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 from the distribution to calculate the top ball size
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Chat OnlineWe 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 hardwaresoftware’s behaviour Static ore was used to obtain the right sequence of image processing algorithms
However the finer feed size distribution consistently results in 50 higher throughput than the coarser one 1 10 100 100 1000 10000 100000 size microns cumpass SAG 1 feed SAG 2 feed
Scw solid concentration by weight fraction in the SAG mill feed Jb balls charge bulk fraction of the SAG mill volume NNc fraction of the SAG mill critical speed Pc SAG mill power consumption kW 6 00 1 00 of the fresh feed in the size range 152 25 mm
Secondary mill feed – Continuous regulation capability gate to allow controlled distribution of feed between the two ball mills Finally if the amount of critical size material removed from the mill is less than the crusher and secondary mills capacities those mills can also be fed with a small fraction of the SAG mill trommel undersize in
SAG mill throughput is often a bottleneck in increasing metal productivity Improved size distribution control in the mill feed can be used to increase mill production This can be accomplished by controlling blast fragmentation as a function of energy input and rock characteristics Such an approach requires the integration of rock fragmentation and comminution modeling
AGSAG mills for a given feed size distribution and feed rate Morrell and Morrison 1996 Hence when using JKSimMet in a design situation the dimensions of the AGSAG mill are adjusted until the load in the mill reaches 25 by volume when fed at the required feed rate The model predicts the
changes to feed size distribution through modification to blasting practices and primary crusher operation – socalled MinetoMill approach 32 MinetoMill The feed size to AG and SAG mill circuits has been demonstrated to have a significant impact on throughput with effects such a that illustrated in Figure 7 being commonplace Modifying
This value corresponds to about 15 steel in the SAG mill and a load of about 35 and represents the motor power required and the shell is sized to suit that power Lower steel and charge volume loads draw less power but the chamber will draw power up to this maximum load
The circuit capacity was increased from 270 tph to an excess of 395 tph with 50 to 60 of the ore crushed With an increased ball charge and load an average 38 MW of the 42 MW available power was recorded on the SAG mill At St Ives Gold Mine JKSimMet was used as a simulation tool
Feb 12 2018 · 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 SM4014’means it is a dry mill
VANCOUVER 2015 13 Page The final optimised layout of the Constancia grinding circuit used approximately 14 000 m3 concrete and 1300 t steel for 64 MW of installed power This compares with 14100 m3 concrete and 630 t of steel in the original DFS for 475 MW of installed power
The ball mill motor power requirement calculated above as 1400 HP is the power that must be applied at the mill drive in order to grind the tonnage of feed from one size distribution The following shows how the size or select the matching mill required to draw this power is
Feb 12 2018 · Development of SAG Process With the increasing of mineral processing plants scale and the demand for automation the manufacturing process and operation of SAG mill are more and more mature The running largest SAG mill is more than 13 meters in diameter the full automatic control of the SAG mill has already been developed and applied and now it is being gradually accepted and used in
sieving the material is the most accurate method of determining the size distribution of the agsag mill feed However fluctuations in feed size
THE APPROPRIATENESS OF THE TRANSFER SIZE IN AG AND SAG MILL CIRCUIT primary crusher product size distribution is reasonable size is the product of the SAG mill circuit and the feed
6 Model Predictive Control for SAG Milling in Minerals Processing Estimated Benefits • Improvements are expected as follows • Throughput increase 2 5 • Specific Energy Consumption decrease 2 – 5 • Particle Size Distribution variation decrease 20 30 This should also improve overall operation and downstream beneficiation through
• Joint Spacing 08 m • In situ Block Size 1103 m SAG mills require a certain ore feed size distribution to operate efficiently This feed is supplied to the SAG mill by the primary crusher Blast Model Calibration and taking this one step further back mill performance can be directly related to the fragmented size distribution from blasting
SemiAutogenous Grinding SAG Mill Wet or dry Higher capacity than AG mill grinding Primary coarse grinding up to 400 mm feed size Grinding media is grinding feed plus 412 ball charge ball dia100 125 mm High capacity short retention time Less sensitive to
stage SAG milling is likely to be a comparatively profitable grinding circuit design xMedium Grind – 80 passing size between 106 and 75 µm To mill in single stage SAG configuration the feed must be consistent and the downstream process reasonably capable of
can be practically conveyed and introduced into the mill The mill product can either be finished size ready for processing or an intermediate size ready for final grinding in a ball mill pebble mill or VERTIMILLTM Wet grinding is accomplished in a slurry of 50 to 80 percent solids AGSAG mills can accomplish the same size reduction work as two
Figure 2 lowsheet used for “Standard” ASA circuit simulations The specifications for the “standard” circuit are SAG Mill o inside shell diameter to length ratio of 21 with 15 ° cone angles o ball charge of 15 125 mm in diameter o total charge of 25 o grate open area of 7
A1 Results of size analysis for 16000 – 13200 microns coal using 306 mm balls 82 A2 Results of size analysis for 9500 – 6700 microns coal using 306 mm balls 82 A3 Results of size analysis for 2360 – 1700 microns coal using 306 mm balls 83 A4 Results of size analysis for 26500 – 22400 microns coal using 388 mm balls 83
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 Burger McCaffery McGaffin Jankovic Valery
Mill fresh feed particle size distribution was also determined using rod screens and laboratory screens Weight of these samples after drying was 75 and 105 kg Fresh feed flow rates for first and second stage sampling were 142 and 141 th that is almost two times of designed capacity
together with feed and product size distribution is necessary to optimize mill sizing and design for specific applications Using Outotecs combined expertise in grinding inhouse sizing programs and grinding database Outotec is able to accurately determine the correct mill type and size for any given application A thorough understanding of
operating their mill Factors such as mill speed mill inlet water feed size distribution and ore hardness all have an inﬂuence on the grindcurve and form an integral part of the optimisation process Test work has been conducted at a number of sites to develop grindcurves for different mills treating a
Feed size and blasting – CEEC – The Future The Coalition AGSAG mill feed size distributions are the result of how insitu rock has been blasted and These were
Some operations however have distribution of the agsag mill feed However fluctuations in feed size recognized an opportunity in the relationship between feed size and mill make such sizings valuable only if they can be done very frequently performance and manipulate feed size to obtain efficiency which is clearly impracticable in a
22 Ore size distribution measurement Ore size distribution is considered an important process measurement for SAG mills operation and control Both ore hardness and ore size distribution are the most important disturbances that a ect SAG operation and thus having information of