Comparison of energy efficiency between ball mills and stirred mills in coarse grinding

Shi, Fengnian; Morrison, Rob; Cervellin, Andrew; Burns, F.; Musa, F.

doi:10.1016/j.mineng.2008.12.002

Cited by 66 publications

(19 citation statements)

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“…During stages 1 and 2, impact breaking tests to determine the A*b ranking parameter were conducted pre and post-blast. The rotary breakage test (RBT) described by Shi et al (2009) was used for this purpose. The test operates by throwing a set of individual fragments at a known velocity against the walls of a cylindrical device.…”

Section: Methodsmentioning

confidence: 99%

Effect of blast-induced fragment conditioning on impact breakage strength

Parra

Onederra

Michaux³

2014

Mining Technology

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This paper presents the results of controlled blasting experiments and blast modelling carried out to understand and quantify the effect of blasting on the creation of fractures inside fragments referred to as conditioning. Fragment conditioning is studied through the use of indirect and direct measurement techniques on samples collected from different zones around an explosive charge. Modelling is used to map different levels of conditioning throughout the blasted samples and explore the impact of boundary conditions on the spatial distribution of conditioning levels. Combined statistical analysis of repeatable tests showed that the measured impact breakage ranking parameter (A*b) increased by 20 and 33% within the low and intermediate conditioning zones respectively. This translates into a statistically significant strength reduction of the material. These results in conjunction with other documented experience suggest that blast-induced conditioning can have a positive impact on comminution performance and thus energy consumption. Results from this work provide the basis for a methodology to better define postblast breakage strength inputs into comminution performance models; as well as a preliminary approach to scale up the extent and degree of conditioning by blasting. Further work is required to evaluate the ability to control the degree of conditioning through the application of improvements in designs and novel blasting technology

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Section: Methodsmentioning

confidence: 99%

Effect of blast-induced fragment conditioning on impact breakage strength

Parra

Onederra

Michaux³

2014

Mining Technology

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“…Specifically, Shi et al (2009) have shown that an Isamill (as a horizontally stirred mill) at least at laboratory scale exhibited better grinding efficiency for fine grinding (product less than 40 lm) compared to other (vertical) mills (such as ball and tower mills). In contrast, for coarse grinding they showed that the ball mill was more efficient than the Isamill with fine feed.…”

Section: Introductionmentioning

confidence: 99%

Computational prediction of performance for a full scale Isamill: Part 1 – Media motion and energy utilisation in a dry mill

Cleary

Sinnott

Pereira

2015

Minerals Engineering

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“…... 16 Figure 2.9 -Effect of impeller speed in the stirred mill (Zheng et al, 1996) .17 -(a) Breakage distribution function versus relative particle size (b) Reduced specific rate of breakage and apparent reduced specific rate of breakage versus particle size for copper concentrate batch test in a 6.6 liter Tower Mill (Menacho and Reyes, 1989 Figure 2.18 -Error associated with power scale-up method proposed by Morrell et al (1993) for (a) Tower Mill (b) pin mill (Jankovic, 1999) Tables Table 2.1 -Common gravity induced and fluidized stirred mills and their main features (after (Allen, 2013), (Davey, 2006), (Rahal et al, 2011), (Shi et al, 2009), (Lehto et al, 2013) Table 2.4 -Media cost and consumption rate for stirred mill (after Lichter and Davey, 2006 Mannheim (2011) Table 2.9 -Test conditions described by Stehr et al (1987) Table 2.10 -Breakage parameters developed for a pilot Vertimill test work using the Austin Characterization Procedure (Mazzinghy et al, 2015a) Table 5.2 -% new generation of -75μm in different operating conditions for Cu-Au ore and limestone ..... 100 Table 5 …”

Section: List Of Figuresmentioning

confidence: 99%

“…These have grinding discs mounted on a horizontal shaft connected to a motor via a gear box. The tip speed of the rotating discs is around 21-23 m/s (Shi et al, 2009), and it imparts intense agitation of the media. In general, ceramic beads are used as grinding media in the IsaMill; however, sand is occasionally used too as grinding media.…”

Section: Stirred Mills Classification and Descriptionmentioning

confidence: 99%

“…Energy rises exponentially to grind particles below 75 µm, and 45 µm to 40 µm is the practical limit of the ball product size (Morrell et al, 1993). Shi et al (2009) showed an average of 30% energy savings when using the stirred mill compared to the ball mill in the coarse grinding with feed sizes ranging from 3.35 mm to 150 µm and product P80 sizes less than 100 µm.…”

Section: Introductionmentioning

confidence: 99%

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Process modelling of gravity induced stirred mills

Hasan¹

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Fine grinding is becoming an integral part of mineral processing plants to liberate valuable minerals from fine-grained low-grade ore bodies. Stirred mills are becoming recognized by the industry as a more efficient technology selection compared to the ball mill for fine grinding (< 100 µm). The increasing number of stirred mill installations in mineral processing concentrators has necessitated a process model development that enables full circuit modelling and simulation. Many researchers have developed mathematical models to assist in the design and optimization of the stirred mill operation including gravity induced stirred mills such as the Metso Vertimill and the Nippon Eirich Tower Mill.Most of the developed models lack sufficient responses to changes in process conditions. Furthermore, there is an internal classification effect that is previously mentioned in several publications but was not quantified through experiments. Therefore, a research program was designed and carried out to describe and model different sub-processes related to the operation of the gravity induced stirred mill. The sub-process models (i.e. grinding and internal classification) were combined into a single model structure to represent the operation in a gravity induced stirred mill.During this research, comprehensive test work was carried out in a batch gravity induced stirred mill using Cu-Au ore and limestone to evaluate the effect of operating conditions (i.e. specific energy consumption, slurry density, grinding media size and stirrer tip speed) on particle size and fines generation (-75μm). The test data showed a finer product size when the mill operates at higher specific energy, lower slurry density, smaller grinding media size and higher stirrer tip speed. The test work also identified that attrition breakage mechanism is predominant in the gravity induced mill. Sub-process models that relate the selection function to the process operating conditions were developed. The internal classification effect on mill operation was also measured through test work by using industrial grade silica to identify its effect on the mill operation. The result showed that particle classification takes place inside the gravity induced mill in certain favorable conditions. Models were developed to link the classification parameters and the mill operating conditions to be included in the combined model structure.ii A process model (using a time-based population balance technique) was developed, integrating individual sub-processes models such as breakage, selection and classification functions. The model was validated with industry survey data in different process conditions. The validation result showed that the developed model was capable to predict the mill product size distribution when mill power, feed rate, slurry solids concentration and grinding media size are varied.The thesis has successfully developed a process model of the gravity induced stirred mill with predictive capability. Moreover, it has developed an in-depth understa...

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Comparison of energy efficiency between ball mills and stirred mills in coarse grinding

Cited by 66 publications

References 4 publications

Effect of blast-induced fragment conditioning on impact breakage strength

Effect of blast-induced fragment conditioning on impact breakage strength

Computational prediction of performance for a full scale Isamill: Part 1 – Media motion and energy utilisation in a dry mill

Process modelling of gravity induced stirred mills

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