14.6 and a median of 14.8 kWh/t. bOnd rOd mill GrindAbility The Bond Rod Mill Grindability Test is performed similarly to the ball mill test. The feed sample is stage-crushed to ½" and the test is run under a circulating load. As in the ball mill test, the test can also be closed with various sieve sizes, but for AG/SAGWeb
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W = power consumption expressed in kWh/short to (HPhr/short ton = 1.34 kWh/short ton) Wi = work index, which is a factor relative to the kwh/short ton required to reduce a given material from theoretically infinite size to 80% passing 100 microns P = …Web
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Over the years, alternative procedures to the Bond grindability test have been proposed aiming to avoid the need for the standard mill or to reduce and simplify the grinding procedure. Some of them use the standard mill, while others are based on a non-standard mill or computation techniques. Therefore, papers targeting to propose a better …Web
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With the models proposed for α, β, and γ, the Bond Work Index (kWh/t) can be rapidly estimated (less than 2 hours) and show a high accuracy for mills of non-standard dimensions (R2
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The ball mill grindability test at 65 mesh showed 12 kWh/t. The internal diameter of the ball mill was 5.03 m and the length-to-diameter ratio was 0.77. The steel balls occupied 18% of the mill. The total load occupied 45% of the mill volume. If the mill operated at 72% of the critical speed, determine:Web
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= 1.12 kWh/t when expressed in terms of the crusher feed rate ... Ball mills in HPGR-Ball mill circuits tend to have more installed capacity than their counterparts in AG/SAG-Ball mill circuits.Web
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SAG mill compared to crusher and ball mill product size distributions (Powell et al 2014) ... SAG mill Specific energy kWh/t 7. 9 6.8 2.6 9.0 6.53. SAG mill volumetric filling % 16.1 26.6 30.6 32. ...Web
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A metric often encountered in the hard rock business is a measure of the power consumed per unit of desired product e.g. kWh/t of -75 micron material in cyclone overflow (assumes you want to grind to 75 microns). You have to compare the specific electrical energy consumption required for the targeted milling final product particles size.Web
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the ball mill has reached 5–6 m, and the unit output can reach more than 300 t/h. The unit ... the electricity consumption of the mill is 15 kWh/t, and the system electricity consumption.Web
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The Bond work index, W i, is defined in a Bond ball mill on the samples of standard size ... W = 1.1 44.5 P c 0. 23 G 0.82 10 P − 10 F, kWh t where: P c is the aperture of the comparative screen (μm), G is the net mass of the newly screened undersize produced per mill revolution (g) ...Web
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The stirred mill was observed to produce finer products with less energy consumption than the ball mill. It was found that the P 80 of 235.5 µm achieved with an expense of 32.45 kWh/t energy consumption in the stirred mill. In the ball mill case, P 80 of 275.4 µm product was obtained with an energy consumption of 54.67 kWh/t. It may be …Web
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It was found that the ball mill consumed 54.67 kWh/t energy to reduce the F 80 feed size of 722.2 µm to P 80 product size of 275.4 µm while stirred mill consumed …Web
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The feed samples of X, Y, and Z iron ores were ground in the BBM (ball mill refers to a BBM of size 300 mm × 300 mm with smooth liners) to identify the PSD, BWI, and RT of each ore. Grinding experiments were conducted according to Bond's standard test procedure [].For each iron ore sample, the RT taken to produce 250% circulating load in …Web
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mill specific motor output power (kWh/t) W i. Bond ball mill work index (kWh/t) P 80. sieve size passing 80% of the mill product (μm) F 80. sieve size passing 80% of the mill feed (μm) The "efficiency factors" (Rowland, 1975) modify Eq. (1) so that it caters for circuit conditions which are different from that Bond used to develop his ...Web
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A survey was conducted at the Tropicana mine to compare the performance of the HPGR and ball mills with the design. The ore competence was similar to the …Web
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The measured BW i was 14.0 and 6.6 kWh/t for the medium/hard and soft ore, respectively, at a closing screen size of 106 μm compared with the simulated values of 13.2 and 5.6 kWh/t. The ability to simulate the Bond work index test also allows examination of truncated ball mill feed size distributions on the work index.Web
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Metallurgical tests indicated an average Bond ball mill work index of 14.8 kWh/t for Main Zone material, with a range of 11.5 to 16.6 kWh/t (Imperial Metals, 2012). DESCRIPTION OF THE SAG AND BALL MILL CIRCUITS A conventional SAG and ball mill circuit (SABC) is used to treat material at a production rate of 30,000 t/d. TheWeb
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The second challenge after getting the correct kWh/t for the SAG and ball mill on a suite of variable hardness samples is to decide whether the design will be for fixed tonnage or variable tonnage. The effect of variable tonnage on recovery must be unknown because no one seems to be interested in this effect even in copper flotation plants ...Web
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(kWh/t) and WioACTis the Actual Operating Bond Work Index (kWh/t). • If the Wi Efficiency Ratio is 1.0 or , the circuit is per-forming with the same efficiency as the Bond Standard Circuit (and the ore Wi = circuit operating Wi), in accor-dance with the correlation that Bond (1962) established between plant operating data and test data ...Web
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The results demonstrated that the VRM unit consumes around 81% (9.75 kWh/t of raw materials), and 36% (5.8 kWh/t of raw materials) more energy to grind raw material than the IBAT unit and domestic ...Web
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An alternative mill ball charge is proposed that closely approximates Bond's original total ball mass, number of balls and ball surface area. Results of 30 Bond Work index tests of six pure materials (calcite, magnesite, labradorite (feldspar), quartz, andalusite and glass) using closing screen apertures (P 1 ) values of 500, 250, 125, 90 and ...Web
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3.3 Ball Mill Design The ball mill designs also follow the Bond/Rowlings method with comparison with other methods. Again the method of use is the same 3.4 SAG/BM Combined design This is the combined model of the SAG and BM models. The difference is that a provision in the BM model allows for the fact that finished product is in the BM feed.Web
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Specific energy consumption (kWh/t) HPGR-ball mill: 14.7: 20.0: VRM: 19.6: 27.5: Horomill: 14.4: 17.5: Ball mill: 14.4: 32.5: The results show that high compression grinding mill circuits are more energy efficient than conventional single stage multi-chamber ball mill circuits. The circulating load ratio around the circuit is much higher ...Web
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The specific energy value (7.4 kWh/t) obtained of both SAG-5 and SAG-6 tests were interpreted as equivalent to an increased ball charge and mill rotating speed. Both changes were thus beneficial to the SAG mill performance compared with the SAG-2 test performance (7.8 kWh/t), where both ball charge and mill speed were relatively low.Web
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Every year several billion tons of metallic ores, cement, min- erals, and numerous other solids used in the ceramic and chemical industries are subjected to …Web
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The crushing-ball milling circuit specific energy was estimated on the basis of the Bond equation and the relevant Bond work indices (Table 4), with the crushing energy given from the SAG/AG F80 to a nominal product with P80 of 8.0 mm being added to the ball mill energy from F80 of 8.0 mm to the actual P80 of the pilot test, given either by the ...Web
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E SAG = SAG mill pinion energy (kWh/t) M = mass of mill ore charge (4.5 litres) This equation estimates the pinion energy to grind from a feed size, in the full size …Web
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A new methodology to obtain a corrected Bond ball mill work index valid with non-standard feed size. ... W i – Bond ball mill work index (kWh/t, metric tonne basis). The standard Bond ball mill test requires a material of appropriate granulometric composition, −3.35 mm created by a stage-crushing process, which is ground in a ball mill ...Web
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Circuit Bond work index (kWh/t) Specific energy consumption (kWh/t) HPGR-ball mill 14.7 20.0 VRM 19.6 27.5 Horomill 14.4 17.5 Ball mill 14.4 32.5 The results show that high compression grinding mill circuits are more energy efficient than conven- tional single stage multi-chamber ball mill circuits.Web
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The mill was expected to produce a product of 80% passing 150 microns. The feed rate to the mill was 300 t/h. The ball mill grindability test at 65 mesh showed 12 kWh/t. The internal diameter of the ball mill was 5.03 m and the length to diameter ratio 0.77. The steel balls occupied 18 % of the mill. The total load occupied 45% of the mill volume.Web
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Measurement of electrical energy consumption in a Bond ball mill Authors: Mike Daniel cmd consulting Abstract and Figures In this paper a new digital energy meter is being evaluated as a...Web
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related to the required circulating load around the ball mill. Therefore, if the power consumption of the ancillary equipment such as conveyors is not considered, wet grinding circuits may be at a significant ... kWh/t.km 0.76 0.69 0.49 0.45 0.21 0.36 0.36 0.33 0.64 0.72 A similarly simple relationship was required to approximate the energy ...Web
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A Bond ball mill work index is then performed on the mill product for the design of SAG-ball mill circuits. This is important because it was found that there was a 1–1.5 kWh/t higher ball mill work index if the –3.35 mm ball mill test feed size is obtained by SAG mill grinding compared with crushing.Web
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Comparative comminution efficiencies of rotary, stirred and vibrating ball-mills for the production of ultrafine biomass powders. April 2021; Energy 227(3):120508; ... more than 9000 kWh.tWeb
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As shown in this figure, the rotational speed of the mill has a major influence, with nearly 40% of energy saving when this operating condition is varied, from 13.3 kWh/t to 8 kWh/t, while the rotational speed is reduced from 80% to 50% of the Vc . The same pattern is observed when the media charge is varied, from 10.6 kWh/t to 7.8 kWh/t, …Web
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1. Rod-Ball Mill Circuit (Single-Stage Ball Mill, Multi-Stage Ball Mill, or High Pressure Grinding Roll-Ball Mill) 8.56 WioACT= ––––––––––––––––––––= 11.8 kWh/t 10 10 …Web
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