JP2002213716A - Reduction melting method by oscillating kiln and kiln used in reduction melting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem on a method using a rotary kiln. SOLUTION: A reducing agent is added in dust sludge, containing a metallic component, and iron ore for heating to effect reduction by a kiln 31 situated in a down-grade toward the discharge side. Through removal and melting of zinc, slug is separated to recover a metal. In a reduction melting operation method, described above, charged dust sludge is conveyed to a discharge end through reciprocation rotation oscillation of the kiln 31. Reduction/zinc removal and melting operation are effected through a feed of heat from a burner flame 5a in a free board 3. Thus, in a way that recovery of a valuable metal, such as sludge, containing a metallic component, and processing for the use of slug as resource are carried out with stability, the increase of a processing amount, reduction of fuel unit requirement, and reduction of a processing cost are practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for recovering dust and sludge containing metal components generated from a metal smelter, valuable metals of fine iron ore unsuitable for sintering operations, and recycling slag. The present invention relates to a reducing and melting method using an oscillating kiln and a kiln used in the reducing and melting method.

[0002]

2. Description of the Related Art In a reduction dezincing and melting operation of dust and sludge by a rotary kiln, an object to be treated such as dust and sludge (hereinafter, simply referred to as "object to be treated") is continuously rotated in one direction in a cylindrical rotary kiln. In the process of transporting from the loading end to the discharge end,
Heat is applied to the processing object by a heating burner arranged so that the combustion gas flow is parallel to the moving direction of the processing object, and drying, heating, reduction, evaporation of low-boiling substances, heating, and high-boiling substances are performed. A method of melting and separating from slag components is disclosed in
No. 22217.

[0003] In this Japanese Patent Application Laid-Open No. 9-222217, the inside of the rotary kiln does not circulate the low boiling point metal in the exhaust gas, so that the adhesion is originally small, and the ratio of the length L to the inner diameter D of the rotary kiln L / D ( (See FIG. 6)
By setting the temperature below, the temperature of the entire rotary kiln is raised to a high temperature so that the deposits do not substantially adhere to the inner wall surface of the rotary kiln, and even if the deposits are formed, the flame of the heating burner provided on the upstream side is provided. It is said that the adhesion can be melted and removed by the adjustment.

[Influence of one-way continuous rotation]
Even in the method proposed in Japanese Patent Application Laid-Open No. 9-222217, there is a problem in the actual operation that deposits grow on the furnace wall of the rotary kiln and the processing capacity is greatly reduced. Then, the present inventors elucidated the mechanism of deposit growth as a result of various studies.

As shown in FIG. 6 (a), a cylindrical rotary kiln 1 which is inclined in such a manner as to have a downward slope in the longitudinal direction toward the discharge end, is connected to the rotary kiln 1 as shown in FIG. 6 (b). While rotating continuously in the direction (counterclockwise in FIG. 6B), the process up to the stage before melting, such as drying, raising the temperature, reducing, and evaporating the low-boiling substance ( (The location upstream of the rotary kiln), the furnace wall of the rotary kiln 1 has
In this case, the material escapes from the sedimentary layer (hereinafter, referred to as “bed”) 2 forming a slope at an angle to the space (hereinafter, referred to as “freeboard”) 3 through which the combustion gas 7 flows, and the freeboard 3. , And sneaks under the bed 2 again.

[0006] In the above-described process, the object to be treated is reduced by a reducing material such as coal in the bed 2, and the reduced material 4 attached to the furnace wall is removed when passing through the free board 3.
It is re-oxidized by abundant oxygen or carbon dioxide gas or causes a decarburization reaction.

In the case of re-oxidation, the state returns to a low melting point oxide such as FeO (melting point: 1356 K) lower than the melting point (1448 K, C = 4.25 mass%) of the iron-reduced metal component. As a result, it becomes easier to produce a compound with other slag components.

On the other hand, in the case of decarburization, the temperature of the free board 3 is higher than the temperature of the bed 2 by about 100 to 200 K, and the distance between the heating burner 5 and the burner flame 5a is the shortest at point c (FIG. b))).
The radiant intensity increases exponentially, and the reduced iron particles are heated and once melted to try to reduce the surface oxidized portion with internal carbon.

Accordingly, carbon is released from the reduced iron as CO gas, consumed by combustion, the carbon content is reduced, and the melting point of the molten iron is increased. afterwards,
As the distance from the burner flame 5a decreases, the temperature decreases, and solidifies to form deposits that are difficult to re-melt.

The reducing agent (coal, etc.) 4 adhering to the furnace wall directly burns, and ash such as SiO 2 remains on the furnace wall to make the surface of the adhering substance sticky. Is likely to adhere. By repeating this, a ring-shaped deposit 6 as shown in FIG. 7 is formed.

[Influence of Rotation (1)] When the powdered reductant 4 attached to the rotating furnace wall passes through the free board 3, it falls and scatters away from the wall surface by the burner flame 5a, the combustion gas 7, and gravity. Therefore, the transparency of the free board 3 decreases, and the free board 3 becomes cloudy as indicated by 8 in FIG. 6B.

When the deposit 6 grows on the furnace wall of the rotary kiln 1, the object to be treated is lifted in large quantities by the unevenness of the deposit 6, falls in the free board 3 above the bed 2, and becomes cloudy on the free board 3. 8 becomes stronger. Due to the cloudiness 8 of the free board 3, as shown in FIG. 6B, the heat radiation of the burner flame 5a (arrow 9 in FIG. 6B).
), The heat radiation 9 does not reach the surface of the bed 2 directly, the amount of heat transfer to the dust is reduced, the temperature of the object to be processed is insufficiently increased, the processing speed is reduced, or the rotary kiln 1 There has been a problem that the calorific value of the exhaust gas to be discharged is increased and the unit fuel consumption is deteriorated.

[Influence of rotation (2)] After completion of reduction,
Further, at the position immediately before melting (downstream from the middle part of the kiln) where the temperature is raised, as shown in FIG. Metal droplet 12 further assembled via droplet 11
Then, dropping starts in the bed 2 while leaving the slag 13 from the object to be processed originally existing, but this dropping does not occur unless the metal droplets 12 have a sufficient size.

However, since the rotary kiln 1 rotates continuously in one direction, the rising speed of the bed 2 (indicated by an arrow 15 in FIG. 9) is lower than the dropping speed of the fine metal droplet 11 (indicated by an arrow 14 in FIG. 9). Or the slag 13 disperses the heat of the minute metal droplets 11 that the circulating motion of the bed 2 (indicated by the arrow 16 in FIG. 9) is about to collect and solidifies again. For example, the entanglement of the metal droplets 11 prevents the collection of the metal droplets 12 and lowers the recovery rate of valuable metals.

Even if a small pool 17 is formed at a position where the molten metal accumulates (downstream of the kiln), some of the molten metal adheres to the furnace wall as shown by 18 in FIG. Some of the particles adhere to the processing object particles immersed in the pool 17 and escape from the pool 17, and these are deprived of heat in the bed 2 and solidified.

Further, the molten metal 18 adhering to the furnace wall undergoes reoxidation, remelting and decarburization when passing through the free board 3 containing a large amount of oxidizing gas, and melts again when it enters the pool 17 again. Since it is reduced by carbon in the metal, the carbon content in the molten metal decreases, and the melting point of the pool 17 increases.

In any case, the molten metal pool 17 works in a direction to reduce the amount of the pool, so that the molten metal pool 1
It was not easy to stabilize 7. Therefore,
It is not preferable that the furnace wall that has passed through the free board 3 is brought into contact with the pool 17, and it was necessary to supply sufficient carbon to prevent this.

[Radiation intensity position (1)] The rotary kiln 1 in which the object to be charged and the combustion gas 7 flow in parallel is used.
In FIG. 11, the position (point b) where the thermal radiation intensity 19 of the combustion flame 5a by the heating burner 5 provided on the charging-side end face 1a of the object to be treated is highest is as shown in FIG. 1-5m from the tip of the burner 5,
In the case of gaseous fuel, it is located closer to the heating burner 5.

Therefore, the free board 3 near the melting start portion downstream of the kiln where the bed 2 requires the highest temperature
In addition, it is difficult to arrange the position where the heat radiation intensity of the burner flame 5a is the highest, like the ideal heat radiation intensity distribution indicated by the broken line 20 in FIG.

Therefore, as shown by the solid line at 19 in FIG. 11, the treatment is rapidly performed by strong heat radiation upstream of the rotary kiln 1 until the reduction, but then the temperature of the object to be treated must be raised to the melting temperature. Since the heat radiation intensity from the burner flame 5a has already weakened at the required position, it was necessary to heat the rotary kiln 1 over a long range.

From the above, the actual temperature distribution 27 of the object to be processed is shifted to the upstream side of the rotary kiln 1 with respect to the ideal temperature distribution indicated by the broken line 21 in FIG. Due to the lowering, the region 22 (see FIG. 12) where the object to be processed just before melting actually rolls becomes longer than the ideal rolling region 23 (see FIG. 12). As shown in FIG. 13, due to the synergistic effect, the ring-shaped attached matter 6 is easily formed.
The formation range of the water pool 17 is limited to the downstream side of the ring-shaped deposit 6 (weir 6a (see FIG. 13A)).

Therefore, the heat radiation 9 is cut off by the ring-shaped deposit 6, and the heat supply is further reduced, so that the temperature of the object to be processed is hard to rise. As a result, the melting process is not stable, and the processing capacity is reduced. was there.

[Radiation intensity position (2)] An object to be processed within a range of 1 to 5 m from the charging side end face 1a of the rotary kiln 1 is being dried, heated, and reduced, and is not required to be melted. In spite of this, since the radiation intensity is high as described above, each dust particle located on the surface of the bed 2 has its surface temperature rise to the melting or softening temperature due to the strong radiation heat, and the surface temperature is temporarily changed. Only melts. Therefore, the surface of the particles is covered with the liquid slag, and the particles adjacent to the particles to be treated are combined and coarsened.

If the coarsened dust particles have a size of up to several millimeters, the scattering of the particles accompanying the generated reducing gas is reduced, but if the coarsened dust particle diameter becomes larger, the inside of the particles of the reducing gas is reduced. Intrusion into the
Further, there is a problem that the reduction rate is reduced because the reaction area is reduced.

When the reduction rate is reduced, the temperature of the dust particles increases and the slag begins to stick before the reduction of the metal is sufficiently completed. Stabilizes the molten metal pool 17 by inhibiting evaporation of the molten metal, forming large lumps by combining rolling with the contact particles, and flowing as a semi-molten lava. This causes problems such as a decrease in the metal recovery rate, insufficient evaporation and removal of low-boiling substances such as zinc, and destruction of the apparatus due to a drop impact when discharging large lumps.

[Radiation intensity position (3)] The object to be treated within the range of 1 to 5 m on the charging side end face 1a of the rotary kiln 1 is sometimes strongly intensely radiated and may be rapidly reduced and heated to melting. However, the carburization of the molten metal does not proceed sufficiently, and only the molten metal is melted at a high temperature. Therefore, when the molten metal flows down to a lower temperature portion on the downstream side of the rotary kiln 1, there is a problem that the molten metal is easily solidified and the melt disappears.

Compared to a fine metal that has never been melted,
The solidified metal once melted and assembled has a very small surface area per unit weight, so that the reaction area is small. Therefore, once the melted material with insufficient carburization solidifies once, even if there is sufficient carbon in the surroundings, the carburizing speed in the solid state is slow, so there is almost no effect of lowering the melting point of the metal, and it is almost remelted. I couldn't do that. Therefore, the recovery rate of valuable metals has decreased, and it has been difficult to stably maintain the hot water pool.

[Influence of fogging] In the rotary kiln 1 in which the object to be treated and the combustion gas 7 are made to flow in parallel, if a fogging phenomenon occurs due to dust scattering due to rotation of the rotary kiln 1,
On the upstream side of the rotary kiln 1, the combustion reaction of coal or the like previously mixed as a reducing material in dust and sludge is preferentially performed by the combustion oxygen supplied from the charging section of the rotary kiln 1, Insufficient oxygen for combustion of the heating burner 5 causes discharge of unburned burner fuel from the discharge side end face 1b of the rotary kiln 1 and insufficient carbon for carburizing of metal generated in a high-temperature portion downstream of the rotary kiln 1. . Therefore, deterioration of fuel consumption rate,
Insufficiency of carburization into the metal reduced the decrease in the melting point of the metal, increased the amount of unmelted metal remaining in the slag, and deteriorated the recovery rate of valuable metals.

[Removal of Deposits] As a method of removing deposits on the furnace wall of a rotary kiln, the applicant of the present invention has disclosed Japanese Patent Application 200
In No. 0-91928, charging of the object to be treated was stopped,
A method has been proposed in which only the reducing agent such as coal is charged and the inside of the furnace is reduced to a strong reducing atmosphere to reduce and remove the deposits again.
Unless the temperature is maintained for several hours to several days at a high temperature of 0 to 100 K, it cannot be removed, and there is a problem that the throughput of the object to be treated is reduced and the fuel consumption is deteriorated.

[Inlet Spill] The deposit 6 that grows on the inner wall of the rotary kiln 1 blocks the flow of the material to be treated at the weir 6a, so that the bed 2 upstream of the weir 6a
As shown in FIG. 14A, a fixed wall 25 supporting the heating burner 5 and the dust inlet 24 arranged on the charging side end face 1a of the rotary kiln 1 as shown in FIG.
The object to be processed inserted from the gap 26 with the rotary kiln 1 spills. If the amount becomes large, it becomes impossible to continue the operation. Therefore, after stopping the furnace and cooling, it is necessary to remove the weir 6a inside the rotary kiln 1.

Japanese Patent Application Laid-Open No. 2000-154910 proposes an oscillating incinerator. The oscillating incinerator is used for incineration. It is intended to improve the efficiency of waste combustion by supplying and not reducing and melting dust and sludge. In the case of the reduction furnace targeted by the present invention, it is necessary to keep the surface atmosphere of the material layer to be treated in a reducing atmosphere, so that the position of the heat supply flame needs to be kept away from the bed surface layer, and inevitably the free board Therefore, the ceiling cannot be suppressed to the vicinity of the center of swing as in the incinerator proposed in JP-A-2000-154910.

In addition, the incinerator proposed in Japanese Patent Application Laid-Open No. 2000-154910 is for drying, incinerating, and melting waste and the like. Heat is stored and reflected to improve the thermal efficiency, and is oscillated to be conveyed in the furnace,
It does not reduce and melt dust and sludge. The swing range is also 30 to 60 °, which is smaller than the swing range (approximately 210 ° or less) required for the reduction and melting of dust and sludge. There is a problem that stable transfer in the furnace cannot be performed.

[Refractory] The applicant of the present invention is a rotary kiln 1
Japanese Patent Application No. 11-318559 proposes an operation method in which a protective layer containing metallic iron is formed before processing an ordinary object to be processed in order to extend the life of the refractory on the inner wall of the device.
In the pool in which the molten metal always stays, the carbon in the molten metal is carburized into the metal in the protective layer to lower the melting point, so that the protective layer is quickly consumed.

Further, since the rotary kiln rotates in one direction, the material of the refractory in the pool is required to be changed or renewed over the entire circumference. When a system brick is used, there is a problem that an oxidation reaction occurs in the free board and the brick itself is oxidized and worn.

Further, since the rotation of the rotary kiln in one direction causes the position of the brick with heavy consumption to be inconstant in the circumferential direction of the rotary kiln, the place where the molten iron intrudes into the brick joint is not constant. Therefore, when renewing a brick, it is necessary to replace the entire circumference at a certain position in the length direction of the rotary kiln, and the basic unit of the brick has been increased. When hot metal enters the joints of the brick, if the amount is small, it accumulates between the steel shell and the brick and solidifies, but if it enters a large amount, the steel shell is melted and the hot metal spills out of the furnace. There is a problem in that there is a risk of a dangerous state such as burning of the product or a human disaster.

[0036]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned various problems, and a reduction melting method using an oscillating kiln and a kiln used in the reduction melting method capable of improving the following points. It is intended to provide.

1. Reduce the fogging phenomenon on the freeboard in the kiln, increase the rate of direct heat radiation from the burner flame to dust and sludge, and increase the thermal efficiency in the kiln furnace.

2. While forming a hot water pool over a wide area,
By mitigating the influence of the thermal radiation intensity distribution of the burner flame by the convection, and also preventing the formation of ring-like deposits in the middle part of the kiln, the heat supply of the object to be processed is mainly performed from molten metal, Temperature rise, reduction, dezincification, temperature rise,
Carburize, melt, and separate slag to achieve stable operation continuously.

3. By extending the bricks so that the material is suitable in the circumferential direction according to the swing range, the life of the bricks is increased and the cost of the refractory is improved.

[0040]

In order to achieve the above-mentioned object, a reduction melting method using an oscillating kiln according to the present invention comprises adding a reducing material to dust or sludge containing a metal component and iron ore, heating the same. In the kiln arranged so as to have a downward slope toward the discharge side, zinc is removed and melted to separate slag and collect metal.
Sludge is conveyed to the discharge end by the reciprocating rotation of the kiln, and reduction, dezincing and melting operations are performed by heat supply from a burner flame in the freeboard. By doing so, the fogging phenomenon on the free board in the kiln is reduced, and the thermal efficiency in the kiln furnace is increased. In addition, a pool of water is formed over a wide area, and the heat radiation intensity distribution of the burner flame is generated by the convection. In addition, by mitigating the effects of the above, preventing the formation of ring-like deposits in the middle part of the kiln, and by supplying heat mainly to the molten metal from the molten metal, the temperature can be quickly raised, reduced, dezincified, Continuous operation can be achieved by raising the temperature, carburizing, melting, and separating slag.

When the brick material in the range of the pool of the main contact material and the range of the freeboard of the kiln used in the reducing and melting method using the oscillating kiln according to the present invention are divided in the circumferential direction of the kiln. In this case, the life of the brick can be extended, and the cost of the refractory can be improved.

[0042]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The reduction melting method using an oscillating kiln according to the present invention, which can solve the above-mentioned various problems, and the concept of a kiln used in the reduction melting method will be described step by step.

[Principle of Oscillating Conveyance] When the object to be processed is solid and granular, assuming that the angle of repose of the object to be processed is θ °, FIG.
As shown in (2), the rotation of the kiln 31 forms a slope of θ ° to form the bed 2 constantly. In fact, Figure 1
As shown in (b), after the object to be processed is lifted along the rising line 32 in a direction perpendicular to the center line 31a of the kiln 31 to an inclination angle of θ ° + α ° (see FIG. 2), the object to be processed is mainly processed. The part from the angle of repose θ ° to α ° of the object (B in FIG. 1B)
1, the area surrounded by B2 and B3) collapses, and at this time, it rolls along the rolling line 33 while being shifted from the center line 31a of the kiln 31 by the inclination angle β ° in the workpiece transfer direction ( (See FIG. 2). Therefore, the workpiece can be transported in the discharge direction by repeating such rotation swing while changing the direction.

The first method of reducing and melting by the oscillating kiln according to the present invention uses the above-described oscillating transport principle.
By reciprocatingly oscillating a kiln arranged so as to have a downward slope with an inclination angle β ° toward the discharge side,
The bed is moved to the left and right of the cross section of the kiln to cause the above-mentioned collapse and rolling on the left and right sides of the kiln, and is gradually conveyed in the discharge direction so that the molten metal is reduced and melted while being constantly conveyed. By forming to the side,
This is to narrow the swing range.

[Explanation of swing range (1)] In the above-described reduction and melting method using the swing kiln according to the first aspect of the present invention, while the object to be processed is in the form of solid particles, the rolling conveyance is performed.
The swing range necessary for this will be described with reference to FIG. 1 focusing on the point a at the right end of the bed 2 and the refractory surface position A in contact therewith.

The case where the occupied angle γ ° of the bed 2 in the cross section of the kiln 31 is 90 ° and the angle of repose θ ° is 45 ° will be described. The kiln 31 is shifted from the state shown by the solid line in FIG. When rotated, the bed ends A and a are pointed out as shown in FIG.
It moves to the points A1 and a1 indicated by the imaginary line in FIG.

As shown in FIG. 1 (b), when the bed 2 is further rotated by α °, the end of the bed 2 moves to the points A2 and a2, and the area surrounded by the points a2, B2 and B3. Bed 2 of the bed collapses and moves to a position surrounded by B2, B4, and B5. After the collapse, the end of the bed 2 settles at the point a3.

When it is further rotated by 45 °, as shown in FIG. 1C, the initial point of the refractory in the kiln 31 moves to A4, and the end of the bed 2 comes to the position of a4 and collapses. Except for the area surrounded by a4, B7, and B8, all of which have collapsed and rolled.

When the kiln 31 is rotated in the opposite direction to move the refractory point A4 to A5 in FIG. 1 (d) in order to roll the area surrounded by a4, B7 and B8 which has not collapsed. The end a4 of the bed 2 moves to a5. When the kiln 31 is further rotated to move the refractory point A5 to A6, the point a5 of the bed 2 moves to the virtual point a6,
In FIG. 1C, the area surrounded by a4, B7, and B8 has all rolled. Therefore, by rotating and reciprocating the kiln 31 as described above, the workpiece can be rolled and discharged without remaining.

[Explanation of swing range (2)] In the reduction melting method using the swing kiln according to the first invention, the kiln 3
The swing range ε when there is no molten material in 1 (see FIG. 1D) is 4 × θ ° (provided that the layer thickness of the bed 2 is h and the inner radius of the kiln 31 is r, h <r × (1-cos2
θ)), the contact range η (see FIG. 1 (e)) of the object to be treated on the furnace wall of the kiln 31 is (ε + 3/2 × γ).
°.

For example, the occupation angle γ of the cross section of the kiln of the bed 2
When the angle is 100 ° and the angle of repose θ is 42 °, the swing range ε is 168 °, and the contact range η of the workpiece to the furnace wall is 303 °. Angle of repose of dust and sludge is 40 ~
Since the angle is 50 °, the swing range ε is in the range of 160 to 200 °, and the dust and sludge can be sufficiently conveyed in the kiln.

Regarding the layer thickness h of the bed 2, the kiln 31
It depends on the diameter, number of revolutions, inclination angle, angle of repose and the amount of treatment, and varies depending on the case. However, in the case of dust reduction, the bed thickness h of the bed 2 is generally from several% of the diameter to about 2%.
0%, and the angle of occupation of the kiln cross section of the bed 2 is generally not more than 100 °.
Is a range δ that is not more than 320 ° and does not come into contact with the object at all.
Is (360−η) °.

[Effect of Oscillation] That is, in the reduction melting method using the oscillating kiln according to the first aspect of the present invention, since the contact area η of the workpiece to the furnace wall does not extend over the entire circumference of the kiln 31. The deposits 34 formed on the furnace wall do not have a ring shape as shown in FIG. Therefore, the amount of deposits falling from the upper furnace wall of the freeboard 3 is reduced, and the phenomenon of fogging the freeboard 3 is reduced, so that the radiation heat transfer efficiency can be improved.

The center position of the swing range on the wall surface of the kiln 31 is shown in FIG.
The position is changed from the position indicated by A7 in FIG. 3A to the position indicated by A8 in FIG. 3B, and the attached matter 34 is melted and dropped by the strong width radiant heat of the burner flame 5a. Operation can be continued without the need to reduce

When the partial deposit 34 grows in this way, if the position of the deposit 34 is positioned above the free board 3 and the hot burner 5 is exposed to the heat radiation over a short distance, the slag can be obtained. It can be melted and removed by falling under its own weight. This is the second reduction melting method using the swing kiln according to the present invention.

By the way, the shape of the adhered substance 34 during the swing reduction is not uniform, and is near the center of the swing range A9 (FIG. 3A).
2), the contact time with the bed 2 is prolonged, the temperature change is small, and the bed 2 is exposed to a strong reducing atmosphere due to the generated CO gas. On the other hand, A8 near both ends of the swing range is exposed to the free board 3 for a long time, so that the temperature of the wall surface is high and the reducing atmosphere is weak, so that the deposits 34 are easily formed.

Therefore, in the case of the present invention, the adhered substance 34 formed does not have a competing shape, so that the vertical force due to its own weight acts and peeling or falling off becomes easy. Even if the contact area of the object to be processed extends over the entire circumference of the kiln 31 under the conditions such as the physical properties of the object to be processed, the layer thickness, etc., since the form of the attached matter 34 is not a uniform ring shape, the competing force is weak. Can be removed by the following method.

As described above, according to the present invention, while the free board 3 is oxidized and melted to drop the deposits 34, the bed 2 can continuously perform the reduction treatment. Therefore, it is possible to stabilize the operation without reducing the amount of material to be treated, spilling from the charging side, or removing operation by charging only coal.

In the present invention described above, the specific gravity of the pool 17 at the bottom of the kiln 31 which is blocked and accumulated by the weir 31b formed on the discharge side end face 31c of the kiln 31 has a specific gravity because the formed product is a molten metal. As shown in FIG. 3D, the object to be processed is suspended in the pool 17 as shown in FIG.

Therefore, the movement due to the floating flow on the pool 17 can reduce the swing range ε, and the contact range η between the wall surface and the solid conveyed material is greatly reduced. It is possible to further reduce the amount of an object to be processed such as dust that falls off from the furnace wall. This is the third reduction and melting method using the swing kiln according to the present invention. According to the third aspect of the present invention, the reduction and melting method using the oscillating kiln further reduces the fogging of the freeboard 3, improves the efficiency of heat transfer to the object to be treated, improves the fuel consumption rate, and improves the processing capacity. The improvement can be achieved.

[Change of swing range due to pool forming range] When the molten metal pool 17 does not reach the upstream side of the kiln 31, the swing range ε is set to such an extent that the pool 17 does not disappear. By increasing the size, giving priority to the transport of the workpiece on the upstream side, and reducing the swing range ε after the pool 17 reaches the upstream side, the workpiece can be transported efficiently. .

[Limiting of Pool Formation and Effect of Pool] The formation of the pool 17 is, as shown in FIG.
Although it spreads from the discharge side end face 31c of the kiln 31 toward the charging side end face 31d, at least to the upstream side from the strongest position (point b) of the heat radiation 9 from the burner flame 5a of the heating burner 5, the charging It accumulates to the side end face 31d.

Thus, the range γ1 where the molten metal is in contact (see FIG. 3 (a)) is to reduce the metal oxide in the deposit 34 by the carbon in the molten metal to remove the deposit 34. As a result, the deposits 34 do not grow in a ring shape. Therefore, it is possible to reliably transfer the object to be processed in the furnace.

The range not in contact with the molten metal (η-γ1
In the case of the present invention, even if the deposit 34 on the furnace wall grows to some extent, the force competing in a ring shape does not work in the case of the present invention.
4 falls off by its own weight and falls.

Further, the bed 2 of the object to be treated is
Is immersed, the metal droplet 1 in the solid workpiece is
2 can easily assemble into the sump 17 without dripping in the bed 2, and the carbon in the object to be treated is easy because solid carbon is immersed in the molten metal of the sump 17. The carbon content consumed by the reduction by the hot water pool 17 can be replenished.

Solid fine metal droplets 1 in solid object 2
Also, since 0 is oscillated while being immersed in the basin 17 and is washed with the molten metal, heat and carbon are quickly supplied from the molten metal to be melted and easily collected in the basin 17.
Therefore, the recovery rate of valuable metals can be improved.

[After the formation of the pool, from the swing to the one-way rotation] When the pool 17 is not formed, or when the pool 17 is not formed.
Grows to the highest position of the heat radiation 9 of the burner flame 5a, when it has not reached, the kiln 31 is reciprocally rotated and oscillated to reduce and melt, and the pool 17 is formed without forming the deposits 34 in a ring shape. The water pool 17 is formed and gradually grown. After the pool 17 reaches the upstream side of the kiln 31, the kiln 31 may be rotated in one direction. This is the fourth reduction and melting method using the oscillating kiln according to the present invention. In the reduction melting method using the rocking kiln according to the fourth aspect of the present invention, carbon sufficient to reduce the reductant 4 in the freeboard 3 with the carbon in the pool 17 is previously added to the object to be charged. Should be blended.

[Heat Transfer] In the supply of heat,
7 is immersed in the workpiece (bed 2) having a relatively low temperature, so that heat is transferred between the solid-phase workpiece (bed 2) and the liquid-phase molten metal (pool 17). As a result, heat is quickly supplied from the molten metal, and the temperature of the object to be treated (bed 2) increases, and the reduction reaction can proceed significantly.

Moreover, the carbon in the object (bed 2) is directly supplied to the molten metal (pool 17) and the carbon in the molten metal (pool 17) is contained in the object (bed 2). Since the solid micrometal 10 is transferred to the solid micrometal 10, the melting point of the solid micrometal 10 is lowered, and the solid micrometal 10 is moved to the pool 17 and aggregated, so that the throughput and the recovery rate of valuable metals can be improved by improving the reduction rate.

On the other hand, since a reduction reaction, which is an endothermic reaction, occurs in the molten metal, the temperature of the molten metal tends to decrease. However, since the pool 17 is located immediately below the strongest point of the burner flame 5a, The molten metal convects due to the temperature difference between the low-temperature pool portion and the high-temperature pool portion, and the convection can supply heat to the low-temperature pool portion.

When the range of existence of the pool 17 is increased and the swing range ε of the kiln 31 is reduced, the rate of heat supply is reduced due to the furnace wall having a high temperature sinking into the pool 17. However, this can be compensated for by the fact that the transparency of the free board 3 is increased, and the heat radiation 9 of the burner flame 5a and the heat radiation from the furnace wall are directly received.

Further, the pool 1 on the downstream side of the kiln 31
In the seventh part, the heat radiation 9 from the burner flame 5a is small and the ratio of the contact heat transfer from the furnace wall is large, so that the heat supply is insufficient.
Since high-temperature molten metal flows in continuously from 7 and heat is supplied, the pool 17 has a substantially uniform temperature without a local temperature difference.

[Swinging Effect (1)] The present invention relates to a kiln 31.
In order to oscillate, the furnace wall that has passed through a place where the oxygen concentration is extremely high, such as directly above the heating burner 5 of the freeboard 3, does not come into contact with the pool 17 and only contacts the furnace wall with a low degree of oxidation. As a result, decarburization of the water pool 17 is reduced.

Further, according to the present invention, the surface of the basin 17 is substantially covered with the object to be treated, and the molten metal 18 adhered to the furnace wall coming out of the basin 17 portion. Does not rotate to the upper part of the free board 3 having a high concentration of oxygen or carbon dioxide, so that the degree of oxidation is low, and the pool is again immersed in the pool 17 so that the pool becomes stable.

[Effect of Oscillation (2)] Regarding the prevention of the formation of deposits inside the kiln 31, according to the present invention, the contact range η of the object to be treated with the furnace wall is approximately 210 ° or less, and the ring-like shape is completely ring-shaped. Since it does not become an attached matter, it does not become difficult to peel off due to the competition of the attached matter 34 itself. Also, by always keeping the molten material upstream of the kiln 31,
The water pool 17 and the furnace wall or the deposit 34 attached to the furnace wall
To reduce oxides that function as binders when deposits are formed, thereby preventing the formation of deposits 34 and gradually removing the deposits 34 once formed.

Therefore, according to the present invention, the thick deposit 3
Since the formation of the material 4 does not hinder the conveyance of the object, the contents of the furnace are less likely to spill out from the gap on the charging side of the kiln 31, and stable operation can be performed for a long time.

[Refractory] In the reduction melting method using the oscillating kiln according to the present invention described above, the refractory lining the kiln 31 comes into contact with the pool 17 because the kiln 31 performs the oscillating motion. The range in the circumferential direction will be limited.

Therefore, as shown in FIG.
By changing the material of the refractory lining the area ε1 in contact with the pool 17 on the inner circumference, the area η1 in contact with the solid object, and the area δ1 not in contact with the object, a long life can be obtained. And brick cost can be reduced. This is the kiln according to the fifth aspect of the present invention.

For example, only the rocking range ε1 to be performed when the pool 17 has sufficiently developed and reaches the upstream side is to use a brick having a high SiC component among the SiC-based bricks which is strong against the molten metal.
The range of contact η1 of the workpiece due to other swings is S
Among the iC-based bricks, bricks having a low SiC component are used, and the range δ1 not in contact with the object to be treated is to use alumina-based bricks having high heat insulation performance.

By changing the material of the refractory lining as described above, the portion of the kiln 31 that is worn in the circumferential direction is limited, and only the worn portion needs to be replaced. Therefore, during operation, safety can be ensured only by focusing on the insertion of hot metal in a specified range on the circumference into the joint, and the like.

[0081]

EXAMPLES The results of experiments conducted to confirm the effects of the present invention will be described below. In recovering valuable metals, the recovery rate of valuable metals that could be recovered as a product was 25 to 48% of the theoretical recovery amount by a conventional method using a rotary kiln, but the present inventor has found that the recovery rate is As a result of checking the properties of valuable metals contained in slag,
It turned out that a large amount of fine-grained iron was contained, and it could be predicted that the recovery rate could be easily increased by immersion in molten metal.

Therefore, the present inventors used a mixture of dust and sludge generated from the interior of a steel mill and coal as a reducing agent, charged the mixture into a kiln with a diameter of 4.2 m and a length of 14 m, When reduced and melted by the method of the present invention, it was possible to recover up to 83 to 90% of the theoretical recovery amount.

At this time, by adopting the method of the present invention, the amount of deposits formed on the inner peripheral surface of the kiln can be suppressed as compared with the conventional method, and the deposits are not ring-shaped. The competing force was weak, and it was possible to easily remove the melt by changing the swing range so that the attached matter was located at the highest temperature of the freeboard.

[0084]

As described above, according to the present invention,
It has the effects listed below. 1. In the process of recovering valuable metal from dust and sludge containing metal components generated from metal smelters such as steel mills and recycling slag, it is possible to stably recover molten metal, thereby increasing the amount of processing. It is possible to reduce the unit fuel consumption and the processing cost.

2. In addition, since the amount of valuable metals that can be recovered is increased and harmful components in the metals are also removed, the adjustment of raw material components becomes unnecessary, and the added value of the recovered metals is improved.
It becomes easy to reuse as resources.

3. Refractories can also be placed at a high priority, costs can be reduced, and factors that lead to serious accidents and disasters, such as intrusion of hot metal into joints, can be easily monitored and managed.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views illustrating the principle of swinging conveyance of an object to be processed in a kiln, as viewed from a cross section.

FIG. 2 is a diagram illustrating a principle of swinging conveyance of an object to be processed in a kiln, as viewed from a longitudinal direction.

FIGS. 3 (a) to 3 (d) are illustrations of deposits formed in a kiln and removal of the deposits.

FIG. 4 is a view for explaining a formation range of a hot water pool;

FIG. 5 is an explanatory diagram of a case where a brick region of a pool and a brick material of a freeboard are divided in a circumferential direction of a kiln;

FIGS. 6A and 6B are explanatory diagrams of a reduction melting method using a rotary kiln, wherein FIG. 6A is a diagram viewed from a longitudinal direction, and FIG.

FIGS. 7A and 7B are explanatory views of a state of deposit formation during reduction melting using a rotary kiln, where FIG. 7A is a view as viewed from a longitudinal direction, and FIG. 7B is a view as viewed from a cross-sectional direction.

FIG. 8 is an explanatory diagram from the melting to the dropping of dust or sludge containing metal components and iron ore from a kiln intermediate portion to a downstream side.

FIG. 9 is a diagram for explaining the behavior of a fine metal droplet in a rotary kiln.

FIG. 10 is an explanatory diagram of a hot-water pool forming portion on the downstream side of the rotary kiln.

FIG. 11 is an explanatory diagram of the thermal radiation intensity of a combustion flame in a rotary kiln in which an object to be treated and a combustion gas are fed in parallel.

FIG. 12 is an explanatory diagram of a temperature distribution of a processing object in a rotary kiln in which a processing object and a combustion gas to be charged flow in parallel.

FIG. 13 is a view for explaining that a deposit area formed in a rotary kiln limits a water pool formation range.

14A and 14B are diagrams illustrating that the thickness of the bed layer on the upstream side is increased by the deposits (weirs) formed in the rotary kiln, and the workpiece is spilled from the loading side. FIG. (B) is a view seen from the cross-sectional direction.

[Explanation of symbols]

 3 Free board 5a Burner flame 17 Hot water pool 31 Kiln 31b Weir 31e Refractory

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F27B 7/28 F27B 7/28 7/34 7/34 F term (reference) 3K061 AA09 AB03 AC02 BA04 CA01 DB14 KA02 KA08 KA09 KA15 KA27 4K001 AA10 BA02 BA14 DA01 DA06 DA10 GA07 GB05 HA00 4K061 AA08 BA04 BA12 CA17 CA23 CA29 DA03 FA01

Claims (5)

[Claims] 1. A reducing agent is added to dust or sludge containing metal components and iron ore, heated and reduced by a kiln arranged so as to have a downward slope toward a discharge side, and zinc is removed or melted. In the reduction and melting operation method of separating slag and collecting metal, the charged dust and sludge are conveyed to the discharge end by the reciprocating rotation of the kiln and reduced and supplied by the heat supply from the burner flame in the freeboard.
A reduction melting method using an oscillating kiln, comprising performing dezincing and melting operations. 2. When the deposits are formed on the conveying surface of the kiln, the swing range is changed so that the formed deposits are located at the highest temperature of the freeboard. 2. The reduction and melting method using an oscillating kiln according to claim 1, wherein the deposit is oxidized, melted, and dropped on the upper portion while performing the oscillating reduction. 3. A weir formed at the discharge end of the kiln,
When the melt is retained from the discharge end to the upstream side from the position of the highest heat radiation intensity of the burner flame,
The solid object to be treated is immersed in the retained melt by the reciprocating rotation of the kiln, and steps such as heating, reduction, carburizing, and melting of the object are performed.
Or a reduction and melting method using an oscillating kiln according to 2. 4. A reducing agent is added to dust sludge and iron ore containing a metal component, heated and reduced by a kiln arranged so as to have a downward gradient toward a discharge side, and zinc is removed or melted. In the reduction melting operation method of separating slag and collecting metal, in a stage in which the molten material is retained from the discharge end toward the upstream side by the weir formed at the discharge end of the kiln, when the retention range of the molten material is small. Is a reduction melting method using a rocking kiln according to any one of claims 1 to 3,
After the solid object to be processed is conveyed while being reduced by the reciprocating rotation of the kiln and immersed in the pool at the downstream side of the kiln, after the pool is formed from the discharge end to the charging end or a position in the vicinity thereof, A method of reducing and melting a rocking kiln, wherein the kiln is rotated in one direction to perform processes such as heating, reducing, carburizing, and melting the object to be processed. 5. The reduction by a rocking kiln according to claim 1, wherein the brick material in the range of the pool of the main contact material and the range of the freeboard are divided in the circumferential direction of the kiln. Kiln used for melting method.