Synergistic mechanism between SDBS and oleic acid in anionic flotation of rhodochrosite

Pure mineral flotation experiments, zeta potential testing, and infrared spectroscopy were employed to investigate the interracial reactions of oleic acid （collector）, sodium dodecyl benzene sulfonate （SDBS, synergist）, and rhodochrosite in an anionic system. The pure mineral test shows that oleic acid has a strong ability to collect products on rhodochrosite. Under neutral to moderately alkaline conditions, low temperature （e.g., 10℃） adversely affects the flotation performance of oleic acid; the addition of SDBS significantly improves the dis- persion and solubility of oleic acid, enhancing its collecting ability and flotation recovery. The zeta potential test shows that rhodochrosite interacts with oleic acid and SDBS, resulting in a more negative zeta potential and the co-adsorption of the collector and synergist at the mineral surface. Infrared spectroscopy demonstrated that when oleic acid and SDBS are used as a mixed collector, oleates along with -COO- and --COOH functional groups are formed on the mineral surface, indicating chemical adsorption on rhodochrosite. The results demonstrate that oleic acid and SDBS co-adsorb chemically on the surface ofrhodochrosite, thereby improving the flotation performance of the collector.

Alkaline pretreatment for chlorine removal from high-chlorine rhodochrosite

Chloride in manganese ore adversely affects mineral extraction. The mechanisms and the factors that influence an alkali pretreatment to removal chlorine from manganese ore were explored to eliminate hazards posed by chlorine during the electrolysis of manganese. The results showed that sodium carbonate, when used as an alkaline additive, promoted the dissolution of insoluble chloride, enhanced the migration of chloride ions, and effectively stabilized Mn^（2＋）. The optimal conditions were a sodium carbonate concentration of 0.45 mol·L^（-1）, a liquid-solid ratio of 5：1 mL ·g^（-1）, a reaction time of 1 h, and a temperature of 25°C. The chlorine removal efficiency was greater than 95%, and the ore grade（Mn） was increased by 2.7%.

Effect of Iron on the Stability of Rhodochrosite at the Topmost Lower Mantle Conditions

Carbonates are viewed as the principal oxidized carbon carriers during subduction,and thus the stability of subducted carbonates has significant implications for the deep carbon cycle.Here we investigate the high pressure-temperature behaviors of rhodochrosite in the presence of iron up to∼34 GPa by in-situ X-ray diffraction and ex-situ Raman spectroscopy.At relatively low temperature below∼1500 K,MnCO_(3)breaks down into MnO and CO_(2).Upon heating to∼1800 K,however,the MnCO_(3)-Fe^(0)reactions occur with the formation of Mn_(3)O_(4),Fe^(O)and reduced carbon.A'three-stage'reaction mechanism is proposed to understand the kinetics of the carbon-iron-manganese redox coupling.The results suggest that Fe^(0)can serve as a reductant to greatly affect the stability of rhodochrosite,which implies that the effect of Fe-metal should be seriously considered for the high pressure-temperature behaviors of other predominant carbonates at Earth's mantle conditions,particularly at depths greater than∼250 km.