Electrokinetic properties of wavellite and its floatability with cationic and anionic collectors

AbstractThe reverse apatite flotation with fatty acids has been widely used for the reduction of phosphorus content of magmatic origin iron ores. However, the occurrence of phosphorus intensely disseminated as secondary minerals such as wavellite renders the anionic reverse flotation a challenge. Zeta potential measurements and microflotation tests of wavellite with the use of anionic and cationic collectors were carried out in this work. The wavellite’s IEP value was achieved at pH 4.5. Below the IEP value, the surface positively charged sites are made up of aluminum ions. The species H+,Al(OH)2+,Al(OH)2+,Al3+,OH-,H2PO4-,HPO42-, and PO43- play a role in the protonation and deprotonation reactions that will determine the wavellite-solution interface properties. The highest values of wavellite’s floatability under basic pH conditions were achieved in the presence of cationic collectors (1×10−4molL−1). The formation of surface complexes and the precipitation of insoluble salt of aluminum onto wavellite surface seems to be the most likely hypothesis for the chemical nature interactions between amines and wavellite. The surface formation of aluminum oleate on the wavellite’s surface seems to be the most probable hypothesis for the adsorption mechanism and the resultant high floatability of wavellite between pH 7.5 and pH 10.0 in the presence of sodium oleate (1×10−4molL−1). The results showed that the cationic reverse flotation of secondary phosphates is a promising route to reduce the phosphorus content of iron ores from deposits that underwent a supergene enrichment process, since wavellite floatability in the alkaline pH range, using amine as collector, was not significantly affected by the presence of corn starch

OBTENÇÃO DE PASTAS MINERAIS A PARTIR DO ESPESSAMENTO DE LAMAS PROVENIENTES DE PROCESSAMENTO FOSFÁTICO

Os minérios atualmente lavrados têm apresentado teores cada vez menores, impactando no aumento da produção de rejeitos e necessitando de técnicas para viabilizar sua disposição a seco. Entre essas técnicas, espessamento e processos de agregação de partículas, como a floculação, são utilizados para a produção de líquidos clarificados e de pastas minerais. Devido à menor quantidade de água, as pastas apresentam inúmeras vantagens ambientais e tecnológicas, sendo  necessário considerar previamente suas propriedades reológicas, entre elas a altura de abatimento. O presente estudo objetivou caracterizar as pastas minerais obtidas a partir do espessamento de lamas, quanto ao seu abatimento, e selecionar a dosagem de floculante que apresente as melhores respostas de sedimentação e clarificação dos líquidos sobrenadantes. Os resultados foram obtidos através de ensaios de sedimentação descontínua em proveta, com floculante catiônico e aniônico, apresentando como única variável operacional a dosagem de floculante. Os líquidos clarificados obtidos em cada ensaio tiveram sua turbidez determinada por turbidímetro digital. No que se refere aos parâmetros reológicos, testes slump foram utilizados para determinação da consistência das pastas minerais, em ampla faixa de concentração de sólidos. Resultados mostraram que o floculante catiônico apresentou melhor resposta de sedimentação e clarificação de sobrenadante, cuja velocidade de sedimentação e turbidez foram, respectivamente, 2,40cm/s e 9,4NTU. Para pastas com mais de 80% de sólidos, não foi observado abatimento significativo, próximo a 0,3cm, ao passo que, para polpas diluídas, as mesmas se espalhavam totalmente pela superfície

Correction to: Comparative effectiveness and safety of non-vitamin K antagonists for atrial fibrillation in clinical practice: GLORIA-AF Registry

International audienceIn this article, the name of the GLORIA-AF investigator Anastasios Kollias was given incorrectly as Athanasios Kollias in the Acknowledgements. The original article has been corrected

Patterns of oral anticoagulant use and outcomes in Asian patients with atrial fibrillation: a post-hoc analysis from the GLORIA-AF Registry

Background: Previous studies suggested potential ethnic differences in the management and outcomes of atrial fibrillation (AF). We aim to analyse oral anticoagulant (OAC) prescription, discontinuation, and risk of adverse outcomes in Asian patients with AF, using data from a global prospective cohort study. Methods: From the GLORIA-AF Registry Phase II-III (November 2011-December 2014 for Phase II, and January 2014-December 2016 for Phase III), we analysed patients according to their self-reported ethnicity (Asian vs. non-Asian), as well as according to Asian subgroups (Chinese, Japanese, Korean and other Asian). Logistic regression was used to analyse OAC prescription, while the risk of OAC discontinuation and adverse outcomes were analysed through Cox-regression model. Our primary outcome was the composite of all-cause death and major adverse cardiovascular events (MACE). The original studies were registered with ClinicalTrials.gov, NCT01468701, NCT01671007, and NCT01937377. Findings: 34,421 patients were included (70.0 ± 10.5 years, 45.1% females, 6900 (20.0%) Asian: 3829 (55.5%) Chinese, 814 (11.8%) Japanese, 1964 (28.5%) Korean and 293 (4.2%) other Asian). Most of the Asian patients were recruited in Asia (n = 6701, 97.1%), while non-Asian patients were mainly recruited in Europe (n = 15,449, 56.1%) and North America (n = 8378, 30.4%). Compared to non-Asian individuals, prescription of OAC and non-vitamin K antagonist oral anticoagulant (NOAC) was lower in Asian patients (Odds Ratio [OR] and 95% Confidence Intervals (CI): 0.23 [0.22-0.25] and 0.66 [0.61-0.71], respectively), but higher in the Japanese subgroup. Asian ethnicity was also associated with higher risk of OAC discontinuation (Hazard Ratio [HR] and [95% CI]: 1.79 [1.67-1.92]), and lower risk of the primary composite outcome (HR [95% CI]: 0.86 [0.76-0.96]). Among the exploratory secondary outcomes, Asian ethnicity was associated with higher risks of thromboembolism and intracranial haemorrhage, and lower risk of major bleeding. Interpretation: Our results showed that Asian patients with AF showed suboptimal thromboembolic risk management and a specific risk profile of adverse outcomes; these differences may also reflect differences in country-specific factors. Ensuring integrated and appropriate treatment of these patients is crucial to improve their prognosis. Funding: The GLORIA-AF Registry was funded by Boehringer Ingelheim GmbH