Excavation #37
The reason for the conception of this art is the development of a new and improved device to move blast hole drill tailings back toward and down the drilled hole in a more efficient manner. The Backfill Attachment Device is a technology used to radically improve the process of backfilling blast holes in the strip mining process.
The machine described in U.S. Pat. No. 4,138,832 (inventor Carl Cooper, deceased) needed to be improved in several areas. The building of a complete vehicle to house and carry the machine proved to be impractical. The blade design of the singular arcuate blade needed improvement to increase earth excavating or moving capability. The need to develop a new system to recover the primer cord is necessary. The primer cord is a blasting cord that detonates the explosives in the blast hole. It has to be safely protected during the fill process and not lost down the hole. Recovering more dirt backfill is a problem needing to be addressed as well. Lastly, the ability to view the blast hole by the operator of the vehicle is essential.
The Backfill Attachment Device embraces several novel changes that addresses several issues and improves the utility of the original concept. The major new design concept will be a Backfill Attachment Device that will operate as an attachment adaptable to a vehicle possessing a self-contained hydraulic motion system. This vehicle will have an attachment capability (i.e. a Bobcat type vehicle).
The second issue we address is improving the dirt moving (drill tailings) arcuate blade design. The new blades are constructed with an outer cutting edge attached perpendicularly to the end of the blades and an L shaped edge added to the bottom of the blade.
Those in the strip mining business are aware of the need to stem or backfill blast holes after they are partially loaded with explosives. The blast holes loaded with explosives must have the balance of the hole backfilled with the drill tailings lying around the hole. This preserves the pressure and desired fracturing process caused by the ignition of the explosives in the hole.
The third design change is a new method of recovering the primer cord that is essential. With the operator driving the vehicle 6 or 8 feet away from the hole, a capability to recover and protect the integrity of the primer cord from a distance is needed. A electromagnet on a vertical guide allows the electromagnet to move up and down the central opening of the backfill device. A 4 inch by 2 inch thin flat unit of metal is attached to the end of the primer cord. The magnet is lowered into the central opening of the backfill device by an appropriate sized shaft. The electromagnet attracts and attaches to the 4×2 piece of aforementioned flat metal and is raised at least 12 inches clearing the moving blades.
The issue of pulling more dirt or drill tailings to the blast hole without making the overall backfill device too large required a change. A two piece curved blade surrounding the circular backfill device is necessary. The two curved blades are attached by four hydraulic cylinders to the top of the safety cover on the backfill device. These blades are designed to pull drill tailings beyond the reach of the Backfill Attachment Device's arcuate blades and into their range of motion to be picked up and pushed to the middle of the device to be deposited in the blast hole.
Lastly, to allow the operator a more precise view of where the blast hole is located, a closed circuit video camera is attached to the center of the backfill device. It is attached to allow the operator to view the blast hole via the open horizontal column at the center of the rotating arcuate blades. A small video monitor is placed in the cab of the vehicle so the operator can view where to situate the backfill device.
The following list is the description of the numbered parts on the drawings:
The Backfill Attachment Device is designed to improve the efficiency of backfilling blast holes drilled in the strip mining process. The overburden above the coal must be loosened in order to be removed. First, a grid of blast holes 40 feet or more are drilled that are approximately 1 foot in diameter. The drilled holes then are loaded with explosives and to retain the energy of the detonated explosives in the hole you must backfill the balance of the hole to the surface with the drill tailings. The explosives consist of a cast primer lowered to the bottom of the hole with a line of primer cord and then the hole is loaded with explosives. It is very important to protect the integrity of the primer cord. The holes are currently backfilled by picking up the drill tailings or soil with a loader and dumping the dirt in a dump truck. The drill tailings are then poured down each hole until full. The Backfill Attachment Device will speed up the process by pushing the tailings back down the blast hole from where they lie after the drilling process. This will greatly improve productivity by saving time.
The Backfill Attachment Device is attached to a vehicle similar to but not necessarily a Bobcat type vehicle. It is attached using the universal quick attachment device for utility attachments (part #21
Using the closed circuit camera (part#4) the machine is centered with the central opening (part #6) over the blast hole. The electromagnet (part#3) is lowered into the hole where it is charged and magnetically picks up the metal primer cord recovery piece (part#20) with attached primer cord. The metal primer cord recovery piece (part #20) is raised until visible to the operator showing the primer cord to be clear of the moving blades (part#9).
Each part of the machine is composed of the appropriate grade and thickness of steel. The excavating components are made of high carbon steel (parts #9, 10, 1). Steel tensile strength and overall weight and thickness are a factor in determining construction material.
With the hydraulic motor engaged (part#12) sprocket-1 (part#13) turns sprocket-2 (part#17) with connected power chain (part#14). This assembly turns the hollow rotating shaft (part#15), with attached rotary disc and attached arcuate blades (part#9), and the perpendicular cutting blades (part#10