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How A Grate Discharge Ball Mill Works . How does a grate discharge mill work. How a Grate Discharge Ball Mill Works. Here I try to explain how ground slurry is discharged from a grate ball mill or SAG. How it works is, the slurry flows across the grate as it would a screen panel. On the other side of the gratescreens are veins like a pump impeller.

Apr 14, 2016· An increase in slot size and operational stability has increased throughput by 7%. Pebble production increased by 24% during the first 50 days of operation, while the wear rate decreased from 0.26 mm/day to 0.11 mm/day. Mill availability has increased thanks to …

The software uses the particular power model (Bond/Barratt, Morrell Mi, etc.) to determine what is the transfer size where the ratio of E SAG to E ball matches the ratio of mill power (1:1.5 in this example). This is the 'maximum efficiency' transfer size where the mills will both operate at full power.

Each time the grate enters the mill charge, the horizontal force of the load in the mill deflects the grate. This stretches the rubber and forces any large material caught in the grate opening along through the grate slot. As the grate leaves the charge, the rubber assumes its original shape.

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 ...

grate slots, they get an equal chance to go back into the mill as illustrated in discrete element method (DEM) simulation of 36 ft SAG mill pulp lifters shown in Figure 5. Solid particles and coarse pebbles also flow-back through the grates along with the slurry. While flow-back of slurry leads to

• Mill size (diameter, length) • Maximum ball top-up size • Mill rotational speed (rpm, variable or fixed speed, single or dual rotation) • Ore type (abrasivity of the ore) • Mill discharge type (grate discharge mill, overflow mill) • Available drilling pattern • Total filling degree (ore and balls) FAG & SAG Main design parameters:

Typically, a SAG mill based circuit (P80 of 106 to 150 um) has media costs of around A$1/t. Providing the ore is amenable, the use of primary autogenous milling can reduce this cost by 40%. Autogenous milling is typically practiced in association with

representative of the whole grate. [slot] all slots mill slot area x r Rel. Radial Posn. = total open area x R ∑ Equation 1 R mill = mill radius to liner plate R slot = radial dist to centre of ...

SAG mill discharge screen Vibrating Screen A 8 Ausenco selection SAG Mill screen opening, top/bottom mm 25/15 A 8 Ausenco selection SAG Mill grate slot opening mm 50 A 8 Ausenco selection Spray water volumetric flowrate m3/h 33 A 8 Ausenco selection Ball Mill (Secondary Grinding) No. of Ball Mills # 1 A 1 1297650100-REP-R0002-03.1 - 2013 Arctic ...

4.4.5. Interception Capacity of Inlets In Sag Locations Inlets in sag locations operate as weirs under low head conditions and as orifices at greater depths. Orifice flow begins at depths dependent on the grate size, the curb opening height, or the slot width of the inlet. At depths between those at which weir flow definitely prevails and

applied to the pilot plant data when selecting the SAG mill shell and motor size. Upon resolution of issues related to the mill motor and lifter design, the project only just managed to achieve the target throughput of 17 Mt/y (Figure 1). The contributing factors to higher than expected SAG mill specific energy (lower throughput) were:

The design of mill liners and SAG mill discharge grates will have a large effect on how efficiently the mill operates and the circuit throughput. All models generally assume that a mill is fitted with "efficient" liners and that the grate design neither limits passage of pebbles (and pulp) nor permits re-circulation of pulp back into the mill.

The load in such a mill typically contains 250,000–450,000 particles larger than 6 mm, allowing correct representation of more than 90% of the charge in Discrete Element Method (DEM) simulations. Most AG/SAG mills use discharge grate slots which are 15 mm or more in width. The mass in each size fraction usually decreases rapidly below grate size.

Apr 24, 2014· Following implementation of these strategies, the SAG mill throughput when treating the harder copper/zinc ores increased from 2,750 tph to an average of 3,600 tph, and the optimization of the overall process improved energy efficiency, resulting in considerably less energy consumption per ton of …

Designed for discharge efficiency The role of the grate is to allow the discharge of the material ground in the mill via the slots. With our range of alloys and design experience we can offer the longest possible lifetime with the optimal grinding efficiency. The design of the grates will depend on: Drilling pattern Mill speed (rpm) Maximum grinding media diameter (mm) Grinding media filling ...

The number of impacts in primary ball mills are far more frequent but have less magnitude than those experienced in SAG mills. The increased frequency is due to the Increase in charge volume (35 – 40% versus 5 – 10%), higher mill speeds, and the larger number of balls per unit charge weight.

Converse~', some !,TJ'ate castings /CwtuJ'e peelling q( the edges during mill operatioll, thereby decreasing open area. al1d there/ore preventing (he desired top size product/i'om exiling the mill. SAG mill Ihroughplll requires grate holes to relllaill open or else Ihroughplll is restricled. ~)'

one SAG mill feeding two ball mills in a closed circuit with a hydrocyclone battery (Figure 1). The aim of the ball mill/ hydrocyclone circuit is to produce the optimum flotation feed particle size while maintaining grind throughput. The optimal operating point is a trade …

Similar to slurry flow-back, the pebbles flowing back into the mill increase with larger pebble port or grate slot size. As the pebbles flow down and slide across the grate slots, they get an equal chance to go back into the mill. Similar to slurry pool formation, pebbles flow-back would increase the quantity of critical size material in the mill.

Keywords: grate, SAG-Mill, DEM-Simulation, flow-back, carry-over 1. Introduction Size reduction of ores has an important role in the process of obtaining various metals. For example, for copper the ore must be separated from the mineral and must reach sizes smaller than 50 m, and this size reduction process takes place in successive stages and ...

and size distribution, water discharge rate, ball throughput, bearing pressure, pebble throughput, and toe and shoulder angles of the internal load. 2.1 SAG mill model The particles fed to the mill are ground in the milling chamber and subsequently downloaded into the discharge zone, where, according to a classification probability, they

Mar 14, 2007· Similar to slurry flow-back, the pebbles flowing back into the mill increase with larger pebble port or grate slot size. As the pebbles flow down and slide across the grate slots, they get an equal chance to go back into the mill. Similar to slurry pool formation, pebbles flow-back would increase the quantity of critical size material in the mill.

The load in such a mill typically contains 250,000–450,000 particles larger than 6 mm, allowing correct representation of more than 90% of the charge in Discrete Element Method (DEM) simulations. Most AG/SAG mills use discharge grate slots which are 15 mm or more in width. The mass in each size fraction usually decreases rapidly below grate size.

The effect of liner wear on SAG mill performance has gained much attention in recent years. It is commonly observed that the three key performance criteria of SAG milling; throughput, power and product size all improve as the liner wears. The increase in throughput is generally ascribed to the increase in the grate apertures and...

Many grates in operation are pegged by grinding media to varying degrees of severity. This paper introduces a comprehensive, accurate and rapid method to measure and track the size and pegging status of each and all grate holes in situ, and therefore provides tracking information on the Open Area of a SAG mill.

The mill product can either be finished size ready for processing, or an intermediate size ready for final grinding in a rod mill, ball mill or pebble mill. AG/SAG mills can accomplish the same size reduction work as two or three stages of crushing and screening, a rod mill, and some or all of the work of a ball mill. Because of the range of ...

The charge motion and breakage of particles inside the mill depends on the shell lifters design, while the discharge of ground particles is controlled by the grate and pulp lifters. The limitations imposed by poor grate and pulp lifter design become increasingly apparent with increasing size of ag/sag mills and their operation in closed circuit.

Jan 01, 2014· Therefore, as long as they are already finer than the SAG mill classifier slots and the SAG mill throughput is limited by the size reduction of the coarse, plus-grate size material, then passing some of them through the SAG mill one more time before sending them to the ball mills may not be such a bad idea. Download : Download full-size image ...