JPS6221055B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to unfired mini-pellets for sintering raw materials. As is well known, sintered ore is produced by thoroughly mixing and granulating sintering raw materials such as ore powder, coke powder, and limestone, feeding the sintering machine to a sintering machine, and igniting and firing the sintered ore in the sintering machine. ing. In recent years, as one of the raw materials for sintering, various processes in the integrated pig steel process, such as gas ash generated in blast furnaces, collected dust in the sintering process, and dust generated during steel blowing in converters, etc., have been used as sintering raw materials with an average diameter. 2~5mm
Unfired mini-pellets, which are granulated into granules, are actively used. The mini pellets are made of gas ash,
C of sintered ore, coke powder and iron in dust
It will be reused as a FeO source. By the way, in the conventional mini pellets mentioned above, raw materials for adjusting slag components such as serpentine, silica stone, and limestone are added as necessary to raw materials such as gas ash and various dusts, and the mixture is mixed in predetermined proportions and granulated. Since the particle size of the raw material is very small, it is generally granulated using a well-known granulator, but the overall granulation properties of the mini pellets are poor, and the ingredients in the mini pellets are not uniform. It had some serious drawbacks. Regarding the above-mentioned granulation properties, the granulation properties can be improved by increasing the amount of water added or by increasing the amount of bentonite that has a binder function.
There was a problem in that the combustibility of carbon such as gas ash present in the mini pellets deteriorated, and the quality of the sintered ore deteriorated, making it necessary to increase the amount of coke breeze. The present invention was made with the aim of fundamentally solving the problems with the conventional mini-pellets, and its gist is to add moisture to non-charcoal-containing dust that is generated in each step of the integrated pig steel process. This invention relates to non-sintered mini-pellets for use as a sintering raw material, characterized in that the particles are added and granulated, and then blast furnace gas ash is coated on the surface thereof. First, the research history leading up to the present invention will be described. The present inventors conducted research on the gas ash and dust in order to understand the cause of the poor granulation properties, and found that gas ash has extremely poor granulation properties and, conversely, during steel blowing in a converter. It has been confirmed that the converter dust obtained by collecting the generated dust has excellent granulation properties and also functions as a binder.As a result of analyzing the gas ash and dust, their general components are as follows: As shown in the table, it was found that gas ash had poor granulation properties, but contained a lot of carbon c, and naturally had excellent combustibility.

[Table] In Table 1, primary gas ash refers to the gas ash collected by the dry dust collector of the blast furnace, and secondary gas ash refers to the gas ash collected by the wet dust collector of the blast furnace. says. The present invention is based on the above knowledge and as a result of further research, the above-mentioned dust collection duct containing almost no C (hereinafter referred to as non-carbon-containing dust collection dust) is mixed in a predetermined ratio, and water is added to this. It has been found that unfired mini-pellets, which are made by granulating the pellets and then coating the surface with gas ash containing a large amount of carbon, can effectively solve the above-mentioned problems. FIG. 1 is a structural diagram showing an example of a means for producing mini pellets according to the present invention. In the figure, 1 is a bunker that stores non-charcoal-containing collected dust, and 2 is a bunker that stores gas ash. The collected dust stored in the bunker 1 is transferred to the cutting feeder 3.
is cut out into a predetermined amount by a belt conveyor 5.
a, 5b to a granulator 6, where it is granulated while adding moisture and sent as particles 7 to a belt conveyor 5d. On the other hand, the gas ash 8 stored in the bunker 2 is cut out by the cut-out feeder 4, loaded onto the belt conveyor 5d via the belt conveyor 5c, and conveyed. Therefore, the particles 7 are supplied onto a stack of gas ash 8 as shown in FIG. 2, and together with the gas ash 8, they are sequentially sent to subsequent equipment such as a sieving equipment 9 and/or a mixer 10. Gas ash 8
As shown in FIG. 3, the powder is sprinkled and adhered to the entire surface of the particles 7, thereby forming the mini-pellets 11 of the present invention. The means for depositing the gas ash 8 on the surface of the particles 7 is not limited to the above embodiment, but for example, as shown in FIG. 4, the particles 7 and the gas ash 8 are fed to a mixing pelletizer 12, It is also possible to perform the mixing and coating using the mixing pelletizer 12, or to use a well-known drum mixer, although not shown, in place of the mixing pelletizer 12. Furthermore, in order to increase the deposition efficiency at the transfer section of the belt conveyor 5 described above, it is an effective means to provide a chute 13 provided with a plurality of shelves 13a as shown in FIG. As mentioned above, the mini pellets 11 of the present invention are granulated by adding water only to dust with good granulation properties, and the surfaces of the particles 7 containing moisture are coated with gas ash 8, so that The above-mentioned problem of poor granulation properties was solved, gas ash 8 was evenly attached to the surface of particles 7, and the problem of non-uniformity of the components of the mini pellets was also solved. In addition, the gas ash 8 adhering to the surface absorbed moisture from the particles 7, and the strength of the mini pellets 11 was significantly improved. Furthermore, the converter dust has extremely good granulation properties,
The particles 7 are granulated by adding raw materials, collected dust from the sintering process, and in some cases, fine powder raw material for adjusting the slag composition, and adding moisture to this, resulting in extremely excellent granulation properties. This made it possible to reduce the amount of bentonite added. Furthermore, the mini pellets 11 of the present invention are aggregates in which the gas ash 8 having a high C content is not buried in the particles 7, and a layer of the gas ash 8 is formed on the outside and the particles 7 are formed on the inside. Because the dust is contained, the surface of the mini-pellets 11 of the present invention mixed with other sintering raw materials burns immediately in the sintering machine and generates high heat, thereby causing the collected dust to can efficiently melt and initiate a reaction, significantly improving the quality of sintered ore. In the present invention, "containing almost no carbon in the non-charcoal-containing collected dust" means that the C content is below a range that does not adversely affect the granulation properties, and in the experience of the present inventors, the C content is 3 to 3. It was confirmed that the functions of the present invention can be fully exhibited if the content is about 4% or less. Next, specific embodiments of the present invention will be described in detail. EXAMPLE A DL sintering machine with a sintering area of 170 m ² and 183 m ² was used to produce 10,000 tons/day of sintered ore. Table 2 shows the types and amounts of the sintering raw materials used in this example, and Table 3 shows the types of collected dust, gas ash, and amounts used in the mini pellets. The mini pellets of the present invention are made by adding moisture to the collected dust shown in Table 3 and granulating it, and then coating the surface with gas ash. Despite reducing the amount of bentonite in the mini pellets from 2.0% to 1.0%, even with the rotor tap screen,

【table】

[Table] It was confirmed that the -0.5 mm index after sieving for 2 minutes was 10-12% compared to 20-25% for conventional mini pellets, and that it was difficult to break. Furthermore, by blending the mini-pellets of the present invention into the sintering raw material, the coke consumption rate could be reduced by 0.8 kg/ton compared to conventional mini-pellets. As described above, the practical effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 shows one of the means for producing mini pellets of the present invention.
Fig. 2 is an explanatory diagram of particles placed on gas ash on a belt, Fig. 3 is a cross-sectional view of the mini pellets of the present invention, and Figs. 4 and 5 show particles covered with gas ash. It is an explanatory view showing other means of wearing. 1, 2: bunker, 3, 4: cutting feeder,
5, 5a to 5f: belt conveyor, 6: granulator,
7: particles, 8: gas ash, 9: sieving equipment, 10: mixer, 11: mini pellets, 12: mixing pelletizer, 13: chute.

Claims (1)

[Claims] 1. Non-fired mini-pellets for sintering raw material, characterized in that non-charcoal-containing dust generated in each step of the integrated pig steel process is granulated by adding moisture, and then coated with blast furnace gas ash on its surface.