 is used as a brine drainage well, and the above steps are repeated until Well B1 is filled, and the B1-B2 well group is sealed.

[0061] According to the data collected during production, a total of 249,000 cubic meters of alkaline slag was injected into the B1 well over the past 6 years, with an average annual injection of 41,500 cubic meters. A total of 241,000 cubic meters of slag was injected into the B2 well over the past 4 years, with an average annual injection of 60,000 cubic meters. The well has been sealed. Example

[0062] A pre-buried underground alkali slag injection well filling salt cave slurry mixing device, the device is applied to the connected well embodiment as follows:

[0063] The target mining area is located in a salt mine in Huai'an, Jiangsu Province. There are 8 salt wells in 9 production well groups. The approved mine production scale is 1.2 million tons / year. The mining elevation is -1030~-1700m. The salt mine has been in mining and production for more than 15 years. The brine production is mainly based on directional connected well technology. The production time is long. According to production estimates, the volume of underground dissolution cavity is relatively large.

[0064] A group of salt wells was selected for in-depth work and systematic evaluation. First, the production situation of this group of salt wells was investigated. The well spacing of C1-C2 well group was 326m, the production-injection ratio was stable at about 0.9, and the depth of the aquifer was about 300m.

[0065] According to sonar measurements, the bottom depth of the C1 well is -1132m, the top position is -1109m, the safe mining depth is -1030m, and the measured volume is 187,000 cubic meters. The bottom depth of the C2 well is -1163.1m, the top position is -1113.5m, and the measured volume is 382,000 cubic meters.

[0066] The slurry mixing device and some system parameters in production are as follows:

[0067] The upper cylinder of the slurry mixing tank 1 is 40mm above the ground, with an internal diameter of 5m, an upper cylinder height of 8m, a bottom head ellipsoid height of 1.8m, a wall thickness of 15mm, a guide plate welded at the junction of the closed part and the open part of the slurry mixing tank 1 with an inclination of 45°, a circular hole with a diameter of 60mm at the center of the bottom head of the slurry mixing tank 1, an inner diameter of the suction pipe 7 of 80mm, a filter mesh aperture of 1.5mm at the outlet above the suction pipe 7, and a stirrer 3. The angle of the blade 5 is 45°, the diameter of the blade 5 is 2.5m, the distance between the double-layer impellers is 3m, the number of vertical baffles 2 on the wall of the slurry adjustment pool 1 is 6, the width of a single baffle 2 is 2.5m, the lower part of the baffle 2 is 2m away from the bottom end of the bottom head, the diameter of the circular holes on the pool wall between the baffles 2 is 250mm, the diameter of the filter screen at the circular hole mouth is 0.75mm, the diameter of the filling slurry pipeline is 220mm, the slurry concentration is 20%, and the grouting flow rate of the slag injection well 10 is 200 cubic meters / h.

[0068] The process of filling the C1-C2 well group with the alkali slag slurry mixing device is as follows:

[0069] Open the first valve 19, and transport the calcium liquid in the calcium liquid storage tank 17 to the slurry mixing tank 1 through the calcium liquid pipeline 20. When the liquid level in the slurry mixing tank 1 reaches the middle of the double-layer paddle 5, close the first valve 19. The alkali slag is transported to the target mining area and directly dumped into the alkali slag slurry mixing tank 1. At the same time, open the first valve 19 and turn on the agitator 3. According to the amount of alkali slag injected into the slurry mixing tank 1, control the amount of calcium liquid injected into the slurry mixing tank 1 according to a certain ratio. Control the liquid level in the slurry mixing tank 1 to be higher than the paddle 5 above the agitator 3 and not higher than the top of the cylinder. After the calcium liquid and the alkali slag are mixed and stirred evenly, the second valve 14 at the wellhead of the slag injection well 11 (C1) is opened, and the third valve 13 at the wellhead of the brine discharge well 10 (C2) is opened. The slurry passes through the screen into the slurry filling pipeline 6, enters the slag injection well 11 (C1), and finally enters the salt cavern 9 of the slag injection well. The slurry accumulates on the insoluble sediment 12 in the cavity. The slurry slowly flocculates and forms in the salt cavern 9 of the slag injection well and the salt cavern 8 of the brine discharge well to form a filling body with a certain strength. The excess water and brine in the salt cavern are discharged to the ground through the brine discharge well 10 (C2) and enter the brine storage tank 16. When the amount of alkali slag injected into the C1 well reaches 201,000 cubic meters, the C1 and C2 wells alternately inject alkali slag to complete the filling of the C1-C2 well group. At present, the well group is still in the filling operation.

[0070] According to the data collected during production, a total of 210,000 cubic meters of alkaline slag was injected into the C1 well over the past five years, with an average annual injection of 42,000 cubic meters. A total of 417,000 cubic meters of slag was injected into the C2 well over the past six years, with an average annual injection of 69,500 cubic meters. The slag filling operation is still in progress and the well has not been sealed yet.

[0071] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A pre-buried basement type alkali slag injection well filling salt cave slurry mixing device, characterized in that: It comprises a slurry mixing tank (1), a calcium liquid storage tank (17), a brine storage tank (16), a slag injection well (11), a brine drainage well (10) and a salt cave; The slurry mixing tank (1) is vertical, the upper cylinder is cylindrical, the bottom head is ellipsoidal, the slurry mixing tank (1) is pre-buried underground, the upper opening of the cylinder is half closed and half open, and an agitator (3) is installed in the slurry mixing tank (1); The calcium liquid storage tank (17) is connected to a calcium liquid pipeline (20), one end of the calcium liquid pipeline (20) extends above the open portion of the upper opening of the cylinder, and the calcium liquid pipeline (20) is connected to a first valve (19); The salt cavern is an underground space formed by mining rock salt resources using a connected well water solution method. The two salt caverns are connected underground, and the slag injection well (11) and the brine drainage well (10) are respectively opened above the two salt caverns; The slurry mixing pool (1) is connected to the slag injection well (11) via a slurry filling pipeline (6), the slurry filling pipeline (6) is connected to a second valve (14), the brine discharge well (10) is connected to a brine storage tank (16) via a brine discharge pipeline (15), the brine discharge pipeline (15) is connected to a third valve (13); The slurry mixing tank (1) has a circular hole a at the center of the bottom end cap, a suction pipe (7) is connected to the circular hole a, a fourth valve (18) is connected to the suction pipe (7), one end of the suction pipe (7) extends to the upper part of the open part of the upper opening of the cylinder, a filter screen a is provided at the upper outlet of the suction pipe (7), and the filter screen a is detachable; The upper cylinder of the slurry mixing tank (1) is 30 to 50 mm above the ground, the inner diameter of the cylinder of the slurry mixing tank (1) is D=3 to 5 m, the upper cylinder height is H=6 to 8 m, the bottom head ellipsoid bottom height is h=1.1 to 1.8 m, and the wall thickness of the slurry mixing tank (1) is 6 to 12 mm; two spliced ​​steel guide plates open to the feed inlet are welded at the junction of the closed part and the open part of the slurry mixing tank (1), and the two guide plates are both rectangular. The lower guide plate is inclined at an angle of 40 to 60 degrees, and the upper guide plate is vertical. Vertical baffles (2) are evenly arranged around the cylinder of the slurry mixing tank (1). The width of the baffles (2) is 0.1 to 0.5 times the inner diameter of the cylinder of the slurry mixing tank (1). The upper part of the baffles (2) is 0.1 to 0.6 m away from the mouth of the slurry mixing tank (1), and the lower part is 1.2 to 2.0 m away from the bottom end of the bottom head. The number of baffles (2) is 4 to 6. The diameter of the circular hole a is 40 to 60 mm, the inner diameter of the suction pipe (7) is 60 to 80 mm, the suction pipe (7) directly reaches the vertical material guide plate above the top closed part of the slurry mixing tank (1), and the suction pump is arranged above the top closed part of the slurry mixing tank (1); the outlet of the suction pipe (7) is connected to a rubber hose, the hose is suspended on the vertical material guide plate, a fourth valve (18) is arranged at the pipe mouth of the suction pipe (7), the fourth valve (18) is located between the filter screen a and the rubber hose, the fourth valve (18) is opened, the suction pump is turned on, the filter residue and the slurry enter the suction pipe (7), the slurry re-enters the slurry mixing tank (1) through the rubber hose, and the filter residue remains at the filter screen a at the pipe mouth, the pore size of the filter screen a is 1.25 to 2.5 mm.

2. A pre-buried underground alkali slag injection well filling salt cave slurry mixing device as claimed in claim 1, characterized in that: The agitator (3) is a double-layer six-blade oblique-paddle agitator (3), comprising an agitator shaft, an impeller and a transmission device, wherein the agitator shaft is fixedly mounted at the top center of the slurry mixing tank (1), the impeller is double-layered, each layer has 6 blades (5), and the angle between the blades and the moving direction is -30 to 60 degrees; the diameter of the blades (5) is 1.5 to 2.5 meters, the distance between the double-layer impellers is 2 to 3 meters, and the ratio of the pitch to the blade diameter is 0.7 to 0.9; the transmission device comprises a motor, a reducer, a coupling, a frame and a base mounted and fixed above the top closed part of the slurry mixing tank (1).

3. A pre-buried basement type alkali slag injection well filling salt cave slurry mixing device as claimed in claim 2, characterized in that: A circular hole b is provided on the side wall of the slurry mixing tank (1) between the double-layer blades (5) of the agitator (3), the circular hole b is located between the slurry mixing tank (1) and the baffle (2), and the aperture of the circular hole b is 150 to 250 mm; a filter screen b is provided at the mouth of the circular hole b, and the aperture of the filter screen b is 0.5 to 1.25 mm; the circular hole b is connected to a slurry filling pipeline (6), the diameter of the slurry filling pipeline (6) is 170 to 220 mm, a second valve (14) is installed on the slurry filling pipeline (6), and the slurry is pumped to the underground target salt cavern through the slurry filling pipeline (6); the barrel, the head, the agitator (3), the guide plate and the baffle (2) of the slurry mixing tank (1) are all made of stainless steel, and the filter screen a and the filter screen b are made of carbon steel.

4. A pre-buried underground alkali slag injection well filling salt cave slurry mixing device as claimed in claim 1, characterized in that: The technical casing diameters of the slag injection well (11) and the brine drainage well (10) are 139.7 mm, 177.8 mm or 244.5 mm, and the diameters of the slurry filling pipeline, calcium liquid pipeline and brine drainage pipeline on the ground are 150-250 mm; flow meters and pressure gauges are installed at the wellheads of the slag injection well (11) and the brine drainage well (10) to record the injection and drainage flow rates and the wellhead pressure.

5. A method for filling salt caverns with alkali slag by injecting alkali slag into wells, using the pre-buried underground alkali slag injection and salt cavern filling slurry mixing device as claimed in claim 2, characterized in that The steps include: S1, opening the first valve (19) on the calcium liquid pipeline (20), transferring the calcium liquid in the calcium liquid storage tank (17) to the slurry mixing tank (1), injecting the calcium liquid until the liquid level in the slurry mixing tank (1) reaches 1 / 2 of the double-layer impeller, closing the first valve (19), and turning on the agitator (3); S2, the slag truck dumps the pre-treated alkali slag into the slurry mixing tank (1), and continues to inject calcium solution according to the proportion. The liquid level in the slurry mixing tank (1) is preferably higher than the blades (5) of the agitator (3) and not higher than the top of the cylinder; S3, after the slurry is fully stirred, the second valve (14) on the slurry filling pipeline is opened to transport the prepared slurry to the target salt cavern; S4, the slurry injected into the underground salt cavern flocculates and settles in the salt cavity to form a filling body, and at the same time, the brine in the salt cavern is driven out through the brine discharge pipeline (15) into the brine storage tank (16) on the ground for processing and production; S5. Repeat the above steps until the target salt cavern is completely filled and seal the salt cavern.

6. A method for filling salt caverns with alkali slag by injection into wells as claimed in claim 5, characterized in that: In S2, the pretreatment refers to the alkali slag including sand removal, clarification and filter pressing processes. The concentration of the alkali slag after the pretreatment is above 40%, and is mainly powder particles.

7. A method for filling salt caverns with alkali slag as claimed in claim 6, characterized in that: In the S3, alkali slag and calcium liquid are prepared into slurry according to a certain ratio, and the slurry concentration is 15% to 40%; the grouting flow rate of the slag injection well (11) is 100 to 250 cubic meters per hour, and the excess slurry in the slurry adjustment pool (1) can be transported to the mining area through the slurry filling pipeline (6).

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