Keith Quast

A review of hematite flotation using 12-carbon chain collectors☆

Abstract A sample of naturally occurring, relatively pure hematite (98.5% Fe 2 O 3 ) was used as a model for the study of the flotation of insoluble metal oxides. The isoelectric point of this sample was 2.7 and the point of zero charge was 6.7. A number of surfactants containing saturated 12-carbon chain groups were used as collectors over a wide range in pH. The flotation of this hematite with dodecanoic acid (lauric acid) showed a maximum recovery in the pH range 6–8.5, a sudden drop at pH 9, and a steady increase in recovery as the pH was raised from 9–12. The flotation of the hematite using potassium dodecyl hydroxamate showed a maximum recovery at pH 5.5, with little flotation at pH pH >10, the recovery fell except at high additions of collector. The flotation of hematite using sodium dodecyl sulphate showed a high recovery for pH

Effect of grinding media and NaHS on copper recovery at Northparkes Mines

Abstract The flotation behaviour of copper minerals in the Northparkes Mines copper-gold ore is dependent on grinding media (and hence grinding Eh) and aeration during conditioning. Laboratory grinding and flotation tests were conducted using mild steel and stainless steel rods with and without the addition of sodium hydrosulphide (NaHS) in the conditioning stage. In the absence of NaHS, grinding using stainless steel media increased the kinetics of subsequent copper mineral flotation compared to the use of mild steel media. Flotation kinetics after grinding using mild steel media were increased by aeration prior to reagent addition. The addition of NaHS after grinding using mild steel rods increased the froth stability by increasing froth mineralisation, thus increasing the flotation kinetics of the copper minerals. When stainless steel grinding media was used, the copper flotation recovery was very high (>90 % in the rougher stage) without the addition of NaHS, so its use was not warranted. The flotation of the bornite was not reduced by oxidation, in fact copper mineral recovery was the highest under the most oxidising grinding conditions.

Leaching of atacamite (Cu2(OH)3Cl) using dilute sulphuric acid

The oxidised zone at the Mount Gunson, South Australia, copper mine contains copper in the form of atacamite. Copper at the Mount Gunson mine is currently being recovered by both heap and inplace leaching followed by cementation onto scrap iron. It was the purpose of this study to investigate the suitability of the ore to agitation leach processing. Agitation leaching was conducted at pH 2, and the results were subjected to kinetic analyses.

Effects of oils and lubricants on the flotation of copper sulphide minerals

Abstract The effects of the addition of oils and lubricants commonly encountered in mining and processing copper sulphide ores on the subsequent flotation of copper minerals was investigated by laboratory scale testing. The project arose as a result of intermittent uncontrollable frothing and a drop in selectivity observed at an Australian copper-gold concentrator. The addition of distillate to the grinding stage actually increased selectivity in the subsequent copper mineral flotation but other oils and lubricants used at the plant had detrimental effects on selectivity and frothing behaviour. A degreaser used in maintenance operations dramatically lowered copper grade and generated a very stable and sticky froth even at low concentrations. Similar detrimental effects on gold metallurgy were also observed. Mineralogical examination of flotation products verified that the decrease in grade of the concentrates was due to the flotation of free gangue minerals and not due to any liberation problems. Possible mechanisms for these effects aer discussed. Anecdotal evidence for these effects abound in discussions held with plant metallurgists, but little published data on these effects have been located.

Counter-current ion exchange for the removal of organically bound sodium from low-rank coals

Abstract South Australian low-rank coals contain high levels of water-soluble and ion-exchangeable ions that can be deleterious to coal combustion and gasification. The presence of sodium causes the formation of low melting point bonded deposits that can produce severe fouling and slagging in many processes using these coals. Approximately 70% of the sodium present in Bowmans coal is water-soluble and can therefore be removed by simple water leaching, however the remaining 30% is organically bound, predominantly to carboxyl groups. Ion exchange using sulphuric acid at pH 2 is necessary to remove this sodium, but this can generate large volumes of acidic wastewater if multiple washing stages are used with fresh water each time. Using a simple laboratory procedure, the continuous counter-current ion exchange leaching of sodium from this coal was simulated which reduced the sodium level from 1.30% on a dry basis (db) to 0.15% (db) after three stages of counter-current washing at a total coal:water ratio of 1:2. The effectiveness of interstage dewatering on the efficiency of sodium removal was highlighted. The agreement between predicted and measured values of moisture and sodium in coal was excellent.