Papers by Keyword: Ultra-Fine

Abstract: It is known that oxidation is one of the most common ways for penlandite to be introducted into tailing during traditional coarse-particle sulfide flotation. However, it could become much more complicated and challenging problems for the low-grade, fine-disseminated Cu-Ni sulfides containing Pt and Pd in Yunnan Mine, accompanied with more than 75% of the content of MgO in the ore sample is. Direct flotation tests had been conducted to extract the metallic values as much as possible by adding traditional depressants and collectors, such as carboxylmethyl cellulose, starch, sodium silicate, butyl xanthate, (BX), butyl ammonium dithophosphate (BA) and etc., the relatively satisfied recoveries of Cu, Ni, Pt and Pd in the concentrate from bench flotation tests were obtained, however, more than 30% of metallic values still lost in the slime. In this study, bench flotation tests for the ore sample fromYunnan Mine, micro-flotation tests of serpentines and pentlandite from Jinchuan Mine and their settling rate tests were conducted to figure out how the oxidation influence the recovery of the ultra-fine nickel sulfide. All the tests results pointed to the presence of over-oxidation on the ultra-fine nickel sulfide surface and lead to the loss of Ni containing Pt and Pd in the slime tailing. Some methods which tried to slow the speed of oxidation on mineral surface during grinding and flotation were introduced in order to recover the values before over-oxidation of sulfides; however, the slime coating of serpentines also may play an important role in disturbing the floatability of ultra-fine sulfide.

Abstract: Ultra-fine titanium diboride (TiB2) powders have been prepared by carbothermal reduction reactions in TiO2-B2O3-C system using tetrabutyl titanate, boric acid and phenolic resin as the solution-derived precursors. The reactions were substantially completed at relatively lower temperature (<1400°C) and the resulting products had a smaller average crystallite size (< 200 nm). However, below 1100°C, titanium carbide was the predominant phase and the relative content decreased with the rise of temperature. The thermodynamic change in TiO2-B2O3-C system was mainly studied by TG-DTA and the mechanism of synthesis of TiB2 was discussed. The crystallite size and morphology of the synthesized powders were characterized by SEM and TEM.

Abstract: BaTiO3 and SrTiO3 ultrafine powders are synthesized from sodium hydrogen titanate nanowires using hydrothermal route. Their preparation and purity depend strongly on the pH value of reaction system (the amount of added alkaline). Under the reaction condition of strong alkaline, the BaTiO3 phase can be obtained, but the SrTiO3 phase can not be easily prepared. Without the addition of any alkaline, the pure SrTiO3 phase can be synthesized. Reaction time also affects on the purity of BaTiO3 phase. Below 15 h of reaction time at reaction temperature 180°C, pure BaTiO3 phase can not be prepared. SEM measurement results show that the average diameter of BaTiO3 powders is about 200 nm and that of SrTiO3 submicrorods is about 300 nm. Their Raman spectra further demonstrate that the prepared products are BaTiO3 and SrTiO3 phases.