You need a twostage solution, first stage opencircuit mill and then second stage closedcircuit mill. First stage, will be broken into two parts as well, you use a Bond rod mill work index for the coarse component of the ore (+ mm) and the Bond ball mill work index for the fine component ( mm).
Ball Mill Work Index tests using crushed feed, and Standard Autogenous Grinding Design (SAGDesign) Tests, patented by Outokumpu. (See reference 8 below). The comparison of these results gives context to how the various measurements relate to each other and how they can be used to obtain an accurate design for the grinding mills required for
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 ...
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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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.
The Work Index is used when determining the size of the mill and grinding power required to produce the required ore throughput in a ball mill. 2. Procedure Bond Ball Mill Grindability The sample was crushed to passing 6 mesh (), from this a 700 cc volume was measured and weighed to be used as feed for the Bond Mill.
The Bond work index most commonly referred to is the BBM work index. This value is obtained in a 12" 12" laboratory mill running at 70 rpm, with rounded inner edges and without lifters. The grinding charge is comprised of a distribution of steel balls with several diameters. Table1shows the original Bond proposal [13], while the last Bond
The work index can either be measured in the laboratory (the Bond ball mill work index determination is a common example) or it can be calculated from the operating performance of a milling ...
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 mm, as required for the Bond Ball Mill Work Index test feed.
A wet grinding ball mill in closed circuit is to be fed 100 TPH of a material with a work index of 15 and a size distribution of 80% passing ¼ inch (6350 microns). The required product size distribution is to be 80% passing 100 mesh (149 microns). In order to determine the power requirement, the steps are as follows: Example Calculation
Use this online formula to calculate a Ball Mill, Rod Mill or SAG Mill Operating Work Index. Based on Fred Bond's work you can estimate the energy used into your grinding circuit. This is the most accurate and informative method, but much of the data necessary for its application is not yet available.
Abstract The Frederick C. Bond has several grinding indices (ball, rod, abrasion), one of which has been a significant guide for ball mills. The Bond ball mill work index is an expression of the material's resistance to ground and a measure of the grinding efficiency.
The Bond ball mill work index test is thought to be additive because of its units of energy; nevertheless, experimental blending results show a nonadditive behavior. The SPI(R) value is known not to be an additive parameter, however errors introduced by block kriging are not thought to be significant .
The P 80 of a ball mill work index test can be estimated if the P 100 is know based on this equation: Estimate grams per revolution when only P100 is known. NI43101 reports often provide P 100 and the work index. To estimate the other parameters, you can assume: the P 80 is × (P 100, µm)
Wi Bond Work Index Ws Specific energy correction for size distribution (kWh/t) WiBM Bond Ball Mill Test Work Index (kWh/t) 3. KEYWORDS Autogenous Grinding (AG), Ball mill, Bond Work Index (Wi), Comminution circuit, High Pressure Grinding Rolls (HPGRs), Rod mill, SemiAutogenous Grinding (SAG), Specific energy (W) 4. INTRODUCTION AND BACKGROUND
C) for coarse rocks (7550 mm), a rod mill work index (Wi RM) for intermediate sized particles (253 mm), and a ball mill work index (Wi BM) for small particles (<3 mm) (Ammtec, 2000). Laboratory testwork is required to determine these Work Indices, and each test requires carefully collected samples of rock that is representative of future mill ...
The work index Wi was defined by F. Bond as the specific energy (kWh/ton) required to reduce a particulate material from infinite grain size to 100 microns. ... The energy consumed by the ball ...
The Bond Ball Mill Work Index (Wi) is one such spatial estimate which remains difficult to infer correctly. The Wi defines the specific energy (kWh/ton) required in grinding a ton of ore in the ball mill from a very large size (infinite) to 100 m (Lynch et al. Citation 2015). At the time of writing, this variable is of particular interest for ...
Typical Mill Circuit Represented by the Bond Ball Mill Test. The procedure for the work index test bases the BW i value on the calculation of new fines generated in the test. This means that the fraction of fines in the feed should not influence the test result significantly, if at all.
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.
Istilah BWI sendiri dapat disebut lagi menjadi Bond Ball Mill Work Index (BBWI) atau Bond Rod Mill Work Index (BRWI). Ini tergantung dari media gerus yang digunakan selama percobaan, apakah bola baja atau batang baja. Untuk menghitung BWI digunakan formula sbb: Dimana. Wi = Nilai bond work index yang dicari (kwh/ton)
W is the work index measured in a laboratory ball mill (kilowatthours per metric or short ton) P 80 is the mill circuit product size in micrometers; F 80 is the mill circuit feed size in micrometers. Buhrstone mill. Another type of fine grinder commonly used is the French buhrstone mill, which is similar to oldfashioned flour mills.
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 ...
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 ...
The Bond Ball Mill Work Index (BBWi) test is carried out in a standardised ball mill with a predefined media and ore charge. The Work Index calculated from the testing can be used in the design and analysis of ball mill circuits. The test requires a minimum of 10kg of sample that has been stagecrushed to passing size of < mm.
Work index is the relation between the SEC and the amount of breakage in an ore. The most common form of this relationship is given as Equation 1, and is often referred to as "Bond's equation" or "Bond's law." E=10× √P − √ F 80 80 ) ( 1 ) Where: E is the specific energy consumption in kWh/t
This was displayed by a reduction in Bond ball mill work index (BBMWI) of the ore from to kWh/t after calcination. ... The ball mill had 12 grinding balls (each grinding ball had mm ...
A Bond Work index mill ball charge and closing screen product size distributions for grinding crystalline grains. Int. J. Miner. Process., 165 (2017), pp. 814, / View PDF View article View in Scopus Google Scholar. Menéndez et al., 2018.
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]. This measurement is expressed in kilowatthour per ton (kWh/t), which is the ...
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