What is the importance of the the Bond work index in mineral processing?
What is the importance of the the Bond work index in mineral processing?
Abstract: 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 comminution plants designing.
What is ore grindability?
The resistance of ore samples to breakage (or hardness) is measured through grindability testing. Several grindability tests have been developed over the years for different applications and each test has its own strengths and weaknesses. Grindability testing is a compromise between test cost and its deliverable(s).
What is Bond Index in Limestone?
limestone : andesite = 75 : 25. The Bond work index determination. according to the standard Bond’s test is. done on all these samples with compara- tive sieve size of 74, 105 and 150 microns.
What is a Bond ball mill?
The F.C. Bond Ball Mill is a small universal laboratory mill used in calculating the grindability of all ores. GRINDABILITY IS THE NUMBER OF NET GRAMS OF SCREEN UNDER-SIZE PRODUCED PER REVOLUTION OF THE MILL. Attached file is the Bond index test template.
What is a 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. Shown in the table below is typical Work Index, reflecting the different rock characteristics.
What is the formula for 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 grindability in mineral processing?
A grindability test is a procedure that evaluates the resistance of a material to ball milling. This test is an effective way to calculate and compare the Bond Work Index (BW¡) of different ores. The higher the Bond Work Index, the more difficult it is to grind the material.
How the bond mill grindability test is performed?
Weight and transfer ore to the ball mill. Grind dry for 100 revolutions. Empty the ball charge and ore through a coarse screen to separate the balls from the ore. After mill and balls are swept clean, screen and ground ore through the mesh screen to be tested, using coarser protective screens if necessary.
What does work index mean?
What is the unit of work index?
Numerically, the work index is the energy required in kwh/t to reduce a given material from theoretically infinite feed size to 80% passing 100 microns. The work index of a particular material is determined in the laboratory by conducting the standard Bond grindability test.
What is the work index of gypsum rock?
Table of Bond Work Index by Minerals
| Source 1 | Source 5 | |
|---|---|---|
| Granite | 16.6 | 11.0 |
| Graphite | 48.0 | |
| Gravel | 17.7 | |
| Gypsum rock | 7.4 | 7.0 |
How is grindability calculated?
Ball Mill Grindability (Gpb) = (gm/rev) average of last three grinding cycles to give 250% circulating load. Precautions: There should be consistency in compaction of ores in the 700ml test can. This is normally done by shaking. Accurate observations on grinding revolutions are essential.
What is a material index?
The property or property group that maximizes performance for a given design is called its material index. There are many such indices, each associated with maximizing some aspect of performance. 1 They provide criteria of excellence that allow ranking of materials by their ability to perform well in the given application.
Is the Bond Work Index a material constant?
The Bond work index is not solely a material constant but is influenced by the grinding conditions. For example, the finer the grind size desired, the higher is the kWh/t required to grind to that size. Magdalinovic [38] measured the Bond work index of three ore types using different test screen sizes.
What are the performance indices of materials?
There are many such indices, each associated with maximizing some aspect of performance. 1 They provide criteria of excellence that allow ranking of materials by their ability to perform well in the given application.
What do the values of work indices obtained indicate?
The values of work indices obtained are indications of the efficiencies of the machines. Thus, the equipment having the highest indices, and hence the largest energy consumers, are found to be jaw and gyratory crushers and tumbling mills; intermediate consumers are impact crushers and vibration mills, and roll crushers are the smallest consumers.
