Selective depression behavior of guar gum on talc-type scheelite flotation

The depression behavior and mechanism of guar gum on talc-type scheelite flotation were systematically investigated by flotation experiments, adsorption tests, zeta-potential measurements, and infrared spectroscopic analyses. The flotation results for monominerals, mixed minerals, and actual mineral samples indicated that guar gum exhibited much higher selective depression for talc than for scheelite. Bench-scale closed-circuit tests showed that a tungsten concentrate with a WO_3 grade of 51.43% and a WO_3 recovery of 76.18% was obtained. Adsorption tests, zeta-potential measurements, and infrared spectral analyses confirmed that guar gum absorbed more strongly onto the talc surface than onto the scheelite surface because of chemisorption between guar gum and talc. This chemisorption is responsible for the guar gum's highly selective depression for talc and small depression for scheelite. The flotation results provide technical support for talc-type scheelite flotation.

The selective effect of food-grade guar gum on chalcopyrite-monoclinic pyrrhotite separation using mixed aerofloat(CSU11) as collector

The flotation separation of chalcopyrite from monoclinic pyrrhotite using food-grade guar gum(FGG) as a depressant was studied through flotation tests, kinetic studies, dynamic potential measurements, adsorption experiments, and infrared spectral analyses. The microflotation results showed that the flotation separation of chalcopyrite from monoclinic pyrrhotite could not be realized by adding mixed aerofloat(CSU11) alone. The depressant FGG exhibited a selective depression effect on monoclinic pyrrhotite by controlling the pulp pH range from 5.0 to 6.0, with a maximum floatability variation of 79.36% in the presence of CSU11. The flotation kinetics, zeta-potential, adsorption, and infrared spectroscopy studies revealed that the FGG could absorb more strongly on the surface of monoclinic pyrrhotite than on the surface of chalcopyrite. In addition, the results revealed that the interaction of FGG with the monoclinic pyrrhotite surface was governed primarily by strong chemisorption, whereas FGG mainly bonded to chalcopyrite through hydrogen bonding. This difference was responsible for the excellent depression selectivity of FGG toward monoclinic pyrrhotite flotation and weak depression effect toward chalcopyrite flotation.

斑岩型铜钼矿等可浮浮选回收钼和铜（英文）

为了有效提高多宝山斑岩铜钼矿的辉钼矿回收率,开发了铜钼等可浮浮选的工艺流程。系统地考察了浮选方案、捕收剂种类、磨矿细度、粗选p H值及药剂用量对辉钼矿浮选回收的影响。结果表明,与煤油、柴油相比,变压器油在水中具有较强的分散能力,且对辉钼矿的浮选选择性较优,因而在低用量条件下便可获得较高的钼回收率。另外,与混合浮选方案相比,等可浮浮选方案利用变压器油作捕收剂不仅可获得较优的铜钼混合精矿(钼回收率和品位分别为90.77%和0.80%),而且能提高钼精矿的钼回收率在18%以上、钼品位在5%以上。工业浮选试验结果进一步表明,采用等可浮浮选方案选别该斑岩铜钼矿是行之有效的。

N-丙基-N′-乙氧羰基硫脲对黄铜矿和黄铁矿的浮选及其电化学行为（英文）

通过浮选试验,比较N-丙基-N′-乙氧羰基硫脲(PECTU)和丁基黄药(BX)对黄铜矿和黄铁矿浮选行为的影响,并利用动电位测试和电化学方法研究乙氧羰基硫脲与黄铜矿和黄铁矿的作用机理。浮选试验结果表明,相对于丁基黄药,乙氧羰基硫脲表现出对黄铜矿更强的捕收能力以及更好的选择性。与PECTU作用后,黄铜矿表面zeta电位向正方向移动,证明PECTU在黄铜矿表面发生了吸附。循环伏安曲线和塔菲尔测试结果表明,PECTU与黄铜矿表面相互作用后,吸附在黄铜矿电极表面的PECTU阻碍了黄铜矿自身的氧化和腐蚀。动电位和电化学测试结果表明,在弱碱性条件下,PECTU与黄铁矿几乎无相互作用。

过程pH刺激对游离和吸附菌协同浸出黄铜矿的影响（英文）

为了研究过程pH刺激对中度嗜热菌浸出黄铜矿的影响,测定浸出过程中铜的浸出率以及游离和吸附菌的微生物群落结构动态变化。结果表明,将浸出第14天浸出过程的pH分别调节至1.0及3.0时,游离菌和吸附菌的生长均出现一个适应期。同时,未调节pH的对照组铜的浸出率为87.5%;而调节过程pH至1.0和3.0时,铜的浸出率分别下降至86.9%和64.0%。实时定量PCR分析表明,pH刺激对吸附菌的影响比对游离菌的影响小,说明吸附菌比游离菌对过程pH刺激具有更强的抗性。此外,调节过程pH至3.0显著破坏了游离菌和吸附菌的群落结构,浸出体系无法恢复至正常状态。

酸性培养基体系中磁铁矿对砷黄铁矿电化学氧化的原电池效应

采用电化学测试、XPS和浸出试验,研究酸性培养基体系中砷黄铁矿与磁铁矿之间的原电池效应。结果表明,磁铁矿的静电位为321 mV,高于砷黄铁矿的223 mV,两者之间的原电池电流为7.40μA,证明砷黄铁矿和磁铁矿之间确实存在原电池效应。原电池电位和极化曲线表明,砷黄铁矿的氧化还原行为在整个原电池反应中占主导地位,原电池反应可强化砷黄铁矿的电化学溶解,促进表面氧化产物(S^(0),SO_(3)^(2−),SO_(4)^(2−)和AsO_(3)^(3−))的生成,提高砷黄铁矿表面的化学反应活性。6 d的浸出试验表明,在磁铁矿存在下,砷黄铁矿中砷的溶出浓度提高30 mg/L,进一步证明磁铁矿对砷黄铁矿的氧化具有强化作用。

铜离子对铁闪锌矿溶解机制的影响

通过实验和密度泛函理论(DFT)模拟计算研究铜离子存在下铁闪锌矿的溶解机制。浸出实验结果表明,铜离子在高温条件下(高于55℃)加速铁闪锌矿的溶解,但在低温条件下(低于45℃)抑制其溶解。导致该现象的原因可能是铜离子与铁闪锌矿间的反应机制随反应温度的升高从表面吸附反应转变为体相取代反应。体相取代反应使铁闪锌矿晶格中更多的锌原子被释放,并且取代反应产物,增强铁闪锌矿表面的电化学反应活性;然而,低温条件下铜离子的吸附会使铁闪锌矿表面钝化,从而阻碍电化学反应的进行。DFT模拟计算表明,高温条件下取代反应的反应能比表面吸附反应能更负,进一步验证了所提出的反应机制。

Seaweed glue as a novel polymer depressant for the selective separation of chalcopyrite and galena

The use of seaweed glue(SEG)as a novel polymer depressant for the separation of chalcopyrite from galena with butyl xanthate(BX)as a collector was studied through microflotation experiments.Contact angle,adsorption,dynamic potential,and infrared spectral analyses were conducted to clarify the mechanism underlying the action of SEG on minerals.The results of microflotation experiments indicated that chalcopyrite could be selectively separated from galena by using a SEG depressant concentration of 15 mg·L^-1,BX concentration of 10 mg·L^-1,and methyl isobutyl carbinol concentration of 8.5 mg·L^-1 at pH 8.0.A Cu concentrate with a grading of 23.68wt% was obtained at a recovery rate of 81.52% from mixed minerals with 8.29wt% Cu content.Contact angle analysis showed that the effect of SEG on the wettability of galena was stronger than that on the wettability of chalcopyrite.Adsorption,zeta potential,and FT-IR spectral analyses revealed that SEG and BX were coadsorbed on the surfaces of galena.SEG depressed galena by covering xanthate ions in the functional groups of-COO and mainly underwent weak physisorption on chalcopyrite.These mechanisms account for the ability of SEG to depress galena effectively while enabling chalcopyrite flotation.

Preparation of manganese sulfate from low-grade manganese carbonate ores by sulfuric acid leaching

In this study, a method for preparing pure manganese sulfate from low-grade ores with a granule mean size of 0.47 mm by direct acid leaching was developed. The effects of the types of leaching agents, sulfitric acid concentration, reaction temperature, and agitation rate on the leaching efficiency of manganese were investigated. We observed that sulfuric acid used as a leaching agent provides a similar leach- ing efficiency of manganese and superior selectivity against calcium compared to hydrochloric acid. The optimal leaching conditions in sul- furic acid media were determined; under the optimal conditions, the leaching efficiencies of Mn and Ca were 92.42% and 9.61%, respec- tively. Moreover, the kinetics of manganese leaching indicated that the leaching follows the diffusion-controlled model with an apparent ac- tivation energy of 12.28 kJ·mol-l. The purification conditions of the leaching solution were also discussed. The results show that manganese dioxide is a suitable oxidant of ferrous ions and sodium dimethyldithiocarbamate is an effective precipitant of heavy metals. Finally, through chemical analysis and X-ray diffraction analysis, the obtained product was determined to contain 98% of MnSOa4·H20.

Effect of pH values on the extracellular polysaccharide secreted by Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

The pH value plays an important role in the bioleaching of sulphide minerals. The effect of pH values on the extracellular poly-saccharide secreted by Acidithiobacillus ferrooxidans was investigated in different phases of bacterial growth during chalcopyrite bioleach-ing. It is found that extracellular polysaccharide secretion from the cells attached to chalcopyrite is more efficiently than that of the free cells in the bioleaching solution. Three factors, pH values, the concentration of soluble metal ions, and the bacterial growth and metabolism, affect extracellular polysaccharide secretion in the free cells, and are related to the bacterial growth phase. Extracellular polysaccharide secretion from the attached cells is mainly dependent on the pH value of the bacterial culture.

Flotation mechanisms of molybdenite fines by neutral oils

The flotation mechanisms of molybdenite fines by neutral oils were investigated through microflotation test, turbidity measure- ments, infrared spectroscopy, and interracial interaction calculations. The results of the flotation test show that at pH 2-11, the floatability of molybdenite fines in the presence of transformer oil is markedly better than that in the presence of kerosene and diesel oil. The addition of transformer oil, which enhances the floatability of molybdenite fines, promotes the aggregation of molybdenite particles. Fourier transform infrared measurements illustrate that physical interaction dominates the adsorption mechanism of neutral oil on molybdenite. Interracial inte- raction calculations indicate that hydrophobic attraction is the crucial force that acts among the oil collector, water, and molybdenite. Strong hydrophobic attraction between the oily collector and water provides the strong dispersion capability of the collector in water. Furthermore, the dispersion capability of the collector, not the interaction strength role in the flotation system of molybdenite fines. Our findings provide between the oily collectors and molybdenite, has a highly significant insights into the mechanism ofmolybdenite flotation.