羧甲基淀粉的取代度对其在反浮选中抑制-水硬铝石的影响

摘要

研究取代度不同的两种羧甲基淀粉(CMSL和CMSH分别表示取代度低和取代度高的羧甲基淀粉)在以十二胺(DDA)为捕收剂的阳离子反浮选中对一水硬铝石的抑制性能.考察了CMS的取代度对其抑制性能及作用方式的影响.单矿物浮选实验表明,在广泛pH值范围内,CMSL对一水硬铝石的抑制能力要好于CMSH.借助吸附量测试、动电位测量和原子力显微镜对CMS在一水硬铝石表面的吸附进行研究.结果表明:相对于CMSL,CMSH分子中具有更多的吸附点,因而在一水硬铝石表面具有较小的吸附量和较薄的吸附层厚度,并使一水硬铝石表面具有较强的电负性.溶液表面张力的测定和捕收剂DDA的吸附实验进一步揭示,CMSL分子的环式吸附构象可以罩盖更多的DDA从而显示优良的抑制性能,而CMSH/DDA体系则表现得更像一种表面活性剂.%Carboxymethyl starchs (CMS) with low and high degrees of substitution (CMSL and CMSH in short,respectively) were employed as depressants of diaspore in cationic reverse flotation using dodecylamine (DDA) as collector.The effect of degree of substitution of CMS on its depression performance was examined and the interaction mode and behavior were investigated in a comparative manner.Micro-flotation test showed that CMSL exhibited better performance in depressing diaspore than CMSH in a broad pH range.The adsorption of CMS on diaspore was studied by adsorption test,zeta potential measurement,and atomic force microscopy.It was found that CMSH corresponds to lower adsorption amount,thinner adsorption layer,and more negative charge than CMSL,resulting from the more chelating sites brought by the high degree of substitution.The surface tension measurement and DDA adsorption test further revealed that CMSL/DDA system gives a better depressing performance benefiting from the trapping effect by enveloping some DDA molecules inside the loop chains,while CMSH/DDA system is likely considered a quasi-surfactant.