How is refractory brick formed?

How to form refractory bricks, in order to reduce the porosity of refractory bricks and improve the quality of refractory bricks, it is necessary to increase the molding pressure. For ordinary refractory bricks, the forming force should reach 137 MPa: the forming force of high-density refractory bricks should be in the range of 176-215 MPa. In other words, this effect can only be achieved by molding with a squeezing brick press of 250t or more. The porosity of the refractory brick should meet the following requirements ≤ 23%.

 

The refractory brick is formed and dried, and the moisture content of the formed brick is generally above 3.5%. It cannot be immediately burned into the kiln and needs to be dried to reduce moisture. The drying system of the green body varies depending on the molding method of the green body and the single weight. The green body formed by the semi-dry method should be dried in a tunnel drier. The hot air temperature is 140-160 ° C, the exhaust gas temperature is 60-90 ° C, and the residual moisture of the blank should be less than 2%.

 

The blanks formed by hand molding, hammer hammering and vibration molding should be naturally dried first. The drying time varies depending on the weight of the individual. For a blank weighing less than 10Kg, it can be naturally dried for 16~24h: 10~25Kg, naturally dried for 36~40h, for a single weight of 25~40kg, naturally dried for 72~96h. During the month of the blank, the natural drying time should be longer. The naturally dried body can be dried in a desiccator. The hot air inlet temperature of the dryer is 100~120 °C: the exhaust gas temperature is 60~80 °C.

The most important question is the firing temperature of refractory bricks? When fired in a downdraft kiln, the general firing temperature is 1390~1400 °C, and the heat preservation is 24~32h.

 

The rate of temperature rise varies with the materials and products. The low temperature stage before 600 °C should be slowly heated: 600~1200 °C, the heating rate can be slightly faster: 1200 °C to the highest firing temperature should control the heating rate. The cooling phase also controls the cooling rate.

 

Refractory brick kiln (or kiln car) is generally used in paperback. To avoid black spots during firing, side mounts are also available. If it is fired in the tunnel kiln, the kiln car top can be flattened with high-aluminum clinker sand. In order to make the brick sturdy, it is necessary to pull a layer of pad at a certain height. The height of the brick is generally 650~1000mm.

 

If you are interested in our refractory bricks, you can contact Sunrise Refractory Company and we will get in touch with you as soon as possible.