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We present a carbonation-assisted flotation method for nickel (Ni) separation from low-grade ultramafic ores. The high process economics of conventional flotation of low-grade ultramafic ores makes Ni unrecoverable on an industrial scale. Based on the fundamentals of CO2 sequestration in minerals, we carbonated a low-grade serpentine (lizardite) ore specimen under extreme conditions (185 °C, 15 MPa, and 24 h) and attained a conversion efficiency of serpentine to magnesite of 22% and 16% in the presence and absence of inorganic salts, respectively. Rhombohedral structures on carbonated particles detected using scanning electron microscopy suggested the formation of magnesite. We also found that Ni–Fe existed as sulfides, as confirmed by elemental mapping micrographs, and did not leach out as Ni2+ and Fe2+, as confirmed through carbonation supernatant analysis. Here, we introduced Denver cell froth flotation experiments after carbonation, which showed that the carbonated ore in the presence of inorganic salts had 29% higher Ni recovery and 0.15 wt% higher nickel grade than the uncarbonated ore. This study is the first to successfully show that the carbonation of serpentine containing nickel-bearing pentlandite leads to magnesite formation, does not lead to the dissolution of nickel sulphide, and enhances the nickel separation efficiency during froth flotation. This study paves the path forward for the integration of mineral carbonation in the processing of low-grade ultramafic nickel ores. [ABSTRACT FROM AUTHOR]

This work outlines a new approach for modifying conventional RFID tags with chemically sensitive conductive composites. Conductive composite films were integrated into the RFID tag circuit. As the film was exposed to selected analytes the film swelled increasing the resistance of the film and decreasing the communicating ability of the RFID tag. Using maleic anhydride as the sensing material, the composite was able to detect different biogenic amines associated with food spoilage. RFID tag response was found to depend on amine concentration, tag initial resistance and type of biogenic amine. RFID sensors of this nature are attractive for a number of applications in the gaseous sensing industry. [ABSTRACT FROM AUTHOR]

We investigated the flow dynamics of biotin-conjugated microgel capsules in avidin-conjugated microchannel constrictions. Microgels were prepared using a microfluidic assembly approach. Biotinylated microgels passing through avidin-modified constrictions slowed relative to several control systems. This effect was observed below a critical velocity of the microgels in the channel-at-large. The reduction in microgel velocity in the constriction occurred for several different sizes of microgels and orifices. Soft compliant microgels showed a lower velocity in the constriction relative to rigid microgels with the same concentration of biotin on the surface, due to the ability of the softer microgels to deform in the orifice and maximize their surface area when in contact with the orifice wall.