Moreover, an increase in ore hardness corresponds to an increase in feed size. Hard ore grinding in the SAG mill resulted in finer products compared to the soft ore milling. In addition, it was found that the products of the soft ore milling were more elongated, angular and less rounded than those of the hard ore milling.
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.
This counter-intuitive effect may result from the positive effect of feed particle size on gizzard development. A more developed gizzard is associated with increased grinding activity, resulting in increased gut motility and greater digestion of nutrients.
Blasted ore is further reduced in size by primary crushers, semiautogenous (SAG) and autogenous (AG) mills. SAG mills have special requirements on feed size distribution, which is influenced by the size distribution of the blasted rock (Esen 2013).The 80% passing size, x 80, is regularly used to evaluate the energy draw in size reduction (Workman and …
SAG mills, Morrell (1993). The mill with scats had a considerably finer size distribution, and notably lacks ball in the 40mm to 60mm size range. This is the size at which the porosity is exposed, and they suddenly become smaller and non-spherical. For a normal finer ball size distribution a finer grind and lower throughput would be expected.
Methods of estimating SAG mill volumes, mill charges, feed size and power consumptions and optimum speeds of rotation during operation are described. The operation and mechanism of grinding and size reduction is explained with the help of solved mathematical examples. ... the original ore size and the size distribution. Increasing the ball size ...
The feed size distribution is also the implicit result of the ore competence (affecting blasting and crushing performance). This distribution affects the SAG mill load and the load affects directly the mill power and the efficiency of the mill operation (Van Nierop and Moys, 2001). If a SAG mill has been designed with a conventional power or ...
liner chuge sag mill - ZCRUSHER. Ø Effect Of Sag Mill Feed Size Distribution And Ore ... SAG Mill load during this liner cycle ranged from 800 to 1100 tonnes ... Further more the 52 row liner design ... Detail About.
The particle size distribution out of an HPGR is not "Bond-compatible" and the extra fines result in a phantom cyclone effect similar to a SAG mill. Moreover, there are reports of additional cracking within the matrix of the rock (microcracking), but that effect is probably similar to the phantom cyclone effect for modelling purposes.
the grinding media of autogenous mills derive from the feed ore size and composition (delboni and morrell, 1996) and the varying ratio of different components in the mill feed affects the mill charge and consequently the whole breakage process. after developing a new ag/sag mill model that describes the influence of mill charge composition on …
50%/50% SAG mill/ball mill power, the value of SAG mill/ball mill operating power may differ among operations. For a particular SABC operation, its optimal energy distribution should be determined with a comprehensive consideration of ore properties, mill feed size, required product size, and circuit operating parameters.
Total grinding power consumption decreases and SAG mill capacity increases significantly. Later tests, with other types of ore, have shown lesser differences between those size distributions. However, the effects on power …
The ROM ore size distribution is a function of the geotechnical properties (fracture frequency and Rock Quality Designation (RQD)). Hence, the feed size to the SAG mill is a function of rock competency (Axb) and rock fracture.
Then, the particle size distribution T2' can be determined by a simple mass balance, i.e. by subtracting a proportion of the final product (P) from the AG/ SAG mill product size distribution (T) as follows: Q2 = Q - Q1 [5] T2' = [Q x T – Q1 x T1'] / Q2 [6] Finally, the corrected Bond operating work indices for the AG/SAG mill and
The most recent version of the sag mill model was used and incorporates the effect of ball load, feed size and speed (Morrell and Morrison, 1996) as well as the effects of grate design (Morrell ...
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
Total grinding power consumption decreases and SAG mill capacity increases significantly. Later tests, with other types of ore, have shown lesser differences between those size distributions. However, the effects on power consumption and mill capacity have been the same, confirming the strong effect of small variations in the ultrafines production.
Ball mill Wi test closing screen size, umclosing, µm; Ball mill Wi test product size, P 80, µm; Ball mill Wi test feed size, F 80, µm; Ball mill Wi grams per revolution at test conclusion, gpr; Required parameters. F 80, µm is the 80% passing size of the fresh feed to the circuit (expected to be a Bond-compatible size distribution). P 80 ...
Application of High Pressure Grinding Rolls (HPGRs) and implementing hybrid comminution circuits (ie, HPGR-SAG mill) requires proactive control of the feed size distribution to each unit. Application of Vertical Tower Mills (VTMs) and other fine grinding equipment to achieve a finer grind size, while maintaining the throughput, requires ...
Improved particle size analysis enables finding the best particle size shape for the SAG mill feed. The ore feeders are balanced using the particle size distribution shape as the controlled variable. As such, the bin or stockpile natural segregation is balanced properly using this online estimate.
As all ex- primary crusher ag/sag mill feed size distributions are the result of how in-situ rock has been blasted and subsequently treated by the primary crusher, it is reasonable to expect that by changing how blasting is carried out and how the primary crusher is operated significant changes 10 can be made to the distribution.
In this case the size distribution is used as a "disturbance variable" in a model predictive controller for a SAG mill. The model can predict by up to 100 seconds in advance the effect on the SAG mill weight. This has greatly improved the stability of the grinding circuit as well as increased the energy efficiency of the Mill.
This work is aimed at optimizing the SAG mills feed size distribution as this is an important parameter that affects milling performance after ore competency. A lot of operations have recognized the optimization opportunity that can be taken advantage of by manipulating the feed size distribution to improve SAG milling efficiency.
SAG Mill Circuit Example — Gold Processing SAG mill circuit example for gold processing [image: (135-6-3)] AG/SAG Mill. AG/SAG mills are normally used to grind run-off-mine ore or primary crusher product. Wet grinding in an AG/SAG mill is accomplished in a slurry of 50 to 80 percent solids. 2D and 3D simulations of particles in a SAG Mill
system. The ore from the trial blast was campaigned through the mill without any All samples were processed through the lab to determine % solids, and blending and a full mill survey was conducted. SAG mill throughput was size distribution. Portions of the sized SAG mill feed were collected and maximized at 673 dmtph of fresh feed.
The size distribution of the fresh feed as well as the ball size distribution are also known to have important effects in the process (Napier-Munn et al., 1996). Finally, more recently, the full secondary pre-crushing of the fresh feed to the mill has also been considered a valid alternative to improve throughput of SAG mills ( Siddal and ...
Ball Mill Power Calculation Example #1. A wet grinding ball mill in closed circuit is to be fed 100 TPH of a material with a work index of 15 and a size distribution of 80% passing ¼ inch (6350 microns). The required product size distribution is to …
To study the effect of liner profile on performance of the SAG mill the following assumptions are made: 1. Size distribution and hardness index of feed (i.e. A × b and ta) are constant over the whole life of the liner. 2. Plant throughput increases linearly over the liner life. 3.
"The control of the operation of semi autogeneous grinding (SAG) mills is mainly achieved through adjustments of feed rate, water addition and speed of rotation. With the introduction of image based sensors it is possible to have on-line measurements of the size distribution of the ore feeding a SAG mill.
The CI measurement is not used directly in the power modelling; it is used to predict the particle size distribution (F 80 and F 50) sizes of the SAG mill feed. The net effect of adjusting the particle size distribution is similar to what is observed in the Bond/Barratt model by adjusting the crushing work index which dictates the hardness of ...
The purpose of the primary crusher is to reduce the ROM ore to a size amenable for feeding the secondary crusher or the SAG mill grinding circuit. The ratio of reduction through a primary crusher can be up to about 8:1. Feed: ROM up to 1.5 m; Product: -300mm (for transport) to -200mm (for SAG mill) Feed Rate: 160 to 13,000 tph
Figure 2 shows SAG and ball mills breakage rates. Note that the curve ex-hibits the classic behavior of a SAG mill curve, showing the effect of the ore as the grinding media in coarse particles and the effect of balls, which begins to appear in the 50 mm particle size, having its greatest point at 7 mm. For all mills, the breakage rate indicates a
The effect of feed size is marked, with both larger and finer feed sizes having a significant effect on throughput. With SAG mills, the response is typically that for coarser ores, throughput declines, and vice versa.
Highlights Ore effects on the product shape were studied in order to monitor breakage events in SAG mill. The quantitative shape properties were fitted well to the 3-parameter lognormal distribution. An increase in ore strength corresponds to a decrease in product size, angularity and elongation. By increasing ore hardness, the main breakage event changes from impact to …
We describe here one of the very first pioneering SAG Mill Feed Particle Size Analysers: A set of preliminary experiments was carried out in order to assess the hardware-software's behaviour.Static ore was used to obtain the right sequence of image processing algorithms. The camera was installed 3 mts away from the commercial sizer over the feed …
Feed Size Distribution. Each comminution line, lines A to E, were modeled separately since there are variations in ore source as well as milling technology (AG vs SAG) and mill size for each line. Monthly composite size distribution data for each line was used to develop a flotation feed size model.
In the SAG mill testwork, parameters such as: ore feed, size distribution and classification size are varied. If necessary, pebble crushing or mill speed changes would also be investigated. The testing procedure results are evaluated according to feed rate, power draw, and product size analysis.
reliance of ag/sag mills on the feed ore for their grinding media competence and size. Ag mills are the most sensitive in this respect with sag mills …
