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If you have to reduce the SAG mill speed because of avoiding liner breakage, maybe it's better to modify the shell lifter design. Low speed may cause decreasing capacity, higher steel ball and liner wear rate. D80 of SAG mill may be finer because of more cascading action and less capacity which results in more retention time in SAG mill.
Raw Bond Model. This is a SAG or AG mill plus ball mill model that estimates the specific energy consumption (E SAG) using the 1979 Barratt equation and the classical Bond work index equation including Rowland efficiency factors.The model allows a manual calibration factor on both equations (CF SAG and CF ball, respectively).This formula usually gives higher total circuit specific energy ...
The ball-mills in SABC circuits are operated at a relatively high speed (70–78% of critical speed), with large balls (50 mm to 80 mm), to cope with a coarse feed (a transfer size from the SAG mill typically larger than 10 mm) and to maximize power draw.
An increase of over 10% in mill throughput was achieved by removing the ball scats from a single -stage SAG mill. These scats are non- spherical ball fragments resulting from uneven wear of balls ...
Nowadays, experimental semi-autogenous (SAG) mill and drop weight test are used for evaluation of grinding circuit regarding changes in feed particle size distribution, size of the ball, speed of ...
Pictures of the insides of an AG mill and a SAG mill which have been crash stopped are shown in Figures 5 and 6 respectively. Accurate measurements of the ball filling can only be made after the mill is ground out. In this case the mill is operated with the feed turned off until all of the ore has exited the mill.
8 - 9 August 2011 Perth, WA. Fig. 1- Increase in throughput over liner life for a large SAG mill. Unfortunately however, the 32 ft SAG mill that was studi ed for this project does not feature ...
The development of the inferential measurement models of SAG mill discharge and feed streams and mill rock and ball charge levels, detailed earlier in the series, is summarised here.
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. Fuller-Traylor SAG/AG Mills range in size from 4.3m through 12.2m in diameter with powers as high as 28,000 kW.
A detailed test work was carried out with an industrial semi-autogenous (SAG) mill in a copper plant in close and open circuits to specify the effects of ore characteristics and operational ...
Of course all the ball mills operate in slurry pooling conditions but with low ball charge it will be larger than before so it will affect the P80 (Ball mill Product 80 % passing not circuit product) badly and it will increase. ... Difference Between Sag Mill vs Ball Mill - mech4study ... of the volume of the shell of the ball mill and the feed ...
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.
For this purpose, the strength properties of the SAG mill feed and product were specified by different techniques, including the point load index, impact breakage parameters (A × b), abrasion index (t a), and Bond ball mill work index (W i).
Ball mill: When the particle size of the product is less than 0.5mm, the grinding effect of the ball mill is greater than that of a rod mill of the same specification. SAG mill: The SAG mill has a wide range of feeding particle sizes and can process larger minerals, but at the same time, its output particle size is relatively larger.
ness of the models. For a given mill to have a combination of feed size, ball load, mill speed and % solids will represent the total load. Ball Mill SAG Mill Scw Jb Pc % -6" +1" N/Nc Fresh Feed Water Water Pebble Crusher Screen Cyclones Sump Pump Fig. 1. SABC A/B milling circuit.
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. …
Mill Type Overview. Three types of mill design are common. The Overflow Discharge mill is best suited for fine grinding to 75 – 106 microns.; The Diaphram or Grate Discharge mill keeps coarse particles within the mill for additional grinding and typically used for grinds to 150 – 250 microns.; The Center-Periphery Discharge mill has feed reporting from both ends and the product discharges ...
The ball mill has higher circulation load, it generates only 30 -35% of actual fines you require to be called as product. If your product size needed is passing 45 micron, then the ball mill total discharge material will contain normally 30% of 45 micron. The rest is oversize which has to be ground again.
This is a SAG or AG mill model that estimates the specific energy consumption (E SAG) using the equations of Morrell (2004). Testwork Required. The SMC™ test, stored in the "DWT" testwork table (SMC is a Drop Weight Test). Bond ball mill work index. The method requires all the parameters of the ball mill work index test to be filled in: Ball ...
Sag mill grinding circuit design911metallurgist 2016 6 6 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 mill s breakage rates to exceed the breakage rate of incoming particles and particles.
If a ball mill contained only coarse particles, then of the mill grinding volume and power draw would be applied to the grinding of coarse particles. In reality, the mill always contains fines: these fines are present in the ball mill feed and are produced as the particles pass through the mill.
THE INFLUENCE OF MILL SPEED AND PULP DENSITY ON THE GRINDING EFFICIENCY 89 Pilot plant description The milling pilot plant consists of two containers mounted on top of each other (see Figures 1 and 2). The bottom container holds the mill, the drive train, rollers and the high-tension cabinet. The feed boxes (fine and coarse feed) are built into the
The operating principle of the ball mill consists of following steps. In a continuously operating ball mill, feed material fed through the central hole one of the caps into the drum and moves therealong, being exposed by grinding media. The material grinding occurs during impact falling grinding balls and abrasion the particles between the balls. Then, discharge of ground material performed ...
After closed-circuit secondary crushing, the SAG mill feed 80% passing (F80) size was 25 mm to 30 mm. Installed grinding power is split equally between the two mills with the SAG mill fitted with a variable speed drive (VSD). SAG discharge screen oversize ('pebbles' or 'scats') was … Readmore
SAG lifter and end cone geometry - can change SAG mill performance more than 20%-50% depending on P80 transfer size and Axb, some of which is published and some will be published at SAG 2015. SAG mill wear rates and performance changes with wear morphology, grate details, mill speed changes and optimization with speed control Ball feed size SAG ...
Feed size-F80-3 mm Product size-P80-1000micron Ball Size 3 inch or ... The Effect of the Mill Power on the Throughput 19 1320 1340 1360 1380 1400 1420 1440 Throughput, mt/h Lifter Face Angle (°) Mill Power ... and optimal grinding charge trajectory for the SAG, Ball and Rod Mills.
This paper presents a dynamic simulator of the electromechanical coupling start-up of a ball mill. The electromechanical coupling model based on the dynamic model of the ball mill, the characteristic equation of the clutch, and the dynamic model of the induction motor is established. Comparison between the simulation results of angular speed, load torque and current obtained from the model ...
Obviously, the SAG mill is consuming more and the ball mill less power than was predicted by the empirical method, but the overall total is 99.5% of the predicted total. Examples The Hemlo gold project of Teck-Corona (1000 mtpd) provides an example of mill sizing using the empirical calculation method alone.
Ball mills tumble iron or steel balls with the ore. The balls are initially 5–10 cm diameter but gradually wear away as grinding of the ore proceeds. The feed to ball mills (dry basis) is typically 75 vol.-% ore and 25% steel. The ball mill is operated in closed circuit with a particle-size measurement device and size-control cyclones. More
In addition to high impact SAG mill grinding, media is used in other types of milling such as the finer grind of ball mills, tower mills, vibration mills and regrind mills. Many variables influence the size reduction performance in a mill, including the media size, shape & quality, the properties of the incoming ore feed, the ratio of feed to ...
AG/SAG mill feed, trommel screen undersize product (-5.00 +0.00 mm), ball mill discharge and cyclone feed, overflow and underflow have been conducted in order to characterize the particle size distribution in the products and to carry out mass balancing of grinding circuits. Furthermore, an
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 mill sizes available, AG/SAG milling can often be accomplished with fewer lines than in a conventional rod mill/ball mill circuit. A diagram of types of AG/SAG ...
By combining with SAG discharge and screening on the SAG discharge screens, top size control to the ball-mill circuit feed is maintained while still unloading …
Optimization of mill performance by using online ball and pulp measurements Soon after a stop, a mill is a dangerous place to enter for the personnel tasked with taking measurements or samples. Crash stops are difficult to handle. The mill and all feed streams should be stopped simultaneously but, often, they are stopped around about the same time.
The SAG Mill is a machine added by Ender IO.It uses Micro Infinity (µI) to grind (or mill) items into their crushed variants, like Ores into Dusts.The SAG Mill has four output slots; recipes can have 1-4 different outputs, with different chances of obtaining those outputs. Uniquely, the SAG Mill can use Grinding Balls made from various materials to increase energy efficiency (resulting in ...
Feed size effects what size is important? historically, Mine-to-Mill has – focussed on blasting alone – generation of more fines • pass through SAG mill onto ball mill circuits • higher throughput (e.g. 10% to 30%) • coarser grind size (possibly) fine <25mm medium 25 - 75mm coarse >75mm
Power based modelling of single stage AG and SAG mill . other methods The ball mill correction factor CFnet is empirical and one way of estimating it was presented by Amelunxen at the Procemin 2013 Short Course by Doll Amelunxen The SGI equation uses a transfer size between a SAG and ball mill it is proposed that a synthetic transfer size of 2100 µm be used to model single stage …
Accordingly, the mill power consumption decreased from 8.4 to 5.16 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 ...
Based on these test results, a 6.7 m diameter × 2.1 m length SAG mill and a 3.3 m × 6.1 m ball mill were installed for commercial operation in closed circuit with a hydrocyclone. 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