How do you calculate work index?
How do you calculate work index?
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 calculation is based on the size-energy relationship e1,2=C.
What is the meaning of work index?
‘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 to crusher. It shows for example, that their is more energy required to crush Basalt then Iron Ore.
What is F80 in mining?
F80 is the 80% passing size of the circuit feed, and P80 is the 80% passing size of the circuit product, in microns. For example, a grinding circuit is processing 450 t/h (of dry feed) with a mill drawing 3,150 kW (at the pinion).
What is the importance of the the bond work index in mineral processing?
Bond work index (Wi) can be considered as one of the most important affecting factors in the design of grinding systems which express on the value of energy (kwh) consumed per ton of the ground ore.
What is Bond ball mill work index?
This Grindability Test or Bond Ball Mill Work Index Procedure is used to determine the Bond Work Index of minus six mesh or finer feed ore samples. GRINDABILITY IS THE NUMBER OF NET GRAMS OF SCREEN UNDER-SIZE PRODUCED PER REVOLUTION OF THE MILL.
What is Bond Index in Limestone?
Abstract—The Bond work index is a research methodology, which is widely used for the estimation of power required to grind the materials. In this regard calculation of work index of limestone made by standard Bond grindability test. Ball mill was employed to conduct the grinding test of seven different samples.
What is Bonds Law of size reduction?
Bond’s. Law: The work required to form particles from very large feed is proportional to the square root of the surface-to-volume ratio. E = KBfc [(1/L2)1/2- (1/L1)1/2] Rittinger’s Law — The energy required for reduction in particle size of a solid is directly proportional to the increase in surface area.
What is P80 in particle size?
Grinding time was altered to produce two different grind sizes (P80 = 150 and 106 µm).
What is critical speed of ball mill?
A Ball Mill Critical Speed (actually ball, rod, AG or SAG) is the speed at which the centrifugal forces equal gravitational forces at the mill shell’s inside surface and no balls will fall from its position onto the shell. The imagery below helps explain what goes on inside a mill as speed varies.
What is Kick’s law?
Kick’s Law — The amount of energy required to crush a given quantity of material to a specified fraction of its original size is the same, regardless of the original size.
What is the significance of a large work index of an ore sample?
The index gives the energy required to reduce a limit weight of material from a theoretical infinite size to 80% passing 100μm. We should note that the higher the value of the work index, the more difficult it is to grind the material.
How do you measure a ball mill?
Based on his work, this formula can be derived for ball diameter sizing and selection: Dm <= 6 (log dk) * d^0.5 where Dm = the diameter of the single-sized balls in mm. d = the diameter of the largest chunks of ore in the mill feed in mm.
How is the Bond Work Index of an ore determined?
The Bond work index is a measure of ore resistance to crushing and grinding and is determined using the Bond grindability test.
How is the th e Bond Work Index calculated?
Th e Bond Work Index is calculated using the formula: undersize product (µm). change of the Bond work index (Magdalinovic et a l., 2012). Due to the Bond test 1985). unknown ore grindability are compared to reference ore of known grindability. This procedure can be carried out in any laboratory ball mill. Horst and Bassarear (1976)
How is Bond work index related to screen size?
Magdalinovic [38] measured the Bond work index of three ore types using different test screen sizes. He produced a correlation between the mass of test screen undersize per revolution, G, and the square root of the test screen size, D: The constant K1 is dependent on the ore type.
How is Bond work index related to Rittinger’s law?
The Bond work index (Bond, 1960) is based on Bond’s law, which states that the energy consumed is proportional to the 1.5 power of particle size rather than the square of Rittinger’s law. Accordingly, the energy consumed in reducing the particle size from x F to x p (both measured as 80% undersize) is given by
