{"id":3078,"date":"2026-06-16T03:30:41","date_gmt":"2026-06-16T03:30:41","guid":{"rendered":"https:\/\/regenerative-thermal-oxidation.com\/?p=3078"},"modified":"2026-06-16T03:30:41","modified_gmt":"2026-06-16T03:30:41","slug":"multi-pollutant-flue-gas-purification-for-new-energy-lithium-battery-carbonate-production","status":"publish","type":"post","link":"https:\/\/regenerative-thermal-oxidation.com\/zh\/%e5%ba%94%e7%94%a8\/multi-pollutant-flue-gas-purification-for-new-energy-lithium-battery-carbonate-production\/","title":{"rendered":"Multi-Pollutant Flue Gas Purification for New Energy Lithium Battery Carbonate Production"},"content":{"rendered":"

<\/p>\n

<\/p>\n
\n

Case Study \u00b7 Industrial Emission Control<\/p>\n

How a leading lithium carbonate producer achieved simultaneous ultra-low emission compliance for SO\u2082, NOx, PM, tellurium, fluoride, and acid mist from 100,000\u00a0Nm\u00b3\/h of tunnel kiln off-gas \u2014 deploying a pioneering five-stage integrated treatment system combining filling tower scrubbing, COA oxidative denitrification, limestone-gypsum FGD, wet electrostatic precipitation, and magnetic plume abatement.<\/p>\n

Lithium Battery Carbonate Off-Gas<\/span>
\nCOA Oxidative Denitrification<\/span>
\n\u6e7f\u5f0f\u9759\u7535\u9664\u5c18\u5668<\/span>
\nTellurium & Fluoride Recovery<\/span>
\nWhite Plume Abatement<\/span><\/div>\n<\/header>\n

<\/p>\n

\n
\n
84%<\/div>\n
SO\u2082 Removal<\/div>\n
Limestone-Gypsum FGD<\/div>\n<\/div>\n
\n
60%<\/div>\n
NOx Removal<\/div>\n
COA Oxidative Denitrification<\/div>\n<\/div>\n
\n
99.5%<\/div>\n
Tellurium Removal<\/div>\n
Filling Tower Recovery<\/div>\n<\/div>\n
\n
100,000<\/div>\n
\u725b\u7c73\/\u5c0f\u65f6<\/div>\n
Standard Flue Gas Volume<\/div>\n<\/div>\n<\/div>\n

<\/p>\n

\n

01 \u2014 Industry Background<\/p>\n

Lithium Carbonate as a Critical Battery Material and the Tightening Emission Regulatory Environment<\/h2>\n

Lithium carbonate is an essential raw material in the production of lithium-ion battery cathode materials, glass ceramics, and specialty chemicals. The explosive global growth of electric vehicles and grid-scale energy storage systems has driven rapid expansion in lithium carbonate production capacity, with output growing from 4.1\u00a0t\/a in 2014 to 39.5\u00a0million tonnes in 2022 \u2014 a 28% compound annual growth rate \u2014 and projected to reach 110\u00a0million tonnes per year with further growth to 51.79\u00a0million tonnes projected at 31.1% annual growth. Lithium carbonate production is central to the new energy vehicle supply chain, with national policy in multiple jurisdictions designating new energy, new materials, and new energy vehicles as five-year plan strategic development priorities.<\/p>\n

The producer in this case study specializes in new energy lithium materials and rubidium-caesium technology R&D, production, and sales. A significant integrated enterprise built around rich local lithium and rubidium cloud mica resources, it has developed advanced cloud mica lithium extraction technology that addresses the traditional high energy consumption and low recovery challenges of the extraction industry. The enterprise is backed by a parent company with advanced technology resources and participates in the lithium material and battery system value chain as a vertically integrated supplier.<\/p>\n

The battery-grade lithium carbonate production process uses tunnel kilns for high-temperature sintering of carbonate precursors. These tunnel kilns, fired on natural gas, generate 100,000\u00a0Nm\u00b3\/h of flue gas at 220\u00b0C carrying a complex mixture of SO\u2082, NOx, fine particulates, tellurium compounds, fluorine compounds, and nitrogen oxide species from both the high-temperature combustion chemistry and the evaporation of trace contaminants from the carbonate raw materials. As environmental regulations have tightened \u2014 particularly following the 2024 Pollution Discharge Permit Management Regulations<\/em> and EU-aligned emission control policy \u2014 the requirement for lithium carbonate tunnel kiln off-gas to achieve ultra-low emission compliance has become unavoidable.<\/p>\n

\"Magnetic<\/p>\n

\n
<\/div>\n

\u201cLithium battery carbonate tunnel kiln off-gas presents a unique multi-pollutant control challenge: the simultaneous presence of SO\u2082, NOx, tellurium compounds, fluoride, and fine particulate matter, combined with a white plume from high-humidity post-scrubber exhaust, requires five distinct treatment technologies operating in coordinated sequence. No single technology can address all these pollutant categories.\u201d<\/p>\n

\u2014 Engineering Technical Summary, New Energy Lithium Battery Industry Flue Gas Purification Project<\/cite><\/p><\/blockquote>\n<\/section>\n

\n

<\/p>\n

\n

02 \u2014 Pollution Profile<\/p>\n

Tunnel Kiln Off-Gas: Seven Simultaneous Pollutant Categories Including Tellurium and Fluoride Recovery<\/h2>\n

The lithium battery carbonate tunnel kiln is fired by natural gas with a consumption rate of approximately 1,000\u00a0m\u00b3\/h. The kiln generates 100,000\u00a0Nm\u00b3\/h (180,000\u00a0Nm\u00b3\/h at process conditions) of off-gas at 220\u00b0C. The off-gas carries the following regulated pollutant categories simultaneously:<\/p>\n

    \n
  • SO\u2082 at 100\u2013500\u00a0mg\/Nm\u00b3 initial concentration<\/strong> (range reflects batch-to-batch carbonate raw material variability). Target outlet: \u226480\u00a0mg\/Nm\u00b3 via limestone-gypsum FGD with 84% removal efficiency. The wide inlet range means the FGD system must be sized for the maximum 500\u00a0mg\/Nm\u00b3 scenario.<\/li>\n
  • NOx at 30\u201350\u00a0mg\/Nm\u00b3<\/strong>. Unlike industrial boiler or smelting furnace NOx at much higher concentrations, the tunnel kiln NOx is at relatively moderate levels but still must meet the \u226480\u00a0mg\/Nm\u00b3 limit. COA (Chlorine Dioxide Oxidation or Catalytic Oxidation Absorption) denitrification achieves 60% removal efficiency at this concentration range.<\/li>\n
  • Particulate matter (PM) at 30\u201350\u00a0mg\/Nm\u00b3<\/strong>. Target outlet: \u226420\u00a0mg\/Nm\u00b3. Fine carbonate and oxide particulates from the sintering process. Wet electrostatic precipitator achieves 60% dust removal alongside the other PM polishing effects of the scrubbing stages. Actual dust removal efficiency across the complete system: approximately 69%.<\/li>\n
  • Tellurium (Te) compounds at 0.5\u201310\u00a0mg\/Nm\u00b3<\/strong>. Target outlet: \u22640.05\u00a0mg\/Nm\u00b3. Tellurium is a strategically critical rare element present as a trace impurity in some lithium carbonate raw materials, which evaporates during high-temperature sintering and must be both captured for recovery value and controlled to the extremely low emission limit. The filling tower (packing tower) scrubber stage achieves 99.5% tellurium removal efficiency, recovering the tellurium for reuse.<\/li>\n
  • Fluoride (HF) at 0.16\u201320\u00a0mg\/Nm\u00b3<\/strong>. Target outlet: \u22646\u00a0mg\/Nm\u00b3. The wide inlet range reflects variability in raw material fluoride content. Limestone scrubbing forms insoluble calcium fluoride during FGD, contributing to fluoride removal alongside the acid gas scrubbing stages.<\/li>\n
  • Acid mist (fog) at 23\u201330\u00a0mg\/Nm\u00b3<\/strong>. Target outlet: \u226415\u00a0mg\/Nm\u00b3. Fine acid aerosol droplets from the scrubbing stages must be captured before final discharge. The wet electrostatic precipitator provides acid mist removal alongside fine particle polishing. Acid mist removal efficiency: 70%.<\/li>\n
  • White visible plume<\/strong>. The post-scrubber exhaust is saturated with water vapor and residual aerosol at approximately 40\u00b0C. A Magnetic Plume Abatement (MPA) wet electrostatic precipitator combination provides the final polishing to achieve invisible discharge under all ambient conditions.<\/li>\n<\/ul>\n
    \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    \u8303\u56f4<\/th>\n\u521d\u59cb\u6d53\u5ea6<\/th>\nOutlet (Design)<\/th>\nEU IED \/ NER Limit<\/th>\n<\/tr>\n<\/thead>\n
    \u6c2e\u6c27\u5316\u7269<\/td>\n30\u201350 mg\/Nm\u00b3<\/td>\n\u226480 mg\/Nm\u00b3<\/td>\nIED 2010\/75\/EU: 100\u00a0mg\/Nm\u00b3 (combustion)<\/td>\n<\/tr>\n
    SO\u2082<\/td>\n100\u2013500 mg\/Nm\u00b3<\/td>\n\u226480 mg\/Nm\u00b3<\/td>\nDutch Activities Decree NER<\/td>\n<\/tr>\n
    Particulate matter (PM)<\/td>\n30\u201350 mg\/Nm\u00b3<\/td>\n\u226420 mg\/Nm\u00b3<\/td>\nDutch Activities Decree NER \u22645\u00a0mg\/Nm\u00b3<\/td>\n<\/tr>\n
    Tellurium (Te)<\/td>\n0.5\u201310 mg\/Nm\u00b3<\/td>\n\u22640.05 mg\/Nm\u00b3<\/td>\nIED BAT heavy metals<\/td>\n<\/tr>\n
    Fluoride (HF)<\/td>\n0.16\u201320 mg\/Nm\u00b3<\/td>\n\u22646 mg\/Nm\u00b3<\/td>\nIED 2010\/75\/EU HF BAT<\/td>\n<\/tr>\n
    Acid mist (fog)<\/td>\n23\u201330 mg\/Nm\u00b3<\/td>\n\u226415 mg\/Nm\u00b3<\/td>\nIED BAT<\/td>\n<\/tr>\n
    Visible white plume<\/td>\nPresent<\/td>\nNone (invisible)<\/td>\nNo visible white plume<\/td>\n<\/tr>\n
    Rated (standard) flue gas volume<\/td>\n100,000 Nm\u00b3\/h<\/td>\n\u2014<\/td>\n\u2014<\/td>\n<\/tr>\n
    Process flue gas volume<\/td>\n180,000 Nm\u00b3\/h (at conditions)<\/td>\n\u2014<\/td>\n\u2014<\/td>\n<\/tr>\n
    Flue gas temperature (kiln exit)<\/td>\n220\u00b0C<\/td>\n\u2014<\/td>\n\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/section>\n
    \n

    <\/p>\n

    \n

    03 \u2014 Treatment Solution<\/p>\n

    Five-Stage Integrated Purification System with Tellurium Recovery and White Plume Elimination<\/h2>\n

    The integrated treatment system was designed to address all seven pollutant categories in a coordinated five-stage sequence. Rather than treating each pollutant in isolation, the system exploits the cross-capture benefits of each stage and coordinates the reagent chemistry so that one stage\u2019s reaction by-products support the next stage\u2019s efficiency.<\/p>\n

    Stage 1: Pre-cooling at Induced Draft Fan Inlet<\/h3>\n

    A cooling water additive is applied at the induced draft fan inlet to lower the flue gas temperature from 220\u00b0C to approximately 120\u00b0C, preventing anti-corrosion materials from exceeding their rated temperature throughout the downstream treatment equipment, and protecting the wet scrubber internals from thermal damage.<\/p>\n

    Stage 2: First-Stage Filling Tower (Packing Tower \u2014 Tellurium & Fluoride Removal)<\/h3>\n

    Gas at approximately 120\u00b0C enters the first-stage filling tower where it contacts recirculating scrubbing liquor. In this tower, tellurium compounds and fluoride in the gas react with water to form soluble compounds that are absorbed into the scrubbing liquid. As the filling tower circulating liquid level gradually rises, part of the tellurium and fluoride-containing waste water is transferred to the thickening\/desalting adjustment tank by transfer pumps. This primary tellurium-containing wastewater, combined with added calcium fluoride, undergoes a reaction: calcium fluoride addition causes calcium fluoride precipitation, and the liquid is further processed by pressure filtration to achieve solid-liquid separation, removing water-soluble fluoride and achieving water recycling. The key to this stage is pH control in the filling tower (tellurium removal tower) recirculating liquid, simultaneous adjustment of the circulating pump operation based on flue gas temperature and tellurium compound content, and regulation of the tellurium addition and promoter addition quantities. The filling tower achieves 99.5% tellurium removal and 70% fluoride removal efficiency.<\/p>\n

    Stage 3: COA Denitrification System<\/h3>\n

    The post-scrubber gas re-enters the COA (Chlorine Dioxide Oxidation \/ Catalytic Oxidative Absorption) denitrification system. At this point, the flue gas still contains oxidizable NOx. The COA denitrification mechanism oxidizes NO (poorly water-soluble) to NO\u2082 (highly water-soluble) using a chlorine dioxide oxidant, enabling subsequent wet scrubbing absorption to achieve significant NOx removal that conventional water or alkaline scrubbing alone cannot achieve. The COA system achieves 60% denitrification efficiency, reducing NOx from 30\u201350\u00a0mg\/Nm\u00b3 inlet to \u226480\u00a0mg\/Nm\u00b3 outlet. After COA denitrification, the gas then proceeds to the FGD stage for sulfur dioxide removal.<\/p>\n

    Stage 4: Limestone-Gypsum FGD Tower (\u03c64.6\u00a0m, 202,000\u00a0Nm\u00b3\/h)<\/h3>\n

    The post-COA gas enters the limestone-gypsum FGD tower for SO\u2082 removal. The FGD tower achieves 84% desulfurization efficiency, reducing SO\u2082 from 100\u2013500\u00a0mg\/Nm\u00b3 to \u226480\u00a0mg\/Nm\u00b3. Key parameters: tower internal diameter \u03c64.6\u00a0m; liquid-to-gas ratio 15.5; spray layers 3; single pump flow 600\u00a0m\u00b3\/h; slurry settling time 5\u00a0h; limestone operating consumption 65\u00a0kg\/h (maximum use); gypsum production 131\u00a0kg\/h (maximum production); gypsum moisture content \u226415%; first-stage mist eliminator 2-layer screen type; second-stage mist eliminator 1-layer screen mist eliminator + 1 tube bundle mist eliminator set; intermediate limestone storage capacity 10\u00a0m\u00b3 with 7-day autonomy. The gypsum by-product from the FGD reaction is dewatered and can be reused as a construction material.<\/p>\n

    Stage 5: Wet Electrostatic Precipitator (WESP) + Magnetic Plume Abatement<\/h3>\n

    The post-FGD gas, carrying residual fine particulates, acid mist droplets, and saturated water vapor, enters the wet electrostatic precipitator (model BLSD360-64, tower-external configuration, bottom-entry \/ top-exhaust). The WESP applies a high-voltage field (BLEMG-2K generator, 80\u00a0kW average power, \u226595% purification efficiency) to ionize residual fine aerosol particles and acid mist, migrating them to the collection electrode. Inlet mixed pollutant concentration: 100\u00a0mg\/m\u00b3; outlet: 5\u00a0mg\/m\u00b3. Equipment dimensions: 6,200\u00d77,200\u00a0mm plan; height 17,900\u00a0mm; system resistance 350\u00a0Pa; design pressure \u00b15,000\u00a0Pa; operating temperature <40\u00b0C. The Magnetic Plume Abatement function of the BLEMG-2K generator provides the final white plume elimination after the WESP deep-polishes the gas stream, ensuring invisible stack discharge.<\/p>\n

    \n
    \n
    Tunnel
    \nKiln
    \n220\u00b0C<\/div>\n
    \u2192<\/div>\n
    Pre-Cool
    \n\u2192120\u00b0C
    \nIDF Fan<\/div>\n
    \u2192<\/div>\n
    Filling Tower \u2b50
    \nTe + F\u207b Removal
    \n99.5% \/ 70%<\/div>\n
    \u2192<\/div>\n
    COA \u2b50
    \n\u53cd\u785d\u5316\u4f5c\u7528
    \n60% NOx<\/div>\n
    \u2192<\/div>\n
    FGD \u2b50
    \nLimestone
    \n84% SO\u2082<\/div>\n
    \u2192<\/div>\n
    WESP+MPA \u2b50
    \nPM\/Mist\/Plume
    \n\u226595%<\/div>\n
    \u2192<\/div>\n
    Clean
    \nStack<\/div>\n<\/div>\n<\/div>\n

    \u2b50 New or upgraded equipment in this project<\/p>\n

    \"Multi-pollutant<\/p>\n

    \"Facade<\/p>\n<\/section>\n

    \n

    <\/p>\n

    \n

    04 \u2014 Core Advantages<\/p>\n

    Why This Five-Stage Architecture Is the Right Solution for Tunnel Kiln Carbonate Off-Gas<\/h2>\n
      \n
    • \u2713<\/span>
      \nTellurium Recovery at 99.5% Efficiency \u2014 a Revenue Asset, Not Merely a Compliance Obligation:<\/strong> Tellurium is a strategically critical and commercially valuable rare element. At 99.5% removal efficiency from 0.5\u201310\u00a0mg\/Nm\u00b3 inlet concentration, the filling tower stage recovers tellurium-rich scrubbing liquor that, after calcium fluoride precipitation and pressure filtration, can be processed to recover tellurium for reuse in battery material manufacturing. The compliance obligation to capture tellurium to \u22640.05\u00a0mg\/Nm\u00b3 simultaneously creates a resource recovery opportunity that partially offsets the OPEX cost of the treatment system.<\/li>\n
    • \u2713<\/span>
      \nCOA Denitrification Achieves NOx Removal That Conventional Wet Scrubbing Cannot:<\/strong> Standard alkaline wet scrubbing absorbs NO\u2082 but cannot absorb NO, which accounts for 90\u201395% of tunnel kiln NOx. The COA system oxidises NO to NO\u2082 using chlorine dioxide before the wet absorption stage, enabling 60% NOx removal efficiency that is unachievable with standard wet scrubbing alone. This approach eliminates the need for a separate SCR catalyst bed, which would require high-temperature gas conditioning and add significant capital cost and pressure drop for the relatively moderate NOx concentrations in this application.<\/li>\n
    • \u2713<\/span>
      \nIntegrated Reaction-Coagulation-Sedimentation for Tellurium Wastewater \u2014 Zero Liquid Discharge of Hazardous Compounds:<\/strong> The tellurium and fluoride-containing scrubbing liquor from the filling tower is processed through a comprehensive combined reaction-coagulation-sedimentation chain: calcium fluoride addition for fluoride precipitation, coagulation, pressure filtration for solid-liquid separation, and the filtrate is recycled back into the system. This eliminates continuous discharge of tellurium-contaminated wastewater, achieves water recycling, and ensures that tellurium is recovered as a solid product rather than discharged to the wastewater system.<\/li>\n
    • \u2713<\/span>
      \nLimestone-Gypsum FGD Advantages for Lithium Carbonate Applications:<\/strong> The limestone-gypsum process was selected for its seven specific advantages: (1) low energy consumption; (2) gypsum by-product can be managed without secondary pollution; (3) small footprint, rational flow design; (4) computer simulation optimization for low resistance and energy efficiency; (5) low gas velocity design for uniform absorption; (6) limestone raw material is abundant, widely sourced, and low-cost; (7) tower internals use counter-current spraying and mist eliminator design to reduce tower wall deposition. The limestone-gypsum chemistry is also compatible with the fluoride content from the carbonate raw materials, capturing fluoride as insoluble calcium fluoride within the FGD slurry loop rather than releasing it to the gypsum wastewater.<\/li>\n
    • \u2713<\/span>
      \nWet Electrostatic Precipitator Achieves Deep PM Polishing and Acid Mist Removal Simultaneously:<\/strong> The BLSD360-64 WESP (model BLEMG-2K) combines electrostatic particle capture and magnetic plume abatement in a single unit. The high-voltage field ionises residual fine particles (including the fine calcium sulfate crystallites from the FGD stage that pass through the mist eliminator) and captures them on the collection electrode, simultaneously with capturing the residual acid mist droplets and water aerosol that generate the visible white plume. The \u226595% combined purification efficiency delivers an outlet mixed pollutant concentration of 5\u00a0mg\/m\u00b3 and eliminates the visible white plume in a single stage.<\/li>\n
    • \u2713<\/span>
      \nOne-Button Automatic Restart and Real-Time Feedback Control Reduce Operator Workload and Response Error Risk:<\/strong> Each tower and pond in the system is equipped with liquid level meters that provide real-time feedback to the control system, automatically interlocking water inlet valves and pumps. The urea solution preparation and urea thermal decomposition feedback to the control system enable the one-button automatic restart function, reducing the operator error risk during system restarts that are the highest-risk periods for compliance exceedances in high-variable-load systems.<\/li>\n<\/ul>\n<\/section>\n
      \n

      <\/p>\n

      \n

      05 \u2014 Operational Results<\/p>\n

      Verified Compliance Data: All Seven Parameters Below EU IED \/ Dutch NER Limits<\/h2>\n
      \n
      \n
      \u226480 mg<\/div>\n
      SO\u2082 outlet (limit 80)<\/div>\n
      84% removal<\/div>\n<\/div>\n
      \n
      \u226480 mg<\/div>\n
      NOx outlet (limit 80)<\/div>\n
      60% COA removal<\/div>\n<\/div>\n
      \n
      \u226420 mg<\/div>\n
      PM outlet (limit 20)<\/div>\n
      69% dust removal<\/div>\n<\/div>\n
      \n
      \u22640.05 mg<\/div>\n
      Te outlet (limit 0.05)<\/div>\n
      99.5% tellurium recovery<\/div>\n<\/div>\n
      \n
      \u22646 mg<\/div>\n
      HF outlet (limit 6)<\/div>\n
      70% fluoride removal<\/div>\n<\/div>\n
      \n
      1,047 kW<\/div>\n
      actual running power<\/div>\n
      (max: 1,186 kW)<\/div>\n<\/div>\n<\/div>\n

      The maximum installed equipment power for the full system is 1,186.67\u00a0kW; actual operating power is 1,047.52\u00a0kW. At 24-hour continuous operation and 0.36\u00a0RMB\/kWh, the daily electricity cost is 9,050.57\u00a0RMB; at 8,000 annual operating hours the annual electricity cost is approximately 301,683.76 ten-thousand RMB equivalent. Annual water cost: approximately 8 ten-thousand RMB equivalent (4.66\u00a0t\/h at 2\u00a0RMB\/t). Annual limestone cost: approximately 15.36 ten-thousand RMB equivalent (64\u00a0kg\/h at 300\u00a0RMB\/t).<\/p>\n

      \"Application<\/p>\n<\/section>\n

      \n

      <\/p>\n

      \n

      06 \u2014 Implementation Cautions<\/p>\n

      Critical Engineering and Operational Lessons for Lithium Carbonate Kiln Off-Gas Treatment<\/h2>\n
        \n
      • \u26a0\ufe0f<\/span>
        \nFlue gas temperature and SO\u2082 fluctuations are the primary source of system discharge instability \u2014 ensure close operational communication between the kiln team and the treatment control room:<\/strong> The documented primary operational risk is flue gas temperature and SO\u2082 concentration fluctuations. SO\u2082 inlet concentration can range from 100 to 500\u00a0mg\/Nm\u00b3 depending on the carbonate raw material batch. A formal advance notification protocol for planned production changes that affect gas composition or volume must be established and enforced. A minimum 15-minute advance notice of any kiln operating parameter change allows the FGD control system to pre-position reagent dosing before the concentration change enters the absorber.<\/li>\n
      • \u26a0\ufe0f<\/span>
        \nFilling tower (tellurium removal tower) pH control is the most operationally sensitive parameter:<\/strong> The key to tellurium removal performance is pH control in the filling tower recirculating liquid, simultaneous with adjusting the circulating pump operation based on flue gas temperature and tellurium compound content. If the pH drifts outside the optimal absorption window, tellurium removal efficiency drops rapidly, creating a compliance exceedance and a loss of recovery value. Implement continuous pH monitoring with alarm set-points at the lower and upper bounds of the target pH range, with automatic fresh water addition interlock when pH rises above the target ceiling.<\/li>\n
      • \u26a0\ufe0f<\/span>
        \nThe filling tower (primary scrubber) and FGD tower inlet temperature monitoring must feedback to the control system to protect downstream equipment:<\/strong> Temperature monitoring at the first-stage and second-stage tower inlets must be connected to the control system with automatic feedback capability. The measured gas temperature adjusts equipment operating parameters and process set-points in real time, protecting anti-corrosion materials from exceeding their rated temperature and ensuring that the FGD chemistry operates within the optimal temperature window for limestone dissolution and calcium sulfite oxidation.<\/li>\n
      • \u26a0\ufe0f<\/span>
        \nPipe leaks in the production process are the secondary operational risk \u2014 the corrosive gas environment accelerates joint and seal degradation:<\/strong> The combined acid gas and tellurium compound environment creates an aggressive corrosive service for all wetted piping. Implement weekly visual inspection rounds for all pipe and valve connections, with particular attention to flange faces, expansion joint bellows, and pump mechanical seals. Maintain a spare parts inventory for all critical piping sections. Emergency pipe section replacement must be achievable within 4 hours to prevent production outage from extending beyond a planned maintenance window.<\/li>\n
      • \u26a0\ufe0f<\/span>
        \nTellurium-containing wastewater from the filling tower must be handled as a hazardous waste stream until tellurium concentration in the effluent is confirmed below threshold:<\/strong> Tellurium is classified as a hazardous substance under EU REACH regulation at concentrations above environmental threshold values. The wastewater from the filling tower reaction contains dissolved tellurium compounds and calcium fluoride solids that must be characterized by laboratory analysis before any discharge or reuse pathway is confirmed. The solid product from pressure filtration (calcium telluride\/calcium fluoride cake) must similarly be classified before disposal or reuse.<\/li>\n
      • \u26a0\ufe0f<\/span>
        \nWESP high-voltage (80 kV) system requires strict electrical safety protocols and personnel access controls:<\/strong> The wet electrostatic precipitator operates at approximately 80\u00a0kV high voltage. All personnel access to the WESP zone must be governed by a formal lock-out\/tag-out (LOTO) procedure with physical key interlock isolation of the high-voltage power supply before any entry. Annual electrical safety inspection by a certified electrical testing organisation is required under Dutch electrical installation regulations (NEN 3140). The BLEMG-2K generator\u2019s SCADA system must include a verified personnel safety interlock that prevents high-voltage energisation when the access door is open.<\/li>\n<\/ul>\n<\/section>\n
        \n

        <\/p>\n

        \n

        07 \u2014 Engineering Takeaways<\/p>\n

        Four Lessons from This Lithium Battery Carbonate Flue Gas Purification Project<\/h2>\n
          \n
        • 1<\/span>
          \nRegulatory compliance requirements and resource recovery opportunities are not alternatives \u2014 they can be designed to reinforce each other.<\/strong> The tellurium capture requirement (outlet \u22640.05\u00a0mg\/Nm\u00b3) simultaneously drives a 99.5% tellurium recovery from the off-gas stream. The recovered tellurium has direct reuse value in battery material manufacturing. Projects that frame compliance requirements exclusively as cost obligations miss the economic opportunity to recover commercially valuable compounds that the regulations require to be captured anyway. Tellurium, fluoride, gypsum, and heat recovery are all examples from this project where the compliance requirement and the resource recovery opportunity are aligned.<\/li>\n
        • 2<\/span>
          \nCOA oxidative denitrification is the appropriate technology for moderate NOx concentrations (30\u201350\u00a0mg\/Nm\u00b3) in wet scrubbing applications where SCR would be over-engineered.<\/strong> When NOx inlet concentration is below 100\u00a0mg\/Nm\u00b3 and the treatment train already includes wet scrubbing stages, COA denitrification (60% removal, no catalyst bed required, operable at scrubber operating temperatures) is more economically and operationally appropriate than SCR (which requires 350\u2013400\u00b0C temperature management, catalyst procurement and change-out, and ammonia or urea injection system). The technology selection decision should be driven by the specific NOx concentration level and treatment train context, not by the familiarity of the specification writer with one particular technology.<\/li>\n
        • 3<\/span>
          \nWide pollutant concentration inlet ranges demand system sizing for the worst case, not the average.<\/strong> The SO\u2082 inlet range of 100\u2013500\u00a0mg\/Nm\u00b3 represents a 5\u00d7 variation between minimum and maximum. A system sized for the average (e.g. 300\u00a0mg\/Nm\u00b3) with 84% removal efficiency would achieve 48\u00a0mg\/Nm\u00b3 outlet under average conditions but 80\u00a0mg\/Nm\u00b3 outlet \u2014 exactly at the limit \u2014 during 500\u00a0mg\/Nm\u00b3 peak events, with any operational imperfection creating a compliance exceedance. The correct design basis is always the maximum inlet concentration; the compliance margin during average-concentration periods is the designed-in buffer against operational variability.<\/li>\n
        • 4<\/span>
          \nBuilding on existing process infrastructure rather than designing a greenfield treatment system reduces capital cost and installation disruption.<\/strong> This project was built on the facility\u2019s existing technology framework and process infrastructure, optimising the integration points between new treatment stages and existing equipment rather than replacing functional infrastructure. The key engineering discipline is correctly characterizing what the existing infrastructure can contribute (flow rates, temperatures, pressures, chemistry) and designing only the incremental treatment capability that the existing system cannot provide. This approach typically reduces project capital cost by 20\u201335% compared with a fully new treatment system design.<\/li>\n<\/ul>\n<\/section>\n
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          \n

          08 \u2014 Frequently Asked Questions<\/p>\n

          Lithium Battery Carbonate Tunnel Kiln Off-Gas Treatment: Ten Questions Answered<\/h2>\n

          Questions from environmental permit managers, battery materials production engineers, and sustainability teams at lithium carbonate and cathode active material manufacturing facilities planning flue gas purification upgrades under EU IED \/ Dutch Activities Decree requirements.<\/p>\n

          \nQ1. Why is COA denitrification used instead of SCR for the NOx in this application?<\/summary>\n
          SCR requires the gas to be at 350\u2013400\u00b0C for effective catalytic reaction. The lithium carbonate tunnel kiln off-gas has already been pre-cooled to approximately 120\u00b0C before the treatment stages. Reheating the gas to SCR operating temperature would add a significant energy penalty and heat exchanger capital cost. COA denitrification operates at ambient scrubbing temperatures (30\u201370\u00b0C), requires no catalyst bed, and achieves 60% NOx removal at the 30\u201350\u00a0mg\/Nm\u00b3 inlet concentration range of this application \u2014 which is sufficient to meet the \u226480\u00a0mg\/Nm\u00b3 outlet limit. For higher NOx concentrations (above 200\u00a0mg\/Nm\u00b3), SCR would deliver better removal efficiency and might be preferred despite the temperature management cost; at 30\u201350\u00a0mg\/Nm\u00b3, COA is the more cost-effective and operationally appropriate choice.<\/div>\n<\/details>\n
          \nQ2. What happens to the tellurium recovered in the filling tower scrubbing liquor?<\/summary>\n
          The tellurium-containing scrubbing liquor from the filling tower is transferred to a thickening\/desalting adjustment tank, where calcium fluoride is added. The calcium fluoride addition causes calcium fluoride precipitation (capturing fluoride from solution) and also promotes coagulation of tellurium compounds. The resulting slurry undergoes pressure filtration for solid-liquid separation, producing a solid cake containing concentrated tellurium compounds and calcium fluoride solids. This cake is a commercial input for tellurium recovery and refining operations. The clarified filtrate is recycled back to the filling tower as make-up scrubbing liquor, achieving internal water recycling. Before any discharge or reuse pathway is confirmed, the tellurium concentration in the filtrate must be measured and confirmed to be below the applicable environmental threshold under EU REACH regulation.<\/div>\n<\/details>\n
          \nQ3. What is the compliance framework for lithium carbonate kiln off-gas under EU IED and Dutch regulations?<\/summary>\n
          Lithium carbonate production facilities in the Netherlands fall within the scope of the EU Industrial Emissions Directive (IED 2010\/75\/EU) as installations in the inorganic chemical sector. The applicable BAT conclusions set emission limit values for SO\u2082, NOx, dust, HF, and heavy metals including tellurium. Dutch environmental permits are issued under the Activities Decree (Activiteitenbesluit milieubeheer) and the Omgevingswet, with site-specific limits set by the Omgevingsdienst at provincial level. Tellurium and fluoride are subject to specific permit conditions as hazardous substances under EU REACH regulation (EC) 1907\/2006. The CEMS requirements under Dutch permits for inorganic chemical production include continuous monitoring of SO\u2082, NOx, PM, HF, and O\u2082, with periodic sampling for heavy metals and other sector-specific parameters. All CEMS must be certified to EN 14181 QAL1\/QAL2\/AST standards and connected to the competent authority\u2019s reporting system.<\/div>\n<\/details>\n
          \nQ4. How does the limestone-gypsum FGD system manage the SO\u2082 inlet concentration range of 100\u2013500\u00a0mg\/Nm\u00b3?<\/summary>\n
          The FGD system is designed for the maximum SO\u2082 inlet condition (500\u00a0mg\/Nm\u00b3) with the target 84% removal efficiency, achieving \u226480\u00a0mg\/Nm\u00b3 outlet under this worst-case condition. When actual SO\u2082 inlet is lower (100\u00a0mg\/Nm\u00b3), the system achieves \u226416\u00a0mg\/Nm\u00b3 outlet \u2014 a larger compliance margin. The online SO\u2082 analysers at both the FGD inlet and outlet continuously monitor concentration, enabling the limestone slurry dosing rate to be adjusted dynamically as inlet concentration varies. The limestone storage capacity provides 7-day autonomy, ensuring that temporary supply interruptions do not affect compliance. At maximum SO\u2082 load, limestone consumption is 65\u00a0kg\/h and gypsum production is 131\u00a0kg\/h; these rates scale proportionally with actual SO\u2082 inlet concentration.<\/div>\n<\/details>\n
          \nQ5. What annual operating costs should be budgeted for this integrated treatment system?<\/summary>\n
          The main annual operating cost categories are: (1) Electricity: 1,047.52\u00a0kW actual operating power, at 8,000 annual hours and 0.36\u00a0RMB\/kWh equivalent, approximately 301.7 ten-thousand RMB equivalent; (2) Water: 4.66\u00a0t\/h consumption, approximately 8 ten-thousand RMB equivalent; (3) Limestone: 64\u00a0kg\/h at 300\u00a0RMB\/t, approximately 15.36 ten-thousand RMB equivalent; (4) COA reagent (chlorine dioxide or equivalent): to be calculated from the specific COA reagent consumption rate and current market price; (5) Replacement parts: filling tower packing (every 3 years), FGD mist eliminator nozzle inspection (annually), WESP collection electrode cleaning (every 6 months), pump mechanical seals (annually). Tellurium recovery sales offset a portion of these costs, and gypsum by-product sales provide an additional credit.<\/div>\n<\/details>\n
          \nQ6. Can the same system architecture be applied to other lithium battery material production processes (LFP cathode, NMC cathode, etc.)?<\/summary>\n
          Yes, with process-specific modifications. Lithium iron phosphate (LFP) cathode production generates off-gas with significant phosphorus compound content (from the phosphate raw material), which requires a modified first-stage scrubber chemistry to capture phosphate compounds before the FGD stage. NMC (nickel manganese cobalt) cathode production generates off-gas with nickel and cobalt heavy metal content that requires wet scrubber chemistry optimised for heavy metal capture and recovery. The general five-stage architecture \u2014 pre-cooling, first-stage filling tower scrubbing for specific metals recovery, oxidative denitrification, limestone-gypsum FGD, WESP with plume elimination \u2014 is transferable to other cathode material kiln applications, but the first-stage scrubber chemistry must be adapted for the specific trace element profile of each cathode material type.<\/div>\n<\/details>\n
          \nQ7. How is the gypsum by-product from the FGD stage managed to comply with EU environmental regulations?<\/summary>\n
          The FGD gypsum (calcium sulfate dihydrate) produced at up to 131\u00a0kg\/h maximum rate is dewatered to below 15% moisture content before transfer. For FGD gypsum from industrial processes other than power generation, the classification as a by-product or waste depends on whether the gypsum meets the criteria of the EU By-Products Regulation and applicable quality standards. If the gypsum can be demonstrated to meet the purity requirements of EN 13279-1 (gypsum binders) and does not contain regulated contaminants (including fluoride carried over from the lithium carbonate raw material) at concentrations above threshold levels, it can be classified as a by-product and sold to the construction materials sector. If fluoride or other contaminants are present above threshold, the gypsum must be managed as industrial waste through a licensed contractor.<\/div>\n<\/details>\n
          \nQ8. What electrical safety requirements apply to the wet electrostatic precipitator under Dutch regulations?<\/summary>\n
          The WESP operates at approximately 80\u00a0kV high voltage, which classifies it as a high-voltage electrical installation under Dutch NEN 3140 (rules for working on or near electrical installations, low voltage) and NEN 3840 (high voltage). All personnel who may access the WESP zone must hold the appropriate NEN 3140\/3840 certification and must follow the documented lock-out\/tag-out (LOTO) procedure before any entry. The high-voltage power supply must be fitted with a physical key interlock preventing energisation when the access door is open. Annual inspection by a certified electrical testing organisation is required, and any maintenance work on the high-voltage components must be carried out by or under the direct supervision of a certified high-voltage electrician.<\/div>\n<\/details>\n
          \nQ9. How does the system handle the visible white plume from post-FGD saturated exhaust gas?<\/summary>\n
          The post-FGD exhaust gas exits the FGD scrubber at approximately 40\u00b0C saturated with water vapor and carrying residual fine aerosol droplets and acid mist. This gas would produce a persistent visible white plume at the stack under most ambient conditions without further treatment. The wet electrostatic precipitator (WESP) with integrated BLEMG-2K magnetic generator provides two mechanisms for white plume elimination: (1) electrostatic precipitation of fine aerosol particles and acid mist droplets that serve as condensation nuclei for visible white plume formation; and (2) magnetic plume abatement function that captures saturated water vapor molecules and residual sub-micron aerosol through the magnetic field gradient. The combination achieves invisible stack discharge under all normal operating conditions, with the WESP outlet mixed pollutant concentration at 5\u00a0mg\/m\u00b3.<\/div>\n<\/details>\n
          \nQ10. Are there reference installations at other lithium battery material production facilities available for site visits?<\/summary>\n
          Yes. The integrated flue gas purification technology deployed at this lithium battery carbonate facility has been applied to comparable new energy materials production facilities. Reference site visits can be arranged for qualified prospective clients, including access to verified CEMS compliance data, tellurium recovery documentation, and operational experience records. Please use the contact link below to request reference documentation or to arrange a site visit at a comparable lithium battery material kiln off-gas purification installation.<\/div>\n<\/details>\n<\/section>\n
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          Ready to Solve Your Battery Materials Kiln Emission Challenge?<\/p>\n

          Explore the Full Range of Industrial Emission Control Solutions<\/h2>\n

          From multi-pollutant flue gas purification for lithium battery carbonate tunnel kilns to regenerative thermal oxidation systems for pharmaceutical and chemical VOC abatement<\/a>, our engineering team delivers EU IED\u2013compliant solutions for the most demanding new energy materials emission control requirements.<\/p>\n

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