Buffering of pulp pH and its influence on process water chemistry during iron ore flotation
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Kunming University of Science and Technology
Min tang   

Kunming University of Science and Technology
Publication date: 2021-06-23
Physicochem. Probl. Miner. Process. 2021;57(4):157–167
It is inevitable for the occurrences of pulp pH buffering during pH control in flotation as the minerals with acidic/alkali properties tend to interact with pH modifiers and restore the pulp pH. This could result in some disturbing ions and alter the water/pulp chemistry. The purpose of this study was to identify the influences of pulp pH buffering on process water chemistry through a series of pH buffering tests, bench flotation experiments, ore dissolution tests, zeta potential measurement, and X-ray diffraction (XRD) analysis. The built-up and distribution of the dominant cations in the process water from different locations in an industrial flotation system of the iron ore were analyzed and recorded by Inductively Coupled Plasma-Optical Emission (ICP-OES) at a period of about six months when the operations were stable. The data showed that a near five-minute buffer of pulp pH at a range from near 7.9 to 8.9 occurred before it reached a stable value. At this period, the dissolution of Ca/Mg from the iron ore was dominant. And, the pulp pH at a lower value tended to induce more dissolved Ca2+ and Mg2+ ions. These divalent cations seem to have different influences on the flotation properties of iron oxides at the same concentrations, indicating a positive effect on the recovery of iron oxides with the presence of Mg2+ ions but an opposite effect if Ca2+ ions occurred. The presence of sulfate, however, tended to restore the floatability of silicate depressed by Ca2+ ions.