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Home -> News -> News -> Castable Technology ->

Research and application of steel ladle castable

Words:[Big][Medium][Small] Mobile Page Two-Dimensional Code 2018-10-15     

1, an overview of the

Ladle is a container, which plays an important role in the process of steelmaking. In order to improve ladle life and reduce the consumption of refractories, ladle refractories have developed from amorphous to amorphous refractories by variable and amorphous.Considering economy, labor saving and environmental protection, pouring construction has become an effective ladle construction method. The advantages of pouring construction also promote the development of ladle.In the eighty s of the 20th century in our country development of sodium silicate alumina magnesia castable began, and then develop the second generation without sodium silicate alumina magnesia castable, but still can't meet the molten steel temperature rise and the requirement of continuous casting ladle, development of spinel castable, such as alum clay spinel castable, magnesia spinel castable, aluminum spinel castable, etc. 


Laiwu iron and steel co., LTD. Steel mill, referred to as laiwu steel mill) in 750 T design of a month of castable now, feed manufacturers more (4), age 50 to 70 times, the difference is large, quality instability, production and management inconvenience.Despite the overall contract, refractory consumption remains high.With the continuous development of steel production and market economy, the requirements for packaging age are becoming higher and higher.It is feasible to make full use of the existing idle equipment, improve the quality and stability of ladle castable and reduce the consumption of refractory material.2. Process research and raw material analysis and selection of various casting materials


According to the production practice of ladle refractory materials and abundant high alumina resources in China, high quality alumina clinker is aggregate, magnesia powder is selected, high alumina clinker powder, corundum fine powder, magnesia alumina spinel powder is the combination of matrix and inorganic binder. 

(1) after calcining bauxite clinker at 1500 ~ 1700℃ at high temperature, this material is composed of aggregate to ensure the volume carnosin of castable

(2) magnesium-aluminum spinel and magnesium-aluminum spinel are internal materials produced in the heating process, which can buffer thermal stress in the process of micro-crack growth and use, so its thermal shock resistance.At the same time, because more is castable in magnesium-aluminum spinel, thus has a strong inhibition on slag infiltration.The main chemical composition of the selected spinel is: al2o3:60 ~ 64% magnesium oxide: 28% ~ 32%.The amount of spinel can be determined from the relationship between the amount of spinel and erosion index, and the amount should not exceed 20%.

Table 1 chemical composition of bauxite

(3) add the intermediate magnesium oxide in the form of a fine powder.Add appropriate amount of magnesium base, the purpose is to produce slag resistance, excellent spinel performance in the use process at 1200 ~ 1300℃, can also produce volume expansion into an overall amount.Its chemical composition is: magnesium oxide = 95%;SiO2 = 2%;Cao = 1.6%;Cautery = 0.3%;Over 3.25g/cm3 volume density.With the addition of magnesium, the expansibility increases significantly and the intensity decreases after combustion.Add amount to be about 7% appropriate. 


(4) as ladle castable (additive) materials, such as: pure calcium aluminate powder, oxide ultrafine powder, silica sol, alumina sol, phosphate, phosphorus, alumina or multi-purpose pure calcium aluminate cement, polyphosphate and oxide ultrafine powder.The ratio of pure calcium aluminate cement to castable is the same as that of ordinary calcium aluminate cement, but the purity of calcium aluminate cement is high, the chemical composition is mainly alumina and calcium oxide, and the impurity content is very low.Industrial alumina and pure limestone or calcite, or industrial calcium phosphate are used as raw materials.The main mineral composition is calcium aluminate (CaO 2Al2O3) and a small amount of calcium aluminate (CaO, Al2O3).The coagulation rate is normal, the initial setting time is about 1h, and the final setting is 6 ~ 8h.

Sodium polyphosphate is a common binder for basic refractories. It is characterized by a very strong binding, the intrusion of phosphorous forming binders in contact with slag and smaller molten metals, and good thermal shock stability. 


The characteristics of oxide (silica fume, alumina) ultrafine powder are based on the theory of surface phenomenon. Due to the existence of surface energy, fine powder has dispersion - aggregation effect.


According to different functions of bonds, pure calcium aluminate cement, sodium silicate and other composite binder are selected. 


(5) selection of additives.In order to make the casting material have good dispersion, low fluidity and low temperature, silica fume is used as additive.When silica fume is added to calcium aluminate cement, alumina, magnesium oxide powder, low temperature can change the original hydrate and they form new hydrate, hydrate formed network chain, its form is maintained at 1100 ~ 1200℃, to ensure that they have a very high temperature after burning the cold state strength.The results show that silica powder can not only improve the intermediate temperature intensity, but also bring a series of factors affecting the high temperature performance.The amount added should be in the range of 2% to 0.5%. 


Foreign experts think: the addition of silica fume, and calcium aluminate cement reaction is not pure calcium aluminate cement to form CAH10 and C2AH8 and C3AH6 and hydrate, but the formation of zeolite calcium aluminate hydrate, dehydration at 300℃ hydrate, and in a short time, a lot of steam quickly release and lead to burst.For this purpose, explosion - proof agent is added into casting material.Determination of raw material particle size distribution 2.2 quality depends on the size of the aggregate quality of the castable, the composition of the aggregate and the powder, the additives, the water content and the curing temperature.Sintering full density, density, low porosity, low impurity content requirements.Aggregate size ratio for the most compact design.Multiple components should be adopted to prevent particle separation. The assembly consists of aggregate about 70% and powder (including additives) about 30%.


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