JPH033733B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a method for recovering valuable metals contained in ordinary steel and special steel dust and sludge (hereinafter referred to as dust and sludge) generated in the process of manufacturing ordinary steel and special steel. This relates to a reduction roasting device used for roasting. [Prior art] Generally, dust and sludge generated when manufacturing ordinary steel or special steel contain Zn, Pb, and Cd.
While it contains harmful components such as Ni, Cr, and Fe, it also contains valuable metals such as Ni, Cr, Fe, etc., and it is difficult to treat it as industrial waste. Therefore, various treatment methods and equipment are being studied. As one means for this, some proposals have been made to charge the dust and sludge into a metallurgical furnace and reuse it. However, since the dust and sludge mentioned above contain harmful components such as Zn, Pb, and Cd, processing of the harmful components has the disadvantage of high costs, and furthermore, the recovery rate of valuable metals is low. It had the disadvantage of being low. Therefore, these dusts and sludges are reduced and melted in a special electric arc furnace, and Fe-
Equipment for manufacturing Ni-Cr alloys is also used in some areas. [Problems with the prior art] However, the above-mentioned dust and sludge are reduced and melted in a special electric arc furnace, and Fe-Ni
The method for producing -Cr alloys requires special equipment and uses expensive electrical energy, so there is a problem in that the cost is high. The present invention has been made in view of the above circumstances, and
A relatively simple device with low operating costs, it removes harmful components from dust and sludge, and also removes Ni,
The purpose of the present invention is to provide a reduction roasting device for dust and sludge that efficiently converts valuable metals containing Fe and Cr into reduced metals. [Means for Solving the Problems] The reduction roasting apparatus for ordinary steel and special steel dust and sludge according to the present invention in accordance with the above-mentioned object has a bottom part that is a grate that can be opened and closed, and an upper part that has an exhaust port and a raw material supply. A plurality of roasting zones are formed by disposing a grate that can be opened and closed in the middle part of the roasting furnace where the opening is provided, and each of the grate is opened and closed sequentially from the lower stage, and the raw material is fed through the raw material supply port. The agglomerated dust and sludge are sequentially transferred to the lower stage, and the roasted dust and sludge are discharged from a grate that can be opened and closed at the bottom. Here, the middle grate is the one in the center of the roasting furnace.
In addition to the case where only one piece is arranged, two or more pieces are arranged at a predetermined interval in the vertical direction.
This includes those in which a roasting zone is formed in stages or three or more stages, but in order to increase the roasting speed, it is preferable that the interval between the respective grate in the vertical direction is 1000 mm or less. In addition, the above-mentioned grate has a structure that opens and closes because it is necessary to drop the dust and sludge agglomerates on the upper part to the roasting zone on the lower stage when necessary. Those with a mechanism in which the grate slides horizontally to open and close, those with a mechanism consisting of an opening/closing plate in which the grate in the middle part is arranged horizontally at a predetermined interval, and one end is provided with a rotating shaft, or the middle part This also includes a mechanism in which the grate is made of a plurality of coarse grate members, and the opening of the grate becomes larger as the grate slides laterally to open and close the grate. [Function] Next, the method of using the roasting apparatus for ordinary steel and special steel dust and sludge according to the present invention and its function will be explained in more detail. First, with the bottom and intermediate fire grates closed, dust and sludge (hereinafter referred to as After a certain amount of agglomerated material is added, the grate is opened and closed from the lower stage to transfer the agglomerated material to the lower roasting zone. By operating in this way, there will be no agglomerates in the upper roasting zone, so the agglomerates will be supplied again from the raw material supply port and the agglomerates will be constantly charged into the roasting furnace. At the same time, ignite the agglomerated material with a burner, etc. from the lowest fire grate, connect a dust collector, etc. to the exhaust port, adjust the air volume of the dust collector, and at least burn the lowest stage. The burnt belt should be able to maintain a reducing atmosphere. After this, the roasting progresses to the top, and the entire bottom roasting zone becomes a high-temperature fire layer, and the time when the fire layer rises to the middle of the upper roasting zone through the grate installed above. Then, the grate at the bottom of the roasting furnace was opened to allow the roasted agglomerates to fall, and the agglomerates were placed in a prepared container. After closing the bottom grate, the intermediate grate immediately above is opened and the agglomerated material in the upper roasting zone is transferred to the lowermost roasting zone. In this case, since the agglomerated material has already been ignited by the above operation, there is no need to ignite it anew. Thereafter, the same operation as above is performed to transfer the agglomerated material in the upper stage to the lower stage. By this operation, the entire agglomerate in the lowermost stage is brought into a high temperature state of a reducing atmosphere, so that valuable metals are reduced and harmful components are volatilized. [Example] Next, a reduction roasting apparatus for ordinary steel and special steel dust and sludge according to an example of the present invention will be described with reference to the attached drawings to provide an understanding of the present invention. Here, FIG. 1 is a longitudinal sectional view of a reduction roasting apparatus for ordinary steel and special steel dust and sludge according to one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of ordinary steel and special steel dust according to another embodiment. , a partial schematic sectional view of a grate used in a reduction roasting apparatus for sludge. As shown in FIG. 1, a reduction roasting apparatus (hereinafter referred to as a reduction roasting apparatus) 10 for ordinary steel and special steel dust and sludge according to an embodiment of the present invention consists of a roasting furnace 11 and its auxiliary equipment. The roasting furnace 11 is provided with a fire grate 12 that can be opened and closed in the middle, and forms two upper and lower roasting zones 13 and 14. A truncated conical hood 15 forming an exhaust hole is connected to the upper part of the roasting furnace 11.
A duct 17 is connected to which an air volume control valve 16 is disposed midway and is connected to a dust collector (not shown). Further, the hood 17 is provided with a raw material supply port 18 for supplying predetermined raw materials to the roasting apparatus 10, and the raw material supply port 18 can be opened and closed at all times except when raw materials are supplied. A lid 19 is provided. Next, the grate 12 provided in the middle part of the roasting furnace 11 will be explained in detail.
2 consists of a lattice body that allows flames, air, etc. to freely pass through without allowing the agglomerated material placed on the top to fall through the lattice gaps, and the left and right lattice bodies 20, 21 are horizontally moved manually or by a driving means. It is designed to be opened and closed by sliding. On the other hand, the grate 22 provided at the bottom of the roasting furnace 11 consists of two left and right grate 22a, 22b, and rotating shafts 23a, 23b are arranged at one end of each grate 22a, 22b. and the rotation axis 23
The respective fire grates 22a, 22b center around a, 23b.
The structure is such that the grate 22 is opened and closed by rotating. In addition, it is also possible to use the above-mentioned grate 12 instead of the above-mentioned grate 22, and by doing so, it becomes possible to reduce the height of the entire reduction roasting apparatus. A hopper 24 equipped with a switching damper is provided at the bottom of the roasting furnace 11, and the material discharged from the roasting device 10 can be put into either one of the two containers 25 and 26 provided at the bottom. It's becoming like that. The containers 25 and 26 have lids 27 and 28, respectively, so that the objects stored in the containers 25 and 26 can be sealed tightly. Note that the roasting furnace 11 has partition plates 29 and 3.
0 is provided to ensure uniform air permeability and prevent uneven roasting inside. It is also possible to provide ventilation holes on the side of the roasting furnace, and by providing these ventilation holes appropriately, the necessary air can be replenished and the roasting of the agglomerates can proceed smoothly. There are cases where it is possible. Next, the operation of the apparatus for reducing and roasting dust and sludge according to the above embodiment will be explained in detail. First, as a preliminary work, the dust and sludge are kneaded with a reducing agent containing carbonaceous solid fuel necessary for reducing and roasting them, and a binder if necessary.Then, the dust and sludge are kneaded into a predetermined size using a sludge machine, etc. I'll make it happen. After that, the agglomerated material 31 of dust and sludge agglomerated by the above operation is collected in the hopper 32, and then delivered to a predetermined amount into the reduction roasting apparatus 10 from the raw material supply port 18 via the feeder 33. After charging, open the intermediate grate 12 and pour the agglomerated material 3.
1 is transferred to the lower roasting zone 14, and a predetermined amount of the agglomerated material is introduced from the raw material supply port 18 again to supply the agglomerated material 31 to the upper roasting zone 13 as well. In this state, the lower roasting zone 14 is ignited, the dust collector (not shown) is operated, and the air volume control valve 16 is turned on so that the inside of the roasting furnace 11 can maintain a reducing atmosphere. adjust. After that, the roasting progresses to the upper part and the lower roasting zone 14
When the entire area becomes a high-temperature fire layer and the fire layer rises to the middle of the upper roasting zone 6 through the intermediate fire grate 12, the fire grate 22 at the bottom of the furnace is opened to remove the roasted dust and sludge. The dust and sludge are dropped into the lower hopper 24 and put into the container 26 by operating the lower switching damper, and then the upper lid 28 is closed to cool the charged dust and sludge. in this way,
The roasted ore, which is roasted dust and sludge, is gathered up and put into the container 26 or 25 at once, so it is less susceptible to re-oxidation and can be easily charged to the metallurgical furnace in the next process. This means that it can be done. Next, after closing the bottom grate 22, the middle grate 12 is opened to transfer the agglomerates in the upper roasting zone 13 to the lower roasting zone 14, and then the grate 12 is closed and a new one is transferred. The agglomerated material 31 is transferred to the upper roasting zone 1.
Pour into Step 3 and continue roasting. By repeating the above operations, the agglomerated dust and sludge can be continuously roasted in the roasting furnace 11. Here, if the thickness of the roasting layer is too thick, the roasting speed will be slow and there is a risk of clinker formation, which will hinder continuous operation, so the thickness of the roasting layer of one stage should be 1000 mm or less to accelerate the roasting speed. In addition to the above-mentioned ventilation holes, it is preferable to appropriately allow air to enter the upper roasting zone 13 through the grate 12 provided at the bottom of the upper roasting zone 13. In addition, the partition plates 29 and 30 are used to make the agglomerated layer uniform in air permeability and to ensure uniform roasting in the roasting furnace 11, but the diameter of the roasting furnace is 500 mm or less. This is not particularly necessary for small-sized reactors. Through the above process, the agglomerated materials of dust and sludge are reduced and roasted, and as a result of the reduction and roasting, the agglomerated products of dust and sludge are reduced and roasted.
Harmful components such as Zn, Pb, and Cd can be reduced and volatilized, and valuable metals such as Ni, Cr, and Fe can be reduced and converted into metals. In this way, it was reduced and roasted to become a metal.
By putting valuable metals such as Ni, Cr, and Fe into a metallurgical furnace,
Collect valuable metals such as Ni, Cr, and Fe. Then, Zn, Pb, which was volatilized by the above process,
Volatile substances such as Cd are sucked into the dust collector and collected by the duct 17 provided at the top. In the above embodiment, a single grate 12 is provided in the middle of the roasting furnace 11 to divide the roasting zone into two vertically. It is also possible to form the roasting zone into three stages by installing a grate, which allows the uppermost roasting zone to receive heat from the airflow from below and heat up, improving thermal efficiency. will improve. Further, in the above embodiment, the grate is opened and closed by sliding the grate laterally in the middle part, but for example, as shown in FIG. 2, the grate 34
consists of opening/closing plates 36 arranged at predetermined intervals in the horizontal direction and having a rotating shaft 35 at one end, and when closing the grate 34, the opening/closing plates 36 are arranged horizontally in a row ( As shown in FIG. 2), it is also possible to open the grate 34 by rotating the pivot shaft 35 90 degrees clockwise. In this case, by appropriately providing ventilation holes 37 in the opening/closing plate 36, it is possible to increase the width of the opening/closing plate 36 to some extent. Furthermore, the above-mentioned grate is composed of two abutting members provided with large-diameter drop holes and small-diameter ventilation holes at predetermined intervals, and the upper and lower two members are allowed to fall by sliding horizontally. It is also possible to have a structure in which the holes are aligned, the grate is opened, the upper and lower drop holes are removed, and the grate is closed. In this case, if a mountain part with a slope larger than the angle of repose of the agglomerated material is formed in a place where a falling hole is not provided in the upper member, the agglomerated material placed on the upper member will be able to flow smoothly. It becomes possible to fall to the roasting zone at the bottom. [Experimental Example] Next, an experiment conducted to confirm the performance and effects of the reduction roasting apparatus for ordinary steel and special steel dust and sludge according to the present invention will be described. The reduction roasting apparatus used had the same structure as the reduction roasting apparatus according to the above example, and its dimensions etc. are as shown below. The upper part of the furnace is connected to the dust collector, and the cross section of the furnace body is
A rectangular shaft furnace measuring 1,300 mm x 1,300 mm and a height of 1,400 mm is equipped with a grate at the bottom and middle of the furnace, with a spacing of 700 mm between the two grate. 100 parts by weight of stainless steel electric furnace dust, which is an example of the same type, is mixed with 15 parts by weight of coke powder and parts by weight of Na ₂ CO ₃ .
After filling the briquettes with agglomerated 50mm x 40mm x 30mm charcoal-like briquettes, the briquettes at the bottom of the furnace are ignited using a gas ^burner .
Roasting was performed while suctioning at a low air flow rate of m ³ /min. After this, the entire lower briquette becomes a fire layer,
When the fire layer has risen to about 2/3 of the briquettes in the upper tier, the roasted ore from the briquettes in the lower tier is discharged, then the briquettes in the upper tier are moved to the lower tier, and new briquettes are filled into the upper tier. Continue roasting,
The stainless steel electric furnace dust was subjected to reduction roasting. Next, 100 kg each of the roasted ore obtained by the above-mentioned reduction roasting device and the briquettes before roasting were melted in a 1 ton Yale-type electric furnace, and the results of clarifying the reduction roasting effect were summarized in the first section. Shown in the table.

【table】

〔Effect of the invention〕

The present invention is constructed as described above, and the device is relatively simple, and furthermore, since it does not require electricity, the operating cost is low, and harmful components are removed from dust and sludge. Ni, Fe,
It has become possible to efficiently convert valuable metals containing Cr into reduced metals. In addition, this device can continuously reduce and roast agglomerated dust and sludge, and
When the roasted dust and sludge are discharged from the roasting equipment, the roasted ore that has been reduced and roasted and turned into metal is dropped at the same time, so there is almost no chance of re-oxidation, and therefore it is effective. It is possible to recover valuable metals.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a reduction roasting apparatus for ordinary steel and special steel dust and sludge according to one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a reduction roasting apparatus for ordinary steel and special steel dust and sludge according to another embodiment of the present invention. 1 shows a partial schematic cross-sectional view of a grate used in a reduction roasting apparatus. Explanation of symbols, 10... Reduction roasting device, 11...
Roasting furnace, 12, 34... Grate, 13... Upper roasting zone, 14... Lower roasting zone, 15... Hood (exhaust hole), 18... Raw material supply port, 22... Grate,
35... Rotating shaft, 36... Opening/closing plate.

Claims (1)

[Scope of Claims] 1. A roasting furnace with an openable and closable grate at the bottom and an exhaust port and a raw material supply port at the top. The respective fire grates are opened and closed sequentially from the lower stage, and the agglomerated dust and sludge introduced from the raw material supply port are sequentially transferred to the lower stage, and the bottom can be opened and closed. A reduction roasting apparatus for ordinary steel and special steel dust and sludge, which is characterized by discharging the above-mentioned dust and sludge roasted from the steel. 2. Ordinary steel according to claim 1, wherein the intermediate grate consists of one or two grate arranged at a predetermined interval in the vertical direction, forming a two- or three-stage roasting zone. and reduction roasting equipment for special steel dust and sludge. 3. The reduction roasting apparatus for ordinary steel and special steel dust and sludge according to claim 1 or 2, wherein the vertical interval between the respective grate is 1000 mm or less. 4. The reduction roasting apparatus for ordinary steel and special steel dust and sludge as set forth in claim 1, 2, or 3, in which the grate in the intermediate portion slides laterally to open and close. 5. Ordinary steel according to claim 1, 2 or 3, in which the intermediate grate comprises an opening/closing plate arranged horizontally at a predetermined interval and having a rotating shaft at one end. and reduction roasting equipment for special steel dust and sludge. 6. The intermediate grate is made of a plurality of coarse grate members, and when the grate members slide laterally, the opening of the grate becomes larger and opens and closes. Reduction roasting equipment for common steel and special steel dust and sludge as described in item 2 or 3.