JPH0136880B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing coke briquette for a steelmaking furnace, the purpose of which is to increase the temperature of hot metal when refining steel in a converter. (Problem to be solved by the invention) Conventionally, in an integrated steelworks, blast furnace molten pig iron at about 1350℃ is processed into coal, fluorite, manganese ore, ferroalloy, etc. in a converter (hereinafter, a converter will be described as an example of a steelmaking furnace). In this refining process, impurities such as silicon, phosphorus, and carbon are removed from the hot metal by blowing oxygen gas into it, but during such refining, the temperature inside the furnace rises due to oxidative exothermic reactions such as during desiliconization. To avoid this, the optimum temperature was maintained by charging scrap iron such as iron ore or steel cutting scraps generated in the processing process after steel manufacturing, and utilizing the heat absorbed by the melting or reaction. Therefore, the yield of iron for the steelworks as a whole was good, and it was easy to increase the amount of steel produced in the converter when there was a shortage of hot metal. However, in the latest optimal steelmaking method, the above-mentioned desiliconization and dephosphorization in the furnace are performed outside the furnace by blowing iron oxide, lime, etc. together with an inert gas to suppress the amount of slag generated, and increase production by shortening the converter refining time. Ex-furnace desiliconization and phosphorization methods have been implemented with the aim of In refining in a converter, the amount of iron ore or scrap iron charged is limited, resulting in a decrease in the overall iron yield within the steelworks, an increase in scrap iron inventory within the steelworks, or an inability to respond to hot metal shortages. There were some questions about whether it was possible. On the other hand, the strong coking coal coke material (hereinafter referred to as coke powder) referred to in the present invention is made by crushing and sifting hard coke made by carbonizing strong coking coal mainly for use in blast furnaces. The coke powder under the sieve that is supplied to the blast furnace has few uses compared to the amount generated and has a small bulk specific gravity, so as the amount of inventory increases gradually, a large storage area is required. It was difficult to manage. Although the coke powder was used to raise the temperature of hot metal in a converter, it is easy to run out of supply due to shelving in the hopper before charging into the converter.
Furthermore, in the furnace, the thermal efficiency is about 50% due to scattering loss due to upward flow in the furnace, resulting in a large energy loss, and therefore, it has become necessary to agglomerate the coke powder. In addition, the steelmaking slag powder used in the present invention is produced by crushing, sieving, magnetic separation, etc., steelmaking slag generated in converter refining, for example, from the viewpoint of effective utilization.
Iron is recovered and the slag is used for roadbed material, aggregate, etc., and dust collectors are installed to collect the dust generated in each process as an environmental measure. This collected dust has a particle size of 0.15
mm (100 mesh) or less with an average particle size of 0.03mm
Because it is in the form of a dry, fine powder, there is currently no use for it, and it is being dumped after taking measures to prevent it from scattering. (Means for Solving the Problems) The present invention provides a method for producing coke briquettes for steelmaking furnaces, which is primarily intended for use in increasing temperature in converters, in order to meet the above-mentioned problems and demands. The gist is that the viscosity composition of strongly coking coal coke powder should be 3 mm or less80
The coke powder is sized so that more than 20 parts by weight and the remaining part is less than 20 parts by weight exceeds 10 to 3 mm, and then 5 to 20 parts by weight of steelmaking slag powder is added to 100 parts by weight of the sized coke powder dry weight,
Add 0.15 to 2 parts by weight of an organic binder on a solid basis, adjust the water content to 6 to 12 parts by weight based on 100 parts of the dry weight of the mixture, and mix.The resulting mixture is subjected to continuous compression. This is a method for producing coke briquette for steelmaking furnaces, which is characterized by forming it with a forming machine and aerating it. The present invention will be explained in more detail with reference to the drawings. FIG. 1 is a process diagram of an embodiment showing the manufacturing method of the present invention. The coke powder whose moisture content has been detected in advance (indicates the weight ratio of moisture to 100 parts of dry weight, hereinafter referred to simply as parts by weight) is cut into fixed quantities by the receiving hopper 1 and the lower belt feeder 2. It is sent to a vibrating conveyor 4 with a drying device by a belt conveyor 3, and the moisture content is reduced to about 8 parts by weight, and it is sieved through a 5 mm sieve screen. It is temporarily placed in a sub-hopper 7 via a conveyor 6, and is intermittently and quantitatively supplied to a mixer 8. On the other hand, the steelmaking slag powder and the organic binder are cut out from the hopper 7, feeder 10, tank 11, and quantitative meter 12 into the mixer 8 according to the amount of coke powder, and mixed, and the resulting mixture is continuously compressed. It is supplied to a molding machine 13 to continuously form coke briquettes. The formed coke briquette is passed through a net conveyor 14 at the bottom, where unformed materials are sieved.
The products are stored in a finished product box 16 by a belt conveyor 15.
The unsieved material of the net conveyor 14 is sent back to the roll compression molding machine 13 by the fin conveyor 17, and
Compression molding is carried out together with the mixture. 18 is a hot air generator, and 19 is an exhaust fan. Shosei product box 16
is a breathable material with a net-like bottom surface.
The coke briquette is then aerated and cured until it has a strength suitable for charging into a converter. In the method of the present invention, coke powder is dried to a water content of about 8 parts by weight because coke is porous, and the water content is normally reduced to 13 to 17 parts by water cooling during coke production or by water absorption in an outdoor storage area. If the weight part is high and the moisture content is high, the compression will be relaxed due to moisture during molding, resulting in weak briquettes, and the surface tension on the roll form surface of the continuous compression molded material will adsorb the briquettes, making mold deformation worse. This tends to cause molding defects, which is a factor that reduces molding yield. In addition, an organic binder is added to maintain the strength immediately after molding, but in order to overcome the drawbacks such as inhibiting the caking effect immediately after molding because the binder is diluted by excess water, moisture adjustment is used in the present invention. Requires. The appropriate range of moisture content in the present invention varies depending on the scale of the converter factory and the required strength of the briquette. For example, the strength is determined by the drop during transportation or charging, and it may be strong enough to withstand the drop. Therefore, the compression force during molding is approximately 600Kg/cm ² ~1600Kg/
If it is in the cm ² range, the briquette can be used normally, so the porosity of the product under this condition is used as the standard for the entire moisture range, and in the examples, the moisture of the binder added separately is also taken into account. decide. Satisfactory briquette strength can be obtained if the water content is within the range of 6 to 12 parts by weight as defined in the present invention. Also, the moisture content is 6
If the amount is less than parts by weight, wet coke powder may be added and the method of the present invention may be followed. Next, the reason why the briquette is sieved into 5 mm pieces using the vibrating conveyor 4 is that the strength of the briquette after compression molding is affected not only by the moisture content but also by the particle size structure of the raw material, so the particle size structure is adjusted according to the customer's briquette strength. This is an example. Because coke powder is stored in piles at storage sites, the particle size distribution is segregated, and coarse particles tend to break during compression molding due to the high porosity and weak bonding force between particles. Therefore, the molding yield is poor and the briquette tends to be weak. Therefore, in order to make briquettes with uniform strength, it is necessary to sieve to obtain a uniform and optimal particle size composition, and particles of 3 mm or less are considered coke powder.
If it exceeds 80 parts by weight per 100 parts by weight, it exceeds 3 mm ~ 10
Even if there are mm ones, the influence of the briquette strength is small due to the interference effect of the powder. If the particle size exceeds 10 mm, the strength of the briquette may be weakened due to the above-mentioned factors during compression molding, so in the present invention, the particle size is set not to exceed 10 mm. FIG. 3 shows that coke on the sieve with a particle size of 5 to 10 mm collected by the vibrating conveyor 4 of one embodiment is mixed in the bottom of the sieve.
FIG. 3 is a diagram showing the relationship between the molding yield and the crushing strength immediately after molding when molding is performed by changing the distribution of particle sizes of 3 mm or less. In this experiment, sieved coke of 5 mm or more was mixed and supplied from the conveyor 6 shown in Fig. 1 of the present invention, and 10 parts by weight of dry steel slag fine powder of 100 mesh or less was added to 100 parts by weight of dry coke powder, and Add and mix an aqueous lignin solution equivalent to 2 parts by weight in terms of dry solid content, and mold according to the process shown in Figure 1.
The weight percentage of the products that were completely kept in shape by collecting all the products discharged from the belt conveyor 15 for a certain period of time was taken as the yield, and the results of measuring the crushing strength of several products are shown in FIG. Note that the water content before the molding was about 9 parts by weight. The compression force of the continuous compression molding machine 13 is 1000Kg/ ^cm2 , and the shape of the briquette is 21mm thick.
It was formed into a charcoal shape with a width of 35 mm and a length of 46 mm. In FIG. 3, section A indicates the area of molding yield, and section B indicates the area of crushing strength. Figure 3 shows that in order to facilitate handling immediately after molding, it is necessary to ensure a crushing strength of 3.5 kg or more, and therefore the ratio of particles with a diameter of 3 mm or less to 100 parts by weight of coke powder must be 80 parts by weight or more. It turns out that there is something. Note that the crushing strength is the pressing load when the briquette is crushed by pressing the spherical surface, since the coke briquette of the present invention is in the form of an elliptical sphere. In addition, in the present invention, steelmaking slag powder is added and mixed by:
Since coke powder is porous and its surfaces are welded groups of thin amorphous spheres, coke powder alone has a weak bonding force between particles, and compression molding requires a large amount of a binder with strong adhesive force. There is a drawback that it requires Therefore, crystalline steelmaking slag is added to surround the coke particle surfaces, entangle the crystalline particles, and perform compression molding to form a dense and strong briquette. Incidentally, the apparent specific gravity of coke briquette with steelmaking slag powder added is 1.26, but by adding steelmaking slag powder, the apparent specific gravity becomes 1.54, resulting in a heavy and strong briquette. In addition, during curing after forming, due to the influence of moisture in the briquette, lime is leached or crystallized from unsalted lime and calcium silicate in the steelmaking slag, and wustite is leached from the iron contained in the steelmaking slag. It has the advantage of having a self-hardening effect, such as penetrating into the fine pores of the particles and contributing to bonding between particles. In addition, in charging the converter, steelmaking slag is a product of the converter, so it is harmless in terms of components during converter refining, and as a briquette, the softening effect of steelmaking slag prevents rapid thermal decomposition, and the briquette This has the effect of increasing thermal efficiency by increasing the specific gravity of the ore and preventing floating flow within the furnace. Therefore, the relatively thin steelmaking slag used to increase the strength of the briquettes described above has a good ability to fill minute gaps, and small particles with a large surface coverage are also good for the self-hardening reaction during curing. As for the particle composition, the effect is remarkable when the proportion of 100 mesh or less in 100 parts by weight of steelmaking slag powder is 80 parts by weight or more. Also, the amount added should be enough to cover the coke surface and fill the particle voids during molding. Adding a large amount will unnecessarily increase the surface area of the particles, so it is necessary to add it to maintain strength immediately after molding. This can be a factor that hinders the effect of organic binders, so in the examples, 5 to 5 parts by weight of coke powder is used.
The objective could be achieved at additions in the range of 20 parts by weight. That is, if the amount of steelmaking slag added to the coke content is 20 parts by weight or more, the calorie content of the briquette decreases, and if it is less than 5 parts by weight, the binding strength becomes weak. The organic binder is added in an amount sufficient to compensate for the drawback that the above-mentioned steelmaking slag powder alone is strong against compressive fracture but brittle immediately after molding, and to withstand falling during handling after molding. Therefore, it is desirable that the binder be fast-acting, adhesive, and contain components that are harmless to converter refining. or molasses as the main ingredient (these are concentrated liquids with a solid content of usually 20 to 50 parts by weight per 100 parts by weight of an aqueous solution),
Alternatively, a polymer resin such as polyvinyl alcohol may be used. Since it is an organic substance, it has a calorific value and can contribute to the calorific value of the briquette. As mentioned above, the amount added may be an amount that can withstand handling immediately after molding, and will vary depending on the adhesive strength of the added substance. For example, in the example, by adding 4 parts by weight of an aqueous lignin solution (2 parts by weight in solid form) to 100 parts by weight of coke powder, satisfactory strength could be obtained immediately after molding. Considering the minimum value for destruction during transportation, economic efficiency, and caking properties, add 0.3 to 4 parts by weight of organic binder to 100 parts by weight of coke (0.15 to 2 parts by weight in terms of solids).
The range is fine. FIG. 2 shows the manufacturing process of another embodiment in which the entire amount of coke powder is molded. The briquette was then milled using a fret mill 22 until it became 80 parts by weight or more per 100 parts by weight of coke powder with particles of 3 mm or less in size, mixed with steelmaking slag, added with a binder, and molded. There is almost no difference. Therefore, coke powder may be sized by either classification or pulverization. The drop strength of the coke briquette produced by the method of the present invention immediately after forming was such that it could withstand a single drop from 1 to 2 m onto a steel plate,
When the steelmaking slag powder is stored at a depth of 500 mm and cured with natural ventilation indoors at a humidity of 50 to 70%, the self-hardening effect due to the reaction of the steelmaking slag powder with moisture and the effect of the organic binder will cause the
As shown in the figure, it became a strong briquette. Figure 4 shows a product of the coke briquette of the present invention, which is mixed with the composition shown in Table 1 No. 3 according to the process shown in Figure 1 and molded with a compression force of 1000 kg/cm ² in a continuous compression molding machine 13. FIG. 4 is a diagram showing the fall strength at each time point during aeration and curing in the product storage area 20 after being stored in a box 16. Drop strength is measured by placing 1 kg of coke briquette in a bag and repeatedly dropping it from a height of 10 m onto an iron plate three times, and then sieving through a 5 mm mesh sieve. The horizontal axis of Figure 4 shows the number of days elapsed after curing, and the vertical axis shows the 5mm
This shows the weight yield of the mesh, and as the number of curing days passes, the yield of 5 mm or more increases, and in 7 days it becomes a briquette that can withstand the use of a normal large converter. Therefore, it is thought that the reaction formation period of the steelmaking slag's self-hardening effect and the drying period due to reaction heat or ventilation are up to 7 days. Regarding the size of the briquette, if it becomes large, it will easily break due to the impact of falling due to its own weight, and it cannot be used for the purpose of raising the temperature in a short time in the converter. Burning is required in a short time of about 7 minutes, and if there is any unburned remains, there is a loss of energy, and if it is small, it will break during handling and become less than 5 mm and will easily scatter in the converter. , the length and thickness are preferably in the range of 10 to 50 mm. Also, since a spherical surface with no corners is strong against drop impact, it is best to use a regular oval charcoal-like shape. The shape of the coke briquette in the example is 35 mm in width and length.
It is charcoal-like with dimensions of 46 mm and thickness of 21 mm, and each ridge line and corner are spherical. (Example) Examples are shown in Table 1 below.

【table】

[Table] (Effects of the invention) As mentioned above, the coke briquette produced by the method of the present invention has almost the same effect as lump coke by adding steelmaking slag powder, which has been unused in the past. Therefore, it can contribute to thermal energy, improve steel manufacturing yield, or increase steel manufacturing production at low cost. However, it is extremely useful and in particular demand in recent new iron manufacturing methods.

[Brief explanation of drawings]

FIG. 1 is a manufacturing process diagram of the coke briquette of the present invention,
Figure 2 is another manufacturing process diagram of the present invention, Figure 3 is a diagram showing the particle size distribution, molding yield, and crushing strength of coke before compression molding, and Figure 4 is a diagram showing the falling strength during the curing process of the example. It is a diagram. 1; Receiving hopper, 2; Belt feeder,
3, 6, 13, 15, 17; belt conveyor,
4; Vibration conveyor, 5; Screened product box, 7; Sub-hopper, 8; Mixer, 9; Hopper, 10; Feeder, 11; Tank, 12; Quantifier, 13;
Roll compression molding machine, 14; Net conveyor, 1
6; Product box, 18; Hot air generator, 19; Exhaust fan, 20; Product storage area, 21; Dryer, 22; Fret mill, A; Particle size composition range of received coke powder, B; Particle size of coke powder after sizing configuration range,
C: Molding yield, D: Crushing strength.

Claims (1)

[Claims] 1. The particle size structure of strongly coking coal coke powder is 3 mm or less.
The particles are sized so that 80 parts by weight or more and the remaining 20 parts by weight or less exceed 10 to 3 mm, and then 5 to 20 parts by weight of steelmaking slag powder are added to 100 parts by weight of the sized coke powder, and an organic Add 0.15 to 2 parts by weight of a binder on a solid basis, adjust the water content to 6 to 12 parts by weight based on 100 parts of the dry weight of the mixture, and mix.The resulting mixture is continuously compression molded. A method for producing coke briquette for steelmaking furnaces, which comprises forming the coke briquette in a machine and aerating it.