Dry Cleaning of Flue Gas Containing Asphalt from Anode Sintering Furnace

摘要

Carbon anodes for aluminum electrolysis plant are manufactured in its sintering shop. Anode Mixture of mainly coke breeze and asphalt as binder is molded into blocks with designed dimension, which are sent into furnace to be sintered at 1150℃. The sintering furnace is fueled by water gas. During sintering at high temperature, large quantity of flue gas emits. This sintering shop emits flue gas at 140,000-150,000 Nm~3/h, which composes of solid particles at 200-400 mg/m~3, asphalt fume at 200-300 mg/m~3 and SO_2, etc. The asphalt fume consists of liquid and gaseous phases. The gaseous phase is a mixture of various gases, and the liquid phase, droplets of condensed volatile of various hydrocarbons with particle size ranging 0.1-1.0 m. The entrained hydrocarbons are complex in composition which is roughly in accord with those in parent asphalt, an equally complex mixture of hydrocarbons. The hydrocarbons in flue gas consist of mainly polycyclic aromatics and small amount of heterocyclic compounds containing oxygen, nitrogen and sulfur. Among them, there are naphthalene, phenanthrene, anthracene, phenol, etc. It should be noted that the flue gas contains benzopyrene, a cancerogenic material, amounting up to 1.3-2.0 mg/m~3. Thorough clean-up of such flue gas is absolutely required. Secondary pollution should be avoided and concurrent recovery of usable materials considered.