| Zeta potential is an important factor in hematite processing. The magnitude of the zeta potential is a key factor in whether hematite particles in a slurry will coagulate or stay dispersed. Past researchers have focused on measuring zeta potential of high purity hematite surfaces in low ionic strength electrolytes. However, it is more important to know the zeta potentials that exist on hematite surfaces under plant conditions. Therefore, plant studies were carried out to measure zeta potential of hematite in plant water throughout an entire processing plant. The results found in this dissertation were significantly different than reported in past literature. A review paper was written to explain these differences. Carbon dioxide was found to significantly reduce zeta potential values at the plant. Conductance measurements showed that the effects of CO2 could be somewhat explained by increase in conductance, but were not entirely explained by this double layer compression. Fourier Transform Infrared Spectroscopy was used to identify hematite/carbonate complex formation after CO2 sparging. If similar to siderite, the formation of hematite/carbonate complexes would be expected to lower zeta potential in the observed manner. Overall, CO2 was found to have significant effects on the zeta potential of hematite slurries.;Phosphorus makes steel brittle, so it must be removed at the hematite processing plant. Most efforts to remove phosphorus from hematite at Plant A, involved flotation of apatite from hematite. The original goal was to use the above mentioned zeta potential measurements to determine if and where flotation would work. Due to the lack of background testing, the objective was modified to develop an overall strategy of for removing phosphorus from hematite. This four step strategy was implemented at Plant A. It was observed that flotation of apatite from hematite at Plant A was not the best method for phosphorus removal. Instead, efforts should be focused on improving the efficiency of the desliming processes, which already rejected 45% of the total phosphorus in the ore. |
