A twenty-tray single bubble-cap column was used to air strip ammonia and methanol from a synthetic, as well as a plant wastewater stream. When feeding synthetic solutions containing $700 mg/kg ammonia, stripping efficiencies of more than 98% were achieved at gas to liquid mass ratios (G/L) ratios of 2.5-2.7. This produced stripper bottom solutions contains $10 mg/kg ammonia. Reducing the air flow by 25% increased the ammonia content in the stripper bottoms to $30 mg/kg.Using the graphical McCabe-Theile method, the overall column efficiency for the bubble cap column during ammonia stripping was between 9 and 26% because of the low contact efficiency of this column.When treating the ''as received'' plant wastewater, the ammonia removal efficiency was only 84% at the lower G/L ratio. This increased to 99% by raising the pH from 9.8 to 11.5 and increasing the G/L mass ratio.The ammonia volumetric mass transfer coefficient (K L a) for these tests was calculated to be between 0.38 and 0.58 h 21 . Both stripping and absorption of methanol occurred in the column during stripping of ammonia. Based upon solution analyses, the methanol removal efficiency varied between 55 and 95%.

A characterization study of chromite ore from South Africa was conducted using bulk assays, X-ray diffraction, optical, scanning electron microscopy (SEM), automated electron probe microanalysis (EPMA) and quantitative evaluation of mineral by scanning electron microscopy (QEMSCAN) mineralogical techniques, and quantitative EPMA. The aim was to identify all major gangue impurities, the degree of chromite liberation, and possible beneficiation options. The bulk material assayed 40.5% Cr2O3 with the major impurities being Al2O3 (13.2%), MgO (12.1%), and SiO2 (7.5%). Quantitative mineral phase analysis showed that the sample mineralogy was dominated by a chrome-rich spinel phase with an average chemical composition (in wt.%) of: Cr2O3—47.8; FeO—26.0; Al2O3—15.4; and MgO—11.0. Contaminant phases included siliceous minerals enstatite, anorthite-rich plagioclase (bytownite), Cr-rich diopside (containing 1–2 wt.% Cr2O3), and phlogopite mica. QEMSCAN analysis of sized fractions indicated that (a) most silicate gangue species were in the +850 μm fractions, (b) the chrome-rich spinel in all fractions was >80% liberated, and (c) the most common mineral association for chromite was with enstatite. Based on the results, upgrading test work demonstrated that stage crushing followed by wet gravity concentration produced a chemical–metallurgical-grade ‘chromite’ product containing >46% Cr2O3 and <1% SiO2.