Enhanced inhibition of talc flotation using acidified sodium silicate and sodium carboxymethyl cellulose as the combined inhibitor

The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics.Besides,it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cellulose(CMC)alone during chalcopyrite flotation.Here,a combined inhibitor comprising acidified sodium silicate(ASS)and CMC was employed to realize effective flotation separation of chalcopyrite and talc,and the combined inhibition mechanism was further investigated.Microflotation results showed that adding ASS strengthened the inhibitory effect of CMC on talc and improved the separation of chalcopyrite and talc.The zeta potential,Fourier transform infrared,and X-ray photoelectron spectroscopy analysis indicated that CMC was mainly adsorbed on the talc surface via hydroxyl and carboxyl groups.Moreover,the addition of ASS improved the adsorption of carboxyl groups.Furthermore,the adsorption experiments and apparent viscosity measurements revealed that adding ASS dispersed the pulp well,which reduced the apparent viscosity,improved the adsorption amount of CMC on the talc surface,and enhanced the inhibition of talc in chalcopyrite flotation.

冻融循环下砂岩的非线性蠕变损伤模型

为了研究冻融循环与载荷的长期作用下岩石内部的损伤特性,以流变理论、损伤力学为基础,定义了基于核磁共振孔隙度的岩石冻融损伤因子与基于体应变的蠕变损伤因子,并将损伤因子引入基本流变元件中,建立了冻融岩石的非线性蠕变损伤本构模型与方程,用以描述冻融岩石在恒定载荷下的非线性蠕变特征。同时,开展了冻融岩石的分级加载蠕变试验,获得了冻融循环前后核磁共振孔隙度与岩石横向应变、纵向应变的变化情况。以试验数据为基础,分析并验证了冻融岩石蠕变损伤模型的适用性与准确性。结果表明,在冻融循环的作用下,岩石内部孔隙结构不断损伤劣化,核磁共振孔隙度持续增加;在恒定载荷的作用下,岩石的塑性变形增加,体积增长明显,蠕变时效损伤增强。随着加载应力的增加,岩石的瞬时弹性参数增大,流变弹性参数、黏性参数在快速降低;其中高应力水平对岩石具有硬化作用从而减弱部分损伤效应,使得后期流变弹性参数在小范围波动,而冻融循环的损伤劣化作用,使得岩石的黏塑性减弱,导致黏性系数随着冻融次数的增加而快速降低,但总体上岩石不断的损伤劣化,长期强度持续降低。本文建立的基于损伤因子的冻融岩石蠕变模型,能够准确描述冻融岩石的非线性特征。