Ball-limited circuits (where the T 80 hits the lower limit) will result in the charge level in the SAG mill dropping until its power draw matches the throughput limit dictated by the ball mill. It is important to realize that once the SAG mill charge level drops to be equal to the ball charge, the model will be operating "out of range" and the ...
operation of SAG mills. SAG mills are currently the technology of choice in hard rock milling operations for reducing primary-crushed ore to ball mill feed. In recent years, the trend has been towards larger-sized SAG mills with diameters of 10.4 m (34 ft) and above, with the largest being 12.2 m (40 ft) in
The ball charge is a function of the bulk fraction of the SAG mill volume (Jb) occupied by balls; the ore retained in the mill is the result of the volumetric filling which depends on the ore size distribution (specially the % +6″ and the % −6″ +1″), on the rotational speed (N/Nc) and on the solid concentration by weight fraction inside ...
The mill building was energized with a temporary 25kV power line, which enabled interior and exterior lighting and also the use of critical components such as the overhead crane. The foundations for the Ball and SAG mills were prepared with concrete and grout works, as well as anchor bolt and sole plate installation.
Power drawn at the pinion is 448 kW, 13.617 kWh/tonne (SAG mill) and 570 kW, 17.325 kWh/tonne (ball mill) when processing 32.9 mtph, for a total of 30.942 …
The biggest characteristic of the sag mill is that the crushing ratio is large. The particle size of the materials to be ground is 300 ~ 400mm, sometimes even larger, and the minimum particle size of the materials to be discharged can reach 0.1 mm. …
four simulation tasks, consisting of AG, SAG and ball mills are reported. The simulation of AG and SAG mills are completed in less than 8 hours. The ball mill simulation with 1.25 million spheres is completed in 27 hours. In the near future, these compute times can be halved with the advances in graphic card hardware. KEYWORDS
Attrition mill is a type of grinding mill by kinds of media to crush lump to powder-like substances. The impact can be rock on rock such as in an Autogenous Grinding (AG) mill, rock and a small ball charge (~10%), used in Semi Autogenous Grinding (SAG) mills, balls of various sizes in Ball Mills and less commonly these days, steel rods in Rod Mills.
In semi-autogenous grinding (SAG), the grinding mill inventory, (i.e. volume of total charge, volume of ball charge, etc.) is important in determining the optimum operating condition for maximum production (tph), minimum specific energy (kwh/t) or lowest cost ($/t). A two-dimensional graphical method is presented for determining the actual ball charge within the total charge when parameters ...
mill speed and shell liner/lifter simulations and, particularly, ball charge volume and ball top size, both of which are dependent upon the contingency applied to the transfer size in the SAG circuit product. Iterations of these para-meters can be performed in some models (e.g., DJB's "Reduced Recovery" and "Millpower2000") to determine
The ball mill accepts the SAG or AG mill product. Ball mills give a controlled final grind and produce flotation feed of a uniform size. Ball mills tumble iron or steel balls with the ore. The balls are initially 5–10 cm diameter but gradually wear away as grinding of the ore proceeds. The feed to ball mills (dry basis) is typically 75 vol ...
respect with SAG mills being increasingly less sensitive as the ball charge is increased (Morrel S and Valery W, 2001). 2.2. EFFECT OF FEED SIZE DISTRIBUTION ON SAG MILLING The qualitative effect of changes in particle size distributions (PSD) on the SAG mill performance can be addressed by using the grind curves.
The handling of heavy steel balls can be a safety issue when drums of balls are hoisted and tipped, often manually, into chutes and mill outlets. Transmin can custom-engineer steel ball storage vessels to suit any operation. This includes hoppers and trays …
A comprehensive energy study was carried out for the Red Chris mill, which processes copper-gold ore at a rate of 30,000 tonnes per day (t/d) and is located in Northern British Columbia. The study focused on identifying opportunities for energy conservation in the semi-autogenous grinding (SAG)-ball mill and regrind circuits.
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 dia.(m)*3.88 length(m)) following two parallel ball mills (5dia.(m)*7lenght(m)). After SAG mill, a
· Ball mill and sag mill girth gear, trunnion head. Both the ball mill and the sag mill can process non-metals, ferrous metals, non-ferrous metals, rare metals, etc., and are divided into dry and wet types to meet the needs of various materials.
The ball charge and ore charge volume is a variable, subject to what is the target for that operation. The type of mill also is a factor as if it is an overflow mill (subject to the diameter of the discharge port) is usually up to about 40-45%. If it is a grate …
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 …
automated ball chargers Complete ball handling systems from delivery, to mills Transmin specialises in a range of systems available to safely store and feed steel balls into mills or conveyors – from simple kibbles, through to complex handling systems comprising …
According to available literature, the operating speeds of AG mills are much higher than conventional tumbling mills and are in the range of 80–85% of the critical speed. SAG mills of comparable size but containing say 10% ball charge (in addition to the rocks), normally, operate between 70 and 75% of …
In ball milling applications, the diameter of the balls, mill and throw action of the charge provides a low-impact environment– hence maximum abrasion resistance of steel balls is the desired characteristic. CHEMISTRY & HARDNESS High carbon …
Charge Motion inside a SAG Mill. For proper design of SAG mills and other types of grinding mills, the operating conditions have to be defined. Predicting the …
SAG mills (semi-autogenous milling) is a type of grinding carried out with a small amount of ball charge and with the help of bigger parts crumbling the smaller parts of ore. In addition to being preferred in gold, copper, platinum and silver mines, SAG MILLS are preferred in mines such as lead, zinc, alumina and nickel. The SAG mills are ...
Low capital investment alternatives such as the optimisation of the SAG mills lifter/liner design, pulp lifters, ball charge level and ball size were studied in the SAG mill circuit as well as an ...