Method for preparing refractory from secondary aluminum dross

A method for preparing a refractory from a secondary aluminum dross, wherein the secondary aluminum dross contains silica and alumina, and the refractory comprises a basic magnesium-aluminum refractory or an acidic magnesium-aluminum-silicon refractory;

• under the condition that the secondary aluminum dross comprises less than 5% by mass of silica, the refractory prepared is the basic magnesium-aluminum refractory, and the method comprises the steps of:
• subjecting a secondary aluminum dross powder, an aluminum source, a magnesium source and a magnesia-alumina spinel seed crystal to first mixing to obtain a first mixture, and
• subjecting the first mixture to one-step sintering to obtain the basic magnesium-aluminum refractory,
• wherein the aluminum source is an aluminum-containing compound;
• and
• during the first mixing, provided that a mass of the secondary aluminum dross powder is converted to and expressed in terms of a mass of alumina, a mass of the aluminum source is converted to and expressed in terms of a mass of alumina, and a mass of the magnesium source is converted to and expressed in terms of a mass of magnesium oxide, the mass of the aluminum source accounts for 2%-10% of the mass of the secondary aluminum dross powder;
• the mass of the magnesium source accounts for 20%-30% of the mass of the secondary aluminum dross powder;
• and a mass of the magnesia-alumina spinel seed crystal accounts for 0.1%-0.5% of the mass of the secondary aluminum dross powder;
• under the condition that the secondary aluminum dross comprises greater than or equal to 5% by mass of silica, the refractory prepared is the acidic magnesium-aluminum-silicon refractory, and the method comprises the steps of:
• subjecting a secondary aluminum dross powder, a silicon source, and a magnesium source to second mixing to obtain a second mixture, and
• subjecting the second mixture to one-step sintering to obtain the acidic magnesium-aluminum-silicon refractory,
• wherein the silicon source is a silicon-containing substance excluding the secondary aluminum dross powder;
• and
• during the second mixing, provided that a mass of the secondary aluminum dross powder is converted to masses of alumina and silica, a mass of the magnesium source is converted to a mass of magnesium oxide, and a mass of the silicon source is converted to a mass of silica, a mass ratio of magnesium oxide, alumina and silica in the second mixture obtained from the second mixing is in a range of (14-15):
• (36-37):
• (48-50);
• wherein subjecting the first mixture or the second mixture to the one-step sintering comprises the following steps:
• subjecting the first mixture or the second mixture to a first temperature rise from room temperature to a first temperature, and a first heat preservation at the first temperature to obtain a first pre-sintered material or a second pre-sintered material;
• subjecting the first pre-sintered material or the second pre-sintered material to a second temperature rise from the first temperature to a second temperature, and a second heat preservation at the second temperature, to obtain a first intermediate sintered material or a second intermediate sintered material;
• and
• subjecting the first intermediate sintered material or the second intermediate sintered material to a third temperature rise from the second temperature to a third temperature, and a third heat preservation at the third temperature,
• wherein the first temperature is in a range of 700° C.-850° C., and the first heat preservation is performed for 1 h-3 h;
• the second temperature is in a range of 900° C.-1000° C., and the second heat preservation is performed for 0.5 h-1.5 h;
• the third temperature to which a temperature of the first intermediate sintered material rises is in a range of 1700° C.-1800° C.;
• the third temperature to which a temperature of the second intermediate sintered material rises is in a range of 1250° C.-1400° C.;
• and the third heat preservation is performed for 3 h-4 h.