Manufacturing and operation of zirconia mullite products.

Manufacturing process of zirconia mullite products.

The raw materials for the manufacture of zirconia mullite products are bauxite, soft clay, zircon, and mineralization as magnesium oxide. The above raw materials are mixed with water to make the clay, which is pressed, dried and burned into blank. The ratio of raw materials is 64.5% of raw bauxite, 23% of soft clay, 12.5% of zircon and 4.5 ~ 5.5% of water. The burned blank is broken to about 40mm, which is fused in a three-phase arc furnace. Working voltage 110 ~ 140V, working current 1100 ~ 1500A, melting time 2h. When melting, start with 2 ~ 5mm coke on the bottom of the electric furnace, add the broken blank, then add MgO mineralizing agent and adjust the chemical composition of materials. Material is 1780 ~ 1800 ℃ after molten casting can be performed. In order to ensure the product volume density is greater than 2.85g/cm3, it can be replenished.

The finished products should be cooled and cooled in strict accordance with the cooling rate. The physical and chemical properties of electrofused zirconium mullite products are as follows: Al2O360%, SiO224%, ZrO27 ~ 9%, flux 7.5%; Volume density 2.85g/cm3, normal temperature pressure strength 200MPa.

Key points of operation for making AZS bricks.

The raw materials for making AZS bricks are alumina light, zircon and waste material.

Alumina powder with 1100 ℃ lighter to burn, control is less than 0.088 mm powder accounts for 50 ~ 70% points less than 2%. Break the material of the same material to the required granularity. Its ingredients include: 50.3% of light - fired alumina powder, 46.1% of zircon concentrate, 2.2% sodium carbonate, 1.4% borax, and 20 ~ 30% clinker. Powder in three-phase arc furnace melting, the working current is 2200 a, voltage 180 v, liquid and temperature of 1800 ~ 1840 ℃. The molten liquid was poured into the mold, and the bulk density was 3.4g/cm3, and the ZrO2 content of the AZS fused cast brick with >33%.

The key to making AZS bricks.

The raw materials used to make AZS are zircon, industrial alumina (or super bauxite).

The zircon and industrial alumina powder are prepared by 6:4, plus 2%MgO. Use vibration grinding to be less than 0.04mm. After mixing practice in the batch of the preparation of 300 t friction brick molding machine crushing waste billet, mature material via 1400 ~ 1500 ℃ forging fire. Clinker after crushing, grinding, molding, drying at 1600 ℃ or so burnt.

Why does the melting AZS brick cause cracking? How to prevent cracking?

When the A12O3 in the raw material exceeds 30%, the material is difficult to melt, which can improve the cracking rate of the casting. Therefore, the content of A12O3 should be determined before entering the furnace, so that it should not exceed 30%.

Melting is directly affected by the input method of melting. It is difficult to melt at one time, the product is easy to crack; A small quantity of multiple inputs is good.

The melting temperature is too high or too low and the cracking rate is high when the product solidifies. In the actual production, the secondary smelting is carried out, which is to melt the material at the melting temperature, then increase the power, improve the refining temperature, and reduce the cracking when the product solidifies.

When casting, the casting temperature is too high, the shrinkage rate increases when solidification, the temperature difference inside and outside the product increases, the product is easy to crack. Therefore, before casting, stop arc 3 ~ 5 min, the refining temperature dropped to pouring temperature (1760 ℃) and then to cast, can reduce the products cracking. In addition, products should be kept in an incubator to cool. Into the box temperature shoulds not be too low, such as zirconium 33 # fused corundum into the tank temperature is 1200 ℃, cooling speed slower, should not be out of the box temperature higher than 300 ℃. This is good for reducing product cracking.