Factors Influencing the Optimization of Autogenous Grinding Mills
The Stekenjokk plant employs a system with automatic support of the secondary mill with pebbles from the primary autogenous mill. As well as in the Aitik case the Stekenjokk plant has reached its rated capacity and performance after a short running in period. Capacity Variations and Feed Size All of these autogenous installations have been […]
How to Measure the Impact Forces in Ball Mills
Of many physical parameters critical to design of grinding processes, impact of grinding media is among the most difficult to measure or predict. Yet impact of falling grinding balls, pebbles, or rods accomplishes the fine grinding essential to metallurgical recovery of most important minerals. Unfortunately, the same impacts that break ore fragments deform or crack […]
Advanced Grinding Circuit Control Strategies for Mining Operations | 911 Metallurgist
Cyprus Pima has two concentrators, one with a conventional crushing-grinding circuit and the other using semiautogenous grinding followed by ball mills. Old Mill Flowsheet The original mill was constructed in 1956 but has been expanded three times so that by 1967 there were ten sections having a total capacity of 36,000 tpd. Subsequent revisions have […]
Gearless Ball Mill Operation
The reliability of large diameter, high horsepower ball mill is paramount when large production and minimum downtime is required. The 17 ft. x 56 ft. double compartment ball mill at St. Lawrence Cement Company has the first gearless drive built in North America and has the world’s largest hydrodynamic bearings currently built and running. The machine […]
Ball Mill Charge Control
Direct control of ball mill inventory has been the goal of a number of investigators over many years. To put some numbers on these concepts consider a 250 ton mill with 3 nominal 10 ton inventory that should be controlled to one part in forty that is a 2.5% band or ¼ ton. This will require a […]
Two Stage SAG Grinding Circuits VS ABC Circuits
Grinding facilities are arranged either as single-stage circuits, or in a two-stage configuration with ball mills. Another major concentrator, designed with an autogenous mill, ball mill, crusher (ABC circuit), is presently under construction and scheduled for start-up late this year. The host rock of the Island Copper deposit is a highly fractured fine-grained andesite. A […]
How Mineral Behave in Grinding Circuit
A closed grinding circuit, typified by a ball mill-cyclone combination, is often required to treat a feed comprised of a variety of minerals of differing properties. Usually, the individual behaviour of the minerals is not assessed, a procedure which requires sizing and metal or mineralogical assaying of each size fraction. Further, sizing is frequently by […]
Increasing Grinding Throughput with Grinding Aids
Laboratory and industrial grinding tests have shown that the process of size reduction can be significantly influenced by chemicals added to the powder or slurry being ground. The terms grinding aid or grinding additive refers to a substance which when mixed into the mill contents causes an increase in the rate of size reduction. The […]
Ball Mill Charging System
Mill ball charging systems have undergone little change during the past two decades. Most operations utilize a locomotive/ball car combination to load and haul charges from the ball storage bin to the mill charging boxes or, alternatively, transport charges to the charging boxes by means of a ball bucket handled by bridge crane. The grinding […]
Automatic Grinding Mill Control
There are presently in use many grinding mill control schemes and concepts. In this case, one operating method of controlling the particle size of the cyclone overflows for proper metallurgical results and controlling the level of the cyclone feed sump and new feed rate to obtain lowest unit cost of finished (ground) material which is […]