KR100203462B1 - Castable - Google Patents

Abstract

The present invention relates to a basic high-strength castable, particle size 5-3mm sintered magnesia clinker 19-21wt%, particle size 1mm or less sintered magnesia clinker 19-21wt%, fine sintered magnesia clinker 20-22wt%, particle size 3- 1mm magnesia-rich clinker 24-26wt%, ultrafine alumina powder with average particle size of 5μm 7-9wt%, silicon oxide composite binder 3-5wt%, purity 70% alumina cement 1-3wt%, azodicarbon amide ) Castable using a large amount of alumina cement, composed of 100wt% of raw and subsidiary materials composed of 0.01-1wt%, reducing the amount of alumina cement used and reducing the strength and fire resistance due to decomposition of hydrate in the temperature range around 800 ~ 1000 ℃. It improves the problems such as deterioration, develops strength by using ultra fine powder, maintains the strength even in the middle temperature range, and adds low cement magnesia castable with high fire resistance. Ever applied by it with a superior effect in terms of strength properties and Nass polling resistance and corrosion resistance.

Description

Basic high strength castable

The present invention relates to a basic high strength castable, and more particularly, to a basic high strength castable having excellent strength characteristics at medium temperature, and excellent spalling resistance and corrosion resistance.

In general, the castable (Castable) has become wider range of use due to its ease of use. Currently produced castables can be broadly classified into adding chromium ore and adding a large amount of alumina cement as a binder or a phosphoric acid binder as a magnesia binder to add volume stability to the magnesia. However, such castables have a weak strength at low temperatures, low fire resistance, and their use range is limited. Therefore, in order to improve the weakness of these castables, the present invention imparts its own advantages of high melting point, high fire resistance, high chemical stability and high corrosion resistance to basic slag or alkali material and high disadvantage of magnesia refractory material. Improved low spalling resistance, risk of collapse due to hydration during drying, high thermal expansion rate and low volumetric stability, requiring refractory materials that can be supported for the required lifetime even under other harsh working conditions such as zinc fumer. It became.

At this time, the zinc fumer blows coal raw material, oxygen and compressed air through a lance to purify about 15% of zinc contained in the slag by using horizontal slag discharged from the primary refining furnace of zinc ore as a charging raw material. To burn. At this time, the operating temperature is a process of subliming at about 1600 ℃ by splashing water on the separated zinc, cooling and separating the application area, since it is difficult to install the duct in the ceiling area where the lance passes. Although it is used in construction, since the dropout is severe, it is installed as far as possible around the lance hole, and the air gap is cast as a cast. As a cause of the dropping, when the lance is replaced at the operating temperature of 1600 ℃, it is cooled to about 700 ℃ by contact with the atmosphere around the lance, and the thermal sprinkling due to the difference in thermal expansion rate due to the temperature difference between the inside of the cooling water flows between the shells. It is known that the slag scattered during the operation of the furnace and the construction body are dropped due to the structural spalling caused by the difference of physical properties between the desintered deteriorated layer and the raw layer due to contact, and the castable weight due to the deterioration of the strength of the back. .

Accordingly, the present invention has been made to solve the above problems, the castable using a large amount of alumina cement is a problem such as a decrease in strength and fire resistance due to decomposition of the hydrate in the medium temperature region around 800 ~ 1000 ℃ Therefore, the purpose of the present invention is to reduce the amount of alumina cement used, to express strength by using ultra fine powder, to maintain the strength even in the middle temperature range, and to provide a basic high-strength castable with a low cement castable having high fire resistance.

The present invention for achieving the above object is particle size 5-3mm sintered magnesia clinker 19-21wt%, particle size 1mm or less sintered magnesia clinker 19-21wt%, sintered magnesia clinker 20-22wt% of particle, particle size 3- 1mm magnesia-rich clinker 24-26wt%, ultrafine alumina powder with average particle size of 5μm 7-9wt%, silicon oxide composite binder 3-5wt%, purity 70% alumina cement 1-3wt%, azodicarbon amide ), Consisting of 0.01-1wt% raw material, characterized in that consisting of 100wt%.

1 is a comparative diagram showing the influence of the flow rate according to the amount of addition.

2 is a comparison diagram showing the difference in bending strength according to the derivative content in the general physical property test.

3 is a comparison diagram showing the hot line change rate for each temperature.

Hereinafter, preferred embodiments of the present invention will be described in detail.

As a result of testing the flowability of each of the sub-materials in the content selection test of the additives added to the formulation, sodium phosphide had the best fluidity at 0.5%, but when it was added more, the fluidity decreased, and the silicon oxide-based composite binder In addition, when the added amount is increased, the fluidity tends to be improved, and when it is added more than 1.5%, the fluidity is not improved.In the case of phosphate-based binders, the fluidity increases with the added amount, but it is difficult to develop strength after curing. Sodium phosphate and silicon oxide-based composite binders were selected for this formulation because of difficulty in following.

In addition, by selecting the sodium phosphate 0.5% and silicon oxide-based composite binder 1.5% that had the best fluidity and changing the fine powder content to 25 to 40% as a result of measuring the change in the flow rate according to the addition amount, When the silicon oxide-based composite binder was used, the kneading was possible even at low water content, the fluidity was good, and when the fine content was 30%, a wide added moisture width was shown. Therefore, a silicon oxide composite binder was selected and the fine powder content was 30% and applied to the blending.

In addition, as a result of the compounding test to determine the type and content of the alumina ultrafine powder, alumina cement, and silicon oxide compound binder, which are used in the basic compounding, the ultrafine powder having a small average particle diameter was used at low additive amount. Good fluidity can be obtained, and fluidity tends to increase as the amount added. However, the smaller the particle size of the alumina ultrafine powder is, the more excellent in terms of fluidity and strength, but the price is higher, and the amount of addition is not reduced much compared to the ultrafine alumina powder having a particle size of 5 μm, and there is a problem of over-sintering at high temperature, so the average particle size is 5 μm. A powder of 8% was selected and applied to the formulation.

In addition, in the selection of the amount of alumina cement, as the alumina cement content is increased, the amount of added water tends to decrease and the fluidity tends to decrease, but the fluidity does not change significantly in the range of 0 to 5%. The smallest 2% alumina cement was applied to the formulation.

In addition, in the case of the silicon oxide-based composite binder, the fluidity increases and the drying and mesophilic strength increase rapidly even if the amount of addition decreases as the content increases. This is because the pores existing are filled to form a dense structure, and the high temperature strength is also accelerated and increased with the increase of the silicon oxide component. Therefore, in consideration of the effect on the flow rate and strength compared to the silicon oxide-based composite binder and other subsidiary materials, the silicon oxide-based composite binder was selected as 4% and applied to the blending.

The compound selection result was determined as shown in Table 1, and the characteristics improvement test was conducted.

FIG. 1 shows the influence of the flow rate according to the amount of added water. As the fine content decreases, the amount of added water decreases, but considering the flowability and strength, the fineness content shows good fluidity and strength.

2 shows the difference in bending strength according to the differentiation content in the general physical property test, and the highest bending strength was shown when the derivative content was 35%, and due to the high thermal expansion of the magnesia refractory itself, Magnesia-rich clinker is applied to improve the weakness of tissue deterioration due to polling, and stress is generated by the difference between its coefficient of thermal expansion and the coefficient of thermal expansion of the surrounding matrix. It was able to improve the spalling resistance by mitigating. As a result of the application of magnesia-rich clinker by particle size, 3-1 mm was applied to show the best spalling resistance.

When the azodicarbon amide, an organic foaming agent, is added through other tests of explosion resistance, hydrolysis occurs during magnesia and construction, and gases such as nitrogen, carbon dioxide, and ammonia are generated, which increases the air permeability, and does not significantly reduce hot bending strength. Within the range of 0.06% of the azodicarbon amide showed the best ventilation rate.

3 shows the hot line change rate according to temperature, and shows a thermal expansion rate similar to that of the comparative example up to 1000 ° C., but at higher temperatures, the linear change rate rapidly increases due to volume expansion due to spinel formation of the matrix portion, and spinel above 1300 ° C. FIG. Shrinkage by sintering was greater than expansion due to formation, and shrinkage proceeded as a whole.

Hereinafter, more specific examples and comparative examples of the present invention will be described.

EXAMPLE

Sintered Magnesia Clinker 20wt% with particle size of 5-3mm, 20wt% of Sintered Magnesia Clinker with particle size below 1mm, 21wt% of Sintered Magnesia Clinker with fine grain, 25wt% of 3-1mm Magnesia-Rich Clinker with particle size, 8μm ultrafine powder %, Silicon oxide composite binder 4wt%, purity 70% alumina cement 2wt%, Azodicarbon Amaid (0.06wt%). Basic high strength castable, characterized in that it consists of 100 wt% of an auxiliary material.

As a result of the above characteristics improvement test, the compound and the amount of the compound were finally determined as shown in Table 2 below, and the results of comparative analysis were performed by showing the chemical composition analysis and the measurement results of the general physical properties as shown in Table 4 below. In the same manner, the results were excellent in terms of strength properties, spalling resistance and corrosion resistance.

As described above, the basic high strength castable according to the present invention had excellent overall strength characteristics at 100 ° C. or higher, and excellent results compared to the two comparative examples of current products in terms of spalling resistance and corrosion resistance at 1400 ° C. In other words, it has the effect of extending the required life under severe working conditions.

Claims (1)

Particle size 5-3mm 19-21wt% sintered magnesia clinker, particle size 1mm or less 19-21wt% sintered magnesia clinker, 20-22wt% fine sintered magnesia clinker, particle size 3-1mm, magnesia-rich clinker 24-26wt% , 7-9 wt% ultrafine alumina powder with average particle size of 5 μm, 3-5 wt% silicon oxide binder, 70 wt% alumina cement 1-3 wt%, azodicarbon amide 0.01-1 wt% B.