Radioactive contamination metal melting and extracting machine and method for manufacturing shot particles

Abstract

A radioactive contaminated metal melting and extracting machine and a method for manufacturing pelletized particles. For low radioactive contaminated metal generated by nuclear facility decommissioning, after cutting and oxidation pretreatment, the metal is smelted and decontaminated, and clean molten steel is centrifugally thrown out by the melting and extracting machine to form capsule-shaped pelletized particles. The melting and extracting machine includes a bottom moving mechanism, a screw rod lifting mechanism and an upper executing mechanism, the outer cylindrical surface of the melting and extracting head is provided with multiple sets of annularly distributed circumferential protrusions, U-shaped circumferential shaping grooves and axial partition grooves are formed between adjacent protrusions, and droplet separation and cooling shaping are controlled by a rotation speed of 800-1500 rpm. After screening and radioactive detection, the pelletized particles are used for decontamination of metal surfaces in the nuclear industry to form a "decontamination-regeneration-reuse" closed loop system. The present application solves the imbalance between supply and demand of the traditional smelting barrel process, realizes the resource utilization of radioactive waste through precise groove body design and process parameter coordination, improves the size uniformity and mechanical properties of the pelletized particles, and meets the green and low-carbon demand of nuclear facility decommissioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radioactive contaminated metal treatment, and particularly relates to a radioactive contaminated metal melting and extracting machine and a manufacturing method of shot particles. BACKGROUND

[0002] In the decommissioning process of nuclear power facilities, the disposal of low radioactive contaminated metals (such as pipes, valves, structural parts, etc.) is an important issue of radioactive waste management.

[0003] At present, the mainstream disposal method for low radioactive contaminated metals in the industry is to recycle after smelting and decontamination. The principle of smelting and decontamination is to make the radioactive nuclides attached to the surface of the metal separate from the matrix through high-temperature smelting, and float to the surface of the molten steel along with the slag formed during smelting (the prerequisite for forming slag is to add slagging materials during smelting), and realize radioactive decontamination through slag separation. The decontaminated metal is usually processed into product barrels (used for the storage of raw materials or intermediate products or products) required by uranium mining enterprises or packaging barrels (used for the solidification of high-level radioactive waste for deep burial disposal) required for the disposal of high-level radioactive waste.

[0004] Such disposal method has certain rationality in the early stage of nuclear industry development, but its limitations are increasingly prominent with the coming of the wave of global nuclear power plant and nuclear facility decommissioning. According to the statistics of the International Atomic Energy Agency (IAEA), the annual increment of low radioactive contaminated metals generated by the decommissioning of global nuclear facilities has reached hundreds of thousands of tons, and the market demand for product barrels and packaging barrels can only consume less than 40% of the volume, and the remaining low radioactive contaminated metals face the risk of long-term accumulation.

[0005] In summary, it is of great significance to develop a disposal scheme with high-efficiency decontamination and recycling value for low radioactive contaminated metals. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a radioactive contaminated metal melting and extracting machine and a manufacturing method of shot particles. It develops a disposal scheme with high-efficiency decontamination and recycling value for low radioactive contaminated metals, promotes the transformation of radioactive waste resources, and provides key technical support for the sustainable development of the industry.

[0007] The technical scheme of the present application is: a radioactive contaminated metal melting and extracting machine, comprising a bottom moving mechanism, a middle lifting mechanism and an upper executing mechanism connected in sequence from bottom to top; the upper end of the middle lifting mechanism is provided with a mounting plane; the upper executing mechanism comprises a worm gear reducer, a motor, a rotating shaft and a melting and extracting head; the worm gear reducer is fixedly installed on the mounting plane and is provided with a power input butt joint and a power output butt joint; the output shaft of the motor is connected with the power input butt joint of the worm gear reducer; the rotating shaft is horizontally rotatably installed on the mounting plane through bearings and bearing seats at both ends, and is connected with the power output butt joint of the worm gear reducer through a shaft coupling at one end and is fixedly connected with the melting and extracting head at the other end; the melting and extracting head is in a cylindrical shape with a diameter larger than that of the rotating shaft, is fixedly connected with the rotating shaft at one end and is arranged in line with the axis of the rotating shaft, and is wholly suspended outside the mounting plane; a plurality of groups of circumferential ribs extending in the axial direction are arranged on the outer circular surface of the melting and extracting head, one group of circumferential ribs occupies a rectangular area on the outer circular surface of the melting and extracting head and extends from one end to the other end in the axial direction, all groups of circumferential ribs are evenly arranged in a ring shape on the outer circular surface of the melting and extracting head, one group of circumferential ribs comprises a plurality of circumferential ribs arranged in parallel at equal intervals, and a circumferential shaped groove is formed between any two adjacent circumferential ribs in one group of circumferential ribs, and an axial partition groove is formed between any two adjacent groups of circumferential ribs, the axial partition groove is perpendicular to and communicates with all circumferential shaped grooves in the two groups of circumferential ribs on both sides.

[0008] The further technical scheme of the present application is: the width direction cross section of the circumferential shaped groove and the axial partition groove is in a U shape; accordingly, the connection between the lower end of any one circumferential rib and the outer circular surface of the melting and extracting head is circularly arc transitioned.

[0009] The further technical scheme of the present application is: the bottom moving mechanism comprises a track and an electric trolley; the track is fixedly installed on the ground; the electric trolley comprises a bearing plate and an electric roller fixedly installed at the lower end of the bearing plate, the electric trolley is rotatably installed on the track through the electric roller and reciprocally moves along the track through the power provided by the electric roller.

[0010] The further technical scheme of the present application is: the middle lifting mechanism is a screw nut lifting machine, and the upper end of the middle lifting mechanism is provided with a lifting plate, and the upper surface of the lifting plate is the mounting plane.

[0011] The further technical scheme of the present application is: the width of the upper end of the circumferential shaped groove is 0.9-1.1mm, and the length of the circumferential shaped groove is 2-4mm.

[0012] The further technical scheme of the present application is: the width of the upper end of the circumferential shaped groove is 1.0mm, and the length of the circumferential shaped groove is 3mm.

[0013] The technical scheme of the present application is: a low-radioactive contamination metal shot particle manufacturing method applied to the radioactive contamination metal melting extraction machine, and the steps are as follows:

[0014] S01, raw material pretreatment:

[0015] A, cutting treatment: cutting the low-radioactive contamination metal generated in nuclear decommissioning into small pieces of waste material meeting the feeding requirements of the smelting furnace;

[0016] B, oxidation treatment: putting the small pieces of waste material after cutting into a heat treatment furnace for oxidation treatment to remove organic matter attached to the surface of the metal and promote the generation of an oxide skin on the surface of the metal;

[0017] In this step, the low-radioactive contamination metal has a radioactivity of less than 5000 Bq / g;

[0018] S02, smelting decontamination:

[0019] A, start smelting: putting the small pieces of waste material after oxidation treatment and slag-making materials into the smelting furnace together, starting the smelting furnace, and smelting it into molten steel, during the smelting process, the radioactive nuclides on the surface of the small pieces of waste material are separated from the matrix and float on the slag;

[0020] B, slag separation: removing the radioactive slag floating on the surface of the molten steel by a slag removal device or an inert gas blowing process to obtain clean molten steel meeting the radioactivity level standard;

[0021] S03, melting extraction mechanism pelletizing:

[0022] A, equipment preparation: driving the middle lifting mechanism to move upwards, driving the upper execution mechanism to raise the height, making the melting extraction head higher than the liquid level of the molten steel in the smelting furnace; driving the electric trolley to move along the track, making the melting extraction head move to the top of the liquid level of the molten steel;

[0023] B, melting extraction operation: starting the motor, the motor drives the rotating shaft and the melting extraction head through the worm gear reducer box; driving the middle lifting mechanism to move downwards, when the rotating melting extraction head contacts the liquid level of the molten steel, the molten steel is immersed into the circumferential shaping groove on the outer circular surface of the melting extraction head and is centrifugally thrown out with the rotation of the melting extraction head;

[0024] C, particle shaping: the thrown-out metal liquid droplets are cooled and solidified into shot particles in the air and fall into the pre-placed receiving hopper on the ground; the shape and size of the shot particles are determined by the circumferential shaping groove and the axial partition groove; the shot particles are in the shape of a capsule, which is a cylindrical body with hemispherical ends;

[0025] In this step, the rotating speed of the melting extraction head is 800-1500 rpm under the premise of normal temperature.

[0026] The further technical solution of the present application is that it further comprises S04-S05 steps connected after S03 step;

[0027] S04, shot blasting sorting: using a vibrating sieve sorting device to sort the shot blasting particles according to particle size, and removing unqualified products to ensure that the size of the shot blasting particles meets the operation standard of the shot blasting equipment;

[0028] S05, shot blasting radioactive detection: detecting the radioactivity of the screened shot blasting particles to ensure that they meet the exemption limit value requirements of nuclear industry self-consumption materials.

[0029] The further technical solution of the present application is that when the rotational speed of the melt extraction head is between 800-1000 rpm, it is low speed, at this time the centrifugal force is small, the liquid column separates slowly from the tank, the initial speed of the liquid column when separating is small, the flight time is prolonged, and the liquid column naturally cools and solidifies when flying in the air; when the rotational speed of the melt extraction head is between 1200-1500 rpm, it is high speed, at this time the centrifugal force is large, the liquid column separates quickly from the tank, the initial speed of the liquid column when separating is large, and the flight time is shortened.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. By converting the contaminated metal into functional materials (shot blasting particles) for nuclear industry self-consumption, a closed-loop system of decontamination-regeneration-reuse is constructed, the resource transformation of radioactive waste is promoted, and key technical support is provided for the sustainable development of the industry.

[0032] 2. The circumferential shaping groove and the axial partition groove of the melt extraction head realize efficient forming of the capsule-shaped structure of the shot blasting particles through precise geometric design (U-shaped cross section + 3mm groove length + 1mm groove width) and the synergistic effect of the rotational speed parameters (800-1500 rpm) of the melt extraction head. The structure of the circumferential shaping groove and the axial partition groove directly controls the shape and size of the shot blasting particles, and the dynamic balance of the surface tension and cooling rate of the liquid column ensures the final stability of the shape of the shot blasting particles. The ring-shaped uniform distribution design of multiple circumferential ridges ensures the consistency of the size of the shot blasting particles, avoids the distortion of the shape of the shot blasting particles caused by uneven local molten steel flow rate, and adapts to the uniformity requirements of the shot blasting equipment for the shot blasting particles.

[0033] 3. The rotational speed setting of the melt extraction head combines the physical properties and cooling conditions of the molten steel, the forming requirements of the shot blasting particles, and the structural design of the melt extraction machine, and is set between 800-1500 rpm, which can meet the following requirements: I. balance of centrifugal force and surface tension (centrifugal force is sufficient to overcome surface tension of molten steel to realize uniform separation of molten steel liquid column); II. most of the prepared shot blasting particles adapt to the size of the circumferential shaping groove (the groove length of the circumferential shaping groove directly determines the length of part of the shot blasting particles, but high rotational speed will lead to frequent centrifugal cutting, thereby causing a large number of liquid columns to have too short length, and low rotational speed will do the opposite).

[0034] The present invention will be further described below with reference to the figures and embodiments. Attached Figure Description

[0035] Figure 1 A schematic diagram of a radioactive contaminated metal melting and extraction machine from a first perspective;

[0036] Figure 2 A schematic diagram of a radioactive contaminated metal melting and drawing machine from a second perspective;

[0037] Figure 3 This is a schematic diagram of the structure of the fusion tap from the first perspective;

[0038] Figure 4 This is a schematic diagram of the fusion tap structure from a second perspective;

[0039] Figure 5 This is a schematic diagram of the collar structure;

[0040] Figure 6 for Figure 5 AA section view;

[0041] Figure 7 This is a schematic diagram of the structure of one end of the shaft that connects to the worm gear reducer.

[0042] Legend: Electric trolley 11; Screw nut jack 12; Lifting plate 121; Worm gear reducer 31; Motor 32; Rotating shaft 33; Water inlet channel 331; Drainage channel 332; Water inlet hole B333; Water outlet hole B334; Melting tap 34; Circumferential protrusion 341; Circumferential shaping groove 342; Axial partition groove 343; Bearing seat 35; Coupling 36; Collar 371; First annular groove 3711; Second annular groove 3712; Water inlet hole A3713; Water outlet hole A3714; Water inlet pipe 372; Water outlet pipe 373. Detailed Implementation

[0043] Example 1:

[0044] like Figures 1-7 As shown, the radioactive contaminated metal melting and drawing machine includes a bottom moving mechanism, a middle lifting mechanism, and an upper execution mechanism connected in sequence from bottom to top.

[0045] The bottom moving mechanism includes a track (not shown) and an electric trolley 11. The track is fixedly installed on the ground. The electric trolley 11 includes a support plate and electric rollers fixedly installed at the lower end of the support plate. The electric trolley is rolled on the track by the electric rollers and moves back and forth along the track by the power provided by the electric rollers.

[0046] The middle lifting mechanism is a screw nut lifter 12, the upper end of which is provided with a lifting plate 121, and the upper surface of the lifting plate 121 is a mounting plane.

[0047] The upper actuating mechanism comprises a worm gear reducer 31, a motor 32, a rotating shaft 33 and a melting tap 34. The worm gear reducer 31 is fixedly installed on the mounting plane, and is provided with a power input butt joint and a power output butt joint. The output shaft of the motor 32 is connected with the power input butt joint of the worm gear reducer 31. The rotating shaft 33 is horizontally rotatably installed on the mounting plane through bearings (not shown in the figure) and a bearing seat 35 at both ends, and is connected with the power output butt joint of the worm gear reducer 31 through a shaft coupling 36 at one end, and is fixedly connected with the melting tap 34 at the other end.

[0048] The melting tap 34 is in a cylindrical shape with a diameter larger than that of the rotating shaft 33, and is fixedly connected with the rotating shaft 33 at one end and arranged in line with the axis of the rotating shaft 33, and the whole is suspended outside the mounting plane. A plurality of groups of circumferential ribs extending in the axial direction are arranged on the outer cylindrical surface of the melting tap 34, one group of circumferential ribs occupies a rectangular area on the outer cylindrical surface of the melting tap 34 and extends from one axial end of the melting tap 34 to the other axial end, all groups of circumferential ribs are arranged in a ring shape on the outer cylindrical surface of the melting tap 34, one group of circumferential ribs comprises a plurality of circumferential ribs 341 arranged in parallel at equal intervals, and a circumferential shaped groove 342 is formed between any two adjacent circumferential ribs 341 in one group of circumferential ribs, and an axial partition groove 343 is formed between any two adjacent groups of circumferential ribs, which is perpendicular to and communicates with all circumferential shaped grooves 342 in the two groups of circumferential ribs on both sides. The axial partition groove and the circumferential shaped groove are perpendicular and communicate with each other, which can divide the continuous liquid stream of molten steel into independent liquid columns, and the width of the axial partition groove cooperates with the rotating centrifugal force to uniformly cut the liquid column when it is thrown out, forming discrete molten steel segments. After the liquid column leaves the circumferential shaped groove, the surface tension drives its two ends to contract into a hemisphere with the lowest energy, while the middle section remains cylindrical due to rapid cooling, and finally forms a capsule-shaped particle (cylindrical body + hemispherical end).

[0049] Preferably, the width direction section of the circumferential shaping groove 342 and the axial partition groove 343 are both U-shaped; accordingly, the connection between the lower end of any circumferential convex strip 341 and the outer circumferential surface of the melt extraction head 34 is arc transitioned. The width of the upper end of the circumferential shaping groove 342 is 1.0 mm, and the length of the circumferential shaping groove 342 is 3 mm. The technical effects brought by these two features (shape + size) are: the U-shaped section of the circumferential shaping groove 342 is used to guide the molten steel to be evenly distributed along the groove body, the molten steel splashed out by the high-speed rotation of the melt extraction head 34 forms a nearly cylindrical liquid column due to surface tension, the arc-shaped edge inside the circumferential shaping groove 342 can reduce the flow resistance and ensure the integrity of the liquid column section, and after the liquid column solidifies, it can form the cylindrical body of the shot blasting particles. The length (3 mm) and width (1 mm) of the circumferential shaping groove 342 limit the longitudinal extension range and transverse width of the liquid column, respectively, the length and width of the corresponding cylindrical part of the shot blasting particles after cooling, and realize accurate control of the size.

[0050] Preferably, the end of the melt extraction head 34 connected with the rotating shaft 33 is defined as the rear end, and the end of the melt extraction head 34 away from the rotating shaft 33 is defined as the front end; the melt extraction head 34 is provided with a cooling water cavity, and the only opening of the cooling water cavity is arranged on the end face of the melt extraction head 34 and extends to the front end of the melt extraction head 34. The front end of the rotating shaft 33 is defined as the end of the rotating shaft 33 connected with the melt extraction head 34, and the rear end of the rotating shaft 33 is defined as the end of the rotating shaft 33 away from the melt extraction head 34; the flange plate 330 is welded on the front end face of the rotating shaft 33; the rotating shaft 33 is provided with a water inlet channel 331 and a drainage channel 332, both of which are blind holes extending in the axial direction, and both of which are arranged on the flange plate 330 at the front end of the rotating shaft 33 and extend to the rear end face of the rotating shaft 33; the rotating shaft 33 is fixedly connected to the rear end face of the melt extraction head 34 through the flange plate 330, the openings of the water inlet channel 331 and the drainage channel 332 are directly communicated with the cooling water cavity of the melt extraction head 34, and the flange plate 330 of the rotating shaft 33 and the rear end face of the melt extraction head 34 are provided with an asbestos gasket for sealing.

[0051] Preferably, the upper actuator further comprises a water cooling assembly; the water cooling assembly comprises a collar 371, a water inlet pipe 372, a water outlet pipe 373, a cold source and a circulating pump; the collar 371 is provided with an axial hole through which the rotating shaft 33 passes, and the hole wall of the axial hole is provided with a first annular groove 3711 and a second annular groove 3712 at intervals, and the outer cylindrical surface of the collar 371 is provided with a water inlet hole A 3713 communicating with the first annular groove 3711 and a water outlet hole A 3714 communicating with the second annular groove 3712; one end of the water inlet pipe 372 and the water outlet pipe 373 is connected to the water inlet hole A 3713 and the water outlet hole A 3714 of the collar 371 respectively, and the other end of the water inlet pipe 372 and the water outlet pipe 373 communicates with the cold source respectively; the circulating pump is arranged between the cold source and the end of the water inlet pipe 372 or between the cold source and the end of the water outlet pipe 373. Starting the circulating pump can drive the cooling water to circulate along the path of "cold source-water inlet pipe-collar 371 water inlet hole A 3713-collar 371 first annular groove 3711-rotating shaft 33 water inlet hole B 333-rotating shaft 33 water inlet passage 331-melted extraction head 34 cooling water cavity-rotating shaft 33 water outlet passage 332-rotating shaft 33 water outlet hole B 334-collar 371 second annular groove 3712-collar 371 water outlet hole A 3714-water outlet pipe 373-cold source", when the cooling water flows through the cooling water cavity of the melted extraction head 34, it absorbs the heat of the melted extraction head 34, and when the cooling water flows through the cold source, it releases heat (obtains cold).

[0052] Brief description of the working principle of the application:

[0053] The method for manufacturing low-radioactive contamination metal shot is applied to the radioactive contamination metal melting and extracting machine, and the steps are as follows:

[0054] S01, raw material pretreatment:

[0055] A, cutting treatment: cutting the low-radioactive contamination metal generated in nuclear decommissioning into small pieces of waste material meeting the feeding requirements of the melting furnace. The small pieces of waste material include two types of plate-shaped material and three-dimensional material, the length and width of the plate-shaped material are both not more than 260 mm, and the thickness is not more than 50 mm, and the length, width and height of the three-dimensional material are all not more than 200 mm, and the thickness is not more than 50 mm.

[0056] B, oxidation treatment: putting the small pieces of waste material after cutting into a heat treatment furnace for oxidation treatment, so as to remove the organic matter attached to the surface of the metal, and to promote the generation of an oxide skin on the surface of the metal which easily peels off (the oxide skin wraps the radioactive nuclides attached to the surface of the metal).

[0057] In this step, the low-radioactive contamination metal has a radioactivity of less than 5000 Bq / g.

[0058] S02, melting and decontamination:

[0059] A, Start smelting: Put the small pieces of waste material after oxidation treatment and slag-making materials into the smelting furnace together, start the smelting furnace, and smelt it into molten steel. During the smelting process, the radionuclides on the surface of the small pieces of waste material (most of them) are separated from the matrix and float to the surface of the slag.

[0060] B, Slag separation: Remove the radioactive slag floating on the surface of the molten steel by slag removal device or inert gas blowing process to obtain clean molten steel that meets the radioactivity level standard.

[0061] In this step, the radioactivity of the clean molten steel is less than 50 Bq / g.

[0062] S03, Mechanically formed pellets:

[0063] A, Equipment preparation: Drive the middle lifting mechanism to move upwards, drive the upper execution mechanism to raise the height, and make the whole melt extraction head higher than the liquid level of the molten steel in the smelting furnace. Drive the electric trolley to move along the track, and move the melt extraction head to the top of the liquid level of the molten steel.

[0064] B, Melting extraction operation: Start the motor, and the motor drives the rotating shaft and the melt extraction head through the worm gear reducer box. Drive the middle lifting mechanism to move downwards, when the melt extraction head in rotation contacts the liquid level of the molten steel, the molten steel is immersed in the circumferential shaping groove on the outer circular surface of the melt extraction head, and is centrifugally thrown out with the rotation of the melt extraction head.

[0065] C, Pellet shaping: The metal liquid droplets thrown out are cooled and solidified into shot pellets in the air, and fall into the receiving hopper placed on the ground in advance. The shape and size of the shot pellets are determined by the circumferential shaping groove and the axial partition groove. The shot pellets are in the shape of capsules, which are cylindrical bodies with hemispherical ends.

[0066] In this step, the rotational speed of the melt extraction head is 800-1500 rpm under the premise of normal temperature (20°C).

[0067] S04, Shot separation: Separate the shot pellets by particle size using a vibrating screen separation device, and remove unqualified products to ensure that the shot pellet size meets the shot equipment operation standard.

[0068] S05, Shot radioactivity detection: Detect the radioactivity of the separated shot pellets to ensure that they meet the exemption limit value requirements of nuclear industry self-consumption materials.

[0069] Preferably, when the rotational speed of the melt extraction head is between 800-1000 rpm, it is a low speed, at which the centrifugal force is smaller, the liquid column separates from the groove slowly, the initial speed of the liquid column during separation is small, the flight time is prolonged, and the liquid column cools and solidifies naturally in the air. The forming stability is high at this speed, but the risk of liquid column adhesion needs to be monitored.

[0070] Preferably, the rotation speed of the melt extraction head is between 1200-1500 rpm, which is a high rotation speed, at which the centrifugal force is large, the liquid column separates from the tank quickly, the initial speed of the liquid column during separation is large, and the flight time is shortened. The separation efficiency is high at this rotation speed, but rapid cooling (for example, air cooling) is required to solidify the liquid column before it falls to the ground.

Claims

1. A radioactive contaminated metal melting and drawing machine, characterized by: The device comprises, from bottom to top, a bottom moving mechanism, a middle lifting mechanism, and an upper actuator; the middle lifting mechanism has an upper mounting surface; the upper actuator includes a worm gear reducer, a motor, a rotating shaft, and a welding tap; the worm gear reducer is fixedly mounted on the mounting surface, and has a power input connector and a power output connector on it; the motor's output shaft is connected to the worm gear reducer's power input connector; the rotating shaft is horizontally mounted on the mounting surface at both ends via bearings and bearing seats, with one end connected to the worm gear reducer's power output connector via a coupling, and the other end fixedly connected to the welding tap; the welding tap is cylindrical with a diameter larger than the rotating shaft's diameter, and one end is connected to... The rotating shaft is fixedly connected and arranged to coincide with the axis of the rotating shaft, and its entire body is suspended outside the mounting plane; the outer circular surface of the melting tap is provided with multiple sets of circumferential protrusions extending in the axial direction. Each set of circumferential protrusions occupies a rectangular area on the outer circular surface of the melting tap and extends from one axial end of the melting tap to the other axial end. All sets of circumferential protrusions are evenly distributed in a ring on the outer circular surface of the melting tap. Each set of circumferential protrusions contains multiple circumferential protrusions arranged in parallel at equal intervals. A circumferential shaping groove is formed between any two adjacent circumferential protrusions in a set of circumferential protrusions. An axial partition groove is formed between any two adjacent sets of circumferential protrusions. The axial partition groove is perpendicular to and connected to all the circumferential shaping grooves in the two sets of circumferential protrusions on its two sides.

2. The radioactive contaminated metal melting and extraction machine as described in claim 1, characterized in that: Both the circumferential shaping groove and the axial partition groove have U-shaped cross sections in the width direction; correspondingly, the connection between the lower four edges of any circumferential protrusion and the outer circular surface of the melting tap head is a rounded transition.

3. The radioactive contaminated metal melting and extraction machine as described in claim 2, characterized in that: The bottom moving mechanism includes a track and an electric trolley; the track is fixedly installed on the ground; the electric trolley includes a support plate and electric rollers fixedly installed at the lower end of the support plate. The electric trolley is rolled on the track by the electric rollers and moves back and forth along the track by the power provided by the electric rollers.

4. The radioactive contaminated metal melting and extraction machine as described in claim 3, characterized in that: The middle lifting mechanism is a screw nut jack, which has a lifting plate at its upper end. The upper surface of the lifting plate is the mounting plane.

5. The radioactive contaminated metal melting and extraction machine as described in claim 4, characterized in that: The width of the upper edge of the circumferential shaping groove is 0.9-1.1mm, and the length of the circumferential shaping groove is 2-4mm.

6. The radioactive contaminated metal melting and extraction machine as described in claim 5, characterized in that: The width at the upper edge of the circumferential shaping groove is 1.0 mm, and the length of the circumferential shaping groove is 3 mm.

7. A method for manufacturing shot blasting particles based on low-radioactive contaminated metal, applied to the radioactive contaminated metal melting and drawing machine according to any one of claims 1-6, characterized in that the steps are as follows: as follows: S01, Raw material pretreatment: A. Cutting process: Cutting the low-radioactive contaminated metals generated from nuclear decommissioning into small scrap pieces that meet the requirements for feeding into the smelting furnace; B. Oxidation treatment: The cut small scrap pieces are put into a heat treatment furnace for oxidation treatment to remove organic matter attached to the metal surface and promote the formation of an oxide scale on the metal surface. In this step, low-level radioactive contamination metals are those with a radioactivity level below 5000 Bq / g. S02, smelting and decontamination: A. Start the smelting process: Put the small pieces of scrap after oxidation treatment and the slag-forming material into the smelting furnace, start the smelting furnace, and melt them into molten steel. During the smelting process, the radioactive nuclides on the surface of the small pieces of scrap detach from the matrix and float to the surface with the slag. B. Slag separation: Radioactive slag floating on the surface of molten steel is removed by slag removal device or inert gas purging process to obtain clean molten steel with a radioactivity level that meets the standard. S03, melt-drawn pellets: A. Equipment preparation: Drive the middle lifting mechanism to move upward, thereby raising the upper actuator to a height so that the melting tap is higher than the molten steel surface in the melting furnace; drive the electric trolley to move along the track so that the melting tap is directly above the molten steel surface. B. Melting and drawing operation: Start the motor, and the motor drives the rotating shaft and melting and drawing head to rotate through the worm gear reducer; drive the middle lifting mechanism to move downward. When the rotating melting and drawing head contacts the surface of the molten steel, the molten steel is immersed in the circumferential shaping groove on the outer circle of the melting and drawing head, and is centrifugally thrown out as the melting and drawing head rotates. C. Particle shaping: The ejected molten metal droplets cool and solidify in the air into shot blasting particles, which fall into a receiving hopper placed on the ground beforehand; the shape and size of the shot blasting particles are determined by the circumferential shaping groove and the axial partition groove; the shot blasting particles are capsule-shaped, and the capsule shape is a cylinder with hemispherical ends; In this step, assuming the ambient temperature is normal, the rotation speed of the melting tap is 800-1500 rpm.

8. The method for manufacturing shot blasting particles based on low-radioactive contamination metals as described in claim 7, characterized in that: It also includes steps S04 to S05, which follow step S03. S04, Shot blasting sorting: Vibrating screen equipment is used to sort shot blasting particles according to particle size, remove unqualified products, and ensure that the size of shot blasting particles meets the operating standards of shot blasting equipment; S05, Shot blasting radioactivity testing: The radioactivity of the sieved shot particles is tested to ensure that they meet the exemption limits for self-consumable materials in the nuclear industry.

9. The method for manufacturing shot blasting particles based on low-radioactive contamination metals as described in claim 8, characterized in that: When the rotation speed of the melting tap is between 800-1000 rpm, it is considered a low speed. At this speed, the centrifugal force is small, the liquid column separates slowly from the tank, the initial velocity of the liquid column during separation is small, the flight time is prolonged, and the liquid column naturally cools and solidifies while flying in the air. When the rotation speed of the melting tap is between 1200-1500 rpm, it is considered a high speed. At this speed, the centrifugal force is large, the liquid column separates quickly from the tank, the initial velocity of the liquid column during separation is large, and the flight time is shortened.

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