Bio-reduction of sulfide minerals to recover invisible gold

Sulfide minerals, like pyrite and arsenopyrite, are of economical interest due to the presence of invisible gold locked inside these minerals. As fine grinding is often not sufficient to liberate the gold from these minerals, additional destruction techniques, based on chemical and biological oxidation processes, are required to access the gold via cyanidation. These techniques have proven to be successful to reach satisfactory gold recoveries, but operation costs are high and challenging waste streams (sulfuric acid) are produced. As an alternative to the oxidation methods in this thesis the bio-reduction of sulfide minerals was proposed and investigated. Bio-reduction, the use of hydrogen to convert mineral-sulfur to hydrogen sulfide, has as major advantage that the hydrogen sulfide can be recovered from the solution (to produce bio-sulfur) leaving a waste stream without diluted sulfuric acid. Furthermore, electrical energy will be saved. Theoretically, this more environmental friendly alternative should work, but no bio-reduction reaction was observed in practice. It appeared that sulfur/sulfate reducing bacteria were not able to use sulfur when fixed in the crystal lattice of pyrite and arsenopyriteat the selected conditions (pH 5, 35ºC). In order to make the mineral-sulfur bio-available for these bacteria the sulfur should first enter the solution. As alternative the combination between partial bio-oxidation and bio-reduction was therefore investigated. Partial bio-oxidation at pH 2 results in the formation of elemental sulfur, which can serve as a substrate at pH 5 for the sulfur/sulfate reducing bacteria. This combined method was found to be successful at 35°C, as the gold leachability of the used concentrate was increased from 6% to 39%. Optimization of this process is needed to reach gold recoveries >90% in 1 or 2 ox/red cycles, but when successful a new method (called the Paroxsul process) with a lower environmental impact, less costs, and application to a large number of minerals, is ready to be introduced to the precious metal industry. </p

Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij: indicatieve evaluatie van biofiltratie als potentiële fijnstofreductietechniek = Measures to reduce fine dust emission from poultry: indicative evaluation of biofiltration as potential fine dust reduction technique

In this study biofiltration is indicatively evaluated for its potential to remove fine dust from exhaust air of poultry houses. From this study it is concluded that biofiltration can be effective and applicable

Onderzoek naar de ammoniak- en geuremissie van stallen LVI : scharrelstal voor leghennen met frequente mest- en strooiselverwijdering = Free range housing system for laying hens with frequent manure and litter removal

Door IMAG werd onderzoek verricht naar de ammoniak- en geuremissie van een scharrelstal voor leghennen met volledige ontmesting. Het ammoniakemissiereducerend principe berustte op het eenmaal per week verwijderen van de mest onder de beun en het strooisel in de stal. Hiervoor werden met behulp van een speciaal ontworpen machine de twee componenten via een vijzel op een transportband gebracht en uit de stal verwijderd. Na afvoer werd met dezelfde machine een nieuwe laag zaagsel (strooisel) in de scharrelruimte gebracht

Onderzoek naar de ammoniak- en geuremissie van stallen LIV : stal voor vleeskuikenouderdieren met continue drogen van mest = Housing system for broiler breeders with continuous drying of manure

Door IMAG werd nderzoek verricht naar de ammoniak- en geuremissie van twee afdelingen in een traditionele stal voor vleeskuikenouderdieren. Beide afdelingen waren uitgerust met een traditioneel huisvestingssysteem voor vleeskuikenouderdieren. Eén van beide was daarnaast voorzien van een systeem voor het continue drogen van de mest onder de beun met opgewarmde buitenlucht. De opgewarmde buitenlucht werd met een luchtverdeelsysteem door de mest geblazen. De andere afdeling diende als referentie

Dementia in Parkinson's Disease Correlates with α-Synuclein Pathology but Not with Cortical Astrogliosis

Dementia is a common feature in Parkinson's disease (PD) and is considered to be the result of limbic and cortical Lewy bodies and/or Alzheimer changes. Astrogliosis may also affect the development of dementia, since it correlates well with declining cognition in Alzheimer patients. Thus, we determined whether cortical astrogliosis occurs in PD, whether it is related to dementia, and whether this is reflected by the presence of glial fibrillary acidic protein (GFAP) and vimentin in cerebrospinal fluid (CSF). We have examined these proteins by immunohistochemistry in the frontal cortex and by Western blot in CSF of cases with PD, PD with dementia (PDD), dementia with Lewy bodies (DLB) and nondemented controls. We were neither able to detect an increase in cortical astrogliosis in PD, PDD, or DLB nor could we observe a correlation between the extent of astrogliosis and the degree of dementia. The levels of GFAP and vimentin in CSF did not correlate to the extent of astrogliosis or dementia. We did confirm the previously identified positive correlation between the presence of cortical Lewy bodies and dementia in PD. In conclusion, we have shown that cortical astrogliosis is not associated with the cognitive decline in Lewy body-related dementia

Fijnstofemissie uit stallen: leghennen in volièrehuisvesting = Dust emission from animal houses: layer hens in aviary systems

In this study emissions of fine dust (PM10 and PM2.5) from houses for layer hens in aviary systems were determined. In addition, emissions of ammonia, greenhouse gases and odour were determine

Characteristics and outcomes of patients requiring rapid response system activation within 24 hours of emergency admission

Objectives:&nbsp;To establish the prevalence of emergency responses for clinical deterioration (cardiac arrest team or medical emergency team [MET] activation) within 24 hours of emergency admission, and determine if there were differences in characteristics and outcomes of ward patients whose emergency response was within, or beyond, 24 hours of emergency admission. Design, setting and participants: A retrospective, descriptive, exploratory study using MET, cardiac arrest, emergency department and inpatient databases, set in a 365-bed urban district hospital in Melbourne, Australia. Participants were adult hospital inpatients admitted to a medical or surgical ward via the emergency department (ED) who needed an emergency response for clinical deterioration during 2012. Main outcome measures: Inhospital mortality, unplanned intensive care unit admission and hospital length of stay (LOS). Results: A total of 819 patients needed an emergency response for clinical deterioration: 587 patients were admitted via the ED and 28.4% of emergency responses occurred within 24 hours of emergency admission. Patients whose first emergency response was within 24 hours of emergency admission (compared with beyond 24 hours) were more likely to be triaged to Australasian triage scale category 1 (5.4% v 1.2%, P=0.005), less likely to require ICU admission after the emergency response (7.6% v 13.9%, P=0.039), less likely to have recurrent emergency responses during their hospital stay (9.7% v 34%, P &lt; 0.001) and had a shorter median hospital LOS (7 days v 11 days, P &lt; 0.001). Conclusions: One-quarter of emergency responses after admission via the ED occurred within 24 hours. Further research is needed to understand the predictors of deterioration in patients needing emergency admission.</div

Fijnstofemissie uit stallen: dragende zeugen = Dust emission from animal houses: pregnant sows

In this study emissions of fine dust (PM10 and PM2.5) from houses for pregnant sows were determined. In addition, emissions of ammonia, greenhouse gases and odour were determined

Fijnstofemissie uit stallen: vleesvarkens = Dust emission from animal houses: growing and finishing pigs

In this study emissions of fine dust (PM10 and PM2.5) from houses for growing-finishing pigs were determined. In addition, emissions of ammonia, greenhouse gases and odour were determined

Onderzoek naar de ammoniak- en geuremissie van stallen LX : stal voor voedsters en vleeskonijnen

Ammonia emission from animal husbandry has to be reduced in the Netherlands by 70% in the year 2005, compared with the emission level in 1980. Moreover, new odour legislation requires measurements of the odour emissions of the main conventional and newly developed housing systems. Research was carried out into the emission of ammonia and odour from a mechanically ventilated housing system for does and fattening rabbits. The rabbits were housed in wire gauze cages. The manure was collected on a roughly woven transport belt. The manure was removed regularly. Urine could leach through cracks in the belt to a urine pit