Fast, automated inbound material identification (IMI) and inspection for metal scrap yards

Description of need

Scrap yards need fast, automated solutions for inbound material identification (IMI).

How do you know what is actually representative of what you are receiving when you cannot see what is in the middle or the bottom of the pile?

Requirements:

They need to group the metal scrap into Al+Mg alloys, ferrous steel, cast iron, stainless steel, Zn alloys, brasses, and bronzes.
Must be fast (entire truckload in a couple of minutes)
Must determinate the amount of contamination (dirt, moisture, oils, concrete, paper wood, plastic, radioactive materials…)
Must distinguish between alloys and their alloys

Metal scrap yards

Positive material identification (PMI) is a $5B industry. XRF is the predominant technique, especially handheld XRF devices.

Note: many of these more recent technologies are also relevant to cargo inspections and other spectroscopy applications (see examples).

Manual inspection with a knife and a magnet
Dual energy X-ray transmission. Current commercial sensors do not have sufficient resolution to distinguish between the dense metals or their alloys, or between the light metals and their alloys.
X-ray fluorescence (WRF). Suffers from relatively low precision for and difficulty in detecting light elements. Has variable penetration depth.
Laser induced breakdown spectroscopy (LIBS). Sensitive to surface contamination and microstructural inhomogeneity. Struggles with Pb alloys and refractory metals.
Prompt gamma neutron activation analysis (PGNAA). Widespread in mining industry. Newly developed D-T fusion neutron sources are now beginning to be deployed in PGNAA sensors for cross-belt analyzers. PGNAA cross belt analyzers, which do not have sufficient resolution to target individual scrap pieces.
Mechanical sweeps (pneumatic or magnetic)
Magnetic separations (including rare-earth based, but never HTS based)

Unknown beyond the technologies listed above