Prairie Dawg Practical
by Tim Holmberg, DEMI Equipment
I would imagine the word “feeder” outside of a gravel or mining installation would throw a few people off when mentioned. Why would we use that word in relation to digging and hauling dirt out of huge hole in the ground? After about 30 minutes or so the word will start to gain some valuable meaning and purpose relating to earth digging for both mining and gravel operations. The next question is what does a feeder do and how does it work? Are there more than one type or style of feeder and if so, are there noticeable differences between each?
Let’s just say that without a feeder the rest of the operation would not exist — as the feeder is the very first piece of equipment the operator dumps his material into right out of the hole.
Feeders can be portable or stationary. This preference is usually determined from the beginning stages of setting up a mining or aggregate installation. If the installation is going to cover many miles of ground, it would be best to utilize a feeder that is somewhat portable and can be moved every so often to eliminate excessive driving of loaders or haul trucks. Feeders are often associated with overland conveyors if operations cover miles and miles of surface area. Overland conveyors working in conjunction with feeders can and will save maintenance and fuel costs every day — so the advantage to having both is huge versus wear and tear to the rolling stock or man power.
Portable feeders are usually lighter in construction because they have to be transported in one-piece from time to time to an entirely new location — usually on a flatbed. These feeders will generally operate at lower cost but also equate to less productivity and less energy to operate. So, it is more helpful to acquire the lighter-duty belt feeder when starting out on a smaller budget.
Stationary feeders — AKA vibratory grizzly feeders (VGF) — are much heavier. The supporting structure being made of heavy-duty structural steel I-beams and extremely thick plating. These feeders are typically driven electrically (through a vibratory gear box eccentric) and can be dumped directly onto by using OTR haul trucks and large-scale excavators. These style feeders are famous for scalping off large-scale boulders that will go directly into the rock crusher. Then, the pass-through material having been scalped off or sized down through the grizzly bar can go onto and up the overland conveyor beltline to the next process — which is usually screening and then secondary crushing.
Mid- to heavy-duty ranged feeders are often call apron feeders and can really take some abuse because they are built to handle it. These types of feeders can be stationary or portable. They can handle large amounts of productivity do to their slow but steady, massive steel chain conveying design. This type of feeder can be positioned under large dump hoppers or remain out in the open where one can pile on as much material as possible — being careful not to over-burden the next piece of process equipment beyond it. This style of feeder usually has a rubber belt running the entire length catching fine materials that leak through because of the steel-clad chain.
Another feeder is the dozer trap feeder and it is designed specifically for a large dozer to push material directly into it in one action. Dozer traps can be extremely efficient and easy to operate when applied into the correct operation of use.
Feeders for smaller-sized processed aggregates are reclaim tunnel feeders — used where large amounts of material reserves can be placed over them (since they are in a tunnel) and when operating, will continuously feed from those reserves requiring minimal feeding assistance from loaders/dozers. Reclaim tunnels offer a choice of a manual-lever clam gate (to meter material flow) with an automated air or hydraulic cylinder assist. Also, a short length conveyor or belt feeder is used to meter material through the roof openings.
Very unique vibratory plate feeders using electromagnetic forces for varying vibration (pan feeder) also operated as a manual eccentric v-belt driven style vibrator or even a reciprocating plate feeder positioned on wheels can be used to shuffle material under gravitational forces inside reclaim tunnel systems — or under individual free-standing surge hoppers. A 15 to 20-yard or 30 to 40 ton belt feeder is typically used for smaller-scale operations where blending products may be required or where productivity is not as constant or demanding. These hopper capacities are much less and require attention throughout the day to keep material processing further down the system.
Truck dump feeders are used to empty haul trucks. Some heavy-duty versions are capable of handling loads from mine-duty trucks and scrapers. However, these are just batch dump configured with minimal storage capacity and are designed for many cycles of dumps —therefore, they serve a much needed industry of remote location drop off points — typically for remote road repair based projects.
As you can see, this was a brief overview of the many types of feeders and their functions within the niche market of mining or aggregate materials production and material handling. Any of these feeders can crossover and be used in just about any other bulk material handling industry such as agricultural, recycling and even food processing.
If you enjoy these random aggregates and quarrying equipment-based subjects, tune back in for more topics to come. Send me a subject or topic you would like brought to light and any associated questions you would like to have discussed and I will gladly provide my best answer based upon my specific point of view and personal experience.
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Tim Holmberg / 2915 Idea Ave. / Aberdeen, SD 57401 n