JPH0153335B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing mini-briquettes by molding and granulating fine raw material powder among sintered raw materials for iron manufacturing. [Prior Art] Generally, sintered ore is used as a charging material for a steelmaking blast furnace, and in producing this sintered ore,
In order to improve the productivity of the blast furnace, the strength and reducibility of the sintered ore should be improved and the particle size of the sintered ore should be increased to approximately 5 to 50%.
It is required to size the particles to about mm. For this reason, the fine powder raw materials generated in the sintering process, raw materials, sinter transportation process, etc. should be sieved using an appropriate sieving means as much as possible, and then used repeatedly as sintering raw materials in the sintering process. It is. However, in general, as the blending ratio of fine powder raw materials (generally refers to raw materials with -0.125 mm particle size ratio of 30% or more) in the sintering raw materials increases, the productivity of sintered ore decreases and the production rate remains constant. It is known that if an attempt is made to maintain this, the product yield will decrease, sintering costs will increase, and cold strength will decrease. Therefore, when increasing the blending ratio of fine powder raw materials, some of the limestone powder in the sintering raw materials is replaced with quicklime or slaked lime, or the blending ratio of quicklime and slaked lime is increased to improve the air permeability of the mixed raw materials. It is common practice to force someone to do something. On the other hand, quicklime or slaked lime is expensive compared to limestone powder, resulting in a considerable increase in production costs, and the higher the proportion of fine powder raw materials, the smaller the effect of replacing or adding quicklime or slaked lime. In addition, as a processing method for these fine powder raw materials,
No. 49-15522 proposes a ``pretreatment method for sintering raw materials used in combination with flocculants and dispersants'';
In this method, a flocculant is added to the blended raw materials, a dispersant is used, and the materials are mixed in a mixer and then sintered. This method also has the disadvantage that the flocculant and dispersant are expensive, leading to an increase in the cost of producing sintered ore. Furthermore, in the "Pre-treatment method of fine powder sintering raw material" of Japanese Patent Publication No. 56-21314, mini-pellets (pellets with a particle size of 1 to 7 mm account for 75% or more) are produced in advance, and the mini-pellets are added to the sintering raw material. Methods of improving air permeability have also been proposed. This method is
When producing mini-pellets, a considerable amount of additives such as bentonite is required, and there is a possibility that the mini-pellets will be powdered during the sintering process.If they are powdered, their contribution to improving the productivity of sintered ore will be It becomes less. The above-mentioned method for processing fine powder raw materials requires expensive additives and equipment costs, and when added as a sintering raw material, it does not necessarily produce the desired addition effect due to pulverization, etc., and is not suitable as a sintering raw material. It is sufficient. [Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the conventional techniques as described above, and to process fine powders of various dusts, iron sand, and pellet feed used as sintering raw materials into fine briquettes (mini briquettes). ) and then adding it as a sintering raw material to reduce the blend of quicklime, improve the yield, and reduce the manufacturing cost of sintered ore. It's about doing. Furthermore, the mini-briquette manufacturing method according to the present invention is an effective means for dealing with the future expected pulverization of sintering raw materials. [Means for Solving the Problems] The mini briquette manufacturing method of the present invention is suitable for producing sintered raw materials mainly composed of iron ores, including -4 mm and -0.125 mm.
30% or more of single or mixed raw materials with a viscosity of 0.5
~20C.P such as alcohol waste liquid, quicklime, coal tar, carboxy methyl cellulose (CMC), corn starch, American flour (M powder),
Adding 1 to 3% by weight of one selected from polyvinyl, alcohol (PVA), propane deasphalt asphalt (PDA) waste oil, or a mixture thereof;
It is characterized by molding and granulating into mini briquettes of 1 to 5 mm ψ x 1 to 10 mm L using an extrusion molding machine, such as a horizontal die extrusion granulator. [Function] When fine powders such as iron sand, pellet feed, blast furnace dust, converter dust, and precipitated scale are formed into mini-briquettes by extrusion molding in this manner, alcohol waste liquid is used as a binder among the above additive solutions. At a blending ratio of 1.5 to 2.0% by weight (moisture 4.5% by weight), both the molding yield and strength of +1 mm are maximum,
+1mm molding yield can be expected to be 95%, thermal cracking,
Collapse due to secondary addition of water during the sintering process is extremely rare, and when the briquettes are dried at room temperature, the strength tends to gradually decrease, but when dried at 105℃, the strength rapidly decreases at a moisture content of 1 to 3%. decreases, but recovers as it approaches 0%. Furthermore, according to the sintering pot test using these mini briquettes, the mini briquettes tended to improve both production rate and yield compared to the case where fine powder raw materials were mixed, and when the tumbler strength was constant, the production This is an improvement of about 3% with a yield of about 8%. From the above results, in the mini briquette manufacturing method of the present invention, the extrusion molding machine used is not limited to the disk horizontal extrusion granulator, but it goes without saying that any extrusion molding machine can be used. The amount of the solution added is in the range of 1 to 3% by weight in view of its effects. The method of the present invention and the sintered mass of mini-briquettes formed by the method of the present invention will be described below with reference to Examples. [Example] Example 1 FIG. 1 is a process diagram of the mini briquette manufacturing method of the present invention. First, a mixture having a blending ratio shown in Table 1 was used as the ore fine particle mixed raw material in FIG.

[Table] Also, as an extrusion molding machine, a die horizontal extrusion granulator (Dice diameter: 174mm Roll diameter: 100mm
Capacity: 30Kg/H) was used. Furthermore, as a result of investigating the relationship between the viscosity and concentration at 20°C of various additive solutions added as binders, the results shown in Figure 2 were obtained. In Figure 2, A: Alcohol waste solution B: -0.5mm quicklime solution C:
Carboxy methyl cellulose (CMC) 2% solution for food additives D: Industrial CMC 2% solution (E): Cornstarch 4.5% solution (F) Meriken flour 5% (However,
(heated at 100℃ or less): 5% American flour (however, 0.5% NaOH is mixed and added to 5% American flour.
(heated below ℃): 5% polyvinyl alcohol
It shows the viscosity and concentration % at 20°C of solutions 1 to 1, respectively. Although each of these binder solutions is effective when used in the method of the present invention, the properties of the mini briquettes vary depending on the type and blending ratio of the binder. In order to reduce manufacturing costs, which is the objective of the present invention, an inexpensive binder is required. Therefore, in this example, relatively inexpensive alcohol waste liquid was used as a binder, and its addition ratio and briquette properties were determined. We investigated the relationship between (1) Moldability: Table 2 shows the results of examining the moldability using an extrusion molding machine while changing the alcohol waste liquid blending ratio and the moisture content during molding.

[Table] As shown in Table 2, as the blending ratio of alcohol waste liquid increases, the appropriate moisture content decreases. In Table 2, the drum strength and particle size of 8 cases of briquettes that could be granulated (marked with ◯) were investigated. (2) Drum strength: A drum strength test was conducted under the drum test conditions shown in Table 3, and the results are shown in FIG.

[Table] As shown in Figure 3, the drum strength tends to increase as the proportion of alcohol waste increases.
% combination reached the maximum. (3) Briquette particle size: Briquette yield (+1
mm) and particle disintegration due to thermal cracking and water addition, the particle sizes were examined immediately after molding, after the thermal cracking test, and after the added water test, and the results are shown in Figures 4-
The results shown in Figure 6 were obtained. As shown in the figure, similar to the drum strength, a peak is shown when 1.5 to 2.0 weight of alcohol waste liquid is added, and a yield of 90% or more can be expected. It was also shown that thermal cracking and particle collapse due to added water were extremely low. From the above results, it can be seen that mixing the alcohol waste liquid as a binder in a range of 1 to 3% by weight gives good results on moldability. (4) Changes in briquette strength over time: Changes in strength of briquettes during drying were conducted in two cases: room temperature drying and 105℃ drying. The results are shown in Figures 7 and 8, respectively.
I got the diagram. In Figures 7 and 8, () shows the case of 2% alcohol waste liquid () shows the case of 1% alcohol waste liquid, and in Fig. 7, the test time is 48 hours after molding, 4
Figure 8 shows the test time 6 hours after molding and 1 hour after molding.
This figure shows the relationship between the moisture content (%) in the briquette and the drum strength (DI+1 mm) over time. As shown in the figure, in the case of the room temperature shown in Fig. 7, the drum strength shows a tendency to gradually decrease as it dries.
On the other hand, in the case of Fig. 8 where the material is dried at 105°C, the strength decreases rapidly, but once the minimum value is exceeded, the strength recovers. The reason for this is not clear, but in the case of forced drying, it is thought that a moisture difference occurs in the radial direction of the briquette, and this is expected to affect the strength. Example 2 Next, in order to confirm the effect on the sinterability of mini briquettes, a sintering test was conducted in a sintering pot (300 mmφ x 480 mm height) under the following conditions. (1) Test method

【table】

[Table] In order to eliminate the influence of moisture in the briquettes,
The briquettes were previously dried to a moisture content of 0 to 0.5% before use. (2) Briquette particle size Figure 9 shows the particle size distribution of the dried briquettes used in this pot test. The 〇● marks in the figure are briquettes with 1% alcohol waste added (average particle size 3.09 mm) △
▲ indicates 2% alcohol waste liquid added briquettes (average particle diameter 3.19 mm) □■ indicates briquette raw material (average particle diameter 0.25 mm), and 〇△□ respectively indicate cumulative particle size (%). From Figure 9, alcohol waste liquid 1 has a particle size of 1 to 5 mm.
% combination is 85.7%, 2% combination is 87.6%, 2%
The additive formulation shows a slightly larger value. (3) Pot sintering test results (i) Pseudo particle size: Harmonic average of pseudo (half-dried) particles of test levels A, B, C, and D (circle indicates case D'). The arithmetic mean particle size is shown in FIGS. 10 and 11, and the particle size distribution after drying is shown in FIG. 12. As shown in the figure, the particle size of test levels C and D cases is larger than that of case A, and it seems that the briquettes are less likely to disintegrate during mixing with a mixer. Furthermore, the particle size distribution tends to decrease by 0.25 mm or less and increase by 3 to 5 mm due to briquette mixing (cases C and D). (ii) Productivity (a) Figures 13 to 16 show the pot test results, that is, the production rate (T/H・m ² ) at each level.
Sintering time and product yield (%) TI ₊₁₀ mm are shown.
As shown in the figure, test level case B had a long sintering time and the lowest production rate. On the other hand, mini briquettes (contains 2% alcohol waste liquid)
Case D, in which the sintering time was approximately the same as Case A, showed a high product yield and the highest production rate. (b) Product yield and tumbler strength are plotted as a function of sintering time in Figures 17 and 18. As shown in the figure, when compared at the same time, the case in which mini briquettes were mixed
CD tends to improve both yield and strength compared to case AB. (c) Also, the tumbler strength is constant (42.8% constant)
When the production rate, product yield, and sintering time are corrected and illustrated, the results are as shown in FIGS. 19 to 21. As shown in the figure, Case D, which is blended as mini briquettes, has a production rate of about 8% higher than Case B, which is blended as fine powder.
It is clear that the yield has improved by 3%. Furthermore, when Cases C and D are compared, Case D is better, showing the difference in the binder (alcohol waste liquid) addition rate. (iii) Quality of the sintered ore obtained in Figures 22 to 24
RDI, RI and FeO (%) are shown. Although the data varies widely, there are no noticeable differences in each case, and it seems that the effect of converting fine powder into mini-briquettes is small. Example 3 Next, as a result of investigating the drum strength and thermal cracking of mini briquettes to which quicklime and a solution consisting of a combination mainly composed of quicklime was added as a binder, the particle size distribution of each after water addition, the briquette product yield, and the binder viscosity, The results shown in Figure 25, Figure 26, and Table 4 were obtained. As shown in the figure, each index changes depending on the combination of binders, but thermal cracking in each binder and particle collapse due to added water are small, and if the strength is within this range, it is thought that powdering will be small even if added as a sintering raw material. Table 4 shows the results of measuring the viscosity of the binder used in this test. The binder viscosity of A to D is
It is in the range of 3.5 cp. Further, since the viscosity of the alcohol waste liquid in the 8 cases in Example 1 was 0.5 cp to 5 cp, it is understood that a binder viscosity in the range of 0.5 cp to 20 cp gives good results for moldability.

〔Effect of the invention〕

The mini-briquette produced by the method of the present invention can be used as a sintering raw material, and can reduce the amount of quicklime added and improve the yield of sintered ore. This is extremely useful as it reduces manufacturing costs and raw material costs due to the price difference between conventional sintered raw materials and pellet feed.

[Brief explanation of drawings]

Figure 1 is a process diagram of the method of the present invention, Figure 2 is a graph of the relationship between the viscosity and concentration of various binders, Figure 3 is a graph of the relationship between alcohol waste liquid blending ratio and DI ₊₁ mm,
Figures 4 to 6 are relationship graphs of alcohol waste liquid blending ratio and particle size immediately after molding, after heat cracking test, and after added water test, respectively. Figures 7 and 8 are graphs of briquette drying at room temperature and 105℃ drying. Fig. 9 is a particle size distribution diagram of the briquettes used in the pot test, Figs. 10 and 11 are graphs showing the harmonic mean and arithmetic mean particle size of pseudo particles, Fig. 12
The figure is a particle size distribution diagram after drying, Figures 13 to 16 are graphs showing the production rate, sintering time, product yield, and TI ₊₁₀ mm at each level of the pot test, and Figures 17 and 1
Figure 8 is a graph showing the relationship between sintering time and product yield and TI ₊₁₀ mm, respectively. Figures 19 to 21 are graphs showing the relationship between sintering time, product yield, and TI ₊₁₀ mm, respectively. Figures 19 to 21 show the relationship between production rate, product yield, and sintering time when TI +10 is constant. The correction diagrams, Figures 22 to 24 are graphs showing the RDI, RI and FeO% of the sinter obtained in Example 2, and Figures 25 and 26 are graphs showing the DI of various binders in Example 3. Graphs showing _{the +1} mm particle size and the briquette product yield immediately after molding, after the heat cracking test, and after the water addition test. Figures 27 to 30 are the production rate, sintering time, and product yield in Example 4, respectively. 31 and 32 are graphs showing sintering time, product yield, and _{TI +10} mm, respectively.
It is a correction graph showing the relationship between

Claims (1)

[Claims] 1 Among the sintering raw materials mainly composed of iron ores, -4
mm and -0.125 mm 30% or more of single or mixed raw materials, and the viscosity of the solution containing raw material water is 0.5 to 20 C.P.
A method for producing mini briquettes, which comprises adding 1 to 3% by weight of a binder, and molding and granulating mini briquettes of 1 to 5 mmφ x 1 to 10 mm L by extrusion molding. 2 The additive solution contains alcoholic waste liquid containing water in the raw materials, quicklime, coal tar, carboxylic acid, etc.
A patent claim characterized in that it is one selected from methylcellulose (CMC), corn starch, American flour (M powder), polyvinyl alcohol (PVA), and propane deasphalt asphalt (PDA), or a combination thereof. A method for producing mini briquettes according to scope 1.