Lightweight Insulating Bricks for Ladle Insulation

The ladle utilizes insulating lightweight bricks. In addition to the working lining, the ladle also has a permanent layer to ensure leak-proof design. The insulation thickness is generally designed by reducing the thickness of the permanent layer. For example, a 200t ladle has a 170mm working lining and a 90mm permanent layer. Reducing 20mm for insulation leaves a 70mm permanent layer.

Lightweight Insulating Bricks for Insulation

Due to concerns about the pulverization of nano-insulation panels and cost considerations, some general contractors and steel mills are using insulation bricks in their ladles. Some utilize one or two layers of bricks atop fiber insulation panels, using lightweight mullite or corundum bricks, which have a lower alumina content. These are similarly prefabricated with partially recycled materials. Commercially available bulk densities range from 1 to 1.5 g/cm³. Compressive strength is approximately 20 MPa, and thermal conductivity is approximately 0.5 W/(m·K).

What is the effectiveness? The thermal conductivity and thickness of the material can be used to estimate the effectiveness. The thermal conductivity of nano-insulation panels is approximately 0.045 W/(m·K), while that of fiberboard is approximately 0.15-0.2 W/(m·K). Insulating bricks are less effective. However, compared to the 0.9-1.1 W/(m·K) thermal conductivity of the permanent layer's high-alumina castable, they still have the effect of reducing the surface temperature of the steel shell.

The thermal conductivity of a material depends on its composition, such as clay, high-alumina, mullite, or corundum. It also depends on its density, porosity, shape, and quantity.

Based on the performance of lightweight clay bricks, can they be used in ladles? They should be, as fiberboard also has low strength. However, due to construction and application considerations, the strength may be lower.

Lightweight high-alumina bricks offer superior refractoriness to lightweight clay bricks, and increasing density will result in higher strength. Given the high temperature of the molten steel, lightweight high-alumina bricks may be more suitable.

The microstructure of lightweight high-alumina bricks reveals a high number of both open and closed pores. While they are suitable as thermal insulation materials, their ability to withstand even temporary molten steel loads as working linings is very limited.

The use of low-cost materials that balance economic efficiency and energy-saving performance as insulation materials is worth considering. The challenge lies in ensuring profitability for manufacturers and a worthwhile return for users.

The cost and manufacturing process of traditional lightweight bricks are well-known. For ladles, thin bricks also require consideration of their curvature. General contractors producing for their own use will consider cost and economic viability. Energy savings can be achieved by lowering converter tapping temperatures, reducing costs. If the results are stable, rollout will be successful. However, if the results are inconsistent and unsustainable, it's difficult to expect the owner to increase material costs.

Ladle insulation is located in a permanent layer, ensuring both energy efficiency and safety. Contact RS Refractory Brick Manufacturer for more quotes on ladle refractory products.