Copper cathode grades: what "Grade A" and 99.99% really mean

"Grade A, 99.99%" appears on almost every cathode offer. It is worth knowing what it means, and when a number on an offer is impossible.

Grade A cathode

On the London Metal Exchange, Grade A copper cathode must meet a recognised standard: BS EN 1978:1998 (Cu-CATH-1) or ASTM B115 cathode grade 1. These set limits on impurities such as silver, sulphur, iron, lead, bismuth, selenium and tellurium, not just a headline copper percentage.

"99.99%" is shorthand. What matters to a buyer's plant is the impurity profile, so ask for the full assay.

LME brands

Only cathode from producers whose brand is registered with the LME can be delivered against LME contracts. Many African producers make good cathode that is not LME registered. That isn't fraud, but it affects price, and some buyers' plants or contracts require registered brands. Check that the brand claimed matches the producer and the country of origin.

Other copper products

• Blister copper: about 98–99% copper, an intermediate product for refining.
• Anode: cast copper for electrorefining into cathode.
• Concentrate: typically about 20–40% copper, sold with payable terms and treatment and refining charges.
• Ore: run-of-mine or crushed rock, often a few per cent copper.
• Scrap: graded by its own standards. See copper scrap grades.

Claims that are impossible

• 99.99% copper concentrate. Concentrate cannot be 99.99% copper. That is a cathode number pasted onto the wrong product.
• Ore at 40% or more described as run-of-mine, with no explanation. High-grade ore exists, but it needs proof.
• A perfect assay on every page, identical across lots and dates.

Our document check flags copper contents that don't fit the product.

In the contract

Write the standard (for example BS EN 1978 Cu-CATH-1), the brand if it matters, the inspection company, the sampling method and the laboratory, and what happens if the material fails.