effect of grate discharge area of sag mill

Moys (1986) reported a model for the effect of flowrate and viscosity of the slurry on the hold up of the slurry in a grate-discharge grinding mill. Powell, Morrell and Latchireddi (2001) expressed later the Marchand "k" constant as an empirical function of the open area, grate design, mill speed,

Process. 46 (1996) 53-72 Slurry discharge capacity of autogenous and semi-autogenous mills and the effect of grate design S. Morrell, I. Stephenson Julius Kruttschnitt Mineral Research Centre (JKMRC), Isles Road, lndooroopilly, Qld. 4068, Australia Received 17 March 1995; accepted 20 June 1995 Abstract A laberatory based study of tumbling mills ...

Converting a mill from an overflow to a grate discharge arrangement leads to an increased power draw. This happens because the installation of the grate discharge arrangement enables the mill to run with a lower level of slurry due to it being no longer necessary for the slurry to build up inside the mill until it overflows from the mill discharge.

AG/SAG-Ball mill experimental flow sheet with sampling points 2.3. AG to SAG Conversion Mill Design During the industrial experiments two discharge grate apertures: 15x30 mm and 30x42 mm have been tested. In addition, an appropriate rubber liner and lifters (Figure 2) and steel balls – 100 mm in diameter (8% ball charge volume) were provided.

Different combinations of SAG mill ball charge and grate open area were tested until 2006. A higher load level was achieved after several changes in the grate design that prevented both liner and grate breakage. Upon resolution of issues related to the mill grate design, the project achieved the target throughput of 41 kt/d. Phoenix

Discharge grates are one of the most important parts of SAG mills. These grates prevent balls and unbroken ores from discharging the mill and they have a significant effect on the mill filling and size distribution of the discharge flow. To consider the effect of openings of the grates on the overall efficiency of the comminution operation, the variation of the grates shape and size were ...

effect of grate discharge area of sag mill grinding. Operation of SAG Mills Principle Operation of Semi Once the slurry has made its way via the grinding media charge, its first stage of discharge is via the grate Hence, in the absence of any subsequent restriction, the maximum flow capacity that can be obtained for a given mill is determined by the grate.

A Discrete Elements Method (DEM) study of load movement within a SAG mill 12,192 × 7620 (40′ × 25′) in normal operating conditions is performed. The purpose is to determine how the geometry of the lifters affects the kinetics of the load inside the mill. Specifically, the changes produced by the incorporation of inclined lifters and spiral or helicoidal pulp lifters to the kinetics are ...

Grate Discharge Sag Mill. ball mill discharge screenow to calculate the ball mill discharge size distributionand the ball mill discharge combine, in grate discharge type ball mill, a grate is provided at the discharge end of shellthe sag mill discharge is screened on a rotating trommel screenall load, mill speed, trommel screen aperture, pebble.

crusher, Table 3. The interior of the mill is illustrated in Figure 1, showing the length and filling of the mill, and low lifters on top of standard AMS grid type liners. The detail shows sections of the discharge grate (18mm round holes extending to near the centre of the grate), and pebble ports (75mm round holes).

Furthermore, the spider and discharge cone are segmented and removable. Together these solutions minimize the time and cost associated with mill relining and discharge-end servicing. Optimized discharge-end serviceability is particularly important for an open-ended mill as the grate design is the primary mechanism to control the slurry pool level.

Metallurgical Plant Design and Operating Strategies (MetPlant 2011) 207 8 - 9 August 2011 Perth, WA Surveys of the mill during the second liner life will remove the uncertainty about the variance in discharge function by providing a series of surveys on a mill with the same grate design throughout, and will also allow the effects of grate wear ...

efficiency vector, ci (fraction), which includes two effects: one produced by the mill's internal grate and the other by the pulp evacuation system (Magne et al., 1995). Thus, ci is defined by: i i * i p 1-c = p (11) Where: pi is the product flow rate from the mill and pi* is the …

Grate discharge Dry Grate discharge Wet Overflow discharge Wet Figure 8.5 Effect of mill filling on power draft for ball mills. The data is taken from Rexnord Process Machinery Reference Manual, Rexnord Process Machinery Division, Milwaukee, 1976 The effect of varying mill speed on the power drawn by the mill is shown graphically in Figure 8.4

On account of the SAG mill discharge grate characteristics, ... Q m =6100J pm 2 γ 2.5 Aφ −1.38 D 0.5 where A is the total discharge grate open area (m 2), ... Effect of grinding media and NaHS on copper recovery at Northparkes Mine. Minerals Engineering, 13 (13) (2000), pp. 1395-1403.

Based on experience, mill-liner designs have moved toward more open-shell lifter spacing, increased pulp lifter volumetric capacity, and a grate design to …

Understanding the effects of liner wear on SAG mill performance. ... discharge grates were made adding to the noise of the data set. ... grate open area fraction was equal for all three surveys at ...

Designed specifically for large and medium SAG and AG mills, the THUNDERBOLT MAGNUM 2000 delivers an incredible 2,000 joules per blow 70 times a minute to plough through the toughest of knock-in phases, such as tough, stuck and deeply-wedged liner bolt bolts at a mill's discharge end or breaking-in shell liners on the first inch, with ease ...

SAG Mill Circuit Example — Gold Processing SAG mill circuit example for gold processing [image: (135-6-3)] AG/SAG Mill. AG/SAG mills are normally used to grind run-off-mine ore or primary crusher product. Wet grinding in an AG/SAG mill is accomplished in a slurry of 50 to 80 percent solids. 2D and 3D simulations of particles in a SAG Mill

The discharge typically contains "negligible +12.7-mm material." At the time, "tonnage was 45 metric tons per hour (mt/h), and mill power draw was 709 kW," the study said. "Approximate circulating load was 550%." The experiment design used mill scats and paint, a collection screen, salt and a water-conductivity sensor.

Vulco™ discharge grates have ˚exibility in sizing, shape and location of apertures. Options range from small multiple apertures per grate to large SAG/AG mill applications with integrated reinforcement for structural integrity with open pebble ports for maximum open area. Vulco® mill linings are available for small regrind

The discharge end of the Grate Discharge Ball Mill has at least ten times the discharge opening area, through the grate slots, compared to the common trunnion overflow type mill. The discharge grates are designed to run clean and free of any blinding or choking. The pulp level in the mill may be varied by merely changing the pulp dilution.

Figure 2 - Crash stop of SAG mill showing pooling . The mill grate discharge included square pebble ports which hadvery limited open area at the periphery. This added to the pooling effect. The team was able to reconfigure them into a slotted arrangement parallel to the direction of rotation while maintaining the original 7.0 cm (2.75 inch)

of grate/pulp lifter design in AG/SAG mill discharge. The current understanding from literature lacks knowledge of mill content size distribution and its effect on discharge through the grate at various aperture sizes and radial positions. It also indicates that in order to advance the understanding in a meaningful way, a more mechanistic ...

A real-time monitoring system to monitor the wearing in the thickness of the ribs ( 5 ) of a grate ( 1 ) of a SAG mill ( 9 ) due to the abrasive action of the ore pulp residing inside the mill and due to the action of the grinding elements during the operation, and which in certain cases also generates obstruction of the slots ( 4 ) due to the jamming of said grinding elements inside the slots ...

Overflow discharge ball mill can grind ores into the size under 0.2 mm, so it is very suitable for the second grinding system. The capacity of it is about 15% lower than grate discharge ball mill in the same specification, and the loaded grinding medium is also less than that one. Rod mill Fote rod mill It can be divided into three types of rod ...

The impact of the shape representation used for rock particles in a DEM model of a SAG mill on charge dynamics and energy utilisation is investigated. A 1.8-m diameter pilot scale SAG mill which includes realistic end walls and a discharge grate is used. This size of mill is used for scale-up and design processes for industrial SAG mills so understanding the effect of approximating the ...

As a result, mines have shifted their emphasis in optimization from ball mills to SAG mills. The rock load in the mill essentially depends on ore characteristics and the discharge rate of broken particles through the discharge end. The discharge rate depends on how efficiently the discharge pump (grate and pulp lifters) operates.

He chose to replicate a SAG mill modeled with a grate discharge for his design, using only the actual liners and grate ends components in the simulation itself. He then set up a series of Rocky cases that filled up the mill with particles and steel balls to varying levels and then rotated the mill at …

• Shell supported mill discharge systems • Larger liner handlers to ha ndle heavier liner sections • Improved materials Operating techniques, too, have improved markedly. Advances have been made in understanding the effect of feed size on mill capacity, with secondary crushing now commonly adopted for very competent ores.

The material of SAG mill liners are low C or high C Cr-Mo Alloy steel,which depends on the specific working condition of the SAG mill; Chromium and molybdenum both individually increase the hardenability of low alloy steel. Important synergistic effects, not yet fully defined, can also occur when Cr and Mo are used in place of single elements;

Pegging of the discharge grates in SAG mills often occurs and this will result in a drop in throughput. The effect of new grates can be simulated in terms of new open area, size …

The discharge rate depends on how efficiently the discharge pump (grate and pulp lifters) operates. Similar to the impeller design affecting pump capacity, the pulp lifter design affects the discharge capacity (or mill throughput) of AG and SAG grinding mills.