Status Report of the DPHEP Study Group: Towards a Global Effort for Sustainable Data Preservation in High Energy Physics

Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. An inter-experimental study group on HEP data preservation and long-term analysis was convened as a panel of the International Committee for Future Accelerators (ICFA). The group was formed by large collider-based experiments and investigated the technical and organisational aspects of HEP data preservation. An intermediate report was released in November 2009 addressing the general issues of data preservation in HEP. This paper includes and extends the intermediate report. It provides an analysis of the research case for data preservation and a detailed description of the various projects at experiment, laboratory and international levels. In addition, the paper provides a concrete proposal for an international organisation in charge of the data management and policies in high-energy physics

Iron and sulfur utilisation patterns in chemolithotrophic cultures

In this study, the growth and behaviour of chemolithotrophic organisms in the presence of both ferrous and tetrathionate ions was investigated. Given the impact of chemolithotrophic metabolic activity upon the chemistry and leaching of mineral sulfide systems, investigations were conducted to determine the effects of solution variables on substrate utilisation. A set of eight organisms, capable of oxidising ferrous ions or reduced sulfur compounds, were adapted to ferrous or tetrathionate ions. These cell lines were cultured in media containing 2.5 mM of tetrathionate, with either high or low concentrations of ferrous ions present. Sb.xthermosulfidooxidans and M. hakonensis grew in a diauxic growth pattern utilising ferrous ions preferentially, irrespective of adaptive history or ferrous concentration. At. ferrooxidans, Sb. acidophilus, Sb.xsibiricus, Sb. thermotolerans, A.xbrierleyi and S. metallicus exhibited simultaneous substrate utilisation and a single phase of growth under at least one of the four conditions tested. Preferential utilisation of tetrathionate was not observed under any of the four conditions tested. Planktonic cell numbers were not consistently proportional to the total quantity of the reduced substrate(s) oxidised. Reduced sulfur species were detected during batch culture growth of At. caldus on tetrathionate. Formation of elemental sulfur, thiosulfate, sulfite, penta- and hexathionate were consistent with the enzymatic hydrolysis of tetrathionate and subsequent chemical reactions. Growth yields were comparatively low with an average value of 3.53 g(dry wt.) mol(S4O6)-1. However, a significant quantity of reduced organic material was detected dissolved in solution. Yield data obtained from this study was compared with other reports and analysed using a thermodynamic framework derived from studies of heterotrophic growth. This analysis indicated that the conserved substrate had a sulfur(IV) atom oxidised to sulfur(VI). The addition of nitrate significantly modified substrate oxidation patterns in a growth medium containing ferrous and tetrathionate ions. Ferrous ion oxidation processes were inhibited to a greater extent than tetrathionate utilisation. Tetrathionate-adapted cultures of Sb. acidophilus and Sb. sibiricus demonstrated preferential oxidation of tetrathionate at nitrate concentrations of 20–40 mM. Iron-adapted cultures of M.xhakonensis preferentially oxidised ferrous ions in the presence of nitrate at all concentrations where growth was observed. Responses of other test species varied, depending on the nitrate concentration and adaptive history of the organism. Nitrate was added to control the redox potential of the solution in cultures bioleaching chalcopyrite. Redox potentials were not controlled at 30 and 45 °C. Copper extraction was equal to, or less than that seen in cultures without nitrate present. The addition of nitrate to cultures at 60 °C maintained the redox potential between 430–460 mV (Ag/AgCl). Copper extraction in these systems was increased compared with cultures where nitrate was absent

Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II) and/or reduced inorganic sulphur compounds (RISC), such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As) to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity

Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II) and/or reduced inorganic sulphur compounds (RISC), such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As) to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity

Effects of pH, temperature and solids loading on microbial community structure during batch culture on a polymetallic ore

The bioleaching of an organic-rich polymetallic ore was conducted under conditions intended to probe the boundaries of microbial activity using iron and sulphur oxidising microorganisms and heterotrophs enriched from self-heating pyritic coal. Solution chemistry parameters such as rapidly increased ORP and reduction in pH subsequent to inoculation point to the development of active microbial communities. The ease with which communities adapted to the organic-rich ore and the bioleaching systems indicated that the organic compounds were not present in leachates at toxic levels. Overall, extractions obtained in three series of inoculated tests were at 35 °C: 79–96% Zn, 48–82% Cu, 47–55% Ni and 79–86% Co; at 55 °C: 96–97% Zn, 72–80% Cu, 46–50% Ni and 82–83% Co. T-RFLP provided semi-quantitative estimates of species abundance. The greatest microbial complexity was observed with moderate pH and low solids loading. Microbial complexity was reduced significantly by low pH or increased solids loading. Nevertheless, efficient bioleaching was observed over a relatively wide range of operating conditions. Even under the more extreme conditions, the community profile was dominated by combinations of organisms not typically seen in most commercial operations

Synthesis of a <i>t</i>-α-Hydroxy Oxime and its Synergistic Behavior with Versatic 10

<div><p>The aliphatic α-hydroxyoxime LIX^® 63 contains a secondary hydroxyl group that is susceptible to oxidation. In the present work, an alternative oxidation-resistant α-hydroxyoxime containing a tertiary hydroxyl group, namely (1-hydroxycyclohexyl)-phenyl ketone oxime (“phenyl oxime”), has been synthesized and characterized. Combining phenyl oxime with Versatic 10 results in synergistic metal extraction behavior. The ability of this ligand to withstand oxidation is demonstrated. Other benefits are also evident, including its existing wholly in the active <i>anti</i> isomeric form and exhibiting fast nickel kinetics in the synergistic system. Phenyl oxime readily undergoes aqueous acid-catalyzed hydrolysis and so is not commercially practical. Addition of carbon side-chains could help to overcome this.</p></div

Characterization and Inhibition of a Nickel-Alpha-Hydroxyoxime (LIX 63) Salt Precipitate Formed under Proposed Commercial Operating Conditions

As a prospective commercial solvent extraction (SX) process, laboratory-scale continuous tests were recently undertaken to assess the use of a solution of LIX 63 hydroxyoxime (“hydroxyoxime”) and Versatic 10 to kinetically separate cobalt from a nickel-rich sulfate solution while simultaneously rejecting manganese and magnesium. A material quantity of blue precipitate observed in the strip stage cells during decommissioning has been identified as the sulfate salt of the nickel-tris hydroxyoxime complex. As precipitation during SX is undesirable, the effect of various operating parameters on precipitate formation has been investigated. Minimizing aqueous nickel and/or sulfuric acid concentration and/or increasing organic polarity can overcome this problem. Where it forms, hydroxyoxime and nickel can be recovered from the precipitate by redissolution under suitable (e.g., low acid) operating conditions. The nitrate salt counterpart of this sulfate precipitate has been crystallographically characterized using a short chained (C₈) analogue of LIX 63 hydroxyoxime, revealing the coordination of three neutral hydroxyoxime ligands around nickel, forming a monomeric coordination complex cation counterbalanced by nitrate anions

Characterization and Inhibition of a Nickel-Alpha-Hydroxyoxime (LIX 63) Salt Precipitate Formed under Proposed Commercial Operating Conditions

As a prospective commercial solvent extraction (SX) process, laboratory-scale continuous tests were recently undertaken to assess the use of a solution of LIX 63 hydroxyoxime (“hydroxyoxime”) and Versatic 10 to kinetically separate cobalt from a nickel-rich sulfate solution while simultaneously rejecting manganese and magnesium. A material quantity of blue precipitate observed in the strip stage cells during decommissioning has been identified as the sulfate salt of the nickel-trishydroxyoxime complex. As precipitation during SX is undesirable, the effect of various operating parameters on precipitate formation has been investigated. Minimizing aqueous nickel and/or sulfuric acid concentration and/or increasing organic polarity can overcome this problem. Where it forms, hydroxyoxime and nickel can be recovered from the precipitate by redissolution under suitable (e.g., low acid) operating conditions. The nitrate salt counterpart of this sulfate precipitate has beencrystallographically characterized using a short chained (C8) analogue of LIX 63 hydroxyoxime, revealing the coordination of three neutral hydroxyoxime ligands around nickel, forming a monomeric coordination complex cation counterbalanced by nitrate anions