Question 1 – Description of Process for Iron Ore Mining and Taconite Pellet Manufacturing

The mining operation at Babbitt includes the drilling, blasting, and coarse crushing of the crude taconite 

ore. Taconite is a hard, low-grade iron ore containing iron oxide and silica. The iron oxide is magnetite, 

which is magnetic. The taconite ore supplied to the coarse crusher is blended in order to meet 

processing requirements. This is accomplished through the proper selection of the blast sites at the 

mine and the truck deliveries to the coarse crusher. Ore is removed from the mine pit by shovels and 

loaded into haul trucks that dump the ore into the crusher. Primary and secondary coarse crushing 

crushes ore to minus 4 inch size chunks of ore. Crushed ore is conveyed to an ore load out bin that 

releases ore into railcars to be shipped on a company owned railroad 47 miles to the Northshore Silver 

Bay taconite processing facility. A portable aggregate crusher is also employed at the mine and is used 

to crush aggregate for blast stemming, drill pad construction, haul road surfacing, or railroad ballast. 

Crushed ore received at the processing plant is unloaded with a rotary railcar dumper and conveyed to 

bins where it is housed until conveyed to the tertiary crushers. Tertiary crushing reduces the ore to -3/4 

inch chunks. The crushed ore is conveyed to dry cobbers where larger non-metallic chunks of ore are 

separated from chunks with higher iron ore content with magnetic separation. Cobbed ore is stored in 

bins until it proceeds to a series of rod and ball mills, magnetic separators, water hydraulic separators, 

flotation cells, and regrind mills that serve to concentrate the ore to achieve an iron content of 

approximately 62.5%. The iron concentrate is pumped to a slurry tank. The coarse tailings produced by 

these processes are hauled by rail to Milepost 7 and used to build dams and roads. The fine tailings are 

pumped to and deposited in the tailings basin. Recycled water from the tailings basin meets the process 

water requirements for the plant at Silver Bay.

The concentrate slurry of water and high-grade iron oxide particles is dewatered using disk filters in the 

concentrate filtering building. This process produces a filter cake of optimum moisture content for 

balling in the pelletizing plant.

The pelletizing plant provides the final stages of processing taconite ore into high-grade iron ore pellets. 

Prior to and in the balling drum circuit, additives such as bentonite clay, organic compounds, and 

limestone are mixed with the concentrate to improve the physical integrity of the green balls, or pellets, 

before and during firing in the furnaces. The additives also enhance the properties of the finished fired 

pellets for use in the blast furnace operation, the first stage of steel making.

After the balling drum circuit, the green pellets are conveyed to Furnace 5, 6, 11, or 12. There they are 

dried, fired at progressively higher temperatures, and then cooled. The finished fired-pellet product is 

conveyed through the pellet transfer area to the storage yard, a cooling pile or directly into bins and is 

then shipped to customers.