A mineral of was crushed and the average product size of the largest fraction was mm. It was fed to a wet overflow ball mill of m and ground in closed circuit at 75% of the critical speed. The work index of the mineral was kWh/t. Estimate the largest size of makeup ball that should be used. Solution
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
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 ...
A Bond Ball Mill Work Index test is a standard test for determining the ball mill work index of a sample of ore. It was developed by Fred Bond in 1952 and modified in 1961 (JKMRC CO., 2006). This index is widely used in the mineral industry for comparing the resistance of different materials to ball milling, for estimating the energy required ...
Ball Mill. Group No. 3. LOGO Contents. Introduction Types and Process. Principle of work. Description of Ball mill Design and Cost Introduction. It is a device used for size reduction, It can reduce sizes up to a tenth of a micron. Cylindrical in shape. Rotates on a horizontal axis. Partially filled with the material to be ground and the grinding medium.
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 ...
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
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 ...
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
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.
Working of ball mill. The drug to be ground is put into the cylinder of the mill and rotated. The speed of rotation is very important. The speed of rotation is very important. At a low speed, the mass of balls will slide or roll over each other and only a negligible amount of size reduction will occur. At a high speed, the ball will be thrown ...
The Bond ball mill grindability test is one of the most common metrics used in the mining industry for ore hardness measurements. The test is an important part of the Bond work index methodology ...
Similar to a Comparative Work Index, this test is an open circuit dry batch grindability test run in the standard Bond Ball Mill for a set time. It can be used at mesh sizes from 65 to 200 mesh (normally 100 mesh). The test requires calibration against the standard Bond Ball Mill Work Index test to estimate the Work Index.
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.
Based on the standard procedure defined by Bond, the ball mill work index is determined by simulating a closed cycle dry grinding in a laboratory Bond ball mill until a stable circulating load of 250% is established (Bond, 1949, Bond, 1952, Bond, 1961). The ball mill work index is determined by Eq. (10). The recommendation is the ball mill ...
12. If the rate of feed increased, coarser product will be obtained and if speed of rotation is increased the fineness for a given capacity is increases. During grinding, the balls themselves wear and are continuously replaced by new ones so that mill contains balls of various ages. Ball mill produces 1 to 50 ton/hr of powder and energy requirement of the ball mill is about 16 kwh/ton.
Size reduction. Zeki Berk, in Food Process Engineering and Technology, 2009. Energy consumption. As a rule, size reduction operations are heavy in energy consumption (Loncin and Merson, 1979; Hassanpour et al., 2004).As an example, the cost of energy is the single largest item in the total cost of wheat milling. Milling of one bushel (approx. 27 kg) of wheat requires kwh of electric ...
A ball mill, a type of grinder, is a cylindrical device used in grinding (or mixing) materials like ores, chemicals, ceramic raw materials and paints. Ball mills rotate around a horizontal axis, partially filled with the material to be ground plus the grinding medium.
A standard Bond mill (Fig. 1) was designed to perform the work index tests and determine the energy consumption of various s mill has a round internal housing at the corners, has no lifters, and is for dry grinding. The inner diameter and the length are m, and the ball load is % of mill volume (equaling a total weight of kg).
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 ...
The popular size reduction equipments for agricultural produce, viz., hammer mill, ball mill, burr mill, jaw crusher, gyratory crusher, crushing roll, cutter mill, Reitz mill, and colloid mills, are explained using schematic diagrams. ... Another empirical form of Bond's equation is written in terms of constant work index (W i). Work index ...
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.
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 ...
BOND BALL MILL GRINDABILITY TEST The Bond Ball Mill Grindability Test is performed according the original Bond procedure. It requires 10 kg of minus 6mesh material that is preferably prepared at the testing facility. The Bond Ball Mill Work Index has been widely used for ball mill sizing, and is also utilized in computer simulation.
Table (): Bond's work index for some materials Material Work index Bauxite Cement clinker Clay Coal Granite Gravel ... b Ball mills, Tube mills and Rod mills. c Roller mills and bowl mills d Attrition mills 3Ultrafine grinders:
The ball mill work index laboratory test is conducted by grinding an ore sample prepared to 100% passing mm to product size in the range of 45150 µm, thus determining the ball mill w i .
Grinding in ball mills is an important technological process applied to reduce the ... (coefficient of reduction), the work index of the material, the mill shaft power and the specific gravity of the material. These parameters are thoroughly studied in [4, 5] and an empirical relation is suggested expressing the mill capacity as a ratio ...
A Bond Ball Mill Work Index test may be required for the design of a new mineral processing plant . It is determined by Bond Ball Mill Grindability test in a lab using a Bond Mill. Grindability is the number of net grams of ( screen ) undersized product per revolution of the mill . Corrections are done if P is less than 80% passing 70μ size ...
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 ...
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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