The present invention relates to mining. More particularly, embodiments of the present invention provide methods and apparatus for locating and then detecting non-ferrous metal behind the wall of an underground mine.
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According to the website Goldsheetlinks, the annual world-wide production of gold exceeded 2,500 metric tons in 2010. Over the past year, the price of one ounce of gold has fallen from $1,800 to around $1,300. Meanwhile, the cost of producing an ounce of gold has been increasing for many mining operations. In June of 2013, when the price of gold dropped under $1,200 per ounce, the price exceeded the cost of production for some miners. The average cost of producing gold in Australia has nearly doubled over the past six years, rising from $500 to over $1,000 per ounce from 2007 to 2013.
The gold mining industry desperately requires a new system for producing gold at a lower cost. The development of a method and apparatus for producing gold at a reduced cost would constitute a major technological advance, and would satisfy long-felt needs in the gold and other precious metal extraction businesses.
The present invention comprises methods and apparatus for finding metal deposits in the Earth, and then determining whether these metal deposits are ferrous or non-ferrous.
One embodiment of the invention includes an Electromagnetic Quartz Penetrator. The Electromagnetic Quartz Penetrator includes a transmitter, a receiver, antennas and a first signal processor.
The Electromagnetic Quartz Penetrator is a portable device which is installed inside a mine, and is then aimed at an interior wall of the mine. The Electromagnetic Quartz Penetrator transmitter generates an Electromagnetic Plane Wave, which produces both an electric field and a first magnetic field. The electric field and the first magnetic field are mutually orthogonal. The Electromagnetic Plane Wave is directed at the interior wall of a mine by an antenna or by an antenna array. The area of the wall which is irradiated by Electromagnetic Plane Wave is generally a few feet wide and a few feet high.
The Electromagnetic Plane Wave travels deep into the Earth. In this embodiment, the Electromagnetic Plane Wave is useful to a depth ranging from zero to forty feet measured from the surface of the wall. The power of the Electromagnetic Plane Wave dissipates at a rate proportional to 1/r2.
The Electromagnetic Plane Wave penetrates a small three-dimensional volume of Earth which is adjacent to and lies immediately behind the area of the wall that is irradiated by the Electromagnetic Plane Wave.
The Electromagnetic Plane Wave finds deposits of metal within this volume of Earth behind the surface of the wall. The location of the metal deposits is determined by receiving waves which are reflected from the metal deposits, and by using the signal processor to interpret the received reflected waves. A graphical output is generated on a display that is read by the operator of the Quartz Penetrator. This graphical output provides the x, y and z coordinates of the metal deposit in a vein of quartz.
The present invention also includes an Omni-Directional H Field Metal Exciter and Sensor. The Omni-Directional H field exciter produces an output which has a spatial dissipation rate proportional to a factor of 1/r3, and, therefore, has a relatively short range compared to the Electromagnetic Plane Wave.
After the Electromagnetic Quartz Penetrator is used to determine the spatial coordinates of metal deposits behind the irradiated wall, a number of holes is drilled in the wall toward the location of the metal deposits. The Exciter is placed in a first hole, and then is activated. The Sensor is placed in a second hole. The Exciter produces a second magnetic field, which induces an eddy current in a metal deposit that has been found by the Electromagnetic Quartz Penetrator. The eddy current resembles a generally circular swirl of current around the metal deposit, and generates a return magnetic field. The Sensor detects the return magnetic field created by the eddy currents induced by the Exciter. A second signal processor, which is connected to the Sensor, interprets the signal collected by the Sensor.
If the induced eddy current in a metal deposit creates a return magnetic field in a very short interval of time, the metal deposit is known to be non-ferrous, and, therefore, probably contains gold.
If the induced eddy current in a metal deposit creates a return magnetic field over a relatively longer period of time, the metal deposit is know to be ferrous, and, therefore, does not contain gold. This method is also effective for identifying platinum and other precious non-ferrous metals.
The method and apparatus described in this embodiment of the invention may be used to accurately and reliably predict the location of gold in a quartz mine. This method and apparatus produces new and surprising successful results, and succeeds where previous mining methods have failed. The present invention lowers the cost of producing gold, and offers a great advantage to the gold mining industry.
An appreciation of the other aims and objectives of the present invention, and a more complete and comprehensive understanding of this invention, may be obtained by studying the following description of a preferred embodiment, and by referring to the accompanying drawings.
In this Specification, and in the Claims that follow, the term “mine” refers to any portion of the Earth, the Moon, or any other Celestial Body, whether exposed to the atmosphere, under a body of water, in space or underground, which is used to extract a mineral, an ore, an aggregate, a mixture or some other material or substance.
The term “metal” is a generally solid material at or near room temperature. Metals typically have high electrical conductivity, luster and malleability. Metals have electrons that are readily lost in chemical reactions with other substances. The Periodic Table currently includes 118 elements—91 of these are classified as metals.
The term “non-ferrous” refers to any metal or alloy that does not contain iron in appreciable amounts.
One embodiment of the invention utilizes an Electromagnetic Quartz Penetrator and an H-Field Exciter & Sensor. Both the Electromagnetic Quartz Penetrator and the H-Field Exciter & Sensor are contained in a control box. The control box is connected to a power supply (not shown) and transmit and receive antennas.
The transmit antenna of the Electromagnetic Quartz Penetrator irradiates a portion of a vertical wall inside the mine. The volume of Earth shown behind the wall contains a quartz vein. In one embodiment of the invention, the Electromagnetic Quartz Penetrator emits an Electromagnetic Plane Wave toward the vertical wall, and irradiates the volume of Earth behind it to a depth of about forty feet. When a deposit of metal is encountered, the metal reflects a signal back to receiving antenna. A signal processor connected to the receiving antenna interprets this reflected signal, and identifies the deposit as bearing metal. The signal processor also determines the location coordinates within the irradiated volume of Earth, and then are graphically depicted on a display. These coordinates may be displayed as Cartesian coordinates x, y and z; or as Polar coordinates r, Θ; or as any other suitable mathematical means of providing the spatial location of the metal deposit.
The Electromagnetic Plane Wave is designed to travel deep into the Earth behind the vertical wall. The power of the Electromagnetic Plane Wave falls by a factor of 1/r2. In recent experiments which are described in Section II of this Specification, the Electromagnetic Plane Wave is useful up to depths of about forty feet.
a+bi=c where i2=−1 Equation One.
k=r(cos θ)+i(sin θ) Equation Two.
In one embodiment of the invention, both the energy reflected from the deposit of metal may be resolved into real and imaginary components, and these two components may be used to verify the deposit as bearing metal. The real and imaginary components may also be used to determine the location of the metal deposit in the irradiated area.
After the Electromagnetic Plane Wave has been used to locate a deposit of metal, one or more holes are drilled in the wall, as shown in
In one experiment conducted in 2013, the present invention found and identified gold deposits 85 percent of the time. This compares favorably to the industry standard success rate of 5 percent.
In the experiment, holes were drilled using a AMT Air Leg Rock Drill Model No. IMT-104-W. A 3D Radar Geotech MK IV was used to propagate an Electromagnetic Plane Wave. A White Electronics MXT Pro along with a Sunray Invader DX-1 probe modified to have a 20 foot extension cable was used to propagate an H Field.