Nitric Acid for CRT Phosphor Rare Earth Recovery

Discarded cathode-ray-tube phosphor powder can contain yttrium and europium together with zinc, glass fines, coatings and regulated constituents. Those secondary resources are compositionally different from fluorescent-lamp phosphors and require careful separation before hydrometallurgy. Nitric acid has been selected in recent research because nitrate chemistry can support leaching and later rare-earth precipitation without introducing sulfate or chloride into the circuit. A useful flowsheet must still control dust and lead-bearing fractions, quantify co-dissolved zinc, close the rare-earth balance and prove that the recovered oxide or oxalate meets a buyer’s specification. A single extraction percentage does not establish an industrial process.

For B2B implementation, assign owners in process engineering or laboratory management, quality, purchasing and EHS before the first delivery. Approve receiving tests, sampling tools, storage, dosing or analytical basis, deviation response and retained-sample period in writing. Compare representative nitric acid lots under identical conditions and record mass balance or analytical recovery, product quality, waste load, emissions and equipment observations. Define who may approve a temporary deviation and what evidence is required before release. Review transportation, package integrity, unloading, ventilation and emergency response alongside the supplier’s laboratory results. Close each qualification with a written conclusion, an updated material specification and defined requalification triggers. Procurement should confirm lead time, minimum order, container loading, port documentation and contingency stock. Quality teams should trend incoming results instead of recording only pass or fail, while users record actual consumption and performance. Before scale-up or routine adoption, repeat the trial at expected load, residence time and recycle ratio. Sample startup, stable operation and shutdown because transient conditions can reveal corrosion, impurity or filtration problems. Document calibration, detection limits and calculation formulas so results can be reproduced. Include raw material, utilities, labor, maintenance, emissions control, waste treatment and inventory in the economic review. This disciplined approach separates acid-lot variation from feed, equipment, matrix or operating changes and supports faster buyer-supplier investigations. Confirm unloading connections, storage capacity and segregation from incompatible materials through a documented site review. Train operators on the current safety data sheet, exposure controls, first response and notification routes. Audit scales, flowmeters or pipettes used to dose acid, because concentration control cannot compensate for inaccurate addition. Review results jointly with the supplier before approving a long-term specification, and keep the agreed test methods attached to the purchase contract. Where recycled process liquor is involved, distinguish fresh-acid consumption from total circulating inventory. Schedule periodic requalification after equipment, packaging, raw-material source or process changes. These additional controls make performance evidence transferable from development into routine purchasing and production.

Build a representative CRT phosphor feed

Separate screen type, glass fraction, coatings and phosphor powder using an approved dismantling and dust-control plan. Analyze yttrium, europium, zinc, lead and other rare earths on multiple composites because historical tubes and collection sources vary.

Define the recovery objective

Specify the acceptable mixed rare-earth product, oxide purity, zinc limit, recovery, residue classification and downstream refining route before choosing acid concentration or solid-to-liquid ratio.

Use recent research as a trial boundary

A 2026 Separation and Purification Technology study evaluated nitric-acid leaching of CRT phosphors followed by oxalic-acid precipitation. It showed that selectivity and zinc behavior depend on conditions.

Design a factorial screening program

Vary acidity, temperature, time and solids loading with duplicates and more than one feed lot. Measure pH, dissolved metals and filtration behavior throughout the run rather than copying a single published setting.

Track every rare-earth and zinc stream

Analyze feed, leach residue, pregnant solution, washes, precipitate and calcined product. Account for solution held in filter cake. Report extraction, precipitation yield and final recovery separately.

Control precipitation and product washing

Establish oxalic acid addition, mixing, aging, temperature and washing endpoints with representative nitrate liquor. Characterize particle size, filterability, entrained zinc and nitrate before calcination or sale.

Engineer emissions, materials and waste

Use closed acid dosing, temperature control, compatible ventilation and NOx scrubbing approved by qualified engineers. Confirm materials for nitric acid, dissolved metals and abrasion from glass fines.

Manage CRT-specific hazards

Provide enclosure, local exhaust and authorized routes for leaded glass, phosphor dust, spent liquor and filter solids. Demonstrate that recovery reduces total environmental burden instead of transferring contaminants to a new residue.

Qualify nitric acid for repeatable leaching

Specify concentration, assay, chloride, iron, residue and relevant trace metals. Require agreed methods, lot COA, packaging, seals, retained samples and change notification. Compare representative acid lots in the same test.

Prepare a phased supply inquiry

Share concentration, trial volume, package, destination and impurity limits. Review the Hiacid nitric acid product page, then request documented trial and commercial supply.

Related nitric acid resources

Frequently asked questions

Does nitric acid selectively recover all CRT rare earths?

No. Feed mineralogy and operating conditions affect yttrium, europium, zinc and other elements differently.

Why measure zinc during precipitation?

Zinc can co-precipitate or contaminate the rare-earth product and lower its value.

Can a leaching result be reported as final recovery?

No. Final recovery includes precipitation, washing, calcination and product acceptance losses.

What belongs in the nitric acid specification?

State concentration, assay, chloride, metals, residue, methods, packaging, traceability and change control.

Nitric Acid for Rare Earth Recovery from CRT Phosphors