JP5967617B2 - Ferronickel smelting method - Google Patents

Description

  The present invention relates to a ferronickel smelting method, and more specifically, ferronickel that enables efficient operation by preventing operation troubles caused by a sintered ingot generated in a rotary kiln for firing raw material nickel oxide ore. Relates to the smelting method.

  In ferronickel smelting, a nickel oxide ore (hereinafter also simply referred to as “ore”) is used as a raw material, a drying step for drying the ore, and a firing step for firing the dried ore (and partial reduction) are obtained. Ferronickel is produced through a process such as a reductive melting process for reducing and melting calcined ore (calcined ore) (see, for example, Patent Document 1).

  More specifically, in the drying step, a rotary kiln (rotary dryer) is used, and the raw ore containing 35 to 45% moisture is subjected to a drying treatment so that the moisture content is about 32 to 34%. Product (hereinafter referred to as “dry ore”).

  Next, in the calcining step, a rotary kiln is used, and by subjecting the dried ore obtained through the drying step to a calcining treatment, an intermediate (hereinafter, referred to as “the intermediate” in which moisture contained in the dried ore is almost completely removed) It is called “calcined ore”. In this rotary kiln, moisture is removed and partial reduction of the ore is also performed to form a burned ore.

  In the reduction melting step, the produced sinter is put into an electric furnace and reduced and melted to produce ferronickel.

  By the way, in the firing step described above, dry ore is fired in a rotary kiln to produce a burned ore with a particle size of about 10 to 100 mm, and after being measured by a weighing hopper, it is transported to the electric furnace in the subsequent reduction melting step. Is thrown in. At this time, the sinter is put into the electric furnace from the inlet to the electric furnace while being kept in a predetermined range.

  In actual operation, if the temperature at the discharge end of the rotary kiln becomes too high when the sinter is produced, some of the dry ore will melt and adhere to the inner wall of the rotary kiln. As the process continues, it gradually grows to form a ring-like deposit (hereinafter also referred to as “beco”) on the inner wall of the rotary kiln. This beco peels off from the inner wall of the rotary kiln during operation and falls into a lump (hereinafter also referred to as “sintered lump”) having a maximum dimension of about 100 to 500 mm.

  If such a sintered ingot is transferred to the next process in a state where it is mixed with the produced sinter, it will cause clogging in the discharge part of the weighing hopper, the input part to the electric furnace, etc. Trouble that processing operation in the process stops is generated.

  In order to avoid such troubles, the sintered ingot generated in the rotary kiln is separated from the sinter produced by the sieving device provided next to the rotary kiln discharge end, and then the separated sintered ingot is brought to a temperature at which it can be handled. After reducing, the method of returning to the rotary dryer in the drying process and repeatedly treating has been employed.

  However, in the conventional processing of the sintered ingot (repetitive processing), the temperature of the separated sintered ingot is lowered to a temperature at which it can be handled, and further returned to the initial drying process for processing. It was a factor that significantly reduced the performance. In particular, if the sintered mass is repeated in the drying process, etc., the repeated sintered mass will occupy a few percent of the total processing target charged in the rotary dryer or rotary kiln. A few percent of the amount of dry ore treated will not be produced as a burned ore. Therefore, when trying to increase the production amount of ferronickel, it is necessary to take measures such as increasing the amount of fossil fuel used.

JP 2011-225903 A

  Therefore, the present invention has been proposed in view of such circumstances, and in ferronickel smelting, the actual yield of sinter can be improved while avoiding troubles such as operation stoppage, and ferronickel production can be increased. An object of the present invention is to provide a method for smelting ferronickel.

As a result of intensive investigations to achieve the above-mentioned object, the present inventors have performed a firing process while maintaining the sinter temperature at the discharge end of the rotary kiln within a predetermined range, and sintered ingots generated from the rotary kiln. It has been found that by performing crushing treatment with grizzly and crushing treatment with crusher , repeated processing to the drying process of the sintered ingot is unnecessary, and the actual yield of the sinter can be improved, and the present invention is completed. I let you.
Note that the term “crushing” as used herein refers to breaking or unraveling a solidified lump. The same applies throughout the following.
Further, “pulverization” here is one of operations for crushing a substance to produce “powder”. The same applies throughout the following.

That is, the smelting method of ferronickel according to the present invention includes a step of firing a nickel oxide ore by a rotary kiln to produce a burned ore, and a step of transferring the obtained burned ore to an electric furnace and reducing and melting it. A smelting method of ferronickel, in which a calcination process is performed by controlling a calcination temperature at a discharge end of the rotary kiln in a range of 800 to 900 ° C., and a sinter formed in the rotary kiln is produced. The sintered mass is crushed and grinded with grizzly and / or the sintered mass is crushed with a crusher and sieved, and the sieving material obtained after sieving is obtained. It is characterized by being transferred to an electric furnace.

  Here, in the above-described ferronickel smelting method, it is preferable that a sieve opening used for the sieving is 10 to 100 mm.

Moreover, it is preferable to perform the said crushing and sieving process with respect to the sieve top obtained by sieving, after performing the said crushing and sieving process the sintered lump separated from the sinter.

Further, the process of sieving the crushed said grilled Yuikatamari, in the process of sieving the pulverized the sintered Yuikatamari may be carried out while maintaining the temperature of該焼Yuikatamari in the range of 600 to 900 ° C. Is preferred.

  Moreover, it is preferable to transfer the sieving material obtained after sieving to an electric furnace by a transfer facility that has been subjected to a heat treatment.

  According to the smelting method of ferronickel according to the present invention, it is possible to improve the actual yield of sinter, while preventing operational troubles caused by sintered ingots generated from a rotary kiln, and increase the amount of energy used such as coal and heavy oil. It is possible to increase the production of ferronickel without causing it.

It is a schematic block diagram of the rotary kiln which performs the baking process with respect to an ore. It is a figure for demonstrating the flow of conveying the sinter discharged | emitted from the rotary kiln to an electric furnace, and the flow of a process with respect to the sintered ingot discharged | emitted from the rotary kiln.

  Hereinafter, a specific embodiment of the ferronickel smelting method according to the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary of this invention, a change is possible.

≪About ferronickel smelting process≫
In the smelting method of ferronickel according to the present embodiment, a raw nickel oxide ore is calcined by a rotary kiln to produce a calcined ore (calcining process), and the obtained calcined ore is carried into an electric furnace. And a step of reducing and melting (reducing and melting step).

<Baking process>
In the firing process, dry ore obtained by pre-drying nickel oxide ore, which is a smelting raw material, is subjected to a firing process using the combustion heat of fuel to remove moisture almost completely and perform partial reduction, followed by firing. Produces ore (calcined ore). The baking process in this baking process is performed by a rotary kiln.

  FIG. 1 is a schematic configuration diagram of a countercurrent heating type rotary kiln that performs a firing process on dry ore. In the rotary kiln 1 shown in FIG. 1, dry ore obtained by removing a part of moisture adhering to the nickel oxide ore by a dryer (rotary dryer) in the drying step of the previous step is charged as a raw material. Then, using the combustion heat of fossil fuel, the moisture of the dried ore is almost completely removed and fired, and a partial reduction treatment is performed to discharge the fired ore.

Although it does not specifically limit as nickel oxide ore (nickel oxide ore), Garnilite ore etc. are used preferably in ferronickel smelting. As a typical composition of garnierite ore, Ni grade is 2.1 to 2.5% by weight in terms of dry ore, Fe grade is 11 to 23% by weight, MgO grade is 20 to 28% by weight, and SiO ₂ grade is 29 to 39% by weight, CaO grade is less than 0.5% by weight, and loss on ignition is 10 to 15% by weight.

  In the rotary kiln 1, dry ore is charged from its charging end 1A (hereinafter also referred to as "rotary kiln charging end 1A"). As described above, the dry ore charged into the rotary kiln 1 is a raw ore that has been pre-dried by a drier and part of the adhering water removed, and the amount of water is about 25 to 35% by weight as a guide. is there.

  Further, in the rotary kiln 1, a burner 2 is provided at the discharge end 1B (hereinafter also referred to as “rotary kiln discharge end 1B”), and fossil fuel such as heavy oil added from the discharge end 1B is transferred by the burner 2. Burned and burned. The dry ore charged from the rotary kiln charging end 1 </ b> A and moving through the rotary kiln 1 is baked by the countercurrent by the combustion heat generated by the combustion to become a calcined ore. The sinter produced by firing the dried ore in this way has a particle size of about 10 to 100 mm, and is discharged from the slag 3 for discharging the sinter ore provided continuously at the discharge end 1B. Then, it is transported to a furnace bin provided in the upper part of the electric furnace by a transport facility.

  In addition, as shown in FIG. 1, in the continuous part of the rotary kiln discharge end 1B, the sinter with a particle size of about 10 to 100 mm and the sintered ingot (particle size of about 100 to 500 mm) generated in the rotary kiln are separated. A rooster (sieving device) 4 is provided. Therefore, the slag discharged from the rotary kiln discharge end 1 </ b> B passes through the rooster 4 and is then placed on the transport facility via the slag 3 for discharging the sinter. On the other hand, the sintered ingot discharged from the discharge end 1B together with the sinter is separated from the sinter by remaining on the rooster 4 because of its large particle size, and baked through the chute 11 for discharging the sintered ingot. It is transferred to a lump processing facility. The separation of the sinter and the sintered ingot and the processing of the sintered ingot will be described in detail later.

<Reduction melting process>
Next, in the reduction melting step, the sinter produced in the firing step described above is transported into an electric furnace (reduction furnace) for reduction melting. Specifically, after the produced sinter is stored in a furnace bin, it is placed in an electric furnace such as a three-phase AC electrode type circular electric furnace through a slag chute connected to the furnace bin. The sinter is supplied and reduced and melted to form metal (crude ferronickel) and slag. The formed metal and slag are separated into a metal layer and a slag layer due to a specific gravity difference.

  In the present embodiment, the sintered ingot based on the bevel formed in the rotary kiln is also put into the electric furnace together with the sinter by performing a predetermined treatment. Details will be described later.

≪About sintered ingot≫
Here, in the actual operation of ferronickel smelting, when the calcination process is performed in the rotary kiln and the sinter is produced, a part of the raw dry ore melts and adheres to the inner wall of the rotary kiln, and the operation is continued. The so-called beco is formed on the inner wall of the rotary kiln. This beco peels off from the inner wall of the rotary kiln during operation, and is discharged from the rotary kiln as a sintered lump having a maximum dimension of about 100 to 500 mm. When this sintered ingot is transferred to the next step together with the sinter, it causes clogging at, for example, the discharge port portion of the weighing hopper and the input port portion to the electric furnace. Therefore, conventionally, the discharged sintered ingot was returned to the rotary dryer in the drying process, and repeated processing was performed.

  However, in such a conventional operation, repeated sintered ingots occupy several percent of all treatment objects (total ore treatment amount) charged in a rotary dryer or rotary kiln. And since the repeated processing of the sintered ingot is repeated while continuing the operation of ferronickel smelting, several percent of the dry ore processing amount processed in the rotary kiln is obtained as calcined ore. No proportion. In other words, it is not possible to produce a burned ore at a rate of 100% with respect to the amount of ore treated (the actual yield of burned ore cannot be 100%). Furthermore, in order to process repeated sintered ingots in a rotary kiln, it is necessary to increase the amount of energy used for coal, heavy oil, etc., and only a few percent of the total amount of the sintered ingot occupies energy. The basic unit will increase.

≪Smelting method of ferronickel≫
Therefore, in the ferronickel smelting method according to the present embodiment, in the sintering process, the firing temperature of the discharge end 1B of the rotary kiln 1 is maintained in the range of 800 to 900 ° C. to perform the firing treatment, and the rotary kiln 1 The sintered ingot generated inside is separated from the produced sinter, and the sintered ingot is crushed by grizzly and screened, and / or the sintered ingot is crushed by crusher and screened. The sieving material obtained after sieving is conveyed to an electric furnace. More specific description will be given below.
In addition, it is preferable to use the tilt type grizzly with a vibrator having a sieve surface with an appropriate opening as the above-mentioned grizzly. The same applies throughout the following.
Moreover, the process which grind | pulverizes with the above-mentioned crusher and sifts, for example, grind | pulverizes with a bucket type jaw crusher (made by Meccanica Breganzese), and sifts again using the grizzly with a vibrator of an appropriate opening. The same applies throughout the following.

<Temperature control in firing process>
In the ferronickel smelting method according to the present embodiment, in the sintering process, it is important to perform the firing process by controlling the calcination temperature of the rotary kiln discharge end 1B in the range of 800 to 900 ° C. As a method for controlling the sinter temperature at the rotary kiln discharge end 1B, for example, it is performed by appropriately adjusting the supply amount of fossil fuel such as coal or heavy oil supplied to the burner 2 provided at the discharge end 1B. it can.

  In the firing process in the rotary kiln 1, by setting the sinter temperature at the discharge end 1B to 800 ° C. or higher, the moisture contained in the raw dry ore can be completely removed, and the sinter is reduced and melted in an electric furnace. It is possible to prevent the occurrence of steam explosion. Further, by setting the calcination temperature at the discharge end 1B to 900 ° C. or less, the rotary kiln discharge end 1B can be prevented from being excessively heated, that is, the formation of a large amount of sinter can be prevented. be able to.

  And by performing a baking process so that a calcination temperature may be in the range of 800-900 degreeC in this way, the generation rate of a sintered ingot can be reduced to about 3% on the average with respect to the amount of rotary kiln ores processed. it can. Thereby, while being able to isolate | separate effectively the sintered lump and calcination which are discharged | emitted, it becomes possible to perform the crushing and grinding | pulverization process mentioned later efficiently.

  In addition, as mentioned above, when the calcination temperature of the discharge end 1B is less than 800 ° C., moisture remains in the calcination, which may cause a steam explosion when charged in the electric furnace. Therefore, it is not preferable. Further, when the sinter temperature exceeds 900 ° C., a large amount of sintered ingots are formed and it becomes difficult to separate from the sinter, and in the processing of the sintered ingots described later, damage or wear of processing equipment is caused. Will become violent, and it is necessary to repeat the process of repeatedly charging the drying process.

<Separation of sinter and sintered ingots and treatment of sintered ingots>
In the ferronickel smelting method according to the present embodiment, the sintered ingot generated in the rotary kiln is separated from the produced sinter, and the sintered ingot is crushed and sieved, and / or Alternatively, the sintered lump is crushed and sieved, and the sieving material obtained after sieving is conveyed to an electric furnace.

  Here, in FIG. 2, the rotary kiln used in the sintering process, the equipment for transporting the burned ore discharged from the rotary kiln to the electric furnace used in the reduction melting process, and the sintered ingot generated in the rotary kiln The block diagram of processing equipment is shown. In the smelting method of ferronickel according to the present embodiment, processing for the sintered ingot separated from the sinter is performed using equipment as shown in FIG. Hereinafter, processing for the sintered ingot will be described while explaining each facility. In addition, description of the structure of a rotary kiln is abbreviate | omitted with the description mentioned above suitably.

(Lostre)
As shown in FIG. 2, the discharge end 1 </ b> B of the rotary kiln 1 is provided with a rooster 4 at a continuous portion (position) thereof. The rooster 4 is made of, for example, an iron grid having an opening of about 100 mm. The calcined ore (particle size 10 to 100 mm) obtained by firing in the rotary kiln 1 passes through the rooster 4 and is transferred to the weighing hopper 5 via the chute discharge chute 3 connected to the discharge end 1B. Is done.

  The rooster 4 has an effect of separating the sinter discharged from the rotary kiln 1 and the lump (sintered lump) based on the bevel generated in the rotary kiln 1. As described above, the rooster 4 is composed of a lattice having an opening of about 100 mm, and allows the burned ore with a particle size of about 10 to 100 mm to pass through, while being discharged from the rotary kiln 1 together with the burned ore with a particle size of 100 to 500 mm. The sintered ingot of the extent (maximum dimension) is left on the rooster 4 to separate from the sinter. As a result, the sintered ingot having a large particle size is prevented from being transferred together with the calcined ore to the measuring hopper 5 via the chute discharging chute 3, and clogging by the sintered ingot occurs at the discharge port of the measuring hopper 5 or the like. Can be prevented. The sintered ingot separated from the sinter is transferred to a sintered ingot processing facility 10 to be described later via a sintered ingot discharge chute 11 connected separately from the chute discharge chute 3 at the rotary kiln discharge end 1B. Be transported.

(Weighing hopper)
The weighing hopper 5 stores the sinter transported through the slag 3 for discharging the sinter, and measures the stored sinter into a predetermined amount and transfers the sinter to the transport facility through the discharge port. The weighing hopper 5 cuts out a predetermined amount of stored sinter at regular intervals in accordance with the supply of new sinter discharged from the rotary kiln 1.

  In the weighing hopper 5, when trouble such as clogging occurs at the discharge port, the cutting of the sinter at a certain interval is not smoothly performed, and the sinter exceeding the storage limit in the hopper 5 is retained. End up. As a result, the supply of the mine from the rotary kiln 1 is stopped, that is, the operation of the rotary kiln 1 is forced to stop. In this regard, in the present embodiment, the firing (mining temperature) at the rotary kiln discharge end 1B is maintained within a certain range to perform firing treatment, and the generation of sintered ingots that are the main cause of blockage is minimized. Further, a rooster 4 is provided at the discharge end 1B to separate the sinter and the sintered ingot. Thereby, obstruction | occlusion in the measurement hopper 5 can be prevented effectively, and generation | occurrence | production of the trouble which reduces remarkably operation efficiency, such as the operation stop of the rotary kiln 1, can be prevented.

(Transport equipment)
The calcined ore from which a predetermined amount has been cut out from the weighing hopper 5 is then placed on a transport facility and transported to an electric furnace used in a reduction melting process. Although it does not specifically limit as a conveyance equipment which conveys a sinter to an electric furnace, For example, the equipment which can convey a sinter at a fixed speed, such as equipment which consists of a container for a sinter and a crane which raises and lowers the container, can be used. . Specifically, for example, this transport facility places the sinter in a container for sinter and transports it to a destination electric furnace, and then squeezes the sinter to a furnace bin provided at the top of the electric furnace by a crane. Lift and store in the furnace bin.

  Further, in this transfer facility, at the point to the electric furnace, the crushed and pulverized product of the sintered ingot discharged from the sintered ingot processing facility 10 described later (the same as “under sieve” in the following description) ). The sinter is transported to the electric furnace together with the crushed and pulverized material. It should be noted that the crushed and pulverized material of the sintered ingot is not limited to being transported (combined) together with the calcined ore to the electric furnace by the same transport equipment as the calcined ore, but is connected to the sintered ingot processing facility described later You may make it convey to an electric furnace by providing the conveyance equipment for crushing and grinding | pulverization of a sintered lump.

  Moreover, it is preferable that this conveyance equipment is the equipment which performed the heat retention process in order to hold | maintain the pulverized and pulverized material of the sinter or sintered lump which is a conveyed product. Here, when the sinter or the like transported through the transport facility is put into the electric furnace in the reduction melting process, an ore layer is formed in the furnace, and it becomes metal and slag by the reduction melting in the electric furnace. . At this time, when the temperature of the sinter or the sintered ingot pulverized / disintegrated product is lowered, the temperature in the furnace is lowered to adversely affect the reduction melting. For this reason, in transporting sinter or the like, it is preferable to transport the slag ore discharged from the rotary kiln by a transport facility that has been subjected to heat insulation so that it can be put into an electric furnace while being held at a high temperature. . Specifically, it is preferable to carry in a state where the temperature of the sinter or the like is kept in the range of about 600 to 900 ° C.

  There is no particular limitation on the heat insulation treatment applied to the transport equipment, but for example, the transport equipment such as a chain conveyor is used as a sealed space, and the outer periphery is covered with a heat insulation jacket or the like, or a heat exchanger is installed. Keep the temperature of the sinter or the like in a certain range.

(Sintered lump processing equipment)
The sinter lump treatment facility 10 is a facility for processing the sinter lump immediately after being separated from the sinter by the rooster 4 provided at the discharge end 1 </ b> B of the rotary kiln 1. Specifically, as shown in FIG. 2, the sintered lump processing equipment 10 is connected to the discharge end 1B and discharges and transfers the sintered lump chute 11 for discharging the sintered lump and the discharged sintered lump. And a receiving hopper 13 for receiving the sieved material that has been crushed, pulverized, and sieved by the processing facility 12. In this sinter lump processing equipment 10, the sinter lump that has been separated from the sinter is configured and arranged so that it can be subjected to a pulverization process, a pulverization process, and the like. The goods can be transported and put into the electric furnace immediately. Thereby, the fall of the temperature of a sintered lump can be suppressed.

  The sintered mass discharge chute 11 is a pipe connected to the discharge end 1B side of the rotary kiln 1, and transfers the sintered mass having a maximum size of about 100 to 500 mm separated by the rooster 4 to the processing equipment 12. It is piping for doing.

  The processing facility 12 is composed of, for example, a pulverization processing facility or a pulverization processing facility, and may perform a process of pulverizing and sieving the sintered mass and / or a process of pulverizing and sieving the sintered mass. It is possible. In addition, in the block diagram of FIG. 2, the processing equipment (crushing processing equipment) for performing the process which crushes a sintered lump and sieves is shown as an example.

  Specifically, the crushing treatment equipment is not particularly limited as long as it has durability against temperature, can crush the sintered ingot, and can screen the crushed material. For example, from the viewpoint of the crushing effect, it is preferable to use a tilting grizzly with a vibrator. This tilting grizzly with a vibrator includes a vibrator for applying vibration to the sintered ingot and a sieve surface having an opening of about 100 mm or less, and the sintered ingot is crushed by vibration and crushed. The pulverized product having a size of 100 mm or less is separated by a sieve (under sieve).

  The pulverization equipment is not particularly limited as long as it has durability against temperature, can sinter the sintered ingot, and can screen the pulverized product. For example, as the pulverizing means, a bucket type jaw crusher can be used. According to such a bucket-type jaw crusher, even a high-temperature sintered lump can be easily pulverized by the jaw provided on the bucket at the tip of the arm, and the temperature of the sintered lump is maintained. Can be processed as is. In addition, a pulverized product having a desired size can be easily obtained even for a sintered ingot that requires a long time in the crushing treatment.

  Moreover, as a sieving means provided in the pulverization processing facility, the above-described grizzly can be exemplified. Thus, as a pulverization processing facility, a pulverized product (under sieve) of about 100 mm or less can be produced from a sintered lump having a large particle diameter by combining the pulverizing unit and the sieving unit. it can.

  The sieve openings used for sieving in the above-described pulverization processing equipment and pulverization processing equipment are preferably about 10 to 100 mm. When the sieve opening is less than 10 mm, the ratio of the powder mixed in the under-sieving material obtained after sieving increases, which causes dust generation during the conveyance. On the other hand, when the mesh opening of the sieve exceeds 100 mm, an under sieve having a maximum dimension larger than 100 mm will be transported together with the sinter, resulting in troubles such as blockage at the entrance to the electric furnace, for example. There is a possibility to make it.

  Further, in this treatment facility 12, a pulverization treatment facility and a pulverization treatment facility are continuously provided, and after performing a process of pulverizing and sieving the sintered ingot, a sieve obtained by sieving is obtained. It is preferable to perform a process of pulverizing and sieving the upper product. Specifically, for example, a tilting grizzly with a vibrator is provided as a crushing treatment facility, and the sintered lump discharged from the sintered lump discharge chute 11 is crushed and sieved with a sieve surface having an opening of about 100 mm. After that, the sieved product is pulverized by, for example, a bucket type jaw crusher. Thereby, a sintered ingot with a large particle diameter can be processed more effectively to the same size as that of sinter.

  Further, in the processing equipment 12 for pulverizing and sieving the sintered ingot, and for pulverizing and sieving the sintered ingot, the temperature of the sintered ingot to be processed is in the range of 600 to 900 ° C. It is preferable to carry out in a state of being held. Thereby, also when thrown into the electric furnace the crushed and pulverized product (under sieve) of the sintered ingot, it is possible to prevent a temperature drop in the furnace. Specifically, for example, each device may be arranged so that the sintered lump immediately after being separated from the calcined ore at the rotary kiln discharge end 1B can be subjected to pulverization treatment or pulverization treatment. In addition, the treatment facility 12 itself may be subjected to a heat retention treatment so that the treatment can be performed under a certain temperature condition (heat retention condition).

  The receiving hopper 13 receives and stores the sieving material obtained by crushing, pulverizing, and sieving the sintered ingot in the processing equipment 12 described above. As long as the receiving hopper 13 is made of a material having durability against temperature, its shape, size, and the like are not particularly limited.

  As shown in FIG. 2, the receiving hopper 13 has a screw conveyor 14 connected to a discharge port thereof, and the screw conveyor 14 is connected to a transport facility for transporting the sinter. Therefore, a predetermined amount of under-sieving material (sintered crushed and pulverized material) cut out by the receiving hopper 13 is placed on the conveying equipment via the screw conveyor 14 and conveyed to the electric furnace. The receiving hopper 13 is connected to the weighing hopper 5 that stores the baked ore and measures a predetermined amount, and the sieving material in the receiving hopper 13 is stored in the weighing hopper 5 together with the baked ore. Also good. Alternatively, the receiving hopper 13 may be connected to a transport facility different from the transport facility for transporting the burned ore, and the undersieved material in the receiving hopper 13 may be transported alone to the electric furnace.

  As described above, in the smelting method of ferronickel according to the present embodiment, while performing the firing treatment while maintaining the calcination temperature at the discharge end 1B of the rotary kiln 1 in the range of 800 to 900 ° C., from the rotary kiln 1 The resulting sintered mass is subjected to pulverization and pulverization, and sieved, and the sieving material is conveyed to the electric furnace together with the sinter.

  According to such a method, the process of repeating the discharged sintered mass for the drying step or the like as in the prior art becomes unnecessary. Therefore, compared with the conventional method which repeated the whole quantity of the sintered ingot, the actual yield of a sinter can be improved. In addition, since the sintered ingot is not repeated, the amount of energy used for fossil fuels and the like in the rotary kiln can be reduced.

  And since the actual yield of a sinter can be improved in this way, the production of ferronickel can be increased without increasing the amount of energy used such as coal and heavy oil.

  Examples of the present invention will be described below in comparison with comparative examples. In addition, this invention is not limited by these Examples.

[Example 1]
Using a rotary kiln with a length of 105m and an inner diameter of 4.3m used in ferronickel smelting, the dried ore obtained by drying the nickel oxide ore is calcined and partially reduced. Produced. The calcining operation in this rotary kiln was performed for 24 hours under the conditions of ore throughput: 80.0 t / h, moisture in the ore (dry ore): 18 to 28% by weight, and rotary kiln rotation speed: 0.7 to 1.4 rpm. . Moreover, it operated so that the calcination temperature in the discharge end of a rotary kiln was kept in the range of 800-900 degreeC.

  As a result of this operation, an average of 70.0 t / h sinter and a time average of 2.1 t / h sintered ingot were discharged. The sinter and the sintered ingot were separated by a rooster provided at the discharge end of the rotary kiln, and each was discharged separately.

  Next, the discharged 2.1 t / h sintered ingot was crushed and sieved using a tilting grizzly vibrator with a sieve having an opening of 100 mm. As a result of this treatment, 0.9 t / h of the crushed material under the sieve (under-sieved material) obtained by pulverizing the sintered ingot was obtained in terms of time average. The obtained under sieve was stored in a receiving hopper and then transferred to a weighing hopper via a screw conveyor and a chain conveyor.

  On the other hand, 1.2 t / h of the sintered mass on the sieve in the tilting type grizzly with vibrator (the article on the sieve) was obtained on a time average. Therefore, the sieve top, that is, the sintered ingot having a maximum dimension larger than 100 mm, is pulverized by a bucket-type jaw crusher (manufactured by Meccanica Breganzese) and sieved again using a grizzly with a vibrator having an opening of 100 mm. did. As a result, the entire amount of the treated sintered ingot was obtained as an undersieved material. The obtained under sieve was stored in a receiving hopper and then transferred to a weighing hopper via a screw conveyor and a chain conveyor.

  As described above, by transferring the entire amount of sintered ingot discharged at an average time of 2.1 t / h to the weighing hopper, 72.1 t / h can be put into the electric furnace together with the sinter. As a result, it was possible to improve the actual yield of the sinter, and to increase the production of ferronickel. Moreover, the discharge ratio of the sintered ingot could be suppressed to about 3% on average, and the processing for the sintered ingot could be performed efficiently.

[Comparative Example 1]
In Comparative Example 1, after a 70.0 t / h sinter and a 2.1 t / h sintered ingot were obtained from the discharge end of the rotary kiln, the sintered ingot was repeated in the drying process in ferronickel smelting. (Repeatedly charged into the rotary dryer used in the drying step.)

  As a result, only 70.0 t / h of sinter was able to be put into the electric furnace. Moreover, since the process which repeats the discharged | sintered ingot to a previous process was performed continuously, the actual yield of a sinter could not be raised.

[Comparative Example 2]
In Comparative Example 2, the operation was performed in the same manner as in Example 1 except that the firing process was performed so that the calcination temperature at the discharge end of the rotary kiln was 700 to 780 ° C.

  As a result, it was possible to put the sintered ingot into the electric furnace together with the sinter by pulverizing, crushing, and sieving the discharged sintered ingot. Considering the risk of a steam explosion when entering the factory, we had to stop the operation. This is considered to be because the moisture in the dried ore was not sufficiently removed by performing the firing treatment so that the calcination temperature became 700 to 780 ° C.

[Comparative Example 3]
In Comparative Example 3, the operation was performed in the same manner as in Example 1 except that the firing treatment was performed so that the calcination temperature at the discharge end of the rotary kiln was 920 to 1000 ° C.

  As a result, since the sintered lump of the amount greatly exceeding the sieving capacity of the rooster provided continuously at the discharge end of the rotary kiln was generated, the sintered lump was piled up on the rooster, and the sinter and sintered lump Could not be separated effectively. For this reason, operation had to be stopped.

  1 rotary kiln, 1A rotary kiln charging end, 1B rotary kiln discharge end, 2 burner, 3 slag discharge chute, 4 rooster, 5 metering hopper, 10 sintered lump treatment equipment, 11 sintered lump discharge chute, 12 treatment Equipment, 13 receiving hopper, 14 screw conveyor

Claims (5)

A smelting method of ferronickel comprising a step of firing a nickel oxide ore by a rotary kiln to produce a sinter, and a step of transporting the obtained sinter to an electric furnace and performing reductive melting,
The calcination temperature at the discharge end of the rotary kiln is controlled within a range of 800 to 900 ° C., and the sinter formed in the rotary kiln is separated from the produced sinter. A process of pulverizing and sieving with grizzly and / or a process of crushing and sieving the sintered ingot with a crusher, and transporting the sieving material obtained after sieving to an electric furnace Ferronickel smelting method.   2. The ferronickel smelting method according to claim 1, wherein a sieve opening used for the sieving is 10 to 100 mm. The sintered mass was separated from the sintered ore after the processing of the disintegrated sieving, claims and performs a process of sieving the pulverized the obtained sieved quality goods and sieved Item 3. A method for smelting ferronickel according to Item 1 or 2. Process of sieving the crushed said grilled Yuikatamari, in the process of sieving the pulverized the sintered Yuikatamari is characterized by performing Maintaining the temperature該焼Yuikatamari in the range of 600 to 900 ° C. The method for smelting ferronickel according to claim 1.   The smelting method for ferronickel according to claim 4, wherein the under-sieved material obtained after sieving is transported to an electric furnace by a transport facility subjected to heat insulation.

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