Pilot to Plant: A Scalable Roadmap for Hydrometallurgy 2.0 in Zinc Recycling

Zinc—one of the most widely used non-ferrous metals—plays a pivotal role in infrastructure, automotive, electronics, protective coatings, and, with the electrification trend, the renewable energy ecosystem. Zinc's corrosion resistance and alloying properties ensure its indispensable status across industries, from galvanizing steel beams to powering batteries for smart devices and vehicles.

Yet the environmental toll of conventional zinc production can no longer be ignored. Traditional zinc mining and refining methods—especially pyrometallurgical processing—consume significant energy and produce greenhouse gas (GHG) emissions at scale. With decarbonization deadlines looming and consumers demanding transparency, the zinc value chain faces mounting regulatory and reputational risks.

Enter Hydrometallurgy 2.0: the next-generation approach that promises to revolutionize zinc recycling by slashing emissions, improving resource efficiency, and opening doors to scalable, flexible operations. In this article, we break down a proven, stepwise roadmap for scaling this breakthrough technology from pilot to commercial plant—outlining essential QA checkpoints, partnership structures, and forward-looking strategies that turn sustainable intent into transformative impact.

The Need for Innovation in Zinc Recycling

The Zinc Challenge

Global zinc consumption surpassed 13 million metric tons in 2023, according to the International Lead and Zinc Study Group (ILZSG). This demand is projected to grow, fueled by surging urbanization, infrastructure upgrades, and the expansion of electric mobility—all core sectors for zinc applications.

However, nearly 80% of zinc still comes from primary mining and energy-intensive smelting—methods that generate some of the highest carbon footprints among non-ferrous metals. Let's break down the sustainability pain points:

Energy Intensity

Pyrometallurgical zinc production—including sintering, roasting, and electrolysis—often consumes over 3,500 kWh per ton of zinc and relies heavily on fossil fuels.

CO₂ Emissions

The World Bank reports that zinc's lifecycle emissions can exceed 3 tons of CO₂ per ton of refined metal, factoring in both direct and indirect emissions.

Resource Inefficiency

Zinc ore bodies are finite. Primary mining not only produces tailings rich in heavy metals, but also decreases ore grades year-over-year, making extraction less efficient and riskier for local environments.

Waste Generation

Slag, sulfur dioxide, and waterborne contaminants must be managed, adding to regulatory and community pressures.

On the regulatory front, governments from the EU to China are ratcheting up Extended Producer Responsibility (EPR), carbon taxes, and mandatory recycled content thresholds. In the private sector, steelmakers and electronics OEMs are embedding recycled zinc into their ESG (Environmental, Social & Governance) scorecards and supply chain audits.

In this climate, zinc's future demands better metals stewardship—a shift from linear resource "take-make-waste" to circular, high-efficiency recovery.

Hydrometallurgy 2.0: What Sets It Apart?

Hydrometallurgy 2.0 signals a clear leap over legacy processes, integrating decades of chemical engineering progress with digital controls and eco-design thinking.

Defining Innovations

- Lower Temperature Operations: Unlike pyrometallurgy, Hydrometallurgy 2.0 operates at <100°C, opening dramatic reductions in both energy use and carbon emissions.

- Enhanced Selectivity: Modern leaching agents and tailored solvent extraction reagents allow zinc to be selectively separated from waste streams teeming with lead, copper, manganese, and other impurities.

- Closed-Loop Processing: Advanced electrowinning and circuit recycling enable both solvent and reagent reuse, slashing the demand for fresh inputs and reducing operational spend.

- Advanced Sensors and Automation: Industry 4.0 tools—such as inline spectrometry, flow chemistry, and AI-driven control—continuously monitor quality, emissions, and material flows, ensuring compliance and minimizing accidents.

- Integrated Emissions Management: Next-gen scrubbers, membrane filtrations, and process water recycling dramatically reduce hazardous releases, maintaining alignment with ever-stricter environmental standards.

Hydrometallurgy 2.0 in Action

These advancements enable economic recovery of zinc not only from traditional sources (like Electric Arc Furnace [EAF] dust or galvanizer residues) but from complex, previously untapped streams—such as battery cathode scraps, plated steel offcuts, and even blended post-consumer electronics.

Industry Stat

According to Wood Mackenzie, such innovations have slashed the zinc sector's specific energy use by over 30% in leading recycling facilities, with GHG reductions nearing 80% compared to pyromet routes.

Roadmap to Scaling: From Pilot to Commercial Plant

Successfully translating hydrometallurgical breakthroughs from benchtop to full-scale production is a nuanced journey. Each phase presents unique risks and demands robust technical, regulatory, and commercial diligence. Here's the proven roadmap underpinning successful scale-ups in the zinc sector:

1. Scoping and Feasibility: Data-Driven Beginnings

Feedstock Characterization

In practice, input streams might include EAF dust, galvanizing ash, spent batteries, and mixed industrial waste. Each source varies in:

- Zinc Concentration (often 5%-40%)

- Impurity Suite (Pb and Cd often exceed EU RoHS thresholds)

- Particle Morphology and Size Distribution

About 300,000 tonnes of EAF dust are generated annually in North America alone—rich in zinc but challenging for legacy pyro-processes.

Conceptual Flowsheet Design

Using the feedstock data, process engineers design several candidate flowsheets, including:

- Batch vs. continuous leaching reactors

- Advanced solvent extraction (SX) versus membrane-based purification

- Emissions scrubbing integrations

Techno-Economic & Environmental Assessment

State-of-the-art modeling tools such as Aspen Plus and GaBi are used to generate high-fidelity forecasts for CAPEX, OPEX, and anticipated environmental benefits (including a cradle-to-gate LCA).

QA Gate 1

A formal technical review evaluates whether the proposed flowsheet can achieve target economics (e.g., $/ton Zn produced), regulatory compliance, and environmental improvements versus baseline.

2. Lab-Scale Validation: Prove the Chemistry

Bench-Scale Experiments

Laboratory runs—using 1-20kg of feed—simulate operating conditions:

- Leaching agents (strong acid, alkaline or organic complexants)

- Time, temperature, agitation rates

- Precipitation of jarosite and stable residue streams

Reagent Selection & Optimization

Focus shifts toward green chemistry: using recycled reagents, biobased solvents, and closed-loop pH control.

Emerging Trend

Bioleaching with specialized bacteria or fungi offers the promise of even further reductions in toxicity and reagent costs.

QA Gate 2

Bench results are scored using rigorous KPIs: zinc yield, impurity rejection efficiency, and reagent consumption rates. Only robust processes—exceeding commercial-in-use targets—progress to the high-stakes, resource-intensive pilot phase.

3. Pilot Plant: Engineering for Reality

Design & Construction

Pilots typically scale inputs to 100-500 kg/day and simulate continuous plant operation:

- Reactors fitted with advanced mixing and temperature sensors

- Multi-stage extraction and purification columns

- Real-time air/water emissions analyzers (meeting ISO 14001 and local standards)

Process Optimization

Pilots stress-test the system with:

- Variable feedstocks mirroring market realities

- Modular setups allowing for reconfiguration (critical for de-risking full-scale investments)

- By-product handling (e.g., iron residues for cement production, or cadmium for battery manufacturing)

Product Specification Testing

Finished zinc—often as high-purity metal or oxide—must meet stringent ASTM/EN standards to qualify for downstream applications in galvanizing, die casting, or zinc-air batteries.

QA Gate 3

Successful pilots maintain steady-state production (often >90 days) of high-purity zinc, tightly controlled emissions, and secure detailed datasets for engineering scale-up.

Scaling Up: From Pilot to Production

Scaling a hydrometallurgical zinc plant from pilot to commercial scale demands careful engineering and data-driven design. In practice, firms conduct iterative pilot tests, gradually increasing flow rates while monitoring kinetics, mixing, and heat transfer. For example, Sherritt Technologies notes that pilot reactors (3–10 kg/h) can inform design of full-scale plants with scale-up ratios up to 25,000:1–125,000:1s2.q4cdn.com. Engineering teams use pilot data and process models to ensure that reactor chemistry and mass transfer remain effective at larger volume. Design considerations include robust mixers, precise temperature control, and contingency for variable feed quality. Risk mitigation often involves a modular or staged ramp-up approach, allowing operators to validate each section of the plant before full throughput.

In summary, scaling up means translating bench chemistry into big equipment: detailed data hand-offs between R&D and EPC (Engineering/Procurement/Construction) firms are critical. Each scaled plant must preserve the Zn yield and purity achieved in pilots while maintaining safety and environmental performance. Rigorous hazard studies and commissioning protocols ensure that larger reactors behave as intended.

Commercialization: Financing and Deployment

Once pilot success is achieved, the next step is commercial deployment – securing capital, permits, and market offtake. Building the first-of-a-kind plant is capital intensive, often requiring hundreds of millions of dollars and extended timelines. Innovative funding mechanisms can accelerate commercialization. For instance, the U.S. Department of Energy (DOE) has supported battery recycling ventures: Redwood Materials and GM/LG's Ultium Cells were selected for DOE loan guarantees under the Advanced Technology Vehicles Manufacturing programredwoodmaterials.com. Such public-private funding helps overcome early investment barriers and validates emerging tech.

Speed to market can be rapid for hydrometallurgy. Redwood Materials reports that it built and activated its Nevada recycling plant in "less than a quarter" of the typical timeline for a new mineredwoodmaterials.com. The plant converts EV battery scrap into nickel, cobalt, lithium and copper outputs, underscoring how hydrometallurgical plants are commercialized on a faster schedule than traditional mining projects. Additionally, strategic off-take agreements with manufacturers (e.g. OEMs committed to using recycled metals) can de-risk financing. Clear demonstration of environmental benefit – such as life-cycle CO₂ analyses – also bolsters project economics and investor confidence. Altogether, successful commercialization combines proven pilot results with supportive policy, innovative financing, and committed customers.

Partnerships: Building a Recycling Ecosystem

Strategic collaborations are key to scaling recycling. OEMs, recyclers, and tech firms increasingly form partnerships that tie waste sources to recycling capacity. In the automotive sector, leading examples include GM/LG Ultium Cells partnering with Redwood Materials – Redwood now recycles production scrap from GM's Ohio and Tennessee gigafactoriesredwoodmaterials.com. Similarly, Stellantis (Peugeot/Chrysler) and nuclear firm Orano have launched a joint venture to recycle EV battery packs into "black mass" feedstock for new cellsverifiedmarketreports.com. Such alliances ensure a steady supply of scrap and a guaranteed buyer for the recycled metals.

Beyond automakers, pure recyclers and material companies also form consortia. For example, BASF's battery recycling arm operates a 15,000-ton-per-year black-mass plant in Germany in partnership with Stena Metall, providing recovered cobalt, nickel and lithium to Europe's battery industryampedautomagazine.com. Mercedes-Benz teamed with Primobius to open one of Europe's first integrated recycling plants, achieving >96% recovery of key battery metalsampedautomagazine.com. In North America, partnerships span supply chains – Ford has invested in Redwood, Toyota is collaborating on battery collection and recycling, and Glencore-owned Li-Cycle works with utilities and manufacturers to source battery scrapampedautomagazine.com.

These examples highlight that no single company owns the solution. Joint R&D consortia (linking universities, engineering firms and recyclers) also refine new processes. Governments often join these efforts via grants or mandates (e.g. extended producer responsibility laws). Together, such partnerships create the scale, expertise and market certainty needed to bring hydrometallurgical recycling technologies fully to market.

Quality Assurance and Compliance

Rigorous QA/QC underpins every scaled facility. Ensuring the final zinc product (and co-product metals) meets industry specs requires multiple layers of control. At the front end, material inspection and sorting remove hazardous or off-spec components. In practice this often involves manual sorting lines and automated sensors. For example, workers at recycling plants visually inspect shredded battery and metal waste on conveyor tables (as shown below), removing plastics, wires, or damaged cells before leaching. This frontline sorting step is critical to achieve consistent feed compositionokonrecycling.com.

Teams of operators sort mixed battery and metal scrap by hand (with protective gear) before chemical processingokonrecycling.com. Each batch or run is then monitored by inline and lab analytics: pH, redox potential, and metal concentrations (via ICP or XRF) are tracked closely. Recovered zinc is precipitated or electrowon to tight purity standards (ASTM B6 zinc grades, for example), so contaminant metals like lead or cadmium must be controlled. Emissions are continuously monitored to meet air/water permits. Leading facilities implement formal quality/environmental management systems – for instance, Redwood's Nevada plant is ISO 14001 (environmental) and ISO 45001 (safety) certifiedredwoodmaterials.com. In short, a culture of QA means systematic testing at each stage, staff training, and transparent reporting, so that customers can trust recycled zinc and other metals to meet the same specifications as virgin materials.

Case Studies: Real-World Success Stories

Several projects illustrate hydrometallurgy 2.0 in action. Redwood Materials (USA) is a high-profile example: as of 2024 it was processing ~60,000 tons of batteries and scrap per year, generating ~$200 million in material salescanarymedia.com. Its Nevada campus (shown below) functions as a "battery raw materials park." Cell packs are shredded into black mass, then subjected to multi-stage leaching and electrowinning to yield high-purity nickel, cobalt, lithium and copper. Notably, Stanford researchers reported Redwood's process emits ~40% fewer greenhouse gases than competing approachesredwoodmaterials.com.

Aerial view of Redwood Materials' Nevada recycling complex, which can process ~60,000 tonnes of EV battery waste annuallycanarymedia.com.

EcoRecycling SRL (Italy) and partners have advanced battery hydrometallurgy in Europe. In one demonstration, a bioleaching plant using Acidithiobacillus bacteria extracted 100% of the zinc and 67% of the manganese from spent alkaline/Zn-carbon battery powderscielo.org.ar. EcoRecycling and Sapienza University even patented the first Italian plant for spent Zn-battery recyclingscielo.org.ar, showing that biological methods can be viable at scale.

Sherritt Technologies (Canada) provides a long-standing example for zinc metal. Its zinc pressure-leach (ZPL) process has been commercialized in nine plants worldwides2.q4cdn.com, treating both concentrates and complex wastes. These facilities convert various oxides and ferrites into zinc sulfate solutions for electrowinning. Sherritt's experience demonstrates that hydrometallurgical zinc recovery is proven technology, now being updated with modern automation.

Industrial Partnerships: In Germany, BASF's recycling unit, in joint venture with Stena Metall, operates a 15,000-ton/year lithium-ion battery recycling plant using hydrometallurgyampedautomagazine.com. Mercedes-Benz and Primobius opened a 20,000-ton battery recycling plant at Kuppenheim, achieving over 96% recovery of cobalt, nickel, manganese, and lithiumampedautomagazine.com. In Asia, Chinese firm GEM's $239 million Yibin facility will process 100,000 tons per year of decommissioned batteries via hydrometallurgyverifiedmarketreports.com. India's BatX Energies similarly inaugurated a 100,000-ton-per-year Li-ion recycling plant (HUB-1) using proprietary hydroprocessingverifiedmarketreports.com. These case studies across continents show the viability of hydrometallurgical zinc (and base metal) recycling from multiple feedstocks – from steel mill dust and galvanizer ash to the rapidly growing volumes of battery waste.

Future Trends in Hydrometallurgical Recycling

Looking ahead, several trends are shaping the next wave of technology and strategy. Industry-wide, digitalization and automation will accelerate. For instance, advanced robotics and AI-driven systems are being added to disassembly and sorting lines, making recycling faster, safer and more preciseampedautomagazine.com. "Direct upcycling" concepts—where cathode materials are reconstituted without fully breaking them down to base metals—are emerging, potentially saving energy and stepsampedautomagazine.com. On the chemistry side, green biotechnologies are gaining ground: bioleaching offers a low-energy, non-toxic route to dissolve metals. Microbes and fungi can target zinc and other metals using mild acids or chelators. In fact, bioleaching is praised as a "green technology" requiring low energy, no toxic waste, and low capital costsmdpi.com. We expect R&D to focus on engineered microbes or biogenic reagents that can selectively recover metals with minimal environmental impact.

Environmental integration is also key. Many new plants aim to run on renewable energy – some facilities already use solar power to drive their hydrometallurgical circuitsokonrecycling.com. Heat integration, water recycling and carbon capture may become standard in future designs. Materially, as carbon accounting gets stricter, recycled zinc (and copper, nickel, etc.) with a very low CO₂ footprint will command price premiums.

Finally, policy and circular-economy mandates will continue to strengthen. Higher recycled-content requirements and carbon taxes in Europe, North America and Asia will further tip the balance in favor of hydrometallurgical recycling over primary smelting. Overall, the convergence of digital tools, green chemistry, renewable energy, and supportive regulations promises that Hydrometallurgy 2.0 will only get more efficient, scalable, and economically attractive in the years aheadokonrecycling.comampedautomagazine.com.

Sources

Industry reports and peer-reviewed studies on metallurgical recyclings2.q4cdn.comokonrecycling.comverifiedmarketreports.comscielo.org.arredwoodmaterials.comampedautomagazine.com provide data on commercial facilities, partnerships, and future directions in sustainable zinc and base-metal recovery.