查看更多>>摘要：The effect of mechanical activation on the atmospheric pressure leaching of a lateritic nickel ore was investigated to develop a superior alternative. Under the influence of mechanical activation, certain physico-chemical changes were observed. Accelerated leaching kinetics and less sulfuric acid consumption were found as the most beneficial effects of mechanical activation. 80.6% Ni and 84.5% Co in leach were obtained with the mechanically activated sample after 2 h of leaching in 30% H2SO4 at 85 C-omicron and 1/2.5 solid/liquid ratio (w/w). When non-activated sample was leached under the same conditions, similar metal extractions could be obtained after 8 h of leaching. Finally, a process flow sheet was developed including mechanical activation of the laterite, agitation leaching, iron precipitation step, and nickel-cobalt solvent extraction. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：Taixi oxidized coal surface has many hydrophilic functional groups as well as many cracks and holes. The effect of prewetting time on the flotation behavior of Taixi oxidized coal had been observed in our previous studies, and it was surmised that the oxidized coal surface was easier wrapped by water shell because the hydrophilic functional groups could be bonded with water through hydrogen bond and the cracks and holes could also be filled up with water when the coal was prewetted in the flotation cell. However, the mechanism of how the prewetting/immersion process can affect the flotation performance of Taixi oxidized coal is still poorly understood and should be investigated clearly. This paper was to conduct the fundamental studies on the effect of prewetting/immersion time in the attachment time between air bubble and Taixi oxidized coal. It was found that the attachment time increased quickly with the increase of prewetting/immersion time. The micro-bubbles are produced on the oxidized coal surface when the coal particles are immersed in the water. The micro-bubbles may be primarily from the air entrapped in the cracks and holes on the oxidized coal surface. As the prewetting/immersion time increased, the micro-bubbles would dissolve and get away from coal surface, and then the cracks and holes would be fully filled up with the water. Finally, the oxidized coal surface would be wrapped by a thick hydration shell which could prevent the oxidized coal surface from being attached by the bubbles, and hence the bubble-coal attachment time increases with the increase of prewetting/immersion time. (C) 2017 Elsevier B.V. All rights reserved.
Liu, FupengLiu, ZhihongLi, YuhuWilson, Benjamin P....
10页
查看更多>>摘要：A new oxalic acid (H2C2O4) and hydrogen peroxide (H2O2) based extraction process was developed to recover valuable metals - in particular Ga and Ge - from the zinc refinery residues. H2C2O4 and H2O2 leaching studies indicated that the selective leaching of metals in the residues, that primarily contain Zn, Cu, Fe, SiO2, Ga and Ge, can be achieved. Under the optimal leaching conditions ([H2C2O4] = 110 g/L, [H2O2] = 0.12 mol/L, L/S ratio = 8, T = 40 C-omicron and t = 30 min), 9932% of the Ga, 98.86% of the Ge and 30.25% of the Fe were leached out, whereas the leaching of Zn, Cu and Si only reached 0.30%, 0.82% and 0.43%, respectively. Concerning leachate purification, 98.31% of the iron could be removed in the form of FeC2O4.2H(2)O with minor losses of Ga and Ge (1.08% and 0.68%) using an ultrasound-assisted iron powder replacement method under optimal conditions. The Ga (99.36%) and Ge (99.89%) were subsequently extracted by tri(octyl-decyl)amine (N235). After extraction, the loaded organic phase was stripped of Ga (98.91%) and Ge (99.21%) into separate solutions using sequential treatments of 2 mol/L H2SO4 and 4 mol/L NaOH respectively. Based on these results, a process flow sheet of efficient separation and recovery of Ga and Ge is presented. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：Eight anthracite granule species used as filter media were tested for organic phase separation from copper electrolyte in a filter bed. The effects of filter bed depth and fluid velocity were studied. The macro porosity, density, surface area, bed expansion, pressure loss during backwash, mechanical strength, surface micro porosity and morphology of the anthracite species were analyzed. The organic droplet average diameter and zeta potential of the electrolyte suspension were also measured. In addition, SEM analysis was used to investigate aging and separation performance of filter media. For the different anthracite species, the aging and a similar separation performance were found. However, some variation in performance was detected during backwash experiments. Pilot scale runs with inversed flow indicated that testing of the anthracite species before selection is advantageous. (C) 2017 Published by Elsevier B.V.
查看更多>>摘要：A critical parameter in the design of pastefill distribution systems is the shear yield stress of the backfill. Yield stress is used in the hydraulic modelling to estimate the friction losses in the system and is generally assumed to be constant throughout the piping system. However, many sites report a change in slump during transport - sometimes up to 50 mm. As slump is used as an indicator of yield stress, it can be hypothesized that that material rheology is changing during transport potentially due to changes in particle shape and size or pastefill temperature. By sampling pastefill at the surface and at the discharge point underground, in two Canadian mines, this study shows that the yield stress and temperature of pastefill does not remain constant through the distribution system. The size and shape of the backfill particles are analyzed and no remarkable changes are found. The effect of temperature on the yield stress is investigated through laboratory testing using slump tests and a rotational viscometer and indicate that temperature is a significant factor in the yield stress change. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：Utilization of N-carboxymethyl chitosan (N-CMCh) to limit the detrimental effect of serpentine on the flotation of pyrite is presented in this work. Flotation results show that the presence of hydrophilic serpentine slimes results in lower recoveries of the valuable pyrite. Utilization of N-carboxymethyl chitosan can limit the detrimental effect of serpentine on the flotation of pyrite. Zeta potential measurements illustrate that N-CMCh is with negative charge and the electrostatic interaction between serpentine and N-CMCh is occurred at pH 8.5, then the serpentine zeta potential will be changed from positive to negative, the electro-steric attraction converts into electro-steric repulsion between pyrite and serpentine and the pyrite recovery is improved. (C) 2017 Elsevier B.V. All rights reserved.
Tao You-junSun Qi-xiaoMan Zhong-peiZhu Xiang-nan...
7页
查看更多>>摘要：Enrichment and migration regularity of coal particles in compound force field provided by Falcon concentrator were studied. Influence of centrifugal force and fluidization water pressure on the distribution rates and ash contents of materials that enriched in overflow, top separation area and bottom separation area were tested respectively. Radial velocity of fluidization water, having an important influence on the sedimentation of particles, was calculated and results show that radial velocity of fluidization water in top groove is greater than that in bottom groove, which contributed to the selectivity and recovery of combustible. Besides, density composition of products in different enrichment areas was studied. Results show that in the upward migration process, particles with high density are gradually captured. Therefore, the material density is gradually reduced from bottom to top separation area. Meanwhile, mismatch phenomena occurred as the existence of heavy particles in overflow, and light particles in the grooves. Based on the morphology analysis, it is can be deduced that particles mismatch is the results of the increase of drag coefficient since the irregular shape. (C) 2017 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, response surface methodology (RSM) and artificial neural network (ANN) were used to develop an approach to analyze the behavior of different process variables such as pulp density, oil dosage, agglomeration time, and particle size, which affects the coal oil agglomeration process using Linseed oil as a bridging liquid. The investigation was done using Box-Behnken design (BBD) of response surface methodology, the same design of experimental data was used in training with the artificial neural network, and the results obtained from the two methodologies were compared. The ANN model predicted responses with better accuracy with coefficient of determination (R-2) 0.97 and 0.95 for % ash rejection and % organic matter recovery respectively in comparison to RSM-BBD R-2 of 0.97 and 0.92 for % ash rejection and % organic matter recovery respectively. The optimal condition established for the high % ash rejection and % organic matter recovery were pulp density (3.002%), oil dosage (15%), agglomeration time (15 min), particle size (0.168 mm) with predicted % ash rejection and % organic matter recovery as 68.00% and 95.24% respectively, with the desirability of 96.90%. The proposed optimal conditions were examined in the laboratory and the % ash rejection and % organic matter recovery achieved as 64.60% and 93.93 respectively. (C) 2017 Elsevier B.V. All rights reserved.
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