1. Selection of raw materials
The selection of materials for the overall pouring material of the molten iron ladle mainly considers three aspects:
(1) Has a high service life. Compared with brick lining, it is required that the pouring material has higher density and strength, better overall performance, and can better resist the erosion and erosion of high-temperature molten iron and slag.
(2) Has good construction performance. The pouring time is required to be easy to control, which can meet the construction needs of different seasons and has good vibration fluidity.
(3) Compared with fire-resistant bricks, it can meet the requirements of rapid baking and has a higher performance price ratio.
2. Determination of Particle Size Grading of High Aluminum Castable
In order to obtain high-performance castables, based on the experience of ladle castables, the particle size grading was strictly selected and controlled. The particle size of the aggregate ranges from 1 to 10mm, accounting for 65% to 70%. Select particles with a particle size less than 0.088mm, accounting for over 95%, as fine powder, with a dosage of 30% to 35%.
3. Selection of mixture
Considering the balance of calcium and silicon oxides in molten iron slag and castables, pure calcium aluminate cement aluminum can be selected as the binder of castables for molten iron ladle.
4. The influence of raw materials on the volume density of castable
The main reason for damage during the use of molten iron ladle is the infiltration of molten iron. When the reasonable particle size distribution is fixed, the influence of high-density raw materials and other additives becomes the main factor. The volume density of the castable increases with the increase of the grade of bauxite and the addition of aluminum powder.
5. The influence of binder selection on the performance of castable
The binder is the key to the castable, which not only affects the integrity and strength of the castable lining of the ladle, but also relates to the slag resistance of the ladle. Pure calcium aluminate cement is selected as the agent, because Al2O3, CaO and SiO2 in molten iron slag are easy to react with the acidic and alkaline substances of castables, balance the concentration of Al2O3, CaO and SiO2 in slag and materials, reduce the concentration gradient, thus reducing the possibility of this reaction and the adhesion phenomenon caused by this reaction.
6. Effect of aluminum powder addition on slag resistance of castable
The addition of aluminum powder has a significant impact on the slag resistance of the casting material, and the penetration of molten iron slag is generally around 3mm, with a maximum of 5mm. When the amount of aluminum powder added is 2%, the sample has the best resistance to molten iron penetration.
7. The effect of graphite on slag invasion
Due to severe slag sticking in the molten iron ladle, it is easy to cause mechanical damage during slag cleaning, which is also an important factor affecting the continued use of the castable lining. One of the main reasons for slag sticking is that Al2O3 and SiO2 in the castable react with CaO and other components in the slag to generate low melting point characteristics that adhere to the surface of the castable. In order to reduce this phenomenon, it can be overcome by adding a certain amount of graphite, especially when its addition amount is between 5% and 7%. At the same time, combined with measures such as good composition of the castable and reducing the porosity of the castable, the sticking phenomenon of the molten iron ladle is relatively light, and the effect of reducing the amount of slag sticking is good.
The castable prepared with special grade bauxite 2, aluminum powder, and additives has good physical and chemical properties, good resistance to molten iron penetration, and thermal shock stability, as well as good volume stability. Replacing the original shaped products on the molten iron ladle in a pipe casting factory can extend the service life of the ladle and reduce the labor intensity of workers.
