Ball Size as Initial Charge. Commercial ball sizes 10 – 150 mm; Number, size and mass of each ball size depends on mill load and whether or not the media is being added as the initial charge. For the initial chargin of a mill, Coghill and DeVaney (1937) defined the ball size as a function of the top size of the feed, i.e., dâ†"V = 0.40 ...
The mill charge PSA is compared to that of the feed to identify any coarse build-up. The size-by-size density of the rocks constituting the mill charge is also measured, as it can be significantly different from the feed, which could affect the power draw predictions, especially in fully autogenous or low ball charge applications. The mill charge
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.
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.
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.
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= ...
CHARGE LEVEL. Maintaining an optimum charge in a SAG mill remains one of the fundamentals for efficient mill processing. If the charge level or the ball to charge ratio is incorrect, breaking liners and/or increasing power consumption is inevitable and can only result in degraded mill efficiency.
Oct 10, 2016· Understanding Size Effects of Semi-autogenous Grinding (SAG) Mill Operation as a Pathway to Solving Feed Disturbances - Case Study using the MMG Century SAG Mill, in Proceedings 13th AusIMM Mill Operators' Conference 2016, pp 321–330 (The Australasian Institute of Mining and Metallurgy: Melbourne)."
APPLICATION ENVIRONMENT For SAG milling applications, the diameter of the balls, mill and throw action of the charge provide for a high impact environment - therefore a balance must be achieved between abrasion resistance and impact resistance in SAG balls to avoid excessive breakage.
Jan 11, 2018· Attrition mill is a type of grinding mill by kinds of media to crush lump to powder-like substances. The impact can be rock on rock such as in an Autogenous Grinding (AG) mill, rock and a small ball charge (~10%), used in Semi Autogenous Grinding (SAG) mills, balls of various sizes in Ball Mills and less commonly these days, steel rods in Rod Mills.
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.
May 24, 1990· Abstract: 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 ...
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 …
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.
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 ...
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 …
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 …
Although it is well known and easily experienced that the feed size distribution influences the throughput and stability of operation of a semi-autogenous grinding (SAG) mill, the details are poorly understood since it is often only the input and output measurements that are used to identify unfavourable in-mill conditions. Load cells and power monitoring are sometimes used but are generally ...
- 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
• 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 charge's toe and shoulder angles.
The traditional operation of SAG mills relies on the operator to adjust the manipulated variables to maintain the target mill load and power draw. Changes to the ore hardness, feed size or ore specific gravity require an alert operator to adjust the variables while …
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.
Jul 01, 2019· 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 defined by the SAG ...
SAG mill. SAG is an acronym for semi-autogenous grinding. SAG mills are autogenous mills that also use grinding balls like a ball mill. A SAG mill is usually a primary or first stage grinder. SAG mills use a ball charge of 8 to 21%. The largest SAG mill is 42' (12.8m) …
make-up ball diameter of about 1.7 inches, that is, a mixture weighted. toward 1.5 inches. (3) An increase of 12% in capacity was predicted with the optimum make-. up ball charge with respect to a ...
Feb 18, 2020· 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
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
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,