文献翻译-矿石在电气粉碎中选择性破碎的实验和数值研究.doc

1、翻译部分英文原文Experimental and numerical studies of selective fragmentation of mineral ores inelectrical comminutionAbstract:An experiment was conducted in which two sulphide ores and one platinum ore were each subjected to highvoltage pulses and mechanical breakage, with the same specific energy input, i

2、n order to compare themineral modal abundance and grade in the two comminution products. The data from this experiment haveprovided unambiguous evidence of greater enrichment of the minerals with high conductivity/permittivity inthe less than 0.3 mm size fractions of the electrical comminution produ

3、ct. Numerical simulations using COULOMB 3Dindicated thatwith the existence of an electrical potential difference in the system, a high electricalfield intensity was created around the boundary of the minerals with high conductivity/permittivity, causingselective fragmentation, thereby elucidating an

4、d supporting the experimental findings.Keywords:High voltage pulse breakage;Energy efficiency;Selective fragmentation;Numerical simulation1. Introduction World consumption of minerals is on the increase and this trend is likely to continue. However, the depletion of many high grade ore reserves is l

5、eading to an increased need to process ores of lower grade. To liberate the valuable minerals from such ores requires fine grinding, a processwhich demands higher energy requirements and yields lower energy efficiencies. Addressing this comminution dilemma has become a major focus for themineral ind

6、ustry. Consequently, improvements in rock breaking and mineral liberation techniques which can reduce energy consumption and improve metal production processing arebeing sought to address this challenge。 The specific liberation process, such as the disintegration of oresby high voltage pulses, has b

7、een suggested as a possible route bywhich mineral liberation properties can be enhanced, relative to conventional breakage methods (Andres, 1977; Anon, 1986). In the technology of electrical disintegration, the process of liberation of minerals is determined by the locality of the split between diff

8、erent minerals along the boundaries. The ore fragments are immersed in a dielectric liquid (usually tap water) and experience high voltage pulse discharges, inducing the explosive breakdown of solids. The explosive breakdown is a result of plasma streamers occurring along the boundaries of minerals

9、with different electrical conductivity and permittivity. Andres reported a number of comparative studies on the comminution products of variousmineral ores, including an apatite nepheline ore (Andres, 1977), diamonds that were liberated by high voltage pulses,without a single mechanical defect, that

10、 were cleanly detached from kimberlitic matrices (Andres, 1994), oxide ores containing hematite and PGM, and sulphide ores containing complex Cu sulphides and pentlandite (Andres et al., 2001a). All these results indicated that electrical pulses generated a higher percentage of liberated particles a

11、nd a lower percentage of fine material than those obtained by mechanical comminution. Lastra et al. (2003) showed, in a comparative liberation study on a Merensky reef sample (comminuted by electrical pulse disaggregation and by conventional crushing) that the liberation of gangue was similar using

12、eithermethod, but the liberation of chromite, pentlandite, pyrrhotite and PGMwas higherwith electrical pulse disaggregation than with a conventional jaw crusher. Ito et al. (2009) found that electrical disintegration resulted in preferential breakage of coal substances and mineral particles along th

13、eir boundaries. High voltage pulse fragmentation is also used in geological application; with the advantage of allowing the liberation of minerals along the natural grain boundaries and existing deep fractures, without the unnecessary breakage of particles: a condition not achievablewith conventiona

14、l breakage methods. Chernet (2010) reported the use of high voltage pulses to release individual grains of gold, electrum and other minerals of interest, preserving their original texture, shape and size for detailed study of their morphology, surfacial features, grain size and composition. SelFrag

15、(2008) showed an example of the selective fragmentation of a granite complete liberation and the recovery ofmorphological intact zircons and radiolarian chert. In recycling building materials, crushing concrete material with a multistage crusher or mill cannot separate the constituents, and the proc

16、ess also produces a large proportion of dust and small particles. However, high voltage pulses can break concrete along the boundary of the different constituents and recover sand, gravel and cementseparately. The cement fraction can be baked to produce cement clinker All of these examples, reported in the literature, suggest that there is a mechanism of selective fragmentation happening during the high voltage pulse process. However, rec