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SAG/ball (SAB) configurations represent the dominant comminution flow sheet within the company and the circuit configurations employed include SAB, SABC-A, SABC-B and single-stage (SS) SAG milling, with SAG mill feed ranging from run-of-mine (ROM) ore through to secondary crusher product.
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Using a power modelling approach, different mill sizes are selected to meet the power requirements that achieve the design tonnage. In the figure below, the range of expected throughput for different ore types are plotted for a fixed grinding circuit; each ore type can process between 80% and 120% of the design throughput.
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In multi-stage ABC/SABC circuits, the AG or SAG mills are in closed circuit with screens and pebble crushers. The mill discharge from these mills consists of slurry, which goes to the ball mills for further grinding, and coarse pebbles/rocks, which are crushed and sent back to …
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circuit is shown in Figure1. It is commonly referred to as a SABC circuit, for Semi-Autogenous Ball mill Crusher (SABC). This circuit shows a semi-autogenous grinding (SAG)/ball mill circuit where both grinding mills are in closed circuit, with the SAG mill closed with a crusher to control the amount of 'critical size' material in the circuit.
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Generally, the discharge from AG/SAG mills consists of one or both of the following components: slurry (water and finer particles) and pebbles (20-100 mm). Single stage AG/SAG mills have to handle large amounts of slurry as they are generally in closed circuit with classifiers whose circulating loads reach as high as 400-500%.
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The SAG Power Index (SPI) test (Starkey & Dobby, 1996) uses a benchscale SAG mill test to - determine the specific energy of an industrial SAG mill. The test is operated in closed circuit and the time required to grind the material to a P 80 of 1.7 mm is used to predict AG/SAG specific energy using Equation
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Amelunxen SGI Model. This is a model that estimates the specific energy consumption of a SAG or AG mill plus ball mill circuit using the equation by Amelunxen (2014) for E SAG and the classical Bond work index equation for E ball substituting CF ball in the place of the Rowland efficiency factors.. The model requires manual calibration factors for both equations (CF SAG …
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The range of mill sizes and versatile applications allow SAG milling to be accomplished with fewer lines than conventional set-ups. This, in turn, contributes to lower capital and maintenance costs for a SAG mill circuit. Versatile applications . SAG milling extends itself to many applications due to the range of mill sizes available.
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Simulation work was carried out to analyze how feeding a finer size distribution to a single stage SAG mill in closed circuit with hydro cyclones at Freda Rebecca Gold Mine would affect through put and specific energy consumption using an Excel based milling process simulator developed by Hinde, a comminution specialist who has worked for Mintek for many years. Other …
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by the installation of a 12MW SAG mill with a diameter of 10.97m (36ft). The mill, when built, was the largest SAG mill operating at any existing Australian mine. To aid in commissioning and optimising the mill, the Julius Krutt- schnitt Mineral Research Centre (JKMRC) and plant staff con- ducted extensive surveys of the grinding circuit.
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Case Study #1 – Improving Circuit Stability OMC have been assisting an African gold mine in optimising the comminution circuit, with a focus on operations practices and plant utilisation. The original circuit configuration consisted of a primary crusher followed by a SAG mill with a pebble crusher and a ball mill (SABC).
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For closed circuit single stage AG/SAG applications, the design and operation of closing hydrocyclones is critical in the overall performance of grinding circuit and …
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The circuit comprises a SAG mill, 12 m diameter by 6.1 m length (belly inside liners, the effective grinding volume), two pebble crushers, and two ball mills in parallel closed with cyclones. The SAG mill is fitted with a 20 MW gearless drive motor with bi-directional rotational capacity. (Reversing direction evens out wear on liners with ...
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The Bond efficiency factors of 48-61 % were obtained for the BGM grinding circuit, indicating an inefficient operation. This suggests that the operation could achieve targets by lowering the throughput. Further, the SAG mill circuit was characterized by fluctuating feed size of between x. F, 80 =102 to 185 mm. A need for control of the feed
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SAG circuits may employ low to relatively high ball charges (ranging from 2% to 22%, expressed as volumetric mill filling) to augment autogenous …
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Where the SAG mill/ball mill circuit is the bottleneck in the processing plant the pebble circuit can be a significant factor in limiting overall plant capacity. The pebble circuit recirculating load can be very significant (depending on the ore characteristics and SAG mill operating dynamics).
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The SAG mill circuit also includes a single-deck screen and a cone crusher while the ball mill circuit utilizes hydrocyclones. Currently, the grinding circuits are inefficient in achieving the aspired product fineness of xP,80 = 125 μm even at low to normal throughputs (450-600 t/h).
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The Integrated JK Drop Weight Test provides ore specific comminution parameters that are used in the JKSimMet software to analyse and/or predict crusher and AG/SAG mill performance. This allows for optimisation of current circuits or flowsheet design for new circuits. Developed at JKTech, the Integrated JK Drop Weight & SMC Test is a single ...
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Single stage SAG Mills are very beneficial in reducing CAPEX for plants with a staged throughput approach. When future tonnage is to be increased, the SAG Mill can feed downstream ball milling to boost capacity. Amstar SAG/AG Mills range in size from 4.3m through 12.2m in diameter with powers as high as 28,000 kW.
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Optimising mill circuits for best efficiency impact. By Guest Contributor. Oct 26, 2021. Wireless LoadIQ system installed on the mill shell from which it gather mill mechanical and operational data for enhanced decision making on the mill performance and depicting the compact size of the unit. Decades of product evolution have given FL a ...
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The Ball Charge in SAG and Ball Mills, in other words, the fraction of the mill volume constituted by balls, has a significant impact on the performance of a mill and the greater Grinding circuit. Running at the wrong Ball Charge adversely impacts not only throughput but the consistency of the product particle size (P80) as well.
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The work involved participating in and overseeing the redesign of the SAG mill liner systems and developing operational strategies for maximising throughput through to the end of mine life. Ausenco's comminution optimisation tool, Ausgrind, was used to benchmark and analyse plant data with empirical models, predict circuit performance for ...
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2 AG mill + a recycle crusher Competent ore - relatively homogenous (the recycle crusher is used to balance the rate of impact breakage within the circuit) 3 SAG mill (8 – 15% ball charge) Variable competency ore 4 High ball charge SAG mill (15 to 25% ball charge) Incompetent ore 5 Low ball charge SAG mill, high mill speed.
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crushed ore is fed into a SAG/Ball mill circuit with a median size of approximately 12,000 microns. Most SAG Mills are operated in closed circuit with a screen. The screen fi lters undersized ore, normally minus ½ inch, to a ball mill discharge sump. The combined mill discharg-es are pumped to undergo classifi cation, normally via hydrocyclones.
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SAG Mill Circuit Example — Gold Processing SAG mill circuit example for gold processing [image: (135-6-3)] AG/SAG Mill. AG/SAG mills are normally used to grind run-off-mine ore or primary crusher product. Wet grinding in an AG/SAG mill is accomplished in a slurry of 50 to 80 percent solids. 2D and 3D simulations of particles in a SAG Mill
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The paper proposes a novel performance audit report for a SAG Mill Circuit. The audit report is demonstrated on a validated run-of-mine ore grinding circuit model, which the authors have captured in a simulator, using Simulink. The elements of the report combine established statistics and views with specific mill control context.
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The single-stage SAG mill circuit was shown to efficient operate ly on primary crushed, Wallaby Deeps underground material. With relatively coarse, competent feed and a reasonable ball charge, the variable speed SAG mill generated a product with sufficient fines content that the cyclones could manage without excessive recycle.
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optimization of sag mill circuit · optimized the oper ating strategies for the SAG mill circuit at Paracatu op eration in Bra zil. The focus of this project was to reach design t hroughput and final grinding product size, conditions . Mar 21, 2007· The optimal performance of AG/SAG mills is the key to successful plant operation.
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approach the total specific energy of the entire AG/SAG circuit is firstly predicted using the SAG mill feed F80 and the ball mill cyclone overflow P80. Morrell's model (Morrell, 2011) relates the feed, mill geometry and operating conditions to the specific energy of the circuit. However, the F80 is not enough to represent properly
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CIRCUIT PERFORMANCE INTRODUCTION . As the SMC Test ® produces the JK parameter values A and b as well as estimates the JK parameter ta and crusher model energy matrices, the SMC Test ® can be used to conduct AG/SAG mill and crusher circuit simulations through the use of JKSimMet. Independent
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