外文翻譯--在自軋機(jī)上用三維離散元法測定升降的布局速度和填充效果（英文）

1、Determination of lifter design, speed and filling effects in AG mills by 3D DEMN. Djordjevic *, F.N. Shi, R. MorrisonJulius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane 4068, AustraliaRece

2、ived 28 April 2004; accepted 1 June 2004AbstractThe power required to operate large gyratory mills often exceeds 10MW. Hence, optimisation of the power consumption will have a significant impact on the overall economic p

3、erformance and environmental impact of the mineral processing plant. In most of the published models of tumbling mills (e.g. [Morrell, S., 1996. Power draw of wet tumbling mills and its relationship to charge dynamics, P

4、art 2: An empirical approach to modelling of mill power draw. Trans. Inst. Mining Metall. (Section C: Mineral Process- ing Ext. Metall.) 105, C54–C62. Austin, L.G., 1990. A mill power equation for SAG mills. Miner. Metal

5、l. Process. 57–62]), the effect of lifter design and its interaction with mill speed and filling are not incorporated. Recent experience suggests that there is an oppor- tunity for improving grinding efficiency by choosi

6、ng the appropriate combination of these variables. However, it is difficult to exper- imentally determine the interactions of these variables in a full scale mill. Although some work has recently been published using DEM

7、 simulations, it was basically limited to 2D. The discrete element code, Particle Flow Code 3D (PFC3D), has been used in this work to model the effects of lifter height (5– 25cm) and mill speed (50–90% of critical) on th

8、e power draw and frequency distribution of specific energy (J/kg) of normal impacts in a 5m diameter autogenous (AG) mill. It was found that the distribution of the impact energy is affected by the number of lifters, lif

9、ter height, mill speed and mill filling. Interactions of lifter design, mill speed and mill filling are demonstrated through three dimensional distinct element methods (3D DEM) modelling. The intensity of the induced str

10、esses (shear and normal) on lifters, and hence the lifter wear, is also simulated. ? 2004 Elsevier Ltd. All rights reserved.Keywords: Comminution; Grinding; Modelling; DEM1. IntroductionThe power required to operate larg

11、e mills often ex- ceeds 10MW. Therefore, optimisation of the power uti- lisation will have a significant impact on the overall economic performance and environmental impact of the mineral processing plant. Recent experie

12、nce suggests that there is an opportunity for improving grinding effi-ciency by choosing the appropriate combination of mill speed, filling and lifter design. However, it is difficult to experimentally determine the inte

13、ractions of these varia- bles in a full scale mill. The discrete element method (DEM) has been proved to be a useful tool in milling simulation and optimisa- tion. A number of papers have been published in the lit- eratu

14、re by using DEM in modelling and simulation of comminution devices, majority of them being limited in 2D. Hlungwani et al. (2003) used a 2D laboratory ball mill to validate the DEM modelling of liner profile and mill spe

15、ed effects. Cleary (1998, 2001) used DEM to investigate charge behaviour and power consumption0892-6875/$ - see front matter ? 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2004.06.033* Corresponding autho

16、r. Present address: JKMRC, Isles Road, Indooroopilly 4096, Australia. Tel.: +61 7 3365 5888; fax: +61 7 3365 5999. E-mail address: n.djordjevic@uq.edu.au (N. Djordjevic).This article is also available online at: www.else

17、vier.com/locate/minengMinerals Engineering 17 (2004) 1135–1142of the lifters varied between 5 and 25cm. For each lifter geometry, the rotational velocity of the mill was varied in the range 50–90% of critical speed. In o

18、rder to determine the effect of lifters and mill speed on the effective power draw of the mill it is neces- sary to determine the power draw without any lifting ac- tion first. This can be achieved by calculation of the

19、no-lifters power with a coefficient of friction being set to nil. It is possible that in such a case, power draw will be minimal or nil, due to the symmetric shape of the charge around the vertical axis of the mill, Fig.

20、 1.The second phase includes introduction of the mill friction. The third phase includes introduction of lifters of constant width and number, but of different height. For each lifter height power draws at different mill

21、 speeds were determined. By comparing modelled power draws with those of the no-lifter mill, the effect of each new variable of mill design and operating conditions can be determined. In the simulations normal and shear

22、stiffness of the particles were set 1 · 105N/m and density 2650kg/m3. The power draw of the mill comprises the power con- sumed in rotating the empty mill (no-load power), to abrade the charge without lifting the pa

23、rticles, and to lift the charge which may eventually result in impact break- age. Note that this is not the same as the no-load power in a real mill which requires energy to overcome friction in bearing and losses within

24、 mill motor. In the case of mill without lifters and in which the coefficient of friction is set to zero, the power draw of the real mill is only a form of no-load power. There is no power being transferred to the charge

25、. The essential role of lifters is highlighted by the fact that without them there would be essentially no net-power draw (assumingFig. 2. Charge shapes for the mill with lifters of various heights, all with a coefficien

26、t of friction 0.3: (a) no-lifter, (b) 5cm lifters, (c) 10cm lifters, (d) 15cm lifters, (e) 20cm lifters, and (f) 25cm lifters.Table 1 Particle size distribution of the modelled mill chargeParticle diameter (mm) Number of