Wastewater Treatment

Mill Feedwater Pressure Control

Success Story: Mill Feedwater Pressure Control Copper is a valuable metal used in many residential, commercial, and industrial products. From wiring and consumer electronics to HVAC systems to electrical vehicles, copper is an essential element necessary to produce such products. Copper mining is a complex process and water is its’ lifeblood. It allows for the separation and recovery of salable copper. Throughout the milling and flotation cell processed, over double the amount of water is required throughout the crush-grind-flotation-concentrate circuit. Poor control of the mine’s water supply can negatively impact process run-time, leading to constrained production levels and hurting the bottom line. Additionally, as a mine ages, copper ore grade generally decline. To maintain target recovery rates, mines must process more material called ore tons. As time passes this adds to the mine’s overall water consumption.  Around the world mining companies are working to develop a more sustainable production method to address environmental concerns and maintain stable operations. Chile is home to the world’s largest copper mine and it is the country’s largest water consumer. In 2018, the mine underwent an expansion project to implement a desalination plant and added a necessary pipeline to feed the operation. The goal was to operate entirely on desalinated water by the year 2030. In 2020, 10 years ahead of the planned schedule, that goal was achieved. The mine’s water source is pumped over 3,100 meters above sea level to a reservoir near the mine. From there, the water is then delivered through a 36-inch discharge line and is controlled with an 18-inch globe valve. The pond is the sole water supply to the mill andconcentrator.  Greater process control is the hallmark of REXA’s Electraulic™ Actuators. Our actuators are more precise and accurate in performance than pneumatics and more reliable than traditional hydraulic technologies. This mine’s location is remote, arid, and the ambient temperature can drop below 0°C in the winter. For this project, themine had considered pneumatic actuators. The decision was made to not use the pneumatics because of their marginal positioning accuracy and reliability. To keep the concentrator process running, it is crucial that there is water present. Mine operators chose to rely on REXA Electaulic™ Actuators as the final control element to control water flow rate and emergency shutoff. Upon an unexpected loss of power, the linear actuators, equipped with accumulator bottles, produce up to 20,000 lb (89,000 N) of thrust that can safely close the valves using pressurized nitrogen.  In 2021, desalinated water is now used to supply all the copper mine’s water requirements. REXA actuators played a vital role in this successful four-year transition. Our self-contained Electraulic™ system locks the cylinder in place, when no movement is required, minimizing wear and tear on moving components and eliminating unnecessary power consumptions. REXA Electraulic™ Actuators have been engineered for use for constant modulating duty cycle and precise positioning independent of load variation. REXA’s actuation package supports various control system protocols including HART (Highway Addressable Remote Transducer) and Ethernet IP. Pipeline flow control is an excellent example where reliable positioning performance is necessary to prevent and minimize unscheduled downtime! Copper is a valuable metal used in many residential, commercial, and industrial products. From wiring and consumer electronics to HVAC systems to electrical vehicles, copper is an essential element necessary to produce such products. Copper mining is a complex process and water is its’ lifeblood. It allows for the separation and recovery of salable copper. Throughout the milling and flotation cell processed, over double the amount of water is required throughout the crush-grind-flotation-concentrate circuit. Poor control of the mine’s water supply can negatively impact process run-time, leading to constrained production levels and hurting the bottom line. Additionally, as a mine ages, copper ore grade generally decline. To maintain target recovery rates, mines must process more material called ore tons. As time passes this adds to the mine’s overall water consumption. Around the world mining companies are working to develop a more sustainable production method to address environmental concerns and maintain stable operations. Chile is home to the world’s largest copper mine and it is the country’s largest water consumer. In 2018, the mine underwent an expansion project to implement a desalination plant and added a necessary pipeline to feed the operation. The goal was to operate entirely on desalinated water by the year 2030. In 2020, 10 years ahead of the planned schedule, that goal was achieved. The mine’s water source is pumped over 3,100 meters above sea level to a reservoir near the mine. From there, the water is then delivered trhough a 36-inch discharge line and is controlled with an 18-inch globe valve. The pond is the sole water supply to the mill and concentrator.     Literature Download the entire Success Story here to learn more!  Download

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Collections

Collections Gates are commonly used within a collection system to control flows. Automation of these gates requires an actuator that can reliably respond to changing conditions. During a wet weather event, the actuators on these gates are the critical aspect of the entire high flow management strategy. A failure of actuators to respond can cause big problems. Imagine a scenario where a collection system interceptor station has both influent control and diversion gates. The flow typically runs through the control gate that can be modulated to pinch off or shut off flows, perhaps using in-house storage upstream within the collection system. During very high flow events, the diversion gate would divert to a local water way or a storage area.  The worst case scenario occurs if the control gate is pinched off/closed, but the diversion gate fails to open on account of an actuator failure. During an extreme wet weather event, such a failure could cause flooding upstream of this interceptor, potentially resulting in public or private infrastructure damage, as well as a black eye for the wastewater operations.  Literature Download the Collections Wet Weather Management Application Spotlight! Download

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UV Disinfection

UV Disinfection Background Wastewater treatment plants often employee ultraviolet (UV) disinfection as the last stage of treatment to meet strict bacterial limitations on plant discharges. A UV system’s reliability and efficiency is critical to mitigating the threat of permit violations and fines for the discharge of improperly disinfected wastewater effluent. During the UV disinfection process, treated wastewater is exposed to UV light, causing cellular damage to any microorganisms present. Therefore, these pathogens, such as viruses and bacteria, are incapable of reproduction or infection.  On open channel UV systems, either a controlling gate or weir structure regulate and maintain constant water levels over the UV lamps. For UV systems with horizontally-installed lamps, it is imperative to properly regulate wastewater levels to provide sufficient  UV exposure to contaminants. In addition, the UV system effluent gates serve as one of the last points of control before discharge.  Problem Poorly-controlled actuators on this application leads to a variety of problems. If the gate cannot accurately control the water level over the UV lamps and gets too high, there may not be enough UV light to treat the additional water flowing through the channel. Consequently, this leads to potential discharge permit violations. Conversely, if the water level gets too low, the UV lamps can overheat, leading to maintenance issues. From a fail-safe perspective, if the UV system is compromised for any reason, and the effluent gate does not close, the plant can discharge non-permit water.  Solution The reliability of REXA Linear and Rotary Actuators prevents downtime and maintenance costs on UV applications. More importantly, the superior control capabilities of REXA Linear and Rotary Actuators assures proper level control in plants’ UV channels. This allows them to meet disinfection standards for their effluent, reduce the threat of fines, and maximize UV bulb life. The easy addition of a fail-safe option to any REXA design gives the treatment plant peace of mind that a UV channel can be closed and isolated when an upset or emergency condition occurs. UV effluent control structures are tailor-made for the reliability, control, and fail-safe capabilities offered by REXA. Literature Download the UV Disinfection Effluent Level Control Application Spotlight! Download

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Headworks

Headworks It is common for one or more cast iron sluice gates to be employed within the headworks of a wastewater treatment plant to control the flows entering the facility from the collection system. These gates will most often remain fully open, but can be throttled to regulate flows during high-flow events. Above all, reliability of these sluice gates is of great importance to the treatment plant.  Many facilities do not modulate the main influent gates in the headworks due to the inoperability of the existing actuators. In such instances, the gates may be permanently chained in the open position, preventing the plant from fully utilizing the control structures in the headworks. Regardless, if the actuator controlling a headworks gate becomes inoperable to the point that it impedes or disrupts the flows coming into the wastewater treatment plant, big problems can arise by allowing too much or too little flow into the treatment plant.  REXA  Linear  and  Rotary  Actuator’s are ideal for headworks gates, allowing a plant to reliably operate these gates, as well as control and modulate them (an added benefit many plants do not yet employ). 

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Sludge Control

Sludge Control Moving and modulating sludge flow can be a difficult service given the viscous nature of sludge. REXA  Electraulic™  Technology  is ideally suited to help gain control of any flow control sludge applications in a treatment plant. REXA has many installations on modulating sludge control valves where actuators have performed flawlessly for 10+ years and counting.

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