Utilization of DTAB as a collector for the reverse flotation separation of quartz from fluorapatite

Reverse flotation desilication is an indispensable step for obtaining high-grade fluorapatite. In this work, dodecyltrimethylammoni- um bromide (DTAB) is recommended as an efficient collector for the reverse flotation separation of quartz from fluorapatite. Its collectivity for quartz and selectivity for fluorapatite were also compared with figures corresponding to the conventional collector dodecylamine hydrochlor- ide (DAC) via microflotation experiments. The adsorption behaviors of DTAB and DAC on minerals were systematically investigated with surface chemical analyses, such as contact angle determination, zeta potential detection, and adsorption density measurement. The results re- vealed that compared to DAC, DTAB displayed a similar and strong collectivity for quartz, and it showed a better selectivity (or worse col- lectivity) for fluorapatite, resulting in a high-efficiency separation of the two minerals. The surface chemical analysis results showed that the adsorption ability of DTAB on the quartz surface was as strong as that of DAC, whereas the adsorption amount of DTAB on the fluorapatite surface was much lower than that of DAC, which is associated with the flotation performance. During the floatation separation of the actual ore, 8wt% fluorapatite with a higher grade can be obtained using DTAB in contrast to DAC. Therefore, DTAB is a promising collector for the high-efficiency purification and sustainable utilization of valuable fluorapatite recourses.

Controlling the Shape, Pore Size and Surface Area of Prepared Mesoporous Silica Particles by Altering the Molar Concentration of Tetramethoxysilane

In recent days, the applications of silica-based nanoparticles have gained much attention. The preparation of mesoporous silicas is usually achieved via the modified Stöber method, the reaction attained by the hydrolysis and condensation of silica precursors present within a medium containing template, solvent, deionized water (DI-W) and base. Therefore, the current study aimed to prepare and characterize mesoporous silicas by using tetramethoxysilane (TMOS) as silica precursor and ethylene glycol (Et-G) as solvent. The study was based on the template dodecyltrimethylammonium bromide (C12TMABr) and sodium hydroxide used as an alkaline agent. Mesoporous silicas were prepared in various batches based on TMOS molar concentration, ionized water, NaOH, and other solvents. The characterization of mesoporous silicas was achieved based on their specific surface area, pore size distribution and morphology using different instruments: Brunauer, Emmett & Teller (BET), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and thermalgravimetric analysis (TGA). The study revealed that shape, average particle sizes “35 to 550 nm”, average pore radius “1.62 - 4.5 nm” and surface area “350 - 1204 m2·g-1” of obtained mesoporous silica particles were altered based on precursor concentration and other factors. Therefore, it is important to get the most suitable concentration of all chemicals in the preparation of mesoporous silicas to control the particle characteristics to use them upon their further applications. This is the baseline study that provides details regarding prepared silica particles with controlled characteristics, and more studies related to its applications are still in process.