PURPOSE: In ore reduction by CO at low temperature, the reaction of carbon deposition occurs violently.In a blast furnace, carbon deposit sometimes caused hanging.To clarify the kinetics of carbon deposition, this experiment was done in a stationary bed.
METHOD: In a standard state, next factors were chosen; ore-self-fluxing sinter, size-2.5mm-5mm, weight-50g, CO flow-1Nl/min, temperature-550°C, and these factors were changed one by one. A 41mm inner diameter porcelain combustion tube was used as a reduction tube.The furnace temperature was regulated automatically.Weight of deposited carbon and reduction degree were calculated by gas volume change and CO2 concentration change through reaction bed.
RESULTS: With a certain timelag, carbon deposit occurred at a constant speed of deposition.
The lower the temperature the higher the speed of carbon deposition, and the lower the temperature below 450°C, the delay time of carbon deposit rapidly increases. At the higher temperature the furnace pressure rose by the smaller amount of carbon deposit.
Carbon deposit occurred in a very thin layer.
Ore size little influenced the carbon deposit.
While the CO flow was not large, the speed of carbon deposition was proportional to the flow, but when the CO flow grew larger, it fell down from the proportional value.
In reduction by N2+CO gas, the speed of carbon deposition was proportional to the CO concentration and the delay time grew long.
In reduction by CO+CO2 gas, the speed of carbon deposition was proportional to (46-CO2%) and the delay time grew extremly long.
When some ballast was mixed in the ore, the speed did not change. But the furnace pressure rose slightly later.The furnace diameter did not influence on the speed of carbon deposition, but the furnace pressure rose by the carbon deposit proportional to the cross secton of furnace.
When heating at constant speed, carbon deposited under 760°C and dissolved over 760°C. Thereby the reduction degree improved very much;about 2g of carbon deposit was used by direct reduction, this was equivalent to about 25% reduction degree.(Received 13 July 1963)