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SAG is an acronym for semiautogenous grinding. SAG mills are autogenous mills that also use grinding balls like a ball mill. A SAG mill is usually a primary or first stage grinder. SAG mills use a ball charge of 8 to 21%. The largest SAG mill is 42'' () in diameter, powered by a 28 MW (38,000 HP) motor.

The poles of the gearless or synchronous motor (also called wraparound motor or ring motor) are directly installed on the pole flange of the mill shell, turning the mill body into the rotor. The stator is then wrapped around the mill. The gearless motor is fed by a cycloconverter which has a rated output frequency of around 5 Hz for the GMD drive.

ABB''s scope of supply includes two GMD systems for 38 foot 23 mw SAG mills (Fig.) comprising transformers, ring motors and complete containerized electrical houses (ehouses). The variable speed drive solution allows for optimization of the grinding processes for ores with varying properties and different mill loads.

Our GMD eliminates all mechanical components of a conventional mill drive system, such as ringgear, pinion, gearbox, coupling, motor shaft and motor bearings: By mounting the rotor poles directly onto the mill, the mill itself becomes the rotor of the gearless motor.

Gearless Warp Around SAG Mill. Previous Next. View Larger Image; For almost a decade now, very good operating experiences have been gained with a total of 28 gearless ring motor drives in the cement industry, driving tube mills with diameters of to 4 meters with drive powers ranging from 3000 to about 5000kW. ...

Sep 10, 2014· Literature Review: Gearless Motor Failures – A Mill Designer''s Viewpoint admin 10 September 2014 2014, Ball mill, Design, Design Validation, Failure Analysis, Gearless Mill Drives, Grinding Mills, Literature Reviews, Mill Design, Mills, Ring Motor, SAG mill, Stiffness, Strain Gauging, System Analysis, Vibration, Welding

Ball Mills as secondary grinding stage. The Electric Drive (SIEMENS) consists a HP synchronous motor of variable speed. General Description of the Drive The SAG Mill Drive is mainly formed by a 11,000 HP. Ring Type Synchronous Motor of double winding, fed .

Gearless Mill Drive (GMD) systems are characterized by having the motor wrapped around the mill like a ring. For this reason, they are often referred to as ring motors. The rotor poles are attached directly to the mill (head) flange, and hence the rotor becomes an integral part of the mill, as shown in figure 4.

Sep 28, 2014· Introduction. We have written on risk associated with large ring motors in gearless mill drives previously [1, 2, 3]. In [1], we observed that ABB and Polysius were far too confident in 2001 when they claimed that 42 and 44 ft diameter mills and ring motors posed only manageable risks and that a 44 ft mill and GMD design was ready and waiting for a purchaser [4].

Mar 14, 2006· For the two oregrinding mills, Siemens is supplying gearless ring motor drive systems supplied with power via cycloconverters. The SAG mill has a diameter of 38 feet ( meters) and will be equipped with a 18 megawatts drive system.

As a trusted mining partner, SIMINE solutions help customers to meet their challenges and thereby enable to set new benchmarks within the mining industry. To boost efficiency and reduce costs, we rely on our solutions for mine hoists, bulk material handling, gearless and conventional mills as well as miningspecific automation and power solutions.

When it Comes to Mining, Bigger is Best Gearless mill drives may be the key to maintaining throughput. Venkat Nadipuram. One of the key challenges in the mining industry today is maintaining throughput in the face of ore grade quality that has declined by 40 percent in the last decade.

The comparison of a conventional drive train to a gearless drive for a grinding mill is shown in Fig. 1. Figure 1 – Top view of SAGMills with alternative drive options; left side: dual pinion drive including motor, gearbox, pinion and girth gear; right side: gearless ring motor What''s the benefit?

The Siemens 42ft Gearless Mill Drive, still an evolutionary design approach? (SAG Conf. 2015) Optimization of the drive system for a cyclone feed pump (SME 2015) Increasing availability through advanced Gearless Drive Technology (CMP 2014) Design and dynamic behavior of large ring motors for grinding mills (SMMH 2012)

Preprint 13050 UPDATES ON GEARED VS GEARLESS DRIVE SOLUTIONS FOR GRINDING MILLS R. Kalra, CITICHIC Pty Ltd, Sydney, NSW, ... Among the many reasons that geared drives on large SAG mills are not favoured, is due to not having an efficient variable speed drive ... interface between the mill vendor and the gearless motor supplier.

ABB to deliver three large gearless mill drives for Mauritanian gold mine project ... ring motors and Ehouse. One 26 megawatt GMD system will be installed for a 40foot diameter SAG mill, while two megawatt GMD systems will be installed to drive two 27foot diameter ball mills. ...

Marsh 1 WHY shift to the gearless drives in mineral processing ??? Mill size – grinding economies of scale Relative lifecycle cost Lower power consumption Robust design Avoiding critical open gear power trains Variable speed Compatibility with processing plants Engineering design efficiencies Availability Minimal downtime

For grinding of the ore, an SAG (Semi Autogenous Grinding) mill and a ball mill will be used. For the two oregrinding mills, Siemens is supplying gearless ring motor drive systems supplied with power via cycloconverters. The SAG mill has a diameter of 38 feet ( meters) and will be equipped with a 18 megawatts drive system.

Today, 40 ft. diameter SAG mills and 30 ft. diameter ball mills, both with motor powers of more than 22 MW, are commonplace as mine operators look for even larger equipment to achieve greater economy of scale. Mills with these larger drive capacities are driven exclusively by a "wrap around" ring motor (gearless mill drive).

ABB is buying Alstom''s ring motor business to enhance its gearless mill drive (GMD) activities. The business, based in Bilbao, Spain, has about 120 employees and achieved a turnover of €57m in 2012/13. It will become part of ABB''s Process Automation division. The financial details of .

Ring gear drives huge grinding mill. ... SAG mills can operate at a fixed speed or adjustable speed through the use of ac synchronous motors or dc motors. ... and a ring motor (gearless drive ...

We provide optimized mill drive solutions for all types of ringgeared mills: low and high speed, single and dual pinion, with and without a gearbox — all designed for .

Mills and GMDs Maarten van de Vijfeijken* looks at large, larger and the largest units in grinding ore T he gearless motor (also called wraparound motor or ring motor) is a very large synchronous motor. The poles of the motor are directly installed on a pole flange on the mill shell: this means the mill body becomes the rotor. The stator of the

Giant ABB drive systems boost mining productivity . Orders for ABB gearless mill drives – giant motor and drive systems that enable mines to grind vast amounts of minerals and ore are at record levels as the mining industry seeks to boost production to meet the global boom in demand.
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