Sintered dolomite mfr. in shaft furnace - using low grade fuel in preheating zone and with high thermal efficiency so overall fuel consumption is substantially reduced

摘要

Crude milled dolomite is moulded into pellets or briquettes fed down a shaft furnace to obtain sintered dolomite with a density above 3.0 g/ccm. The furnace has a top, preheating and de-acidification zone (a) at min. 1000 deg.C. heated by low grade fuel. Below zone (a) is a sintering zone (b) at 1600-2000 deg.C., heated by high grade fuel; and under zone (b) is a cooling zone (c). At least 60% of the cooling air used in zone (c) and thus heated is used as prim. air for burning the low grade fuel, which is pref. coal rich in ash; moist lignite; throat gas; waste oil; or coke dust. The remaining air leaving zone (c) is used to burn the high grade fuel, which is pref. coal or heavy oil contg. less than 2% sulphur. The total heat required in ca. 5000 kJ/kg sintered dolomite, which is only 80% of the energy normally required; and 60% of the energy is obtd. from low grade fuel.