查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0065" view="all">In this paper, in order to study the interaction mechanism of non-polar oil assisted dodecylamine (DDA) flotation of quartz, the particle-oil drops system were treated the same as the hydrophobic particles system. Pure dodecane was chosen as research object, the interfacial interactions between quartz particle and oil drop were investigated through calculation of the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) potential energy profile. Based on the calculations of the van der Waals attractive interaction potential, hydrophobic interaction potential, hydrocarbon chain association potential, and electrostatic interaction potential, the results indicated that the mineral particle and oil drop attachment state was mainly dominated by hydrophobic interaction potential. In the modification of oil agglomeration flotation process, the adsorption of DDA on the dodecane/water interface presented significant effects on the interfacial interactions between quartz particle and oil drop. It was found that the adsorption of DDA at dodecane/water interface changed the zeta potential value of oil drop from negative to positive. In this case, the attachment of the particles would occur spontaneously, which was due to the contribution of electric double layer attractive interaction. On the contrary, in the traditional oil agglomeration flotation process, a mechanical agitation was required to overcome a potential barrier due to the existence of electric double layer repulsive interaction between the negatively charged oil drops and mineral particles. This study was focus on the theoretical level, and provided some insights into mechanism of oil agglomeration flotation.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0075" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Mineral particle and oil drop attachment state was dominated by hydrophobic interaction potential.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">In the modification of oil agglomeration flotation process, the attachment of the particles occurred spontaneously.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Interaction of modified dodecane with quartz was intensified by electrostatic forces.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
Slam I.Y. SalamehFawwaz I. KhaliliAmmar H. Al-Dujaili
10页
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0095" view="all">Raw and organically modified diatomaceous earth were used to remove U(VI) and Th(IV) ions from aqueous solution using the batch method. Effects of contact times, dosage of adsorbent, pH, ionic strength and temperature on the adsorption process were studied. The results indicated that the adsorption of these ions was affected by pH and ionic strength. The adsorption isotherms fit the Langmuir, Freundlich and D–R models at different temperature. The kinetic results revealed that pseudo-second-order kinetic model provided the best description of the equilibrium data. Thermodynamic parameters showed the adsorption process was spontaneous and endothermic. The best recovery for U(VI) was obtained when 1.0M EDTA was used as eluent, while for Th(IV) ions when 1.0M HNO<ce:inf loc="post">3</ce:inf>was used.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0100" view="all">This paper presents the uptake of U(VI) and Th(IV) ions from aqueous solutions by raw and organically modified diatomaceous earth.</ce:simple-para><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0105" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Raw and organomodified diatomaceous earth (DT-HDTMA) was utilized as an adsorbent.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">It was used for the removal of U(VI) and Th(IV) from aqueous solutions.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Adsorption was well described by the Langmuir, Freundlich and D-R isotherm models.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Adsorption kinetics of these ions was found to conform to pseudo-second order model.</ce:para></ce:list-item><ce:list-item id="li0025"><ce:label>?</ce:label><ce:para id="p0025" view="all">The adsorption of U(VI) and Th(IV) on (DT-HDTMA) is endothermic and spontaneous.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0055" view="all">Surface roughness plays an important role in the floatability and wettability of mineral and coal particles. However, the role of surface roughness in the floatability of coal particles has not been sufficiently investigated because coal consists of organic and inorganic materials. This paper is to obtain some insights into the role of surface roughness in the coal surface wettability. In this investigation, Taixi ultra-low-ash coal particles, with ash content of 1.55%, were polished and the polished flat coal surfaces with various roughness were obtained. The attachment time between air bubble and flat coal surface were tested at the water solution without flotation reagents. Throughout this paper, it was found that the attachment time increased with the increase of roughness of coal surface. The attachment area between bubble and flat coal surface was decreased with the increase of surface roughness. The attachment between bubble and flat rough coal surface was unstable, compared to the attachment between bubble and smooth coal surface. The rougher coal surface makes the detachment between bubble and coal surface easier than the smoother coal surface. The higher the roughness of coal surface is, the more pores and grooves the coal surface has. The pores, gaps and grooves are filled up with the water in the slurry and have negative effects on the attachment between bubble and flat coal surface.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0060" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Bubble-coal attachment time increased with the increasing surface roughness.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">Bubble-coal attachment is unstable at rough coal surface.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Bubble-coal attachment is stable at smooth coal surface.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Adhesion area between bubble and coal is very large at smooth surface.</ce:para></ce:list-item><ce:list-item id="li0025"><ce:label>?</ce:label><ce:para id="p0025" view="all">Adhesion area between bubble and coal is very small at rough surface.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0085" view="all">It is well accepted that non-polar oils can be used as collector extender in oil agglomeration flotation of many different types of mineral. In this paper, in order to study the influences of oil structures on the non-polar oil assisted dodecylamine (DDA) flotation of quartz, the research focuses on the interaction of DDA (collector) and non-polar oil (collector extender) in aqueous phase. In this work, saturated hydrocarbon dodecane and cyclohexane, unsaturated hydrocarbon dodecene, aromatic hydrocarbon dimethylbenzene and 1-methylnaphthalene were chosen as researched subjects, and the influences of oil structures on interfacial activity of oil–DDA–water ternary models were investigated by experimental and theoretical methods. The flotation results demonstrated that the collecting capability of the oil and DDA combination follows the order of 1-methylnaphthalene>dimethylbenzene>dodecene>cyclohexane>dodecane. Moreover, molecular dynamic (MD) simulation is performed to investigate the interfacial property of these five non-polar oil-DDA-water systems, and five parameters, radial distribution functions, interaction energy, density distribution, interfacial thickness and self-diffusion coefficient are proposed to reveal the influence mechanism of molecular structure on interfacial activity of the ternary oil-DDA-water systems. The same trends are obtained from the parameters described above, aromatic hydrocarbon dimethylbenzene and 1-methylnaphthalene performance better than saturate hydrocarbon and unsaturated hydrocarbon. The researched results indicate the interaction between non-polar oil and DDA hydrophobic alkyl tail would enhance the mobility of oil component, which induce significant change of interfacial thickness and diffusivity. Additionally, the interaction between DDA hydrophilic head group and water molecules via strong hydrogen bonds, van der Waals interactions and weak electrostatic attraction would lead to water molecules penetrate through DDA monolayer and adsorb on oil surface. The researches enable us to obtain a deeper microscopic-level understanding of the interaction between oil-DDA-water ternary components, and maybe have some references for designing of oil-assisted flotation agent.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0095" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Aromatic hydrocarbon dimethylbenzene and 1-methylnaphthalene performance better than saturate hydrocarbon and unsaturated hydrocarbon used as collector extender.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">Interaction between non-polar oil and DDA alkyl tail would enhance the mobility of oil component.</ce:para></ce:list-item><ce:list-item id="li1010"><ce:label>?</ce:label><ce:para id="p1010" view="all">Interaction between DDA head group and water molecules would enhance the mobility of water component.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0025" view="all">A protocol based on peroxide fusion has been developed for the determination of Au in metallurgical samples and ores covering a wide range of concentrations and diverse mineralogies. The quantity of Na<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">2</ce:inf>required was minimised, while maintaining lixiviant efficacy, by the use of mixed NaOH + Na<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">2</ce:inf>fluxes. The method was shown to be particularly applicable to the determination of coarsely-particulate gold. Fusion cakes were dissolved in hydrochloric acid and then extracted using methylisobutylketone to provide concentrations appropriate for quantification by graphite furnace atomic absorption spectroscopy and to minimise interferences from dissolved salts. The protocol was tested on a variety of certified reference materials and produced results in excellent agreement (at Au concentrations ranging from 0.05 to 47μgg<ce:sup loc="post">?1</ce:sup>) with the traditional lead fire assay method, while avoiding the health and safety issues associated with that technique.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0030" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Peroxide fusion GFAAS method suitable for routine commercial lab analysis developed</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">Results comparable to Pb fire assay over wide range of mineralogy and concentration</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Potential for gold losses critically evaluated and found to be minimal.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Addition of NaOH significantly reduces amount of Na<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">2</ce:inf>required.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0055" view="all">World reserves of bauxite include vast quantities of ore which are sub-economic due to high levels of reactive silica. It would lead to the substantial loss of caustic soda during Bayer processing. With the gradual reduction of the economic reserves of high-grade ore, people began to focus on the desiliconization treatment of the low-grade ore at reasonable cost. Biodesilication by silicate bacteria (such as<ce:italic>Paenibacillus mucilaginosus</ce:italic>) has been known as a potential technology for its characteristics of environmental protection, energy saving and sustainable development. In this paper, one silicate bacterial isolate with high desilication ability was screened, identified, and named as<ce:italic>Paenibacillus mucilaginosus</ce:italic>BM-4. The optimum cultural pH and temperature of BM-4 were also determined experimentally as 8.0 and 30°C, respectively. Under these optimum cultural conditions, silicate ores were bioleached by BM-4. It seems that the stratified structures silicate ores, such as kaolinite and chlorite, were more readily to be leached by BM-4.</ce:simple-para><ce:simple-para id="sp0060" view="all">On the other hand, the float-abilities of BM-4 on kaolinite and bauxite were also investigated. With the experimental results shown that there existed the electrostatic adsorption process between BM-4 and kaolinite, and the Langmuir isotherm adsorption process between BM-4 and bauxite. It was observed that the float-abilities of bauxite were significantly depressed by BM-4, while the those of kaolinite were enhanced. The bioflotation test of the mixture of bauxite and kaolinite (mass ratio 5:1) through BM-4 were carried out by a modified Hallimond tube. With results shown that the Al/Si ratios of this mixed minerals were improved from 3.05 to 8.60 after bacterial conditioning due to bauxite depression. Eventually, 83.0% of Al<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">3</ce:inf>were recovered from the mixed minerals by BM-4.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0065" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">High desilication efficiency was existed for the layer crystal structures materials by<ce:italic>Paenibacillus mucilaginosus</ce:italic>BM-4.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">The Al/Si ratio was improved through bioflotation of mixed minerals by<ce:italic>Paenibacillus mucilaginosus</ce:italic>BM-4.</ce:para></ce:list-item><ce:list-item id="li1015"><ce:label>?</ce:label><ce:para id="p1015" view="all">There exists the electrostatic adsorption process of<ce:italic>Paenibacillus mucilaginosus</ce:italic>BM-4 on kaolinite.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">There exists the Langmuir isotherm adsorption process of<ce:italic>Paenibacillus mucilaginosus</ce:italic>BM-4 on bauxite.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0060" view="all">High gradient magnetic separation (HGMS) has been an effective method for the concentration or removal of fine para-magnetic particles from suspension, but its powerful magnetic capture to magnetic particles results in the mechanical entrainment of non-magnetic particles in magnetic product, and thus reduces the separation selectivity. HGMS in centrifugal field (CHGMS) is proposed to improve the separation selectivity, and in this investigation a cyclic pilot-scale CHGMS separator was used to concentrate fine ilmenites from slurry. The theoretical descriptions on this CHGMS process indicate that the introduction of centrifugal field in the HGMS field has a promoting effect on the magnetic capture of matrix to magnetic particles and significantly improves the HGMS performance, and a minimum critical magnetic field force is required for the capture of magnetic particles in the centrifugal field. These theoretical descriptions were experimentally verified and the dependence of CHGMS performance on the key parameters such as centrifugal acceleration was determined. This CHGMS method has achieved a significantly improved separation selectivity and performance to the fine ilmenite, and thus provided a potential prospect in the development of CHGMS technology.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0065" view="all">CHGMS process (left) and forces acting upon a para-magnetic particle (right).</ce:simple-para><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0070" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">The introduction of centrifugal force in HGMS field improves separation selectivity.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">The matrix rotation improves capture probability and recovery for magnetic particles.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Centrifugal HGMS achieves an improved separation performance for fine ilmenite.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Centrifugal HGMS presents a new method for separation of para-magnetic minerals.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0160" view="all">This study explored the processing of chalcopyrite ore through heap leaching followed by flotation. Crushed and agglomerated chalcopyrite ore was subjected to bacterially-assisted leaching at ambient temperature in columns that ranged in height from 1m to 5m. >50% extraction was obtained after 16months. Chalcopyrite leaching was affected only by time, not irrigation rate, acid delivery rate, or column height. This indicated that chalcopyrite heap leaching was reaction-limited rather than transport-limited, and therefore relatively impervious to scale. The findings suggest that chalcopyrite could be leached in substantially taller heaps, releasing proportionally greater quantities of copper, without sacrificing recovery. Leaching of the chalcopyrite ore had little effect on its floatability, as indicated by rougher flotation testing. The maximum flotation recoveries,<ce:italic>R</ce:italic><ce:inf loc="post">MAX</ce:inf>, were 90% and 88% for the ore and leached residues, respectively. The combined leach/float recoveries were greater than the individual copper recoveries from leaching and flotation alone. This was simply due to the initial leaching step recovering some of the copper that would have been inevitably lost to flotation tailings. Such a leach/float approach may actually benefit from the low reactivity of chalcopyrite, which ensures that leaching would never be so extensive as to affect the later floatability of the mineral.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0145" view="all">The paper presents strategies for control of parallel gravitational coal separation processes in dense media vessels and jigs. These strategies are designed to maximize the yield of the final product at the desired ash content. The principle of circuits operating in parallel at equal incremental ash contents has been discussed from the point of view of its practical application. In the case of an ideal separation process this principle can be reduced to the requirement of equal separation densities for parallel circuits; so far, however, it has not been applied in real industrial processes. The paper includes a discussion on the concept of a separation density and incremental ash for computer simulation of parallel processes and their control. Conclusions from this discussion, presented in the paper are not available in open literature especially as regards the optimal control of jigs operating in parallel: (a) the separation density (elementary ash) defined as the density of the feed fraction reporting in half to the concentrate and in half to refuse and incremental ash (density of the elementary mass of material recovered in a process in which the yield is increased by an infinitesimally small amount) can be used for real time control in dense media baths and in jigs; (b) the autogenous separation process in jigs makes it possible to determine the incremental ash as the ash content in the separation layer of the material as measured by the correlation between ash content and the density of the separation layer. The concept of a new control system which may be used in practice, based on a radiometric density meter with a properly collimated radiation beam and located at the level of the separation layer has been discussed. The radiometric density meters, applied to monitor the density of the separation layer in jigs on-line and to monitor the density of heavy media in dense media baths can be used effectively in real-time control systems optimizing the yield of product.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0150" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">The density of the separation layer is the main control variable in a jig.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">The density of dense media is the main control parameter in heavy media systems.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Both densities can be measured by radiometric density meters.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Maximum product yield in parallel systems is obtained for equal control variables.</ce:para></ce:list-item><ce:list-item id="li0025"><ce:label>?</ce:label><ce:para id="p0025" view="all">Optimal real-time control is feasible with the use of radiometric density meters.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
Valentina InnocenziIda De MichelisFrancesco FerellaFrancesco Vegliò...
11页
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0095" view="all">In this paper, leaching kinetics of yttrium from cathode ray tubes in sulphuric acid and hydrogen peroxide solution was investigated. It was found that hydrogen peroxide concentration, followed by temperature, has the greatest influence on leaching rate. Leaching rate is clearly enhanced by the increase in H<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">2</ce:inf>concentration. The leaching process without hydrogen peroxide follows the kinetic model controlled by the chemical regime, whereas in presence of H<ce:inf loc="post">2</ce:inf>O<ce:inf loc="post">2</ce:inf>it follows the kinetic model controlled by diffusion through the product layer. The apparent activation energy was determined to be 40.0kJ/mol and 90.3kJ/mol with and without hydrogen peroxide in solution, respectively. Moreover, the experimental data were used to describe empirical mathematical models in order to predict the yttrium extraction as a function of sulphuric acid concentration, hydrogen peroxide concentration, temperature and time. From the analysis of the results and models, the optimal conditions to maximize the extraction of yttrium were inferred: 40°C, 10%vol hydrogen peroxide, 15min of reaction with 15%wt/vol pulp density, or alternatively at higher temperature (80°C) 15%wt/vol pulp density, 120–180min with 0% or 5%vol hydrogen peroxide in solution. Hence, yttrium is easily leached from CRTs powder at low temperature (40°C) with higher concentration of hydrogen peroxide, or by means of higher temperature (80°C) and lower concentration, even null, of hydrogen peroxide.</ce:simple-para></ce:abstract-sec></ce:abstract>]]>
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