Purification and treatment of titanium and titanium alloy scrap

       Titanium and titanium alloys, with their exceptional properties, have found extensive applications in various fields, including aerospace, medical technology, and chemical engineering. During the production and processing of titanium and titanium alloys, multiple types of scrap inevitably arise, primarily categorized into two forms: chip-like and lump-like. If these residues are not properly treated and recycled, they not only waste resources but may also adversely impact the environment. Therefore, effectively purifying titanium and titanium alloy residues to enable their recycling holds significant practical importance.

Types of Residue Contamination
Both chip-like and lump-like residues undergo varying degrees of contamination during their formation.

The primary contamination types include:
1. Oil and Coolant Contamination: During titanium and titanium alloy processing, oils and coolants are commonly used to reduce processing temperatures and minimize tool wear. These substances readily adhere to scrap surfaces, causing contamination.
2. Ferromagnetic Material Contamination: Ferromagnetic materials present in processing equipment or tools may transfer to scrap during operations, resulting in contamination.
3. Non-ferromagnetic contamination: Beyond ferromagnetic materials, other non-magnetic impurities may also contaminate scrap, compromising its purity.
4. Oxygen and nitrogen contamination: During processing, localized heating of scrap can cause reactions with atmospheric oxygen and nitrogen, forming oxides and nitrides that degrade scrap properties.

Purification Process for Chip-Form Residue
The purification of chip-form residue requires multiple steps to ensure its quality meets recycling standards.

The specific process is as follows:
1. Crushing: First, the chip-form residue is crushed to achieve more uniform particle sizes, facilitating subsequent cleaning and screening operations.
2. Cleaning: Appropriate cleaning methods are employed to remove surface contaminants such as oils and coolant residues from the scrap. Common techniques include solvent cleaning and alkaline washing, with the choice of cleaning agent and process determined by the scrap's contamination level and properties.
3. Drying and Screening: Cleaned titanium scrap is dried to eliminate moisture, preventing rust during storage and subsequent use. The dried chips are then screened to ensure particle size compliance with specifications required for various recycling processes.
4. Removal of High-Density Metal Inclusions: Titanium chips may contain high-density metal inclusions that compromise the performance of recycled Titanium Materials. Appropriate methods, such as magnetic separation or gravity separation, must be employed to remove these inclusions.
5. Uniform distribution by spreader: A spreader evenly distributes the processed titanium chips to ensure thorough mixing during subsequent smelting or other treatments, enhancing recycling quality. 6. Inspection: The treated chips undergo inspection to verify compliance with recycling standards for chemical composition, impurity content, and particle size. Only scrap passing inspection may proceed to the recycling stage.

Purification Process for Lump Scrap

Compared to scrap chips, the purification process for lump scrap is relatively simpler, primarily comprising the following steps:
1. Composition Identification: Employ instruments such as eddy current conductivity analyzers, steel inspection mirrors, and portable direct-reading spectrometers to identify the composition of lump scrap. These instruments enable rapid and precise determination of chemical composition, providing a basis for subsequent processing.
2. Scrap Processing: Depending on the scrap's size and shape, shearing equipment like shears or crocodile shears, or flame cutting methods are employed to process the scrap into dimensions meeting recycling requirements. During processing, operational safety must be prioritized to avoid excessive heat generation and sparks.
3. Surface Contamination Removal: Contaminants like scale or oil may coat the scrap surface. Mechanical grinding or chemical cleaning is required to remove these layers and restore surface quality.
4. Inspection: Processed scrap undergoes inspection to verify compliance with recycling standards for composition and surface quality. Approved scrap proceeds to recycling.

       The purification of titanium and titanium alloy scrap is a critical step in achieving resource recycling. By applying appropriate purification processes to both chip-like and lump-like scrap, contaminants can be effectively removed, enhancing the purity and quality of the scrap. This enables its reuse in titanium and titanium alloy production, thereby reducing production costs, minimizing resource waste, and promoting sustainable development.