Enhanced recovery of low-grade iron ore by selective flocculation method

Beneficiation of low-grade iron ore was carried out by selective flocculation process using different flocculants, namely starch amylopectin (AP) and grafted copolymer of amylopectin (GAP). The iron ore used in the investigation contained 56.98% Fe, 5.45% Al₂O₃, and 4.22% SiO₂. Flocculant dosage, number of floc washing, and pH were considered as variable parameters to analyze their effect on the performance of grade and recovery of concentrate. A flocculant dosage of 0.4?mg/g was found to be the optimum condition for the sample and variable parameters under investigation. The investigation indicated that a grade of 64.77% Fe can be obtained with 96% recovery using AP; however, GAP showed the better result for Fe grade (67%) with a recovery of 97%.     

Pump−probe experiments at the TEMPO beamline using the low‐α operation mode of Synchrotron SOLEIL

The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump–probe experiments. Among others, the low‐α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low‐α mode of the experimental set‐ups developed at the TEMPO beamline to perform pump–probe experiments with soft X‐rays based on photoelectron or photon detection are presented. A 282 kHz repetition‐rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two‐dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time‐resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high‐time‐resolution pump–probe experiments compared and discussed.     

Triazine‐based Organic Polymer‐catalysed Conversion of Epoxide to Cyclic Carbonate under Ambient CO2 Pressure

In this work we have achieved epoxide to cyclic carbonate conversion using a metal‐free polymeric catalyst under ambient CO₂ pressure (1.02 atm) using a balloon setup. The triazine containing polymer (CYA‐ANIS) was prepared from cyanuric chloride (CYA?Cl) and o‐dianisidine (ANIS) in anhydrous DMF as solvent by refluxing under the N₂ gas environment. The presence of triazine and amine functional groups in the polymer results in the adsorption of CO₂ up to 7 cc/g at 273 K. This inspired us to utilize the polymer for the conversion of a series of functionalised epoxides into their corresponding cyclic carbonates in the presence of tetrabutyl ammonium iodide (TBAI) as co‐catalyst. The product has wide range of applications like solvent in lithium ion battery, precursor for polycarbonate, etc. The catalyst was efficient for the conversion of different mono and di‐epoxides into their corresponding cyclic carbonates under atmospheric pressure in the presence of TBAI as co‐catalyst. The study indicates that epoxide attached with electron withdrawing groups (like, CH₂Cl, glycidyl ether, etc.) displayed better conversion compared to simple alkane chain attached epoxides. This is mainly due to the stabilization of electron rich intermediates produced during the reaction (e. g. epoxide ring opening or CO₂ incorporation into the halo‐alkoxide anion). This catalyst mixture was capable to maintain its reactivity up to five cycles without losing its activity. Post catalytic characterization clearly supports the heterogeneous and recyclable nature of the catalyst.     

Studies on selective flocculation of low-grade iron ore using statistical optimization

In this study, a two-level and three-variable full-factorial design is used to analyze the behavior of different variables of selective flocculation such as pulp density, pH, and flocculant dosage. The response of low-grade iron ore flocculation was investigated using a two-level and three-variable factorial design. From the studies, the optimal conditions were found to be pH (10), pulp density (6%), and flocculant dosage (0.5?mg/g), and the estimated values of for grade and recovery were 67.52% and 80.17%, respectively. The coefficients of determination (R²) for grade and recovery were found to be 99.80% and 99.97%, respectively.