Mill speed can be adapted to upstream and downstream processes – avoids overgrinding, and optimizes load distribution between SAG and ball mill (Mular, Halbe & Barratt, 2002). Power consumption is influenced by load respectively torque and mill speed. This means that further energy can be saved if a mill speed below the rate speed is re-
different liner designs at different mill speed but with constant filling degree (30%). Indeed, as explained previously, at a mill stop, the measurement of ball charge filling degree could be undertaken and will provide the static media charge angle (βstatic = 143°). An online measurement of the similar angle (βdynamic), when the mill is ...
Ring Motors vary the speed of the mill by changing the sta-tor frequency. A cycloconverter provides variable frequency for start, stop and speed variation during operation. Figure 1: Ring Motor of the 38' SAG-Mill of Rio Paracatú Mineraçao; Brazil 3 Design Verification To assure reliability of operation the mechanical design must be verified.
Figure 3 provides the actual values of speed, torque and mill angle for a Frozen Charge trip at a large SAG mill for reference. The speed is following the preset speed ramp until the trip shuts of the motor and lets the mill oscillate. The torque value is constantly growing and the mill angle
Download full-text PDF Read full-text. Download full-text PDF. ... Ball mills and SAG mills, ... VF D control will al low a synchronous m otor to be optimally designed for a spec ific Mill speed.
Our SAG mill strategies automatically adjust feed rate, mill speed and water addition to reduce upsets, eliminate grind-outs, protect liners/lifters, and increase tonnage . We maintain desired operating conditions by constantly monitoring bearing pressure, mill power, recycle pebbles, mill density, charge toe and mill acoustics,
the gearless drivealso provides s opportunity to better trim the SAG mill speed and power to the downstream constraints and overcomes damage concerns associated with frozen ball charge. Review of the wear characteristics in the SAG mill discharge pulp lifters and the observations .
mill speed increases, initially on a straight line relations-hip and then at a diminishing rate as mill speed increases beyond a certain threshold • Constant torque capability of the motor at 1.0 per unit up to the rated mill speed (@ 74% C.S. for the 24 MW Base Case), and at 78% C.S. for the 25.3 MW Improved Base
mills, but the material is discharged mechanically by a discharge diaphragm. These mills are well-suited for finer feed materials. They are used for secondary grinding downstream of a primary grinding unit or in a combi-grinding system with a polycom ® high-pressure grinding roll. Air-swept mills are single-compartment mills.
• 28 MW GMD for a 40' SAG mill • 28 MW GMD for 42' SAG mill Whether it is size or an installation at the highest altitude (4600 m.a.s.l.), ABB's GMDs are well positioned to contribute to the building of larger and ever more powerful mills. — Leading the gearless mill drive evolution The ABB gearless mill drive (GMD) is the most powerful ...
Industrial Case Study Industrial Case Study ––SAG Mill: Status SAG Mill: Status •Mill Diameter : 9.7 m •Mill Speed : 69% C. S. •Power draw Installed : 16.6 MW •Power draw Operating : 15.3 MW •Liner Material : Steel •Number of Lifter Rows : 54 •Lifter Profile : Hi-Hi •Rock F80 Size : 75 mm •Rock Specific Gravity : 2.7
Mill operating conditions including mill speed (for circuits with variable-speed drives), density, and total mill load The effect of feed hardness is the most significant driver for AG/SAG performance: with variations in ore hardness come variations in circuit throughput.
adjust mill speed. • New rules for the expert system speed control: High LDL signal and low bearing pressure, reduce speed and prevent "metal on metal" operation. • Two vibration systems installed and in operation at Gold Corp Peñasquito on their two 2265 TPH SAG mils.
28 Call: 603‐654‐2550 | Fax: 603‐654‐2945 S t e e l S t a i n l e s s C a s t I r o n H i ‐ t e m p N F <.25% C >=0.25% C >=0.55% C >=0.25% C >=0.55% C WORKPIECE MATERIAL CUTTING SPEED (SFM) TIALN EXAMPLES This chart provides starting parameters for …
High-speed positioning function Setting of FAD + advanced preview feed-forward, position gain switching function, etc. Stop Setting of brake control, quick stop at emergency stop, etc. Unexpected disturbance torque detection Adjustment of …
AG/SAG mills in the data base are up to 40ft in diameter and ball mills are up to 26ft in diameter. The measured gross power draws ... – this covers mill dimensions, speed of rotation, whether the mill has cone ends and type of discharge mechanism. Dimensions can be input in either metric or imperial units by the use of the drop-
Optimising the capacity of your SAG mill is crucial to avoiding downtime and liner wear and damage. With variances in mill ore feed rate, mill speed and slurry density, critical impacts can occur in your SAG mill. The speed at which these variances are adjusted for is thus crucial for minimizing damage and optimizing liner life.
gearbox rotate the screw at a predetermined speed. Temperature controllers 1 section 1: introduction to extrusion. are connected to heating/cooling elements on the barrel to hold the tempera-ture at the set-point temperatures. The ability of the screw and barrel assembly
Figure 5-12 SAG Mill Operating Work and Critical Speed ..... 65 Figure 5-13 Bond Work Index of SAG Mill Feed..... 66 Figure 5-14 Power of Different Type of Liners at Different Speeds and 6 month Service Life .. 68 ... on mill speed and volume of the charge to estimate the ball charge shoulder angle (angle of the . 2
LG A mill power equation for SAG mills. Minerals and Metallurgical Processing. Feb 1990 pp57-62. Gross power No load power Net power drawn by the charge (8.13) The net power is calculated from Net power KD2.5L e! c./ Watts (8.14) In equation 8.14, D is the diameter inside the mill liners and Le is the effective length of the mill including the ...
The milling cutter rotates at 60 RPM in clockwise direction and width of cut is equal to the width of the workpiece. Draw a neat sketchof the milling operation describing aboveconditions. The thickness of the workpiece is 20 mm. If depth of cut of 2 mm is used then find out cutting speed and volumetric material removal rate (MRR
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.
rated mill speed into the speed of the motor, ω ratedasHz, which for a Gearless Mill Drive is simply ⌽ RPM ÷ 60. For a gear driven mill, the motor speed is a function of the mill speed ⌽ RPM, and the gear ratio of the mill bull gear and the drive pinion. Case study No 1: Changing pinion on a fixed speed mill
The reasons why these gearless drives on mills came about in the late 1970's is because of SAG mills requiring variable speed and the limitations of material of construction and the heavy manufacturing capabilities at the time. Girth gears have been going through enormous improvements over time following the use of FEA, casting software like
Table of Contents Publication 13M (DM-2) 2015 Edition - Change #1 TOC - 1 DESIGN MANUAL, PART 2 HIGHWAY DESIGN. TABLE OF CONTENTS . CHAPTER SUBJECT PAGE. CHAPTER 1 GENERAL DESIGN
Step 1: Mill overload power •Determine a set of operating conditions that reflects the maximum "overloaded" condition that the mill should be able to handle: –SAG mills: 20% v/v ball charge, 30% v/v filling and 78% critical speed with worn liners –Ball mills: 36% v/v filling and 78% critical speed with worn liners
revealed a thermal limitation in the 3000hp LCI variable speed drive system at low mill speeds. This event resulted in variable speed operation being suspended, and the mill being operated at a fixed speed (76% of critical) until a thorough analysis of the event could be completed. DEVELOPMENT OF A SAG MILL CONTROLLER
THE INFLUENCE OF MILL SPEED AND PULP DENSITY ON THE GRINDING EFFICIENCY 89 Pilot plant description The milling pilot plant consists of two containers mounted on top of each other (see Figures 1 and 2). The bottom container holds the mill, the drive train, rollers and the high-tension cabinet. The feed boxes (fine and coarse feed) are built into the
Modeling and Simulations two parallel primary grinding lines. Each line consists of a variable 4. Validation speed SAG mill measuring 28 feet in diameter by 11 ft long. The mill 5. Implementation motors are rated at 5,500 HP. At the discharge of each SAG mill is a pair of vibrating screens.
Figure 5.11 Power variation with mill speed for different media shapes (J=15%).86 Figure 5.12 Power variation with mill speed for different media shapes (J=20%).87 Figure 5.13 Power variation with mill speed for different media shapes (J=25%).87 Figure 5.14 Variation of mill power draw with mill filling, J (cylpebs media)…..88