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Understanding comminution: Compression versus impact crushing

As a kind of basic first rule you could say: Impact crushing is suitable for rocks with a low work index (<12) as well as low silica (<20%) and moisture levels (<5%). Rocks with these characteristics are soft and non-abrasive material, which can be broken easily within the crushing chamber while keeping wear rates at a minimum and produce high ...

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Bond´s work index estimation using non-standard ball mills

The traditional Bond work index proposed by F.C. Bond over 60 years ago is still today a useful tool for characterizing material crushability and grindability in the minerals industry.

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Variability Study of Bond Work Index and Grindability Index on

It is a well-known 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 …

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Comminution Tests Required to Assess the Energy …

The Bond Crushing Work Index (CWI) is then calculated from the formula developed by F.C. Bond CWI = [2.59*K*E b /d/sg] kWh/t (5) Where: E b ... rock breaks. The impact crushing strength in foot-pounds per inch of rock thickness is designated as C, …

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A quick method for bond work index approximate value determination

The Bond work index is a measure of ore resistance to crushing and grinding and is determined using the Bond grindability test. Its value constitutes ore characteristic and is used for industrial ...

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The five types of Work Index

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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Summary of results from Bond crushability and impact load cell …

The traditional Bond work index proposed by F.C. Bond over 60 years ago is still today a useful tool for characterizing material crushability and grindability in the minerals industry.

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Average Bond Work Index in kJ/kg for some minerals and rocks.

For example, E S = 1.27, 0.705, and 0.548Jm −2 for graphite, quartz, and average feldspar, respectively (Brace and Walsh 1962;Zhang and Ouchterlony 2022).

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Table of Bond Work Index by Minerals

This Table of Ball Mill Bond Work Index of Minerals is a summary as tested on 'around the world sample'. You can find the SG of each mineral samples on the other table.

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Crushing and Grinding Calculations by Bond | PDF

Crushing and Grinding Calculations by Bond - Free download as PDF File (.pdf), Text File (.txt) or read online for free. This document presents equations for calculating particle size reduction in crushing and grinding processes. It begins with an overview of the three main theories of comminution: Rittinger's theory which states work input is proportional to new surface area; …

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Energy considerations in compressive and impact crushing of rock

The rock from the crushing plant needs to be reduced typically from the range 1–10 ... C Bond is the so-called work index of the rock, obtained in a test. C Kick and C Ritt are the corresponding work indices in Kick's and Rittinger's formulae, respectively. These models all indicate that as the final product size approaches zero, the ...

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[PDF] Alternative Approaches for Determination of Bond Work Index …

As a fast method, the determination of the Bond index from the Hardgrove index (by calculation) is almost matching with measured Bond's work index. The Bond's work index of the above rock samples calculated from the Hardgrove index value has shown a variation from 7.7 to 10.3 kWh/sh.t. A correlation is found between the friability value and ...

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A meaningful expression between bond work index, grindability index …

The friability value S 7 was measured by the brittleness test (Fig. 1), which gives a value for rock resistance to crushing due to repeated weight-drop (7) impacts.The brittleness test apparatus is designed to determine the grindability characteristics of Tauros limestones, which are used in cement production (Ozkahraman and Sirin, 1998).The dimensions of the mortar, the …

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BOND IMPACT CRUSHING WORK INDEX TESTER

The Pendulum Tester / Bond Impact Crushing Work Index Tester. Working principle Crushing by impact. 76 mm maximum feed size. Test repetition: At least 10, preferably 20 test runs. Adjustable crushing angle; Repeatable crushing results; Safe two-hand operating buttons; The Bond Crushing Work Index (CWI) describes the competency of the ore at ...

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Blastability evaluation for rock mass: review and new tendency

The crushing work index is derived from volume theory. Volume theory posits that the work needed to break rock is proportional to the change in rock mass volume. Bond proposed the crushing work index as a measure of rock mass blastability, using it in the calculation of dressing crushing. The crushing work index relates to the work needed to ...

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Distribution of impact (crushing) work index for …

The traditional Bond work index proposed by F.C. Bond over 60 years ago is still today a useful tool for characterizing material crushability and grindability in the minerals industry.

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Relationship between A*b and Bond impact work index for the …

Also, values of crushing work index (CWi) increased inversely with the A*b breakage index, as commonly observed (Napier-Munn et al., 1996; Tavares and Silveira, 2008). In order to demonstrate the ...

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SAG mills selection methods. III. The F. Bond index …

The method selection depends on the crushing/grinding stage (the power size and the necessary finished class). The crushing work index ( CWi ) is an indicator characterizing the energy amount (kW * h / t) needed to destroy …

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Bond Work Index Formula-Equation

The basic work index equation is: W = 10 Wi/√P – 10 Wi/√F(1) where W is the work input required in kilowatt hours per short ton to grind from 80% passing F microns to 80% passing P microns, and Wi is the work index, or the grinding resistance parameter. It represents the energy input required in kilowatt hours to reduce a s…

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Ore Feed Size * Work Index Hardness: Crushing & Mill Tonnage

The single most common reason for an increase or drop in the production of fines is the WORK INDEX of the ore. If you remember, the work index of the ore is a method of measuring the degree of hardness. As the ore becomes harder the fracture lines in the rock become cleaner or sharper with less crumbling of the face and edges of the mineral.

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Work Index

The self-grinding work index is an extension of the concept of Bond work index. It generally refers to the work index calculated by using Bond's fracture theory on the principle of ore crushing energy consumption according to the W, F, and P data of a small or semi-industrial or industrial self-grinding test. In this kind of test, McPherson small self-grinding closed-circuit …

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Bond Impact Crushing Work Index -Procedure

Sizing a crusher can be done reliably calculated thanks to the Impact / Crushing Work Index and the testwork research done by Fred …

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Testwork: Bond crushing work index

The Bond low-energy impact crushing work index (more informally, the Bond crushing work index) is not as common as the Bond ball mill work index, and it is a notoriously noisy test. The test is a 'per-specimen' test where individual specimens of prepared rock are hand-picked by the test operator and placed into the apparatus.

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Impact work index prediction from continuum damage model of …

Perhaps the most traditional is the one proposed by F.C. Bond over 60 years ago (Bond, 1947, Bergstrom, 1985), which is still used today for characterizing material crushability in the minerals industry. The Bond crushing work index is a measure of material strength and is determined using a simple twin pendulum apparatus and a standard procedure.

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Prediction of Bond's work index from field measurable rock …

Mathematical equations were developed to predict Bond's work index based on rock properties using regression analysis, which resulted a very good correlation co-efficient values. ... (1995) studied the impact of blasting on crushing and grinding and emphasized on development of micro fracture during the blasting to reduce grinding cost. They ...

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Testwork: Bond crushing work index

Crushing mill work index is used in the SAGMILLING Bond/Barratt specific energy consumption model. The work index is used to calculate the energy requirement to break …

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The Importance of Work Index in Mineral Processing

'Work Index' is the amount of energy required to do this work. It is a measurement of how hard the rock is and an expression of the resistance that a material has …

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An energy-driven crushing-plasticity coupling model for grain crushing

Various constitutive modelling methods for porous rocks have been developed, generally aiming to establish an elastoplastic model directly to feature the strength evolution. 37, 38 While these methods offer reasonably accurate predictions to some extent, they often require many parameters, which frequently impedes their application. Moreover, these methods fail to …

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Simplifying the crushing process

Stages of rock crushing It's common to use multiple crusher types within a project and set them up as stations in a circuit format to perform the necessary material reduction work. In many cases, primary, secondary and tertiary stations are established to reduce the rock to the desired size, shape and consistency.

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1 Comparison of measures of rock crushability

6 L.M. Tavares & M.A.C.W. da Silveira The Bond work index has also been used, in conjunction with empirical relationships, to estimate capacity factors of jaw, cone and gyratory crushers

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