What are the main points of the process of manufacturing fused zirconium mullite products?
The raw materials for the manufacture of fused zirconium mullite products are bauxite, soft clay, and zircon, and the mineralizer is magnesium oxide. The above-mentioned raw materials are added with water in a certain particle ratio to make mud material, which is pressed, dried and fired into blanks. The raw material ratio is: raw bauxite 64.5%, soft clay 23%, zircon 12.5%, water 4.5~5.5%. The fired blanks are broken to about 40mm and melted in a three-phase electric arc furnace. The working voltage is 110~140V, the working current is 1100~1500A, and the melting time is 2h. When melting, first spread 2~5mm coke on the bottom of the electric furnace to start the arc, add the broken blank billet, then add MgO mineralizer and powder to adjust the chemical composition of the material. The material can be cast after being melted at 1780~1800C. In order to ensure that the bulk density of the product is greater than 2.85g/cm’, supplementary pouring can be carried out.
The cast product should be cooled slowly and strictly according to the cooling rate. The physical and chemical properties of fused zirconium mullite products are as follows: Al2O: 60%, SiO24%, ZrO27~9%, flux 7.5%; bulk density 2.85g/cm3, compressive strength at room temperature 200MPa.
What are the operating points of manufacturing fused and cast AZS bricks?
The raw materials for the manufacture of fused and cast AZS bricks are alumina light sinter, zircon and waste clinker.
The alumina powder is lightly fired at 100℃, and the fine powder less than 0,088mm accounts for 50~70%. Moisture does not exceed 2%. Crush the waste clinker of the same material to the required particle size for use. Its ingredients are as follows: 50.3% of light-burned alumina powder, 46.1% of zircon concentrate, 2.2% of sodium carbonate, 1.4% of borax, and 20 to 30% of clinker. The powder is melted in a three-phase electric arc furnace, the working current is 2200A, the working voltage is 180V, and the melt temperature is 1800~-1840C. The melt is poured into the casting mold, and the bulk density is 3.4g/em*, and the ZrO2 content is ≥33 % AZS fused cast bricks.
What are the key points of the operation in the manufacture of AzS fired bricks?
The raw materials for making AZS fired bricks are zircon, industrial alumina (or super high alumina bauxite).
The zircon and industrial alumina powder were prepared according to 6; 4, plus 2% MgO. Grind the batches with a vibrating mill to less than 0.04mm for later use. After mixing and kneading the prepared batches, the blanks are pressed on a 300t friction brick press, and the clinker is calcined at 1400-1500°C. The clinker is crushed, pulverized, shaped and dried and fired at about 1600°C.
Why do cast AZS bricks crack? How to prevent cracking?
When the AI2O3 in the raw material exceeds 30%, the material is difficult to melt, which can increase the cracking rate of the casting. Therefore, the Al2O3 content should be measured before the raw materials are put into the furnace, so that it does not exceed 30%.
The input method of ingredients during melting directly affects melting. It is difficult to melt through one feeding, making
The product is easy to crack; a small amount of feeding is better.
When the melting temperature is too high or too low, the cracking rate of the product is high when it solidifies. In actual production, secondary smelting is implemented, that is, the material is melted at the melting temperature, and then the power is increased and the refining temperature is increased, which can reduce cracking when the product is solidified.
When the casting temperature is too high, the shrinkage rate increases during solidification, the temperature difference between the inside and outside of the product increases, and the product is easy to crack. Therefore, before casting, the arc is stopped for 3-~5min, and the refining temperature is lowered to the casting temperature (about 17600 ℃) before casting, which can reduce product cracking. In addition, the product should be cooled in an incubator. The temperature of entering the box should not be too low. For example, the temperature of 33° fused zirconium corundum entering the box is 1200 °C, and the cooling speed should be slow, and the temperature of leaving the box should not be higher than 300 °C. This is good for reducing product cracking.
