Effect Of Sag Mill Feed Size Distribution And Ore

Size does matter - SAGMILLING.COM

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 ...

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Effect of ball and feed particle size distribution on the ...

In this article the effect of grinding media size distribution and feed material particle size distribution (PSD) on the product fineness requirements were investigated. A model free approach called the Attainable Region method was then applied in order to optimize the product size fineness in terms of the feed size and ball mix.

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Metallurgist Training Modules

representative of the size distribution (Gy's Formula). • Samples must also contain at least 300g solid if screen sizing is required. • Unless assaying of size fractions is required, laser sizing is usually adequate for very fine distributions. • Samples of excessive size slow down lab …

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Feed Size VS Ball Size - Grinding & Classification ...

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 …

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AMIT 135: Lesson 5 Crushing – Mining Mill Operator Training

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

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- Test methods for characterizing ore comminution behavior ...

size distributions and specific grinding energy when decreasing mill size by the factor 1.63. A detailed description of the novel geometallurgical comminution test (GCT) is given. With respect to ore crushability and autogenous and semiautogenous grinding (AG/SAG) also drop weight tests were conducted. For a more accurate and precise

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Autogenous and Semi-Autogenous Mills - ScienceDirect

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 ...

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Multi-component AG/SAG mill model - ScienceDirect

In this research, the feed ore properties including hardness and particle size distribution was applied in order to improve the AG mill operation. In the regard of particle size distribution, the amount of materials coarser than 200 mm in the feed of a full-scale AG mill was increased by direct addition large lumps of ore (200–500 mm).

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Evaluating the effect of feed particles size and their ...

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 mill, prediction of energy required, and product size distribution for complete grinding in AG and SAG mills. In this study, the effect of initial ...

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How HPGRs compare to conventional milling

As a result, ball mills produce a rather wide particle-size distribution (PSD), requiring additional work downstream, while rod mills achieve a lower PSD but produce a coarser product. By comparison the inter-particle compression in a High Pressure Grinding Roll has a more even effect on the entire feed, resulting in a high ratio of fines ...

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Liners for the Grinders | E & MJ

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.

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SAG Mill Ball Sizing - Grinding & Classification Circuits ...

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.

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Break it Better - Mine Blast Fragmentation - International ...

Further into the comminution circuit, being able to adjust the SAG mill feed based on realtime data has allowed operators to optimise the size of material going into the SAG. This, in return, has increased the throughput at many operations worldwide, and …

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FREDA REBECCA SAGMILLING CIRCUIT OPTIMIZATION

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.

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Analysis of the Effects of Blasting on Comminution Using ...

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 …

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Mineral Processing Plant Design

variations in ore characteristics, size distribution, moisture content, ore grade and ... on both greenfield and retrofit projects, to increase feed rate to the SAG mill. In other words, crushing plants, from primary to quaternary circuits, ... Maximum rock size in the feed Ore types, compressive strengths and abrasion indices

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(PDF) Influence of feed size on AG / SAG mill performance

The efficiency of the mill to break ore is a function of both the feed size distribution and the relative hardness of the ore. When the feed size of a SAG mill becomes coarser, i.e. α …

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STARTLING EFFECT OF BALL SCATS REMOVAL ON SAG …

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.

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(PDF) Exploring the effect of blast design on SAG mill ...

For rocks which are in between the css and oss in size a probability exists for them to either remain or pass out of the crusher Semi Autogenous Milling 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 ...

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(PDF) Influence of feed size on AG/SAG mill performance ...

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.

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Ø Effect of SAG Mill Feed Size Distribution and Ore ...

SAG Mill I-12 Ø Effect of SAG Mill Feed Size Distribution and Ore Variability Ø Mill liner design modifications, and Ø Circuit Design Considerations That Influenced Throughput

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The influence of mill speed and pulp density on the ...

THE INFLUENCE OF MILL SPEED AND PULP DENSITY ON THE GRINDING EFFICIENCY 91 Graph 2. Particle size distribution for different mill speeds 68.8 % solids 73.4% solids 75.9% solids Ore solids density 3.1 3.1 3.1 Dry feed rate (kg/h) 289 288 287 Speed (rpm) 35.31 35.11 35.00 % Vcrit 75.59 75.17 74.92 Absorbed power (kW) 5.335 5.628 5.338

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Control of Size Distribution of the Ore Feeding a Semi ...

"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.

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Crushing SAG Mill Critical Size Material

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.

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The Effect of Aspect Ratio on the Grinding Efficiency of ...

energy of AG/SAG mills under all normal operating conditions, eg ball load, mill speed, feed size and ore hardness and for all normal aspect ratios and mill sizes (Morrell, 2006). The equations are semi-empirical and are based on data from 43 different circuits and 70 …

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Exploring the Effect of Blast Design on SAG Mill ...

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 ...

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AN OVERVIEW OF SINGLE STAGE AUTOGENOUS AND …

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

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Modelling SAG milling power and specific energy ...

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 ...

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Minerals | Free Full-Text | Optimizing Performance of SABC ...

This causes a higher variation in the feed rate and particle size distribution in the feed to the SAG mill, which results in a greater variation in the SAG mill power draw in the transition period when the pebble crusher is in operation or not. ... the feed ore is essentially fully ground within the SAG mill. This causes a lower production rate ...

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Size distributions for the RoM ore and SAG mill Feed ...

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 ...

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THE COMMINUTION CIRCUIT DESIGN FOR THE CONSTANCIA …

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.

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Application of Operating Work Indices in Autogenous ...

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

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(PDF) Exploring the Effect of Blast Design on SAG Mill ...

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 ...

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Why should I optimize my grinding or flotation plant ...

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.

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