Tieling Zhaohui Energy Saving Technology Development Co., Ltd.

Technical instructions of complexation magnesia alumina binder applied in mass production of carbon-free ladles bricks

Formulation:

Recommended addition of refractory brick aggregates: 70% (0-6mm; Fe<1%, Si<1%, Ca<2% by mass)

Recommended addition of refractory brick fines: 30% (180-200mesh)

Complexation magnesia alumina binder: 3%-3.2% (extra-adding or real portion)

Charging order:

Particles (aggregates) → adding water (producing proper wettability) →adding binder (producing adhesiveness) → adding fines

Detailed procedures:

Feed 70% of refractory brick aggregates into a mixer; turn on the mixer; add 1.8%-2.5% of water (the water absorption of aggregates shall be considered and producing proper wettability is the goal); pre-mix for 3-4 min (judge the wettability by the hand feel); add 3.5%-4% of complexation magnesia alumina binder powder, mix for 5-7 min (judge the adherence by the hand feel); add 30% of refractory brick fines and mix for 10-12min. The humidity shall be appropriate for the brick shaping. The green bricks are dried at 100 ℃-200 ℃ for 48h in a drying kiln. The residual water shall be less than 1%.

Notes:

1. Clean the mixer to remove the impurities. For example: if the mixer used to mix resin bonded materials, the residuals will react with the complexation magnesia alumina binder because of the different pH values. 

2 The temperature in mixing workshop shall be 15℃±5℃.

3 The friction press shall be over 630 tons.

4 Try to densify the green bricks; the bulk density of the finished bricks shall exceed 3.2 g•cm-3.

5 There are two key procedures: adding water and adding dry binder powder. For adding water, the water absorption shall be taken into account; for example, 1.8%-1.9% water addition is appropriate for corundum aggregates to reach the suitable wettability, while 2.0%-2.2% for bauxite aggregates. For adding the dry complexation magnesia alumina powder, the mixing degree shall not be judged by the time, but by the adherence (the hand feel is more visual); otherwise, the bonding properties of environmental-friendly binders for RH bricks and carbon-free ladle bricks will be reduced obviously, affecting the strength at room, medium, and high temperatures. The refractory brick fines shall be added after the appearance of the proper adherence.

6 Because the setting time of W3297BX binder is within 3 h and that of G3297BX is within 5 h, the mixed materials shall be used freshly, otherwise, the mixture will dry and affect the brick shaping.

Properties of carbon-free ladle bricks bonded by complexation magnesia alumina binder

Properties of Al2O3 based unfired bricks bonded by complexation magnesia alumina binder