Patent Publication Number: US-9903032-B2

Title: Aquatic metal ion harvesting device and system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of PCT/US2014/025550 filed 16 Jun. 2014 under 35 U.S.C. § 371 and the filing date of provisional patent application Ser. No. 61/781,453 filed Mar. 14, 2013 from which the PCT application claims priority. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON COMPACT DISC 
     None 
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention relates to devices used for extracting heavy metal ions from aqueous solutions. Specifically, devices able to extract and/or harvest heavy metal ions utilizing a defined electrical potential that may be deployed in large bodies of salt or fresh water. 
     (2) Description of Related Art 
     Over 70% of the surface of the earth is covered with water. It is estimated that there are over 321 billion cubic miles of water in the ocean. This water contains a proportional amount of metal ions distributed in varying concentrations throughout the world. For precious metals such as gold and platinum their concentrations can range from about 5 parts per trillion (ppt) to about 50 ppt. This translates to approximately 5 to 50 kilograms per cubic kilometer of ocean water. This makes the ocean one of the largest storehouses of precious metals such as gold in the world. 
     However, the ability to screen such large volumes of ocean water to extract sufficient gold to make the process profitable has been the greatest hurdle. Today, with the value of gold increasing and new innovations in precious metal extraction, the cost to screen large volumes of ocean water may reach the break-even point in the near future. Consequently, there is a need for a device that can efficiently harvest gold metal ions from large volumes of ocean water at low cost. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a device for recovering metal ions from bodies of water comprising two electrode cylinders, a keel, at least two connectors, a buoyant housing and a power supply. The first electrode cylinder comprises a front end, a top, a bottom, an exterior surface and a longitudinal axis. The second electrode cylinder is affixed within the first electrode cylinder by a bracket. The keel is affixed to the bottom of the exterior surface along the longitudinal axis of the first electrode cylinder. There are least two connectors affixed to the top along the longitudinal axis of the first electrode cylinder. The buoyant housing comprises an underwater surface and has at least one cable affixed to the underwater surface able to receive at least two connectors of the first electrode. The power supply may be affixed within the buoyant housing and provides variable voltage to the first and second electrode cylinders. 
     The power supply comprises a DC energy source, a rectifier circuit, a voltage regulator circuit, and a controller. The rectifier circuit has an input and output connection. The DC energy source is connected to the rectifier input. The voltage regulator circuit has an input and first and second outputs. The voltage regulator circuit input is connected to the rectifier circuit output. The voltage regulator circuit has an input and first and second outputs. The voltage regulator circuit input is connected to the rectifier circuit output. The first voltage regulator circuit output provides plating voltage to the second electrode plating cylinder and a sampling voltage. The sampling voltage and the plating voltage being unequal. The controller comprises a microprocessor, a memory means, switching means, a timing means and a monitoring means. The monitoring means comprises a first input and a second input. The first monitoring means input is connected to the second output of the voltage regulator circuit. The second monitoring means input receives electrical signals from the first electrode cylinder. The monitoring means periodically samples the signals to determine whether a current is drawn across the first and second electrode cylinders by the aqueous solution. The current is measured by the application of a sampling voltage to one of the electrodes. The electrical signal generated is converted into digital input signals readable by the microprocessor. The means for converting then converts the digital output signals generated by the microprocessor into an analog output signal for controlling the variable voltage. 
     The first electrode cylinder may further comprise a mesh covering the front end. In addition, the second electrode cylinder may be removably affixed within the first electrode cylinder. 
     The buoyant housing may further comprise one or more ballast tanks, one or more thrusters connected to the controller, wherein the thrusters are positioned on the underwater surface, or a pump wherein the pump is connected to the controller and in fluid connection with one or more ballast tanks. 
     In one embodiment the monitoring circuit includes means for substantially continuously measuring said current and comparing the current to a predetermined current threshold during application of the plating voltage. 
     In a second embodiment the controller comprises means for monitoring at least two of a plurality of parameters comprising current, the variable voltage, the predetermined current threshold and a predetermined voltage threshold sequentially in a continuous stream. Further the controller may comprise a display circuit for indicating the at least two parameters or a global positioning means able to activate one or more thrusters to control the positioning of the device. In addition, the controller may be operated remotely. 
     In a third embodiment the analog output signal is responsive to the substantially continuous measuring means such that adjustments in the analog output signal occur at the same frequency as measuring by the substantially continuous measuring means. 
     In a fourth embodiment the DC energy source may be a battery connected to at least one solar panel or at least one piezoelectric strip. 
     Other aspects of the invention are found throughout the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cross sectional view of an exemplary harvesting device of the present invention. 
         FIG. 2  is a front-end view of the exemplary harvesting device in  FIG. 1 . 
         FIG. 3  shows a top view and a side view of an exemplary self-contained free floating aquatic metal ion harvesting system containing one or more of the harvesting devices of  FIGS. 1 and 2 . 
         FIG. 4  is a schematic electric circuit diagram of one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Unless defined otherwise, all terms used herein have the same meaning as are commonly understood by one of skill in the art to which this invention belongs. All patents, patent applications and publications referred to throughout the disclosure herein are incorporated by reference in their entirety. In the event that there is a plurality of definitions for a term herein, those in this section prevail. 
     1. Method for Harvesting Metal Ions from Solution 
     A variety of methods are known in the art for extracting heavy metal ions, such as gold from an aqueous solution. U.S. Pat. No. 5,102,513 discloses one of these methods incorporated herein in its entirety. This system comprises a microprocessor that constantly monitors the actual voltage, actual current, preset voltage and preset current at the electrodes of the plating system. The microprocessor makes adjustments to maintain the voltage at a preset level by outputting a digital signal to a digital-to-analog converter which changes the digital command into a voltage which is used to adjust an output transistor which controls the voltage to the electrodes. This system applies digital technology for rapid sampling and response for providing a smooth output waveform to apply constant plating voltage as desired. 
     2. Harvesting Device 
     One aspect of the present invention is a device  210  for recovering metal ions from bodies of water comprising two electrode cylinders able to be connected to a power supply, a keel and at least two connectors.  FIG. 1  shows one example of an aquatic metal ion-harvesting device of the present invention. The device generally includes first and second electrodes, a keel and at least two connectors. The first electrode cylinder  201  comprises a front-end bracket  208 , a back end bracket  206 , a top, a bottom, an exterior surface  203  and a longitudinal axis. The second electrode cylinder  202  is affixed within the first electrode cylinder by brackets  206  and  208 . The keel  204 , that may be weighted  205 , is affixed to the bottom of the exterior surface along the longitudinal axis of the first electrode cylinder. At least one connector  214  is affixed to the top along the longitudinal axis of the first electrode cylinder. The device may further comprise a mesh  209  that acts as a protective grill for the first and second electrode cylinders. Power to the first electrode is supplied through wire  211  and wire  210  affixed to the second electrode cylinder  202  provides electrical connection to the second electrode. The aquatic metal ion-harvesting device is towable or suspendable in water by connectors  214 .  FIG. 2 , shows the front of the aquatic metal ion-harvesting device in  FIG. 1 . 
     3. Harvesting System 
     A second aspect of the present invention is a system for recovering metal ions from bodies of water comprising one or more of the devices described above connected to a buoyant housing. The buoyant housing comprises a DC energy source, a rectifier circuit, a voltage regulator circuit, and a controller. The rectifier circuit has an input and output connection. The DC energy source is connected to the rectifier input. The voltage regulator circuit has an input and first and second outputs. The voltage regulator circuit input is connected to the rectifier circuit output. The first voltage regulator circuit output provides plating voltage to the second electrode plating cylinder and a sampling voltage. The sampling voltage and the plating voltage being unequal. The controller comprises a microprocessor, a memory means, switching means, a timing means and a monitoring means. The monitoring means comprises a first input and a second input. The first monitoring means input is connected to the second output of the voltage regulator circuit. The second monitoring means input receives electrical signals from the first electrode cylinder. The monitoring means periodically samples the signals to determine whether a current is drawn across the first and second electrode cylinders by the aqueous solution. The current is measured by the application of a sampling voltage to one of the electrodes. The electrical signal generated is converted into digital input signals readable by the microprocessor. The means for converting then converts the digital output signals generated by the microprocessor into an analog output signal for controlling the variable voltage. 
       FIG. 3 , shows a top view and side view of an example of one aquatic metal ion-harvesting system of the present invention. The system generally comprises a buoyant housing  102  containing an energy storage means  103 , a renewable energy-harvesting source, one or more ballast tanks  105 , one or more thrusters  107  and one or more pumps  106 . The renewable energy source may include solar panels  101 , and/or piezo electric strips  108  to supply power to energy storage means  103  that may be one or more recharge batteries. The system controller  104 , may have a wireless connection  112  for remote control and data transfer, a camera  110  with light  111  may also be housed on top of said vessel under a clear protective dome  113 . The system is mobile, positioned by thrusters  107 , submerged and resurfaced by controlling ballast tanks  105 , driven by pump  106 . The side view of the aquatic metal ion-harvesting system in  FIG. 3  shows one or more aquatic metal ion harvesting devices  109  shown in  FIGS. 1 and 2 . 
     Referring to  FIG. 4 , which shows a detailed embodiment of the power supply, a microprocessor  40  is adapted to control the output voltage, display of output voltage and current, and regulation functions of the power supply. Microprocessor  40  operates in accordance with software instructions stored in an erasable programmable read-only memory (EPROM)  42 . Software instructions are retrieved and stored in a temporary memory latch  44  from which they are passed to microprocessor  40  in a manner well-known in the art. Microprocessor  40  operates at a 3.579 MHz clock rate, which is established by a clock circuit comprising a crystal  46 , and the two capacitors  47  and  48 . 
     Microprocessor  40 , operating under stored program control, monitors the four circuit parameters comprising actual output voltage, actual output current, preset reference voltage, and preset reference current. The preset reference voltage is established by adjusting variable resistor  49  while monitoring the appropriate test point. The preset reference current is established by adjusting resistor  51  while monitoring the appropriate test point (not shown). These four parameters are continuously and sequentially sampled by a quad switch  52 . Switch SW 1  is a double pole double throw momentary switch which permits the operator to substitute preset reference voltage and current for actual output voltage and current into quad switch  52 . When SW 1  is in its momentary position, the preset reference voltage is provided to the first and third inputs to quad switch  52  and the preset reference current is provided to the second and fourth inputs to quad switch  52 . Microprocessor  40  causes quad switch  52  to sequentially step through the four measurements by means of four control lines from microprocessor  40  to quad switch  52 . 
     Thus, microprocessor  40  raises the first sample line while holding the other three sample lines down. Quad switch  52  then connects the selected analog variable of the input to an analog-to-digital (A/D) converter  41 . A/D converter  41  then converts the selected analog variable to a single word, comprising eight bits, which is then passed to microprocessor  40 . After the analog sample has settled and the output of A/D converter  41  has stabilized, microprocessor  40  then drops the first sample line and raises the second sample line. This causes quad switch  52  to connect the next analog variable to A/D converter  41 . This process continues sequentially through the four analog variables and then restarts. The sampling of each parameter is substantially continuous in that any delay between subsequent readings of the same parameter is only the switching time to step through the other three parameters. 
     After each analog variable is sampled and read, microprocessor  40  makes adjustments to the output voltage as necessary to keep it equal to the preset reference voltage by computing an error level and passing a three-bit byte error value to a digital-to-analog (D/A) converter  43 . D/A converter  43  converts the three-bit error value into an analog error signal by selectably connecting the eight individual resistors  31  through  37  to ground through individual diodes  71  through  78  as shown. The sensitivity of this error signal is established by adjusting resistor  25  while monitoring the analog error signal voltage on an appropriate test point (not shown). 
     This analog error signal is passed to operational amplifier  64 , which serves to isolate the output voltage control circuit from the digital-to-analog conversion circuit. The output from op amp  64  is passed through series resistor  63  to the base of a Darlington transistor-pair, comprising driver transistor  62  and output transistor  61 , whereby output transistor  61  is biased to correct the error in the actual output voltage. The Darlington transistor-pair  62  and  61  acts as a series voltage regulator in the manner well-known in the art. 
     Microprocessor  40  also monitors the actual output current and displays both the output current and output voltage using a three-digit digital display comprising a display driver  150  and three seven-segment display chips  53  through  55 . Microprocessor  40  first convert the actual output voltage to a series of four-bit words corresponding to the three decimal display digits and passes these four-bit words in sequence to display driver  150 . Three of the four control lines between microprocessor  40  and quad switch  52  discussed above are used to multiplex the three seven-segment display chips  53  through  55 . A fifth control line from microprocessor  40  selects one of two LED diode indicators  57  and  58 . This multiplexing and indicator selection process requires a plurality of inverters which are provided by a multiple inverter chip  149 . (The inverters are indicated by reference numerals  59  and  149  due to their location in the schematic. All inverters may physically be on the same chip.) 
     The multiplex control signals to display chips  53  through  55  are passed through three inverters contained in chips  59  and  149 . Two more inverters from chip  149  are configured so that diode  57  is illuminated when a selection signal from pin  17  of microprocessor  40  is low and diode  58  is illuminated when the pin  17  selection signal is high. This pin  17  selection signal alternates every four seconds and is synchronized with the alternation of output voltage and output current data on the four-bit data bus from microprocessor  40  to display driver  150   
     The digital data at display driver  150  is decoded and sent to display chips  53 ,  54  and  55 . The three multiplex lines from microprocessor  40  step across display chips  53  through  55  every few milliseconds in synchronization with the shifting of display digit data from microprocessor  40 . Thus, within the four-second period for the display of a single parameter, microprocessor  40 , rapidly switches from the most significant digit (MSD) through the middle digit to the least significant digit (LSD) of the three-digit display. The multiplexing lines are synchronized with this shift in data in a well-known manner such that the three-digit display is driven by a single display driver ( 150 ) in a flicker-free display. At the end of the first four-second period, the control line at pin  17  of microprocessor  40  logically shifts and the same process occurs for the other display variable. The result of this circuit is a four-second display of actual output voltage accompanied with a lighted indicator  58 , following by a four-second display of actual output current accompanied by a lighted LED indicator  57 . This process continues indefinitely. 
     When the plating operation is active, a LED  158  is illuminated by means of a driver circuit comprising transistor  159  and resistors  160  and  161 . When the power supply is not able to raise actual output levels to match the preset parameters for voltage and current, a lockout circuit comprising transistor  66  and diode  67  is engaged. This lockout circuit forces the voltage at the base of the Darlington pair  61  and  62  to within two diode voltage drops of ground, thereby effectively interrupting the output of the power supply. 
     The lockout condition is initiated by microprocessor  40  when it raises the voltage on pin  16  in response to software interpretation of actual output voltage and current values. A voltage on pin  16  turns on transistor  141  through base resistor  140  and transistor  66  through base resistor  168 . Turning on  141  activates a piezoelectric sonic alarm  142  and illuminates lockout indicator diode  143  through resistor  144 . The voltage on pin  16  is inverted by inverter  86  and applied to the base of transistor  159 , which turns transistor  159  off. The conduction of transistor  66  forces the voltage at the base of transistor  62  down to a low value, which effectively turns off output transistor  61 . With the output transistor  61  turned off, no output current exists at the power supply output electrodes  80  and  82 . Microprocessor  40 , under stored program control, attempts to reset the lockout condition by reactivating the power supply circuit after four seconds and remeasuring the output voltage and current conditions. 
     The logical components described above receive their +5 volts DC power from a five-volt regulator chip  20 . A fuse  4  is provided in the primary AC side of center-tapped transformer  8  to protect the transformer from short-circuit currents. Transformer  8 , with the center-tapped primary and secondary windings connected as shown, and full wave rectifier bridge  10 , together with smoothing capacitor  11 , provide an unregulated DC supply voltage of 25 volts. Series resistor  12  and output transistor  61  control the current flowing at the output in accordance with the control signals developed in the remainder of the circuitry as described above. Capacitors  95 ,  96 ,  97  and  98  provide local filtering of noise pulses on the 5 volt DC supply in a well-known manner. 
     The information set forth above is provided to give those of ordinary skill in the art a complete disclosure and description of how to make and use the embodiments of the device and methods, and are not intended to limit the scope of what the inventor regards as his invention. Modifications of the above-described modes (for carrying out the invention that are obvious to persons of skill in the art) are intended to be within the scope of the following claims. All publications, patents, and patent applications cited in this specification are incorporated herein by reference.