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, shipping nationwide from Fairhope, Alabama. Call 251-625-4949 or contact us online.

The processes are new to many plants; 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. Hot acid roast slurry, 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- or PFA-lined spools and lined valves put no iron, nickel or chromium into the sulfate feed, the caustic or the wash water. Aqueous ammonia is PTFE service, never PVDF, which amines attack.

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; 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 with lined diaphragm valves for the slurry.

Liner by stream

• Hot sulfuric acid roast, leach and black mass liquor, fluoride-bearing liquor, loaded organic, NMP and carbonate solvents, HF: PTFE or PFA
• Spodumene and precursor slurries, lithium carbonate slurry, deionized wash water and polisher water: PVDF, the strongest liner and the one that sheds nothing into high-purity water; see our high-purity water page
• Caustic at 32 and 50 percent, lithium hydroxide and lithium sulfate liquor, soda ash, sodium sulfate, aqueous ammonia and dilute raffinate: PTFE, with polypropylene available where a specification calls for it
• Abrasive slurries of any chemistry: PVDF with lined diaphragm or plug valves, 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 those spools are selected by size and liner from the ratings on our technical details page, and PTFE housings are vented where hot acid or HF permeation is a concern.

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, sodium sulfate crystallizes as the decahydrate once a line cools below roughly 90 °F, lithium hydroxide drops out of a cooling solution, and 50 percent caustic crystallizes near 54 °F. 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, the clay leach project at Thacker Pass with its own acid plant, and cell and recycling plants at the Tahoe-Reno Industrial Center. The Carolina tin-spodumene belt around Kings Mountain in North Carolina is the largest hard-rock lithium deposit in the country, with a cell plant at Liberty and recycling at Ridgeville in South Carolina. Cell plants run or are being built in Bryan County outside Savannah, at Glendale and Bowling Green in Kentucky and 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 products 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 part 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 hot acid roast slurry and leach, where temperature and concentration are highest, 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- and PFA-lined pipe and valves can. Both solvents attack PVDF, and the electrolyte cannot tolerate moisture or metal ions, so we supply PTFE-lined spools with PFA-lined 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. For deionized wash water we recommend PVDF, and for the sulfate feed, caustic and ammonia PTFE, 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 vent the housings on hot lines and supply lined diaphragm and plug valves for the slurry.