E&MJ asked one of Australia's experts in SAG-mill liner technology, Dr. David Royston, about recent trends in SAG milling practice and how this has affected the design of liners. "In recent years, the trend to smaller top-size ore feed into SAG mills has been matched by a trend toward smaller but more balls in the SAG mill charge.

The software uses the particular power model (Bond/Barratt, Morrell Mi, etc.) to determine what is the transfer size where the ratio of E SAG to E ball matches the ratio of mill power (1:1.5 in this example). This is the 'maximum efficiency' transfer size where the mills will both operate at …

Rod mill：The rod mill has the highest efficiency when the feed size is <30mm and the discharge size is about 3mm with uniform particle size and light overcrushing phenomenon. SAG mill: When the weight of the SAG mill is more than 75%, the output is high and the energy consumption is low with a light degree of over-crushing.

A survey of a SAG-ball mill circuit processing ore from primary crushing showed size reduction of circuit (SAG) feed F 80 of approximately 165,000 µm to flotation circuit feed (cyclone overflow) P 80 of 125 µm. The total specific energy input for the two milling stages was 14.6 kWh t −1. Calculate the operating work index for the circuit. b.

Morrell and Valery Jnr., W. (2001) Influence of Feed Size on AG/SAG Mill Performance. SAG2001 - SAG mill circuit. International Conference on Autogenous and Semiautogenous

While critical-size could be of any dimension, it is most typically synonymous with pebble-crusher feed, with a size range of 13—75 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 generated when breaking larger particles.

F80 80% passing size of the circuit feed (μm) HPGR High Pressure Grinding Roll P80 80% passing size of the circuit product (μm) PSD Particle Size Distribution ROM Run-of-Mine SAG Semi-Autogenous Grinding SMC Test® SAG Mill Comminution Test 3. KEYWORDS Autogenous Grinding (AG) mill, Ball mill, Comminution,

just about SAG mills. Our GrindingExpert™ solutions include ball mill strategies that achieve the target grind size while maximizing throughput, or when the circuit is SAG mill limited, achieve the finest grind size possible, thus increasing mineral liberation and recovery. GrindingExpert™ has been shown to typically increase throughput by ...

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.

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.

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

The basic parameters used in ball mill design (power calculations), rod mill or any tumbling mill sizing are; material to be ground, characteristics, Bond Work Index, bulk density, specific density, desired mill tonnage capacity DTPH, operating % solids or pulp density, feed size as F80 and maximum 'chunk size', product size as P80 and maximum and finally …

Other variables which can be manipulated to have an impact on mill throughput include: Mill feed and discharge water flow Use of different cyclone configurations, pressures or densities to manipulate the particle size leaving the SAG mill Varying the speed of the feeders to preferentially feed finer or coarser material from the stockpile ...

W Total = WSAG + W Ball Mill (2) Where W is the grinding mill work input in kWh/t. For the above reason, the Starkey SAG mill was built in 1991 to measure the energy required to grind ore to a size of 80% passing 10-mesh or 0.17 mm (T80) by grinding small drill core samples to precisely that size.

The capacity of the SAG mill is related to lots of factors such as feed size, size distribution, discharge size and grindability, etc., and it should be confirmed according to the actual situation. SM40*14'——means it is a dry mill.

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 - …

F = Feed size, 80% passing (µm) f(x j) = -(0.295+x j/1000000) In 2011, Morrell discussed the appropriateness of SAG mill transfer size in regards to grinding mill specific energy modelling. It was suggested that since AG/SAG mills are mostly operated in very near 274

study focussed on ball mill limited material from the Apensu open pit. Following a benchmarking study of all blasting, crushing and grinding practices in January 2009, PTI recommended changes in both blasting and crushing conditions in order to generate a finer feed size to the SAG mill.

Figure 1 shows a range of M4A SAG feed size distributions compared with an M1 feed size distribution. It is clear that the M1 material fragments very finely in the blast …

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 size as well as blending ratios was recommended for an efficient operation in terms of throughput and final product size. This could be achieved through closer monitoring of

Fo - Optimum Feed Size for rod mills F o W r =16 000 ... size and power relationships For SAG mills the equation becomes Power=(5.6115+%balls*0.1438)*D24. 6* L Mill Critical speed Crit Crit D = 42.3 n - revs per min nC= s*Crit Cs is the fraction of the critical speed

Due to this the SAG mill feed size distribution differs significantly to that of the circuit fresh feed (RoM ore) as shown in Figure 1. It is important to account for the circulating load in ...

and ag/sag mill response and provides examples of cases where feed size has been successfully manipulated. MEASUREMENT OF FEED SIZE Successful …

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 …

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 recycled through an 185 kW pebble crusher.

mill work index 11.4 kWh/t and an average RQD of 44%. RQD values of 25% resulted in a SAG mill feed size (F80) between 55 and 60 mm and throughputs of 6200 t/h. RQD values of 55% resulted in SAG mill feed size (F80) of over 70 mm and a SAG mill throughput of 5200 t/h. The Batu Hijau SAG mill specific energy was a function of point load test and ...

In these circuits the SAG mill is the largest energy consumer. In many engineering projects either a power equation and/or a specific energy equation are used for the designing of these mills but not always with acceptable results. ... but adding a variable that represents the feed size distribution. Operational data from 4 grinding circuits ...

size depending on the required mill feed rate and ore hardness. Figure 3 – Meadowbank milling flowsheet . Crushed ore is conveyed to a covered stockpile with an 8,500 t live capacity. Two variable frequency drive pron feeders reclaima the stockpiled material to a conveyer belt feeding the SAG mill in the primary grinding circuit.

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.

xG is the mill feed d80, not the circuit feed. For SAG mill, the xG value has to be determined by scalping of the full size distribution. The particles larger than the minimum pebble size (given by the pebble extraction grate opening) has to be excluded …

Comparison of SAG mill feed size & throughputs Summary of estimated UCS from Point Load Index measurements (Jan 2007) Metallurgical Hardness Testing A summary of the Bond Ball Mill Work Index (BWi ...

The oversize crusher feed size distribution, oscf, and the primary cyclone feed size distribution, pcfd, are estimated utilising the SAG mill grate size and discharge screen aperture sizes and the Rosin-Rammler size distribution function, which has been selected for its convenience and since it "has been found to fit many

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.

P80 is the SAG hydrocyclone overflow 80% passing size, µm F80 is the milling circuit feed 80% passing size, µm, fSAG is a calibration parameter for pebble crushing and/or fine feed (typically 1.0 for 80% passing six inch mill feed and when no pebble crusher is present). WiBM is the Bond ball mill work index, unitless

Influence Of Feed Size On AG/SAG Mill Performance Mapping Orebody Hardness Variability For Ag-SAG Crushing And HPGR Circuits Modelling And Simulation Techniques Applied For Optimisation Of Mine To Mill Operations And Case Studies Modelling The Influence On Power Draw Of The Slurry Phase In Autogenous (AG), Semi-Autogenous (SAG) And Ball Mills ...

However, the performance of a SAG mill changes rapidly in response to conditions such as feed size and hardness, as well as longer-term variability due to liner wear – something no instrumentation can directly observe, according to the research centre.