Effects of Fragmentation Size Distribution on Truck- ... With 'Mine to Mill' concept, the focus has shifted whereby blasting practices are modified to achieve energy optimization in all downstream activities. Blasting is now designed to increase load and haul productivity and ensure mill feed ... came out with three observations; first, ore ...
Chapter 5 Effect of ball size distribution on milling kinetics 62 5.1 Introduction 62 5.2 Selection function of ball mixtures 63 5.2.1 Equilibrium ball size distribution 63 5.2.2 Original equipment manufacturer recommended ball size distribution 64 5.3 Results and discussion 65 5.3.1 Ball size distribution effect 65
Foremost among these is ore competence, though feed size comes a close second. This sensitivity is due to the reliance of ag/sag mills on the feed ore for their grinding media competence and size. Ag mills are the most sensitive in this respect with sag mills being increasingly less so as the ball charge is increased.
An optimization is carried out to minimize the yearly cost of energy for the operation of the SAG mill. This cost includes the energy consumption cost in $/kWh and the capital cost for the PV-BESS infrastructure, prorated over the life of the battery system, accounting for the discount rate through an annuity factor (Pamparana et al. 2019a, b).The energy requirements are …
Nowadays, experimental semi-autogenous (SAG) mill and drop weight test are used for evaluation of grinding circuit regarding changes in feed particle size …
The breakage rate distributions are affected by a number of operating conditions. Morrell and Morrison (1996) modelled the effect of ball charge, mill filling, feed size distribution and mill speed on each breakage rate. The resulting 5 empirical equations are embedded in the current JKSimMet Variable Rates AG/SAG model.
Figure 3 shows the relationship of throughput vs. SAG power (PWR) for a liner life in a mill. The figure shows that the range of SAG power from 14.5MW to 17.0MW is associated with higher throughput, and that higher power is associated with lower throughput, which may be caused by hard ore and/or coarse feed.
Secondary mill feed – Continuous regulation capability gate to allow controlled distribution of feed between the two ball mills. Finally, if the amount of …
Medium Grind – 80% passing size between 106 and 75 µm. To mill in single stage SAG configuration, the feed must be consistent, not too coarse or too fine. The downstream process must be able to handle fluctuations in the grind size. If these two factors cannot be satisfied the choice of an SAB or SABC circuit is favoured. 3.
ore particles. In a SAG mill, external grinding balls are added in the chamber to aid in the grinding process. Napier-Munn (Napier-Munn et al., 1996) classified the breakage mechanisms occurring within AG/SAG mills into three categories: high energy related impact breakage, low energy related abrasion, and attrition.
The outcome of the crushing circuit improvements was a finer feed size to the SAG mill on Wallaby Deeps underground ore. SAG mill feed size distributions from samples collected in late 2011 (before screen changes) and early 2012 (after changes) are shown in Figure 3.
Influence of feed size on AG / SAG mill performance. The experimental assessment of ball mills type MCB 4.5x6 (МШЦ 4,5х6) operating in copper ore processing plant and SAG mill 8.5x5.3 operating in gold ore processing plant are presented. The….
The feed rate setpoint can then be tied into a SAG mill power optimisation strategy. SAG Mill Discharge. Controlling the feed and discharge of a mill is mostly a stabilisation exercise – you need to be able to quickly and accurately control the mill feed rate. If the mill feed setpoint is changed, then the actual feed rate needs to stabilise ...
Due to this the SAG mill feed size distribution differs significantly to that of the circuit fresh feed (RoM ore) as shown in Figure 1. It is important to account for the circulating load in ...
different size distributions, because different size distributions can have the same F80. The feed size distribution is also the implicit result of the ore competence (affecting blasting and crushing performance). This distribution affects the SAG mill load and the load affects directly the mill power and the efﬁciency of the mill operation (Van
Factors such as mill speed, mill inlet water, feed size distribution, and ore hardness all have an inﬂuence on the grindcurve, and form an integral part of the optimisation process. Test work has been conducted at a number of sites to develop grindcurves for different mills treating a range of ores.
antimonygold ore flotation plant... 2013Seven Mexican properties supply direct-shipping ore, or mill feed, ... effect of sag mill feed size distribution and ... equipment specification sheet sag mill.
Optimization of mill performance by using online ball and pulp measurements Soon after a stop, a mill is a dangerous place to enter for the personnel tasked with taking measurements or samples. Crash stops are difficult to handle. The mill and all feed streams should be stopped simultaneously but, often, they are stopped around about the same time.
Ball mill: When the particle size of the product is less than 0.5mm, the grinding effect of the ball mill is greater than that of a rod mill of the same specification. SAG mill: The SAG mill has a wide range of feeding particle sizes and can process larger minerals, but at the same time, its output particle size is relatively larger.
Highland Valley Copper recently implemented a system of measuring run-of-mine (ROM) ore properties and monitoring their effect on both mine and mill performance. These properties are principally ore hardness and size. For some years, Highland Valley Copper has been estimating ore hardness using knowledge of the geological conditions combined with previous mill …
Ø Manipulation of SAG Mill Operating Parameters (eg. load, ball charge, speed and density) Ø Maximising Pebble Recycle Load and Crusher Interaction With the SAG Mill I-12 Ø Effect of SAG Mill Feed Size Distribution and Ore Variability Ø Mill liner design modifications, and Ø Circuit Design Considerations That Influenced Throughput
The effect of feed size in AG/SAG milling has been studied extensively with an early review presented by Abel (1997), whilst the relationship between changes in feed size and comminution has been covered by a number of authors under the banner of "Mine to Mill" (Morrell and Kojovic, 1999).
Control of -SemiAutogenous Grinding(SAG) mill weight is an example of an important process that exhibits many of these aspects. Maintaining the SAG mill weight at the optimum value is critical for achieving maximum grind rate efficiency and mill production (Powell, M.S., van der Westhuizen, A.P., & Mainza, A.N. 2009).
identify where the opportunities were greatest and what effect the combined changes would have on mill performance. Initially, the focus was to reduce the SAG mill feed size while processing the lower tonnage Subika ore and improve the grinding circuit product size while processing the ball mill limiting Apensu ore.
(SG) of 2.76. The battery limits for the energy study were established as being the feed to the SAG circuit (coarse ore stockpil e) and cyclone overflow of the ball mill grinding circuit (feed to flotation circuit). The particle size distribution of the coarse ore and cyclone overflow samples are shown in Figure 5. 124
Blasted ore is further reduced in size by primary crushers, semiautogenous (SAG) and autogenous (AG) mills. SAG mills have special requirements on feed size distribution, which is influenced by the size distribution of the blasted rock (Esen 2013).The 80% passing size, x 80, is regularly used to evaluate the energy draw in size reduction (Workman and Eloranta 2003).
THE INFLUENCE OF MILL SPEED AND PULP DENSITY ON THE GRINDING EFFICIENCY 91 Graph 2. Particle size distribution for different mill speeds 68.8 % solids 73.4% solids 75.9% solids Ore solids density 3.1 3.1 3.1 Dry feed rate (kg/h) 289 288 287 Speed (rpm) 35.31 35.11 35.00 % Vcrit 75.59 75.17 74.92 Absorbed power (kW) 5.335 5.628 5.338
"The control of the operation of semi autogeneous grinding (SAG) mills is mainly achieved through adjustments of feed rate, water addition and speed of rotation. With the introduction of image based sensors it is possible to have on-line measurements of the size distribution of the ore feeding a SAG mill.