2. Mechanism of Size Reduction: Cutting here the material is cut by means of a sharp blade or blades. EX: Cutter mill Compression in this method, the material is crushed between the rollers by application of pressure. Ex: Roller mill Impact impact occurs when the material is more or less stationary and is hit by an object moving at high speed or when the moving particle strikes a ...
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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
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In conclusion, understanding the different parts of a ball mill and how they work together is crucial for efficient operation and maintenance. The cylindrical shell, grinding media, and material being ground all play important roles in the performance of a ball mill. ... Liquid Oral Preparations PPT PDF: Solutions, Syrups, Elixirs, Emulsions ...
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Size reduction ppt by saroja adepawar. Size reduction ppt. ... Bond crushing law(1952) and work index (intermediate relationship with P = 3/2 = ) ... SOLUTION The critical speed of the ball mill is: The actual speed of the ball mill is: Hz + rps = X 60 = 48 rpm *2 1 cn The critical speed of the ball mill nc= ...
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A ball mill also known as pebble mill or tumbling mill is a milling machine that consists of a hallow cylinder containing balls; mounted on a metallic frame such that it can be rotated along its longitudinal axis. The balls which could be of different diameter occupy 30 50 % of the mill volume and its size depends on the feed and mill size.
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The Bond Index conforming ball charge consists of: 43 x " balls. 67 x " balls. 10 x 1" balls. 71 x " balls. 94 x " balls. The optimum number of grinding balls is 285. 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.
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WioACT Actual Operating Bond Work Index determined from measurements on the circuit (kWh/t) WiRM Bond Rod Mill Test Work Index (kWh/t) WiSTD Standard Circuit Bond Work Index (expected or designed) used for circuit design. Specific energy requirement at the drive pinions. Work Index, Work Index Efficiency, Bond Work Index testing
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: 60% cylinder filled with material. Remaining balls are introduced to cylinder. And closed it with lid. Mills are allowed to rotate on axis. Speed of rotation play important role. At low speed, balls roll over each other and size reduction not occur at optimum level. At high speed, ball will stick to the wall of cylinder and no size reduction occur. At correct speed (optimum speed ...
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A ball mill is a type of grinder widely utilized in the process of mechanochemical catalytic degradation. It consists of one or more rotating cylinders partially filled with grinding balls (made ...
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Applicable reasonably in conventional ball mill and rod mill grinding ( holds good for 5 cm 50 µ ). The power input is computed from Bond work index, feed and product particle sizes by W = ( 10 Wi / 10 Wi / ) (9c) W = power input ; Wi = work index ; F = 80% passing size of feed ; P = 80% passing size of product .
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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.
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Free download as Powerpoint Presentation (.ppt / .pptx), PDF File (.pdf), Text File (.txt) or view presentation slides online. Scribd is the world's largest social reading and publishing site. Open navigation menu.
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Here are ten ways to improve the grinding efficiency of ball mill. 1. Change the original grindability. The complexity of grindability is determined by ore hardness, toughness, dissociation and ...
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Wm = Wi ( 80P 10 80F 10 ) (1) where: Wm is mill specific motor output power (kWh/t), Wi is the Bond ball mill work index (kWh/t), P80 is sieve size passing 80% of the mill product (µm), F80 is sieve size passing 80% of the mill feed (µm), The "efficiency factors" (Rowland, 1975) modify equation 1 so that it caters for circuit ...
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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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Principle of Ball Mill: The size reduction in the ball mill is a result of fragmentation mechanisms (impact and attrition) as the balls drop from near the top of the shell. Mixing of feed is achieved by the high energy impact of balls. The energy levels of balls are as high as 12 times the gravitational acceleration.
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21 CONCLUSIONS Continued In the present work, equations were also derived, giving: zthe ballmill power drawP as a function of its dimensions: internal mill diameter D and length L, zthe ballmill power drawP as a function of the feed D f (mm) and the product size d (mm), the Bond work index w i (kWh/short ton) and the mill throughput T (short ton/h), zthe ballmill dimensions (D and L), when ...
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CERAMIC LINED BALL MILL. Ball Mills can be supplied with either ceramic or rubber linings for wet or dry grinding, for continuous or batch type operation, in sizes from 15″ x 21″ to 8′ x 12′. High density ceramic linings of uniform hardness male possible thinner linings and greater and more effective grinding volume.
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The energy consumption in the ball mill was found to be kWh/t of ore with a targeted product size below 1 mm. The BWI of the ores varied from to kWh/t to reduce the particle size below 100 μ m, but in real time, the energy consumption is very high compared with the reported value of kWh/t.
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In the prerequisite module entitled "Work Index Efficiency", you have learned about work index analysis* to define overall grinding circuit efficiency. In rod milling, you can use work index analysis to relate design and operating variables to overall circuit efficiency. However, you cannot use work index analysis for the same purpose on ball mill
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Ball tube Bowl Hammer mill Ball race mill millDominating Attrition Crushing Impactprinciple; 11. .... Best ppt on Presentation on Coal handling plant. Why is the Bond Ball Mill Grindability Test done the way it is done? Mill Work Index which expresses the resistance of a material to ball milling. This Index is ...
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They extend to almost the full length of the shell and occupy about 35% of the shell volume. In such mills, attrition forces predominate but impacts also play a part in size reduction. They are classed as intermediate grinders and are more useful than ball mills for milling sticky materials. Selection Criteria for Sizereduction Equipment
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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
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For any circuit, whether a crushing circuit, a rod mill, or a closed ball mill circuit, the Work Index always means the equivalent amount of energy to reduce one ton of the ore from a very large size to 100 um. The sample was received crushed appropriately for the ball mill test.
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the ball mill test, the test can also be closed with various sieve sizes, but for AG/SAG mill analyses the standard 14mesh ( mm) sieve is typically used. The rod mill work index is computed with an equation very similar to that of the ball mill test, as follows: The rod mill work index is also normally distributed. The database average and ...
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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. These equation application methods are used to process <1/2″ ore samples in a Ball Mill using a standard ball charge.
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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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expected from their Bond ball milling work indices. In fact, the average ratio of DWi to Bond ball mill work index was at the 90th percentile of a much larger database. This result indicates that the SAG milling power requirements for these ores is likely to be much greater than what would be expected from the Bond ball mill work index.
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Indeed, it is claimed that the Bond work index of the HPGR product is significantly lower than the product of conventional crushers (Norgate and Weller, 1994, Pazelt et al., 1995). ... Ball milling is usually used to achieve a finely ground product for pelletizing when the pellet feed is too coarse. For example, if sintering fines are to be ...
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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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In order to maintain throughput, a VTM1250 was installed in semiparallel with the existing ball mill circuit. The VTM1250 accepted undersize from a new screen installed on a portion of the ball ...
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The basic parameters used in ball mill design (power calculations), rod mill or any tumbling mill sizing are; material to be ground, characteristics, Bond Work Index, bulk density, specific density, desired mill tonnage capacity DTPH, operating % solids or pulp density, feed size as F80 and maximum 'chunk size', product size as P80 and maximum a...
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Generally, filling the mill by balls must not exceed 30%35% of its volume. The productivity of ball mills depends on the drum diameter and the relation of ∫ drum diameter and length. The optimum ratio between length L and diameter D, L: D, is usually accepted in the range
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A material supplier from Belgium would like to produce limestone powder for his custome...
India is rich in various mineral resources and it is an important mineral processing market
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