Applications of monolithic refractory materials in various industries

1. Characteristics of castable precast blocks

Castable precast blocks require only low-temperature heat treatment, making them low-carbon and green refractory materials, and a unique technology in refractory lining. They can improve the performance of refractory linings, reduce refractory material consumption, and offer stable quality and reliable performance. We know that adding steel fibers to castables aims to improve their mechanical properties, inhibit crack initiation, or limit crack propagation when they do form.

2 Applications of monolithic refractory materials in blast furnaces

Blast furnaces are crucial equipment in ironmaking. Small blast furnaces were previously constructed using high-alumina cement and high-alumina phosphate refractory precast blocks. But now resin-bonded alumina-carbon unburned bricks are commonly used. Large blast furnaces use SiC castable rammed earth for water-cooled walls. While the furnace bottom layer and surrounding brick joints use refractory castables and silicon nitride fillers. A developing trend in refractory materials for furnace walls is the adoption of castables.

Currently, the main type of unshaped refractories used in blast furnace tapping troughs both domestically and internationally is Al2-O3-SiC-C (ASC). Other types include mullite-SiC-C, Al2O3-C, and magnesium aluminum spinel. my country primarily uses corundum-SiC castables. In Japan, most blast furnace tapping troughs now use ASC castables and repair spraying materials. While some small blast furnaces use bauxite or synthetic mullite-SiC-C ramming mixes. Germany and France also generally use ASC ramming mixes in their blast furnace tapping troughs. France has developed self-flowing castables, which have improved the service life of the main tapping trough lining.

3. Application of unshaped refractories in steel ladles

The increase in tapping temperature and the extended residence time of molten steel in the ladle have led to significant changes in the refractories used in steel ladles. Steel ladles were once primarily constructed with shaped refractories, but are now being replaced by unshaped refractories. The amorphous design of steel ladles saves labor and enables automated factory construction and drying, improving overall economic efficiency. When the ladle sidewalls are amorphous, maintenance work can be reduced by 40%. when the ladle lining is entirely amorphous, the labor-saving effect reaches 70%. Al2O3-spinel castables have advantages. Such as good corrosion resistance, minimal structural spalling, long service life, and the ability to improve steel quality, making them a major player in current ladle refractory materials. However, their use is limited by temperature and molten steel residence time. The Al2O3-MgO castable developed by Kawasa-ki Corporation of Japan has improved material strength and slag penetration resistance, and its service life is 20% longer than that of Al2O3-spinel castables. Currently, trials of magnesia-based and alumina-magnesia-carbon refractory castables on steel ladles are showing initial success.

4. Application of unshaped refractory materials in nonferrous metallurgy

Aluminum reverberatory furnaces are major consumers of refractory materials in aluminum plants. The refractory materials used in the furnace hearth have evolved from brickwork to integral structures. Refractory materials in contact with the hot metal of the furnace hearth are typically acid-base bonded plastics, phosphate-bonded bricks, and low-cement castables. The composition of the hot-face refractory materials for the lower sidewalls is usually the same as that of the furnace hearth. Insulation materials can be lightweight insulating castables, insulating clay bricks, or ceramic fibers. The furnace roof material is usually made of high-quality refractory materials such as rammed earth and castable refractory. The furnace door is usually made of dense castables or lightweight castables, or a mixture of both.

In electrolytic aluminum smelting, unshaped refractory materials are mainly used in aluminum ladles. The refractory materials used in aluminum ladles must be resistant to the erosion of molten aluminum, withstand rapid heating and cooling, and have good insulation properties. The non-working lining of the aluminum ladle generally uses lightweight castables or lightweight high-alumina bricks. If molten aluminum in aluminum drums is to be stored for a long period, insulating castables are typically used to prevent solidification during transport. Currently, to reduce the weight of the drums and enhance insulation, alumina hollow spherical refractory castables are used for the non-working linings. The working lining is generally constructed using high-alumina bricks with low SiO2 content; some drums now use corundum refractory castables.

In the copper smelting industry, because CuO, as a component of slag, is highly corrosive, basic refractories are widely used in roughing furnaces. For example, basic magnesia-chrome bricks or MgO-based basic ramming mixes are used in various parts of reverberatory furnaces, converters, flash furnaces, and rotary anode furnaces, especially during maintenance and repair. In the refining section, where slag volume and temperature decrease, aluminosilicate refractories such as castables, plastics, spray coatings, and high-alumina bricks can be used.