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Aim: Evaluation of the thermal and physical conditions for inactivation of adenovirus (AdV), porcine sapelovirus 1 (PSV1) and the economically important viruses porcine epidemic diarrhoea virus (PEDV) and porcine circovirus 2 (PCV2) in the production of spray-dried porcine plasma (SDPP). Methods and Results: Citrate-treated porcine plasma of pH 7·5, 9·8 and 10·2 (8·5% dry-matter) was spiked with PEDV, PSV1, PCV2 and AdV and incubated at 3°C for maximum 24 h, and at 44 or 48°C for maximum 10 min (Experiment 1). Spiked citrate-treated concentrated plasma of pH 7·5 and 9·8 (24% dry-matter) was spray dried in a laboratory scale apparatus (Experiment 2). Aliquots of SDPP were stored over a period of 0–10 weeks at 11 and 20°C (Experiment 3). Reverse transcription(RT)-quantitative PCR detected no notable reduction in viral genomes in treated plasma and SDPP samples. No infectious PSV1 was re-isolated from plasma and SDPP samples in cell culture. At pH 10·2 and 3°C, infectivity of PEDV in plasma was reduced with a reduction factor of 4·2 log 10 (LRF) at 10 h contact time, whereas heating to 44°C for at least 1 min at alkali pH was needed to achieve a LRF of 4·2 for AdV. Spray drying at an outlet temperature of 80°C reduced AdV infectivity effectively (LRF = 5·2) and PEDV infectivity for 95% (LRF = 1·4). After storage at 20°C for 2 weeks no infectious PEDV was re-isolated from SDPP anymore (LRF ≥4·0). Due to growth of antibiotic-resistant bacteria from plasma in cell cultures used for PCV2 isolation, no data regarding inactivation of PCV2 were obtained. Conclusions: Five percent of PEDV stayed infectious after our spray drying conditions. Spray drying in combination with storage for ≥2 weeks at 20°C eliminated infectivity of PEDV effectively. Significance and Impact of the Study: The conditions for inactivation of virus in plasma and SDPP determined are important for producers to inactivate PEDV during production of SDPP.

In the ARNi process, up to 95% of the nickel and cobalt are recovered from limonitic nickel laterites by a brine leach at atmospheric pressure, and the leaching and neutralising reagents are then regenerated by decomposition at high temperature. Mass and energy balances were used in the development of the process, together with laboratory studies and pilot-plant testwork. The results of the pilot-plant tests have confirmed the technical feasibility of the process., In the ARNi process, up to 95% of the nickel and cobalt are recovered from limonitic nickel laterites by a brine leach at atmospheric pressure, and the leaching and neutralising reagents are then regenerated by decomposition at high temperature. Mass and energy balances were used in the development of the process, together with laboratory studies and pilot-plant testwork. The results of the pilot-plant tests have confirmed the technical feasibility of the process.

The presence of calcium (Ca) and magnesium (Mg) in the hydrometallurgical processing of base metals results in a number of difficulties. These problems range from the contamination of the final product, to high energy consumption and large bleed streams during electrowinning. Calcium poses a greater problem in sulphate solutions due to the low solubility of its sulphate salts. In the first part of this study, fluoride precipitation of calcium and magnesium is considered for investigation, using a batch precipitation reactor. The batch precipitation reaction investigated the effects of the quantity of fluoride, molar ratio of Ca to Mg, identity of the soluble fluoride and temperature. The possibility of controlling Ca and Mg through the precipitation of their respective fluorides, without the co-precipitation of nickel and cobalt was shown. At Mg to Ca molar ratio above 3, the precipitation of Mg dominated over that of Ca due to the former’s high concentration in the reaction vessel and therefore, its high activity. For a 10% stoichiometric excess amount of fluoride, 96.5% Ca and 98.5% Mg were removed. When the identity of soluble fluoride was considered, results demonstrated that NH4F solution caused a higher Ca and Mg precipitation compared with HF. This was found to be due to the high stability of the HF complex in solution when using HF as the fluoride source, resulting in a lower free fluoride activity in the solution. For the range investigated (45–65 C) temperature was found to have a negligible effect on the precipitation of the alkaline earth metals. The supersaturation ratio for CaF2 was 73 and 27 for MgF2 and it was found that while primary nucleation did not dominate, it could not be ruled out completely. A conceptual process is proposed whereby only a portion of the leach stream is subjected to the fluoride precipitation process, after which it is returned to lower the overall Ca and Mg concentrations. This method is expected to reduce the effect of the

The presence of calcium (Ca) and magnesium (Mg) in the hydrometallurgical processing of base metals is responsible for the contamination of the final product, high energy consumption and large bleed streams during electrowinning. This paper elaborates on the use of ammonium fluoride to precipitate Ca and Mg as their respective fluoride minerals, namely, fluorite and sellaite. The effects of residence time and mixing regimes on crystal growth characteristics and the derived particle size distributions were investigated. The mixing levels in a typical mixed-suspension–mixed-product-removal (MSMPR) were represented by 3 possible mixing regimes; micro-, meso- and macromixing. A three-zone experimentalsetup was used to study the effects of the micro-, meso-, and macromixing on the crystal size distribution and filterability of fluorite and sellaite. The ionic strength of the sulphate solutions used was similar to those found in base metal leach circuits. As a result, SEM-images of the formed crystals depicted stable agglomerates of around 20 µm consisting of smaller particles in the range of 1–3 µm. The filter cake resistance was found to be around 4.0×109 m3/kg m2, and did not vary significantly for the experimental conditions chosen for the 3-zone experiment. The residence time did have a small but significant effect on increasing the mean and median of the particles size distributions. Increase in both macromixing and micromixing resulted in a decrease of the mean particle size, while no significant difference was noticed for mesomixing of the reactant streams. © 2008 Published by Elsevier B.V.

Bidentate 5,5'-alkyl-3,3'-bi-1H-pyrazole and 2-(5-alkyl-1H-pyrazol-3-yl)pyridine ligands, L5 and L6, have been shown to be stronger synergists for the solvent extraction of Ni(II) from sulphate solutions by dinonylnaphthalene sulphonic acid (DNNSAH) than the structurally related tridentate ligand 2,6-bis-[5-n-nonylpyrazol-3-yl]pyridine, L1, previously reported by Zhou and Pesic. The bidentate ligands are highly selective, providing the option of sequential recovery of Ni(II) and Co(II) and rejection of other metals commonly found in the liquors resulting from the acidic sulphate leaching of laterite ores. They were the strongest synergists identified in a screening carried out on 18 types of bidentate and tridentate N-heterocyclic ligands, including the recently reported 2-(2'-pyridyl)imidazoles, L9-11. X-ray crystal structures of Ni(II) complexes of model ligands for L5 and L6, having t-butyl rather than long-chain alkyl groups and with 2-naphthalene sulphonate rather than DNNSA- as counteranions, show that the [Ni(L)3]2+ complexes form strong H-bonds from the pyrazolyl NH groups to the oxygen atoms of the sulphonate groups, an arrangement that will stabilise [Ni(L)3·(DNNSA)2] assemblies and shield their polar functionalities from diluent molecules of the water-immiscible phase. UV-visible spectra and mass spectrometry provide evidence for the strong synergists displacing all water molecules from the inner coordination sphere of the Ni(II) ions. (Authors.), Bidentate 5,5'-alkyl-3,3'-bi-1H-pyrazole and 2-(5-alkyl-1H-pyrazol-3-yl)pyridine ligands, L5 and L6, have been shown to be stronger synergists for the solvent extraction of Ni(II) from sulphate solutions by dinonylnaphthalene sulphonic acid (DNNSAH) than the structurally related tridentate ligand 2,6-bis-[5-n-nonylpyrazol-3-yl]pyridine, L1, previously reported by Zhou and Pesic. The bidentate ligands are highly selective, providing the option of sequential recovery of Ni(II) and Co(II) and rejection of other metals commonly found in the liquors resulting from the acidic sulphate leaching of laterite ores. They were the strongest synergists identified in a screening carried out on 18 types of bidentate and tridentate N-heterocyclic ligands, including the recently reported 2-(2'-pyridyl)imidazoles, L9-11. X-ray crystal structures of Ni(II) complexes of model ligands for L5 and L6, having t-butyl rather than long-chain alkyl groups and with 2-naphthalene sulphonate rather than DNNSA- as counteranions, show that the [Ni(L)3]2+ complexes form strong H-bonds from the pyrazolyl NH groups to the oxygen atoms of the sulphonate groups, an arrangement that will stabilise [Ni(L)3·(DNNSA)2] assemblies and shield their polar functionalities from diluent molecules of the water-immiscible phase. UV-visible spectra and mass spectrometry provide evidence for the strong synergists displacing all water molecules from the inner coordination sphere of the Ni(II) ions. (Authors.)