Apparatus and method for the atmospheric decomposition of scheelite in an alkaline system

Abstract

The application relates to the technical field of scheelite extraction, and particularly discloses a device and a method for decomposing scheelite in an alkaline system under normal pressure. The device comprises a crushing unit, a grinding unit and a conveying unit, the grinding unit comprises a grinding shell and a power device, grinding blocks are fixed on the inner wall of the grinding shell, a conical cavity is arranged on the grinding blocks along a central axis, a grinding layer is arranged on the wall surface of the conical cavity, a circular table-shaped rotor is arranged in the conical cavity, a hollow rotating shaft is connected to the upper surface of the circular table-shaped rotor, a plurality of receiving grooves are arranged on the circumferential side of the circular table-shaped rotor, an expansion and contraction block is arranged in each receiving groove, and a grinding roller is rotatably connected to the outer end of the expansion and contraction block which extends out of the receiving groove. The device realizes the dual functions of grinding treatment and centrifugal screening, can make the scheelite material be ground and processed for multiple times, can make the scheelite powder be processed to be finer, and can realize multi-stage grinding processing under the action of only one set of grinding mechanism, and the use effect is excellent.

Description

TECHNICAL FIELD

[0001] The application relates to a scheelite extraction technology field, and particularly discloses a device and method for decomposing scheelite in an alkaline system under normal pressure. BACKGROUND

[0002] There are many scheelite extraction and treatment processes, and a sodium alkali decomposition method is the most important method for decomposing scheelite at present. The method can effectively decompose scheelite, but the common problem is that the alkali consumption is large, and high temperature and high pressure means need to be used to promote the decomposition of scheelite. Due to high energy consumption and large reagent consumption, the production cost is high, and a large amount of inorganic salt emission causes adverse effects on the ecology, and the low-energy industrial production of tungsten in scheelite cannot be realized.

[0003] An application No. 2016108538914 discloses a method for decomposing scheelite in an alkaline system under normal pressure. The method needs to first grind the scheelite, then add it to the alkaline system containing phytic acid radicals to react, and then separate the solid and liquid to obtain a tungsten-containing solution and a decomposition residue. The tungsten-containing solution is used for the production of ammonium paratungstate, the decomposition residue is leached with an acid solution containing sulfuric acid and then filtered, the obtained calcium sulfate can be used for building material production, and the filtrate is returned to the leaching of scheelite after adjusting the pH to realize the regeneration of the leaching agent. The application realizes the efficient decomposition of scheelite under low-temperature and normal-pressure alkaline conditions, and realizes the regeneration of the leaching agent, and the alkali consumption is greatly reduced. However, in the process of extracting scheelite under normal pressure, the scheelite needs to be finely ground into powder to improve the reaction efficiency between the subsequent powder material and the leaching agent and ensure the decomposition rate of the scheelite. However, the existing scheelite crushing equipment is a common ore crusher, which cannot crush the scheelite into fine powder, and multiple grinding equipment needs to be matched to ensure that the final scheelite powder reaches the required particle size through multiple grinding processes. The whole pre-treatment process of scheelite is not only low in efficiency, but also needs multiple grinding equipment for continuous treatment, and the energy consumption is also high. Based on this, the application provides a device and method for decomposing scheelite in an alkaline system under normal pressure. SUMMARY

[0004] The application aims to provide a device and method for decomposing scheelite in an alkaline system under normal pressure to solve the problems of low efficiency, multiple grinding equipment for continuous treatment and high energy consumption in the pre-treatment process of scheelite.

[0005] The application is realized by the following technical scheme:

[0006] A method for decomposing scheelite in an alkaline system under normal pressure, comprising the following steps:

[0007] 1) The scheelite is added to the crushing unit for primary crushing, and after crushing, it is transported to the grinding unit for primary grinding, and after a period of primary grinding, fine grinding is carried out, and the ground scheelite powder is centrifuged and screened, and all the scheelite powder is screened and collected.

[0008] 2) The sodium phytate and sodium hydroxide are quantitatively added to the deionized water and stirred to prepare a leaching agent;

[0009] 3) The collected scheelite powder is added to the leaching agent in a set amount, and then stirred for a period of time, and then solid-liquid separation is carried out.

[0010] Preferably, the stirring temperature in step 3 is 90-100 DEG C, and the stirring time is 1-2h.

[0011] The application discloses a device for the atmospheric decomposition of scheelite in the above-mentioned alkaline system, which comprises a crushing unit, a grinding unit and a conveying unit, wherein the upper and lower ends of the conveying unit are connected with the grinding unit and the crushing unit, respectively.

[0012] The grinding unit comprises a grinding machine shell and a power device, the inner wall of the grinding machine shell is fixed with a grinding block, a tapered cavity is formed in the grinding block along the central axis, a grinding layer is arranged on the wall surface of the tapered cavity, a circular truncated cone rotor is arranged in the tapered cavity in a concentric manner, the upper surface of the circular truncated cone rotor is connected with a hollow shaft which extends out of the grinding machine shell and is connected with the power device, a plurality of receiving grooves are uniformly formed in the circumferential side surface of the circular truncated cone rotor, a swelling block is arranged in each receiving groove, a grinding roller is rotatably connected to the outer end of the swelling block which extends out of the receiving groove, the grinding roller is arranged in parallel with the grinding layer and forms a grinding gap therebetween, a blind hole is formed in the inner end wall of the receiving groove, a spring connected with the swelling block is arranged in the blind hole, an inner cavity in communication with the hollow shaft is formed in the center of the grinding block, the inner end of each swelling block is connected with an inclined surface block which extends into the inner cavity, an extrusion inclined surface block is arranged in the inner cavity, and an extrusion inclined surface which acts on each inclined surface block is arranged on the extrusion inclined surface block, an extrusion rod is rotatably connected to the upper surface of the extrusion inclined surface block, and the top end of the extrusion rod which extends out of the hollow shaft is connected with a telescopic driving piece.

[0013] The lower surface of the circular truncated cone rotor is provided with a connecting rod, the lower end of the connecting rod is connected with a centrifugal sieve plate, and a circulating material lifting device is fixed outside the grinding machine shell at the upper surface side end of the centrifugal sieve plate, and the upper end of the circulating material lifting device is in communication with the upper end of the grinding machine shell.

[0014] As a further arrangement of the above solution, the power device comprises a gear box fixed on the upper surface of the grinding machine shell, the hollow rotating shaft is provided with a first gear located in the gear box, and the upper surface of the gear box is provided with a power motor, and the motor shaft of the power motor is provided with a second gear engaged with the first gear.

[0015] As a further arrangement of the above solution, a support is fixed on the upper surface of the gear box located directly above the hollow rotating shaft, and the telescopic drive is fixed on the upper end of the support, and the telescopic end of the telescopic drive is connected with the extrusion rod.

[0016] As a further arrangement of the above solution, the circumferential surface of the grinding machine shell located below the grinding block is provided with a convex ring extending outward, and the outer circumferential surface of the centrifugal sieve plate is fitted with the inner wall of the convex ring.

[0017] As a further arrangement of the above solution, the circulating material lifting device comprises a vertically fixed feed cylinder, the lower end of the feed cylinder is provided with a feed passage, the convex ring is provided with a centrifugal falling opening communicated with the feed passage, and the centrifugal falling opening is aligned with the upper surface of the centrifugal sieve plate, the feed cylinder is provided with an auger spiral blade, the end of the auger spiral blade is connected with an auger motor, the upper end of the circulating material lifting device is provided with a discharge passage, and the discharge passage is communicated with the upper surface of the grinding machine shell.

[0018] As a further arrangement of the above solution, the upper surface side end of the grinding machine shell is provided with a receiving hopper, and the lower end is provided with a discharge pipe.

[0019] As a further arrangement of the above solution, the crushing unit comprises a crusher shell, two crushing rollers are rotatably connected in the crusher shell, and a crushing motor is connected to the end of each crushing roller and arranged on the outer surface of the crusher shell, the upper end of the crusher shell is provided with a mineral material hopper, and the lower end is provided with a discharge pipe connected with the conveying unit.

[0020] As a further arrangement of the above solution, the conveying unit comprises an inclined auger conveyor, the lower end of the auger conveyor is connected with the discharge pipe, and the upper end is provided with a feeding pipe located above the mineral material hopper.

[0021] Beneficial effects:

[0022] 1. The scheelite processing device disclosed in the application, before scheelite is decomposed under normal pressure, the ore is preliminarily crushed through a crushing unit, and after crushing, the ore is fed into a grinding unit for grinding treatment, the grinding unit in the device can preliminarily grind scheelite crushed material by using the high-speed rotation of the grinding roller when the gap between the grinding roller and the grinding layer is large in the early stage of grinding treatment of the scheelite crushed material, and after a period of preliminary grinding, the grinding gap between the grinding roller and the grinding layer can be adjusted by the telescopic driving piece to realize fine grinding after preliminary grinding, so that the particle size of the scheelite powder before final leaching treatment is ensured to be within the required range, thereby ensuring the efficiency of the scheelite powder in the stirring leaching process and improving the decomposition rate of the scheelite powder.

[0023] 2. The grinding unit in the application realizes the dual functions of grinding treatment and centrifugal screening under the action of only one power device, and can cyclically lift and convey the unscreened scheelite powder by combining the action of the circulating material lifting device, so that the scheelite material can be ground multiple times, the scheelite powder can be processed to be finer, and the entire grinding unit can realize multi-stage grinding processing under the action of only one set of grinding mechanism, which effectively meets the pretreatment of scheelite material before normal pressure decomposition and has excellent use effect. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 It is a first angle three-dimensional structure schematic view of the device in the application;

[0026] Figure 2 It is a second angle three-dimensional structure schematic view of the device in the application;

[0027] Figure 3 It is a three-dimensional structure schematic view of the grinding unit in the application;

[0028] Figure 4 It is an internal plane structure schematic view of the grinding unit in the application;

[0029] Figure 5 It is a three-dimensional structure schematic view of the inside of the grinding machine shell;

[0030] Figure 6 It is a front plane structure schematic view of the inside of the grinding machine shell;

[0031] Figure 7The schematic diagram of the conical rotor and the centrifugal sieve plate in the application;

[0032] Figure 8 The schematic diagram of the internal plane structure of the crushing unit in the application.

[0033] Wherein:

[0034] 100-grinding machine shell, 101-crushing machine shell, 102-crushing roller, 103-crushing motor, 104-mineral material hopper, 105-feeding pipe;

[0035] 200-grinding unit, 201-grinding machine shell, 202-power device, 203-grinding block, 204-conical cavity, 205-conical rotor, 206-hollow rotating shaft, 207-receiving groove, 208-expansion block, 209-grinding roller, 210-spring, 211-inclined block, 212-extrusion inclined block, 213-extrusion rod, 214-telescopic driving part, 215-connecting rod, 216-centrifugal sieve plate, 217-circulating material lifting device, 218-bracket, 219-convex ring, 220-receiving hopper, 221-discharging pipe;

[0036] 2021-gearbox, 2022-first gear, 2023-power motor, 2024-second gear;

[0037] 2171-feeding cylinder, 2172-feeding channel, 2173-auger screw blade, 2174-auger motor, 2175-discharging channel;

[0038] 300-conveying unit. DETAILED DESCRIPTION

[0039] In order to make the person skilled in the art better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings in the embodiments. Figures 1-8 The present application will be described in detail below with reference to the drawings in the embodiments.

[0041] Embodiment 1

[0042] The embodiment discloses a pre-processing device for normal-pressure decomposition treatment of scheelite in an alkaline system, referring to the drawings in the embodiments Figure 1 and the drawings in the embodiments Figure 2The processing device comprises a crushing unit 100, a grinding unit 200 and a conveying unit 300, wherein the upper and lower ends of the conveying unit 300 are connected with the grinding unit 200 and the crushing unit 100 respectively, and the conveying unit 300 is used for conveying the preliminarily crushed scheelite to the grinding unit 200 for processing.

[0043] Referring to the accompanying drawings Figure 3 , the accompanying drawings Figure 4 and the accompanying drawings Figure 5 , the grinding unit 200 comprises a grinding shell 201 and a power device 202, a receiving hopper 220 for receiving the scheelite is arranged at the upper surface side end of the grinding shell 201, and a discharging pipe 221 for discharging the scheelite powder after screening is arranged at the lower end of the grinding shell 201.

[0044] A grinding block 203 is fixed on the inner wall of the grinding shell 201, a tapered cavity 204 is arranged on the grinding block 203 along the central axis, and a grinding layer is arranged on the wall surface of the tapered cavity. A circular truncated cone rotor 205 is arranged concentrically in the tapered cavity 204, and a hollow rotating shaft 206 extending out of the grinding shell 201 and connected with the power device 202 is connected to the upper surface of the circular truncated cone rotor 205. The specific power device 202 comprises a gear box 2021 fixed on the upper surface of the grinding shell 201, a first gear 2022 arranged in the gear box 2021 on the hollow rotating shaft 206, a power motor 2023 arranged on the upper surface of the gear box 2021, and a second gear 2024 arranged on the motor shaft of the power motor 2023 and engaged with the first gear 2022. The above-mentioned power device 202 realizes the high-speed rotation of the circular truncated cone rotor 205 in the tapered cavity through the power input of the motor and the meshing transmission between the gears.

[0045] Referring to the accompanying drawings Figure 6 and the accompanying drawings Figure 7 , a plurality of receiving grooves 207 are uniformly arranged on the circumferential side surface of the circular truncated cone rotor 205, an expansion and contraction block 208 is arranged in each receiving groove 207, a grinding roller 209 is rotatably connected to the outer end of the expansion and contraction block 208 extending out of the receiving groove 207, and the grinding roller 209 is arranged parallel to the grinding layer, so that a grinding gap is formed between the two.

[0046] A blind hole is opened in the inner end wall of the receiving groove 207, and a spring 210 connected with the expansion block 208 is arranged in the blind hole. Then, an inner cavity is opened in the center of the grinding block 203 and communicates with the hollow rotating shaft 206. The inner end of each expansion block 208 is connected with an inclined block 211 extending into the inner cavity. An extrusion inclined block 212 is arranged in the inner cavity, and an extrusion inclined surface is arranged on the extrusion inclined block 212 and acts on each inclined block 211. Then, an extrusion rod 213 is rotatably connected to the upper surface of the extrusion inclined block 212, and a telescopic driving element 214 is connected to the top end of the extrusion rod 213 extending out of the hollow rotating shaft 206. When specifically arranged, a support 218 is fixed to the upper surface of the gear box 2021 located directly above the hollow rotating shaft 206, and the telescopic driving element 214 is fixedly arranged at the upper end of the support 218. The telescopic end of the telescopic driving element 214 is connected with the extrusion rod 213. The telescopic driving element 214 can be selected as one of a hydraulic cylinder and a pneumatic cylinder.

[0047] A connecting rod 215 is arranged on the lower surface of the circular table-shaped rotor 205, and the lower end of the connecting rod 215 is connected with a centrifugal sieve plate 216. A circulating material lifting device 217 is fixedly arranged outside the grinding machine shell 201 at the upper surface side end of the centrifugal sieve plate 216, and the upper end of the circulating material lifting device 217 communicates with the upper end of the grinding machine shell 201.

[0048] When specifically arranged, a convex ring 219 extending outward is arranged on the circumferential surface of the grinding machine shell 201 located below the grinding block 203, and the outer circular surface of the centrifugal sieve plate 216 is arranged in abutment with the inner wall of the convex ring 219. The circulating material lifting device 217 includes a vertical fixedly arranged material conveying cylinder 2171, and the lower end of the material conveying cylinder 2171 is provided with a feeding channel 2172. A centrifugal falling opening is opened in the convex ring 219 and communicates with the feeding channel 2172, and the centrifugal falling opening is aligned with the upper surface of the centrifugal sieve plate 216. A auger screw leaf 2173 is arranged in the material conveying cylinder 2171, and the end of the auger screw leaf 2173 is connected with an auger motor 2174. The upper end of the circulating material lifting device 217 is provided with a discharging channel 2175, and the discharging channel 2175 communicates with the upper surface of the grinding machine shell 201.

[0049] Reference is made to the accompanying drawings Figure 1 and the accompanying drawings Figure 8 The crushing unit 100 includes a crusher shell 101, and two crushing rollers 102 are rotatably connected in the crusher shell 101. The end of each crushing roller 102 is connected with a crushing motor 103 arranged on the outer surface of the crusher shell 101. The upper end of the crusher shell 101 is provided with a mineral material hopper 104, and the lower end is provided with a discharging pipe 105 connected with the conveying unit 300. Finally, the conveying unit 300 includes an inclined auger conveyor, and the lower end of the auger conveyor is connected with the discharging pipe 105, and the upper end is provided with a feeding pipe located above the mineral material hopper 104.

[0050] Example 2

[0051] Example 2 discloses a method for decomposing scheelite in an alkaline system under normal pressure, comprising the following steps:

[0052] 1) After being cleaned and impurities removed, the scheelite is put into a crushing unit 100, and then crushed by two crushing rollers 102 to form scheelite fragments.

[0053] 2) The scheelite fragments are then lifted to a receiving hopper 220 by a conveying unit 300, fall through the receiving hopper 220 to the upper surface of a circular table-shaped rotor 205, and then the power device 202 is started to make the circular table-shaped rotor 205 rotate at high speed, and then the scheelite fragments on the upper surface of the circular table-shaped rotor 205 are uniformly thrown outward under the action of centrifugal force, and then fall into the conical cavity 204.

[0054] 3) When the scheelite fragments slide along the wall surface of the conical cavity 204, they are ground under the action of the high-speed rotating grinding roller 209, and the scheelite powder after grinding falls onto the centrifugal sieve plate 216, and then continues to move uniformly outward under the centrifugal action of the centrifugal sieve plate 216, and is screened in the process of movement.

[0055] 4) The scheelite powder that has not been screened is transported to the upper surface of the circular table-shaped rotor 205 by the circulating material lifting device 217 for secondary grinding, and the circulating grinding process is maintained for 15-20 min.

[0056] 5) Next, the telescopic driving part 214 is started to push the extrusion rod 213 downward, and then the extrusion inclined block 212 synchronously pushes the inclined block 211 to make all the expansion blocks 208 move outward against the action of the spring 210, thereby reducing the distance between the grinding roller 209 and the wall surface of the conical cavity 204, and finely grinding the scheelite powder that has not been screened, until all the scheelite powder is screened and collected.

[0057] 6) The sodium phytate and sodium hydroxide are quantitatively added to the deionized water to prepare a leaching agent by stirring, and then the collected scheelite powder is quantitatively added to the leaching agent, and then stirred at a temperature of 90-100°C for 1-2 h, and then solid-liquid separation is performed.

[0058] 7) The above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0059] The above merely preferred embodiments of the present application are not used to limit the present application, any modification, equivalent replacement and improvement etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for decomposing scheelite under normal pressure in an alkaline system, characterized in that, The device used in this method includes a crushing unit (100), a grinding unit (200), and a conveying unit (300), wherein the upper and lower ends of the conveying unit (300) are connected to the grinding unit (200) and the crushing unit (100), respectively. The grinding unit (200) includes a grinding housing (201) and a power unit (202). A grinding block (203) is fixed on the inner wall of the grinding housing (201). A conical cavity (204) is formed along the central axis of the grinding block (203). A grinding layer is provided on the wall of the conical cavity. A frustum-shaped rotor (205) is concentrically arranged in the conical cavity (204). A hollow rotating shaft (206) that extends out of the grinding housing (201) and is connected to the power unit (202) is connected to the upper surface of the frustum-shaped rotor (205). A plurality of storage slots (207) are evenly formed on the circumferential side of the frustum-shaped rotor (205). An expansion block (208) is provided in each storage slot (207). A grinding roller is rotatably connected to the outer end of the expansion block (208) that extends out of the storage slot (207). (209), the grinding roller (209) is arranged parallel to the grinding layer and a grinding gap is formed between them. The inner end wall of the receiving groove (207) is provided with a blind hole. A spring (210) connected to the expansion block (208) is provided in the blind hole. An inner cavity connected to the hollow rotating shaft (206) is provided at the center of the grinding block (203). An inclined block (211) extending into the inner cavity is connected to the inner end of each expansion block (208). An extrusion inclined block (212) is provided in the inner cavity. An extrusion inclined surface that interacts with each inclined block (211) is provided on the extrusion inclined block (212). An extrusion rod (213) is rotatably connected to the upper surface of the extrusion inclined block (212). A telescopic drive (214) is connected to the top end of the extrusion rod (213) extending out of the hollow rotating shaft (206). A connecting rod (215) is provided on the lower surface of the frustum-shaped rotor (205). The lower end of the connecting rod (215) is connected to a centrifugal sieve plate (216). A circulating material lifting device (217) is fixed outside the grinding machine housing (201) located on the side of the upper surface of the centrifugal sieve plate (216). The upper end of the circulating material lifting device (217) is connected to the upper end of the grinding machine housing (201). The power unit (202) includes a gearbox (2021) fixed on the upper surface of the grinding machine housing (201), a first gear (2022) located in the gearbox (2021) is provided on the hollow rotating shaft (206), a power motor (2023) is provided on the upper surface of the gearbox (2021), and a second gear (2024) meshing with the first gear (2022) is provided on the motor shaft of the power motor (2023). The method includes the following steps: 1) The scheelite is added to the crushing unit (100) for initial crushing. After crushing, it is transported to the grinding unit (200) for primary grinding. After primary grinding for a period of time, fine grinding is carried out. At the same time, the ground scheelite powder is centrifuged and screened until all the scheelite powder is screened and collected. 2) Prepare the leaching agent by adding sodium phytate and sodium hydroxide to deionized water in measured amounts and stirring. 3) Add the collected scheelite powder to the leaching agent according to the set amount, and then stir and react for a period of time before performing solid-liquid separation.

2. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 1, characterized in that, The stirring temperature in step 3 is 90-100℃, and the stirring time is 1-2 hours.

3. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 1, characterized in that, A bracket (218) is fixed on the upper surface of the gearbox (2021) located directly above the hollow rotating shaft (206). The telescopic drive (214) is fixedly installed on the upper end of the bracket (218), and the telescopic end of the telescopic drive (214) is connected to the extrusion rod (213).

4. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 1, characterized in that, The grinding machine housing (201) located below the grinding block (203) has an outwardly extending convex ring (219) on its circumferential surface, and the outer circular surface of the centrifugal sieve plate (216) is in contact with the inner wall of the convex ring (219).

5. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 4, characterized in that, The circulating material lifting device (217) includes a vertically fixed conveying cylinder (2171), the lower end of which is provided with a feeding channel (2172). The convex ring (219) is provided with a centrifugal drop port that communicates with the feeding channel (2172) and the centrifugal drop port is aligned with the upper surface of the centrifugal sieve plate (216). The conveying cylinder (2171) is provided with an auger spiral blade (2173), and the end of the auger spiral blade (2173) is connected to an auger motor (2174). The upper end of the circulating material lifting device (217) is provided with a discharge channel (2175), which communicates with the upper surface of the grinding mill housing (201).

6. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 1, characterized in that, The upper surface of the grinding mill housing (201) is provided with a receiving hopper (220) and the lower end is provided with a discharge pipe (221).

7. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 1, characterized in that, The crushing unit (100) includes a crusher housing (101), in which two crushing rollers (102) are rotatably connected. Each crushing roller (102) is connected to a crushing motor (103) on the outer surface of the crusher housing (101) at its end. The upper end of the crusher housing (101) is provided with a ore hopper (104), and the lower end is provided with a feed pipe (105) connected to the conveying unit (300).

8. The method for decomposing scheelite in an alkaline system under normal pressure according to claim 7, characterized in that, The conveying unit (300) includes an inclined auger conveyor, the lower end of which is connected to the feeding pipe (105), and the upper end is provided with a feeding pipe located above the receiving hopper (220).

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