Aggregates Manager

February 2014

Aggregates Manager Digital Magazine

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OPERAT 1 Matchup starts at the processing plant Balancing Production and Equipment Utilization T he machine-to-machine matchup of haul trucks to loading units — whether the latter machines are wheel loaders, excavators, or even shovels — is important from the standpoint of using the correct loader or the correct truck bed size, for instance, to allow for proper spotting and load distribution. But why does it really matter if the capacities of these vehicles match? The starting point and reason for mobile machine matchups should ultimately be the production rate of the processing plant. If a loader is undersized for the haul truck fleet, too many loading passes will cause subsequent trucks to line up, waiting for their loads. Similarly, if the trucks are undersized or there are too few trucks, the loader must wait between vehicles. Idling equipment wastes fuel, and bottlenecks at the face, slowing production right from the start. "We generally start with the feed rate for the processing plant and work backward from there to make sure our haul trucks and loadout are properly matched," says Dennis Hunter, regional equipment manager for the Pacific region of Knife River Corp. "We also look at the site plan, looking at how far away the equipment is loading from the plant. If we've enhanced production flow one year, we may see the support equipment can't keep up. If the support is causing bottlenecks, we might add a truck, or we might upsize." AGGREGATES MANAGER Working back from the plant feed rate, Don Gengelbach, equipment manager for Mulzer Crushed Stone, says haul distance from the face to the primary is another major factor when determining truck size and numbers for the fleet. Site studies are a great help in determining mobile equipment needs, he says. "At one time, there was a lot of footwork involved in calculating distances. Now, almost all suppliers have software that will map out your site and calculate distances. It makes it all a lot easier." Hunter says equipment managers rely on the "boots on the ground" personnel at each site to help them assess whether existing mobile equipment is meeting the plant's production needs. Since inexperienced operators can hurt loadout and haulage from a skills standpoint — as well as have a lack of understanding about the operation's overall production goals — Knife River has invested in operator training. "Loader and truck operators can have as much as a 15 percent to 30 percent impact on production. In fact, I've seen as much as a 40 percent impact," says Tim Noon, senior marketing training consultant for Caterpillar, Inc. "It's better to train, train, train your operators, and know they will make sure the equipment produces what it's capable of producing. There's no such thing as a spare truck anymore. You have to be able to produce what you need when you need it." The process of matching mobile equipment is a balancing act that begins with production capability and feed rate for the primary, working backwards from that point. Undersized loaders and trucks slow production as the plant waits on material. Oversized mobile equipment will drive up capital and operating costs, due to idling equipment. 4 Estimation for utilization Producers must take into account the number of hours each unit will work, as well as what the availability and utilization will be, setting aside time for scheduled maintenance. Other considerations include the machine's estimated longevity from any given point. Also, will material characteristic or mine layout changes require a new unit or modifications (attachments, beds, etc.) to existing units?

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