JP7644576B2 - Rotary stirring type heat treatment device - Google Patents

Description

The present invention relates to a rotary agitation type heat treatment device that applies agitation heat treatment to a workpiece and a heat treatment method using the device.

A rotary agitation type heat treatment device is used to perform various heat treatments on objects to be treated. This rotary agitation type heat treatment device introduces the objects to be treated into a rotating cylindrical furnace, and performs heat treatment on the objects to be treated while moving them from the upstream to the downstream of the furnace by the rotation of the cylindrical furnace.
On the other hand, the purpose of this heat treatment varies depending on the object to be treated, and examples of such purposes include calcination for lime, mixing for electrode materials, and oxidation for metal powder.

Various proposals have been made to make the heat treatment more effective in this rotary stirring type heat treatment device.

For example, Patent Document 1 describes a rotary stirring type heat treatment device having a beater member that rolls on the inner circumference of a rotating furnace tube to impart an impact to the workpiece, and the rolling beater member is said to impart an impact to the workpiece, preventing the workpiece from adhering to the inner circumference of the furnace tube.

For example, Patent Document 2 describes a rotary stirring type heat treatment device that has a rotor with three or four blades inside a rotating furnace tube, where L is the length of the rotor blades and R is the inner diameter of the furnace tube, and where L/R is 0.1 to 0.6, and is said to be capable of oxidizing electrolytic copper powder to cupric oxide powder.

JP 2012-163282 A Patent No. 6056709

The rotary agitation type heat treatment device described in Patent Document 1 is intended for heat treatment of lime-based objects measuring 5 mm or less, and the rotary agitation type heat treatment device described in Patent Document 2 is intended for heat treatment of electrolytic copper powder. As such, if the object to be treated is a powder or a small object close to powder in size, the heat treatment devices described in Patent Documents 1 and 2 can perform the heat treatment as described. However, Patent Documents 1 and 2 do not describe the heat treatment of lumpy objects, and the inventor's investigation revealed that although these rotary agitation type heat treatment devices have beater members or rotors, it is difficult to perform sufficient heat treatment when actually performing heat treatment on lumpy objects.

The object of the present invention is to provide a rotary stirring type heat treatment device capable of reliably performing heat treatment on bulk objects to be treated, and a heat treatment method using said device.

The present inventors have conducted extensive research into the structure of a rotary stirring type heat treatment apparatus capable of heat treating even lump-shaped objects, such as lump scrap containing tungsten (W), for which there has been a demand in recent years for cheap and reliable recycling, that do not pass through a sieve with a mesh size of 5 mm, but pass through a sieve with a mesh size of 30 mm.
Here, sieves with mesh sizes of 5 mm and 30 mm refer to sieves having square mesh sizes with sides measuring 5 mm and 30 mm, respectively.

As a result, we have gained the novel insight that reliable heat treatment is possible if a cylinder (furnace tube) is divided in the inner circumferential direction and multiple treatment zones are provided along the longitudinal direction of the cylinder, and these treatment zones rotate with the rotation of the cylinder, and the chunks of material supplied to each treatment zone are prevented from migrating (moving) to other treatment zones, so that the material is heat-treated while being stirred, crushed, and sized.

The present invention is based on this finding and is as follows.
"(1) A rotary stirring type heat treatment device for heat-treating a workpiece,
the material to be treated is a lump-shaped scrap containing tungsten of a size that does not pass through a sieve having square openings with a side length of 5 mm, but passes through a sieve having square openings with a side length of 30 mm,
a heat treatment section having a cylindrical body into which the workpiece is fed from one end, heat-treated therein, and discharged from the other end;
A heating means for heating the inside of the cylindrical body;
a treatment zone forming means for forming a plurality of treatment zones inside the cylinder, the treatment zones being divided in an inner circumferential direction of the cylinder and arranged along a longitudinal direction of the cylinder;
The treatment zone forming means is a radiblade having a cylindrical portion at its center and a plurality of blades provided at equal intervals on the outer periphery of the cylindrical portion,
The ruddy blade rotates while swinging due to the rotation of the cylindrical body,
The ruddy blade has a structure in which, when the ruddy blade is placed at the center of the cylinder, the distance between the tip of the blade and the inner circumference of the cylinder is M and the inner diameter of the cylinder is D, the M/D ratio is 0.01 to 0.10, and the material supplied to each of the treatment zones is allowed to move to another treatment zone by 10% by volume or less,
In each of the treatment zones, the material to be treated is oxidized at 850 to 900° C. while being stirred, crushed, and sized ;
A rotary stirring type heat treatment device characterized by the above.
( 2 ) The rotary stirring type heat treatment device according to (1), characterized in that the number of the blades of the ruddy blade is 8 to 16 , and the proportion of the cross-sectional area of the cylindrical portion in the radial cross section of the cylindrical body is 25 to 35%.
( 3 ) A method for heat treating an object to be treated, comprising using the rotary stirring type heat treatment device according to (1) or (2) above.

The rotary stirring type heat treatment device of the present invention is particularly capable of reliably heat treating lumpy objects, and the heat treatment method of the present invention is a method for reliably heat treating the same lumpy objects.

1 is a schematic cross-sectional view of an example of a rotary stirring type heat treatment apparatus of the present invention. FIG. 2 is a schematic cross-sectional view of an example of a treatment zone forming means. FIG. 11 is a schematic cross-sectional view of another example of the treatment zone forming means. FIG. 11 is yet another schematic cross-sectional view of the treatment zone forming means. FIG. 5 is a schematic perspective view of the treatment zone forming means of FIG. 4. FIG. 5 is a schematic diagram for explaining the distance between the processing zone forming means in FIG. 4 and the inner circumference of the cylinder. FIG. 7 is an enlarged view of the circled portion in FIG. 6 .

Below, we will explain an embodiment of the present invention for heat treating a block of workpiece with reference to the drawings, but the present invention is not limited to the following embodiment.

In this specification, the term "lump material to be treated" refers to a mass material that does not pass through a 5 mm sieve but passes through a 30 mm sieve (in the case of a mass material that does not pass through the 30 mm sieve, which has been crushed, it may unintentionally include masses that pass through the 5 mm sieve resulting from the crushing), and examples of heat treatment of the mass material include oxidation treatment in the air (in an oxidizing atmosphere) using metals such as titanium, molybdenum, chromium, copper, etc. as the mass material, and firing treatment using industrial waste such as scrap as the mass material.

A rotary stirring type heat treatment apparatus 1 according to an embodiment of the present invention shown in Fig. 1 has, from upstream to downstream, a supply section 2, a heat treatment section 3, and a discharge section 4. In Fig. 1, a treatment zone forming means provided in the heat treatment section 3 is not shown.

The supply section 2 has, for example, a hopper 21 and a screw conveyor 22 (detailed configuration not shown). Agglomerated workpieces to be heat-treated, for example, agglomerated scrap containing tungsten, are stored in the hopper 21, and a predetermined amount of the stored agglomerated workpieces is supplied to the heat treatment section 3 by the screw conveyor 22.

The discharge section 4 has a discharge means 41 that discharges the chunks of material that have been heat-treated in the heat treatment section 3 out of the rotary stirring type heat treatment device 1. There are no particular restrictions on the structure of this discharge means 41, so long as it is capable of discharging the chunks of material that have been heat-treated, and any known means may be used as appropriate.

The heat treatment section 3 has a cylinder (furnace tube) 31 that rotates by a means not shown. The cylinder 31 is inclined so that one end (the side having the supply section 2, upstream) is higher than the other end (the side having the discharge section 4, downstream) relative to a stand not shown. In other words, the height of the cylinder 31 is lower on the discharge section 4 side than on the supply section 2 side. A processing zone forming means 5 is provided inside the cylinder 31, and as described below, the processing zone forming means 5 rotates while swinging due to the rotation of the cylinder 31, and the lumpy processed material supplied from the supply section 2 is heat-treated while being stirred, crushed, and sized (details will be described in the explanation of the processing zone forming means 5), and moves toward the discharge section 4. Then, when the lumpy processed material arrives at the end of the cylinder 31 on the discharge section 4 side, it falls into the discharge section 4 and is discharged outside the rotary stirring type heat treatment device 1 by the discharge means 41.

In addition, the heat treatment section 3 is provided with a heater, for example, a resistance heater, as a heating means for heating the block of workpieces (not shown), and the inside of the cylinder 31 is heated to a predetermined temperature by generating heat from the heater. A predetermined gap is provided between the cylinder 31 and the heater so that the cylinder 31 can rotate.

A processing zone forming means 5 is provided inside the cylinder 31, which is divided in the inner circumferential direction of the cylinder 31 and forms multiple processing zones 6 along the longitudinal direction of the cylinder. The processing zone forming means 5 has a structure (specific structure will be described later) that prevents the chunks of material supplied to each of the multiple processing zones 6 from moving to other processing zones 6 while being heat-treated by the rotary stirring type heat treatment device 1, and has a structure that rotates while swinging due to the rotation of the cylinder 31. Here, preventing the chunks of material from moving does not mean that the chunks of material do not move at all, but means that a maximum of about 10% by volume of the chunks of material in each processing zone 6 is allowed to move.

The reason for the above-mentioned structure of the processing zone forming means 5 will be explained. In the processing zone forming means 5 such as the beater member described in the above-mentioned Patent Document 1 and the rotor described in the same Patent Document 2, the processing zone forming means 5 rotates while oscillating due to the rotation of the cylinder of the rotary stirring type heat treatment device, but the movement of the lumpy processed material in each processing zone 6 to other processing zones 6 during heat treatment is not prevented. Therefore, the oxidized lumpy processed material covers the lumpy processed material that has not been oxidized by the heat treatment, and when the lumpy processed material is viewed as a whole, unoxidized parts remain, making it difficult to perform uniform heat treatment. This is to prevent this.

An example of the processing zone forming means 5 cut along a radial cross section of the cylinder 31 is shown diagrammatically in Figures 2 to 5.

As is clear from the figures, the processing zone forming means 5 shown in Figures 2 and 3 has a cylindrical portion 7, which is a cylindrical cavity in the center, and processing zones 6 around it, and rotates while oscillating due to the rotation of the cylinder 31, and the outer edges of each processing zone 6 are isolated from each other, so that the chunks of material supplied to each processing zone 6 are prevented from moving to other processing zones 6 while being heat-treated by the rotary stirring type heat treatment device 1 (they do not move).

The treatment zone forming means 5 shown in Fig. 4 uses a ruddy blade, and a schematic perspective view of the ruddy blade is shown in Fig. 5. As is clear from these figures, the ruddy blade has a cylindrical portion 7 at its center, and a plurality of blades are provided at equal intervals on the outer periphery of this cylindrical portion 7 to form a treatment zone 6.

The number of radii blades shown in FIG. 4 is eight, but the object of the present invention can be achieved with two radii blades, and the object of the present invention can be achieved more reliably with three to sixteen radii blades, and is preferably further achieved with four to eight radii blades.

As mentioned above, it is more preferable to adjust the distance between the tip of the blade of the ruddy blade and the inner circumference of the cylinder 31 in order to prevent the chunky treated material supplied to each treatment zone 6 from moving to another treatment zone 6 during heat treatment. For chunky treated material, for example, as shown in Figures 6 and 7, when the center of the cylindrical part of the ruddy blade is aligned with the center of the cylinder, the distance between the tip of the blade of the ruddy blade and the inner circumference of the cylinder is M, and the inner diameter of the cylinder is D, it is more preferable that M/D is 0.01 to 0.10 (1 to 10%).

The reason for this is that when it is in this range, the oscillating rotation of the ruddy blade caused by the rotation of the cylinder stirs, breaks, and straightens out the lumpy material while it is being heat-treated, and the lumpy material supplied to each treatment zone 6 is more reliably prevented from moving to other treatment zones 6. And when the heat treatment is for the purpose of oxidation treatment, an M/D of 0.01 to 0.10 (1 to 10%) further improves the oxidation rate.

When the processing zone forming means 5 is a ruddy blade, the processing zone forming means 5 may be one from the upstream to downstream of the cylinder 31, or multiple processing zone forming means 5 of the same shape, for example, four, may be provided. In this case, each processing zone forming means 5 rotates almost synchronously. Therefore, in adjacent processing zone forming means 5, the chunks of material to be processed in each processing zone 6 of the upstream processing zone forming means 5 are transferred to each processing zone 6 of the downstream processing zone forming means 5 by the rotation of the tilted cylinder 31.

In addition, when considering the ease of maintenance of the equipment, when the treatment zone forming means 5 is a radiblade, it is preferable to provide multiple treatment zone forming means 5 of the same shape rather than providing a single treatment zone forming means 5 from the upstream to downstream of the cylinder 31 (in the longitudinal direction of the cylinder 31). In other words, each treatment zone forming means 5 is lighter and easier to handle, and in the event of damage, only the corresponding treatment zone forming means 5 needs to be replaced.

Here, the mechanism by which the processing zone forming means 5 shown in Figures 2 to 5 rotates while swinging due to the rotation of the cylinder 31 will be described. First, the processing zone forming means 5 rotates slightly in the same direction as the rotating body 31 in association with the rotation of the cylinder 31. That is, due to the rotation of the rotating body 31, the processing zone forming means 5 rotates slightly while the tip of the processing zone forming means 5 is in contact with the inner circumference of the cylinder 31. Then, when this rotational movement is performed by a predetermined amount, the center of gravity of the processing zone forming means 5 shifts, and the tip of another processing zone forming means 5 that was not in contact with the inner circumference of the cylinder 31 until then comes into contact with the inner circumference of the cylinder 31, and the processing zone forming means 5 rotates with swinging. By continuing to change the tip of the processing zone forming means 5 that is in contact with the inner circumference of the cylinder, the processing zone forming means 5 rotates while swinging in the same direction as the cylinder 31 at a different rotational speed than the cylinder 31.

By rotating and oscillating the processing zone forming means 5, the chunks of material to be processed supplied to each processing zone 6 formed by the processing zone forming means 5 are agitated, crushed, and sized in each processing zone 6, and are efficiently heat-treated.

It is preferable to supply approximately the same amount of lumpy material to each processing zone 6. This is because the lumpy material in each zone can be evenly exposed to the atmosphere inside the cylinder 31, and the rotation of the processing zone forming means 5 is uniform, so that the lumpy material can be more reliably agitated within the processing zone 6.

2 to 5, the area indicated as cylindrical portion 7 is not the treatment zone 6, and no lumpy material is supplied thereto. The proportion of the cross-sectional area of the cylindrical portion 7 in the radial cross section of the cylinder 31 is preferably 25 to 35%. The reason for this is that within this range, the movement of the lumpy material in the center of the cylinder 7 can be reliably suppressed, ensuring high production efficiency. However, when the treatment zone forming means 5 is a ruddy blade and the number of blades is three or less, the proportion of the cross-sectional area of the cylindrical portion 7 is not particularly specified, so long as the ruddy blade can ensure the mechanical strength required for the treatment zone forming means 5.

It goes without saying that the present invention includes any processing zone forming means 5 having a shape other than those shown in these figures, so long as it is configured to prevent the movement of the lumpy material to other processing zones 6 during heat treatment due to the rotation of the cylindrical body 31 of the rotary stirring type heat treatment device 1.

The following is a detailed description of one embodiment of the rotary stirring type heat treatment device of the present invention, but the present invention is not limited to this embodiment.

Scrap containing tungsten (WC-Co scrap (mass ratio of WC to Co is 9:1)) was used as the lump-shaped material to be treated. This scrap was crushed. Then, this scrap was heat-treated using a rotary stirring type heat treatment device 1 in which the treatment zone forming means 5 is a ruddy blade. The results (Examples 1 to 8) are shown in Table 1.

In contrast, for comparison, the same scrap as in Examples 1 to 8 was used as the lump-shaped treated material, and heat treatment was performed using a rotary stirring type heat treatment device that did not have a treatment zone forming means 5 (Comparative Example 1), and a rotary stirring type heat treatment device that had a ruddy blade as the treatment zone forming means 5 but did not prevent the lump-shaped treated material in each treatment zone from moving to another treatment zone (Comparative Examples 2 to 4) . The results are shown in Table 2.

In Tables 1 and 2, the supply amount, processing temperature, and processing time are the same, and only the presence or absence of a processing zone forming means, or the presence or absence of suppression of the movement of the lumpy processing material, are different. Here, the supply amount is the amount of scrap supplied, the processing temperature is the maximum and minimum temperatures of the cylinder of the rotary stirring type heat treatment device, and the processing time is the residence time of the scrap inside the cylinder. Also, the gap refers to the value of M/D (expressed as a percentage) when M is the distance between the tip of the ruddy blade blade and the inner circumference of the cylinder, as mentioned above, and D is the inner diameter of the cylinder.

The mass increase rate (%) is
[(mass after heat treatment)/(mass before heat treatment)×1.19}]×100
and corresponds to the oxidation rate.
Note that 1.19 is the mass ratio before and after oxidation when WC-Co scrap (whose mass ratio is 9:1 between WC and Co) is completely oxidized to produce WO ₃ , CoWO ₄ and CO ₂ .

As is clear from Tables 1 and 2, in all of Examples 1 to 8, the migration of the aggregates in each processing zone to other processing zones was suppressed, so that the mass increase rate was high and the oxidation process was carried out efficiently. In contrast, Comparative Example 1 did not have a ruddy blade, and the agglomerates were not stirred, crushed, or sized sufficiently, and Comparative Examples 2 to 4 did not suppress the migration of the aggregates in each processing zone to other processing zones, so that the mass increase rate was low and it was confirmed that the oxidation process was not carried out sufficiently.

The present invention is particularly capable of efficiently performing heat treatment on block objects, and can provide a satisfactory solution for energy saving and cost reduction in heat treatment.

1 Rotary stirring type heat treatment device 2 Supply section 21 Hopper 22 Screw conveyor 3 Heat treatment section 31 Cylinder (furnace tube)
4 Discharge section 41 Discharge means 5 Treatment zone forming means 6 Treatment zone 7 Cylindrical section D Inner diameter of cylinder M Distance between the tip of the blade of the ruddy blade and the inner circumference of the cylinder

Claims (3)

A rotary stirring type heat treatment device for heat-treating a workpiece, comprising:
the material to be treated is a lump-shaped scrap containing tungsten of a size that does not pass through a sieve having square openings with a side length of 5 mm, but passes through a sieve having square openings with a side length of 30 mm,
a heat treatment section having a cylindrical body into which the workpiece is fed from one end, heat-treated therein, and discharged from the other end;
A heating means for heating the inside of the cylindrical body;
a treatment zone forming means for forming a plurality of treatment zones inside the cylinder, the treatment zones being divided in an inner circumferential direction of the cylinder and arranged along a longitudinal direction of the cylinder;
The treatment zone forming means is a radiblade having a cylindrical portion at its center and a plurality of blades provided at equal intervals on the outer periphery of the cylindrical portion,
The ruddy blade rotates while swinging due to the rotation of the cylindrical body,
The ruddy blade has a structure in which, when the ruddy blade is placed at the center of the cylinder, the distance between the tip of the blade and the inner circumference of the cylinder is M and the inner diameter of the cylinder is D, the M/D ratio is 0.01 to 0.10, and the material supplied to each of the treatment zones is allowed to move to another treatment zone by 10% by volume or less,
In each of the treatment zones, the material to be treated is oxidized at 850 to 900° C. while being stirred, crushed, and sized ;
A rotary stirring type heat treatment device characterized by the above. The rotary stirring type heat treatment device according to claim 1 , characterized in that the number of blades of the ruddy blade is 8 to 16 , and the proportion of the cross-sectional area of the cylindrical portion in the radial cross section of the cylindrical body is 25 to 35%. 3. A method for heat treating an object to be treated, comprising using the rotary stirring type heat treatment device according to claim 1 or 2 .

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