The Carboxyl Hydroxamic Acid Synthesis And The Separation Performance Of A Diaspore And Al-si Mine

Bauxite resources are very abundant in China, but mainly as diasporic type, with the characteristics of high alumina, high silica and low Al2O3 to SiO2 mass ratio (A/S) (A/S less than 7 possesses about 72% of the bauxite resources). This type of bauxite is difficult to be treated directly by the Bayer process. It is therefore highly desirable to increase the mass ratio of A/S by flotation desilication before Bayer-process since its highly economical efficiency. Theoretically, two approaches may be taken for the flotation desilication of diasporic bauxite, that is, direct flotation desilication characterized by the flotation of diaspore and the depression of aluminosilicates and reverse flotation desilication characterized by the flotation of aluminosilicates and the depression of diaspore. Not matter which approach, the flotation reagent is important and the critical technique. Flotation removal of silicon in collector research, combination of conventional reagents were reported a lot, such as oleic acid, tall oil, sodium oxide, wax soap,733, styrene phosphoric acid, aliphatic hydroxamic acid, aromatic hydroxamic acid conventional anionic organic compounds or mixtures thereof, but the results are not very satisfactory.The carboxyl and hydroxyl were implanted in the same molecule, obtained a new type of anionic chelating collector——carboxy hydroxamic acid:DBCA, BDHA and BPHA. Single mineral flotation tests found that the DBCA obtained a recovery rate of diaspore about 97%(DBCA of concentration is 2×10-4 mol/L, pH=7.0), while those of BDHA and BPHA are only 50% and 45% respectively. But the three reagents to the flotation of aluminosilicates are poor. Subsequently, the floatability of diaspore, kaolinite and illite was measured by using DBCA as a collector, and the interaction mechanism between minerals and DBCA was investigated through zeta potential measurements and FT-IR spectrum, and structure and property relationship of collector were also discussed. The flotation experimental results showed that DBCA had a very strong collecting ability for diaspore, while poor activity was observed for kaolinite and illite. The interaction of DBCA on diaspore surfaces is mainly dominated by chemical bonding as the formation of three chelation rings; however, those on the surfaces of kaolinite and illite are mainly hydrogen bonding or physical adsorption. Meanwhile, zeta potential measurement showed that a diaspore, kaolinite and illite isoelectric point (IEP) were 6.2,3.8 and 3.0. Consequently, it is possible to separate diaspore from such aluminosilicates as kaolinte and illite employing DBCA as a collector.