The production process of mullite refractories mainly includes the following steps:

I. Preparation of raw materials

The main raw materials of mullite refractories include industrial alumina, siliceous raw materials (such as quartz sand and pyrophyllite) and some auxiliary raw materials (such as clay and sintering AIDS). According to different production processes and product requirements, other raw materials can be selected, such as coal gangue.

II. Treatment of raw materials

Crushing and grinding: Crushing and grinding raw materials to make them reach appropriate particle size. For example, the particle size of raw materials can be controlled at micron level by wet ball milling process to improve sintering activity.

Mixing and homogenization: all kinds of raw materials are mixed evenly according to a certain proportion to ensure the stability of chemical components.

III. Molding

The mixed raw materials are made into blanks by hydraulic molding machine or other molding equipment. In the molding process, appropriate amount of water or other binders can be added as needed to improve the strength of the green body.

IV. Drying

Dry the formed green body to remove excess water and reduce the risk of shrinkage and cracking during firing.

V. Firing

High-temperature calcination: put the dried blank into a high-temperature furnace for calcination. The firing temperature is usually between 1500℃ and 1700℃, depending on the requirements of raw materials and products. For example, high-temperature calcination in tunnel kiln can transform raw materials such as coal gangue into mullite.

Heat preservation and cooling: after calcination, the green body needs to be kept in the furnace for a period of time, and then slowly cooled to room temperature to ensure the performance of the product.

VI. Post-processing

According to the needs, the fired mullite refractories are further processed, such as cutting and grinding, to meet different application requirements.

VII. Quality inspection

Carry out quality inspection on the final product, including chemical composition analysis, physical performance test (such as compressive strength, porosity, etc.) and thermal performance test (such as thermal expansion coefficient, load softening temperature, etc.) to ensure that the product meets the standards.

VIII. Packaging and transportation

Packaging qualified products for transportation and storage. Common packaging forms include plastic woven bags and kraft paper bags.

IX. Innovative technologies and environmental protection applications

In recent years, some innovative technologies have been introduced into the production of mullite refractories, such as using industrial waste residue (such as coal gangue and fly ash) as raw materials, which not only reduces the production cost, but also realizes the recycling of resources. In addition, some enterprises also use chemical purge gas to replace traditional fuels, reducing energy consumption and carbon emissions.