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.
Jun 06, 2016 While critical-size could be of any dimension, it is most typically synonymous with pebble-crusher feed, with a size range of 1375 mm. Critical-sized particles can result from a simple failure of a mills breakage rates to exceed the breakage rate of incoming particles, and particles generated when breaking larger particles.
Sep 08, 2013 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.
May 24, 1990 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
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.
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
The bulk density of a new rod charge is about 6.25 t/m 3. With time due to wear the bulk density drops. The larger the mill diameter the greater is the lowering of the bulk density. For example, the bulk density of worn rods after a specific time of grinding
When the feed size of a SAG mill becomes coarser, i.e. r increases, the energy required to break the ore increases, i.e. r and f increases (Morrell et al., 1996 Morrell and Valery, 2001 ...
Nov 26, 2019 The biggest characteristic of the sag mill is that the crushing ratio is large. The particle size of the materials to be ground is 300 400mm, sometimes even larger, and the minimum particle size of the materials to be discharged can reach 0.1 mm. The calculation shows that the crushing ratio can reach 3000 4000, while the ball mills ...
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.
Mar 21, 2007 The optimal performance of AG/SAG mills is the key to successful plant operation. All AG/SAG mills using radial or curved pulp lifters suffer from inherent material transport problems such as slurry and pebble pooling, which decrease throughput and increase energy consumption.
OPTIMAL SAG MILL CONTROL USING VIBRATION DIGITAL SIGNAL PROCESSING TECHNIQUES ABSTRACT Recent developments in low power wireless and Digital Signal Processing (DSP) technologies have given rise to a new system that can monitor vibrations in real-time on the rotating surface of SAG, AG, and Ball mills.
SAG Mill Feed rate, tlh 950 lBall charge, % 8-1 0 lverae power, kW Iotal charge, % 1 24 1 8600-9600 1 ... Full mass flow and size balance around the SAG and ball mill circuits ii) Power response of the SAG and ball mills ... practicable and the ball and total charge at optimum levels 1070tlh was achieved. A full survey under these conditions was
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 ...
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,
EF5BM P8010.3 1.145P80 ( 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 m) from Table 1 and the P80 is the ball mill circuit product. The EF5 factor only applies below 75 m to ball
Ball Mill Grinding Media Options. Apr 26, 2019 A ball mill is a form of grinder that is used to blend or grind materials for use. It is a cylindrical device mainly for grinding material such as iron ores, ceramic raw materials, glass, steel, etc. The ball mill works on impact and attrition principle.
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. (4% ball charge, 90% Nc) A cross between AG and SAG for competent, abrasive ores. As typically operated in RSA. 6 SAG mill (configurations 3, and 5 ) with recycle crusher
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 ...
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 at the new target in a short period of time. The feed rate setpoint can then be tied ...
The ball mill oversize feed factor (EF 4 BM) is always calculated with the rod mill work index for the optimum feed size and the ball mill work index for EF 4 BM. The model assumes that the calculated value of E ssbm the specified contingency is greater than the sum of E sag E peb otherwise E bm will be negative.
3.5.2.2 Ball Mills. The ball mill accepts the SAG or AG mill product. Ball mills give a controlled final grind and produce flotation feed of a uniform size. Ball mills tumble iron or steel balls with the ore. The balls are initially 510 cm diameter but
variability in rock size and rock competency. This applies to both fully autogenous and semi-autogenous (SAG) grinding circuits. In this paper we focus on an approach to overcome the problem of inconsistent mill through-put related to variability in mill feed size and rock competency. The focus is on ores containing hard, competent rock.
the size and number of particles in the SAG mill was mainly investigated based on discrete element method. For optimal speed control, an improved sliding mode control of
Jun 17, 2021 Due to its strong lifting capacity and excellent grinding performance, the trapezoidal liner is widely used in the SAG mill. The structure of the trapezoidal liner is shown in Fig. 1, the main dimensions are dip angle (tau), length of the top edge (L) and height (h).Dip angle (tau) determines the trajectory of the mediums in the SAG mill, which directly affects
Dec 01, 2005 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
In this study, the relationship between the optimal speed and the size and number of particles in the SAG mill was mainly investigated based on discrete element method. For optimal speed control, an improved sliding mode control of the exponential approaching law is proposed to improve the stability and rapidity of sliding mode control near the ...
Jan 01, 2016 The SAG mill had a 68% 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.
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
Oct 12, 2017 SAG mill make use of steel balls included with some large and hard rocks for grinding. These mills utilize the balls in making the large fragments of materials broken into pieces. The ball charge of a SAG mill is about 9% to 20%.This process takes place inside the large rotating drum of SAG mill which is filled with balls partially.
Mill charge % 41.46 41.35 . Mill ... ball charge level and ball size were studied in the SAG mill circuit as well as an optimum circuit configuration for the ball mill circuit and classifiers ...
LG A mill power equation for SAG mills. Minerals and Metallurgical Processing. Feb 1990 pp57-62. Gross power No load power Net power drawn by the charge (8.13) The net power is calculated from Net power KD2.5L e c./ Watts (8.14) In equation 8.14, D is the diameter inside the mill liners and Le is the effective length of the mill including the ...
Sep 01, 2013 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 451 using a 1 m diameter mill. It can be seen that the optimum portion of the 50.8 ...
Particle size distribution with user-definable statistical measures Cumulative volume flow estimation. Learn more about RockSense MillSense system. The MillSense system provides on-line analysis of the mill charge position and volume by directly measuring the charges toe and shoulder angles.
- Ball Charge Regimes 19 - Test Requirements 20 ... - Pebble Mills 21 - 2 - 2 CHAPTER 7 FULLY AND SEMI AUTOGENOUS (AG AND SAG) MILLS 22 - High Aspect vs. Low Aspect Mills 22 - Mill Sizing Consideration 23 - Breakage Rate/Population Balance Model 23 - Power Model 23 ... SELECTION OF OPTIMUM SIZE GRINDING MEDIA 39 - Rods 39 - Balls 40