Hydraulic spiral slag returning device and method for returning cut slag in in-situ leaching uranium mining well

Abstract

The invention belongs to the technical field of uranium mining and smelting, and particularly relates to a hydraulic spiral slag returning device and method for returning cut slag in an in-situ leaching uranium mining well. According to the device, continuous, active and efficient conveying and discharging of cutting slag in the cutting cavity are achieved through the synergistic effect of the rotating spiral pipe and the drill bit in combination with hydraulic pushing. Compared with the traditional methods such as pure hydraulic flushing and stirring or drill lifting slag salvaging, the device shortens the single slag return operation time to be less than 1 hour, and improves the cut slag return rate to be more than 90%, so that the construction efficiency is greatly improved, and the quality of subsequent well completion operation is ensured.

Description

Technical Field

[0001] This invention belongs to the field of uranium mining and metallurgy technology, specifically relating to a hydraulic spiral slag return device and method for slag removal in uranium wells during in-situ leaching. Background Technology

[0002] In the current domestic field of in-situ leaching uranium mining, the "cut-and-open-window type in-situ leaching uranium drilling" is widely used in in-situ leaching uranium mines. The specific structure and construction process of this type of uranium well are as follows: First, a drilling rig is used to drill vertically downwards from the ground to the underground ore body, forming an open hole; then, a PVC casing is installed in the open hole, and cement slurry is injected into the annulus area between the PVC casing and the open hole for cementing operations. After the cement slurry solidifies, a cement sheath is formed; next, a cutting tool is lowered into the PVC casing to remove the PVC casing, cement sheath, and mud skin of the open hole at the ore layer section; finally, an internal filter is installed at the removed area, and filter gravel is filled into the cutting cavity outside the filter, thus completing the construction of the cut-and-open-window type in-situ leaching uranium well.

[0003] However, several problems urgently need to be addressed during well completion operations using cutting tools. Firstly, because the diameter of the cutting cavity is significantly larger than that of the upper wellbore, the flow velocity of the completion fluid decreases as it flows back within the cutting cavity, drastically reducing its ability to carry cutting debris, making it difficult for a large amount of debris to be smoothly expelled from the cutting cavity. Secondly, the transition between the upper interface of the cutting cavity and the upper wellbore exhibits a stepped structure with a larger diameter at the bottom and a smaller diameter at the top. Simultaneously, the presence of drill pipe inside the wellbore during cutting operations creates an annular gap at the upper opening of the cutting cavity. This unique structure causes the completion fluid, when flowing back to the upper stepped section of the cutting cavity, to be reflected, forming a vortex. Furthermore, the relatively narrow annular gap further contributes to the accumulation of large cutting debris (such as large plastic pieces or cement blocks) at the diameter-changing section and the annular gap opening, making it difficult to remove.

[0004] For cut-and-open-window leaching wells, the cutting residue return rate within the cutting chamber is crucial, directly impacting well completion quality. According to relevant construction regulations, the cutting residue return rate for cut-and-open-window leaching wells should reach 80% or higher. However, in actual cutting operations, over 50% of cut-and-open-window leaching wells have a cutting residue return rate below 80%. This means that after cutting, specialized cutting residue return tools need to be lowered into the well for a secondary cutting residue return operation.

[0005] Currently, the conventional method used in domestic in-situ leaching mines to address the problem of secondary slag return is to use core tubes to be lowered into the well one by one for slag removal. However, this method has significant drawbacks, and the slag removal effect is unsatisfactory. Specifically, it can only retrieve small cement blocks, rock fragments, and small pieces of PVC casing. Larger and longer pieces of PVC casing exceeding 5 cm in length are almost impossible to retrieve (in fact, these larger and longer PVC pieces are precisely the ones that remain most in the cutting cavity). In addition, this method has low slag removal efficiency; for wells at a depth of approximately 700 m, one slag removal operation (one tube) takes 4 hours, severely impacting the construction progress and efficiency. Summary of the Invention

[0006] To overcome the problems existing in related technologies, a hydraulic spiral slag return device and method for slag removal in uranium leaching wells are provided.

[0007] According to one aspect of the present disclosure, a hydraulic spiral slag return device is provided for returning slag from a window-type uranium leaching well. The device includes: a hydraulic screw motor, an outer cylinder, and a drill bit connected sequentially from top to bottom; a slag discharge window is provided at the upper end of the outer cylinder; and the lower end of the housing of the hydraulic screw motor is fixedly connected to the upper end of the outer cylinder.

[0008] The device also includes a spiral tube disposed inside the outer cylinder, the upper end of which is fixedly connected to the rotor output end of the hydraulic screw motor, and the lower end of which is fixedly connected to the drill bit; an annular gap is formed between the spiral tube and the inner wall of the outer cylinder; the length of the outer cylinder is greater than the sum of the lengths of the spiral tube and the drill bit.

[0009] In one possible implementation, the outer cylinder is threaded to the lower end of the housing of the hydraulic screw motor; the spiral tube is threaded to the rotor output end of the hydraulic screw motor; and the drill bit is threaded to the lower end of the spiral tube.

[0010] In one possible implementation, the spiral tube is a hollow tube with continuous spiral blades welded to its surface.

[0011] In one possible implementation, the drill bit is a two- or three-winged inverted conical scraper drill bit.

[0012] In one possible implementation, an annular seal is fitted on the outer side of the upper end of the outer cylinder to seal the annular space between the outer cylinder and the wellbore.

[0013] According to another aspect of the present disclosure, a method for returning cuttings from a window-type in-situ leaching uranium well is provided, the method being applied to the aforementioned apparatus, the method comprising the following steps:

[0014] Step 1: Connect the slag return device to the lower end of the drill pipe and lower it into the well to above the cutting chamber;

[0015] Step 2: High-pressure water pumped from the ground enters the hydraulic screw motor through the drill rod, driving its rotor to rotate, which in turn drives the auger and drill bit to rotate.

[0016] Step 3: Lower the drill rod and the slag return device to allow the drill bit to enter the cutting chamber and lift up the slag inside;

[0017] Step 4: Under the combined action of the water flow from the drill bit and upward along the annular gap, and the upward squeezing force of the spiral surface of the rotating spiral tube, the cuttings move upward in the outer cylinder and are discharged from the cuttings window into the annulus between the wellbore and the drill pipe.

[0018] Step 5: The cutting debris discharged into the annulus is carried by the continuously upward-flowing water to the wellhead for discharge. At the same time, the cutting debris in the cutting chamber is continuously pumped into the outer cylinder and discharged.

[0019] The beneficial effects of this disclosure are as follows: The device of this disclosure is connected to the lower end of the drill pipe and lowered into the well, continuously, efficiently and effectively returning all sizes of cuttings (especially PVC casing slices with a length > 5cm) from the cutting chamber, and discharging them upwards to the wellhead through the wellbore (casing). Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a hydraulic spiral slag return device for returning slag from a uranium leaching well, according to an exemplary embodiment.

[0021] Figure 2 This is a schematic diagram of the appearance of a hydraulic spiral slag return device for returning slag from a uranium leaching well, according to an exemplary embodiment.

[0022] Figure 3 This is a schematic diagram illustrating a method for cutting slag in a uranium well for return leaching, according to an exemplary embodiment. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] See Figure 1 and Figure 2 The hydraulic spiral slag return device disclosed herein for slag removal in uranium leaching wells includes: a hydraulic screw motor 2, an outer cylinder 4, and a drill bit 6 connected sequentially from top to bottom; a slag discharge window 7 is provided at the upper end of the outer cylinder 4; the lower end of the outer casing of the hydraulic screw motor 2 is fixedly connected to the upper end of the outer cylinder 4; the screw rotor inside the hydraulic screw motor 2 can rotate and output mechanical energy under the drive of high-pressure water.

[0025] The device also includes a spiral tube 5 disposed inside the outer cylinder 4. The upper end of the spiral tube 5 is fixedly connected to the rotor output end of the hydraulic screw motor 2, and the lower end is fixedly connected to the drill bit 6. An annular gap is formed between the spiral tube 5 and the inner wall of the outer cylinder 4. The length of the outer cylinder 4 is greater than the sum of the lengths of the spiral tube 5 and the drill bit 6.

[0026] In one possible implementation, the outer cylinder 4 is threaded to the lower end of the housing of the hydraulic screw motor 2; the spiral tube 5 is threaded to the rotor output end of the hydraulic screw motor 2; and the drill bit 6 is threaded to the lower end of the spiral tube 5.

[0027] In one possible implementation, the spiral tube 5 is a hollow tube with continuous spiral blades welded to its surface.

[0028] In one possible implementation, the drill bit 6 is a two-winged or three-winged inverted conical scraper drill bit.

[0029] In one possible implementation, an annular seal 3 is fitted on the outer side of the upper end of the outer cylinder 4 to seal the annular space between the outer cylinder 4 and the wellbore. The annular seal can be, for example, a rubber sealing sleeve.

[0030] In one possible implementation, a method is provided for returning cuttings from a windowed uranium leaching well, the method being applied to the aforementioned apparatus, see [link to previous section]. Figure 3 The method includes the following steps:

[0031] Step 1: Connect the slag return device to the lower end of the drill pipe 9 and lower it into the well to above the cutting chamber 13;

[0032] Step 2: High-pressure water 8 is pumped from the ground and enters the hydraulic screw motor 2 through the drill rod 9, driving its rotor to rotate, which in turn drives the spiral tube 5 and the drill bit 6 to rotate.

[0033] Step 3: Lower the drill rod 9 and the slag return device so that the drill bit 6 enters the cutting chamber 13 and lifts up the slag 14 inside;

[0034] Step 4: Under the combined action of the water flow from the drill bit 6 and upward flow along the annular gap, and the upward squeezing force of the spiral surface of the rotating spiral tube 5, the cutting material 14 moves upward in the outer cylinder 4 and is discharged from the cutting material window 7 into the annulus between the wellbore 10 and the drill pipe 9.

[0035] Step 5: The cutting debris 14 discharged into the annulus is carried by the continuously upward-flowing water to the wellhead for discharge. At the same time, the cutting debris 14 in the cutting chamber 13 is continuously drawn into the outer cylinder 4 and discharged.

[0036] During the slag return process, the pump delivers high-pressure water 8 through the drill pipe 9 and downwards into the hydraulic screw 2, driving the rotor of the hydraulic screw 2 to rotate, which in turn drives the spiral tube 5 and the drill bit 6 to rotate. The drill bit 6 lifts up the slag 14 deposited in the cutting chamber 13. Under the action of the upward water flow along the annular gap between the outer cylinder 4 and the spiral tube 5, as well as the upward squeezing force on the spiral surface of the spiral tube, the slag 14 moves upward in the outer cylinder 4 until it is discharged from the slag outlet window 7 and enters the annulus between the wellbore 9 and the drill pipe. It is then carried by the upward-flowing high-pressure water to the wellhead for discharge.

[0037] During the slag return operation, the outer shells of the drill rod 9 and hydraulic screw 2 and the outer cylinder 4 do not rotate, but only move slowly downwards. The slag 14 in the cutting chamber 13 will be continuously drawn into the outer cylinder 4 and quickly discharged through the slag outlet window 7 at the upper end of the outer cylinder 4 by the water flow and spiral. Then it enters the annulus above the outer cylinder 4 and is discharged from the inlet. This achieves efficient slag return.

[0038] This invention utilizes a rotating auger tube and drill bit working in synergy, combined with hydraulic propulsion, to achieve continuous, active, and efficient transport and discharge of cutting debris (especially large PVC slices longer than 5 cm) within the cutting chamber. Compared to traditional methods such as simple hydraulic agitation or drill bit retrieval, this device reduces the time for a single cutting debris return operation to less than one hour and increases the cutting debris return rate to over 90%, significantly improving construction efficiency and ensuring the quality of subsequent well completion operations.

[0039] The mechanical conveying capacity of the spiral tube overcomes the bottleneck of easy settling and clogging of large-sized, irregularly shaped slag when relying solely on hydraulic transport. The upward mechanical extrusion force generated by the spiral surface can reliably push large pieces of residue, such as long strips, upward, fundamentally solving the problem of low return rate of large-sized slag in traditional methods.

[0040] The disclosed device has a compact structure and strong operational adaptability. It is driven by downhole power, requiring only high-pressure water from the surface without rotating the entire drill string. This makes the device compact and provides direct power transmission, making it particularly suitable for efficient operations in small-diameter wells such as those used in in-situ leaching uranium production.

[0041] The outer cylinder is designed with a reasonable length, providing ample space for the collection and upward conveying of slag. At the same time, the slag outlet window on it works in conjunction with the annular seal to ensure that the slag-water mixture can enter the upper annular space in an orderly manner.

[0042] During construction, the drill pipe and outer casing only need to be slowly lowered to achieve continuous and uninterrupted suction and discharge of cutting debris from the cutting chamber. This avoids the intermittent operations of frequent tripping in traditional methods, significantly reducing labor intensity and operational risks. Utilizing drilling fluid (high-pressure water) as the power source and carrying medium eliminates the need for additional complex equipment or power systems, ensuring good compatibility with existing drilling processes and making implementation simple, safe, and reliable.

[0043] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A hydraulic spiral slag return device for slag removal in uranium leaching wells, characterized in that, The device includes: a hydraulic screw motor (2), an outer cylinder (4) and a drill bit (6) connected in sequence from top to bottom; the upper end of the outer cylinder (4) is provided with a slag discharge window (7); the lower end of the outer shell of the hydraulic screw motor (2) is fixedly connected to the upper end of the outer cylinder (4); The device also includes a spiral tube (5) disposed inside the outer cylinder (4). The upper end of the spiral tube (5) is fixedly connected to the rotor output end of the hydraulic screw motor (2), and the lower end is fixedly connected to the drill bit (6). An annular gap is formed between the spiral tube (5) and the inner wall of the outer cylinder (4). The length of the outer cylinder (4) is greater than the sum of the lengths of the spiral tube (5) and the drill bit (6).

2. The apparatus according to claim 1, characterized in that, The outer cylinder (4) is threaded to the lower end of the housing of the hydraulic screw motor (2); the spiral tube (5) is threaded to the rotor output end of the hydraulic screw motor (2); and the drill bit (6) is threaded to the lower end of the spiral tube (5).

3. The apparatus according to claim 1 or 2, characterized in that, The spiral tube (5) is a hollow tube with continuous spiral blades welded to its surface.

4. The apparatus according to claim 1 or 2, characterized in that, The drill bit (6) is a two-wing or three-wing inverted conical scraper drill bit.

5. The apparatus according to claim 1 or 2, characterized in that, The outer cylinder (4) is fitted with an annular seal (3) on the outer side of its upper end to seal the annular space between the outer cylinder (4) and the well shaft.

6. A method for cutting slag inside a uranium well undergoing in-situ leaching, characterized in that, The method is applied to the apparatus according to any one of claims 1 to 5, and the method includes the following steps: Step 1: Connect the slag return device to the lower end of the drill pipe (9) and lower it into the well to above the cutting chamber (13); Step 2: High-pressure water (8) pumped from the ground enters the hydraulic screw motor (2) through the drill rod (9), driving its rotor to rotate, which in turn drives the spiral tube (5) and the drill bit (6) to rotate. Step 3: Lower the drill rod (9) and the slag return device so that the drill bit (6) enters the cutting chamber (13) and lifts up the slag (14) inside; Step 4: Under the combined action of the water flow from the drill bit (6) and upward flow along the annular gap, and the upward squeezing force of the spiral surface of the rotating spiral tube (5), the cutting material (14) moves upward in the outer cylinder (4) and is discharged from the cutting material window (7) into the annulus between the wellbore (10) and the drill pipe (9). Step 5: The cutting debris (14) discharged into the annulus is carried to the wellhead by the continuously upward flowing water and discharged. At the same time, the cutting debris (14) in the cutting chamber (13) is continuously drawn into the outer cylinder (4) and discharged.

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