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Kesieme U.K.,CSIRO | Kesieme U.K.,Victoria University of Melbourne | Aral H.,CSIRO | Aral H.,Jervois Mining Ltd
Journal of Environmental Chemical Engineering | Year: 2015

Direct contact membrane distillation (DCMD) and solvent extraction (SX) were tested in series to recover water and acid from acidic mining waste solutions. In the DCMD step with the synthetic acidic waste solution, the concentration of H2SO4 increased from 0.85 M in the feed solution to 4.44 M in the concentrate. Sulphate and metal separation efficiency was >99.99% and the overall water recovery exceeded 80%. After recovery of water with DCMD, the concentrated solution was then subjected to recovery of sulphuric acid using SX with an organic system consisting of 50% TEHA and 10% ShellSol A150 in octanol. Over 80% H2SO4 was extracted in a single contact from the waste solution containing 245 g/L H2SO4 and metals with various concentrations. After three stages of successive extraction, nearly 99% of acid was extracted, leaving only 2.4 g/L H2SO4 in the raffinate. The extracted acid was stripped readily from the loaded organic solution using water at 60°C. After scrubbing the loaded organic solution at an O/A ratio of 10 and 22°C, 98-100% of entrained metals were removed in a single contact with only 4.5% acid lost in the loaded scrub liquor. It was found that the phase disengagement time was in the range of 2-4 min for both extraction and stripping, indicating reasonable fast phase separation. © 2015 Elsevier Ltd. All rights reserved. Source


Kesieme U.K.,CSIRO | Kesieme U.K.,Victoria University of Melbourne | Aral H.,Victoria University of Melbourne | Aral H.,Jervois Mining Ltd | And 3 more authors.
Hydrometallurgy | Year: 2013

TEHA (tris-2-ethylhexylamine) was selected as the extractant in the current study due to high acid extraction and ease in stripping. An optimum organic system consisting of 50% TEHA, 40% octanol and 10% Shellsol A150 was determined. It was found that the acid extraction decreased with the increase in temperature. The change in enthalpy (ΔH) was - 13.2 kJ mol- 1, indicating exothermic extraction reaction. Both extraction and stripping kinetics was very fast. McCabe-Thiele extraction diagram showed that for a feed solution containing 200 g/L H2SO4, three stages are required. McCabe-Thiele stripping diagram showed that three stages are required. Using slope analysis, it was found that the extracted species consisted of one acid molecule, one TEHA (A) molecule and two octanol (O) molecules with a formulae of H2SO4AO2̄. The optimised TEHA system was used to extracted acid from a synthetic process solution containing a number of metals. It was found that the system only extracted acid with a small amount of metals entrained. After scrubbing the loaded organic solution in a single contact, almost all entrained metals were removed. In the case that the mining waste solution contains low concentration of acid, membrane distillation (MD) technology can be used to recover the water and concentrate the acid and metals. Solvent extraction can be then used to recover the acid and metals. A conceptual process flowsheet has been developed using a combination of MD and SX. © 2013 Published by Elsevier B.V. All rights reserved. Source


Kesieme U.K.,Victoria University of Melbourne | Kesieme U.K.,CSIRO | Milne N.,Victoria University of Melbourne | Cheng C.Y.,CSIRO | And 3 more authors.
Water Science and Technology | Year: 2014

This paper describes for the first time the use of direct contact membrane distillation (DCMD) for acid and water recovery from a real leach solution generated by a hydrometallurgical plant. The leach solutions considered contained H2SO4 or HCl. In all tests the temperature of the feed solution was kept at 60 °C. The test work showed that fluxes were within the range of 18-33 kg/m2/h and 15- 35 kg/m2/h for the H2SO4 and HCl systems, respectively. In the H 2SO4 leach system, the final concentration of free acid in the sample solution increased on the concentrate side of the DCMD system from 1.04 M up to 4.60 M. The sulfate separation efficiency was over 99.9% and overall water recovery exceeded 80%. In the HCl leach system, HCl vapour passed through the membrane from the feed side to the permeate. The concentration of HCl captured in the permeate was about 1.10 M leaving behind only 0.41 M in the feed from the initial concentration of 2.13 M. In all the experiments, salt rejection was > 99.9%. DCMD is clearly viable for high recovery of high quality water and concentrated H2SO4 from spent sulfuric acid leach solution where solvent extraction could then be applied to recover the sulfuric acid and metals. While HCl can be recovered for reuse using only DCMD. © IWA Publishing 2014. Source


Kesieme U.K.,Victoria University of Melbourne | Kesieme U.K.,CSIRO | Milne N.,Victoria University of Melbourne | Aral H.,Victoria University of Melbourne | And 3 more authors.
Desalination | Year: 2013

The economics of membrane distillation (MD) and common seawater desalination methods including multi effect distillation (MED), multistage flash (MSF) and reverse osmosis (RO) are compared. MD also has the opportunity to enhance RO recovery, demonstrated experimentally on RO concentrate from groundwater. MD concentrated RO brine to 361,000mg/L total dissolved solids, an order of magnitude more saline than typical seawater, validating this potential. On a reference 30,000m3/day plant, MD has similar economics with other thermal desalination techniques, but RO is more cost effective. With the inclusion of a carbon tax of $23 per tonne carbon in Australia, RO remained the economically favourable process. However, when heat comes at a cost equivalent of 10% of the value of the steam needed for MD and MED, under a carbon tax regime, the cost of MD reduces to $0.66/m3 which is cheaper than RO and MED. The favour to MD was due to lower material cost. On low thermally, high electrically efficient installations MD can desalinate water from low temperature (<50°C) heat sources at a cost of $0.57/m3. Our assessment has found that generally, MD opportunities occur when heat is available at low cost, while extended recovery of RO brine is also viable. © 2013 Elsevier B.V. Source


Pownceby M.I.,CSIRO | Sparrow G.J.,CSIRO | Aral H.,CSIRO | Aral H.,Jervois Mining Ltd | And 3 more authors.
Transactions of the Institutions of Mining and Metallurgy, Section C: Mineral Processing and Extractive Metallurgy | Year: 2015

Mineral sand deposits in the Murray Basin offer the potential for significantly expanding Australia's production of ilmenite, rutile and zircon. Since prices of zircon and rutile are higher than ilmenite, and zircon grades in most deposits are significantly higher than those for rutile, zircon often is the major economic mineral component in mineral sand deposits. Two types of deposits occur in the Murray Basin. They comprise strandline deposits, in which the particle size of the heavy minerals is similar to that in other Australian deposits, and fine grained, sheet-like, WIM style deposits. While production from several strandline deposits has commenced, the fine grained deposits, which contain significantly greater amounts of mineralisation, are still to be developed. Problems with processing the finer particle size of the mineralisation, its variable mineralogy, higher surface and lattice impurity levels, in particular uranium and thorium in zircon grains, have contributed to this. Overcoming these problems is necessary to obtain the full commercial value from the Murray Basin deposits. Processing to recover a fine grained zircon concentrate from the extensive WIM style deposits and the removal of impurities in the concentrate are discussed in this paper. In particular, treatments to remove surface and lattice impurities, and to lower uranium and thorium levels by an acid leach and with heat and leach treatments, are reviewed. The conditions used in the heating treatment (e.g. Temperature and nature of any fluxes added) affect the impurity removal and whether zirconia (ZrO2) or zircon (ZrSiO4) is obtained as the product. © 2015 Institute of Materials. Source

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