Arsenic behavior during the treatment of refractory gold ores via POX: Characterization of Fe-AsO4-SO4 precipitates

Abstract Arsenic is a common contaminant in refractory gold ores/concentrates and it's accepted that total pressure oxidation (POX) is the most appropriate technology to treat these due to their refractoriness and ability to stabilize arsenic via ferric arsenate compounds (Fe-As). However, information gaps about the behavior and stability of the various Fe-As's formed at high temperatures in downstream gold processing steps remain and may have significant practical implications. This paper focuses on the precipitation behavior of arsenic during autoclaving of various arsenopyrite containing ore concentrates from around the world. The first portion involved the precipitation of different synthetic precipitates at POX conditions found in the gold industry by varying Fe/As ratios in the feed solutions. Mineralogical characterization results showed that arsenate-containing basic ferric sulphate (As-BFS), basic ferric arsenate sulphate (BFAS), and ferric arsenate sub-hydrate (FAsH) formed. In the second portion, five pyrite/arsenopyrite concentrates received from gold mines around the world were submitted to batch POX and mineralogical analysis. We observed that the mechanism of precipitation for pyrite/arsenopyrite concentrates appears to be different vs. synthetic solutions. Upon processing of the gold concentrates under POX, the initial Fe/As ratio in the concentrates was retained to the final generated residues. The major Fe-As's generated in the POX residues from the concentrates were As-BFS and BFAS, while non-As containing ferric phases included hematite and some small fraction of jarosite. Finally, we observed that as the Fe/As molar ratio in the concentrate feed increased, the amount of As-BFS decreased while that of BFAS increased

Intestinal transplantation in children: A summary of clinical outcomes and prognostic factors in 108 patients from a single center

We performed 124 intestinal transplants on 108 children (median age, 1.5 years) since 1994. Initial graft types included isolated intestine (I) (n = 26), liver and intestine (LI) (n = 26), multivisceral (MV) (n = 50), and multivisceral without liver (MMV) (n = 6). Four groups were defined by type of induction therapy: none, OKT3, or cyclophosphamide (August 1994-December 1997, n = 25), early experience with daclizumab (January 1998-December 2000, n = 26), recent experience with daclizumab (January 2001–April 2004, n = 40), and Campath-1H (January 2001-April 2004, n = 17). Actuarial patient survival at 1 year for groups 1–4 was 44% ± 10%, 54% ± 10%, 83% ± 6%, and 41% ± 12%, respectively, with group 3 having the most favorable survival (P = 0.0004). Using Cox stepwise regression, the hazard rate of developing severe rejection was significantly higher in patients with transplant type I or LI (P = 0.0002), with no difference between these groups (P = 0.24) but a significantly higher rate for LI versus MV (P = 0.005). Three factors associated with improved patient survival were recipient of MV or MMV (P = 0.008), age at transplantation greater than 1 year (P = 0.01), and use of daclizumab (P = 0.0006). Cause-specific hazard analysis revealed a decreased rate of rejection-related mortality for recipients of MV or MMV (P = 0.0007), whereas age greater than 1 year indicated a lower rate of infection-related mortality (P = 0.0009). Pediatric intestinal transplantation provides an increasingly realistic chance of survival, particularly with the more recent use of daclizumab and multivisceral transplantation. A protective effect of multivisceral transplantation appears to exist with respect to the development of severe rejection

A "Boxer Glove" Contoured Laryngeal Amyloidosis

Laryngeal amyloidosis is uncommon and poorly understood, with limited long-term studies. Although primary localized laryngeal amyloidosis is extremely rare, it frequently involves the ventricles and the false and true vocal cords. We present a 58-year-old woman with localized laryngeal amyloidosis who presented no symptoms. On indirect laryngoscopic examination, the mass involved both arytenoids only, and had a likeness to a "boxer glove." She was treated surgically by microlaryngoscopy under general anesthesia and the mass was excised using a carbon dioxide laser. We present this case and a review of literature

Comparative outcomes of extracorporeal membrane oxygenation for COVID-19 delivered in experienced European centres during successive SARS-CoV-2 variant outbreaksan international multicentre retrospective cohort study

International audienc

Comparative outcomes of extracorporeal membrane oxygenation for COVID-19 delivered in experienced European centres during successive SARS-CoV-2 variant outbreaksan international multicentre retrospective cohort study

International audienc