查看更多>>摘要：It is possible to analyze in situ the adsorbate/adsorbant interaction during the flotation process by high frequency dielectric measurements. The adsorption of complexing collector (sodium oleate) onto calcite increases the dielectric permittivity independently of the frequency. The dielectric constant increases after adsorption because the adsorbate and the adsorbant interact through covalent bonds. Physical adsorption involving electrostatic interactions or hydrogen bonds (dodecylamine and dodecylsulfate) has no effect on the dielectrical characteristics. The dielectric method allows to analyze the mechanisms of depression using reagents such as quebracho and sodium silicate. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：Associated minerals in the raw coal increase the energy consumption and abrasion of grinding media of vertical spindle pulverizer (VSP). Moreover, the low separating efficiency of classifier in VSP leads to the return of fines to grinding table, worsens the grinding phenomenon and make the energy-size reduction of coal complex. Beneficiation of fines rejected by classifier is helpful to save energy and decreases the air pollution caused by the combustion of minerals in fines. Aiming to evaluate the potential for beneficiating the circulating loads, multi analytical techniques are utilized to the raw coal and ground products. Phase composition analyses of raw coal show that kaolinite is the main mineral. Comparison of scanning electron microscopy and energy dispersive Xray spectroscopy (SEM-EDX) of coal before and after comminution illustrates the liberation of kaolinite from coal substance, and the measurement of charge-mass ratios indicates the opposite polarity of tribocharge between coal and minerals, which indicates the separating possibility based on difference in the electric physics. Removal results of minerals from circulating loads by the triboelectrostatic separator vary with product fineness and liberation degrees. The best separation result is obtained on the finest progenies produced with the yield and ash content of clean coal at 61.95% and 18.92%, respectively. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：The reactivity of cemented paste tailings (CPT) that contains sulphide mineral-bearing tailings is a key parameter that influences its environmental performance and durability. This reactivity can be influenced by several factors, such as the initial sulphate content of the CPT. In this paper, the effect of the initial sulphate content of the CPT on its reactivity is experimentally investigated by conducting oxygen consumption (OC) tests on CPT specimens. Microstructural testing is also conducted on CPT specimens to better understand the mechanisms responsible for the changes in the reactivity of CPT. These specimens are prepared by mixing defined amounts of pyritic tailings (45 wt%), varying proportions of Portland cement type I or Portland cement partially replaced with different types and amounts of mineral admixtures, and mixing water with various sulphate contents (0, 5000,15,000 and 25,000 ppm). The samples are cured for 150 days at room temperature. The results show that regardless of the type of binder, the reactivity of the CPT specimens increases with increasing contents of sulphate except for a sulphate content of 5000 ppm Also, partial substitution of Portland cement type I with mineral admixtures, such as granulated blast furnace slag or fly ash, reduces the chemical reactivity. Regardless of the initial sulphate content, increasing the cement content and/or replacing cement with mineral admixtures leads to the reduction in the reactivity of the paste. (C) 2017 Elsevier B.V. All rights reserved.
Iyakwari, ShekwonyaduGlass, Hylke J.Obrike, Stephen E.
5页
查看更多>>摘要：The preconcentration or early rejection of gangue minerals in mineral processing operations is investigated using sorting, based on interpretation of near infrared sensor data collected from ore particles. The success of sorting depends on the distribution of minerals between particles, the arrangement or association of minerals within particles and the ability of near infrared to distinguish relevant minerals. This paper considers minerals association, using common alteration minerals found in a hydrothermally-formed" copper ore, with sensitivity in the near infrared region. The selected NIR-active minerals were arranged along the view of NIR line scanner to stimulate adjacent natural minerals association.
Linden, Johan B.Zhang ZihaoAddai-Mensah, JonasNyden, Magnus...
8页
查看更多>>摘要：To date, the quest for cost-effective methods for removal of dissolved metals from aqueous solutions remains a daunting challenge for many industries. This paper reports on the development of an effective, hybrid adsorbent for selective copper recovery from aqueous solutions under industrially relevant conditions. The work involved (i) purification and functionalization of diatomaceous earth (DE) particles with glutaraldehyde(GA)-crosslinked polyethyleneimine(PEI), (ii) physicochemical characterization of the product and (iii) metal adsorption from solutions containing-Cu(II)/Ni(II)/Fe(11)/Ca(11)/Mg(II)/Mn(II)/AI(III)/Na ions and their subsequent elution behaviour. Acid leaching of the pristine DE led to a significant reduction in its metal oxide (e.g., Al2O3, Fe2O3) constituents and a concomitant increase in both SiO2 content and specific surface area. Upon functionalization with GA-crosslinked PEI, the DE particles' interfacial chemistry was completely altered to that of the polymer with no change in specific surface area. Isothermal batch adsorption from saline (15 g/dm(3) NaCl) and non-saline solutions containing 500 and 1000 mg/dm(3) of Cu at similar to pH 4 revealed >97% Cu(II) removal by functionalized DE within 3 min in both cases. Subsequent water elution tests at pH 1 showed complete release of the adsorbed Cu confirming pH-dependent interaction between dissolved Cu and GA-crosslinked PEI. The preliminary batch adsorption/elution tests involving 1000 mg/dm(3) solutions of Ni, Ca, Mg, Mn, Fe, Na and Al showed little or negligible affinity of the functionalized DE towards these elements, suggesting good selectivity for Cu. Furthermore, it is shown that the functionalized particles are chemically stable at H2SO4 concentrations up to 2 M and may be recycled >10 times without loss in their Cu adsorption/desorption performance. Crown Copyright (C) 2017 Published by Elsevier B.V. All rights reserved.
查看更多>>摘要：The pressure oxidation process to prepare sodium pyroantimonate from sodium thioantimonite solution was optimized. The results indicate that increasing reaction temperature, oxygen partial pressure and stirring speed can significantly accelerate the oxidation precipitation rate of Sb. A decrease in Sb3+ concentration is beneficial for shortening the reaction time. The NaOH concentration has no significant effect on the oxidation velocity but plays an important role in the quality of sodium pyroantimonate. An increase in stirring speed and oxygen partial pressure result in the formation of a red precipitation in the solution with 12.5 g/I. of NaOH, while the desired sodium pyroantimonate can be produced with a NaOH concentration of 30.0 g/L. The XRD and SEM-EDS analysis confirm that the red precipitate is composed of NaSb(OH)(6) and Na6Sb4S9. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：A hydrometallurgical process was developed to recover Co(II) and Ni(II) from the chloride leach liquor of laterite ore. Most of Co(II) and Ni(II) together with a small amount of A1(III) were selectively extracted over other elements by Cyanex 301 from the feed solution at pH 1 which contained Co(II), Ni(II), Al(III), Ca(II), Mg(II) and Mn(II). From the loaded Cyanex 301, Co(II) and Al(lll) were selectively stripped by 3 M HCl solution, and then Ni(II) was completely stripped by 10 M HCl solution. The McCabe-Thiele plots for the extraction and stripping isotherms were constructed. Batch simulation experiments for the counter-current extraction and stripping indicated that the recovery percentage of Co(II) and Ni(II) was 92.6 and 95.7%, respectively. Moreover, the purity of Ni(II) in the stripping solution was reached 99.5%. A process flowsheet for the recovery of Co(II) and Ni(II) from the laterite leach liquor was proposed. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this paper, a novel surfactant, N-butoxypropyl-S-12-(hydroxyimino) propyll dithiocarbamate ester (BOPHPDT) was first synthesized and introduced as a flotation collector for copper minerals. The micro and bench-scale flotation results demonstrated BOPHPDT exhibited superior flotation performance for chalcopyrite in comparison with xanthates and excellent selectivity against pyrite, and the preferable pH values for its attachment to chalcopyrite surfaces were 4-8. Adsorption thermodynamics and kinetics elucidated that BOPHPDT adsorption on to chalcopyrite was a spontaneously endothermic chemisorption process. The results of in situ scanning electrochemical microscopy (SECM) and zeta potential showed that BOPHPDT might anchor on the positively charge sites of chalcopyrite surfaces to form new species. Fourier transform infrared (FTIR) spectra further elucidated that BOPHPDT might react with the Cu atoms of chalcopyrite surfaces through its C=N-OH and NH-C(=S) groups. The double chelating groups and multiple hydrophobic chains of BOPHPDT, rendered it to possess excellent affinity and hydrophobicity for improving copper minerals flotation. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：An experimental study is conducted to investigate the effect of filling interval time (FIT) on the uniaxial compressive strength (UCS) and ultrasonic pulse velocity (UPV) of cemented coarse tailing backfill (CCTB). A total of 72 CCTB samples with diameter x height of 50 mm x 100 mm prepared at different solid contents (70, 72, and 75 wt%) and water-to-cement ratios (3.00, 2.72, and 233) were subjected to UPV and UCS tests at 12, 24, 36 and 48 h of FIT. The UCS and UPV values of the CCTB samples increased with the increase in the solid content. However, an increase in FIT led to a decrease in the UPV and UCS of the CCTB samples. Different types of curve fittings were conducted to obtain the correlation between UPV and UCS versus FIT at different solid contents. A polynomial function can explain the relationship between UPV and FIT. Moreover, the UCS and UPV values exhibit a linear function. CCTB also shows a failure mode of tensile failure-tensile shear failure transition -tensile and shear mixing failure modes, which provides a theoretical basis for the strength design and stability control of bacicfills. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：The study presents an evaluation of the possibility of using Class C fly ash for the synthesis of faujasite (Type X) and tschemichite (Type A) type zeolite materials. In order to obtain the well-formed zeolites, syntheses were carried out. The variables were: the ratio of NaOH to fly ash, water, the filtrate (post-reaction solutions obtained during the hydrothermal synthesis of zeolites rich in Si), and the amount of added aluminium foil. The analysis showed that three of the most effective reactions (from which Samples 21-23 were derived) occurred under the following conditions: the ratio of NaOH/fly ash was 1.6, 2.0 and 1.25, respectively, with a fusion temperature of 550 C (for each of the three reactions), fusion time of 1 h and reaction time of 4 h (for each of the three reactions); the amount of H2O was 100,100 and 50 ml; the amount of filtrate was 0, 0 and 50 ml; the amount of added aluminium foil was 0.5 g (for each of the three reactions); and the reaction temperature was 80 C (for each of the three reactions). The three best zeolite materials (Samples 21-23) that were derived were subjected to mineralogical (X-ray powder diffraction [XRD], scanning electron microscopy-energy-dispersive X-ray spectroscopy [ SEM-EDS]) and chemical (X-ray fluorescence [XRF]) characterization, with the addition of textural analysis (Brunauer-Emmett-Teller [BET] specific surface area and pore volume and size). Studies have shown that the obtained zeolites have a Type A (Samples 21-22) and Type X (Sample 23) structure, including well-formed grains with isometric and cubic characteristics. The calculated unit cell parameters of the obtained zeolites indicate a cubic crystal system and are very close to the reference values for structures of X and A type zeolites. The ratio of SiO2/Al2O3 in each of the three tested zeolite materials was as follows: 2.16,1.98 and 2.41. The specific surface area amounted to 106,104 and 256 m(2)/g for Samples 21-23, respectively. Obtained results were similar to the type of zeolite structures obtained from Class F fly ash. Therefore, we can conclude that the analysed Class C fly ash may also be a productive substrate for the synthesis of zeolite materials of Type X and A. (C) 2017 Elsevier B.V. All rights reserved.
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