Airtight paste (code name THM)
The airtight paste is a high-quality electrode paste used in an airtight submerged electric furnace . Sealing the furnace surface is the development direction of the submerged electric furnace. After the furnace surface is sealed, a large amount of combustible gas can be recovered, which is conducive to energy saving and improving the operating environment. However, the radiant heat is greatly reduced after the furnace surface is sealed , which is not conducive to the baking of the electrode paste , so it is required The closed paste has low ash content (not more than 6%), higher thermal conductivity and lower resistivity, which is beneficial to increasethe firing rateof the electrode paste . The production of airtight paste requires the use of high-quality anthracite raw materials, preferably electric-calcined anthracite, petroleum coke powder is used as the powder, an appropriate amount of graphite is added, and the softening temperature of the binder coal tar pitch is appropriately lowered.
Airtight paste can be divided into THM-1, THM-2, THM-3 these three indicators, the following table is the comparison of the technical indicators of airtight paste and standard paste:
Item number | index | Airtight paste ( THM ) | Standard Paste ( THD ) | ||
| 1# | 2# | 3# | |||
| 1 | Ash content ≤ | 3.5 | 4.5 | 6.0 | 9.0 |
| 2 | Volatile matter% | 9.5-11 | 11.5-12.5 | 11.5-12.5 | 11.5-13.0 |
| 3 | Compressive strength mPa≥ | 18.0 | 17.0 | 22.0 | 20.0 |
| 4 | Specific resistance Ω.m ㎡ ∕m | 65 | 75 | 80 | 90 |
| 5 | True density g/cm3≥ | 1.85 | 1.85 | 1.85 | 1.85 |
| 6 | Apparent density g/cm3≥ | 1.38 | 1.40 | 1.40 | 1.38 |
| 7 | Elongation% | 5-20 | 5-20 | 5-20 | 5-30 |
| 8 | Thermal conductivity w ∕mk | 8 | 8 | 8 | 6.5 |
| 9 | Than hot melt KJ/k.kg | 1.8 | 1.8 | 1.8 | 1.8 |