It is clear that the effect of pebble removal depends on the amount of pebbles taken out of the SAG mill and that this amount depends on how many pebble ports are opened in the discharge grates. The best result is achieved by maximizing the number of pebble ports which at the same time maximizes the pebble flow rate.
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The resultant model explicitly described the effects of the mill discharge mechanism ( grate or overflow), as well as the shape of the end sections ( planar or conical).
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It embodies the peripheral discharge with grates, large forgedsteel balls, and the principal features of the modern ball mill. The results approach presentday practice, the chief differences being that the mechanical construction has been improved in the modern types. ... The screen analyses plotted in Fig. 2 show the effect of varying ...
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A generalized SAG mill power draw equation developed by Austin, is given by: where the parameters used in the model are defined as: mp= net mill power (kW) K = a constant (kW/ton ) D = mill internal diameter (m) L = mill length (m) J = fractional volume of mill filled by total charge. εB = effective porosity of the total charge.
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Grates form the outer DE millside lining. Most large mills have adopted cantilever grates,, grates where the center portion sits on the pulplifter channel wall and the sides are essentially unsupported (see Figs. 7 and 8). This grate type can provide a large opengrate area by using intergrate gaps.
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In a SAG mill the dimensions of the mill were m × m and the specific gravities of the mineral and that of the balls charged were and respectively.. The mill was rotated at 75% of its critical speed when 8 % of the mill volume was charged with grinding :1. The mill power drawn, 2. The maximum mill filling possible.
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Coarse particle flow through the grate of a dry SAG mill into the pulp chamber was simulated by Cleary (2004 wet mill applications a combined SPHDEM method was proposed by Cleary et al. (2006a ...
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Mill Liner Design Read online for free. ... (or at least to specify the design) parameters of the discharge end such as: Grate open area. Slot size. ... Recognize that other "nonmill" circuit equipment such .as pumps and flotation cells can have a direct effect on mill liner life. 4. Analyze the foundry source and ...
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Grate parameters include size of grate apertures and pebble ports, and open area fraction of grate and pebble ports. The fine size parameter comes from the SAG mill model fitting. Discharge functions used in simulations are presented in Fig. 15. No interactions between the mill discharge and the liner profile are considered.
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It has been widely accepted to go for grate discharge ball milling when a coarse product is preferred or to avoid production of extreme fines, but overflow discharge mills are preferred for their simplicity of design and production of finer product.
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Slurry discharge capacity of autogenous and semiautogenous mills and the effect of grate design ... A laboratory based study of tumbling mills has been undertaken in which the mill speed, grate open area and the position of the apertures were systematically varied and their effect on the relationship between water flowrate and holdup measured ...
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Grate Discharge Ball Mills have shown 25% to 45% more tonnage ground and a substantial reduction in power consumed per ton of material compared size for size with overflow mills. To illustrate the characteristics of various type mills we have shown the types of discharge for rod mills and ball mills.
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ball mills has an even larger effect on SAG mill capacity. ... (not appreciated), slurry viscosity, discharge grate ... so relative discharge area per mill capacity decrease s and transport time .
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Current AG and SAG mill circuits have continued the trend to larger, fewer mills. These large mills place a significant additional load on the discharge systems and it has become imperative that ...
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Discharge grates play an important role in determining the performance of autogenous, semiautogenous and grate discharge ball mills. The flow capacity (grinding capacity) of these mills is...
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The Discharge End (DE) pulp lifter is a critical component of autogenous (AG) and semiautogenous (SAG) grinding mills, having a significant impact on the throughput, efficiency and performance of mills. Underestimating the importance of an optimised liner design in a mill can lead to backflow and carryover processes which can ultimately ...
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Inadequate discharge of slurry by the pulp lifters is often a problem for single stage AG or SAG mills because of high circulating loads when operated in closed circuit with a fine classifier.
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Citic SMCC's slurry flow model for AG/SAG mills (grate discharge mills) was constructed using the approach originally adopted by Morrell and Stephenson (1996) who related the volume of slurry heldup in the mill to its rate of flow out of the grates. Morrell and Stephenson incorporated the effects of grate design, mill speed and charge volume.
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The amount of pebbles passing through the grate increases with the angle of the grate. It is imperative to ensure the efficient removal of both slurry and coarse pebbles (critical size) in order to ensure the efficient operation of AG/SAG mills. Elimination of the above mentioned material transport problems will allow the mill to respond truly ...
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Pulp lifters, also known, as pan lifters are an integral part of the majority of autogenous (AG), semiautogenous (SAG) and grate discharge ball mills. The performance of the pulp lifters in ...
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PTFI uses by (12 by 24 ft) vibrating screens to classify SAG discharge, employing two on the (34 ft) SAG mill circuit, and three on the (38 ft) SAG circuit. As most SAG circuits are now designed for the inclusion or subsequent addition of a pebblecrushing circuit, a design that incorporates screens allows maximum future ...
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Mill Type Overview. Three types of mill design are common. The Overflow Discharge mill is best suited for fine grinding to 75 106 microns.; The Diaphram or Grate Discharge mill keeps coarse particles within the mill for additional grinding and typically used for grinds to 150 250 microns.; The CenterPeriphery Discharge mill has feed reporting from both ends and the product discharges ...
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Morrell, S., Stephenson, I., 1996, "Slurry discharge capacity of autogenous and semiautogenous mills and the effect of grate design", Pebble porting a mill dramatically increases its discharge requirements, International Journal of Mineral Processing, Vol. 46, pp 53 72. and it has been shown that a large porting open area has an adverse ...
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Nation Reduces energy consumption by as much as 1520% in SAG Mills. Reduces equipment wear. Reduces operation costs. Researchers will seek to use computer modeling, especially process modeling of SAG mills, as an online tool to process ore more efficiently.
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1. Introduction The degree to which slurry is held up within autogenous (ag) and semiautogenous (sag) mills influences their grinding capacity and power draw. The roles of the grate and the pan lifters (in trunnion discharge mills) are particularly influential in this regard.
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A model for the effect of flowrate and viscosity of slurry on the holdup of slurry in a gratedischarge grinding mill has been developed. Given detailed specifications of the grate design (such as the area in the grate within which the holes are situated, the number of holes per m 2 and the hole size) and the flowrate and viscosity of the slurry flowing through the mill, the model provides ...
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Discharge grates play an important role in determining the performance of autogenous, semiautogenous and grate discharge ball mills. The flow capacity (grinding capacity) of these mills is strongly influenced by the discharge grate designopen area and position of apertures, as well as the performance of the pulp lifters.
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The current discharge model is under review, but the implications of this simplification appear to be small given the validation presented later in this paper. However, the most recent advances in slurry transport research (Latchireddi, 2002) will be implemented to account for the effects of grate design, mill speed, charge volume and pulp lifters.
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Product Size: All passing 6 mesh with 80% passing 20 mesh. Net power from pilot plant: KWH/ST. Mill, gear and pinion friction multiplier: Mill Power required at pinionshaft = (240 x x ) ÷ = 5440 Hp. Speed reducer efficiency: 98%. 5440 Hp ÷ = 5550 HP (required minimum motor output power).
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Figure 2 Crash stop of SAG mill showing pooling The mill grate discharge included square pebble ports which had very 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 cm ( inch ...
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A material supplier from Belgium would like to produce limestone powder for his custome...
India is rich in various mineral resources and it is an important mineral processing market
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