JP2012086130A - Drum type granulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum type granulator that requires less maintenance frequency and keeps adhesion prevention effects to an object to be adhered over a long period of time.SOLUTION: The drum type granulator includes a rotary drum. The granulator is provided for producing, within the drum, a granular substance from a raw material mixture of an iron oxide-containing material and a carbonaceous material. The drum type granulator is characterized in that a rubber sheet containing 90 mass% or more of natural rubber is arranged on the inner wall of the rotary drum.

Description

  The present invention relates to a drum type granulator that forms a granular material from a mixed raw material of an iron oxide-containing material and a carbonaceous material.

  A conventional drum type granulator rotates a drum that is horizontally arranged or slightly inclined, supplies powder raw material from one side of the drum, and discharges pellets granulated in the drum from the other side. Is configured to do. This type of drum granulator is equipped with a scraper device for limiting the thickness of deposits adhering to the inner wall of the drum (see, for example, Non-Patent Document 1).

  As another device for restricting the deposits on the drum, there is also known a device in which a rubber lining is provided along the inner wall of the drum. In this device, a sheet-like rubber lining is attached to the inner wall of the drum with a presser foot that is airtight at both ends of the drum and at a few points on the circumferential wall of the drum cylinder, and is substantially parallel to the drum shaft. The formation of deposits is prevented by utilizing the wavy motion of the lining (see, for example, Patent Document 1).

  The above-mentioned wave motion means that the rubber lining moved to the upper side of the drum hangs down by its own weight with the rotation of the drum to drop off the adhering matter, and the rubber lining moved to the bottom side of the drum is supplied into the drum. This means that the operation of contacting the drum with the weight of the raw material is repeated.

  When a rubber lining is used, a breathing hole is provided in the drum body on the back side of the rubber lining to facilitate the deformation and return of the rubber lining.

Japanese Patent Publication No. 45-7962

“Granulation Handbook”, published by OHM Co., Ltd., published on March 10, 1991, p. 148-149

  However, the former scraper device in the drum type granulator has a durable structure that can withstand the force applied when scraping off the deposits adhering to the inner wall of the drum, and a mechanism for adjusting the gap between the tip of the scraper and the inner wall of the drum. In addition, the scraper tip inevitably wears due to deposits, so there are disadvantages that the cost and maintenance cost are high, and there is a problem that it is difficult to adjust the gap between the scraper and the drum inner wall.

  On the other hand, the latter drum-type granulator uses elastic deformation of the rubber lining to prevent deposits from adhering, so that it is not necessary to provide an operating mechanism like the scraper device of the former drum-type granulator. There is an advantage that it is cost and adjustment is unnecessary. However, there is a problem that the life of the rubber lining is short and the rubber lining must be periodically replaced.

  The present invention has been made in consideration of the problems in the conventional drum type granulator as described above, and is a drum type that can maintain the adhesion preventing effect of deposits over a long period of time without the need for frequent maintenance. A granulator is provided.

  As a result of intensive studies to solve the above problems, the present inventors have found the following facts.

  Synthetic rubber is used in a conventional drum type granulator using a rubber lining. This is because synthetic rubber is generally excellent in wear resistance, cold resistance, heat resistance, weather resistance, and chemical resistance. However, as a result of careful investigation by the present inventors, when the drum type granulator was used for a long period of time, the surface of the rubber sheet was likely to be rough, and minute cracks were likely to occur.

  Therefore, the mixed raw material charged into the drum type granulator tends to grow greatly starting from the cracked part, and causes a large amount to adhere to the rubber sheet.

  Accordingly, the present inventors examined the adhesion of the mixed raw material using various rubber sheets having flexibility so as to replace the conventional rubber sheet. As a result, natural rubber (NR: JIS-K-6397) was obtained. ) Was most suitable, and the present invention was completed.

  That is, the drum-type granulator of the present invention that has solved the above-described problems has a rotating drum, and a drum-type granulator that forms a granular material from a mixed raw material of iron oxide-containing material and carbonaceous material therein In addition, a rubber sheet (hereinafter, “natural rubber sheet”) containing 90% by mass or more of natural rubber (NR: JIS-K-6397) is disposed on the inner peripheral wall of the rotating drum.

  Since natural rubber contains double bonds in the main chain, it is susceptible to ozone attack in the atmosphere and is generally considered not to be particularly excellent in durability and weather resistance. However, according to the study by the present inventors, it has been surprisingly found that the surface of the natural rubber sheet is kept smooth. Therefore, even if the drum type granulator of the present invention is used for a long time, the mixed raw material hardly adheres to the surface of the natural rubber sheet, and the mixed raw material hardly grows.

  In the drum granulator, the natural rubber sheet is preferably airtightly fixed to the rotating drum at at least one end of the rotating drum.

  In the drum type granulator, the natural rubber sheet is preferably fixed by a pressing member whose longitudinal direction is substantially parallel to the rotation axis of the rotary drum.

  In the drum type granulator, it is preferable that a breathing hole is provided in a body portion of the rotating drum.

  When the above-mentioned drum type granulator is used in a mode in which an organic binder is contained in the granular material, the significance of using the natural rubber sheet in the present invention is further increased.

  According to the drum type granulator of the present invention, since the natural rubber sheet is arranged on the inner wall of the body part of the rotating drum, the smoothness of the natural rubber sheet surface is maintained even when the drum type granulator is used for a long period of time. Be drunk. Therefore, the mixed raw material hardly adheres to the surface of the natural rubber sheet and is difficult to grow. Therefore, the maintenance frequency of the drum granulator can be reduced, and the adhesion preventing effect of deposits can be maintained for a long time.

(a) is a side view showing a drum structure of a drum type granulator according to the present invention, and (b) is a longitudinal sectional view taken along the line AA ′ of FIG. It is the B section enlarged view of Fig.1 (a).

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

  The drum type granulator of the present invention forms a granular material from a mixed raw material of an iron oxide-containing material and a carbonaceous material inside a rotating drum.

  FIGS. 1A and 1B show the structure of the rotating drum (hereinafter abbreviated as drum).

  In both figures, the drum 1 has a cylindrical main body 2, and a ring portion is provided around each end in the cylinder axis direction on the outer wall of the main body 2. The drum 1 is rotatably supported by supporting each ring portion with a pair of rollers (not shown).

  A natural rubber sheet 3 is attached to the inner wall of the body part 2.

  The natural rubber sheet 3 is formed by forming natural rubber into a sheet shape having a thickness of 4 mm to 9 mm, preferably 5 mm to 8 mm, more preferably 6 mm to 7 mm. The natural rubber sheet 3 has a cylindrical shape along the body inner wall 1 a of the drum 1. Is provided.

  In this embodiment, when the drum 1 is viewed from the side, the natural rubber sheet 3 is fixed by the presser member 4 at nine positions at a pitch of 40 ° (circumferential angle) in the circumferential direction.

  The presser member 4 is made of a band plate-like member, and is attached to the barrel inner wall 1 a over the substantially entire length of the drum 1. Thereby, both ends of the natural rubber sheet 3 in the circumferential direction are restrained by the presser members 4, and the range between the adjacent presser members 4 is free.

  Moreover, about each edge part of the longitudinal direction of the natural rubber sheet 3, it is being fixed to the trunk | drum inner wall 1a over the perimeter.

  Therefore, the natural rubber sheet 3 is configured to perform a wave-like motion with the rotation of the drum 1 in a range other than the portion fixed by the pressing member 4 or the like. Specifically, as the drum 1 rotates, the natural rubber sheet 3 that has moved to the upper side of the drum 1 hangs down by its own weight to drop off the adhering matter, and the natural rubber sheet 3 that has moved to the bottom side of the drum 1 has The operation of contacting the drum with the weight of the raw material supplied into the drum 1 is repeated.

  Further, the natural rubber sheet 3 is airtightly fixed to the drum 1 at both ends of the drum 1, but it is sufficient that the natural rubber sheet 3 is airtightly fixed to the drum 1 at least at one end.

  A breathing hole 5 having a diameter of 70 mm to 120 mm is disposed at a substantially intermediate position in the circumferential direction of each pressing member 4.

  In the present embodiment, four breathing holes 5 are also provided in the cylinder axis direction of the drum 1 so that the natural rubber sheet 3 partitioned by the pressing member 4 can be smoothly deformed (wave-like motion). It has become.

  That is, for the natural rubber sheet 3 that has moved to the bottom of the drum 1 as the drum 1 rotates, the drum of the natural rubber sheet 3 and the drum 1 is brought into close contact with the barrel inner wall 1 a by the raw material supplied into the drum 1. As for the natural rubber sheet 3 that quickly exhausts air between the inner wall 1a and moves to the upper part of the drum 1, the natural rubber sheet 3 and the inner wall 1a of the drum 1 are separated from the inner wall 1a by its own weight. The air is quickly taken in from the outside of the drum 1 so that the space between and does not become a negative pressure state (see FIG. 2).

  The natural rubber sheet 3 contains 90% by mass or more of natural rubber (NR: JIS-K-6397), and the balance of the natural rubber sheet is butyl rubber (IIR), isoprene rubber (IR), ethylene propylene rubber. (EPM, EPDM), butadiene rubber (BR), urethane rubber (U), styrene butadiene rubber (SBR), silicone rubber (Q), chloroprene rubber (CR), chlorosulfonated rubber (CSM), acrylonitrile butadiene rubber (NBR) ), Chlorinated polyethylene (CM), acrylic rubber (ACM), epichlorohydrin rubber (CO, ECO), fluorine rubber (FKM), etc., but is not particularly limited.

  As described above, the natural rubber sheet contains 90% by mass or more of natural rubber (NR), preferably 95% by mass or more, and more preferably 98% by mass or more.

  The natural rubber sheet maintains the surface smoothness even when used for a long time, so that the mixed raw material hardly adheres to the surface, and the mixed raw material hardly grows.

  Natural rubber is obtained by coagulating and drying a sap (latex) of a rubber tree. Natural rubber is a substance mainly composed of cis-1,4-polyisoprene, and its chemical structure is represented by the following structural formula (1).

  Natural rubber contains a slight amount of trans, but unlike synthetic rubber, 99% or more is cis-type polyisoprene. Natural rubber contains trace amounts of proteins and fatty acids, but synthetic polyisoprene does not contain such impurities.

Drum inner diameter: 2,690mm
Natural rubber sheet thickness: 6.4mm
Fixing bracket mounting interval (circumferential angle): 40 °
Breathing hole diameter: 80mm
Arrangement density of breathing holes: 0.4 to 0.95 / m ²
Breathing hole drum axial distance: 1525-2847 mm
Specification of natural rubber sheet Number of core canvas plies (2 layers): 1.6mm
Cover material: natural rubber Top cover thickness: 2.4 mm
Lower cover thickness: 2.4mm

  As a result of trial run of a drum type granulator having a natural rubber sheet lined based on the above specifications, it was not necessary to perform maintenance frequently, and the effect of preventing adhesion of deposits could be maintained for at least 100 days.

1 drum (rotating drum)
1a Body inner wall 2 Body portion 3 Natural rubber sheet 4 Presser member 5 Breathing hole

Claims (4)

A drum-type granulator that has a rotating drum and forms granular material from a mixed raw material of iron oxide-containing material and carbonaceous material,
A drum type granulator characterized in that a rubber sheet containing 90% by mass or more of natural rubber is arranged on the inner peripheral wall of the rotating drum.   The drum type granulator according to claim 1, wherein in the drum type granulator, the natural rubber sheet is airtightly fixed to the rotary drum at at least one end of the rotary drum.   The drum type granulator according to claim 1 or 2, wherein the natural rubber sheet is fixed by a pressing member whose longitudinal direction is substantially parallel to a rotation axis of the rotary drum.   The drum type granulator according to any one of claims 1 to 3, wherein a breathing hole is provided in a body portion of the rotary drum.