Question: a ball mill is operating at an efficiency of 95% with a filling volume of maximum 1.52m 3. the ore has a Wi od 20 kW/ton. The RD of the crushing balls are 6.0. The charge volume is about 55% calculate what length and diameter of mill is (a) required to reduce ore size from 6mm to 200(um) (b) what will be the critical speed of the mill ...
Question 3 [25 marks) A ball mill is operating at an efficiency of 80% with a filling volume of maximum 1.32 m. The ore has a W. of 19 kW/on. The RD of the crushing balls are 5.0. The charge volume is about 45%. Calculate the following a) What length and diameter of mill is required to reduce ore sizes from 4 mm to 200 um?
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For any closed circuit ball mill system there is an optimum circulating load for maximum output and minimum kWh/t. Increasing circulating load is desirable as a means to …
Ball mill liner efficiency based on liner geometry and its influence on kW-hours/ton, total tons/life cycle, and P80 transfer to cyclones. Ball mill grind is based on different …
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Learn how to characterize the performance of ball mill circuits using the functional performance equation. This module covers the elements, calculations and applications …
A ball mill is operating at an efficiency of 80% with a filling volume of maximum 1.32 m3. The ore has a Wi of 19 kW/ton. The RD of the crushing balls are 5.0. The charge volume is about 45%. Calculate the following: a) What length and diameter of mill is required to reduce ore sizes from 4 mm to 200 um? b) What will be the critical speed of ...
The ball charge is a function of the bulk fraction of the SAG mill volume (Jb) occupied by balls; the ore retained in the mill is the result of the volumetric filling which depends on the ore size distribution (specially the % +6″ and the % −6″ +1″), on the rotational speed (N/Nc) and on the solid concentration by weight fraction inside ...
Ball mill shape factors in the period prior to 1927 (Taggart, 1927) averaged l.l/1 for 29 center discharge mills and 1.0/l ... with increasing feed rates critical filling is at or near 50% mill volume. Power drops rapidly when this level is ... Bougainville's 5.5 x 6.4 m mills, when drawing 3400 kW, capacity averaged 463 mtph at an average ...
Explain the role of ball mill in mineral industry and why it is extensively used. Describe different types of ball mill design. ... P M / M B = 10.14 kW/t; With ball density = 7.8 t/m 3. M B = 57.75 t; Slump correction factor check: D > 2.4 m but d > 45.7 mm, so no slump correction required;
This charge weight is usually calculated for the percent filling determined from the performance of the pilot plant tests and by the design of the feed end of the mill. ... Power drawn at the pinion is 448 kW, 13.617 kWh/tonne (SAG mill) and 570 kW, 17.325 kWh/tonne (ball mill) when processing 32.9 mtph, for a total of 30.942 kWh/tonne or …
Question: A ball mill is operating at an efficiency of 80% with a filling volume of maximum 1.32 m3. The ore has a Wi of 19 kW/ton. The RD of the crushing balls are 5.0. The charge volume is about 45%. Calculate the following:a) What length and diameter of mill is required to reduce ore sizes from 4 mm to 200 um
This tool calculates the percent ball mill filling degree from one of the methods below: 1) Using the effective mill diameter and free height above ball load. 2) Using the effective mill diameter, number of exposed and total lifter rows. To use: Enter the mill diameter inside the liners. Enter the free height above the ball load (method 1).
The design of different types of Tubular Ball Mills used for size reduction of crushed Run-of-Mine ores is described in some detail followed by descriptions and mathematical considerations of their operation. ... for operation the critical rotational speed, energy consumption for specific capacities of mills are described in some detail using ...
The 7.8 × 11.7 m (25.5 × 38.4 ft) primary ball mill was operating at 33 % filling, with a fresh feed solids rate of 1,150 t/h, 70 mm of make-up ball size, a power draw of 14,355 kW, and with a grate discharge. The secondary ball mill, with the same dimensions, was operating with 34 % filling, fresh feed solids rate of 1,150 t/h, make-up …
The charge filling in a ball mill is about 30–45% of the internal volume of the mill, about 40% of this being void space. As discussed in Section 7.2.2, the reason is the power draw passes through a maximum at about a filling of 45%. Given the cost of media it may be economic to operate at the lower end of the filling range, even at the ...
The ball mill filling can be estimated from the geometry of the ball charge at rest. However, in terms of the angle θ, ball filling (J B) may also be computed as …
• Jx is the mill filling of component x, as a fraction of total mill volume (e.g. 0.3 for 30%) • L is the mill effective grinding length, m • P is the power evolved at the mill shell, kW
Figure 16 shows that wear is dependant on the ball mill filling percentage. The wear rate increases with increasing ball mill filling percentage. Interestingly, the ratio of total wear rates to mill filling percentage indicates that the per unit percentage of ball charge volume decreases with increasing ball charge volume (Table 5). 6.
Mill power draw is about 9500 kW at 30% mill filling; mill full length L = 9.6 m; mill diameter D = 7.312 m inside liners; mill speed ϕ c = 75% of critical; ball filling J ranging from 25% to 33%; steel ball diameter d = 40 mm. The mill is lined with 44 rubber lifters which have a height of 100 mm.
A) Total Apparent Volumetric Charge Filling – including balls and excess slurry on top of the ball charge, plus the interstitial voids in between the balls – expressed as a percentage of the net internal mill volume (inside liners). B) Overflow Discharge Mills operating at low ball fillings – slurry may accumulate on top of ... Ball Mill …
A pilot-scale grinding technology of ceramic medium stirred mill was proposed in this study. Based on the specific productivity and grinding efficiency, the appropriate grinding parameters were ascertained as follows: material ball ratio of 0.7, ceramic ball medium size ratio (10 mm: 15 mm: 20 mm = 3:2:5), stirring speed of 110 …
where m p is in kW; D is internal mill diameter (meters), L is internal mill length (meters); J is total fractional charge loading of the mill; J B is the fractional mill filling by balls; ε B is the effective porosity of the charge, taken as 0.3; ρ s and ρ b are true densities of rock and balls (tons per cubic meter), respectively; w c is the weight fraction …
For values of (D/d) appreciably less than 20, however, the value of the function is not independent of the filling of the mill. In order to test the effects of variation of the coefficient of friction tests have been carried out in which: The balls and mill are cleaned and tested dry. The balls and mill are cleaned and slightly oiled.
such as mill filling, ball load, and the percentage solids of the mill slurry content (Napier-Munn et al. 1996). Changes in the feed size distribution
12.5′ x 20′ Morgardshammar Ball Mill, 1400 KW Motor, 50 Hz, Rubber Liners, Mill Speed 16 RPM. Equip yourself with the gold standard. Manufacture & Design. ... Charge Weight: 116 Tons (40% fill) Mill …
High temperature of the ball mill will affact the efficiency 3 For every 1% increase in moisture, the output of the ball mill will be reduced by 8% -10%. 4 when the moisture is greater than 5%, the ball mill will be unable to perform the grinding operation. 5. The bearing of the ball mill is overheated and the motor is overloaded Reasons
Ball mills are available with a grinding drum made of porcelain (100-250 litres) or steel, with a lining of steatite or aluminium oxide (40-12,000 litres). The ball mills are also equipped with a fully integrated or remote-control system. KERA experts can also revise the ball mills and replace the ceramic lining.
• P is the power evolved at the mill shell, kW • PN is an empirical "power number" which varies with mill filling and speed, unitless • ρCharge is the density of the mill charge as given in Equation 3, t/m³ Ball charge is not explicitly used in the power formula, but is considered in the mill charge density formula: %(1 234 567ˆˆ ...
Charge Weight/Volume/Percent Filling. Ore Specific Gravity. Percent Rock or Ore Charge. Percent Ball Charge (if semi-autogenous). Percent Solids – in the mill. ... 3650 mm semi-autogenous mill driven by a 3954 kW variable speed dc motor, and one 5030 mm diameter x 8340 mm secondary ball mill driven by a 3730 kW synchronous motor. Four …
The effect of ball load composition, by varying the grinding media size distribution (e.g. alternatively by mixing four groups of 19.5, 38 mm; 19.5, 50 mm; 38, 50 mm and 19.5, 38, 50 mm), on the ...
Do you need a quick estimation of a ball mill's capacity or a simple method to estimate how much can a ball mill of a given size (diameter/lenght) grind for tonnage a product P80 size? Use these 2 …
The ball mill design given as: Diameter inside shell: 18 ft; Length (assumed to be flange-to-flange length): 29 ft; ... DCS Power, kW Mill filling Morrell Model, kW model, kW no density correction model, kW density …
How to do Ball Mill Parameter Selection and Calculation from Power, Rotate Speed, Steel Ball quantity, filling rate, etc. read more...
Lameck's work indicated that: Higher torque (power draw) can be achieved with increased packing efficiency – particularly for worn ball media. At lower mill speeds, the cylpebs …
Where K ωb (kW) was the power consumption of per ton of ball medium; D (D = 4.916 m) represented the effective volume of ball mill; The φ (%) was the space-filling factor; ψ (ψ = 75%) represented the rotation rate of ball mill; S S (kW) was the reduction of power per ton ball medium due to the ball diameter effect.
where k is the ratio of radii of internal and external layers of balls and ~0 is the filling of the mill with balls. The curves drawn up on the basis of this formula for the relationship :C L = f (n) for different ... motor on the mill (150 kW); 15. asynchronous electric motor (4.0 kW, 1500 rpm). To obtain the maximum output the optimum ...
Description. This article describes the Hilden and Powell (2018) approach for estimating the power draw of a tumbling mill.. Hilden and Powell extended Morrell's (1996, 2016) approaches to include the following features:Partial filling of the charge void space with slurry in two directions, from the charge shoulder towards the toe and from the outer …
CALCULATED VALUE OF DF, % Maximum ball size (MBS) Please Enter / Step-to Input Values Mill Feed Material Size F, mm