Autogenous Grinding. a grinding process in which large pieces of the material to be ground—ores and rocks-serve as the grinding medium; the process is carried out in drum mills. In autogenous grinding, a distinction is made between ore and ore-pebble grinding. Ore grinding is carried out in mills with a large diameter (up to 12 m) and short ...on Fully Autogenous Mills René Coetzee ... FAG Mill Specification 9.75m diameter vessel/drum 2 x 3.5MW, fixed speed, induction motors per mill ROM grinding @ 750 tons per hour (no balls/rods) ... 1.2 kWh/ton (12.1%) equating to R10-million since ITD

The aspect ratio (mill diameter/mill length) of autogenous and semi autogenous mills varies widely and can be as high as three or as low as 0.5. The literature on the subject of what effect aspect ...where m p is in kW; D is internal mill diameter (meters), L is internal mill length (meters); J is total fractional charge loading of the mill; J B is the fractional mill filling by balls; ε B is the effective porosity of the charge, taken as 0.3; ρ s and ρ b are true densities of rock and balls (tons per cubic meter), respectively; w c is the weight fraction of rock in water and rock in ...

Mill inside liner diameter (3.9 m - 2 x 0.185 m), ... Short ton to metric tone conversion fac tor, k. 1 ... The special characteristics of the Autogenous mill are stated, and a suitable type of ...autogenous mills . 8. ... dimensions: internal mill diameter D and length L, ... (12, 14, 16 and 18 kWh/short ton) values of clinker work-indices w i, is shown in Figure 5. 2.

Semi-Autogenous Mill Note the size of the mill: Why does the diameter need to be so big? [image: (135-6-2)] ... (Wi, normally expressed in kWh/ short ton). Other established methods, for instance Hardgrove Index, population balance. Scale Up in Sizing for Grinding Mills.Mill Power Capability - Autogenous Mill General Equation:- PowerDraw MillVolume*Chargedensity*D*Rg*n 1200 = Rg is a distance from the centre of gravity of the charge to the centre of the mill for a 1m diameter mill and n is the number of revs per minute of the mill - Morgardshammar/Marcy equation. Mill diameter inside liners - D

An ABC (Autogenous Mill-Ball Mill-Crusher) grinding circuit was chosen. The original mill contained three completely independent grinding circuits, each containing one 9.75 m diameter by 3.96 m long fixed speed autogenous mill, one 4.72 m diameter by 6.71 m long ball mill and one 2.13 m diameter short-head cone crusher.a rod mill can not be built too big. A shell length above 6100 mm can not be recommended. As the length to diameter ratio of the mill should be in the range of 1,2-1,5, the biggest rod mill will convert maximum 1500 kW. Rod mills are used for primary grinding of materials with a top size of 20-30 mm (somewhat higher for soft materials).

an 8 m diameter SAG mill with LID = 0.5 grinding a copper ore, and predicted maximum capacity and minimum kWh/ton at about 6070 ball load at 25070 total filling. Two FAG mills of LID = 2 were necessary to give the same capacity, and the simulations indicated a lower kWh/ton for these mills. For this ore, both systems were technically feasible.Since the days of mandatory high cost pilot plant testing in 6 ft × 2 ft SAG mills autogenous ... and Hinkfuss (1978), claimed the 18 ft diameter mill size was ... ball mill work index was averaging only 11.6 kWh/t, which is not hard. A rod mill work index fi gure was not found but was thought to be in the 16 kWh/t to 18 kWh/t range.

In autogenous mills the diameter is greater than the length. They can be as much as 40+ feet in diameter. ... The average of all three tests gives a short mill power of 9.5 KWH per ton compared with 11.35 KWH per ton for the longer mill circuit. Again, however, the effects of the finer grind become apparent when power per ton of minus 200 mesh ...ABC closed circuit, Autogenous-Ball-Mill-Crusher. Another similar technique is the ABC open circuit where the crusher product feeds the ball mill rather than the autogenous mill. Crusher product is typical feed to a ball mill using large diameter balls but not much grinding of 20-25 mm ore can be accomplished in an autogenous mill.

8-3 Centrifugal force outward Fc mp& 2 Dm 2 (8.1) & is the angular velocity, mp is the mass of any particle (media or charge) in the mill and Dm is the diameter of the mill inside the liners. Gravitational force Fg mpg (8.2) The particle will remain against the wall if these two forces are in balance ie.autogenous (SAG) Mill via an utilized method. Miduk copper concentrator is located in Kerman Province, Iran, and its size reduction stage includes one gyratory crusher which feeds one SAG mill (9.75 ... mills diameter (m). Unfortunately, it is not possible to empty ... moisture were 7 tons (ball size was 100 mm) per week, 720 t/h and 5%, ...

2.1. AUTOGENOUS (AG) AND SEMI AUTOGENOUS (SAG) MILL OPERATION Semi autogenous grinding is one of the most used processes for comminution. The process involves feeding rock particles and water into the grinding mill containing a fraction of steel balls usually below 10% and running at a fraction of its critical speed.xSemi-autogenous grinding with "as is" ore and 127 mm diameter steel balls With the exception of the two variations for primary grinding, the process flowsheet in all tests was the same. The primary mill used was a 1.67 metre diameter mill with an effective grinding length of 1.16 metre.

Primary autogenous and semi-autogenous mills in Sweden and South Africa have much larger length to diameter ratios than mills in the United States and Canada. At Boliden's Aitik plant in Sweden, the primary mills are 20 feet in diameter by 34 feet long. Some of the mills purchased recently for installation in the U.S. and Canada are trending ...An appropriate amount of steel ball is added to the autogenous mill to form the so-called semi autogenous mill. ... i.e. tons / kWh. ... If the proportion of large-diameter steel balls in the mill exceeds 70%, the action area of the grinding ball will be reduced. ...

A generalized SAG mill power draw equation developed by Austin, is given by: where the parameters used in the model are defined as: mp= net mill power (kW) K = a constant (kW/ton m0.5) D = mill internal diameter (m) L = mill length (m) J = fractional volume of mill filled by total charge. εB = effective porosity of the total charge.part of gold recovery requiring crushers, large diameter semi-autogenous grinding (SAG) mills and ball mills with up to 12,000 kW motors. Ore grinding can account for 60% of a site's electrical power load and more than 35% of the operation's greenhouse gases (GHG) as measured in tonnes of CO 2 equivalent.

Jan 01, 2016· For autogenous mills, like the dry Aerofall mills, MacPherson and Turner established that the power consumption was a function of mill diameter and length. For dry commercial AG mills they derived the power as (9.8) P M = 0.992 L D 2.8 ρ c where ρ c = bulk density of the mill charge (rock plus balls and water) (t/m 3 ) CHATAUTOGENOUS GRINDING MILL- Designed to do autogenous or semi-autogenous grinding, with the proper length to diameter relationship, contour of the mill heads, and placement of internal lifters and deflectors. Reduction or elimination of grinding media ... 360kgs./hr. to 725 metric tons/hr. 020A 020B 020C 020D 020E 020G 020H PAGE 3

Autogenous Mill is a new type of grinding equipment which has functions of crushing and grinding. Its working principle is basically the same as that of ball mill. Ore itself is the medium, through mutual impact and grinding to achieve ore grinding. The cylinder has a larger diameter. Read MoreFurthermore, in this way the magnitudes of energy requirement (kWh/ton, feed rate (tph), and particle-size distribution in the mill discharge, which normally varying greatly in conventional autogenous grinding processes, can be stabilized to a level which is extremely advantageous from …

(18 inch) diameter by 152mm (6 inch) long test mill. Starting with minus 1.25 inch crushed ore and 16% by ... depending on the product size produced in a semi-autogenous mill 3. MacPherson must have known this and ... Where W is the grinding mill work input in kWh/t.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 and finally the type of circuit open/closed ...

The grinding circuit comprises one 8530 mm diameter x 3650 mm semi-autogenous mill driven by a 3954 kW variable speed dc motor, and one 5030 mm diameter x 8340 mm secondary ball mill driven by a 3730 kW synchronous motor.Example Two compartment cement mill Diameter 4.05 m Length 12 m Filling degree 196 tons at 30 filling degree Mill speed 16.27 rpm C 0.223 from the figure Then K 0.223 196 4.05 16.27 2.88 KW 8.2 Calculation of the Specific Consumption of Energy per Ton of Clinker The specific consumption of energy per ton of clinker. Live Chat