Optimal mill loading ensures you are making the most efficient use of your grinding mill – but in the past, it has been difficult to calculate the optimal mill load with precision. Not anymore. LoadIQ utilises our mill scanner smart sensor technology to determine the optimum mill load, increasing throughput by 3 – 6%. What we offer.
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According to available literature, the operating speeds of AG mills are much higher than conventional tumbling mills and are in the range of 80–85% of the critical speed. SAG mills of comparable size but containing say 10% ball charge (in addition to the rocks), normally, operate between 70 and 75% of the critical speed.
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decided to make SAG control one of its priorities in order to further increase throughput and improve stability. The original primary mill control logic delivered by the Optimisation Project in 2005 consisted of a simple PID loop controlling the mill charge (bearing pressure) through feed rate changes.
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Relation between Sag mill solid and product P80! Both are dependent on feed size. Dependent on Volume % solids in SAG mill. Dependent on ball charge volume. Hardness of ore. Recirculation load. Dependent on P80% size. All other parameters are secondary. In general Sag mill solids are kept at 70% by wt. Operating grinding circuit is an art.
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Mill application features. Frozen charge protection – Detects frozen charge in the mill, minimizing equipment wear and liner replacements.; Coupling supervision – Detects if a failure or slippage occurs in the couplings and stops the system in case, preventing major damages.; Stand-still detection – Prevents the motors from re-starting if the mill is still rocking or moving after a stop
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The SAG mill had a 6–8% ball charge and the power consumption was 8 kWh/t, which agreed well with the expected value. 9.6. Problems. 9.1. In an SAG mill the dimensions of the mill were 9.75 m × 3.5 m and the specific gravities of the mineral and that of the balls charged were 4.1 and 7.9, respectively.
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The mill product can either be finished size ready for processing, or an intermediate size ready for final grinding in a rod mill, ball mill or pebble mill. AG/SAG mills can accomplish the same size reduction work as two or three stages of crushing and screening, a rod mill, and some or all of the work of a ball mill. Because of the range of
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The SAG Mill has a “small” circulation load of oversize given be the 3/8″ trommel screen and the 1/2″ x 1 1/4″ discharge grates. The load of 4″ balls in this SAG is “good” but un-measured. SAG Ball consumption is “average” at 400 g/t while Ball Mill grinding media (3″ balls) usage in 550 g/t.
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The "Critical Speed" for a grinding mill is defined as the rotational speed where centrifugal forces equal gravitational forces at the mill shell''s inside surface. This is the rotational speed where balls will not fall away from the mill''s shell. Result #1: This mill would need to spin at RPM to be at 100% critical speed. Result #2: This mill''s
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torque mill test is the mill energy input divided by the solids load. The energy specific cumulative grinding rate at each screen size is calculated from a torque-mill test as in the example that follows. Torque mill solids load during test: 11.25 kg (24.8 lb) of ball mill feed sample from plant survey. Sample is reconstituted with water to be
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In semi-autogenous grinding (SAG), the grinding mill inventory, (i.e. volume of total charge, volume of ball charge, etc.) is important in determining the optimum operating condition for maximum production (tph), minimum specific energy (kwh/t) or lowest cost ($/t). A two-dimensional graphical method is presented for determining the actual ball charge within the total charge when parameters
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Depending on the mill size the SAG mills draws between 2 MW and 17 MW. 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 2.0 and 7.5 kWh per ton of energy to reduce the particle size.
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The AutoCharge system is primarily suitable for SAG mill balls (100–150 mm). As each ball rolls through the counting chute, an electro-mechanical limit switch is activated, signalling the counter. Each count is added to the last, allowing a continual increasing total count of balls to enter the mill over a set time period.
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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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mill discharge product size in relation to the lifting effect of the liners. In this specific case, it is obvious that a certain load expansion is needed to allow the coarse particles entering the media charge to be reduced. Therefore, at this stage, a direct measurement of the dynamics in the mill gives very valuable information to the operator.
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The original SAG mill control loop, a mill motor power draw set point of 5200 Amperes controlling the coarse ore feeder speeds, was soon found to give excessive variation in the mill ore charge volume and somewhat less than optimal power draw.
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With high aspect ratio SAG mills total charge to ball charge ratio should be greater than 2 (up to 2.5) for a coarse mill feed (say F80 > 110 mm). If the mill feed size is fine, say 50 mm or 30 mm, then you are looking at a total charge to ball charge ratio of about 1.5-1.6.
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is derived from the power required to maintain mill revolutions with the mass of charge acting at the centroid of the mass. This is a form of equation used by many Optimum Feed Size for ball mills F Wb =4 000 13,* MILLCALCv2a 7 19/02/2004. size and power relationships For SAG mills the equation becomes Power=
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For SAG milling applications, the diameter of the balls, mill and throw action of the charge provide for a high impact environment
The minimum ball size in the charge was taken as 12.7 11 shows the results of the grinding of a feed of various sizes at a size reduction ratio of 45:1 using a 1 m diameter mill. It can be seen that the optimum portion of the 50.8
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Optimisation of the Cadia Hill SAG mill circuit PDF Download . Oct 21 2015 SAG Mill I12 Ø Effect of SAG Mill Feed Size Distribution and Ore Variability Ø Mill liner design modifiions and Ø Circuit Design Considerations The effect was consistent with 70mm 90mm and 80mm grate apertures no matter what the theoretical 39open area shell liner life mill load operating Oct 21 2015 SAG Mill I12 Ø
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The mill product can either be finished size ready for processing, or an intermediate size ready for final grinding in a rod mill, ball mill or pebble mill. AG/SAG mills can accomplish the same size reduction work as two or three stages of crushing and screening, a rod mill, and some or all of the work of a ball mill. Because of the range of
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The analysis of the influence of ball sizes in SAG grinding hasn''t been developed in detail by considering the effect on process parameters inside the mill, grinding efficiency or internal classification. Historically a conventional grinding reference has been made on the empirical procedure developed by Azzaroni (1980).
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EF5BM=[ P80+10.3 1.145×P80] ( 3 ) The EF4 formula requires both the rod mill and ball mill work index (rod mill Wi is used to calculate the optimal feed size) and because this is a “single-stage ball mill” calculation, the F80 is actually the rod mill feed size (10,000 µm) from Table 1 and the P80 is the ball mill circuit product. The EF5 factor only applies below 75 µm to ball
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the conditions of the liners, grinding ball percentage, and overall charge level inside the SAG mill without the need to pull the feed chute, presents a huge opportunity for improving mill availability, comminution mill is nonoperational. The least optimum method of monitoring liner wear involves waiting until the liner bolt heads wear
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The mill product can either be finished size ready for processing, or an intermediate size ready for final grinding in a rod mill, ball mill or pebble mill. AG/SAG mills can accomplish the same size reduction work as two or three stages of crushing and screening, a rod mill, and some or all of the work of a ball mill. Because of the range of
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and optimal grinding charge trajectory for the SAG, Ball and Rod Mills. • Identified potential benefits could be obtained with an ideal grinding media charge, mill speed as well as optimisation of lifter profile (specialty lifter face 20 angle) which is directly related with mill power draw, internal motion of mill charge,
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operation of SAG mills. SAG mills are currently the technology of choice in hard rock milling operations for reducing primary-crushed ore to ball mill feed. In recent years, the trend has been towards larger-sized SAG mills with diameters of 10.4 m (34 ft) and above, with the largest being 12.2 m (40 ft) in
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respect with SAG mills being increasingly less sensitive as the ball charge is increased (Morrel S and Valery W, 2001). 2.2. EFFECT OF FEED SIZE DISTRIBUTION ON SAG MILLING The qualitative effect of changes in particle size distributions (PSD) on the SAG mill performance can be addressed by using the grind curves.
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The original SAG mill control loop, a mill motor power draw set point of 5200 Amperes controlling the coarse ore feeder speeds, was soon found to give excessive variation in the mill ore charge volume and somewhat less than optimal power draw.
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The minimum ball size in the charge was taken as 12.7 11 shows the results of the grinding of a feed of various sizes at a size reduction ratio of 45:1 using a 1 m diameter mill. It can be seen that the optimum portion of the 50.8
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