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Climax Molybdenum Company <br /> Permit No.1977-342 Technical Revision (TR-35) <br /> to Reactor Tank#2. The piping will be arranged to allow either reactor to be used alone to permit maintenance <br /> without taking the plant offline. Each reactor will be provided with an agitator. Lime will not be supplied directly to <br /> the reactors, but via the lime/sludge mix tank situated above the reactors, where it will be mixed by an agitator <br /> with the returning recycled sludge.This lime coated sludge promotes HDS reactions,while the lime addition raises <br /> the pH to between 10 and 11 in the reactors to improve metals removal. Air will be introduced into the reactor <br /> tanks via coarse aeration to oxidize ferrous iron and manganese. The reactor tank effluent will be dosed with <br /> polymer and then flow to the clarifier where the resulting precipitate will be thickened. The clarifier is an elevated <br /> steel tank which will be situated within the WTP building to allow greater temperature control and protection from <br /> weather elements to reduce settling variability. A clarifier rake maintains solids fluidity and moves solids to the <br /> center cone as underflow. Clarifier underflow will be recycled to the lime/sludge mix tank using positive <br /> displacement sludge recycle pumps. The portion of the sludge that is not recycled will be routed for disposal in <br /> the TSF. This process includes pumping sludge to the sludge storage tank, which is equipped with a mixer to <br /> maintain solids in suspension until the sludge is pumped to the Bear Paw Pipeline (which flows to the TSF). <br /> Following sludge pumping events, water flushing procedures will be followed to reduce the potential for solids to <br /> settle and accumulate in plant or sludge disposal pipelines. <br /> The clarifier overflow will flow to gravity multi-media filters. An underdrain system will collect the filtered water. A <br /> portion of the water will be used for backwashing the filters and the balance will flow to the effluent tank. Each of <br /> the multi-media filter units will be backwashed regularly as needed. The backwash cycle consists of air scour <br /> from a blower system, followed by a water backwash plus air, then only water. The backwash wastewater will be <br /> pumped back to the Spent Backwash Tank and then to the reactor tanks for treatment. <br /> Neutralization is conducted through dissolving CO2 with utility water to create carbonic acid and injecting a <br /> slipstream of this carbonic acid into the Effluent Tank to neutralize the WTP effluent prior to discharge. The final <br /> plant effluent will be discharged to the WFR through an existing pipeline to the Williams Fork Pump Station. <br /> 2.2.1 Solids Handling and Sludge Disposal <br /> Sludge material not recycled to the lime/sludge mix tank will be stored in the sludge storage tank. Periodically, <br /> this sludge material will be pumped to the Bear Paw Pipeline to be routed to the TSF for disposal. Between <br /> pumping intervals,solids in the sludge storage tank will be maintained in suspension using a tank mixer. Following <br /> pumping of sludge, water will be pumped through the pipelines to reduce the potential for solids to settle and <br /> accumulate in the pipeline. Sludge disposal is anticipated to be conducted at an average rate of approximately <br /> 1,000 gallons per day (100 pounds of dry sludge per day). <br /> The sludge is comprised of lime and metal precipitate residuals. The TSF is designed to contain mill tailing which <br /> contain the same metals. The supernatant pond on the TSF is included in the process water system, so any water <br /> delivered with the sludge or contacting the sludge will be recycled through the mill process water system and <br /> routed back to the WTP for treatment prior to discharge. Due to the small quantity of WTP sludge being disposed <br /> at the TSF when compared to the overall size of the TSF, the metal loading attributed to the sludge disposal is <br /> insignificant (the volume of daily sludge production is anticipated to be approximately 0.00025% of the total mass <br /> of tailings deposited in the TSF daily). The TSF has been designed, and is being operated, with effective <br /> engineering controls and redundancies, including seep water collection and return, a groundwater interceptor <br /> system, and regular internal and external monitoring and inspections. The TSF and associated seep water <br /> collection facilities are designated as EPFs in the facility EPP. <br /> 2.2.2 Process Control Strategy <br /> The WTP has been designed with the level of control and redundancy needed to achieve compliance with CDPS <br /> permit requirements and environmental protection of the WFR. This includes extensive automatic control of <br /> systems based on installed instrumentation, while providing operators with alarms and the ability to run systems <br /> manually, if required. The control strategy is designed for automatic and controlled shutdown in the event of <br /> system failures or power outages and will provide for automatic collection and recycle of off specification water. <br /> April 2022 <br />