Basic Metal Benefication Process Plant

Crushing and Screening

Following blasting, the fragmented ore is loaded on a mining truck and hauled to the crusher for primary crushing. Many mines employ two to three stages of crushing. Some mines have the primary crusher located in the mine, using conveyors to transport the crushed ore to the secondary and tertiary crushers or directly to the mills. The crushing stages will reduce the iron ore from several feet in diameter at the primary stage to six inches down to one-half or threeeighths of an inch as a final product. The crusher product is fed to the milling operation for further size reduction.

Grinding

In the grinding circuit, rod, ball, or autogenous mills grind the taconite down into even smaller uniformed-sized particles. The ore is ground less than 325 mesh, and in some cases less than 500 mesh (45 - 25 microns) to help facilitate the liberation of the iron minerals from the rock.

Concentration

The product from the milling circuit is fed to the concentration circuit, where the valuable mineral is recovered and concentrated. Worthless gangue (sand and rock) is then separated. Using the magnetic properties of magnetite, magnetic-separation is the principal choice for taconite. Hematite ores are concentrated using conventional flotation. The concentrate is then filtered to remove water and passed to pelletizing and sintering operations.

Generally, the operations required before the iron ore is considered a finished product include:

• Crushing & Screening

• Grinding

• Concentration

• Agglomeration