Detailed Explanation of Main Processes and Procedures for Titanium Scrap Recycling
Titanium boasts high strength, excellent corrosion resistance and other superior properties, and is widely applied in aerospace, medical treatment, chemical industry and other fields. Large quantities of scraps are generated during the production and processing of titanium products. Titanium scrap mainly originates from titanium sponge production, ingot processing, finished material manufacturing and discarded titanium products. The scrap rate can reach 40% to 60% in material forming processes. Efficient recycling of titanium scrap reduces resource waste and brings remarkable economic returns, strategic value and environmental benefits.
We introduced the sources and classification of titanium scrap in” Analysis of the Whole Recycling Chain of Titanium Scrap: Source Composition and Classification System”, and elaborated its development history in “Introduction to the Research History of Global Titanium Scrap Recycling and Utilization”. This paper focuses on another core part, namely the mainstream processes and key procedures of titanium scrap recycling.
Titanium scrap recycling technologies are categorized into smelting methods, hydrometallurgical technologies and innovative combined processes. They differ in technical principles, procedural design and applicable scenarios. The details and practical procedures are illustrated below, with key information summarized in tables.
1. Smelting Recycling Method (Pyrometallurgy, Dominant Industrial Technology)
This method melts and purifies titanium scraps under high-temperature vacuum conditions, and is the most commonly adopted technology in industrial production. It consists of five specific processes.
| Process Name | Core Procedures | Key Advantages | Main Limitations | Applicable Scenarios |
| Vacuum Arc Remelting (VAR) | Scrap pretreatment → Electrode preparation → Vacuum smelting → Ingot forming | Low energy consumption, short cycle and low investment; skull melting can directly produce castings | Complicated and costly electrode preparation; incapable of removing high and low density inclusions | Mass recycling of regular-shaped scraps such as plates and cuttings for conventional titanium ingots |
| Non-consumable Electrode Arc Melting (NCEAM) | Rough cleaning → Continuous feeding → Arc melting in argon/helium atmosphere → Degassing and purification → Ingot forming | No electrode preparation required, low cost, high efficiency and good purification effect; high tolerance to oily and oxidized scraps | Only suitable for small-batch production | Production of small-sized titanium ingots with high purity and added value |
| Electron Beam Melting (EBM/EBCHM) | Batching and mixing → Vacuum treatment → Electron beam melting → Refining and purification → Solid ingot formation | Large industrial scale, thorough deoxidation, high adaptability to various scrap shapes and prominent purification performance | Volatile alloy elements like Al and V are prone to burning loss, bringing difficulties to composition control | Manufacturing of high-purity large aerospace titanium slabs, covering over 80% of global recycled aerospace-grade titanium slabs |
| Vacuum Plasma Beam Melting (VPBM/PBM) | Preliminary screening → Crushing → Cleaning and drying → Plasma beam melting → Cold hearth refining → Billet solidification (secondary VAR smelting available) | High vacuum of 10⁻²~10⁻³Pa; 0.02-0.04% oxygen removal rate and 50-70% carbon & nitrogen removal rate; no restriction on scrap shape | High equipment investment | Recycling requiring high yield, thorough impurity removal and uniform composition |
| Skull Furnace Melting | Pretreatment of irregular bulk scraps → Mold placement → Titanium liquid pouring → Electrode assembly or direct forming | Flexible process to handle irregular scraps | Limited application scope | Production of electrode bars and small castings such as pumps and valves |
2. Hydrometallurgical Technology (Supplementary Recycling Route)
The technology operates in aqueous solution below 200°C. Titanium is selectively dissolved by acid, alkali or oxidant, and intermediate products are obtained via multi-step purification before being reused for titanium sponge manufacturing. It performs well in treating high-oxygen and high-impurity scraps, yet most relevant techniques are still under pilot and demonstration stages.
| Process Name | Core Procedures | Key Advantages | Main Limitations | Applicable Scenarios |
| Hydrochloric Acid Leaching-Solvent Extraction | Crushing and degreasing → Leaching in 15%-20% hydrochloric acid at 80-100°C → Filtration → TBP extraction → Back extraction → Hydrolysis and calcination → Titanium dioxide production | Titanium leaching rate above 95% and high efficiency, adaptable to various scrap forms | Large acid consumption and mandatory tail gas recovery system | Recycling of machining scraps and anode fragments for titanium dioxide production |
| Sulfuric Acid Leaching | Crushing and degreasing → Reaction with 93%-98% concentrated sulfuric acid at 200-250°C → Dilution and filtration → pH adjustment (2.5-3.5) precipitation → Calcination → Titanium dioxide production | Low raw material cost, suitable for high-oxygen and high-impurity scraps | Long 8-12 hour leaching cycle; 85%-90% titanium recovery rate, lower than hydrochloric acid method | Disposal of hard-to-recycle scraps including discarded chemical equipment parts |
| Molten Salt Electrolysis (Combined Pyro-hydrometallurgy) | Crushing → Mixing with NaCl-KCl molten salt at 700-800°C → DC electrolysis → Cathodic reduction → Titanium powder purification | Direct production of metallic titanium with purity over 99.5% | High energy consumption and production cost | Recycling of high-value scraps such as Ti-6Al-4V medical implants |
| Hydrogenation-Dehydrogenation (HDH) | Scrap feeding → Hydrogenation at 350-450°C → Argon-protected ball milling → Vacuum dehydrogenation at 550-650°C for 4-5 hours → Titanium powder preparation | Effective treatment of loose scraps, excellent inclusion removal capacity and high product purity | Special hydrogenation and dehydrogenation equipment required | High-Purity Titanium powder for additive manufacturing, medical implants and coatings |
3. Innovative Combined Processes (Future Development Trend)
From 2023 to 2025, a host of innovative technologies have advanced from laboratory research to pilot and industrial demonstration. Multi-technology integration breaks the limitations of traditional techniques, falling into four categories: new pyrometallurgical routes including vacuum plasma-electron beam dual furnace melting and hydrogen-assisted electron beam melting; new hydrometallurgical routes such as supercritical water oxidation-hydrochloric acid combined treatment and deep eutectic solvent dissolution-electrodeposition; direct powder preparation technologies covering supercritical hydrogen HDH treatment and inductive plasma spheroidization; closed-loop additive manufacturing represented by scrap-HDH-LPBF printing-waste recycling cycle. These processes balance purification performance and resource utilization rate, creating new solutions for high-end titanium scrap recycling.
Conclusion
Process selection depends on scrap morphology, impurity content, target purity and economic cost. Mature and reliable smelting methods dominate industrial production and fit large-scale conventional scrap recycling. Hydrometallurgy provides viable solutions for special high-oxygen and high-impurity scraps with lower energy consumption but lengthy procedures. Innovative combined processes meet high-end demands and drive the development of efficient, eco-friendly and closed-loop recycling.
Continuous technological upgrades will advance purity control, cost reduction and process simplification, fully unlock the economic and strategic value of titanium resources and boost sustainable development of the titanium industry. In the future, multi-process integration, intelligent control and full-chain closed-loop operation will become core development trends, offering solid support for global circular resource utilization.