Method and device for decomposing rare earth minerals by high-temperature reduction roasting

Abstract

The present application relates to the technical field of rare earth metallurgy, in particular to a method and device for high-temperature reduction roasting and decomposing rare earth minerals; CO is introduced into the kiln head of a rotary kiln, and the tail gas is treated after being once introduced from the middle part of the rotary kiln; then the filtered CO and newly supplemented CO are introduced into the side close to the kiln tail of the rotary kiln; thus the technical problem of unbalanced inhibition effect of Ce3+ being oxidized to Ce4+ is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth metallurgy, in particular to a method and device for high-temperature reduction roasting decomposition of rare earth minerals. BACKGROUND

[0002] At present, the main methods for decomposing rare earth minerals in the world include concentrated sulfuric acid decomposition method, caustic soda decomposition method, and oxidation roasting decomposition method. The oxidation roasting decomposition method utilizes the condition of high-temperature aeration to decompose the gold-enclosed sulfide minerals into porous oxides, so that the gold immersed therein is exposed; the oxidation roasting decomposition product needs to be leached with hydrochloric acid, and then needs to be converted by caustic soda before being subjected to a second leaching; the fluorine-containing minerals are generated after the chemical reaction in the rotary kiln, and the volatile gas enters the tail gas treatment system; meanwhile, in the roasting process, Ce3+ in the rare earth cerium ore is easily oxidized to Ce4+; in the subsequent application, a large amount of hydrochloric acid reducing agent is needed to reduce Ce4+ to Ce3+ or metallic cerium; at the same time, Ce4+ oxidizes the chloride ions in the hydrochloric acid to chlorine gas, which leads to chlorine gas overflow and air pollution.

[0003] For example, the smelting method of fluorocarbon cerium ore and the use of carbon powder in the application with the application number CN112074617A, carbon powder is added during the reduction roasting of rare earth minerals, and the carbon powder reacts with oxygen during the oxidation roasting process, thereby inhibiting the process of Ce3+ being oxidized to Ce4+; however, the effect of inhibiting Ce3+ from being oxidized is strong in the early stage of rotary roasting, and more and more Ce3+ is oxidized to Ce4+ as the material is consumed in the later stage of the reaction; the inhibiting effect is uneven at the kiln head and the kiln tail during roasting; based on this technical background, the present application provides a method and device for high-temperature reduction roasting decomposition of rare earth minerals. SUMMARY

[0004] The present application provides a method and device for high-temperature reduction roasting decomposition of rare earth minerals, aiming to solve the technical problem of uneven inhibiting effect of Ce3+ being oxidized to Ce4+.

[0005] The technical solution used in the present application is as follows: a method for high-temperature reduction roasting decomposition of rare earth minerals, comprising the following steps:

[0006] (1) roasting rare earth concentrate in a rotary kiln;

[0007] (2) introducing CO into the kiln head of the rotary kiln, and introducing the mixed gas of fluorine-containing roasting tail gas, CO, and CO2 from the middle part of the rotary kiln to the rotary kiln;

[0008] (3) introducing the mixed gas of fluorine-containing tail gas, CO, and CO2 from the first stage into a reaction tank containing NAOH; then introducing the filtered CO and newly supplemented CO into the side close to the kiln tail of the rotary kiln;

[0009] (4) the fluorine-containing roasting tail gas, CO and CO2 are secondarily guided out of the rotary kiln from the kiln tail of the rotary kiln, and the secondarily guided mixed gas is introduced into a condenser to complete self-condensation absorption of the fluorine-containing gas and produce hydrofluoric acid.

[0010] Further, the method comprises the following steps:

[0011] (5) the secondarily guided mixed gas after condensation treatment is introduced into a reaction tank containing NaOH, CO2 is removed, and the remaining CO is introduced into the rotary kiln near the kiln tail

[0012] The application further provides a device for high-temperature reduction roasting and decomposing rare earth minerals, comprising a first rotary kiln and a second rotary kiln, one end of the first rotary kiln is rotationally connected with a kiln head, the other side of the first rotary kiln is connected with the second rotary kiln through a transition part, the other side of the second rotary kiln is rotationally connected with a kiln tail, a power source is arranged on the lower side of the transition part and is rotationally connected with the first rotary kiln and the second rotary kiln, a first gas inlet is arranged on the kiln head and is connected with a CO gas source outside, a first gas outlet and a second gas inlet are arranged on the transition part and are connected with a tail gas primary treatment system, and a second gas outlet is arranged on the kiln tail and is connected with a tail gas secondary treatment system.

[0013] Further, a reverse T-shaped shunt plate is arranged in the transition part, and the inner cavity of the transition part is divided into three intervals.

[0014] Further, the tail gas primary treatment system comprises a first reaction tank containing NaOH, the first gas outlet is connected with the lower side of the first reaction tank through a pipeline, the upper side of the first reaction tank is connected with the second gas inlet through a pipeline, a first air guide device is arranged between the first reaction tank and the second gas inlet, and a gas supplementing pipeline connected with a CO gas source outside is further arranged on the pipeline between the first reaction tank and the second gas inlet.

[0015] Specifically, a driving switching unit is arranged on the pipeline between the first air guide device and the second gas inlet, the driving switching unit is in a box structure, a non-penetrating partition plate is arranged in the box, a conversion piece is arranged on the left side of the partition plate and is switched in position through a driving device, a chamber on the upper side of the driving switching unit is connected with one side of a driven switching unit through a pipeline, a chamber on the lower side of the driving switching unit is connected with the other side of the driven switching unit after being connected with a second reaction tank, the third side of the driven switching unit is connected with the second gas inlet, the driven switching unit comprises a three-way structure reversing shell, the second gas inlet is connected with the middle of the reversing shell, a reversing block is slidably connected in the reversing shell, hollow blocking rings are vertically arranged on the two sides of the reversing shell, and the diameter of the reversing block is smaller than the inner diameter of the reversing cylinder.

[0016] Further, the commutating block is flexible on both sides, the middle is a hard disc structure, and the end of the cavity is filled with magneto-rheological fluid; the inner ring of the blocking ring is embedded with a ring magnet.

[0017] Preferably, a CO2 sensor is arranged on the pipeline between the first reaction tank and the active switching unit, the CO2 sensor and the driving device are electrically connected with the control unit respectively, the CO2 sensor is used for detecting the CO2 concentration value in the pipeline after the first reaction tank is processed and transmitting the value to the control unit, and the control unit is used for calculating the average concentration value of CO2 in a period of time and controlling the driving device to switch.

[0018] Specifically, the tail gas secondary treatment system comprises a condenser, one side of the condenser is connected with the second exhaust port through a pipeline, the other side of the condenser is connected with the lower side of the third reaction tank containing NAOH through a pipeline, the upper side of the third reaction tank is connected with the second air inlet through a pipeline, and the third reaction tank is provided with the second air guiding device between the third reaction tank and the second air inlet.

[0019] The application has the following characteristics: CO is introduced into the first rotary kiln to react with oxygen therein; thus, the process of Ce3+ being oxidized to Ce4+ is inhibited; and after the first rotary kiln is treated and supplemented with CO, the first rotary kiln is introduced into the second rotary kiln, thereby solving the problem of uneven effects at the kiln head and the kiln tail.

[0020] The application has the following characteristics: CO is introduced into the first rotary kiln to react with oxygen therein; thus, the process of Ce3+ being oxidized to Ce4+ is inhibited; and after the first rotary kiln is treated and supplemented with CO, the first rotary kiln is introduced into the second rotary kiln, thereby solving the problem of uneven effects at the kiln head and the kiln tail. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the application.

[0022] Figure 2 It is a schematic diagram of the overall structure of the application.

[0023] Figure 3 It is a schematic diagram of the transition part cross-sectional structure of the application.

[0024] Figure 4 It is a schematic diagram of the first embodiment of the tail gas primary treatment system of the application.

[0025] Figure 5 is the second embodiment of the tail gas primary treatment system of the present application.

[0026] Figure 6 is the schematic diagram of the active switching unit structure of the present application.

[0027] Figure 7 is the schematic diagram of the driven switching unit structure of the present application.

[0028] Figure 8 is the schematic diagram of the tail gas secondary treatment system of the present application.

[0029] In the figure, 1 is a first rotary kiln, 2 is a second rotary kiln, 3 is a kiln head, 4 is a transition part, 5 is a kiln tail, 6 is a gear ring, 7 is a first air inlet, 8 is a first air outlet, 9 is a second air inlet, 10 is a second air outlet, 11 is a flow dividing plate, 12 is a first reaction pool, 13 is a first air induction device, 14 is an active switching unit, 15 is a driving device, 16 is a conversion piece, 17 is a second reaction pool, 18 is a driven switching unit, 19 is a CO2 sensor, 20 is a blocking ring, 21 is a reversing block, 22 is a magneto-rheological fluid, 23 is a magnet, 24 is a condenser, 25 is a third reaction pool, and 26 is a second air induction device. DETAILED DESCRIPTION

[0030] In order to make the skilled in the art understand the present application, the specific embodiments of the present application are described below in conjunction with the drawings.

[0031] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “linking” should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements; for those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] Example 1

[0033] The effect of inhibiting Ce3+ oxidation is stronger in the early stage of rotary roasting, and more and more Ce3+ is oxidized to Ce4+ as the material is consumed in the later stage of reaction; the inhibiting effect is uneven at the kiln head 3 and the kiln tail 5; the present application provides a gas treatment method for high-temperature reduction roasting and decomposition of rare earth minerals, comprising the following steps:

[0034] (1) roasting the rare earth concentrate in a rotary kiln, the roasting temperature is 900-1500℃;

[0035] (2) CO is introduced into the kiln head 3 of the rotary kiln, and fluorine-containing roasting tail gas, CO and CO2 are once guided out of the rotary kiln from the middle part of the rotary kiln;

[0036] (3) The mixed gas of the fluorine-containing tail gas, CO and CO2 once guided out is introduced into a reaction tank containing NaOH; after removing the fluorine-containing tail gas and CO2 in the mixed gas, the filtered CO is introduced into the rotary kiln near the kiln tail 5 side together with newly supplemented CO;

[0037] (4) The fluorine-containing roasting tail gas, CO and CO2 are twice guided out of the rotary kiln from the kiln tail 5 of the rotary kiln; and the twice-guided-out mixed gas is introduced into a condenser 24 to complete self-condensation absorption of the fluorine-containing gas and produce hydrofluoric acid.

[0038] The twice-guided-out mixed gas is cooled and cooled by heat exchange with cooling water, and the cooling liquid generated by cooling and cooling, i.e. nascent hydrofluoric acid, can be recovered from the circulating waste acid tank by automatic overflow or regular discharge.

[0039] (5) The twice-guided-out mixed gas treated by condensation is introduced into a reaction tank containing NaOH; after removing CO2 therein, the remaining CO is introduced into the rotary kiln near the kiln tail 5 side.

[0040] Example Two

[0041] The application provides a device for decomposing rare earth minerals through high-temperature reduction roasting, which comprises a first rotary kiln 1 and a second rotary kiln 2, one end of the first rotary kiln 1 is rotationally matched with a kiln head 3, the other side of the first rotary kiln 1 is communicated with the second rotary kiln 2 through a transition part 4, and the other side of the second rotary kiln 2 is rotationally matched with a kiln tail 5; supporting roller groups are arranged at the lower sides of the first rotary kiln 1 and the second rotary kiln 2 respectively to provide support for the first rotary kiln 1 and the second rotary kiln 2 during rotation, a double-head motor is arranged at the lower side of the transition part 4, gears are connected to the two sides of the double-head motor through keys, tooth rings 6 corresponding to the gears are arranged on the first rotary kiln 1 and the second rotary kiln 2, and the gears are in transmission cooperation with the tooth rings 6, so that the first rotary kiln 1 and the second rotary kiln 2 are driven to rotate by the double-head motor, of course, two motors can also be arranged and in transmission with the tooth rings 6 respectively, and the two motors can be kept in synchronous rotation; the kiln head 3 is provided with a first air inlet 7 communicated with the inside, the first air inlet 7 is used for being connected with a CO gas source outside; CO introduced into the first rotary kiln 1 through the first air inlet 7 reacts with oxygen therein; so as to inhibit the process that Ce3+ is oxidized into Ce4+; the transition part 4 has a cylindrical cavity structure, the two sides of the transition part 4 are rotationally matched with the first rotary kiln 1 and the second rotary kiln 2 through rotary pipe joints, of course, the two sides of the transition part 4 can be provided with necked groove structures, and the transition part 4 is matched with the first rotary kiln 1 and the second rotary kiln 2 at protruding parts corresponding to the necked groove structures; the transition part 4 is provided with a first air outlet 8 and a second air inlet 9; the first air outlet 8 and the second air inlet 9 are connected with a tail gas primary treatment system; in the first rotary kiln 1, CO reacts with oxygen therein due to sufficient CO content; tail gas in the first rotary kiln 1 is led out through the first air outlet 8, the once-led-out tail gas has small CO content and large CO2 content; the once-led-out tail gas is led out of the rotary kiln from the first air outlet 8 in the middle of the rotary kiln, introduced into a tail gas primary treatment system, and removed of fluorine-containing tail gas and CO2, and the treated CO is introduced into the transition part 4 through the second air inlet 9, so as to further supplement the CO content in the second rotary kiln 2 and increase the inhibition effect; the kiln tail 5 is provided with a second air outlet 10 communicated with the inside, the second air outlet 10 is used for being connected with a tail gas secondary treatment system; the twice-led-out tail gas has large CO2 content and small CO content.

[0042] As shown in Figure 2 The transition part 4 is provided with a reverse T-shaped flow divider 11, the inner cavity of the transition part 4 is divided into three intervals, the roasted materials pass through the lower side, the once-led-out tail gas is discharged from the right upper side, the CO treated by the tail gas primary treatment system is introduced from the left upper side, and the medium is separated by the flow divider 11.

[0043] As shown in Figure 4As shown, the tail gas primary treatment system is used to remove a small amount of fluorine-containing tail gas and a large amount of CO2, and the remaining CO is introduced into the second rotary kiln 2 to further supplement the content of CO in the second rotary kiln 2; the tail gas primary treatment system comprises a first reaction tank 12 containing NAOH, the first exhaust port 8 is connected to the lower side of the first reaction tank 12 through a pipeline, the upper side of the first reaction tank 12 is connected to the second gas inlet 9 through a pipeline, and the first reaction tank 12 and the second gas inlet 9 have a first air guide device 13; at the same time, a gas supplementing pipe is arranged on the pipeline between the first reaction tank 12 and the second gas inlet 9, the gas supplementing pipe is used to be connected with an external CO gas source to supplement CO into the system; the mixed gas is introduced into the first reaction tank 12 containing NAOH; and the fluorine-containing tail gas and CO2 in the mixed gas are removed.

[0044] Since the content of CO and the content of CO2 in the once-derived tail gas are not a constant value, when the content of CO2 is high, the reaction cannot be complete, therefore, the pipeline between the first air guide device 13 and the second gas inlet 9 is provided with an active switching unit 14, such as Figures 5-6As shown, the active switching unit 14 is a square box structure; a left side non-through partition plate is arranged in the box; a conversion piece 16 is arranged on the left side of the partition plate; the conversion piece 16 is switched in position by a driving device 15; in one embodiment, the conversion piece 16 is an L-shaped plate structure, which is rotationally fitted on the corresponding end of the partition plate; the driving device 15 is a stepping motor, the motor shaft of which is linked with the rotation position of the conversion piece 16; the rotation of the partition plate is driven by the stepping motor, so as to switch the upper and lower chambers; in another embodiment, the conversion piece 16 is a plate structure, which is slidingly fitted on the corresponding end of the partition plate; the driving device 15 is a push rod, the push head of which is fixed with the rotation position of the conversion piece 16; the push rod is arranged outside the active switching unit 14; the position of the partition plate is changed by the sliding of the push rod, so as to switch the upper and lower chambers; the chamber on the upper side of the active switching unit 14 is connected with one side of the driven switching unit 18 through a pipeline; the chamber on the lower side of the active switching unit 14 is communicated into the lower side of the second reaction tank 17 through a pipeline; the upper side of the second reaction tank 17 is connected with the other side of the driven switching unit 18 through a pipeline; the third side of the driven switching unit 18 is connected with the second gas inlet 9; a CO2 sensor 19 is arranged on the pipeline between the first reaction tank 12 and the active switching unit 14; the CO2 sensor 19 and the driving device 15 are electrically connected with a control unit (which can be a single-chip microcomputer, a PLC, etc.) respectively; the CO2 sensor 19 is used to detect the CO2 concentration value in the pipeline after the treatment of the first reaction tank 12, and transmit the value to the control unit; the control unit is used to calculate the average concentration value of CO2 in a period of time, and control the driving device 15 to switch; when the average concentration value in a period of time is less than a preset threshold value, the driving device 15 controls the first reaction tank 12 to be communicated with the chamber on the upper side of the active switching unit 14; the exhaust gas once led out after the treatment of the first reaction tank 12 is communicated into the driven switching unit 18 from the left side of the driven switching unit 18; the reversing block 21 moves rightward, and contacts the blocking ring 20 to block the right side; when the average concentration value in a period of time is greater than the preset threshold value, the driving device 15 is switched to control the first reaction tank 12 to be communicated with the chamber on the lower side of the active switching unit 14; the exhaust gas once led out after the treatment of the first reaction tank 12 is communicated into the second reaction tank 17 for secondary treatment, and then is communicated into the driven switching unit 18 from the right side of the driven switching unit 18; the reversing block 21 moves leftward, and contacts the blocking ring 20 to block the left side; the linkage of the active switching unit 14 and the driven switching unit 18 is used to switch in the gas pipeline to prevent backflow, and maintain the large-flow gas transmission.

[0045] As Figure 7As shown, the driven switching unit 18 includes a three-way structure reversing shell, the middle of the reversing shell is connected with the second air inlet 9; the reversing shell is slidably connected with a reversing block 21; the reversing shell is vertically provided with a hollow blocking ring 20 on both sides; the diameter of the reversing block 21 is smaller than the inner diameter of the reversing cylinder; further, the two sides of the reversing block 21 are flexible cavity structures, and the middle is a hard disc-shaped structure, the cavity structure is deformed after being extruded, which is a TPU flexible material, and can adapt to the reversing block 21 and the blocking ring 20, the end cavity of the reversing block 21 is tightly attached to the blocking ring 20 after deformation; the end cavity of the reversing block 21 is filled with a magneto-rheological fluid 22; the magneto-rheological fluid 22 is a special suspension system formed by uniformly dispersing micron-sized magnetizable particles in a specific carrier mother liquor and additives; under the action of an external magnetic field, it exhibits the characteristics of a non-Newtonian fluid, and can change from a free-flowing liquid to a semi-solid or even a solid within milliseconds, showing strong controllable rheological properties; the inner ring of the blocking ring 20 is inlaid with a ring-shaped magnet 23, the end cavity of the reversing block 21 is tightly attached to the blocking ring 20 after deformation, and has a buffering function, and is solidified and sealed under the action of the magnet 23.

[0046] The main purpose of the tail gas secondary treatment system is to treat the secondary derived mixed gas containing a large amount of fluorine-containing tail gas; the tail gas secondary treatment system includes a condenser 24, one side of the condenser 24 is connected with the second air outlet 10 through a pipeline, the other side of the condenser 24 is connected with the lower side of a third reaction tank 25 containing NAOH through a pipeline, the upper side of the third reaction tank 25 is connected back to the second air inlet 9 through a pipeline, and the third reaction tank 25 and the second air inlet 9 have a second air induction device 26; the secondary derived mixed gas is cooled and cooled through heat exchange with cooling water, and the cooling liquid generated during cooling, i.e. nascent hydrofluoric acid, can be recovered from the circulating waste acid tank through automatic overflow or periodic discharge; the main purpose of the third reaction tank 25 containing NAOH is to remove CO2 in the secondary derived mixed gas to retain CO, and the CO is recycled into the second air inlet 9 for continuous utilization.

[0047] If the fixing method is not introduced separately in the above, the general technical means of the skilled in the art, welding, nesting, or threaded fixing, etc. are used.

[0048] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0049] The above-mentioned embodiments of the present application are not intended to limit the scope of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall fall within the scope of the claims of the present application.

Claims

1. An apparatus for high temperature reduction roasting decomposition of rare earth minerals, characterized in that, The application relates to a double-rotary kiln system for CO2 reduction, which comprises a first rotary kiln (1) and a second rotary kiln (2), one end of the first rotary kiln (1) is rotationally matched with a kiln head (3), the other side of the first rotary kiln (1) is communicated with the second rotary kiln (2) through a transition part (4), the other side of the second rotary kiln (2) is rotationally matched with a kiln tail (5); a power source is arranged at the lower side of the transition part (4) and is linked with the first rotary kiln (1) and the second rotary kiln (2); a first gas inlet (7) for connecting with an external CO source is arranged on the kiln head (3); a first exhaust port (8) and a second gas inlet (9) are formed on the transition part (4); the first exhaust port (8) and the second gas inlet (9) are respectively connected with the gas inlet and outlet sides of a tail gas primary treatment system; a second exhaust port (10) is arranged on the kiln tail (5) and is connected with a tail gas secondary treatment system; the tail gas primary treatment system comprises a first reaction tank (12) containing NAOH, the first exhaust port (8) is communicated into the lower side of the first reaction tank (12) through a pipeline, the upper side of the first reaction tank (12) is connected with the second gas inlet (9) through a pipeline, and a first air guide device (13) is arranged between the first reaction tank (12) and the second gas inlet (9); meanwhile, a gas supplementing pipe for connecting with the external CO source is arranged on the pipeline between the first reaction tank (12) and the second gas inlet (9); a driving switching unit (14) is arranged on the pipeline between the first air guide device (13) and the second gas inlet (9), the driving switching unit (14) is a box structure; a non-through partition plate is arranged in the box, a conversion piece (16) is arranged on the left side of the partition plate, the conversion piece (16) is switched in position through a driving device (15); a chamber located on the upper side of the driving switching unit (14) is connected with one side of a driven switching unit (18) through a pipeline, and a chamber located on the lower side of the driving switching unit (14) is connected with the other side of the driven switching unit (18) after being communicated with a second reaction tank (17); the third side of the driven switching unit (18) is connected with the second gas inlet (9); the driven switching unit (18) comprises a reversing shell with a three-way structure, the second gas inlet (9) is connected with the middle of the reversing shell; a reversing block (21) is slidably connected in the reversing shell; hollow blocking rings (20) are vertically arranged on the two sides of the reversing shell; the diameter of the reversing block (21) is smaller than the inner diameter of the reversing shell.

2. The apparatus for high temperature reduction roasting decomposition of rare earth minerals according to claim 1, characterized in that, A reverse T-shaped shunt plate (11) is arranged in the transition part (4) and divides the inner cavity of the transition part (4) into three intervals.

3. The apparatus for high temperature reduction roasting decomposition of rare earth minerals according to claim 1, characterized in that, The two sides of the reversing block (21) are flexible cavity structures, the middle part is a hard disc-shaped structure, and the end cavity of the reversing block (21) is filled with a magneto-rheological fluid (22); a ring-shaped magnet (23) is inlaid in the inner ring of the blocking ring (20).

4. The apparatus for high temperature reduction roasting decomposition of rare earth minerals according to claim 1, characterized in that, A CO2 sensor (19) is arranged on the pipeline between the first reaction tank (12) and the active switching unit (14), the CO2 sensor (19) and the driving device (15) are electrically connected with the control unit respectively, the CO2 sensor (19) is used for detecting the CO2 concentration value in the pipeline after the first reaction tank (12) is processed and transmitting the CO2 concentration value to the control unit, the control unit is used for calculating the average CO2 concentration value in a period of time and controlling the driving device (15) to switch.

5. The apparatus for high temperature reduction roasting decomposition of rare earth minerals according to claim 1, characterized in that, The tail gas secondary treatment system comprises a condenser (24), one side of the condenser (24) is connected with the second exhaust port (10) through a pipeline, the other side of the condenser (24) is connected with the lower side of a third reaction tank (25) containing NAOH through a pipeline, the upper side of the third reaction tank (25) is connected back to the second air inlet (9) through a pipeline, and the third reaction tank (25) is provided with a second air guiding device (26) between the third reaction tank (25) and the second air inlet (9).

6. A method for high-temperature reduction roasting decomposition of rare earth minerals using the high-temperature reduction roasting decomposition device for rare earth minerals according to claim 1, characterized in that: The method comprises the following steps: (1) roasting the rare earth concentrate in a rotary kiln; (2) introducing CO into the kiln head (3) of the rotary kiln, and introducing the fluorine-containing roasting tail gas, CO and CO2 from the middle part of the rotary kiln to the rotary kiln for the first time; (3) introducing the mixed gas of the fluorine-containing tail gas, CO and CO2 for the first time into a reaction tank containing NAOH, and then introducing the filtered CO and the newly supplemented CO into the side of the rotary kiln close to the kiln tail (5); (4) introducing the fluorine-containing roasting tail gas, CO and CO2 from the kiln tail (5) of the rotary kiln to the rotary kiln for the second time, and introducing the mixed gas for the second time into a condenser (24) to complete the self-condensation absorption of the fluorine-containing gas and generate hydrofluoric acid.

7. The method of claim 6, wherein the rare earth mineral is decomposed by high-temperature reduction roasting. The method comprises the following steps: (5) introducing the mixed gas for the second time treated by condensation into a reaction tank containing NAOH, removing CO2 therefrom, and then introducing the remaining CO into the side of the rotary kiln close to the kiln tail (5).

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