The laboratories have a standard way of reducing the coarse material to the (roughly) 10 mm size used to feed the test that will not introduce excessive fines. Test Inputs When Wi RM is used to size SAG mills, the Bond/Barratt model assumes a 14# Tyler (1180 µm) closing mesh size — the engineer should specify this closing mesh size to the laboratory performing the tests.
COPPER MOUNTAIN: OVERVIEW ON THE GRINDING MILLS AND THEIR DUAL PINION MILL DRIVES ABSTRACT This paper will first give a short overview of the Copper Mountain project in British Columbia, which just has started commercial operation earlier this year. The grinding process with one 34' x 20' SAG
Autogenous mill and semiautogenous mill. While AG mills operate without a ball charge, SAG mills use a grinding media charge of normally 3 % 12 % for comminuting the feed material. The maximum feed size is between 200 mm and 500 mm. The AG/SAG mill is normally installed upstream of a tube mill operating in closed circuit with hydrocyclones.
In addition to the new process equipment, the SAG mill was commissioned with all controls implemented on the new PLC software platform. This removed the control strategy limitations previously described. Additional mill control loops and measurements now included: Mill feed tonnage (automatic PI control – operator or remote setpoint from mill
There are two parts to SAG mill design best practices. First is to choose the SAG mill (chamber size and power discussed above) that will process the design feed every day, including those days when mostly hard ore is available. Second is to engineer the grinding plant so that optimization can be done quickly.
Scw = solid concentration by weight fraction in the SAG mill feed; Jb = balls charge (bulk fraction of the SAG mill volume); N/Nc = fraction of the SAG mill critical speed; Pc = SAG mill power consumption (kW); % −6″ +1″ = % of the fresh feed in the size range −152 +25 mm.
feed size distribution, each SAG mill will process between 700 and 3000 tph. The budgeted average total throughput is 88,000 tpd. THE OK TEDI ADVANCED CONTROL . SYSTEM IMPLEMENTATION The SAG expert system at Ok Tedi was . completed in 1999, described previously by McCaffery, Katom, and Craven (2001). It runs within the MET (MinnovEX Expert
Figure 8: a) The primary mill dynamic models with product grind and b) the model uncertainty for these grind models. Feed Size (% 45 mm): A feed size increase of 1% in the passing 45 mm aperture range resulted in a steady state reduction of % passing 75 µm in product grind.
Optimization of the Design of SAG Mill Internals Using High Fidelity Simulation by John A. Herbst Svedala Optimization Services and ... (per unit length of mill) beginning at the feed end of the mill (slice 1) and proceeding to the discharge end (slice 17). ... The selection of an optimum top ball size for a large SAG mill is determined by ...
The PTI 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.
Modelling SAG milling power and speciﬁc energy consumption including the feed percentage of intermediate size particles M. Silva, A. Casali⇑ Mining Engineering Department, Universidad de Chile, Beauchef 850, Santiago, Chile
IsaMill Operating Principles. For example, grinding a pyrite concentrate so that 80% of the particles are less than 12 µm ( mm) consumes over 120 kilowatthours per tonne (kWh/t) of ore in a ball mill using 9 mm balls, but only 40 kWh/t in an IsaMill using a 2 mm grinding medium.
Sag Mill Discharge. This strategy will ensure significant increases in throughput, typically anywhere from 5% to 16% has been observed. Each milling circuit is unique, and as such the goals and most optimal control strategy might differ for individual cases. Process IQ is an expert in implementing control systems for SAG and Ball milling circuits,...
SAG specific power range of about 3 to 9 kWh/t for this site. The design of the ore stockpiling and conveying system contributes to fluctuating size distribution with significant shortterm segregation occurring under certain operating situations. Depending on ore type and feed size distribution, each SAG mill will process between 700 and 3000 tph.
Oct 10, 2016· "Although it is well known and easily experienced that the feed size distribution influences the throughput and stability of operation of a semiautogenous grinding (SAG) mill, the details are poorly understood since it is often only the input and output measurements that are used to identify unfavourable inmill conditions.
Model Predictive Control for SAG Milling in Minerals Processing | 5 Model Predictive Control on a SAG Mill and Ball Mills The solution for the SAG Mill is an adaptive controller which controls mill load using direct mill weight measurement or indirectly from bearing oil pressure.
APPLICATION OF THE MINNOVEX SAG POWER INDEX AT FIVE CANADIAN SAG PLANTS ... • SAG Mill Size cm (1 ft) diameter by mm (4 inches) long ... The use of small (30 to 40 kg) samples of fist sized pieces to represent SAG mill feed is an innovation and, at the same time, an integral part of the cost effective use of the laboratory SAG ...
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 MW of the MW available power was recorded on the SAG mill. At St Ives Gold Mine JKSimMet was used as a simulation tool.
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 m; Product: 300mm (for transport) to 200mm (for SAG mill) Feed Rate: 160 to 13,000 tph
the size distribution of the SAG mill feed can be regulated (to some extent). The feedrate isusually automatically controlled by adjusting the speed of one or more of the feeders. It is quite common to have one feeder being adjusted automatically to control feedrate to the mill
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. SM40*14'——means it is a dry mill.
I203 INFLUENCE OF FEED SIZE ON AG/SAG MILL PERFORMANCE 1, Isles Road, Indooroopilly, Qld 4068, Australia email :
Feed Size, F80: Primary crushed ore is mandatory to feed any SAG mill. Typical feed size range is 80% passing 130 to 160 mm. Softer ores will be a little finer but the finer size is not sustainable when the ore becomes hard. Precrushing to finer sizes enhances throughput as does crushing of pebbles from the SAG mill (usually minus 60 mm).
The 40foot (40') SAG mill now receives a feed of predominantly high pressure grinding rolls (HPGR) product with a minor component of secondary crushed ore at a combined F80 of 17 mm. The significant reduction in feed size to the SAG mill has markedly changed the operating characteristics of the mill, which has been extensively studied since commissioning in 1998.
The Std. JK size distribution is that taken from ball size distributions measured from dumping and sizing the whole charge of production 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