2023

Principle, Manufacture and Application of Light Bone Refractory Materials (Ⅰ)

Source: Network

The high-temperature industry is the basic industry for the production of structural materials (steel, glass, ceramics, etc.) and excellent functional materials (sensors, absorption materials, catalysts, energy storage materials, etc.).

The refractory lining is the basis of high-temperature industrial furnace, which plays a vital role in the efficiency and quality of high-temperature industry.

On the one hand, compared with radiation and exhaust gas, heat dissipation through the furnace lining is the main heat loss path adopted by industrial furnaces. Among them, the thermal insulation performance of refractory lining is one of the main factors that determine the energy efficiency and consumption of high temperature furnace.

Refractory lining, on the other hand, involves the entire high-temperature production process.

As a result, they can lead to unwanted inclusions in the product (I. e. steel, iron, alloys, glass).

In order to improve the quality and cleanliness of products, the development of durable refractory linings is a prerequisite. Therefore, the design of long-lasting energy-saving refractory linings is essential for the energy and resource efficiency of industrial furnaces and the quality of products.

Comparison of 1. traditional refractories and light refractories

traditional refractory materials

Traditional refractory materials are mainly composed of alumina, silicate, silicon carbide and other materials, which have the characteristics of high melting point, high hardness and high strength.

In high temperature environments, these materials can maintain stable performance and will not be melted or burned, thereby protecting industrial equipment from high temperatures.

Its manufacturing process is more complex, need to go through a number of processes, including the selection of raw materials, ingredients, molding, sintering and so on. As shown in Figure 1, the traditional refractory lining structure has a wear-resistant lining and an insulating layer.

The wear-resistant lining may resist erosion, abrasion, corrosion, and thermomechanical loading of the melt, while the insulating layer may reduce heat transfer through the refractory lining.

Traditional refractory materials are widely used, such as in steel smelting, glass manufacturing and ceramic production, traditional refractory materials are often used to protect equipment from high temperature and chemical corrosion.

lightweight aggregate refractory

With the advancement of industrial technology, some methods to extend the life of wear-resistant linings and reduce the thermal conductivity of insulating layers have emerged, which also brings two important problems:

1. Performance mismatch between aggregate and matrix

In order to improve the chemical, wear and thermal spalling resistance of the wear-resistant lining, researchers have sought to improve the purity, density and strength of the aggregates.

While this results in a longer service life of the wear-resistant lining, it also results in a performance mismatch between the aggregate and the matrix in the refractory material. Since the porosity of the matrix is higher than the porosity of the aggregate, damage and degradation will preferentially occur at the matrix of the refractory material.

2. The use temperature of nano insulation board can not meet the requirements

The traditional application of thermal conductivity is lower than the air of the nano-insulation board, the higher temperature of the nano-insulation board below 1000 degrees C.

However, for most steel-making industrial furnaces, the temperature of the interface between the insulating layers is 1000-1200°C.

The crushing, degradation and failure of the nano-insulation board only generate heat after 3-5 heating cycles, which greatly reduces the thermal insulation performance of the lining.

In order to overcome the above two problems, the idea of lightweight wear-resistant lining refractories based on lightweight aggregate came into being.

On the one hand, since the matrix is the weaker part during the use of the refractory, an aggregate with too high a density is usually not required.

Energy and resource consumption can be reduced by replacing traditional dense aggregates with lightweight porous aggregates.

On the other hand, the thermal conductivity of the wear-resistant lining can be reduced by using lightweight porous aggregates.

In addition, the temperature field distribution of the refractory lining can be optimized to reduce the interface temperature between the insulating layers to an acceptable value for the nano-insulating board.

Thus, the required temperature can be significantly reduced by the heat dissipation of the liner. More importantly, the superheat of the molten melt can be reduced, thereby improving the quality of the product.

There have been many studies on light bone refractory materials:

For example, a low-density spinel-alumina ladle-cast lightweight wear-resistant lining refractory can be made using porous alumina as an aggregate; a series of lightweight porous aggregates (alumina, mullite, spinel and cordierite) can be prepared by in-situ pore formation techniques.

Key words:

Principle, Manufacture and Application of Light Bone Refractory Material