Lithium Refinery Corrosion: Where FRP Fits, Step by Step

In short: A spodumene-to-lithium refinery runs hot kilns, concentrated sulfuric acid, acid mist, salt solutions and strong caustic in one plant. FRP has no place in the 1,100 °C calciner or the 250 °C acid roast itself, but it is a common choice downstream: off-gas scrubbing, leach and liquor tanks, dilute acid and brine piping, and walkways in wet areas. The resin must change with the step, because the same plant is acidic at one end and strongly alkaline at the other. This guide walks the process step by step and shows where FRP fits, where it does not, and what to send us for a custom quote.

How this guide fits with our others

This is the process-step corrosion map for lithium refineries. For acid exhaust, scrubbers and chemical tanks in wafer fabs, where fire rules decide more than corrosion does, read FRP in semiconductor fabs: exhaust ducts, scrubbers and tanks. Copper and nickel leach and electrowinning plants are covered in FRP in mining and metal refining. Other sectors are on our industries page and emerging industries page.

The two main routes to battery-grade lithium

Lithium chemicals come from two main sources: hard rock, mostly spodumene concentrate, and brines.

Hard rock (spodumene). Pall's application paper on spodumene refining describes the conventional sequence:

1. Calcination (decrepitation) at about 1,100 °C, which changes the crystal structure and opens the mineral to extraction.
2. Acid roast with sulfuric acid at about 250 °C, then neutralizing and water leaching, which puts the lithium into a lithium sulfate solution.
3. Solids and impurity removal: a sand filter and cartridge filters, chemical precipitation of unwanted metals and a filter press.
4. Concentration in a multiple-effect evaporator, then ion exchange to remove divalent ions such as calcium and magnesium.
5. Conversion: sodium carbonate is added, forming lithium carbonate and leaving sodium sulfate in solution, followed by vacuum crystallizers, centrifuges and a second crystallization stage.

A review of roasting processes in Metals (2020) adds two useful limits. The acid roast must stay below about 337 °C to avoid evaporating the acid, and lime precipitation at about 90 °C is used to adjust pH and remove impurities after leaching. For lithium hydroxide, a technical bulletin from the Australian piping supplier SPFA describes a further step: the lithium sulfate is reacted with sodium hydroxide to form lithium hydroxide and sodium sulfate. The Albemarle Kemerton plant documents list dryers and coolers for the hydroxide product.

Brines. The USGS deposit model describes brine carrying 200–1,400 mg/L lithium, pumped to a chain of evaporation ponds and concentrated over a few months to about a year to a 1–2% lithium concentrate, which a chemical plant turns into carbonate or other products. Direct lithium extraction (DLE) replaces the ponds with sorption, ion exchange, solvent extraction, membranes or electrochemical steps. A report in the US DOE OSTI repository notes that DLE can work in hours and that the spent brine can be reinjected.

Corrosion by step: where FRP fits

The table below maps each step to its main corrosive or thermal load and to the role, if any, that FRP can play.

1. Kilns and roasters: not an FRP job

Be clear about this first. At about 1,100 °C in the calciner and about 250 °C in the acid roaster, no polyester or vinyl ester laminate is suitable; these temperatures are far above the service limits in our FRP temperature limits by resin type. Kiln shells, burners and hot dust filters stay metal and refractory.

The Albemarle Kemerton air quality assessment shows how these units vent: the calciner flue passes through gravity separation, cyclones and a bag filter, and the acid roast kiln is indirectly heated so the combustion gas stays separate from the process gas. FRP becomes relevant only once the gas has cooled and become wet.

2. Acid roast off-gas: the main scrubber duty

The same Kemerton assessment states that process off-gas from the acid roast kiln contains sulfuric acid mist and sulfur trioxide (SO3), and is scrubbed in four stages:

1. Venturi
2. Packed tower with water
3. Packed tower with sodium hydroxide
4. Electrostatic precipitator (ESP)

This is a classic place for FRP. FM Global's data sheet on industrial exhaust systems notes that in corrosive environments FRP is common for gas cleaning plants and air pollution control systems, because of manufacturing flexibility and the option of making the supporting structure from the same material.

The resin needs care at both ends of this train:

• Concentrated acid. A resin manufacturer's FRP Material Selection Guide explains that dilute sulfuric acid is handled well by FRP, but above about 76% the acid becomes more aggressive, and SO3 can dehydrate polyesters and vinyl esters to a charred surface. It also notes that where SO3 is present, the first drop that condenses can contain up to 82% sulfuric acid. Where condensate can collect in a duct low point or a sump, design it to drain and dilute quickly.
• Caustic stage. The sodium hydroxide tower and its sump see strong alkali. The same guide says isophthalic and terephthalic polyesters should not be used continuously above about pH 10.5, recommends bisphenol-A polyester or bisphenol-A epoxy vinyl ester resins for alkaline service, and cautions that novolac vinyl esters can fail in strong bases at high temperature. A synthetic surfacing veil is common in alkaline service.

Our packed bed scrubber sizing guide and mist eliminator guide cover the internals. We do not supply ESPs or venturi throats; the plant designer or scrubber licensor sets those.

3. Leach, filtration and impurity removal

After the roast, the solids are leached with water and neutralized. That gives warm acidic or near-neutral slurries and salt solutions full of silica, alumina residue and precipitated impurities.

• Tanks and launders. FRP tanks suit lithium sulfate liquor, filtrate and dilute acid, provided the resin is chosen for the actual pH range and temperature. Tell us the liquor analysis, including any free acid and the highest temperature at start-up.
• Abrasion. Slurry with tailings solids wears any lining. For impinging hard particles, the same manufacturer's guide reports good results from about 30% silicon carbide grit or ceramic beads in the surface; for sliding abrasion, from synthetic (nylon or polyester) or carbon veils. We agree the wear layer per project.
• Lime step. The Metals review cites lime precipitation at about 90 °C. Check that temperature against the resin's limit in our temperature guide before choosing FRP; it is a resin-selection decision, not a default FRP item.

Pall places ion exchange after the evaporator to remove calcium and magnesium. If you want FRP vessels or pipes around the ion exchange step, tell us every chemical they will see, including regeneration and cleaning chemicals. Where a vessel sees both acid and caustic, we size the resin and veil to the harsher duty.

4. Evaporation, crystallization and conversion

Pall describes multiple-effect evaporators and vacuum crystallizers for the carbonate product. These are pressure- and vacuum-rated vessels with tight temperature control, usually in alloy. FRP has a role around them rather than in them:

• condensate and mother liquor tanks;
• process water and cooling water pipes;
• FRP grating and handrail on wet platforms around centrifuges and filters.

For the hydroxide route, the Kemerton documents list wet spray scrubbers on the lithium hydroxide monohydrate dryer and cooler vents. Those scrubbers see alkaline dust and vapor, so they need the same alkaline-resistant resin choices as the caustic tower above.

5. Brine ponds and DLE plants

Brine operations bring high chloride levels, which matter for metals. SSINA notes that chloride stress corrosion cracking of austenitic stainless steel is rare below about 60 °C when fully immersed, but evaporative conditions can cause cracking well below that, which can apply around brine ponds and spray areas. For FRP, the resin must suit the brine and any reagents.

Typical FRP items at brine and DLE sites:

• brine and process water pipes and fittings;
• regenerant and reagent tanks;
• cable trays and supports in salt-laden air;
• walkways and stair treads over pond inlets and pump stations.

DLE sorbent or ion exchange columns in FRP are custom / available on request. The process licensor sets the internals, so we build the shell and nozzles to their data sheet.

Honest limits of FRP in a lithium plant

FRP is not the answer everywhere in this plant:

• Temperature. Kilns, roasters, hot dryers and many evaporator bodies are outside FRP's range.
• Concentrated sulfuric acid. Above about 76%, the same manufacturer's guide says sulfuric acid becomes more aggressive to FRP; very strong acid and oleum are often handled in carbon steel or alloys instead.
• Fire. FM Global's industrial exhaust data sheet states that FRP ducts and liners can support fire spread and sets fire protection recommendations for combustible exhaust systems. Check your insurer's requirements before you choose FRP ducts.
• Abrasion. Slurries wear the corrosion barrier; plan inspection and wear allowances.
• Static. The same manufacturer's guide notes that large FRP equipment can build static charge and describes a grounded carbon veil as one remedy. Tell us if the area is classified.

These limits decide which items should be FRP and how they are built.

Material choices, side by side

The SPFA bulletin, for comparison, names high-nickel Alloy 20 or Alloy 31 as likely materials in sulfuric acid leaching and 304L stainless for lithium hydroxide refining. FRP competes with those alloys only where the temperature and concentration allow it.

What to send for a quote

1. Process step and P&ID or equipment list.
2. Liquor or gas analysis: acids, caustic, chlorides, sulfate, solids.
3. Normal, upset and cleaning temperatures.
4. Pressure or vacuum, and any agitation.
5. Sizes, nozzles and supports, or a data sheet.
6. Fire, static and hazardous-area requirements.
7. Required tank standard. We can build tanks to ASTM D3299-26 (filament-wound or contact-molded) or to a specification based on ASME RTP-1. That is a design basis only, not an ASME stamp.

See our tank data sheet checklist and FRP chemical resistance guide.

How we customize for lithium projects

Every item is built to your process data: resin per step (isophthalic for mild duty, bisphenol-A or novolac vinyl ester by acid and temperature, synthetic or carbon veil where needed), wall thickness, nozzle layout, manways, lifting lugs and color. Acid fume scrubbers, storage tanks, pipes and grating are standard ranges built to size. DLE columns, large field-joined tanks and special ducts are custom / available on request. Read custom FRP manufacturing for how an order runs.

We do not claim any certificate or third-party approval for lithium service. Tell us your project's requirements and we will state which tests and records we can supply.

Dust, mist and VOC equipment

Calcining and drying lines create dust; leaching and acid areas create mist; electrode coating creates solvent VOCs. Matching equipment: baghouse dust collectors, wet ESPs and RTOs.

Watch: Battery Plant Emissions in 27 Seconds

FAQ

Can FRP be used in a lithium acid roast kiln?

No. The roast runs at about 250 °C and the calciner at about 1,100 °C, far above FRP's limits. FRP is used downstream, after the gas has cooled.

What is in the acid roast off-gas?

The Albemarle Kemerton assessment lists sulfuric acid mist and SO3, treated by a venturi, a water packed tower, a caustic packed tower and an ESP.

Which resin suits the caustic scrubber?

Bisphenol-A polyester or bisphenol-A epoxy vinyl ester, per the same manufacturer's guide, usually with a synthetic veil. Avoid isophthalic polyester above about pH 10.5.

Is FRP used at brine and DLE sites?

Yes, for pipes, tanks, cable trays and walkways in chloride-rich air. DLE columns are custom / available on request.

How is this different from a copper refinery?

Copper plants center on leach, solvent extraction and electrowinning. Lithium plants add kilns, an acid roast and a strongly alkaline hydroxide end. See our mining and metal refining guide.

Sources

• Pall Corporation, Lithium refining: hard rock to lithium carbonate (calcination 1,100 °C, acid roast 250 °C, evaporator, ion exchange, crystallizers): https://www.pall.com/content/dam/pall/chemicals-polymers/literature-library/non-gated/application-notes/lithium-processing-hardrock-to-lithium-carbonate.pdf
• Literature Review and Thermodynamic Modeling of Roasting Processes for Lithium Extraction from Spodumene, Metals 2020, 10(10), 1312 (below 337 °C; lime precipitation at 90 °C): https://www.mdpi.com/2075-4701/10/10/1312
• Albemarle Kemerton Plant Air Quality Impact Assessment, Part A, 2017, via WA EPA (calciner flue, acid roast off-gas stages, LiOH dryer and cooler scrubbers): https://www.epa.wa.gov.au/sites/default/files/Referral_Documentation/CMS17244%20-%20Appendix%20F%20-%20Albemarle%20Kemerton%20Plant%20Air%20Quality%20Impact%20Assessment%20Part%20A%20from%20Albemarle%207%20November%202017%20%28DWERDA-013528%29.pdf
• USGS Open-File Report 2013-1006, A preliminary deposit model for lithium brines (200–1,400 mg/L; ponds; 1–2% concentrate): https://pubs.usgs.gov/of/2013/1006/OF13-1006.pdf
• DOE OSTI report 1891626 on direct lithium extraction (DLE methods, hours, reinjection): https://www.osti.gov/servlets/purl/1891626
• A resin manufacturer, FRP Material Selection Guide, 2009 (sulfuric acid above 76%, 82% first condensate, alkaline resins, pH 10.5, veils, abrasion, static)
• FM Global Property Loss Prevention Data Sheet 7-78, Industrial Exhaust Systems (FRP in corrosive gas cleaning; fire spread in plastic ducts): https://www.fm.com/FMAApi/data/ApprovalStandardsDownload?itemId=%7B9832E070-0CDF-4B1F-87F7-357F3902B707%7D
• SSINA, Chloride Stress Corrosion Cracking (rare below about 60 °C when fully immersed; lower under evaporative conditions): https://www.ssina.com/education/corrosion/chloride-stress-corrosion-cracking/
• SPFA Technical Bulletin T0001, Lithium extraction (Li2SO4 + NaOH to LiOH; Alloy 20 or 31 in sulfuric leach; 304L in LiOH refining): https://www.spfa.com.au/wp-content/uploads/2024/12/SPFA_Technical_Bulletin_T0001_v1_01_Lithium_Extraction.pdf
• ASTM D3299-26, Filament-Wound and Contact-Molded Glass-Fiber-Reinforced Thermoset Resin Corrosion-Resistant Tanks: https://store.astm.org/d3299-26.html