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. Different materials are used as media, including ceramic balls, flint pebbles ...
WhatsApp: +86 18838072829Which of the following gives the work required for size reduction of coal to 200 mesh in a ball mill most accurately ? A. Rittinger's law. B. Kick's law
WhatsApp: +86 18838072829So, our equation of motion is: F c = m a c, F N + m g = m v 2 r. To find the critical speed, we set the normal force to zero, as we did with the tension before, and we arrive at the same equation for the critical speed: 0 + m g = m v c 2 r, v c = g r. So the critical speed of the passenger is v c = m s 2 ⋅ 15 m = 12 m s.
WhatsApp: +86 18838072829Similarly, from Fig., it would appear that the throughput varies directly with the speed of rotation, for speeds up to about 70% of the critical. At some point above this speed the curve would be expected to become horizontal, since at the critical speed the charge would be spread around the mill and horizontal flow would then be unlikely.
WhatsApp: +86 18838072829Management. Law. Philosophy. Agriculture. Sociology. Political Science. Pharmacy. The energy consumed by a ball mill depends on a) Its speed b) Its ball load c) The density of the material being ground d) All of the above.
WhatsApp: +86 18838072829Number, size and mass of each ball size depends on mill load and whether or not the media is being added as the initial charge. For the initial chargin of a mill, Coghill and DeVaney (1937) defined the ball size as a function of the top size of the feed,, ... However, after reaching a critical speed, the mill charge clings to the inside ...
WhatsApp: +86 18838072829In practice, the optimum operating speed is about 75% of the critical speed and should be determined under the plant operating conditions. c) Impact Percussion Mill When two bodies collide, impact, they compress each other until they have the same velocity and remain in this state until restitution of the compression begins.
WhatsApp: +86 18838072829The formula for calculating critical mill of speed: N c = / √ (D d) Where: N c = Critical Speed of Mill. D = Mill Diameter. d = Diameter of Balls. Let's solve an example; Find the critical speed of mill when the mill diameter is 12 and the diameter of balls is 6. This implies that;
WhatsApp: +86 18838072829The formula to calculate critical speed is given below. N c = /sqt(Dd) N c = critical speed of the mill. D = mill diameter specified in meters. d = diameter of the ball. In practice Ball Mills are driven at a speed of 5090% of the critical speed, the factor being influenced by economic consideration.
WhatsApp: +86 188380728291. Mechanical Operations MCQ on Size Reduction. The section contains Mechanical Operations multiple choice questions and answers on solid properties, particle sizes, size reduction and its mechanism, energy utilization, crushing efficiency, size reduction energy and equipment's, crushers, intermediate and fine crushers, ball mill and its advantages, tumbling mill action, ultra fine grinders ...
WhatsApp: +86 18838072829Grinding efficiency of a ball mill is of the order of _____ percent. a) 15 b) 4050 c) 7580 d) 9095. Which of the following gives the work required for size reduction of coal to 200 mesh in a ball mill most accurately ?
WhatsApp: +86 1883807282922 May, 2019. The ball mill consists of a metal cylinder and a ball. The working principle is that when the cylinder is rotated, the grinding body (ball) and the object to be polished (material) installed in the cylinder are rotated by the cylinder under the action of friction and centrifugal force. At a certain height, it will automatically ...
WhatsApp: +86 18838072829In total, 165 scenarios were simulated. When the mills charge comprising 60% of small balls and 40% of big balls, mill speed has the greatest influence on power consumption. When the mill charge is more homogeneous size, the effect of ball segregation is less and so the power consumption of the mill will be less affected.
WhatsApp: +86 18838072829The approximate horsepower HP of a mill can be calculated from the following equation: HP = (W) (C) (Sin a) (2π) (N)/ 33000. where: W = weight of charge. C = distance of centre of gravity or charge from centre of mill in feet. a = dynamic angle of repose of the charge. N = mill speed in RPM. HP = A x B x C x L. Where.
WhatsApp: +86 18838072829Optimizing the critical speed of a ball mill can improve grinding efficiency and product quality by ensuring the grinding balls are effectively lifted and distributed for optimal grinding. ... blending, and mixing. The application of ball mills depends on the industry and the specific requirements of the process. In mining, ball mills are used ...
WhatsApp: +86 18838072829Where, is the critical speed in rev/sec, is acceleration due to gravity, m/s2, R is radius of the mill, m and r is radius of the ball, m. Tumbling mills run at 65 to 80 percent of the critical speed, with the lower values for wet grinding in viscous suspensions. Ultrafine Grinders
WhatsApp: +86 18838072829Law. Philosophy. Agriculture. Sociology. Political Science. Pharmacy. For efficient grinding, ball mills must be operated a) At a speed less than the critical speed b) At a speed more than the critical speed c) At a speed equal to the critical speed d) With minimum possible small balls.
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WhatsApp: +86 18838072829Commerce. Management. Law. Philosophy. Agriculture. Sociology. Political Science. Pharmacy. In case of a ball mill, a) Coarse feed requires a larger ball b) Fine feed requires a larger ball c) Operating speed should be more than the critical speed d) None of these.
WhatsApp: +86 18838072829The operating speed of a ball mill should be __________ the critical speed. A. Less than. B. Much more than. C. At least equal to. D. Slightly more than. Answer: Option A. This Question Belongs to Chemical Engineering >> Mechanical Operations.
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