Operational tests have shown that the mill is not capable of processing the harder ore blends at an acceptable rate. The sag mill is 26 diameter x 123 egl and powered by 4,500 hp motor driven by a variable speed lci drive that can control the mill speed from 36% to 80% of critical speed depending on ore type and operational demands. We maintain desired operating conditions by constantly monitoring bearing pressure, mill power, recycle pebbles, mill density, charge toe and mill acoustics. Our sag mill strategies automatically adjust feed rate, mill speed and water addition to reduce upsets, eliminate grindouts, protect linerslifters, and increase tonnage. The operations comminution circuit, which comprises of a semiautogenous sag mill and two ball mills, each with megawatts mw of installed power, was.
The primary grinding circuit can be operated in a pebble crushercrush forward configuration, where the sag mill screen oversize material scats or pebbles is. This process takes place inside the large rotating drum of sag mill which is filled with balls partially. However, the f80 is not enough to represent properly different size distributions, because different size distributions can. Space was made available for future pebble crushing capacity when hard primary skarn ore becomes a significant proportion of the feed blend in later years of operation. Difference between sag mill vs ball mill mech4study. So the answer to your question is yes, a sag mill can be installed in an operation milling 2,000 tpd and it can be operated efficiently if the operators have the knowledge to operate it well. Typical tests required to define a hardness variability function, are given below in figure 1.
I have worked on a 60tph gold operation with a variable speed sag mill. Optimizing your sag mill operation international mining. The optimal performance of ag sag mills is the key to successful plant operation. Comminution, process optimization, precrushing, sag mill capacity increase. The process plant was purchased from the big bell mine in. The matlabsimulink model files were configured to read in the plant data from a. Development of an agsag mill batch test methodology uq espace.
Morrells model morrell, 2011 relates the feed, mill geometry and operating conditions to the speci. Gearless mill drives machinery risk solutions practice 2009 matt dugalic p. Placer dome kidston mine, after being relocated to granny smith for barrick gold and continuing. The following files are included in the appendices cd. This started when the sag mill was originally operating at the. Efficient operation even at higher mill speeds operatorfriendly smooth mill operation significantly improve wear life can be precisely designed to handle the given capacity can be easily retrofitted to existing mills. Sag mill make use of steel balls included with some large and hard rocks for grinding. Sag mill is an investment that can produce handsome returns if extra production is needed or simply to give the mine the option to mill the hardest ores at design throughput rates. Using add reply allows you to attach images or pdf files and provide a more. Hpgrsag circuit from design to operation the commissioning challenge. If the sag mill is not intended to be the ratelimiting step in a process plant, then it is best to adjust the sag load and power to hold a constant tonnage to satisfy another constraint elsewhere. Sag mill optimisation and increasing throughput at the. These mills utilize the balls in making the large fragments of materials broken into pieces.