Patent Application
20180290903
Embodiments of the present invention relate generally to renewable energy and water recycling, and specifically, to an integrated system for supplying clean water and clean energy to the mining industry.
The global mining industry faces increasing scrutiny from government stakeholders, local communities and investors over compliance with increasingly stringent environmental regulations. In particular, large-scale mine developments are typically associated with significant energy and water consumption requirements in order to economically extract ore from native rock and reduce the extracted ore to a high value concentrate for mineral extraction. For example, energy-intense mining processes include ore excavation, crushing, milling, and transportation. Water-intense mining processes include extraction of minerals that may be in the form of solids, such as coal, iron, sand, and gravel; liquids, such as crude petroleum; and gases, such as natural gas, crushing, screening, washing and flotation of mined materials. In 2010, the U.S. mining industry consumed 5.3 Billion gal/day of water, equivalent to over 1% of the nation's entire water withdrawals. Total mining withdrawals in 2010 were 39 percent more than in 2005.
With new mineral resources being discovered in increasingly remote regions, and with recent commodity price volatility, mine developers are placing renewed emphasis on innovative technologies to optimize project economics. Energy costs for mine development and operations vary widely, depending upon each mine's proximity to existing transmission infrastructure, industrial market energy prices, and the requirement for on-site backup generation to ensure operational reliability. With wind and solar energy currently among the cheapest sources of new generation technology, mining sector interest in harnessing renewable energy to power mine processes continues to grow.
One drawback of renewable energy sources is their intermittency. In particular, the seasonality and daily cycles of wind and solar resources may limit the reliability of various types of renewable energy sources without storage. Even during daylight hours, solar energy is intermittent due to clouds and atmospheric interference that can radically impact the output of energy from photovoltaic cells. Similarly, wind resources also have a high degree of sub-hourly, daily, and season variability. If renewable energy sources are to be deployed at scale, then mines will also require access to significant energy storage capacity in order to ensure a stable and predictable power supply. The utilization of pumped storage hydroelectricity, including the use of upper and lower reservoirs provides for reliable and dispatchable, and cost-effective energy storage for mining operations.
Furthermore, mines have relied upon a combination of surface and ground water to supply their operational needs. However, water shortages in certain locations have placed mines in direct competition with farmers and local communities. In some instances, the water shortages have forced mine operators to adopt more expensive and complex solutions, such as seawater treatment, or processed wastewater, or municipal sewage recycling to secure water for mine operations and to support the communities in which the mines operate. With population growth predicted to boost global water demand over 50% by 2050, mine-related water conflicts are anticipated to further intensify. In particular, water-related infrastructure now accounts for approximately 10% of mining capital costs, with this share being higher for the more remote regions.
As the foregoing illustrates, what is needed in the art are more effective techniques for supplying the water and energy requirements of mines.
One embodiment of the present invention sets forth an integrated system for processing ore feedstock and RO treatment. The integrated system includes a first subsystem that generates waste associated with processing the ore feedstock. In the integrated system, the waste includes contaminated water. The integrated system further includes a second subsystem that treats the contaminated water included in the waste to generate recycled water and transmits the recycled water to the first subsystem.
One advantage of the disclosed techniques is that the integrated system reduces the net cost and the environmental impact of operating a mine in several ways. In particular, the disclosed invention provides a technique for recycling waste water from mining processes, thereby reducing the amount of fresh sources of water used in the mining process. In addition, the environmental performance of these systems is improved by storing intermittently generated clean energy which may otherwise be curtailed or stored by other much more expensive means, and deploying stored hydraulic energy to drive the RO subsystem and generate energy for the mine operations. Furthermore, the integrated system utilizes shared inflow-outflow structures, electrical grid connections, pipelines, and ancillary buildings, reduced pumps in the RO process, thereby reducing the net capital cost of implementing each of the subsystems that comprises the integrated system.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
In the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention. However, it will be apparent to one of skill in the art that the present invention may be practiced without one or more of these specific details.
The power supply for integrated system 100 may be generated by an on-site or near-by clean energy source 160. The clean energy source 160 may include a wind farm, a solar farm, a geothermal plant and/or another type of clean energy source. In addition, the integrated system 100 is also connected to a regional electricity grid in order to draw power from other generation sources during periods of low demand and low price, returning energy to the grid when required. The grid 163 is a set of transformers, power lines, and substations that step up, carry, and step down electricity between power plants and transmit and distribute electricity to consumers. In various embodiments, the integrated system 100 operates as a power plant supplying electricity to the grid 163. In other embodiments, the integrated system 100 operates as a consumer drawing electricity from the grid 163. In yet another embodiment, a back-up generator 162 provides energy to the integrated system 100. The back-up generator 162 may include various types of diesel, gasoline, three-phase, and/or high cycle generators. The back-up generator 162 may be connected to the powerhouse 150 via the high voltage transmission interconnections 155.
Further, the power supply for integrated system 100 may be generated through a pumped storage subsystem comprising the lower reservoir 140, the upper reservoir 145, and a pump-turbine (not shown). In various embodiments, the pump-turbine pumps water from the lower reservoir 140 to the upper reservoir 145. In particular, the pump-turbine pressurizes the water to up to a threshold pressure value before releasing the pressurized water into a penstock coupling the lower reservoir 140 and the upper reservoir 145. In addition, the pump-turbine converts energy in water flowing down the coupling the lower reservoir 140 and the upper reservoir 145 into electrical energy via a motor-generator. In various embodiments, the pump-turbine is connected to a motor-generator via a shaft. The motor-generator includes a rotor connected to the shaft and a stator disposed about the rotor. Rotating the rotor generates a time-varying magnetic field produced between the rotor and the stator. The time-varying magnetic force produces an electric current in the stator. Accordingly, as the water flows through the pump-turbine, the kinetic energy in the seawater is converted into electricity that can be used to power the integrated system 100 and/or returned to the grid 163.
In various embodiments, the high voltage transmission interconnections 155 coordinate the flow of electricity from one or more of the clean energy source 160, the grid 163, and the back-up generator 162 to various other components within the integrated system 100. For example, the high voltage transmission interconnections 155 may facilitate the flow of electricity to a powerhouse 150 in integrated system 100. This electricity may power a pump-turbine (not shown) that pumps water from a lower reservoir 140 to an upper reservoir 145.
In some embodiments, the high voltage transmission interconnections 155 receive electricity from the clean energy source 160. For example, a wind farm may be located proximate to the integrated system 100. The wind farm may dispense electrical energy through the high voltage transmission interconnections 155 to the powerhouse 150. Additionally or alternatively, photovoltaic cells may generate electrical energy from sunlight. The electrical energy may be transmitted through the high voltage transmission interconnections 155 to the powerhouse 150 in order to supply electricity to the pump-turbine.
In various embodiments, the per-unit cost of electricity supplied by the grid 163 may depend of several variables including state and federal regulations, the instantaneous conditions of various transmission and distribution systems, the conditions of each power plant, and the per-unit cost of fuel required by the integrated system 100. Accordingly, the per-unit cost of electricity may vary throughout a given period of time, such as a day or throughout a year. In some embodiments, the integrated system 100 is configured to draw electricity from the clean energy source 160 when the per-unit cost of electricity is low. In addition, the integrated system 100 may return electricity to the grid 163 when the per-unit cost of electricity is high, thereby resulting in a net profit.
In various embodiments, the lower reservoir 140 receives fresh water from a make-up fresh water supply. The make-up fresh water supply replaces water leaving the lower reservoir 140 in order to ensure that a threshold amount of water remains in the lower reservoir 140. In addition, the RO subsystem 120 supplies fresh water to the lower reservoir 140. The lower reservoir 140 supplies fresh water to the mine operation subsystem 130 and the tailrace 165. The tailrace 165 facilitates the flow of fresh water from the lower reservoir 140 to the powerhouse 150. The pump-turbines may pump the fresh water in the tailrace through the penstock 180 to the upper reservoir 145.
In various embodiments, the upper reservoir 145 stores water at an elevated location above the lower reservoir 140. For example, the upper reservoir 145 may be located 10 to 1,000 meters above the lower reservoir 140. In particular, the upper reservoir 145 may be located 200-400 meters or more above the mine operation subsystem 130. Elevating water from the lower reservoir 140 to the upper reservoir stores potential energy in the integrated system 100 in the form of gravitational potential energy. The potential energy can be harvested by allowing the water to flow from the upper reservoir 145 back to the lower reservoir 140. In particular, the potential energy stored in the water is converted to kinetic energy, which can be harvested by the pump-turbine. In various embodiments, the size and elevation of the upper reservoir 145 may be determined based on the output energy requirements of the integrated system 100. In particular, increasing the elevation of the upper reservoir 145 may increase the amount of power that can be generated by the integrated system 100. In addition, increasing the size of the upper reservoir 100 may increase the power generation uptime of the integrated system 100.
In various embodiments, the upper reservoir 145 and the lower reservoir 140 are lined with a non-permeable membrane that inhibits water from seeping through the bases of the upper reservoir 145 and lower reservoir 140 into the surrounding environment. The non-permeable membrane may include geotextile fabrics, reinforced polypropylene, and so forth. In some embodiments, the upper reservoir 145 and the lower reservoir 140 may also be sealed to limit environmental factors from interacting with water in the upper reservoir 145. For example, sealing the upper reservoir 145 and lower reservoir 140 may reduce water loss due to evaporation and protect the upper reservoir 145 and the lower reservoir 140 from debris. The sealing may be constructed out of various types of reinforce polypropylene fabrics and/or other types of materials. In other embodiments, the upper reservoir 145 and the lower reservoir 140 may remain unsealed. Accordingly, the make-up water supply may replace water loss due to evaporation and one or more meshes may be included in the tailrace 165 to filter out debris.
The penstock 180 is a water conveyance pipeline that facilitates the flow of water between the powerhouse 150 and the upper reservoir 145. In addition, the penstock 180 facilitates the flow of water from the powerhouse 150 to the RO subsystem 120. The penstock 180 may be constructed out of various types of materials, such as metals, alloys, and so forth. The thickness of the penstock 180 may vary along the length of the penstock 180. For example, the penstock 180 may be thicker at the base of the penstock 180 and thinner at the top of the penstock 180. In particular, the thickness of the penstock 180 may be determined based on an expected amount of force applied by the water on the penstock 180. For example, the penstock 180 may be constructed out of multiple pieces attached to one another. Each piece may further have a different thickness and/or strength rating.
In some embodiments, the penstock 180 may be constructed out of fiber-reinforced plastics to reduce corrosion from water and to reduce biofouling (e.g., adhesion of algae to the inner walls of the penstock 180). In addition, the penstock 180 may include antifouling coatings to reduce the build-up of materials on the inner surface of the penstock 180, in addition to anti-corrosion coatings. Using antifouling coatings and anti-corrosion materials may reduce the upkeep costs of maintaining the penstock 180, while also extending the lifetime of a penstock 180.
In various embodiments, the pump-turbine pumps water through the penstock 180 and into the upper reservoir 145. In particular, the pump-turbine pressurizes the water to up to a threshold pressure value before releasing the water into the penstock 180. In addition, the pump-turbine converts energy in the water flowing down the penstock 180 into electrical energy via a motor-generator. In various embodiments, the pump-turbine is connected to a motor-generator via a shaft. The motor-generator includes a rotor connected to the shaft and a stator disposed about the rotor. Rotating the rotor generates a time-varying magnetic field produced between the rotor and the stator. The time-varying magnetic force produces an electric current in the stator. Accordingly, as the water rotates the blades of the pump-turbine, the kinetic energy of the water is converted into electricity that may be transmitted to the grid 163.
In some embodiments, the pump-turbine may be constructed out of stainless steel. The stainless steel may be coated to protect against corrosion from contact with water and to reduce biofouling on the blades of the pump-turbines. In various embodiments, each penstock 180 may be connected to one or more pump-turbines. Additionally or alternatively, each pump-turbine may be connected to one or more penstocks 180.
In various embodiments, the penstock 180 includes a T-piece (not shown) that regulates the flow of water in the penstock 180 to the RO treatment subsystem 120. The operation of the RO treatment subsystem 120 is discussed in detail below.
The mine operation subsystem 130 includes the ore processing plant 170, the tailings pond 175, and the waste tank 190. The mine operation subsystem 130 facilitates the processing of mine ore. In particular, the ore processing plant 170 processes ore feedstock from a mining operation and separates the ore feedstock into mineral-bearing concentrate and waste. The water from the waste is released into a tailings pond 175 and is further released to the RO treatment subsystem 120 for filtration.
In various embodiments, the ore processing plant 170 receives water from the lower reservoir 140. The water supply from the lower reservoir 140 may facilitate the ore processing plant 170 in conducting extraction of mineral-bearing concentrate from ore feedstock. In particular, the ore processing plant 170 extracts concentrate via standard mining industry processes, including crushing, milling, and washing processes. The ore processing plant 170 discharges waste that may include spent ore and waste water. The waste is released to a thickener. In the thickener, the waste water is separated from the spent ore and is released to the RO treatment subsystem 120, while the remaining spent ore is released to a waste tank 190.
In various embodiments, the ore processing plant 170 may receive a steady-state flow of water or an intermitted supply of water from the lower reservoir 140. In addition, the ore processing plant 170 receives power from the clean energy source 160, the grid 163, and/or the back-up generator 162. The ore processing plant 170 further receives ore feedstock from mining operations occurring proximate to the integrated system 100.
The RO subsystem 120 uses reverse osmosis to generate potable drinking water from highly polluted water (e.g., waste water from the mining operation). In particular, the RO treatment subsystem 120 includes an energy recovery turbocharger (not shown) and a RO unit (not shown) that includes one or more ion-selective membranes. In various embodiments, the RO treatment subsystem 120 shares the waste tank 190 with the mining operation subsystem 130. In other embodiments, waste from the RO treatment subsystem 120 is processed by the ore processing plant 170 to further extract any mineral-bearing concentrate in the waste.
In operation, waste water from the mining operation subsystem 130 is released into the RO treatment subsystem 120 via the tailings pond 175. When the water enters the RO treatment subsystem 120, the water passes through one or more filters to remove small debris. Further, the water enters a set of energy recovery turbochargers that pressurizes the water to 700 psi or more. The filtered water is further released into the RO unit. In the RO unit, the water passes through ion-selective membranes that remove particulates from the filtered water to produce potable water. In various embodiments, the potable water flows out of the RO unit into the mine operation subsystem 130 and/or the lower reservoir 140, while the RO waste water is released into the waste tank 190.
In particular, the RO waste water outputted from the RO unit is highly pressurized. Accordingly, the RO waste water passes through an energy recovery turbocharger that captures embedded energy in the waste water discharge flows. The depressurized waste water is released to a waste tank 190. In various embodiments, the energy recovery turbocharger includes a pressure exchanger that captures the pressure energy of the pressurized waste water and uses that pressure to pressurize filtered water entering the energy recovery turbocharger. Accordingly, less energy is needed to pressurize the filtered water in the energy recovery turbocharger.
Furthermore, fresh water flowing down the penstock 180 may also be diverted into the RO treatment system via a T-piece. Instead of entering filtration, the water may enter a second energy recovery turbocharger. The second energy recovery turbocharger may include a pressure exchanger that captures the kinetic energy in the fresh water and uses that kinetic energy to pressurize filtered water entering the RO unit. The fresh water may further be released into the mine operation subsystem 130 and/or the lower reservoir 140, while the pressurized filtered water enters the RO unit.
The integrated system 100 operates in various operational cycles. In particular, the integrated system 100 may operate in a charging cycle, a generation cycle, and an idle cycle. Each operational cycle corresponds to a different stage of a clean energy storage and generation cycle. In particular, in the charging cycle, the integrated system 100 draws energy from the clean energy source 160, the grid 163, etc., in order to pump water from the lower reservoir 140 to the upper reservoir 145. The charging cycle enables hydraulic storage of energy. In the generation cycle, water flows from the upper reservoir 145 to the lower reservoir 140. A pump-turbine converts the kinetic energy of the water into electricity that can be supplied to the grid 163. Finally, in the idle cycle, the integrated system 100 neither elevates water from the lower reservoir 140 to the upper reservoir 145 nor allows water to flow from the upper reservoir 145 to the lower reservoir 140. Accordingly, electricity is not drawn from the clean energy source 160 to power the pump-turbines and the integrated system 100 does not supply power to the grid 163.
As discussed above, the integrated system 100 also includes the RO treatment subsystem 120. In particular, during the generation cycle, fresh water flowing down the penstock may be diverted into the RO treatment subsystem 120. The fresh water may pass through an energy recovery turbocharger that includes a pressure exchanger for capturing the kinetic energy of the fresh water. The fresh water may further be released into the lower reservoir 140. In various embodiments, the RO treatment subsystem 120 may continuously or intermittently operate during any of the generating cycles, the charging cycles, and the idle cycles. Similarly, the mine operation subsystem 130 may continuously or intermittently operation during any of the above cycles, as well.
In various embodiments, a local clean energy source 160 may be constructed proximate to the integrated system 100. For example, a wind farm, a solar farm may be constructed proximate to the integrated system 100. The type of clean energy source 160 may be selected based on the regional availability of the associated energy source. For example, if strong winds are present, then a wind farm may be constructed on-site and/or nearby the integrate system 100. Similarly, if extended periods of sunlight with high radiation are present, then a solar farm may be constructed on-site and/or nearby the integrated system 100.
In embodiments that include the local clean energy source 160, during the charging cycle, the integrated system 100 may selectively draw power from the local clean energy source 160, the grid 163, the back-up generator 162, or some combination thereof. For example, when the local clean energy source 160 is generating power, the integrated system 100 may select to draw power from the local clean energy source 160. However, during periods of low power production by the local clean energy source 160, the integrated system 100 may draw power from the grid 163 and/or the back-up generator 162 to meet the energy requirements of various components of the integrated system 100.
In the charging cycle, the energy subsystem 110 draws energy from the clean energy source 160 in order to pump water from the lower reservoir 140 to the upper reservoir 145. The charging cycle enables hydraulic storage of energy from the clean energy source 160 in the energy subsystem 110. In various embodiments, fresh water flows from the lower reservoir 140 through a variable speed pump-turbine 290 to the penstock 180. The pump-turbine 290 operates as a pump: drawing water from the lower reservoir 140, pressurizing the water, and releasing the water into the penstock 180.
In various embodiments, the pump-turbine 290 is connected to a motor that rotates the blades of the pump-turbine 290. Electricity is supplied to the motor via the high voltage transmission interconnections 155. Rotating the blades of the pump-turbine 290 exerts a centripetal force on the water that pressurizes the water. The water that is released from the pump-turbine has at least a threshold pressure, sufficient to cause the water to travel up the penstock 180 to the upper reservoir 145. In other embodiments, the pump-turbine 290 may pressurize the water up to a higher or lower pressure value. For example, the pressure threshold may be between 300-600 psi. In various embodiments, the pressure threshold is selected based on the cross-sectional width and height of the penstock 180. In some embodiments, a variable speed pump-turbine 290 may be implemented. In such embodiments, by controlling the speed of the pump-turbine 290, the pressure of the water may be increased or decreased. Accordingly, the pump-turbine 290 may be configured to pressurize the water up to different pressure threshold values during the charging cycle.
The pressurized water is released from the pump-turbine 290 into the penstock 180. As discussed above, the T-piece 210 including a regulator is located at the base of the penstock 180. The regulator included in the T-piece 210 diverts pressurized water into the RO subsystem 120. In some embodiments, a penstock 180 may supply pressurized water to multiple RO treatment subsystems 120. In other embodiments, multiple penstocks 180 may supply pressurized water to a single RO treatment subsystem 120.
The pressurized water in the penstock 180 that is not diverted into the RO treatment subsystem 120 flows up the penstock 180 into an upper reservoir 145. The upper reservoir 145 is lined to prevent water from leaking into the surrounding area. The upper reservoir 145 stores the water throughout the charging cycle. In various embodiments, the upper reservoir 145 may be sized to store sufficient amounts of water to provide 10-1000 MW of hydroelectric power or more. In other embodiments, multiple upper reservoirs 145 may be implemented in conjunction. In addition, multiple penstocks 180 may supply water to a single upper reservoir 145 and/or a single penstock 180 may supply water to multiple upper reservoirs 145. Similarly, one or more lower reservoirs 140 may be implemented in various embodiments of the present invention.
In the generation cycle, water flows from the upper reservoir 145 into the lower reservoir 140. A pump-turbine 290 converts the kinetic energy of the water flowing through the penstock 180 into electricity that can be transmitted to the grid 163. In particular, the direction of rotation of the blades of the pump turbine is reversed from in the charging cycle in order to cause the pump-turbine 290 to operate as a turbine. As water flows through the pump-turbine 290, the water rotates the blades of the pump-turbine 290. The pump-turbine 290 is coupled to a motor-generator 295 in a manner that causes the motor-generator 295 to produce electricity as the pump-turbine 290 rotates. In particular, as the water flows down the penstock 180, the potential energy in the water is converted to kinetic energy. Accordingly, the kinetic energy of the water exerts a force on the blades of the pump-turbine 290, causing the pump-turbine 290 to rotate. Rotating the turbine rotates a rotor disposed within a stator of the motor-generator 295. In particular, rotating the rotor produces a time-varying magnetic field that produces an electric field in the motor-generator 295. Accordingly, the pump-turbine 290 coupled to the motor-generator 295 converts the kinetic energy of the water into electricity.
In the charging cycle and the generating cycle, the regulator included in the T-piece 210 may divert water from the penstock into the RO treatment subsystem 120. In particular, the regulator controls the flow of pressurized water from the penstock into the RO treatment subsystem 120. The pressurized water enters the energy recovery turbochargers 220 and the pressure energy of the water is harvested by pressure exchangers within the energy recovery turbochargers 220. The depressurized water is further released back into the lower reservoir 140.
In the idle cycle, the energy subsystem 110 neither pumps water from lower reservoir 140 to the upper reservoir 145 nor allows water the flow from the upper reservoir 145 through the pump-turbine 290. In particular, the pump-turbine 290 is shut off and water does not pass through the pump-turbine 290. In some embodiments, the energy subsystem 110 may transition to the generation cycle from either the charging cycle or the idle cycle with fast response times of less than 5 minutes.
In addition, the lower reservoir 140 provides water to the mine operation subsystem 130. In particular, the ore processing plant 170 may obtain water from the lower reservoir 140. In some embodiments, water is pumped from the lower reservoir 140 into the ore processing plant 170. Additionally or alternatively, the ore processing plant 170 may be located at an elevation below the lower reservoir 140 and a control value may regulate the flow of water into the ore processing plant 170.
Furthermore, power is supplied to the mine operation subsystem 130 via the energy subsystem 110. In particular, one or more of the grid 163, back-up generator 162, and the clean energy source 160 supplies electricity to the ore processing plant 170. The electricity may facilitate the ore processing plant 170 in preforming various operations in extracting mineral-bearing ore from ore feedstock.
In various embodiments, the upper reservoir 145 is sized to store 10 MW to 1,000 MW. For example, the upper reservoir 145 may be sized to store 300 megawatts of water. In other embodiments, multiple smaller upper reservoirs 145 may be utilized. Each upper reservoir 145 may be connected to separate penstocks 180. Each penstock 180 may have a cross-sectional width between 10 and 50 ft.
The filter module 230 receives waste water from the mine operation subsystem 130, including the thickener 310, the tailings storage 320, and the tailings pond 330. In various embodiments, the filter module 230 may conduct low pressure filtration of the waste water. In particular, in some embodiments, the waste water may flow at low pressure (i.e., 100 psi or less). The filter module 230 includes a series of increasingly fine filters that remove debris from the waste water passing through the filter module 230. For example, the filter module 230 may include strainers, filters and ultra-fine filters.
In addition, the filter module 230 may include chemical treatment and ultra-violent disinfection stages for processing the waste water. The chemical treatment process may include adding acids, caustics, dechlorination chemicals, and antiscalants and dispersants to the waste water. Acids may be used to reduce the pH of the waste water. Example acids may include sulfuric acid and hydrochloric acid. Additionally or alternatively, caustics may be used to increase the pH of the waste water. For example, sodium hydroxide may be introduced in the waste water to increase the pH of the waste water. Dechlorination chemicals may be used to remove free chlorine residual in the waste water. Removing free chlorine from the waste water may reduce the likelihood of oxidation damage on filtration membranes. In addition, antiscalants may be used to inhibit the formation and precipitation of crystallized mineral salts that may form in the waste water, while dispersants may be used to inhibit the agglomeration and deposition of foulants on filtration membranes. In addition, ultraviolet treatment may be used for sterilization of the waste water. For example, ultraviolet treatment may be used to kill algae and reduce algae deposit formation in the waste water.
In addition, the filter module 230 may include various types of chemicals that may stimulate secondary recovery of a dissolved target mineral resource. In particular, the waste may be processed by a secondary processing plant (not shown) and/or the ore processing plant 170 to reclaim the dissolved target mineral before the waste is released to the waste tank 190.
The filtered water exits the filter module 230 and flows through a pipeline into the energy recovery turbocharger 220. The energy recovery turbocharger 220 receives the filtered water and pressurizes the filtered water. The pressurized water is released to the RO unit 240. In some embodiments, the energy recovery turbocharger 220 increases the pressure of the water to 800 psi or more. For example, a pair of turbocharges may be implemented. The first turbocharger may pressurize the filtered water up to 400 psi and the second turbocharger may pressurize the filtered water from 400 psi to 800 psi.
For example, a first energy recovery turbocharger 220 may receive pressurized waste from the RO unit 240. The energy recovery turbocharger 220 passes the pressurized waste through a pressure exchanger. In one embodiment, the pressure exchanger includes a rotor that is physically connected to a shaft. The rotor converts the pressure energy of the water into mechanical rotational energy of the shaft. The shaft is further connected to a second rotor. When the pressurized waste flows through the pressure exchanger, the pressurized waste rotates the shaft, which causes the second rotor to rotate. The pressurized water flowing into the energy recovery turbocharger 220 passes through the second rotor that exerts a centripetal force on the water, thereby increasing the pressure of the filtered water flowing into the energy recovery turbocharger 220. Accordingly, the energy recovery turbocharger 220 uses a pressure exchanger to harvest the pressure of the pressurized waste to increase the pressure of pressurized water flowing into the energy recovery turbocharger 220.
For example, filtered water flowing out of the filter module 230 may have a pressure of 50 psi and the pressurized waste flowing out of the RO unit 240 may have a pressure of 500 psi. As the filtered water flows over the second rotor, the filtered water may be pressurized up to 450 psi. Similarly, as the pressurized waste flows through the first rotor, the pressurized waste may be depressurized to 20 psi. Accordingly, the pressure exchanger may reduce the amount of power required to increase the pressure of the filtered water to a threshold pressure value before the filtered water enters the RO unit 240.
Similarly, a second energy recovery turbocharger 220 may receive high kinetic energy fresh water flowing down the penstock 180. The kinetic energy of the water can generate water pressures of 400 psi or more. Accordingly, the fresh water flowing down the penstock will be herein referenced as pressurized water. In various embodiments, a T-piece 210 regulates the flow of pressurized water from the penstock 180 into the RO treatment subsystem 120. In particular, the second energy turbocharge may receive the pressurized water flowing into the RO treatment subsystem 120 and may harvest the pressure of the pressurized water to pressurize filtered water entering the RO unit 240, as described above.
In various embodiments, the T-piece 210 may be located at the base of the penstock 180. In addition, the T-piece 210 may be rated for various threshold water pressure values. For example, the T-piece 210 may be designed for water pressurized up to 600 psi or more. Other threshold values are within the scope of this invention. For example, the T-piece 210 may be rated for up to 700 psi. In particular, the T-piece 210 is designed to withstand a water pressure threshold that exceeds the pressure of water exiting the pump-turbine 290 and/or high kinetic energy water flowing down the penstock 180.
Furthermore, the T-piece 210 may include a regulator that controls the flow of water through the T-piece 210. The regulator diverts pressurized water into the RO treatment subsystem 120 at a particular flow rate, while the remainder of the pressurized water flows through the blades of the pump-turbine 290 and into the lower reservoir 140.
In addition, the energy recovery turbocharger 220 may include one or more additional pumps to further increase the pressure of the water flowing into the energy recovery turbocharger 220 up to a threshold pressure before releasing the pressurized water into the RO unit 240. For example, the additional pumps may further increase the pressure of the filtered water to up to 1000 psi or more.
In various embodiments, RO unit 240 may include one or more ion-selective membranes that filter out particulates from the pressurized water exiting the energy recovery turbocharger 220. The resulting fresh water permeate may be released to the mine operation subsystem 130. In particular, the ore processing plant 170 may use the fresh water in processing mineral-bearing concentrate from ore feedstock. In some embodiments, 40% of the water that flows into the RO unit 240 flows out of the RO unit 240 as fresh water permeate. In other embodiments, 20% to 60% of the water flowing into the RO unit 240 may be released as fresh water permeate. In addition, approximately 60% of the water flowing into the RO unit 240 may be released as waste concentrate. However, in other embodiments, 30% to 80% of the water flowing into the RO unit 240 may be released as waste concentrate. In various embodiments, the waste concentrate may exit the RO unit 240 at a similar pressure to the pressure of water flowing into the RO unit 240. For example, water may flow into the RO unit 240 at 800 psi and waste concentrate may flow out of the RO unit 240 between 700-800 psi.
After passing through the energy recovery turbocharger 220, the waste concentrate may enter a waste tank 190. In various embodiments, the waste tank 190 is sized to store 12-72 hours of waste concentrate outputted by the RO unit 240.
A T-piece 210 may be connected to the base of the penstock 180, above the pump-turbine 290. The regulator within the T-piece 210 may direct between 5-20% of pressurized water flowing down the penstock 180 into the RO subsystem 120. In some embodiments, each penstock 180 may be connected to a separate RO subsystem 120. In other embodiments, multiple penstocks 180 may connect to a single RO subsystem 120. In addition, a single penstock 180 may supply pressurized water to multiple RO subsystems 120.
In various embodiments, the ore processing plant 170 receives ore feedstock 410 from a local mine. The ore processing plant 170 receives power from the energy subsystem 110. In addition, the ore processing plant 170 receives fresh water from the lower reservoir 140 and filtered water from the RO unit 240. The ore processing plant 170 uses the water from the RO subsystem 120 and the water and power from the energy subsystem 110 to process the ore feedstock 410. In particular, the ore processing plant 170 performs a sequence of processing steps. For example, the ore processing plant 170 may perform energy intensive processing steps, including crushing, milling. In addition, the ore processing plant 170 may perform a sequence of water-intensive processing steps including screening, washing, and flotation of mined materials. The processing steps separate the mineral-bearing concentrate 420 from the spent ore. In various embodiments, the mineral-bearing concentrate 420 is released for further processing and the spent ore flows into the thickener 310.
In the thickener 310, the waste water is separated from the spent ore. Various types of thickeners 310 known in the field are within the scope of the invention. For example, a Dorr thickener 310 may be used to continuously separate waste water from solids in the spent ore. Additionally or alternatively, spent ore may be feed into a flat-bottom tank. The spent ore may be left undisturbed to allow particulates in the spent ore to separate from the waste water and settle at the bottom of the flat-bottom tanks. The waste water may be removed from the thickener 310 and pumped into the RO system 120. The remaining waste in the thickener 310 is released to the tailings storage 320.
The tailings storage 320 may include one or more semi-permeable filters and/or membranes that allow any remaining waste water to seep out of the tailings storage 320. The seepage is collected in a tailings pond 330 disposed below the tailings storage 320. The waste water may be pumped from the tailings pond 330 into the RO system. The solid waste stored in the tailing storage may further be removed by mine workers in an environmentally friendly manner that upholds local regulatory standards.
In various embodiments, the ore processing plant 170 may receive a steady-state flow of water or an intermittent supply of water from the lower reservoir 140. In addition, the ore processing plant 170 receives power from the clean energy source 160, the grid 163, and/or the back-up generator 162. The ore processing plant 170 further receives ore feedstock 410 from mining operations occurring proximate to the integrated system 100.
In various embodiments, the energy subsystem 110 provides the power supply for the integrated system 100. In particular, the energy subsystem 110 includes one or more power sources including a connection to the grid 163, a back-up generator 162, and a clean energy source 160. The clean energy source 160 provides electricity to the pump-turbine 290 and to the ore processing plant 170. In various embodiments, the clean energy source 160 also provides power to the RO treatment subsystem 120 to facilitate the RO treatment subsystem 120 in filtering waste water from the mine operation subsystem 130.
In various embodiments, the energy subsystem 110 also provides fresh water to the mine operation subsystem 130 and the RO subsystem 120. In particular, the lower reservoir 140 supplies fresh water to the ore processing plant 170. The fresh water facilitates the ore processing plant 170 in converting ore feedstock 410 into mineral-bearing concentrate 420. In addition, the lower reservoir 140 provides pressurized fresh water to the RO treatment subsystem 120. The pressurized fresh water is used by the energy recovery turbocharger 220 to pressurize filtered waste water entering the RO unit 240.
In sum, the disclosed integrated system includes an energy subsystem, a RO treatment subsystem, and a mine operation subsystem. The energy system may include clean energy sources, back-up generators, and connections to the grid. In addition, the energy subsystem stores hydraulic energy in an upper reservoir during a charging cycle, and converts that stored energy into electricity during a generation cycle. In addition, the energy subsystem exchanges water with the RO treatment subsystem and the mine operation subsystem. In particular, the RO treatment subsystem recycles waste water from the mine operation subsystem and releases the recycled water back into the mine operation subsystem. The mine operation subsystem performs various processing steps to isolate mineral-bearing concentrate from ore feedstock using energy and water from the energy subsystem and recycled water from the RO treatment subsystem.
Advantageously, the integrated system reduces the net cost and the environmental impact of operating a mine in several ways. In particular, the disclosed invention provides a technique for maximizing the proportion of mine waste water being recycled, thereby reducing the amount of water used in the mining process. In addition, the environmental performance of these systems is improved by storing intermittently generated clean energy which may otherwise be curtailed or stored by other much more expensive means, and deploying stored hydraulic energy to drive the RO treatment subsystem. Furthermore, the integrated system utilizes shared inflow-outflow structures, electrical grid connections, pipelines, and ancillary buildings, reduced pumps in the RO treatment process, thereby reducing the net capital cost of implementing each of the subsystems that comprises the integrated system.
1. In some embodiments, an integrated system for processing ore feedstock and reverse osmosis (RO) treatment comprises a first subsystem that generates waste associated with processing the ore feedstock, wherein the waste includes contaminated water, and a second subsystem that treats the contaminated water included in the waste to generate recycled water, and transmits the recycled water to the first subsystem.
2. The integrated system of clause 1, further comprising a third subsystem that provides clean energy to at least one of the first subsystem and the second subsystem.
3. The integrated system of clauses 1 or 2, wherein the first subsystem comprises an ore processing plant that processes ore feedstock to produce mineral-bearing concentrate.
4. The integrated system of any of clauses 1-3, wherein the first subsystem comprises one or more of a thickener and a tailings storage that store waste and separate contaminated water in the waste from spent ore.
5. The integrated system of any of clauses 1-4, wherein the contaminated water from the first subsystem is transmitted from the first subsystem to the second subsystem.
6. The integrated system of any of clauses 1-5, wherein the second subsystem includes a filter module that removes particulates from the contaminated water to produce filtered water.
7. The integrated system of any of clauses 1-6, wherein an energy recovery turbocharger pressurizes filtered water from the filter module and released the pressurized water to a RO unit.
8. The integrated system of any of clauses 1-7, wherein the RO unit passes the pressurized water through one or more ion selective filters to produce the recycled water.
9. The integrated system of any of clauses 1-8, wherein the RO unit further produces pressurized waste, and wherein the pressurized waste from the RO unit is released to the energy recovery turbocharger.
10. The integrated system of any of clauses 1-9, wherein the energy recovery turbocharger comprises a pressure exchanger, wherein the pressurized waste is depressurized by passing the pressurized waste through a first rotor of the pressure exchanger.
11. The integrated system of any of clauses 1-10, wherein the depressurized waste and the particulates from the filter module are processed to capture mineral-bearing concentrate.
12. The integrated system of any of clauses 1-11, wherein the filtered water from the filter module passes through a second rotor of the pressure exchanger that is connected to the first rotor by a shaft, wherein the filtered water is pressurized by the second rotor.
13. The integrated system of any of clauses 1-12, wherein the third subsystem further provides water to the first subsystem, wherein the first subsystem, during the processing of the ore feedstock, converts the water to the contaminated water.
14. The integrated system of any of clauses 1-13, wherein the third subsystem comprises at least one of a wind farm and a solar farm that generates electricity that is transmitted to at least one of the first subsystem, the second subsystem, and a grid.
15. The integrated system of any of clauses 1-14, wherein the third subsystem further provides pressurized water to the second subsystem, wherein the pressurized water enters a second energy recovery turbocharger that depressurizes the pressurized water and pressurizes filtered water from the filter module.
16. The integrated system of any of clauses 1-15, wherein the third subsystem further comprises a first reservoir that stores water, a second reservoir located above the first reservoir that also stores water, a penstock that connects the first reservoir to the second reservoir, and a pump-turbine that pumps water through the penstock from the first reservoir to the second reservoir.
17. The integrated system of any of clauses 1-16, wherein the pump-turbine is coupled to a motor-generator.
18. The integrated system of any of clauses 1-17, wherein, when water flows from the second reservoir to the first reservoir via the penstock, the water rotates the pump-turbine causing the motor-generator to generate electricity.
19. The integrated system of any of clauses 1-18, wherein the electricity generated by the motor-generator is released to a grid.
20. The integrated system of any of clauses 1-19, wherein a water supply provides water to the third subsystem.
21. The integrated system of any of clauses 1-20, wherein the third subsystem further comprises a clean energy source.
Any and all combinations of any of the claim elements recited in any of the claims and/or any elements described in this application, in any fashion, fall within the contemplated scope of the present invention and protection.
The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. While the preceding is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority benefit of the U.S. Provisional patent application titled, “SYSTEM INTEGRATING RENEWABLE ENERGY, SALT WATER PUMPED HYDROELECTRIC STORAGE, AND REVERSE OSMOSIS DESALINATION,” filed on Apr. 10, 2017 and having Ser. No. 62/483,879, this application also claims priority benefit of the U.S. Provisional patent application titled, “SYSTEM INTEGRATING RENEWABLE ENERGY, PUMPED HYDROELECTRIC STORAGE, AND REVERSE OSMOSIS DESALINATION FOR MINE DEVELOPMENT AND OPERATIONS,” filed on Jun. 1, 2017 and having Ser. No. 62/513,845. The subject matter of these related applications is hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62483879 | Apr 2017 | US | |
| 62513845 | Jun 2017 | US |
