Lined Pipe for Battery and Lithium Plants

Battery chemistry is hydrometallurgy with a purity spec. Lithium is leached from rock and clay with hot sulfuric acid and converted with caustic, cathode precursor is precipitated from metal sulfates with caustic and ammonia, electrolyte salt is made from anhydrous hydrofluoric acid, and spent cells are leached back to sulfate with acid and peroxide. All of it corrodes steel, and a few parts per million of iron, copper or zinc from a pipe wall is a rejected lot. Marspec Technical Products fabricates PTFE-, PVDF- and polypropylene-lined steel pipe spools and supplies the lined fittings, valves and accessories for that work, with spools shipping nationwide from Fairhope, Alabama. Call (251) 625-4949 or contact us online.

The processes may be unfamiliar to a plant; the chemistry is not, and we have lined pipe for it for more than half a century.

Where the corrosive streams are in a battery supply chain

Brine, rock and clay to lithium salts

Brine operations concentrate lithium in evaporation ponds, strip magnesium and calcium with lime and soda ash and precipitate lithium carbonate; direct lithium extraction loads lithium onto a sorbent from hot, high-chloride brine and strips it with dilute hydrochloric acid. Hard-rock plants calcine spodumene, roast it with 93 to 98 percent sulfuric acid near 250 °C, leach the roast with water to a lithium sulfate liquor, and clean that liquor with lime, caustic, soda ash and ion exchange regenerated with hydrochloric acid and caustic. Causticizing with 50 percent caustic gives lithium hydroxide, crystallized in vacuum evaporator-crystallizers while sodium sulfate is removed as Glauber's salt by cooling. Clay projects leach with sulfuric acid from an on-site acid plant and neutralize with limestone and lime. Lined pipe starts after the kiln, because the acid roast runs near 250 °C, above PTFE's 450 °F (232 °C) limit: the water leach, leach liquor, lithium sulfate and caustic liquors are PTFE service, and chloride brine is PTFE or PVDF service, with polypropylene available for the cooler liquors and brine where a specification calls for it; the sulfuric acid, caustic soda and brine pages give the limits, and our mining and metals page covers the front end.

Cathode, anode and electrolyte

A precursor plant dissolves nickel, cobalt and manganese sulfate, feeds the solution to stirred reactors with caustic and aqueous ammonia at a pH around 11 and about 60 °C, and co-precipitates a mixed hydroxide that is filtered, washed with deionized water and dried before lithiation. Sodium sulfate leaves in the filtrate and is crystallized for sale, and ammonia vented from the reactors is scrubbed with sulfuric acid. Iron phosphate for LFP cathode starts from ferrous sulfate, phosphoric acid and hydrogen peroxide. Transition metal impurities degrade the cell, so the specification is written around what the piping must not add: PTFE-lined spools and PFA-lined valves put no iron, nickel or chromium into the sulfate feed, the caustic or the wash water. Aqueous ammonia is PTFE service: amines and caustic attack PVDF, and we prefer PTFE for ammonia.

Anode graphite is purified by acid leaching, often with hydrofluoric and hydrochloric acid, or by caustic roasting. The electrolyte is lithium hexafluorophosphate in carbonate ester solvents, and the salt is made from anhydrous hydrofluoric acid; parts-per-million moisture hydrolyzes it back to HF, which is why electrolyte lines are dry, nitrogen-blanketed and metal-free. Carbonate esters and the N-methylpyrrolidone used to coat cathodes attack PVDF, so solvent recovery, electrolyte transfer and the caustic scrubbers that catch HF and solvent vapors are PTFE- and PFA-lined service. The carbonate solvents can build a static charge that pinholes a plain lining or ignites vapor, so bond and ground the spools and use anti-static PFA-AS valves; tell us if your specification calls for an anti-static liner. Our solvents and hydrofluoric acid pages explain the limits.

Recycling

A hydrometallurgical recycler shreds cells, screens out black mass and leaches it in sulfuric acid with hydrogen peroxide at 60 to 90 °C, removes iron, aluminum and copper by pH adjustment and solvent extraction, and precipitates nickel, cobalt, manganese and finally lithium carbonate with soda ash. The leach liquor carries fluoride from the electrolyte, which rules out glass and stainless and makes PTFE or PVDF the liner; loaded organic from solvent extraction is PTFE service. Lead-acid recyclers neutralize battery acid and desulfurize paste with caustic or soda ash, a PTFE job, run within velocity limits, with lined diaphragm valves for the slurry.

Liner by stream

• Hot sulfuric acid leach and black mass liquor, fluoride-bearing liquor, loaded organic, NMP and carbonate solvents, HF: PTFE, with PFA-lined valves
• Spodumene slurry and lithium carbonate slurry: PVDF, the hardest, most abrasion-resistant of the three liners; deionized wash water and polisher water: PTFE, with PVDF an option on utility deionized water; see our high-purity water page
• Caustic at 32 and 50 percent, lithium hydroxide and lithium sulfate liquor, precursor slurry, soda ash, sodium sulfate, aqueous ammonia and dilute raffinate: PTFE, with polypropylene available where a specification calls for it
• Abrasive acidic or neutral slurries: PVDF with lined diaphragm or plug valves (caustic and ammonia slurries need PTFE), as our slurry and abrasive service page explains

The package

Custom lined spools from 1/2" through 12" and up to 20 ft, fabricated to your isometric with lined elbows, tees, reducers and instrument tees that conform dimensionally to ANSI B16.5, in carbon steel or 304 and 316 stainless housings; stainless housings are the usual choice inside dry rooms and precursor buildings where the outside of the pipe has to stay clean. Evaporator-crystallizers and solvent recovery stills run under vacuum, so tell us the vacuum and temperature on those lines and we will select the liner by size; liner temperature limits, liner thicknesses, flange dimensions and torque tables are on our technical details page.

PFA-lined ball and plug valves give metal-free shutoff on sulfate feed, acid and solvent; lined diaphragm valves handle precursor, carbonate and black mass slurries; lined check valves sit at reagent pumps; and lined sampling valves draw leach liquor for assay without exposing an operator. We assemble automated packages, actuators, positioners and switches mounted and tested, for reagent dosing that runs on pH control. See our lined valves page.

Lined strainers, sight glasses, PTFE spacers and spectacle blinds, PTFE-bellows expansion joints and dip pipes and spargers for leach and precipitation tanks are on our piping accessories page. Temperature maintenance matters more here than in most plants: ethylene carbonate is a solid below about 97 °F (36 °C), sodium sulfate crystallizes as the decahydrate once a line cools below roughly 90 °F (32 °C), lithium hydroxide drops out of a cooling solution, and 50 percent caustic crystallizes near 54 °F (12 °C). We supply steam-jacketed lined pipe and fittings, clamp-on steam heaters, electric tracing and heat-transfer compound from our temperature maintenance line, matched to the liner's limit.

Where the industry is

Nevada has the only producing lithium brine operation in the country at Silver Peak and cell and recycling plants at the Tahoe-Reno Industrial Center. The Carolina tin-spodumene belt around Kings Mountain in North Carolina is one of the largest hard-rock lithium deposits in the country, with a cell plant at Liberty and recycling at Ridgeville in South Carolina. Cell plants run at Lansing, Holland and Marshall in Michigan, a lithium hydroxide refinery operates at Robstown in Texas, and the Salton Sea brine in California and the Smackover brine of Arkansas are the direct extraction frontier.

Standards and a quote

Our lined pipe and fittings comply with ASTM F1545, fittings conform dimensionally to ANSI B16.5 and are welded to ASME B31.3 by welders certified to ASME Section IX, and every lined spool and fitting passes a minimum 10,000-volt spark test before it ships. Many of these flowsheets are first-of-a-kind, so send the stream list with concentrations, temperatures, solids and the purity limits that matter, and we will confirm a liner for each line and quote spools, valves and accessories together. Call (251) 625-4949 or contact us online. Custom spools fabricated in our own shop ship nationwide from Fairhope, Alabama.

FAQ: Lined Pipe for Battery and Lithium Plants

Which liner do you recommend for the sulfuric acid leach and lithium sulfate circuit at a conversion plant?

PTFE throughout: for the leach of the acid roast, where temperature and concentration are highest (the kiln itself runs above any liner's limit), and for the cooler lithium sulfate liquor, lime and soda ash streams after impurity removal. Polypropylene is available for those cooler streams where a specification calls for it. Tell us the temperature and solids at each step and we will mark up the line list.

Can lined pipe carry NMP and carbonate electrolyte solvents without contaminating them?

PTFE-lined pipe and PFA-lined valves can. Both solvents attack PVDF, and the electrolyte cannot tolerate moisture or metal ions, so we supply PTFE-lined spools, bonded and grounded because the carbonate solvents can build a static charge, with anti-static PFA-AS valves, and recommend nitrogen blanketing and dry assembly on the electrolyte side.

Will a lined system keep iron and copper out of cathode precursor feed and wash water?

Yes. The liner is the only wetted surface, and PTFE, PFA and PVDF contribute no transition metals. We recommend PTFE for the deionized wash water, with PVDF an option there, and for the sulfate feed, caustic and ammonia, with PFA-lined valves throughout.

Is fluoride in black mass leach liquor a problem for lined pipe?

Not for fluoropolymer liners. Fluoride rules out glass-lined equipment and pits stainless, but PTFE and PVDF are unaffected by fluoride-bearing sulfuric acid at leach temperatures. We supply lined diaphragm and plug valves for the slurry.