KR940002621B1 - Slag forming pacification sedative - Google Patents

Abstract

The fast stabilizer, comprises 25-55 wt.% cokes, 10-40 wt.% aluminum dross, 5-10 wt.% lime calcinated sludge, 5-15 wt.% blast furnace sludge, 5-15 wt.% convert furnace dust, and 5-10wt.% bentonite as a binder. The above cokes has its particle size of 0.4-3.2mm and has more than 80 % fixed carbon; the aluminum dross contains more than 30 % metallic aluminum and the calcinated lime sludge has more than 47 % calcium oxide. The blast furnace sludge has more than 55 wt% total iron and more than 20 wt% fixed carbon; the dust from converter furnace has more than 60 wt% total iron.

Description

Slag Foaming Fastener

The present invention relates to a slag forming sedative, and more particularly, to a slag forming rapid calming agent for rapidly calming slag foaming generated during molten iron desulfurization and converter conversion in the steelmaking process.

In general, during the charter pretreatment and converter blasting in the steelmaking process for the purpose of producing high quality steel, the blown gas reacts and is discharged through the slag layer to stabilize workability and increase refining efficiency.

However, because the silicon content is too high in the molten iron preliminary treatment process, or a large amount of silicon oxide is generated during the de-silicon treatment prior to the dephosphorization treatment (Si + O ₂ → SiO ₂ ), the slag layer becomes thick and the viscosity increases. The release of the blown gas and the reactant gas is disturbed, and as a result, the slag layer boils like a bubble and overflows. This phenomenon is called slopping.

In addition, in the converter blow process, the silicon in the molten iron is first oxidized after the oxygen injection, thereby increasing the concentration of silicon oxide in the slag, thereby preventing the release of CO, CO ₂ gas and blown gas generated during the decarburization reaction.

In particular, in the case of drilling molten iron having a high silicon concentration and sealing the upper part of the converter completely, attempts have been made, and the slag forming phenomenon during the drilling is applied to the sensor as the high speed blowing operation is performed to increase productivity. In the case of closed refining, it is impossible to visually determine the operator due to the flame state exposed to the upper part of the converter. Therefore, the prediction by the sensor is inevitable. Since it is delivered to the operator immediately before the sling due to the need for rapid calming of the slag calming body which eliminates the slag forming, the foaming phenomenon should be eliminated within 10 seconds after the injection. If the calming speed is not fast, even if the prediction of the slope is corrected, a large amount of slag will flow out of the converter gate, resulting in dust and flame generation, as well as poor workability and significant iron loss.

Up to now, sedatives with 80% pulp sludge, 15% ladle slag, and 5% bentonite have been used. However, due to the excessive amount of sedatives and 40 seconds of soothing time, a considerable amount of slag can be released during high-speed or closed refining operations. It is not there.

Japanese Laid-Open Patent Publication No. 59-48925 discloses a slag forming agent. The sedating agent is a mixture of 50-90% of pulse sludge and 5-25% of converter slag. Severe flames and dusts occur and the sedation rate is slow, so there is a flaw that calms down after a considerable overflow.

In addition, the sedatives disclosed in Ilbo Patent Publication No. 62-52004 include 20-25% calcium aluminate, 10-30% aluminum, and 10-20% carbon. Due to the high price of aluminum, there is a drawback of raising manufacturing costs.

In addition, the sedatives disclosed in Korean Patent Application No. 19988 filed Dec. 21, 1989, 15-30% of ladle slag, 5-15% of buncocos, 10-25% of jeon dust, 5-15% of calcined dust, Gorobeck The composition of filter dust 10-25%, pulp sludge 5-20% and bentonite 5-15% greatly reduces the flame and dust prevention time and soothing time from the conventional 40 seconds to 20 seconds. Although there is an effect to reduce to a level, there is a problem that can not completely eliminate the slipping phenomenon when the calming speed according to the anticipation of the slipping in the closed refining operation must be within 10 seconds.

The higher the content of the powdered coke in the patent application sedation, the faster the sedation speed, but the dust and flames are so severe that it cannot be increased more than 15%. It is therefore an object of the present invention to provide an improved slag forming tranquilizer that solves the drawbacks of conventional sedatives as described above.

The inventors found that aluminum dross, a by-product of industrial aluminum tablets, is much cheaper than expensive aluminum, and 31-36% of metal aluminum is contained in the aluminum dross. I countered that.

Based on this fact, according to the present invention, instead of the conventional powdered coke, the appropriate particle size is derived and the content is increased. Inexpensive slag forming sedatives are provided to soothe the slag forming phenomena generated during the first 10 seconds.

The slag forming sedative according to the present invention has a particle size of 0.4-3.2 mm and coke 25-55% having a fixed carbon of 80% by weight (hereinafter referred to as terminal%) or more, aluminum dross 10-40% of metal aluminum 30%, 5-10% of calcined sludge with 47% or more of calcium oxide, 5-15% of blast furnace sludge with T.Fe of 55% or more and fixed carbon content of 20% or more, 5-15% of total rust dust with T.Fe 60% or more, and bentonite as a binder Consists of 5-10%.

Among the components, coke has a fixed carbon of 80% or more, and reacts rapidly with oxygen to be released as CO or CO ₂ gas, or as the fixed carbon itself melts in the slag layer to increase fluidity, the gas generated due to a sharp drop in slag viscosity is generated. It acts to make it easier to break through the slag layer.

The kinetic effects of these chemical reactions and physical properties are most effective in the state of particle size of 0.05 mm or less, but the dust pollution generated during the injection is too severe and requires dust collection equipment or management. There is a problem with use because it is scattered.

Therefore, in the present invention, a method of adding coke having a constant particle size, which has a fast cooling rate and little dust, is required for application of a slipping prediction system when the particle size is in the range of 0.4-3.2 mm. Phosphorus shows 6.3-8.0 seconds within 10 seconds of phosphorus and has workability with little dust.

At this time, if the coke content is 25% or less, all of them act as chlorine materials and contribute to the improvement of slag fluidity, so the sedation rate is reduced. 25-55% is preferred because dust is generated.

Although aluminum dross is mainly composed of industrial alumina Al ₂ O ₃ , it has a metal aluminum content of 30% or more, which breaks the foaming of the slag layer in the process of reacting with high oxygen and 30 + 2Al → Al ₂ O ₃ in the composition. It is large in action and reacts with CO gas trapped in slag layer with 3CO + 2Al → Al ₂ O ₃ + 3C to drastically reduce the volume of gas. It is a very effective ingredient as a rapid sedative because of its impact and momentary phenomena. In addition, the alumina component in the aluminum dross has the alumina component in the forming slag together with the alumina after the metal aluminum reaction, so that Al ₂ O ₃ is added to the converter slag castable CaO-SiO ₂ -MnO-FetO system to improve fluidity. .

Therefore, the effect of the action is insufficient at less than 10% of the aluminum dross, the alumina component begins to interfere with the converter slag castability at 40% or more, the fluidity is rather deteriorated, the flotation of the non-metallic inclusions during ladle refining problem Since 10-40% is preferable. In addition, the calcined sludge, which is mostly calcium oxide and magnesium oxide, improves slag fluidity, and has an impurity removal ability to absorb some adverse reactions caused by coke, aluminum dross, converter dust, etc., and thus contribute to a considerable amount of molten iron. .

Therefore, the action force is insufficient at 5% or less, and at 10% or more, the effect of hardening the foaming slag layer is increased to give storage to the gas discharge. Blast furnace sludge contains more than 55% of iron and more than 20% of fixed carbon, and has both combustion material and oxygen source. Therefore, the amount of added sludge is calmed by promoting gas release of forming slag layer and rupture of forming slag layer by physical impact. Below 5%, the material balance between the combustion material and the oxygen source, and the slag calming effect due to the progress of Fe ₂ O ₃ + 2Al → Al ₂ O ₃ + 2Fe, which is a chemical reaction with metal aluminum in aluminum dross, are reduced. In the above, 5-15% is preferable because the converter refractory is eroded due to an imbalance in material balance and an increase in T · Fe content in the slag.

In addition, the electric furnace dust having 60% or more of iron contains solid oxygen required for the reaction of metal aluminum in the aluminum dross, the reaction of coke, and the combustion reaction with carbon in the blast furnace sludge, as well as the reduced iron grain drops the forming slag layer. It has a physical bursting effect. In the case of converter dust 5% or less, this effect is inadequate, and in 15% or more, 5-15% is preferable because it functions the same as when blast furnace sludge content is exceeded. In addition, bentonite is added for the purpose of binding the sedative compositions, and has an appropriate strength, so that the economic range of fine powder generation is 5010%.

Hereinafter, the present invention will be described through examples.

EXAMPLE

The slag forming sedatives (invention A, B, C, D) of coke, aluminum dross, calcined sludge, blast furnace sludge, conductive dust and bentonite having the chemical composition shown in Table 1 in Table 2 are Prepared with ash.

TABLE 1

Chemical composition of the main raw material of the present invention

TABLE 2

Composition ratio of the present invention and conventional materials

Forming slag is generated by inserting a certain amount of sintered ore while maintaining the casting vessel at a melting temperature of 1420 ± 10 ℃ in a 100kg high frequency induction furnace, and when the height reaches 20cm (the highest reaching height), the foaming is formed as shown in Table 2 above. The amount of sedating agent was added in the amount shown in Table 4 to measure the time required until the foaming was completely quenched, and the state of dust was visually determined at the time of injecting. Was investigated.

In addition, according to the invention material C of Table 2, the selection of coke particle size used as a means of increasing the coke content in the present invention, as shown in Table 3, the results of the coke particles 0.05 mm or less, 0.06-6.0 mm, forming calming effect and dust The optimum particle size without generation was 0.4-3.2 mm, and the results of the present invention and the prior art are shown in Table 4.

In Table 4, by evaluating the content of silicon oxide (SiO ₂ ) in the slag and the dephosphorization rate in the molten iron, the technical and economic effects of the metal sedative as well as the effects of the slag forming calming effect and the effect on the molten iron component behavior by the sedative To backstage.

TABLE 3

Calm time and dust generation status according to coke particle size (inventive C standard)

TABLE 4

As shown in Table 4, the present invention materials (A, B, C, D) are within 10 seconds of the required time of slag forming calm is 6.3-8.0 seconds, but the conventional materials require 38 times as much as the invention materials. As a side effect, the molten iron dephosphorization rate is 4% in the conventional material, and there is almost no difference in effect, but the inventive material has a dephosphorization effect of up to 17%.

In addition, the dust state in terms of workability and environmental pollution can be seen that the present invention is almost negligible, but the conventional material is extremely severe.

As described above, the present invention has a very short time for calming the slag forming, so that the control hit ratio due to the rapid calming effect is further improved during the application of the slope prediction system, thereby preventing equipment accidents due to the slope and their Eliminating manufacturing work and eliminating iron loss can reduce molten steel manufacturing cost. As a side effect, molten iron dephosphorization rate reaches 17%. Therefore, even when manufacturing low or ultra low-strength steel, the hit ratio is higher than before, contributing to quality improvement and sedative. Since there is almost no dust generated during the input, it is effective in providing safe supply of raw materials and inexpensive manufacturing cost by utilizing the by-products of steel mills and aluminum smelters as well as preventing environmental pollution.

Claims (1)

By weight, the particle size is 0.4-3.2mm, coke 25-55% with a fixed carbon of 80% or more, aluminum dross 10-40% with metal aluminum 30% or more, calcinium oxide 47% or more 5-10% with calcined sludge 5-15% of blast furnaces with at least 55% of T.Fe and at least 20% of fixed carbon, 5-15% of converters with at least 60% of T.Fe, and 5-10% of bentonite as a binder thereof. Slag foaming tablets.