The Drying Principle and Technological Measures of Non-fired Phosphate Bricks

Refractory bricks usually need to be fired during the production process to ensure their mechanical properties and chemical stability. However, non-fired phosphate bricks do not use sintering and can achieve their dry basis by other means.

Non-fired phosphate bricks have good chemical stability, high thermal strength, and good wear resistance. They are often used as the expansion port of the shaft kiln, the lining of the high-temperature zone kiln, and the cooling zone and transition zone of the rotary kiln. The corrosion resistance of wear-resistant bricks is better than that of phosphate bricks, and they are often used in the parts with severe abrasion above the iron bricks of the shaft kiln and the cooler and kiln mouth of the rotary kiln.

Phosphate bricks use phosphoric acid solution with a concentration of 42.5% to 50% as a binder, and the aggregate is bauxite clinker calcined at a temperature above 1600°C in a rotary kiln. During the use of bricks, phosphoric acid reacts with the fine powder of fired bauxite in the bricks and refractory clay and finally forms a binder mainly composed of cristobalite-type aluminum orthophosphate.

The drying principle is mainly realized by the evaporation and discharge of water. During the drying process, the following technological measures can be adopted:

Control the relative humidity: In the production environment, by controlling the relative humidity, the moisture content in the air can be reduced and the drying speed of the bricks can be accelerated.

Heating: By heating the adobe, its surface temperature can be increased, and the evaporation and discharge of water can be promoted.

Ventilation: Ventilation increases the movement of air over the surface of the adobe and facilitates the drainage of moisture.

Adjusting the shape and size of the adobe: Adjusting the shape and size of the adobe can change its surface area and thickness, which affects how quickly the adobe dries.

It should be noted that unfired phosphate bricks may have a certain impact on their mechanical properties and chemical stability, so factors such as production costs and product quality need to be considered comprehensively when selecting a drying process.