Aiming at producing a concentrate with a silica content lower than 1.00%, laboratory experiments were conducted using a sample of the concentrate from Samarco's mechanical flotation, which presented 3.08% silica content. This sample was split in two size ranges: +105mm and -105mm. The -105mm fraction, representing 76.69% of the initial mass, was submitted to another flotation, generating 0.61% silica content. The fraction +105mm, representing 23.31% of the initial mass, was ground 100% -105mm, deslimed, and submitted to flotation. Concentrates with 0.90% silica content were obtained. Considering the mass proportions of the two size fractions, the calculated silica content of the concentrate is 0.68%, which is considered satisfactory for the objective of this investigation. The major reasons for the 0.90% silica content are the presence of silicon in the lattice of goethites and the presence of residual slimes in the pores of porous hematite.
quartz flotation; iron ore flotation
