JPS5938307A - Method for blending lump iron ore for blast furnace - Google Patents

Abstract

PURPOSE:To reduce the fuel ratio of a blast furnace and to stabilize the operation of the furnace by regulating the percentages of lump iron ores to be blended in accordance with a characteritic value of each of the ores estimated from the porosity. CONSTITUTION:Only the porosity of each of iron ores is measured to estimate one or more characteristic values of the ore such as the JIS reduction index RI, reduction powdering index RDI and tumbler strength TI. The physical properties (RI, RDI and TI) of a blended ore are estimated in accordance with the estimated characteristic values, and the percentages of the iron ores to be blended are regulated so as to provide the desired physical properties.

Description

[Detailed description of the invention] The JIS reduction rate (RI), reduction ratio (RDI) and tumbler strength (TI) of blast furnace iron ore are easily estimated, and the quality as blending ore is determined by the estimated values. By controlling this, the gas utilization rate and air permeability in the blast furnace are improved, the blast furnace fuel ratio is lowered, and the blast furnace operation is stabilized.

Recent advances in ironmaking technology, such as advances in ore pre-treatment technology and combined air blowing technology, as well as dramatic advances in the size and pressure of blast furnaces, have led to a significant increase in the pig iron production ratio and a sharp decline in the fuel ratio. There is. By the way, the stable operation of large blast furnaces today is said to be due to advances in ore processing technology, and for this reason, ironmaking engineers are working hard to improve and stabilize the quality of sintered ore and pellets for charging into blast furnaces. Efforts have been made to improve the quality of iron ore, but even though efforts have been focused mainly on sizing and strengthening blending, in actual blending management, it is difficult to Physical properties of single ore or blended ore (RISRDI, T
I) is left unchecked, depending on ship allocation or supply and demand, and it must be said that it has changed considerably.

In other words, it is unavoidable that the physical properties (RISRDI, TI) of a single brand of ore vary depending on the arrival of the ship, and measuring this individually for each arrival requires too much labor and expense. Regarding the actual measurement of each physical property as mentioned above, it is considered to be quite difficult to apply it to blend management in actual operations due to the difficulty of collecting representative samples and the extremely large dispersion of the actual measured values. As mentioned in 5 above, the situation is such that it has no choice but to be left unchecked. However, in blast furnace operation, it is always a question of how to stably supply pig iron with high productivity and a low fuel ratio. Many proposals have been made on how to improve gas utilization by ensuring air permeability in the blast furnace from the raw material properties of ore and pellets. It is well known in the field that, because there is no preferred method for controlling the various physical properties mentioned above, in actual blast furnace operation, situations sometimes occur with unknown causes. be.

The present invention was developed after repeated studies in view of the above-mentioned circumstances, and by measuring only the porosity of iron ore alone, the RI (JIS reduction rate) and RDI of each iron ore can be measured.
(M source powdering rate) and TI (tumbler strength) are estimated, and the physical properties (RISRDISTI) of the blending ore are also predicted to achieve the predetermined target physical properties, that is, RI≧50%.
, it is proposed to change the brand of iron ore used or adjust its blending ratio so that RDI≦20% and 480%. That is, to further explain the present invention, the present inventors have determined the physical properties (RI, R
Considering the disadvantages of measuring DI, TI), we investigated various methods to easily and accurately determine these values, and as a result of practical examination, we found that the total porosity of ore [1-(
Apparent specific gravity/true specific gravity)] As summarized in Figure 1, for RI, γm=Q, 9Q,
Regarding RDI, γ"=Q, 86, and regarding TI, ℃ is also γ"
=Q, 85, which can be highly estimated and evaluated. In other words, the physical properties of single ore are most influenced by the total porosity rather than the surface structure, amount of gangue minerals, endowment status, etc., so the physical properties of most brands can be estimated only by the total porosity. Moreover, the porosity of such ores can be measured by a simple method such as charging the ore into mercury. In addition, whether the physical properties of the blended ore can be estimated from the physical properties of the single brand ore obtained as described above and its blending ratio can be determined by comparing the actual measured values and the estimated value from the single brand ore (by percentage). The results of the comparison and inspection of the values (1) are summarized as shown in Figure 2, and it was confirmed that they matched fairly accurately and that the additive force 3 was established.

Furthermore, the properties of the sintered ore and its blending ratio are approximately constant (70 to 80
As a result of a detailed study on how the blast furnace operation changes when the brand of blending ore, that is, the physical properties (RI, RDISTI) changes under the conditions of (I) ( It was confirmed that there is a considerable correlation as shown in (m).

(1) RI When we investigated the estimated RI and waste utilization rate of blending ore by selecting a period when the R1 of sintered ore was almost constant, we found that although there was considerable variation as shown in Figure 3, the RI of blending ore was Along with this improvement, the gas utilization rate is gradually improving. However, when RI = 1 inch or more, it remains flat and no clear trend can be seen.

(II) RDI Similarly, we selected a period when the RDI of the furnace and condensation was almost constant, changed the brand of ore used, and conducted a thorough investigation of the estimated average RDI and shaft pressure loss of the ore used, as shown in Figure 4. As shown in Fig. 1, it is not so obvious when the RDI of the ore is 20% or above, but when it is 20% or more, the shaft pressure loss gradually increases and the air permeability in the shaft tends to deteriorate.

@) TI Similarly, when the TI of sintered ore was l'j, lτ, the brand of ore used was changed, and the estimated average TI and η, (ventilation d) of the ore used were investigated. , as shown in Fig. 5, there is a considerable amount of Para28
%p has been gradually revised with the I's Commerce and Industry.

However, when H=so% or higher, no clear tendency was observed.

In other words, what are the properties of the sintered ore? 1. Under certain conditions, in order to improve the gas utilization rate in the blast furnace, the shaft pressure drop, and the permeability in the furnace, the average RI of the blending ore or the ore used must be 50 inches or more, average RDI of 2
It is important to control the average TI to 0% or less and 80% or more. That is, in the present invention, in consideration of these relationships, the average physical properties of the blending ore or the iron ore used are determined such that the average RI≧50%, the average RDI≦20%, and the average TI≧80%. The purpose is to change the brand or adjust the blending ratio. In other words, with the conventional technology, as mentioned above, the physical properties of iron ore are left unchecked, depending on ship allocation and supply and demand, and thus change considerably, making it impossible to control the physical properties. , in the present invention, the physical properties (RI, RDI, TI
) and use it to estimate the physical properties (RI, RDI, TI) of the blending ore or the iron ore used, and change the brand or its blending ratio l! By controlling the average physical properties, the gas utilization rate and air permeability in the blast furnace are improved, and the blast furnace fuel ratio is lowered and the blast furnace operation is stabilized.

Specific examples according to the present invention will be described below.

Example H, (RI sub-control case) Typical examples in the field name of normal operation are shown in Table 1 below. is the average RI of Frendenink° ore.
; high at 54.9%, and in case 3 it was also 51.
．． The average RI is 7%, which is somewhat high, but on the other hand, in Case 12, where there are many ores B and C with poor reducibility, the average RI is as low as 44.3 LIJ and fluctuates widely.

Table 1 Therefore, in such a case, according to the present invention, RI is estimated from the porosity of the ore, and the average R of the blended ore is calculated.
When I was predicted and the mixture was controlled to 50% or more as shown in Table 2 below for each case, the gas utilization rate ηeo in the blast furnace was 50.4%, 5Q, 8
%, 6G, and 1%, making it possible to appropriately reduce the fuel ratio and achieve stable operation.

Table 2 Example 2 (RDI control case) In case 2, in which ores B and C, which have good reduction and powderability, are often blended in normal operation, the average RDI of the blended ore is as shown in Table 3 below. The temperature is extremely low at 12.2%, and the shaft pressure loss is low at α22, but on the contrary, in case 1, where ores A and D, which have poor reduction and powdering properties, are mixed, the average RDI of the blended ore is 24.4%. It is quite high, and the shaft pressure loss is also high at Q, 31, and the fluctuations between them are extremely large.

Part 3 Obviously, in such a case, the example in which the average RDI of the blended ore is predicted by estimating the RDI from the porosity of the ore according to the present invention and is controlled to be 20% or less is as described in Part 3 above. The following Table 4 corresponds to cases 1 to 3 in the table, and by controlling in this way, the pressure loss in the blast furnace shaft can be reduced by α28 and α24.
Alternatively, it was possible to stabilize the TI at an extremely low level, thereby improving the ventilation inside the blast furnace and stabilizing the gas flow to achieve favorable operation.Table 4 Example 3 (TI (When controlled) In normal operation, if there is a large proportion of ore A1B with good room temperature strength, the average TI of the blended ore will be 85. The air permeability of the blast furnace (■24, p) is as high as 3.47 or &46. Ore with low strength at room temperature compared to koi
In the case of a sample containing a large amount of E, the average TI of prendink ore is 76.1% or 1. The blast furnace air permeability (V/4p) is as low as υ8, and the range of variation between them is large.

Table 5 Therefore, based on these cases, according to Kinoe Yu 1 (・Estimating TI from the porosity of the ore, predicting the average TI of the blended ore, and blending to control this to 80% or more. The improvement examples shown in Table 6 below are those in which the air permeability inside the blast furnace (V,
@ p ) can be stabilized at a high level such as 3.42, λ45 or &40, and it also stabilizes the gas flow in the blast furnace and reduces the blast furnace fuel ratio, allowing the blast furnace to operate in a luxurious and stable manner. I was able to figure it out.

Table 6 In accordance with the present invention as explained above, it is possible to elucidate the technical reality of blending iron ore for blast furnaces, and to adjust R1, RDI and TI appropriately by simply measuring the porosity of the iron ore. By estimating and controlling the quality of blending ore, it is possible to effectively improve the gas utilization rate and permeability in the blast furnace, thereby appropriately reducing the blast furnace fuel ratio and stabilizing the blast furnace operation. This invention has great industrial effects.

[Brief explanation of the drawing]

The drawings show the technical content of the present invention, and Figure 1 is a chart showing the relationship between the physical properties of ore and the porosity σ).
-) shows the relationship with RI, (b) with RDI, and (c) with TI, respectively. Figure 2 shows the relationship between actual measured values and subtracted values from single brand ore regarding the physical properties of blended ore. In the diagram, (,) is RI, (b) is RDI, (c)
shows the relationship between TI and the third
The figure is a chart showing the relationship between the average RI of iron ore and the gas utilization rate, the 4th M is a chart showing the relationship between the average RDI of iron ore and the shaft pressure loss, and the fifth figure is the chart showing the relationship between the average RI of iron ore and the shaft pressure drop. It is a chart showing the relationship between air permeability and air permeability. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Hori 1) Yutaka Iruma
Yamaoka Gyō Tsutsui Bema Tsutsumi − Daido
Ell Nakakuni
Department Kitajima - Tsuguday
/ EntsujiyLtemJ#''(%)7-TI<g Rumor 4) No. ,, TIXI R,1, (Kanemo) No. 41 Ship No. 6 l TL Brass)

Claims (1)

[Claims] 1. Porosity and RI by type and brand of lump iron ore. Find the correlation with physical properties such as RDI and TI, estimate one or more of the characteristic values such as RI, RDI, and TI from the porosity of the lump iron ore, and A method for blending lump iron ore for blast furnaces, characterized by adjusting a blending ratio of blending ore based on an estimated value. 2. The method for blending lump iron ore for blast furnaces according to claim 1, wherein the loaded average value of RI is adjusted to 50% or more. a. The method for blending lump iron ore for blast furnaces according to claim 1, wherein the loaded average value of RDI is adjusted to 20% or less. 4 Set the TI load average value to 80% or more and adjust the temperature by °C.'1-
A method for blending lump iron ore for blast furnaces according to claim 1.