properties of ores include the Bond ball mill work index and the Bond rod mill work index.
. These are empirical indices determined by closed circuit grindability tests developed by
. in the mid 1930's. They require a specific 305mm diameter x 305mm long (inside dimensions)
.
Design engineers generally use Bond Work Index and Bond energy equation to estimate specific energy requirements for ball milling operations. Morrell has proposed different equations for the Work Index and specific energy, which are claimed to have a wider range of application. In this paper an attempt has been made to provide a comparison of these two approaches and bring out their ...
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The results showed that using the nonstandard mills (between 20 and 35 cm in diameter), the Bond´s model constants (α=; β=, and γ = ), are unable to predict the Work Index ...
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A copy of Fred C. Bond's Method of Crushing and Grinding for determination of the Bond Index is included with each mill. This Ball Mill can be used continuously or it can be used for any number of revolutions, according to the type of grind desired. The FC Bond ball Mill comes with table stand, motor, clutch, revolution counter, motor starter ...
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The work index equation for a ball mill test was generated by Fred Bond to empirically predict the operating work index of an industrial ball mill (8 ft dia by 8 ft effective grinding length ...
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Reference mineral (Granite) of known weight and work index ( Kwh /tone) was ground for 30 minutes at a particular speed and power consumed was determined from the power rating of the ball mill. An identical weight of Wasagu Manganese ore whose work index was to be determined was ground in the same ball mill under same condition as
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The Bond ball mill work index (Wi BM, or BWi) conducted from a feed size of approximately 2 mm to a product size on the order of 100 µm. The Bond rod mill work index (Wi RM, or RWi) conducted from a feed size of approximately 10 mm to a product size on the order of 1 mm. The Bond crushing (impact) work index (Wi C, CWi, LEIT or IWi) conducted ...
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Bond Ball Mill (BBM) Standard Test The procedures to carry out the Bond grindability tests in ball mills and rod mills are outlined in Sections and They are usually referred to as the standard tests, but it
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Key words: Comminution, Bond work index, Grinding, Crushing, Ball mills, Rod Mills. Theoretical efficiency In their book Process Engineering of Size Reduction Ball Milling, Austin, Klimpel and Luckie (1984) stated that, "We have tried throughout this book to avoid the use of the term grinding efficiency because the degree of conversion of
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The Bond Ball Mill Grindability Test (Bond, 1952, 1961) gives the Bond Ball Mill Work Index. This Index expresses the resistance of a material to ball milling; the higher the value of the Bond Ball Mill Work Index, the more difficult it is to grind the material using a ball mill. This Index is widely used in the mineral industry for:
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samples and perform the rod mill test on the samples blend. Bond Ball Mill (BBM) Standard Test The procedures to carry out the Bond grindability tests in ball mills and rod mills are outlined in They are usually referred to as the standard tests, but it must be highlighted that the procedures haven't been defined by ...
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MenéndezAguado 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 − mm using samples of gypsum, celestite, feldspar, clinker, limestone, fluorite, and copper slag.
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The Bond's standard ball mill is used to determine the work index value of differ ent samples. The Bond work index is defined as the kilowatthours per short ton required to break from infinite size to a product size of 80% passing 100 µm. If the breakage characteristics of a material remain constant over all size ranges, the calcul ated work ...
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However, Bond Work Indeces are related to the type of equipment to be used (rod mill, ball mill, SAG uses Drop Ball parameterKwhr/m3, so it is more complex than just specific energy consumption ...
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The Work Index (BWi) is calculated according to Fred Bond's Equation. Bond Work Index for Testing Procedure. Cleaning and Storing of Ball Mill Charge after the Bond Work Index Procedure is done: Add about 500 g of silica sand into the mill containing the ball charge. Seal the mill. Rotate for 20 revolutions to clean.
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It is a wellknown fact that the value of the Bond work index (wi) for a given ore varies along with the grinding size. In this study, a variability bysis is carried out with the Bond standard grindability tests on different critical metal ores (W, Ta), ranging from coarse grinding (rod mills) to fine grinding (ball mills). The relationship between wi and grinding size did not show a clear ...
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Average grinding work index (Wi) by type of mate rial, according to Bond (see table ): The work index (Wi) expresses the kWh required to reduce a short ton of material from theoretically infinite feed size to 80 % passing a square screen opening of 100 microns. The work index values apply to ball mills grinding wet in closed circuit.
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Similar to a Comparative Work Index, this test is an open circuit dry batch grindability test run in the standard Bond Ball Mill for a set time. It can be used at mesh sizes from 65 to 200 mesh (normally 100 mesh). The test requires calibration against the standard Bond Ball Mill Work Index test to estimate the Work Index.
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The Bond's BallMill Work Index is a measure of the resistance of the material to grinding in a ball mill. This Index is widely used in the industry for comparing the resistance of different materials to ball milling, for estimating the energy required for grinding and for ball mill scaleup.
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HGI vs Bond Index Test Bond Index HGI Mill Comparison Tube Ball mill Babcock mill (ringball) Target Particle Size Any size below 75µm Particle Size Range < (powder) or pellet size µm Mass constriction Volume 700ml Mass 50g Output kWh/ton HGI Index Suitable materials Any Good quality coals
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The ball mill work index laboratory test is conducted by grinding an ore sample prepared to passing mm to product size in the range of 45150 µm, thus determining the ball mill w i .
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µm. Note that—in order for no correction factor for ball mill product fineness to apply—the ball mill circuit P80 should be no less than approximately 70 µm (Bond, 1962). This Bond Efficiency determination should not be applied to circuits with a P80 finer than approximately 70 µm without making qualifications. 3.
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However, the ball diameters vary due to wear. Therefore, the total ball number should be adjusted from time to time to ensure a total mass of grams. The grinding jar of the Bond Index Ball Mill measures 12″ x 12″ and has wellrounded corners. Module Rod Mill. Minerals precrushed to < mm and sieved ; Drillcore precrushed to ...
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A modified equation has been proposed to calculate the Bond Ball Grinding Index (BWI), that considers the ratio of the MSL14K mill net grinding power to the net grinding power of Bond ball mill.
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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 ...
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For the ball mill grindability test, the work index is calculated from the following revised equation (in short tons): where: Pi = sieve size tested (microns) Gpb = ball mill grind ability Wi, P F have the same meanings as in the top equation. Equipment required: Laboratory ball mill, cm x cm with following ball charge: Agitator ...
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world. It shows that the ball mill work index is normally distributed with an average of and a median of kWh/t. bOnd rOd mill GrindAbility The Bond Rod Mill Grindability Test is performed similarly to the ball mill test. The feed sample is stagecrushed to ½" and the test is run under a circulating load. As in the ball mill ...
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The Bond work index, W i, is defined in a Bond ball mill on the samples of standard size − + 0 mm. In practice, it is possible to find materials of nonstandard size that are finer than mm.. In this work, a procedure for the calculation of the Bond work index is suggested for cases when the Bond grindability test is conducted on samples of nonstandard size.
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The ball mill grindability test is used for describing ore hardness and it is so widespread that the Bond Work Index generated from the test is often referred to as an ore characteristic. The ore resistance to grinding and energy consumption can be expressed using the work index and Bond's Third Theory.
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Once finished the grinding cycles, a minimum of five, the ball mill Bond's work index w i [kWh/sht] can be calculated using Equation (2). In order to express it in metric tons, the corresponding conversion factor must be used. wi = 100 p 10 P80 p F80 (2) where: w i is the ball mill Bond's work index [kWh/sht];
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The ball mill is designed to accept a ball charge in accordance with F. C Bond's standard. This ball charge consists of 286 balls as follows: 44 x 35mm balls; 67 x 30mm balls; 10 x balls, 71 x balls and; 94 x balls; Fully automated version of the Bond Index Ball Mill is also available on request.
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Conclusions. The power model and linear model both will give reasonable P80 estimates given the P100 of a Bond ball mill work index test product. The power model might be marginally more robust ...
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