Advances in depressants for flotation separation of Cu–Fe sulfide minerals at low alkalinity:A critical review

The flotation separation of Cu–Fe sulfide minerals at low alkalinity can be achieved using selective depressants.In the flotation system of Cu–Fe sulfide minerals,depressants usually preferentially interact with the pyrite surface to render the mineral surface hydrophilic and hinder the adsorption of the collector.This review summarizes the advances in depressants for the flotation separation of Cu–Fe sulfide minerals at low alkalinity.These advances include use of inorganic depressants (oxidants and sulfur–oxygen compounds),natural polysaccharides (starch,dextrin,konjac glucomannan,and galactomannan),modified polymers (carboxymethyl cellulose,polyacrylamide,lignosulfonate,and tricarboxylate sodium starch),organic acids (polyglutamic acid,sodium humate,tannic acid,pyrogallic acid,salicylic acid,and lactic acid),sodium dimethyl dithiocarbamate,and diethylenetriamine.The potential application of specific inorganic and organic depressants in the flotation separation of Cu–Fe sulfide minerals at low alkalinity is reviewed.The advances in the use of organic depressants with respect to the flotation separation of Cu–Fe sulfide minerals are comprehensively detailed.Additionally,the depression performances and mechanisms of different types of organic depressants on mineral surfaces are summarized.Finally,several perspectives on depressants vis-à-vis flotation separation of Cu–Fe sulfide minerals at low alkalinity are proposed.

The Relationship between Fe Mineralization and Magnetic Basement Faults using Multifractal Modeling in the Esfordi and Behabad Areas(BMD), Central Iran

Multifractal modeling is a mathematical method for the separation of a high potential mineralized background from a non-mineralized background. The Concentration-Distance to Fault structures(C-DF) fractal model and the distribution of the known iron(Fe) deposits/mines seen in the Esfordi and Behabad 1:100,000 sheets from the Bafq region of central Iran are used to distinguish Fe mineralization based on their distance to magnetic basement structures and surface faults, separately, using airborne geophysical data and field surveys. Application of the C-DF fractal model for the classification of Fe mineralizations in the Esfordi and Behabad areas reveals that the main ones show a correlation with their distance from magnetic basement structures. Accordingly, the distances of Fe mineralizations with grades of Fe higher than 55%(43% < Fe ≤ 60%) are located at a distance of less than 1 km, whereas for surfacial faults with grades of 43% ≤ Fe ≤ 60%, the distances are 3162< DF ≤ 4365 m from the faults. Thus, there is a positive relationship between Fe mineralization and magnetic basement structures. Also, the proximity evidence of Precambrian high-grade Fe mineralization related to magnetic basement structures indicates syn-rifting tectonic events. Finally, this C-DF fractal model can be used for exploration of magmatic and hydrothermal ore deposits.

Effect of Mineral Oil on the Mechanical Properties and Fractographs of Fe_3(Al,Cr,Zr) Intermetallic Alloy

The effect of mineral oil on the mechanical properties and fractographs of Fe3(Al,Cr,Zr) in termetallic alloy has been investigated. The results show that the tensile ductility of the Fe3(Al,Cr,Zr) alloy tested in oil is comparable with the results obtained in oxygen and is in sensitive to strain rate. The fracture mode of the Fe3(Al,Cr,Zr) alloy treated at 700℃/1.5 h and tested in oil, is cleavage and with dimples in some areas.

The performance of nitrate-reducing Fe(Ⅱ)oxidation processes under variable initial Fe/N ratios:The fate of nitrogen and iron species

The Fe/N ratio is an important control on nitrate-reducing Fe(Ⅱ)oxidation processes that occur both in the aquatic environment and in wastewater treatment systems.The response of nitrate reduction,Fe oxidation,and mineral production to different initial Fe/N molar ratios in the presence of Paracoccus denitrificans was investigated in 132 h incubation experiments.A decrease in the nitrate reduction rate at 12 h occurred as the Fe/N ratio increased.Accumulated nitrite concentration at Fe/N ratios of 2–10 peaked at 12–84 h,and then decreased continuously to less than 0.1 mmol/L at the end of incubation.N_(2)O emission was promoted by high Fe/N ratios.Maximum production of N_(2) occurred at a Fe/N ratio of 6,in parallel with the highest mole proportion of N_(2) resulting from the reduction of nitrate(81.2%).XRD analysis and sequential extraction demonstrated that the main Fe minerals obtained from Fe(Ⅱ)oxidation were easily reducible oxides such as ferrihydrite(at Fe/N ratios of 1–2),and easily reducible oxides and reducible oxides(at Fe/N ratios of 3–10).The results suggest that Fe/N ratio potentially plays a critical role in regulating N_(2),N_(2)O emissions and Fe mineral formation in nitrate-reducing Fe(II)oxidation processes.

Geology,Geochemistry and Re-Os Age of the Qiaoxiahala Deposit in NW China:Evidence of an Overprinted Fe(-Cu/Au)Deposit

Overprinting of an earlier formed deposit may obscure the nature of the deposit and hinder our understanding of regional metallogeny.The Qiaoxiahala Fe(-Cu/Au)deposit in eastern Junggar,NW China,is characterized by magnetite mineralization later replaced by sulfide minerals such as chalcopyrite.To reveal the genesis of Qiaoxiahala,we conducted Re-Os dating on post-magnetite molybdenite separated from chalcopyrite and rare earth elements(REEs)for basal-tic volcanic rock,magnetite,chalcopyrite and diorite.An isochron age of 377±7 Ma was obtained together with a weighted mean age of 375±3 Ma,which is indistinguishable from mineralization ages determined in previous studies.Rare earth element(REE)data for basaltic volcanic rocks hosting the ore are comparable to that of the magnetite,while the REE signatures of chalcopyrite from the Cu ore and local intrusive diorite share a similar pattern.These suggest that two distinct fluid sources are responsible for the deposition of Fe and Cu in the Qiaoxiahala deposit.According to these experimental results,we consider that the iron mineralization in Qiaoxiahala is the result of fluid exsolution from basaltic volcanism which was further overprinted by fluids that deposited copper and gold,which may have been sourced from nearby dioritic intrusions.