A generalized SAG mill power draw equation developed by Austin, is given by: where the parameters used in the model are defined as: mp= net mill power (kW) K = a constant (kW/ton ) D = mill internal diameter (m) L = mill length (m) J = fractional volume of mill filled by total charge. εB = effective porosity of the total charge.
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Inferential measurements of SAG mill discharge and feed streams and mill rock and ball charge levels, detailed earlier in the series, are utilised in a simulation environment. A multivariable ...
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SAG mills are the main workhorses in the majority of comminution circuits globally. They need to be fed and kept working round the clock. ... analyse incoming information from LoadIQ as well as ore properties and internal mill dynamics together with board power usage, mill weight and bearing pressure. It can then automatically take corrective ...
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Mill power Mill sump level Hydro cyclone pressure Ore feed a a a a Water feed a a a a Mill speed a Mill size a Model predictive control on a SAG mill and ball mills The solution for the SAG Mill is an adaptive controller which controls mill load using direct mill weight measurement or indirectly from bearing oil pressure. The solution ...
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the fill level ratio, and the steel ball ratio on the SAG mill. Finally, through statistics and analysis of particle information and mill power under di erent conditions, we analyzed the influence of three parameters on the particle fracture e ect in the SAG mill and obtained the best operating parameters of the SAG mill. 2.
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Abstract and Figures. Semiautogenous (SAG) mill total load and ball load have a marked influence on mill performance. Direct measurement of these inventories is difficult, hence inferential ...
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Accordingly, the mill power consumption decreased from to kWh/t (a nearly 40% reduction), and the fresh feed flow rate increased from 515 to 615 t/h (a nearly 20% increase in the mill ...
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The SAG mill power draw model of Austin (using the calibration by Doll, 2013) is used to predict the process power draw at the mill shell, P shell, and the efficiency losses for the drive's ...
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The average consumed energy at SAG and ball mills to produce one ton of final product was kWh/t and kWh/t respectively. Thus, the ball mill consumes kWh/t, more energy than the ...
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was surprising that the Bond Rod Mill Wi average was kWh/t. Since the ore is unusually soft, the Rod Mill Wi is probably irrelevant in determining required power for the SAG mill. Drop Weight Tests Drop Weight tests were done at Hazen and analyzed by Contract Support Services, Inc. Table 4: Summary of 6 JKTech Drop Weight Tests
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Instead relatively cheap and accurate powerbased techniques are used following the development of equations which accurately predict the specific energy and power draw of AG/SAG and ball mills ...
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The variation of feed particle size significantly affects the overall process control, product quality, and economic performance of the mill [2] [3] [4]. Poor product quality from the AG/SAG mill ...
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AG/SAG Mill Power. In designing crushinggrinding flow sheets, correct estimations of mill power draw are important as it serves as one of the deciding factors for selecting an option between AG/SAG mills. ... The drop weight test has been described in Chapter 3. The tumbling test is as follows. Test conditions: 1. mill size: 305 × 305 mm ...
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Tracking the mill performance showed that the mill power consumption decreased from to kWh/t (a nearly 30% reduction), P80 of the mill product decreased from 611 to 355μm, and the mill ...
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Highlights Abstract Keywords SAG milling Power modelling Especific energy modelling SAG mills operation data 1. Introduction Comminution, especially milling, is the most important operation in mineral processing, both for its relevance to the downstream processes as well as for the high costs associated with the energy consumption.
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This variation comes generally at a sace in motor efficiency because the reduced power demand from the mill is lost in the speed control circuit. As mentioned above if the power is approximately 6000 horsepower or less a single pinion can be used, allowing the use of a synchronous motor and air clutch for low inrush applications.
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The product from the SAG mill is further reduced in size using pebble crushers and ball mills. Hence, typical gold or copper ore requires between and kWh per ton of energy to reduce the particle size. Considering a typical mining operation processes 10,000 to 100,000 tons per day the energy expenditure in grinding is 50 percent of the ...
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Published in MATERIA 2021;23:6366 The idea of minetomill optimization has been tested in various mines in last decades, resulting in higher mill throughput in many mines, but also ...
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m length (190) single SAG mill equipped with a 20 MW electric motor. The SAG mill product flows to two m (120) by m (240) horizontal screens, whose combined oversize (pebbles) is diverted to two MP 800 cone crushers. The crushed product returns to the SAG mill feed, closing the primary grinding circuit. The horizontal screen ...
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• SAG Mill Design Test (Starkey, 2006). There are reasonable correlations between all the tests' data that generally allow any or all of the data to be used to design a SAG mill based grinding circuit for 'typical' ores of a moderate competence range. Issues have arisen where the expected SAG mill specific energy is greater than 10 kWh/t.
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Mill Weight Power Top Size Figure 4: Feed Top Size vs. SAG Mill Performance 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 13:00 14:00 15:00 16:00 17:00 kW Top size (mm) Top Size Power Mill Weight Figure 5: Feed Top Size vs. AG Mill Performance This is not say that ag mill performance ...
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The purpose of the primary crusher is to reduce the ROM ore to a size amenable for feeding the secondary crusher or the SAG mill grinding circuit. The ratio of reduction through a primary crusher can be up to about 8:1. Feed: ROM up to m. Product: 300mm (for transport) to 200mm (for SAG mill) Feed Rate:
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1. SAG mill is the primary tool for grinding. SAG mill is used before the other mills. Ball mill is a secondary, and it is used after the SAG mill. 2. SAG mill breaks the raw material into pieces for the further grinding. Ball mill is used to grind the pieces of raw material into. powderlike structures. 3.
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Methods to Estimate AG/SAG Mill Grinding Power Requirements. (1) Using the results of SMC data. (2) Using SAG Power Index (SPI) data. (3) Using the 1989 Barratt method updated on Alex Doll's Web site (February 16, 2015) (3) Using Don Burgess' method (11th Mill Operators Conference 2012) They seem to give very different predictions for ...
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For example for SAG mill you can use SMC,SAG mill test, JK Drop weight test or SAG power index. U. Unterstarm. 8 years ago. Unterstarm 8 years ago. Like. It depends on a number of factors but the old 1012% rule not the optimum in many cases. With less competent ores and fine feed Freeport uses up to 21% balls. Cadia around 16% for more ...
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The working principle of the selfgrinding machine is basically the same as the ball mill, the biggest difference is that the sag grinding machine uses the crushed material inside the cylinder as the grinding medium, the material constantly impacts and grinding to gradually pulverize.
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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,, van der Westhuizen,, Mainza, 2009).
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The control strategy for the SAG mill is fairly basic. Parameters which can be adjusted are feed tons per hour and mill speed. The combination of the two are used to maintain a target feed trunnion bearing pressure of 520 psi, and power draw between 95% and 105% of available current (2,620 amps).
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operation of SAG mills. SAG mills are currently the technology of choice in hard rock milling operations for reducing primarycrushed ore to ball mill feed. In recent years, the trend has been towards largersized SAG mills with diameters of m (34 ft) and above, with the largest being m (40 ft) in
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The correlation between the AG/SAG and ball mill circuit data is also very poor. Use of equation 2 shows a very different picture, the results being illustrated in Figure 7. This shows that on average the "M" operating work indices of AG/SAG and ball mill circuits are very similar and hence energy utilisation efficiencies are similar. Also
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