JPH0136537B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an improvement in pretreatment in the process of producing sintered ore by granulating a sintered raw material. [Prior art and its problems] Sintered ore, which is a raw material for a blast furnace, is obtained by pre-processing fine ore, and FIG. 1 shows a general method of processing it. First, each brand of fine ore unloaded from Vessel 1.
Stack f ₁ to f _o in rough ore yard 2. Next, these fine ore f ₁ to _{f o} are buried in a layered manner in the blending yard 3, and mixed in a preset ratio by a bedding method to form blending powder (hereinafter referred to as B powder). Next, the B powder is charged into separate mixing tanks 4 together with each raw material such as limestone, coke powder, and return ore. A predetermined amount of each raw material is continuously cut out from each blending tank 4 and blended, sent to a primary mixer 5 for water addition and granulation, and further granulated by a secondary mixer 6 as required. Raw materials granulated in this way (hereinafter referred to as pseudo particles)
is continuously charged from the hopper 7 to the pallet 9 of the sintering machine 8, and the coke powder mixed in the raw material is ignited using the ignition furnace 10. Force suction ventilation. Sintered ore is obtained by this method. However, with such a general method for producing sintered ore, productivity is low, it is not possible to reduce costs, and it is difficult to cope with an increase in the amount of sintered ore used. Many proposals have been made to solve this problem. For example, a widely known method is to add a granulation accelerator such as quicklime or slaked lime to raw materials to obtain pseudo particles with excellent air permeability. However, quicklime and slaked lime are more expensive than limestone, which is usually used as a CaO source, and have the disadvantage of increasing production costs. In order to alleviate this drawback, a method has been proposed in which the effect of quicklime is improved by heating the water added during granulation (Japanese Patent Publication No. 38494/1983). However, since this method also uses quicklime, it cannot avoid the drawback of high production costs. As another method, a method has been proposed in which water is added to the powder raw material to be sintered in advance, the mixture is charged into a mixing tank, and the powder is granulated using a primary mixer (Japanese Patent Publication No. 59-33646). issue). In this method, water is sufficiently permeated into powder B before granulation is performed, so the water effectively acts as a binder and the air permeability of the raw material can be increased. This has also been confirmed in experiments conducted by the present inventors. However, in this method, 70 to 100% of the maximum permeability moisture is added to all brands of fine ore, so the amount of water added is quite large. Furthermore, in this method, if the brand of fine ore is changed, the maximum air permeability moisture value changes, so it is necessary to measure this value again and change the amount of added moisture based on this measured value. For this reason, when changing brands frequently, there is a problem in that managing the amount of added water becomes complicated. Another proposal is to obtain pseudo particles with excellent air permeability by adjusting the particle size structure of the raw material within a predetermined range (Japanese Patent Publication No. 45738/1983). This method is
It would be good if the powder ore could be selected arbitrarily, but currently it is possible to mix only the powder ore that is piled up, so it is necessary to grind some of the powder ore and adjust it to a predetermined range. As a result, there is a drawback that the grinding cost increases and the manufacturing cost increases. Other methods have been proposed, such as focusing on the characteristics of fine ore brands, and dividing and blending highly wettable raw materials into the primary and secondary mixers, or blending only in the secondary mixer. (Special Publication No. 59-31575). This method uses a binder such as quicklime preferentially for raw materials with poor wettability, that is, raw materials with a small specific surface area, to improve pseudo-granulation properties, that is, granulation properties, or wet strength of pseudo-particles, and then sintering. This is a method to stabilize machine productivity and quality. However, according to the research results of the present inventors, the productivity of the sintering machine is affected not only by the pseudo-granulation property and the wet strength of the pseudo-particles, but also by the strength after drying. Moreover, the strength after drying strongly depends on the adhesion force, which is affected not only by the surface shape of various fine ore brands corresponding to the specific surface area determined by the BET method, but also by the particle shape, surface physical properties, etc. For these reasons, this method cannot be said to be a method that can fully achieve its purpose, and the present situation is that it has not yet been put into practical use. Another method proposed is to granulate the mixed raw material whose particle size has been adjusted using a pan pelletizer to improve the packing density of pseudo particles and obtain pseudo particles with excellent air permeability ( Special Public Service 1984-
32531-32533). Although this method is effective, it requires crushing or pre-granulation in advance to maximize the capacity of the granulator.
An increase in equipment costs is unavoidable. Moreover, according to the experimental results of the present inventors, what contributes to the productivity of the sintering machine is a powder ore brand that has weak strength after drying of the pseudo particles and also contains fine powder that acts as an adhering powder, that is, a certain specific brand. Therefore, even if all or some of the raw materials are granulated using a pan pelletizer after all the raw materials are mixed, it is not efficient. As a result, this method has the drawback of increasing equipment costs. Another method is the preliminary granulation method of fine powder raw materials that has been tested in the past (for example,
−1801, etc.). This method is an efficient and effective method when all of the fine powder raw materials are composed of fine ore brands whose pseudo particles have low strength after drying. However, the productivity of the sintering machine depends on the strength of the pseudo-particles after drying, and some fine powder raw materials include fine ore brands whose pseudo-particles have high strength after drying, so these things must be taken into account. This means that this method is inefficient and therefore requires high equipment costs. Therefore, this method is only implemented in a small number of cases. [Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and its purpose is to improve the strength of pseudo particles after drying, and to produce a sintering machine at a low cost. The present invention aims to provide a method for processing sintered ore that can improve its properties. [Structure of the Invention] In order to achieve this object, the present invention classifies various fine ore brands into a plurality of groups according to the dry strength and particle size of pseudo particles obtained by granulation, and divides the ore groups into groups. After blending each group, and then granulating each group of fine ore, the brand group with low strength and fine grain size after drying is granulated, and the brand group with high strength and fine grain size after drying is granulated. and granulate them together, and then the granules of the famous brand group are mixed and sintered. [Detailed Description of the Invention] When a binder such as slaked lime or quicklime is added to the sintering raw material, the productivity of the sintering machine is improved, although the manufacturing cost increases as described above. There are many reports on the reason for this, but to summarize these reports, the general consensus is that ``pseudo-particles during sintering go through processes such as wetting and drying, so the pseudo-particles collapse during drying. However, binders such as slaked lime and quicklime have the function of suppressing this disintegration phenomenon, that is, the function of improving the strength of the pseudo particles after drying.'' Considering that binders such as slaked lime and quicklime are expensive, the present inventors have developed a method for effectively blending binders such as slaked lime and quicklime with the aim of reducing the amount of binders such as slaked lime and quicklime. We considered this. First, we investigated whether the strength of the pseudo particles after drying depends on the brand of fine ore, and if so, the reason. In other words, various types of fine ore are granulated using a small granulator, while keeping the space factor, rotation speed, and granulation time constant, and adding an appropriate amount of moisture to the fine ore brand, and after granulation, the raw material is (pseudo particles) are dried under specified conditions, and then a certain force equivalent to the weight of the raw material on the sintering machine is applied. Powder ratio (expressed as the ratio of generated powder to blended powder)
was measured and evaluated. As a result, as shown in Table 1 below, it was found that the strength of the pseudo particles after drying was strongly dependent on the brand of fine ore.

[Experiment example]

Each of the various brands of powdered ores (A to E) shown in Table 1 was blended in an amount of 20% by weight, and this was used as a basic blend. In this table, A brand and B brand are fine ore brands with low strength of pseudo particles after drying and a lot of fine particles of 0.5 mm or less, and E brand is powder ore brands with high strength of pseudo particles after drying and with a lot of fine particles of 0.5 mm or less. It is a fine ore brand with a lot of fine powder. Using this basic composition, the mixture was mixed and granulated in the following manner. No. 1: A general method in which all raw materials are mixed and granulated in the same way. No. 2 to No. 4: The strength of the pseudo particles after drying is weak and
Pre-granulate A brand and/or B brand that has a lot of fine powder of 0.5 mm or less, and then granulate the granulated product together with E brand, which has strong strength and has a lot of fine powder of 0.5 mm or less, after drying the pseudo particles. , and then mixed with the remaining powdered ore granules (the present invention) No. 5: Contrary to Nos. 2 to 4, the strength of the pseudo particles after drying is strong and there are many fine particles of 0.5 mm or more in E. The brand is pre-granulated, and after the pseudo particles are dried, it is granulated together with the fine ore brand group consisting of brands A and B, which have low strength and many fine particles of 0.5 mm or less, and then the remaining fine ore is granulated. When mixed with substances (comparative method) No. 6, No. 7: The strength of the pseudo particles after drying is weak and
When a binder such as slaked lime or quicklime is added only to fine ore brands A and B, which contain many fine particles of 0.5 mm or less, and then granulated using a normal drum-type granulator (comparative method). Then, a pot test was conducted using each of the raw materials after granulation, and the sintering time (minutes) was measured. Table 2 shows the measurement results and the ratio of sintering time to the No. 1 method.

〔Effect of the invention〕

As is clear from the above results, according to the present invention, the brand group of quasi-particles with low strength after drying and a large amount of fine powder is used as the core particle, and the powder ore brand group with high strength after drying and fine particle size is used as the attached powder. By acting, the strength of the pseudo particles after drying can be improved without adding a binder such as slaked lime or quicklime, so productivity can be improved without increasing manufacturing costs.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a conventional sintering raw material processing method, Figure 2 is a characteristic diagram showing the effect of slaked lime and quicklime on the strength improvement after drying of pseudo particles, and Figure 3
Figures A and B are explanatory characteristic diagrams showing the results of granulation tests using mixed brands, Figure 4 is an explanatory characteristic diagram showing the apparent adhesion force of various powder ore brands and the strength after drying of pseudo particles, and Figure 5 is an explanatory diagram of characteristics showing the results of granulation tests using mixed brands. It is an explanatory view showing an example of the processing method of the sintering raw material concerning the invention. 1...Ship, 2...Rough ore yard, 3, 3a, 3
b, 3c...blending yard, 4, 4a,
4b...Blending tank, 5, 5a, 5b...Primary mixer, 6...Secondary mixer, 7...Hopper, 8...
Sintering machine, 9...Pallet, 10...Ignition furnace, 11
...Wind box, 21...Preliminary granulator.

Claims (1)

[Claims] 1. Classify various fine ore brands into multiple groups according to the dried strength of the pseudo particles obtained by granulation and the particle size of the brand, blend each ore group, and then blend the fine ore from each group. When granulating, after drying, a brand group with low strength and fine grain size is granulated to form core particles, and then this is charged into a granulator together with a brand group with high strength and fine grain size after drying. After drying, brand groups with strong strength and fine particle size are granulated together by acting as adhesion powder, and then the granules of each brand group are mixed and sintered.