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Solving Eq. (5.1b) for n=3/2 gives the same form as Eq. (5.4) with the constant 2 K ahead of the bracket. In effect the 2 K is replaced by (10×Wi), which is convenient because Wi becomes equal to W in the case of grinding from a theoretical infinite feed size to 80% passing 100 µm.The Bond model remains the most widely used, at least for the "conventional" comminution equipment …
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A mill is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting, In general, grinding processes require a relatively large amount of energy; for this reason, an experimental method to measure the, The power predictions for ball mills typically use the following form of the Bond equation:...
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Furthermore, because the energy required during crushing and milling increases as the inverse square root of the product size per the Bond equation ( Bond, 1961 ), the majority of the power during comminution is dedicated to the high energy milling operations used to produce feed for froth flotation operations and subsequent separation steps ...
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For overflow ball mills, the charge should not exceed 45% of the mill volume . For grate discharge mills, the charge should occupy about 50% of the mill volume . Bond developed a relationship that can be used to determine the percent charge by volume as a function of the vertical height above the charge, He, and the radius of the mill, R, i.e.,
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The Bond Ball Mill Work Indices of the blends tested were between . ... to Equation 1 (Wills and Napier-Munn, 200 6). In . Equation 1, W is the spec ific energy o r work done,
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SMC Data Processing. The results from conducting the SMC Test® are used to determine the drop-weight index (DWi) which is a measure of the strength of the rock as well as the comminution indices Mia, Mih and Mic. In conjunction with the Bond ball mill work index they can be used to accurately predict the overall specific energy requirements of ...
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Number of revolutions of the ball mill for the next run and percent circulating load were calculated. The grinding process was repeated until a target 250% ± 2% circulating load was obtained. Figure 1. Grinding Method III. Results and Discussion To determine the Bond work index of the given ore, equation 1 was used.
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Grinding Studies. Two kinds of mills, BBM and LBM, were used to achieve the desired P 80 passing percentage of 150 μm with an acceptable range of hematite liberation (> 75%) at optimum grinding time. The BBM is a standard ball mill having a length and diameter of 300 mm × 300 mm with smooth liner as shown in Fig. 2.A rotating drum is attached to a …
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The empirical formula to calculate Bond Mill Work Index (BWi) is presented in the equation (2) BWi = 44, 5 U 1 0, 23 G bh 0, 82 ( 10 U 80 - 10 F 80 ), ( 2 ) wherein U 1 is the passing size in micrometer of the test sieve, G bh is the ball mill grindability and U 80 and F 80 are passing values in a mount of 80% in the sieve ...
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The goal of this work is to create an equation to adjust a Bond ball mill work index from one P 80 basis to another. The proposed model consists of two components, the variable coefficient that is determined from a specific work index determination and a fixed exponent determined by a calibration procedure.
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grams per revolution (Gbp) is the ball mill grindability. The ball mill work index, Wi (kWh/short ton) is calculated from the following equation (Bond 1961):1 The mill should be cleaned by either blowing air into it or wiping the interior with a cloth and or brush. The FC Bond ball mill is now ready for the next sample.
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bond 3fs law for crushing mills. Relationships between comminution J energy and product. ball/rod mills and has become more likely a standard. The general form of Bond's equation is as follows: [6] where W is the work input (kWh/t); Wi is the work index (kWh/t) which expresses the resistance of the material to crushing and grinding; and F80 and P80 are the 80% passing size …
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Mill Ball Mill Closed circuit crushing to 16 mm Open circuit 8' dia. rod mill to 1 mm Closed circuit 8' dia. ball mill to P80 um The ore Test Work Index = Circuit Operating Work Index 9 The Standard Bond Circuit Coarse Ore Bins Fine Ore Bins Screen Crushing Screen Classification Rod Mill Ball Mill THIS IS THE REFERENCE BASIS FOR ALL WORK ...
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Menéndez-Aguado et al. examined the possibility of determining the work index in a Denver laboratory batch ball mill with the same inner diameter as the Bond ball standard mill. The research was performed on the size class of −3.35 mm using samples of gypsum, celestite, feldspar, clinker, limestone, fluorite, and copper slag.
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and a Bond laboratory ball work index test to have been carried out as the model requires the SMC Test ® parameters Mia, Mic, Mih, DWi and the ore specific gravity as well as the Bond ball mill work index (Wib). As the Mia, Mic, Mih, DWi and the ore specific gravity all come from the same SMC Test ® and are interrelated, any
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micrometers in size. According to the Bond standard procedure, the work index is determined by simulating a dry grinding in a closed circuit in the Bond ball mill to achieve 250% circulating load (Bond, 1949, 1952, 1961). The test is performed on a raw material approximately weighing 10 kg, which coarseness is -3.327 mm.
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Wet bond mill test 371 The ball mills operate at a pulp density of approximately 40% solids by volume (Wills, 1992). Wet bond mill test 373 REFERENCES Bond, F.C., Crushing grinding calculations Part I. British Chemical Engineering, 1961, 6(6), 378-385.
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theoretically infinite feed size to 80 passing 100μm (Wills and Napierpercent -Munn, 2006). Bond devised several methods for predicting ball-mill and rod-mill energy requirements and provided an accurate measure of ore grindability (Gupta and Yan, 2006). The standard Bond
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Bond Ball/Rod Mill Work Index. Bond ball mill work index (BBMWI) test is a standard test used to measure the ball mill work, which is calculated in accordance with the procedure proposed by the Bond [21]. The BBMWI determines how much energy is needed to grind a sample of ore in a ball mill [22].
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A Bond Ball Mill Work Index may also be used in the simulation and optimisation of existing mill(s) and the associated grinding circuit(s). Sample requirements: A minimum of 8 kg of material crushed to nominally minus 10 mm is preferred. JKTech would stage crush the sample to minus 3.35 mm, as required for the Bond Ball Mill Work Index test feed.
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Having estimated F80 and P80, the power required was expressed in terms of the Bond work index as (4.49) Power = W i Q 10 1 P 80 − 1 F 80 kW where Q = the capacity in t/h Wi = is the work index in kWh/t and P80 and F80 are in micrometres
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For P80s finer than 75 μm, the Levin test, a modified Bond ball mill work index test, may be used to predict grinding performance. Signature Plots. No general work index formula governing energy use over a range of conditions, like the Bond equation for intermediate grinding, has yet been found for the fine grinding regime.
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ball mill sizing with bond method work index base A comparison of the Bond method for sizing wet tumbling. · A comparison is made of the results from a ball mill model simulation with those of the conventional Bond ball mill design method, for a material whose breakage characteristics and Work Index have been determined.
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· Table 1 Bond mill charge distribution Ball diameter, inch No. of balls Distribution, % 1 ½ 25 8.8 1 ¼ 39 13.7 1 60 21.0 7/8 68 23.9 3/4 93 32.6 The standard Bond grindability test is a closed-cycle dry grinding and scree ning process, which is carried out …
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For the standard Bond equation, the 𝐶𝐹 𝑒𝑡 term is equal to 1, but the equation is only valid for the equipment that Bond used to derive the original equation: a closed-circuit, six-foot diameter wet ball mill operating with hydrocyclones and after a rod mill [4].
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Since for the ball mill design we are using 80% passing, the required value of C2 for the ball mill will be equal to1.20. C3 is the correction factor for mill diameter and is given as; 𝐶𝐶3 = 2.44 𝐷𝐷 0.2 (3) However, it is important to note that C3 =0.914 vessel used in …
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Bond's work index which is defined as the resistance of the material to grinding. The standard equation used by them for the ball mill work index (Bond work index) is as follows. / F 80 80 0.23 0.82 /10 44.5 1.1 GP W i bg i (4)
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Ball Mill Wio, BWio 8.6 Circuit Wio, OWio 14.6 Bond Ball Mill Work Index, BWi, kWh/t 13.4 Bond Rod Mill Work Index, RWi, kWh/t 18.1 Table 1. Example of AG/SAG Ball Mill Circuit Wio Calculations [1] [2] ABstrAct Optimum use of power in grinding, both in terms of grinding efficiency and use of installed capital, can have a large effect on ...
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The Bond Ball Mill Work index test, first developed by Fred Bond in 1952, is the industry standard for sizing mills and measures the resistance of an ore to grinding. The Work Index can be used to determine the power required for closed circuit ball milling.
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