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Motor torque, load torque and selection of motors 2/45 Performance In such motors the pullout torque is normally less than the starting torque. This is because the pullout torques by the two cages occur at different speeds. Such motors would possess a low power factor and efficiency compared to an ordinary squirrel cage motor, because of the high
Motor load factors in many facilities are more in the range of 40% 50%, than in the range of 80% that had been a standard assumption for many years of doing audits. Rarely do you find a motor running at load factor. However, not all motors at a facility are running at the same load factors.
SAG mill (4% ball charge, 90% Nc) A cross between AG and SAG for average competency, abrasive ores. Typically operated in RSA on Witwatersrand Gold Ore Driefontein (Underground), Kloof, Jacobina 6 SAG mill with recycle crusher (8 – 15% ball charge) Competent ores, better suited to coarse grind sizes. High aspect mills are recommended to ...
Most electric motors are designed to run at 50 to 100 percent of rated load. Optimum efficiency is at 75 percent of rated load. Thus, a 10 horse power (hp) motor has an acceptable load range of 5 to 10 hp; peak effi ciency is at hp (see Figure 1).
Sep 22, 2014· Failure analysis of ball mill gears, SAG 2001 Conference, Vancouver. [2] Fresko et. al. 2004. The use of finite element analysis in the understanding of alignment and load distribution in large grinding mill gear and pinion sets. SME Annual Meeting, Denver, CO.
Ball Mill Recirculating Load 27 SAG Mill Load Control 28 Mill Power Indication 28 Cyclone Pressure 28 SAG Mill Speed Control 28 Pebble Crusher – Steel Removal Logic 28 Sound Pattern Indication 28 Supervisory Control 29 High Level Control 29 GRINDING MILLS 30 Calculating Motor Mill .
LG A mill power equation for SAG mills. Minerals and Metallurgical Processing. Feb 1990 pp5762. Gross power No load power Net power drawn by the charge () The net power is calculated from Net power e! c./ Watts () In equation, D is the diameter inside the mill liners and Le is the effective length of the mill including the ...
Typical motor speeds are either 4 or 6 pole, 1750 rpm or 1170 rpm for 60 Hz ... service factors due to the increased number of load cycles. See table 5 for recommended service factor values. These service factors would multiply ... Normally service factors are, or greater. Mill .
3 Factors Affecting Sag Characteristics 1. Type of fault: Type of fault in the power system is the first factor which affects sag characteristic. Depending whether the fault type is balanced or unbalanced, sag will be balanced or unbalanced in all three phases. The magnitude and phase angle of sag will also depend on the type of fault [2]. 2.
Usually, the charge volume of SAG mills occupies between 30 and 40% of its internal volume at which the grinding rate is maximised. When the charge volume is more, then the throughput suffers. The fill level is monitored by mounting the mills on load cells. Presently, most modern mills are invariably equipped with such an arrangement.
the average torque required is reduced to , allowing less than 175% starting current. The choice of a wound rotor motor requires the use of power factor correction capacitors to meet the power factor requirements of the electrical utility. The cost of these capacitors needs to be included in the analysis of mill motor
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
B: Sine of angle of incline C: Center to center distance (inches) D: Diameter of drive pulley (inches) d: Diameter of tail pulley (inches) E: Effective tension (lbs.) E1: Slack side tension (lbs.) E2: Tight side tension (lbs.) F: Coefficient of friction (See Table #1) G1: Load per square ft. (lbs.) G2: Load per hour (lbs.) HP: Horsepower K: Drive Factorsee table #2
where T b is the belt tension (N), f is the coefficient of friction, L is the conveyer length in meter divided by two, g is the acceleration due to gravity ( m/s 2), m i is the load of idlers within 1 m length of conveyer belt (kg), m b is the load of 1 m length conveyer belt (kg), m m is the load of the conveyed materials per meter length ...
surface of the mill flange. Typically, the synchronous motors used in SAG mills have a power higher than 10 MW. Even ball mills have a power larger than 10 MW. For this reason, they have an important impact in energy consumption and in the operation of the power distribution system. Figure 1. Picture of a typical GMD system for a SAG mill
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.
Once the basic operating conditions have been defined for the mill designer then, and only then, can he begin taking into account shell and head stresses and trunnion bearing sizes required to carry the load and to give the required openings for feeding and discharging the mills. Mill heads are key structural components of any grinding mill. They must carry the load of the shell assembly ...
This paper describes the detail design of a typical Autogenous mill. Discover the world''s research. 17+ million members; ... Load factor for surface durability ... centrifugal pump / motor, water ...
Typical Load Factor For Sag Mill Motor Choosing a SAG Mill to Achieve Design Performance Starkey... To summarize this procedure a typical suite of laboratory data is presented below to... It is the consultant''s job to assess these factors and methods and.... 15% steel in the SAG mill and a load of about 35% and represents the motor power...
Typical semiautogenous (SAG) mills throughput and toe and shoulder angles of the internal load. 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 the internal charge of the mill
Table 4A Hooded Electric Appliance Usage Factors, Radiation Factors, and Load Factors Appliance Usage Factor F U Radiation Factor F R Load Factor F L = F UF R Elec/Steam Griddle Fryer Convection oven Charbroiler Opentop range without oven Hottop range without oven ...
5 Low ball charge SAG mill, high mill speed. (4% ball charge, 90% Nc) A cross between AG and SAG for competent, abrasive ores. As typically operated in RSA. 6 SAG mill (configurations 3, and 5 ) with recycle crusher Competent ores, better suited to coarse grind sizes as circulating loads can be high 7 SAG mills treating partially or fully
SAG, ball and cement mill chives, etc Experience to exceed your demands ABB has experience in cycloconvetter chives, having delivered about one third of the world''s cycloconverter power. ABB cycloconvelters were used in 1969 for ring motor drives on cement mills and later also with marine propulsion, mine hoist and It)lling mill main drives.
SAG mill control fundamentally means managing the load in the mill by adjusting the feed rate of ore to the mill and/or manipulating the rotational speed of the mill. The best way to measure load is to mount the mill on load cells. The load cells are calibrated to measure the total weight of water, grinding media (balls) and ore in the mill ...
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