| The reactivity of 15 component minerals of beach sands with sodium hydroxide has been investigated by means of differential thermal analysis in a temperature range up to∼700℃ in two size ranges: 72/300 and -300 mesh fractions. A modified metallic sample holder made of pure silver was employed along with a conventional D. T. A. set-up. The minerals include eleven economic minerals (monazite, zircon, columbite, wolframite, rutile, xenotime, scheelite, apatite, chromite, ilmenite, cassiterite) and four associated gangue minerals(quartz, tourmaline, garnet, hematite). The D. T. A. thermograms showed that all the minerals except cassiterite, ilmenite and hematite reacted within the temperature range considered. Two typical reaction temperatures were observed: one in the temperature range below the m. p. of NaOH(157∼250℃, most of fine minerals) and the other on the melting(300∼350℃). A graphical summary of the test results according to the reaction peaks has been established to visualize the reactivity of the groups of minerals. |
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