Screw conveyor and method for separating gypsum from paper chips

Abstract

To transport a slip of paper derived from a waste gypsum board with a screw conveyor and separate dihydrate gypsum adhering to the paper slip when the dihydrate gypsum is recovered from the waste gypsum board.CONSTITUTION: A screw conveyor includes: a screw shaft including multiple vanes for sending a transported object in one direction; driving means which rotates the screw shaft; and a casing which encloses the screw shaft. The screw shaft includes a section with no vane provided in an intermediate part as seen in a length direction. A mesh is provided at a bottom part of the casing.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a screw conveyor and a method for separating gypsum from paper chips. [Background technology]

[0002] The inventors have succeeded in industrially recovering gypsum dihydrate from waste gypsum board (Patent Document 1: WO2012 / 176688A). The waste gypsum board is crushed into paper chips and gypsum chips. These are sieved, and the paper chips are recovered as raw material for papermaking, etc. The gypsum chips are heated to convert them into hemihydrate gypsum and / or anhydrous type III gypsum, which is then mixed with gypsum slurry and gypsum dihydrate crystals are precipitated in a crystallization tank. Paper powder is removed from the slurry in which gypsum dihydrate has precipitated using a sieve, and gypsum dihydrate powder is extracted using a solid-liquid separator. The extracted gypsum dihydrate powder is used as raw material for gypsum board, etc.

[0003] Gypsum adheres to the paper fragments that are sieved after crushing. If the paper fragments and gypsum could be further separated, the value of the paper fragments would increase and the recovery rate of gypsum would also improve. However, it is inefficient to set up separate dedicated equipment to remove gypsum that has adhered to the paper fragments.

[0004] Related prior art: Patent Document 2 (Patent 3281340) discloses a device that uses a two-shaft screw conveyor to crush gypsum board and separate it into paper chips and gypsum. Crushing plates are attached to the outer periphery of the screw conveyor blades, and waste gypsum is crushed by being sandwiched between the inner periphery of the casing and the crushing plates. The crushed gypsum falls through holes in the casing, and the paper chips are transported by the screw conveyor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2012 / 176688A [Patent Document 2] Patent 3281340 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to To provide a screw conveyor that can separate foreign matter adhering to an object when transporting the object; This screw conveyor is used to simultaneously transport the paper chips obtained by crushing waste gypsum board and separate the gypsum from the paper chips. [Means for solving the problem]

[0007] The screw conveyor of this invention is a screw shaft having a plurality of blades for feeding the object in one direction; a driving means for rotating the screw shaft; a casing surrounding the screw shaft, The screw shaft has a section in the middle in the longitudinal direction where the blades are not present, A mesh is provided at the bottom of the casing.

[0008] Preferably, a reverse feed blade for conveying the conveyed object in a direction opposite to the one direction is provided in the section.

[0009] In the screw conveyor of this invention, a section without blades is provided, thereby reducing the conveying force acting on the conveyed objects in that section. The conveyed objects are compressed in this section and rub against each other. As a result, any attached matter falls off the conveyed objects and is discharged to the outside of the screw conveyor through a mesh. The screw conveyor of this invention can simultaneously convey the conveyed objects and separate the attached matter. Note that the section without blades means a section without a forward blade that transports the conveyed objects in the forward direction from the inlet to the outlet of the screw conveyor. If a reverse blade that transports the conveyed objects in the opposite direction to the one direction is provided in this section, the forces from the forward blade and the reverse blade will act, causing the conveyed objects to be strongly compressed and rub against each other. This allows for more efficient separation of attached matter.

[0010] In the method for separating gypsum from paper chips of the present invention, when the paper chips obtained by crushing and separating waste gypsum boards are transported by a screw conveyor, Using the screw conveyor, the paper pieces are conveyed; Compressing the paper pieces in the section to separate the gypsum from the paper pieces; The separated gypsum is discharged through the mesh to the outside of the casing.

[0011] In the method for separating gypsum from paper chips of this invention, gypsum can be separated from the paper chips within the screw conveyor that transports the paper chips. This makes it possible to remove gypsum, an impurity in the paper chips, and increase the recovery rate of gypsum without providing any additional dedicated equipment. [Brief explanation of the drawings]

[0012] [Figure 1] Diagram showing the system for recovering gypsum dihydrate from waste gypsum board [Figure 2] Cross-sectional view of a screw conveyor according to an embodiment DETAILED DESCRIPTION OF THE INVENTION

[0013] Examples for carrying out the present invention are shown below. The scope of the present invention should be determined based on the claims, taking into account the description in the specification and well-known techniques in this field, and in accordance with the understanding of those skilled in the art. The scope of the present invention is not limited by the examples. [Example]

[0014] FIG. 1 shows a system 2 for recovering gypsum dihydrate from waste gypsum board, equipped with a screw conveyor 8 of the embodiment. The waste gypsum board is crushed in a crusher 4 such as a crusher or shredder to produce paper chips and gypsum. These are then separated into paper chips that pass through the sieve and gypsum that pass through the sieve using a sieve 6 such as a vibrating sieve. The separated paper chips are transported by a screw conveyor 8, and as they are transported, any gypsum adhering to them is separated from them. The paper chips from which the gypsum has been removed become raw material for papermaking, etc.

[0015] The gypsum separated by the screw conveyor 8 is heated in a heater together with the gypsum that falls below the sieve to form hemihydrate and / or anhydrous type III gypsum, which is then mixed with the gypsum slurry in a mixer. Gypsum dihydrate crystals are precipitated from the slurry in a crystallization tank 14, and paper powder in the slurry is removed using a sieve such as a vibrating sieve 16. The slurry is then processed in a solid-liquid separator 18 such as a filter press to extract gypsum dihydrate powder, and the slurry is returned to the mixer 12 or the like.

[0016] Figure 2 shows the structure of the screw conveyor 8. The screw conveyor 8 slopes upward from the inlet 27 to the outlet 28, with the dashed lines at the bottom of the figure indicating the horizontal and vertical directions. A rotating shaft 20 is mounted along the central axis of a cylindrical casing 26 and is rotated by a drive source 24 such as a motor. The rotating shaft 20 is equipped with forward-feeding blades 21 on both the inlet 27 side and the outlet 28 side, and transports the paper pieces in a forward direction from the inlet 27 to the outlet 28 side. The intermediate compression section 25 does not have forward-feeding blades 21; instead, it is equipped with reverse-feeding blades 22, which apply a transport force to the paper pieces toward the inlet 27 side. Furthermore, a mesh 30 consisting of numerous openings is provided at the bottom and lower side periphery of the casing 26 in and on both sides of the compression section 25.

[0017] The compression section 25 may simply have the rotating shaft 20 passing through it without providing either the forward blade 21 or the reverse blade 22. Also, instead of the reverse blade 22, the compression section 25 may be provided with a restrictor or baffle plate or the like that restricts the movement of the paper pieces.

[0018] The pieces of paper fed through the inlet 27 are transported by the forward blade 21 to the right side of the figure (diagonally upward in the actual machine). In the compression section 25, the reverse blade 22 acts, compressing the pieces of paper and causing them to rub against each other, peeling off the gypsum from the pieces of paper. Even without the reverse blade 22, the propulsive force from the forward blade 21 is reduced, and gravity and friction with the casing 26 (for example, friction with the mesh 30) act as resistance, slowing the movement speed of the pieces of paper. This causes the pieces of paper to be compressed and the gypsum to peel off. If a restrictor, baffle, etc. is provided, stronger compression and frictional forces act on the pieces of paper. The gypsum peeled off from the pieces of paper falls through the mesh 30 near the bottom of the casing 26, and the pieces of paper are discharged from the outlet 28.

[0019] Preferably, an auxiliary screw conveyor 32 is provided below the mesh 30. A rotating shaft 34 is provided in the center of a cylindrical casing 40 and rotated by a drive source 40 such as a motor. Furthermore, feed blades 35 and 36 are attached to the rotating shaft 34 so as to transport the gypsum to an outlet 42 provided in the middle of the casing 40. Because the outlet 42 is located in the middle of the casing 40, the feed blades 35 and 36 have opposite transport directions. In this way, the gypsum that falls from the mesh 30 is transported and discharged from the outlet 42. Note that if the outlet 42 is located at either end of the casing 40, the gypsum is transported in one direction, and only one type of feed blade needs to be provided.

[0020] The screw conveyor 8 of the embodiment can simultaneously transport the paper pieces and remove the gypsum adhering to the paper pieces, thereby increasing the value of the paper pieces taken out from the outlet 28 and increasing the recovery rate of the gypsum.

[0021] In this embodiment, the paper pieces and gypsum are separated by the screw conveyor 8. However, the screw conveyor 8 can be used for general purposes, such as simultaneously transporting a sheet-like object having foreign matter attached thereto and separating the attached matter. [Explanation of symbols]

[0022] 2. Gypsum recovery system 4 Crusher 6 sieve 8. Screw Conveyor 10 Heating machine 12 Mixer 14 Crystallization tank 16 Sieve 18 Separation device 20 Rotation axis 21 Progressive blade 22 Reverse feed vane 24 Drive source 25 Compression Section 26 Casing 27 Inlet 28 Exit 30 mesh 32 Auxiliary screw conveyor 34 Rotation axis 35,36 Feed blade 38 Power Source 40 Casing 42 Exit

Claims

1. A screw conveyor that conveys objects and separates foreign matter adhering to the objects, a screw shaft having a plurality of blades for feeding the object in one direction; a driving means for rotating the screw shaft; a casing surrounding the screw shaft, The screw shaft has a section in the middle in the longitudinal direction where the blades are not present, A mesh is provided at the bottom of the casing, Furthermore, a reverse feed blade is provided in the section where there is no blade, which conveys the conveyed object in a direction opposite to the one direction, the mesh is provided so as to correspond to the reverse feed blade and the blades for feeding the conveyed object in the one direction on both sides thereof, but not to correspond to a part of the blades for feeding the conveyed object in the one direction; a second screw conveyor for conveying the foreign matter discharged through the mesh and a second casing surrounding the second screw conveyor are provided at the bottom of the casing in the section where the mesh is provided; the second casing has an outlet for foreign objects at a midpoint in the conveying direction of the second screw conveyor; The second screw conveyor is a screw conveyor equipped with two types of blades with opposite conveying directions on both sides of the outlet for the foreign objects.

2. 2. The screw conveyor according to claim 1, wherein blades for transporting the conveyed objects in one direction are provided on both sides of the section where no blades are present.

3. 3. The screw conveyor according to claim 1, wherein the screw shaft is oriented obliquely upward from the inlet to the outlet of the conveyed objects.

4. When transporting the paper pieces obtained by crushing and separating waste gypsum boards using a screw conveyor, The paper pieces are transported using the screw conveyor according to any one of claims 1 to 3, Compressing the paper pieces in the section where there are no blades separates the gypsum from the paper pieces; The separated gypsum is poured through the mesh into the second casing and discharged from the foreign matter outlet by the second screw conveyor. How to separate gypsum from paper strips.

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