Search Results (4)

In this study, the catalytic air oxidation method was used to selectively form sodium antimonate from an antimony residue Na₂S-NaOH leaching solution of a high arsenic copper anode slime. In the first stage, the leaching process with Na₂S and NaOH media resulted in more than 98% leaching of antimony. The synergistic oxidation method was used to selectively separate antimony in the second stage. In this study, the oxidation rate of antimony was greater than 98% at the NaOH concentration of 50 g·L⁻¹ and a combined oxidation concentration of 0.75 g·L⁻¹ catechol + 0.75 g·L⁻¹ KMnO₄, under the air flow rates of 1.415 m³·min⁻¹ at 75 °C for 8 h. The pH of the crude sodium antimonate product was adjusted; subsequently, it was redissolved and precipitated to prepare refined sodium antimonate that meets the secondary product standard of China’s non-ferrous metal industry, which recommends an antimony recovery rate of >95.60%. After neutralisation, the liquid contains [As] < 0.10 g·L⁻¹, [Sb] = 0.16–0.38 g·L⁻¹, which can be reused in the composite leaching process. The apparent activation energy (Ea) of the catalytic oxidation reaction was 6.47 kJ·mol⁻¹; the results suggested that the reaction process was diffusion controlled. $-\frac{d\left[Sb\right]}{dt}=8.86\times {10}^{-5}\times e^{\frac{-778.44}{T}}\times {\left[Sb\right]}^{0.4906}\times {\left[NaOH\right]}^{1.190}$. Full article

The efficient separation of antimonate minerals from quartz remains a significant challenge in mineral processing due to their similar surface properties and strong hydrophilicity. This study explored the application of sodium dodecyl sulfonate (SDS) as a selective collector for antimonate–quartz flotation separation. Micro-flotation tests demonstrated that SDS achieved optimal recovery of antimonate minerals (90.25%) at pH 8 with a dosage of 70 mg/L, while quartz recovery remained below 10%. Contact angle measurements revealed a significant increase in the hydrophobicity of antimonate minerals after SDS treatment, whereas quartz remained highly hydrophilic. FTIR and XPS analyses confirmed the selective chemisorption of SDS on antimonate mineral surfaces through Sb-O-S bond formation, while negligible adsorption occurred on quartz. Adsorption isotherms further showed the higher SDS uptake on antimonate minerals compared to quartz. These findings collectively demonstrate the effectiveness of SDS as a selective collector for the flotation of antimonate minerals, providing a promising approach to enhancing the recovery of fine antimonate particles. Full article

Several different types of burial were identified during the excavation of the Roman military cemetery associated with the fort at Birdoswald, on Hadrian’s Wall (UK). Fragments of glass vessels and glass beads were recovered from many of the cremation deposits, as they were commonly used during cremation rituals, and many of these had been affected by heat. X-ray fluorescence spectroscopy and scanning electron microscopy were used to investigate the raw materials, colorants and opacifiers employed to produce the glass assemblage. Most of the large fragments are transparent with a blue-green colour, with a composition typical of recycled glass. The smaller fragments are from beads and are coloured and sometimes opaque. Colourants and opacifiers characteristic of Roman glass were added in this glass formulation, including cobalt-based compounds (blue glass), copper alloys (green glass), white calcium antimonate, and yellow lead antimonate. The multianalytical approach of this research has allowed for the distinguishing of the extreme depletion of sodium on the surface of the melted glass fragments due to the exposure to high temperatures during the cremation process, followed by surface weathering in a burial environment. Based on the chemical composition of the bulk of the samples, a model of high temperature viscosity of glass was applied in order to assess the cremation temperature in the pyre, providing relevant information about funerary rituals and cremation technology in Roman Britain. Full article

Brizziite, a rare sodium antimonate (NaSb⁵⁺O₃), and fluorcalcioroméite ((Ca,Na)₂Sb⁵⁺₂O₆F), have been identified in two boreholes (Pasternik and Włosienica) which are situated 50 km apart. Both wells are located west of Krakow, Poland, and were drilled in the Miocene strata of the Paratethys Sea (a remnant of the Tethys Ocean). The Sb minerals are scattered in a solidified light blue silica gel within marls and layered clays. They occur most often as anhedral grains up to 20 μm in size. The presence of these phases was confirmed by Raman spectroscopy (RS) and X-ray diffraction (XRD). The brizziite from this study represents a secondary mineral after the alteration of roméite within a supergene zone, or crystallization from Sb-rich solutions derived by the leaching of the weathered primary roméite. Hence, the calcium and fluorine admixtures in their composition, determined by EPMA, indicate intergrowths of brizziite and roméite on the micro- to crypto-scale. The presence of the antimony in the study area is related to rejuvenated Old-Paleozoic polymetallic ore-mineralization occurring in the basement of the Krakow-Silesia Monocline. The phenomenon of the repeatability of brizziite in Pasternik and Włosienica, distant by several tens of kilometers, can be explained by the following three steps: (i) the penetration of the chloride ions from the drying up seawaters of the Paratethys Sea into the Miocene groundwater system, (ii) the mobilization of Sb⁵⁺ in the form of chloride complexes, and, finally, (iii) the transportation of the Sb-bearing solutions within the marly and clay sediments. Full article