JPH0772310B2 - Sintered ore manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a sintered ore of a metal oxide such as iron ore (chromium oxide, zinc oxide, manganese oxide, etc.).

(Prior Art) Japanese Patent Laid-Open No. 61-110729 discloses a method for producing a sintered ore in which a cross-sectional image of the sintered ore is obtained online using radiation tomography and the operating method is adjusted and controlled based on this. Proposed.

(Problems to be Solved by the Invention) It is well known that the pores of the sinter have a strong correlation with the quality of the sinter, but JP-A-61-110729 describes this in the process of producing the sinter. Generated pores (hereinafter also referred to as voids)
We found that the strength and yield of sintered ore deteriorated extremely when the pores exceeding 500 μm exceeded 20% of the total pore area, and we used the means to grasp these pores online and in real time. It is possible to improve the industriality of the sintering process by producing a sintered ore while controlling the temperature.

However, this finding is based on the finding that the strength and yield of sintered ore are extremely deteriorated when all of the pores exceeding 500 μm are targeted, and these pores exceed 20% of the total pores including other pores. It is based on it.

However, the present inventors have made
Even if the number of pores exceeding μm exceeds 20% of all pores, it constitutes more than +5 mm in equivalent circle diameter,
On the contrary, the pores of 0.5 to 5 mm gradually decrease, and the ideal strength and yield of the sintered ore are controlled in the region where the porosity exceeding 500 μm does not exceed 20%. From the practical point of view of fluctuations in conditions, we have found that a sinter of satisfactory quality cannot be obtained unless the porosity of +5 mm is controlled and controlled within a prescribed range.

(Means for Solving Problems) In order to solve the above problems, the present invention has the following means.

That is, when the radiation is applied to an arbitrary cross section of the sinter, the operation of scanning the cross section to detect the transmitted radiation intensity is performed from the periphery of the cross section, and the obtained transmitted radiation intensity is used to detect the transverse radiation. While synthesizing the image of the surface, the radiation intensity for each of the constituent pixels of the image is divided by the CT value defined below, and one size indicating a negative CT value within the division of the negative CT value exceeds 5 mm. Calculate the ratio of the part (hereinafter referred to as +5 mm pores), and if the ratio exceeds 40%, increase the mixing ratio of quick lime in the sintering raw material, decrease the mixing ratio of powder coke, or both. It is a method of manufacturing a sintered ore characterized by the above.

Definition of CT value μw: X-ray absorption coefficient of water μs: X-ray absorption coefficient of sample K: Constant (K = 1000 in the present invention) Example CT value of water = 0 CT value of air = −1000 In the present invention, the tube voltage is When dividing by CT value when irradiating as 420 KV, it is necessary to divide each of the part showing negative CT value and the part less than 2000 in the positive CT value into the above-mentioned pores or cavities. This is because the latter is in the unmelted state, where the sintering incomplete portion existing in the sintered portion outside the pores, that is, the solvent lime and serpentine does not melt and react. This is to detect the part.

Therefore, the adjustment and control of the sintering method performed at this time are carried out by taking action items as usual measures for improving the strength, such as increasing the proportion of quick lime, reducing the proportion of powdered coke, and reducing the proportion of easily meltable raw materials. This is because when there is an unsintered part, adjustment of the sintering method performed to eliminate this unsintered part, action items for control, later reduction of quick lime content, increase of coke powder mixture, and easy melting raw material Since the action is contrary to the increase of the mixture, the fact grasping by radiation tomography will be utilized to the maximum, and the decrease of the two in a delicate relationship will be eliminated promptly and accurately.

(Function) The above-mentioned findings obtained by the present inventors, that is, the fact that the influence of the pores (voids) on the strength and yield of the sinter is reversed when the equivalent circle diameter is 5 mm will be described below.

FIG. 1 shows the results of the investigation by the present inventors together with the proportion of the pores exceeding 500 μm.

As is clear from FIG. 1, the porosity exceeding 500 μm is 20
Increasing above 5% are pores of +5 mm and decreasing below 5 mm.

When the relationship between the porosity of +5 mm and the strength of the sintered ore was investigated, it was found that the strength becomes 50% or less when the porosity of +5 mm exceeds 40%, as shown in FIG.

As shown in Fig. 1, the actual state of increasing pores was +5 mm, and the relationship between the total porosity and the apparent voids (pores) remaining in the product after crushing the sintered ore was investigated. The relationship became clear.

This indicates that the apparent porosity remaining in the product after crushing is substantially controlled by the porosity of +5 mm.

The porosity of +5 mm is the I-type strength index (▲ II
⁴⁰ ₅ ▼: +5 mm% after 4 rotations), that is, the strength, as shown in FIG. 4, was found to begin to decrease significantly when the porosity exceeded 40%.

When this type I strength index (▲ II ⁴⁰ ₅ ▼) is compared with the conventional yield test value, it corresponds as shown in FIG. 5, and by improving the type I strength index (▲ II ⁴⁰ ₅ ▼) In addition, the yield and yield can be expected to be improved, and when these are combined, the strength and yield of the sintered ore are shown in Fig. 4 by controlling and controlling the sintering process so that the porosity of +5 mm does not exceed 40%. As shown in Fig. 4, when the strength was first improved, and then the vertical axis in Fig. 4 was replaced with the above findings in Fig. 5, the yield was also improved and the quality of the sinter was improved step by step. It was.

Since the present invention grasps the sintering condition of the sintered ore in a desired cross-section of the sintered ore online, it is possible to accurately grasp the actual condition of the sintered ore, and therefore the action requires appropriate items and quantities. It is possible to select, and it is easy to check the actual improvement of the sintering situation by that action, and it is possible to quickly adjust the appropriate action state by controlling over-action and insufficient action.

The CT part of the sintered pores shows a negative value regardless of whether the tube voltage is 420 KV or 150 KV, but the unsintered part shows less than 2000 in the former and less than 3000 in the latter. . In other words, the CT value varies depending on the tube voltage even for the same irradiation body. In this situation, the CT value at each tube voltage is shown with reference to the CT value 2000 at the tube voltage of 420 KV as shown in FIG. Therefore, in the present invention, the CT value is determined for each tube voltage based on the relationship shown in FIG.

(Example) Radiation cross-section imaging conditions Radiation: X-ray voltage: 150 KV Measurement location: Floor mat ore Measurement conditions: 1 piece / 2 minutes using a moving average value of 30 minutes Porosity: CT value, all negative values The ratio is calculated with the total area of pores larger than 5 mm as the numerator with the area as the denominator.

Unsintered part: CT value with the total area of sinter ore-total pore area as denominator
The ratio is calculated with the total area under 2000 as the numerator.

Implementation results (shown in FIGS. 6 (a) and 6 (b)) As is apparent from FIG. 6 (a), the occurrence status of pores exceeding 5 mm in the product sintered ore is 40 in A of the present invention. In contrast, the conventional example B, which does not use the radiation cross-section imaging method, greatly fluctuates in the range of more than 40%, while it is less than 40%. The actions performed by Example A of the present invention during this period were in the range of 0.4% to 2.0% for the mixing ratio of quick lime, and for the coke powder, all adjustments were completed in the range of ± 0.06%.

Further, as is clear from FIG. 6 (b), the yield status of the product sintered ore was 80% or more in all cases A of the present invention example, but 74% to 77% in the conventional example. There was a barracks situation in the lower range.

(Effects of the Invention) The present invention carries out a radiation cross-section imaging method online and realistically, and obtains the area ratio of all pores exceeding 5 mm in the total pore area obtained from this moment by moment, and when the ratio exceeds 40%. Since the operating conditions are adjusted and controlled to 40% or less, it has great industrial and industrial effects such as the efficient production of yielded and high-strength sinter.

[Brief description of drawings]

Fig. 1 is a diagram showing the total porosity and the composition of the pores exceeding 500 µm together with the ratio, Fig. 2 is a diagram showing the relationship between the porosity of +5 mm and the strength of the sinter, and Fig. 3 is the total porosity. Figure 4 shows the relationship between the apparent porosity (porosity) remaining in the product after crushing the sinter, and Fig. 4 shows the porosity of +5 mm and the type I strength index of the sinter (▲ II ⁴⁰ ₅ ▼: after 40 rotations). , +5 mm%),
Figure 5 Figure showing the comparison between the type I strength index (▲ II ⁴⁰ ₅ ▼) the conventional yield test values, FIG. 6 (b), a diagram showing a (b) Example a result, (i ) Is a diagram showing the occurrence of 5 mm pores, (b) is a diagram showing the yield of sintered products, and Fig. 7 is a diagram showing the relationship between the tube voltage of the radiation source and the CT value of the irradiated object.
The characteristic relation figure of the tube voltage and the CT value which the irradiation object of the X-ray which shows a CT value 2000 at 0 KV shows each tube voltage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsu Konishi Oita City, Oita City, 1-chome Nishinosu Nippon Steel Co., Ltd. Oita Steel Co., Ltd. Oita Steel Works, Ltd.

Claims (1)

[Claims] 1. When the radiation is applied to an arbitrary cross section of the sinter, the operation of scanning the cross section to detect the transmitted radiation intensity is performed from the periphery of the cross section, and the obtained transmitted radiation intensity is obtained. While synthesizing the image of the cross-section from, the radiation intensity for each of the constituent pixels of the image is divided by the CT value defined below, and one size indicating a negative CT value within the negative CT value division is
Calculating the ratio of the portion exceeding 5 mm, when the ratio exceeds 40%, increase the mixing ratio of quick lime in the crystal raw material, or reduce the powder coke mixing ratio, or both characterized by baking Manufacturing method of calculus. Definition of CT value μw: X-ray absorption coefficient of water μs: X-ray absorption coefficient of sample K: Constant (K = 1000 in the present invention) Example CT value of water = 0 CT value of air = −1000