Grate Pelletizing - An Operating Report and Process Comparison

CIM Bulletin, 1970

At its plant in San Juan, Peru, Marcona Mining Company operates two grate pelletizing furnaces for the agglomeration of 3.5 million long tons of magnetic concentrates annually. Line One, installed in 1963, was built by Lurgi as a downdraft process furnace utilizing a furnace fan for the recuperation of hot gases from the cooling zone. This line was modified in 1966 to include both updraft drying and downdraft drying, and the original roof burners were converted to side-wall burners. Line Two, a Dravo-Lurgi furnace with an annual capacity of 2.4 million long tons, was built in 1966. This line, in contrast to the modified Lurgi furnace, employs direct recuperation of hot gases from the cooling zone and utilization of process gases from the firing zone for updraft drying. Operating results are presented for the downdraft process Lurgi furnace and compared with performance after modification to an updraft drying - downdraft drying operation. Conversion resulted in better pellet quality, 15 per cent increased capacity, 30 per cent lower fuel oil consumption, and approximately 400 per cent reduction in grate bar and pallet corrosion. Firing of the pellet bed was improved by conversion from roof to side-wall burners. This modification also permitted utilization of monolithic refractory in place of pre-fired shapes, thereby improving over-all furnace availability and reducing refractory stock requirements from 154 different shapes to 18. Data are presented to compare operating performance of the Dravo-Lurgi furnace and the modified Lurgi furnace. These data show 30 per cent lower fuel oil consumption and 10 per cent higher capacity per unit g rate area for the Dravo-Lurgi furnace, which also averages higher a vailability due to greater operating flexibility.

Mots Clés: Cooling, Drying, Fans, filter cake, furnace, pellet, refractory, updraft, Furnaces, grate, Grates, Pellets, Process, Processes, Temperature