Characteristics and Utilization Value of Unburned Refractory Bricks

Unburned refractory bricks are refractory materials that can be directly used without firing. They have advantages such as energy saving, good thermal shock stability, and simple processing, which allow them to replace fired refractory products in a wide range of applications.

Unburned refractory bricks have many characteristics different from fired refractory products in terms of processing. These are mainly reflected in the following aspects:

1. Good Raw Material Calcination: Unburned refractory bricks do not undergo firing processes and are used directly after drying. Well-calcined raw materials can minimize volume changes during use, preventing cracking of the furnace body.

2. Reasonable Particle Size Distribution and High Molding Pressure: It is best to use granules with a flaky or angular shape, with a ratio of granules to fine powder of 7:3 or 75:25. A molding pressure of over 630 tons with more than 6 strikes is recommended.

3. Selection of Suitable Binders: Based on current usage, a single binder usually cannot meet the requirements, and composite binders are commonly used.

4. Selection of Additives: Unburned bricks undergo significant shrinkage during use, and delayed sintering on the surface may cause structural flaking, reducing the performance of the bricks. This can be partially addressed by selecting appropriate additives.

5. Control of Drying System: Proper control of the drying system is essential.

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The binding methods of unburned refractory materials are ceramic bonding or direct chemical bonding, where the hardening of the binder provides sufficient strength for the refractory material's use without the need for complex firing processes. The use of unshaped refractory materials eliminates the firing and molding processes, resulting in energy savings, increased production, improved product qualification rates, and reduced raw material consumption.

The simplification of production processes and elimination of complex processing restrictions inherent in ceramic or direct bonding have led to improvements in certain properties. The critical particle size of ingredients for unburned bricks or unshaped materials can be appropriately increased, significantly improving the products' thermal stability. Using binders such as phosphate salts, high-purity alumina cement, tar, resin, etc., not only reduces or eliminates the introduction of foreign impurities but also enhances the performance due to the advantageous final reaction products such as Al2O3, CA2, and C formed by chemical bonding. Additionally, the use of various additives and reinforcing materials such as steel fibers can produce unburned refractory materials with excellent properties such as slag resistance, resistance to CO and H2 gases, volume stability, high thermal strength, anti-spalling, and anti-creep.

The Utilization Value of Unburned Magnesia-Calcium Carbon Bricks:

1. 1.Due to their lack of firing requirements and superior performance, as well as their flexibility in structural design, unburned magnesia-calcium carbon bricks will become the main direction of development for this series of refractory materials.

2. 2.The development of unburned magnesia-calcium bricks is not only due to their superior technical performance but also because of their high economic benefits.

3. 3.The use and development of unburned refractory materials are of significant importance in the current situation of energy shortage.