JP2935611B2 - Manufacturing method of ferroalloys in electric furnaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ferroalloys in an electric furnace, and more particularly, to starting melting of raw ores in advance when melting or reducing raw ores by an electric furnace to produce ferroalloys. The present invention relates to a method for producing ferroalloys in an electric furnace for examining a temperature and a melting temperature range, using the raw material ore having the proper temperature as a molten raw material ore, and stabilizing operability.

[0002]

2. Description of the Related Art In the manufacture of ferroalloys in an electric furnace, raw ores and coke such as lump ore, sintered ore, and pellets are put into an electric furnace, and then heated by resistance heating between electrodes to melt the raw ore. Then, it is carried out by a method of obtaining alloyed iron by reduction with coke. The melted and reduced product is in a molten state, injected into a mold, and cooled to become a solid ferromagnetic iron.

[0003] At this time, the lump ore is usually put into an electric furnace in a state without any treatment such as sintering, that is, in a raw ore state. However, when the lump ore has a high moisture content, it may be dried with a drying device such as a rotary kiln before charging it into the electric furnace in order to reduce it or to increase the amount of heat brought into the electric furnace. is there. However, there is no prior evaluation of lump ore and improvement of lump ore for the purpose of stable operation of electric furnaces and improvement of each basic unit.
This is considered to be because those evaluation methods and modification methods have not been developed yet.

[0004]

In the conventional method for producing ferromagnetic iron in an electric furnace, as described above, prior evaluation of lump ore for the purpose of stable operation of the electric furnace and improvement of each basic unit, Since the lump ore is not modified, the operation of the electric furnace becomes unstable or the various basic units deteriorate, depending on the raw ore (raw ore of lump ore, lump ore dried for drying). There is a problem. That is, since the properties such as the melting temperature width of a part or most of the raw ore are unknown, the softening cohesive zone is widened depending on the raw ore, and therefore, the electric resistance value of the raw material in the electric furnace is reduced, and the electrode is Phenomena such as floating and difficulty in applying an electric load may occur, and the operation of the electric furnace may become unstable, or various basic units may be deteriorated.

For example, a manganese sintered ore used as a main raw material ore usually has a melting start temperature of 1350 ° C. or more,
The melting temperature range is within 200 ° C. On the other hand, the manganese lump ore A has a wide melting temperature range and the melting temperature range is shifted to the low temperature side. When a mixture of A is used (mixed), the softened cohesive zone is widened. Therefore, the electric resistance value of the raw material in the electric furnace becomes low, the electrodes float, the electric load is hardly applied, and the operation of the electric furnace becomes unstable. As a countermeasure, it is necessary to reduce the blending amount of the manganese lump ore A, and it is sufficient to do so. However, since the amount of the ore is limited, there is a problem in the supply and demand policy of the ore.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and an object of the present invention is to provide a ferroalloy in an electric furnace capable of stabilizing operability and improving each basic unit. It is to provide a manufacturing method of.

[0007]

Means for Solving the Problems In order to achieve the above object, a method for producing ferromagnetic iron in an electric furnace according to the present invention has the following configuration. That is, in the method according to claim 1, when the raw material ore is melted and reduced by an electric furnace to produce ferroalloys, the raw material ore is melted by measuring a melting start temperature and a burn-through end temperature by a high temperature load test in advance. Starting temperature is 1300 ~ 1500 ℃ and melting temperature range is 200
A method for producing ferroalloys in an electric furnace, comprising selecting a raw material ore within a temperature of ° C. and melting the raw material ore in an amount of 85% or more based on the total amount of the molten raw material ore.

[0008] The method according to claim 2 is characterized in that the melting start temperature is 13
Raw material ore that does not satisfy the condition of 00 to 1500 ° C and melting temperature range: 200 ° C or less is adjusted to a raw material ore that satisfies the condition by heating alone or mixed with other ores to the melting temperature or higher. 2. The method for producing ferromagnetic iron in an electric furnace according to claim 1, wherein the iron ore is used as a raw material ore containing 85% or more.

[0009]

The present inventor conducted various experiments and examinations on a preliminary evaluation method and a reforming method of raw ore for the purpose of stable operation of the electric furnace and improvement of each basic unit. As a result, the raw ore was subjected to a high temperature load test. It has been found that the melting start temperature and the burn-through end temperature can be measured. That is, by heating the raw ore under a constant load, and measuring the relationship between the temperature and pressure loss, the melting start temperature and the burn-through end temperature of the raw ore can be obtained relatively accurately, Therefore, it has been found that the melting temperature range can be determined. Further, the present inventors have found that a raw material ore can be suitably reformed by heating alone or in combination with another ore and heating it to a melting temperature or higher. The present invention has been completed mainly based on these findings.

That is, in the method for producing ferroalloys in an electric furnace according to the present invention, in producing ferroalloys by melting and reducing raw ores by an electric furnace, first, melting of raw ores is started by the above-mentioned high temperature load test. Based on the knowledge that the temperature and the burn-through end temperature can be relatively accurately determined, the melting start temperature and the burn-through end temperature of the raw ore are previously measured by a high-temperature load test. As a result, the melting temperature range is easily obtained from the difference between the melting start temperature and the burn-through end temperature, and the value is relatively accurate.

Next, based on the data of the melting start temperature and the melting temperature range, a raw material ore having a melting start temperature of 1300 to 1500 ° C. and a melting temperature range of 200 ° C. or less is selected, and the raw material ore is dissolved in the raw material ore. 85% or more of the total amount of ore is dissolved. Therefore, most of the raw ore to be melted has a melting temperature range of less than 200 ° C and is narrow, so that the raw ore in the electric furnace has a narrow softening cohesive zone. As a result, the electric resistance of the raw material in the electric furnace decreases, Phenomena such as floating and difficulty in applying a power load are less likely to occur, so that operability can be stabilized and each basic unit can be improved.

[0012] The melting start temperature of the selected raw material ore is 13
The reason why the melting temperature range is set to 00 to 1500 ° C and the melting temperature range is set to 200 ° C or less is that the melting start temperature (1350 ° C or more) and the melting temperature range (200
(Within ° C) and melting temperature range and melting temperature range (approximately match)
By doing so, as described above, the softened cohesive zone is reliably narrowed, thereby stabilizing the operability and improving each basic unit. That is, if the melting start temperature is less than 1300 ° C or more than 1500 ° C, even if the melting temperature range is within 200 ° C, the melting temperature range shifts to the low or high temperature side with respect to that of manganese sintered ore, and The wearing is wide and the condition is bad. On the other hand, if the melting temperature range exceeds 200 ° C, even if the melting
This is because even at 00 to 1500 ° C., the softened cohesive zone is widened, causing trouble.

The raw ore (selected raw ore)
The reason why the mixing ratio (the ratio to the total amount of raw material ore dissolved in the electric furnace) is 85% or more is that if the ratio is 85% or more, even if the characteristics of other raw material ores are unknown, the amount of the ore is 15% or less. This is because the softening cohesive zone may be narrow because it is too small. However, if the raw material ore is less than 85%, the softening cohesive zone becomes wide and may cause trouble.

The raw ore which is not selected and excluded from the data of the melting start temperature and the melting temperature range, that is, the raw ore which does not satisfy the conditions of the melting start temperature: 1300 to 1500 ° C. and the melting temperature range: 200 ° C. or less. If used in large quantities in the state of raw ore, problems will occur. However, it has been found that the raw ore can be adjusted to a raw ore satisfying the above conditions by alone or mixed with another ore and heated to a temperature equal to or higher than its melting temperature, and the ore can be reformed. Therefore, after such adjustment (reforming), the ore can be sufficiently used as a raw ore containing the above 85% or more, and by doing so, the basic unit can be further improved and the raw ore is effectively used. You can do it. The heating can be performed using a sintering machine, pellets, or the like.

[0015]

FIG. 1 shows a high-temperature load test apparatus according to an embodiment of the present invention. In FIG. 1, A represents a raw material ore (hereinafter, referred to as a sample ore) which is a sample to be measured. The sample ore is heated while a constant load is applied to the sample ore, and the relationship between the temperature and the pressure loss is determined. By measuring, the melting start temperature and the burn-through end temperature of the sample ore are obtained, and the melting temperature width is obtained from these. At this time, in the relationship between the temperature and the pressure loss, as shown in FIG. 2, a temperature at which the pressure loss value sharply rises (pressure loss rapid rise temperature) is determined as a melting start temperature, and the pressure loss value decreases at a higher temperature, and the pressure loss increases. There is a temperature that is equal to the pressure drop value at the sudden rise temperature,
This temperature can be determined as the burn-through end temperature. And
The melting temperature width is determined from the temperature difference between the two.

The conditions of the above-mentioned high-temperature load test were as follows in the present embodiment. The size of the sample ore is 9.52 to 12.7 mm,
The amount of sample ore is 87.0 ± 0.1g, load on sample ore is 1kg / c
m ^2, and a mixed gas of N ₂ : 70% -CO: 30% was passed through the sample chamber as an atmosphere gas at a flow rate of 7.2 liter / min. Heating rate: 10 ° C / min up to 1000 ° C, 5 ° C thereafter
/ min, and slowly cooled after the burn-through was completed. In addition, the 10% shrinkage temperature, the maximum pressure loss value, the maximum pressure loss, and the like were measured in addition to the melting start temperature and the burn-through end temperature.

Sintered manganese ore, manganese lump ore C, manganese lump ore B, manganese lump ore A, and manganese lump ore A calcined ore (heat manganese lump ore A above its melting temperature, then cool and fire ) Are shown in Table 1.

As can be seen from Table 1, the manganese sintered ore has a melting start temperature of 1411 ° C. and a burn-through end temperature of 1535 ° C.
The melting temperature range is as narrow as 123 ° C. On the other hand, the manganese lump ore C has a melting start temperature of 1392 ° C and a melting temperature range of 157 ° C, and has good compatibility with the manganese sinter ore. The temperature is as low as 1292 ° C,
The melting temperature range is as wide as 206 ° C., and the compatibility with the manganese sintered ore is poor, which is inconsistent, and the manganese lump ore B is even worse. However, it can be seen that the manganese lump ore A calcined ore has good compatibility, and that the manganese lump ore A is also modified by calcination.

Next, various ores were used as raw material ores, and ferroalloys were produced by an electric furnace. When a mixture of manganese ore C and manganese ore C was used (mixed) as a raw material ore, both were well compatible as described above, so that they could be operated stably without any problem. On the other hand, when a mixture of manganese ore A and manganese sinter is used, when the compounding amount is 100 kg / T (that is, 10%), the electrode floats, it is difficult to operate stably, and 250 kg / T (Ie
(25%), the electrode floated (the position of the holder after tapping was rising), and the unit power of melting power deteriorated. On the other hand, when the mixture of manganese ore A and calcined ore in manganese sintered ore was used, the operation could be stably performed without any trouble regardless of whether the compounding amount was 100 kg / T or 115 kg / T. .

Among the ores tested in the above-mentioned high-temperature load test, when manganese lump ore B, which has the poorest compatibility, is used for silicomanganese (SiMn), when the amount is 50 kg / T, Although stable operation was possible without any problems, 10
Operating results at 0 kg / T (Si yield, slag loss Mn%,
(Dissolution power unit) deteriorated. Further, when the pressure is set to 200 kg / T, the deterioration of the operation results further progresses,
It was difficult to discharge slag at the time of tapping, a large amount of coke was discharged together with the slag, and tapping work was extremely difficult.

[0021]

[Table 1]

[0022]

According to the method for producing ferroalloys in an electric furnace according to the present invention, the melting start temperature and the melting temperature range of the raw ore are determined by a high temperature load test, and the melting starting temperature is 1300 to 1500 ° C and the melting temperature range is Ore is selected within the range of 200 ° C, and the ore is melted by containing 85% or more of the total amount of the dissolved ore, so that most of the ore used for melting has a melting temperature range of 200 ° C or less. The ore in the electric furnace has a narrow softening cohesive zone because it is narrow, and as a result, phenomena such as a decrease in the electric resistance value of the raw material in the electric furnace, floating of the electrode, and difficulty in applying the electric power load are less likely to occur. Therefore, there is an effect that the operability can be stabilized and each basic unit can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically showing a high-temperature load test apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram exemplifying a relationship between a temperature of an ore, a shrinkage ratio, and a pressure loss in a high-temperature load test.

[Explanation of symbols]

 A-Sample ore

Claims (2)

(57) [Claims] When a raw ore is melted and reduced by an electric furnace to produce ferroalloys, a melting start temperature and a melting end temperature of a raw ore are measured in advance by a high-temperature load test so that a melting start temperature of 1300 to 1300 is obtained. An alloy in an electric furnace, wherein a raw material ore having a melting temperature range of not more than 200 ° C. at 1500 ° C. is selected, and the raw material ore is contained by melting at least 85% of the total amount of the molten raw material ore. Iron manufacturing method. 2. A raw material ore that does not satisfy the conditions of a melting start temperature: 1300 to 1500 ° C. and a melting temperature range: 200 ° C. or less is heated to a melting temperature or higher to adjust the raw material ore to satisfy the conditions. The method for producing ferro-alloy in an electric furnace according to claim 1, wherein the iron ore is used as a raw material ore containing 85% or more.