Copper cathode Grade A (LME, BS EN 1978): certificate of analysis, brands and tolerances

Copper cathode Grade A is the reference product of the world copper market. It is the only shape and quality deliverable against the London Metal Exchange copper contract, and almost every physical cathode contract, whether for a cable maker in Germany or a rod mill in Vietnam, is written by reference to it. This article explains what Grade A means, what a certificate of analysis must show, and the tolerances a buyer should expect in a genuine contract.

What copper cathode Grade A means

Under the LME copper contract, Grade A cathode must conform to BS EN 1978, grade Cu-CATH-1, and must be of a brand registered with the exchange. The standard specifies electrolytically refined cathode with a copper content of 99.99 % minimum and individual and grouped limits for the impurities that matter for electrical conductivity and downstream processing. The limits most often tested and most often failed are:

• Bismuth: maximum 2.0 ppm; selenium and tellurium each maximum 2.0 ppm, with the sum of selenium, tellurium and bismuth not exceeding 3.0 ppm
• Lead: maximum 5 ppm
• Sulphur: maximum 15 ppm
• Silver: maximum 25 ppm
• Total of all specified impurities: maximum 65 ppm

Antimony, arsenic, iron, nickel, tin, zinc and the other listed elements carry their own individual and group limits. Physical requirements also apply: cathodes must be free of excessive nodulation, flaking and adhering electrolyte, because surface contamination reports as impurity when the cathode is melted.

Why the brand matters more than the assay

The LME approves brands, not certificates. A producer applies to register a brand, submits assays from independent laboratories and consumer references, and the brand is then listed with its producer, country and cathode dimensions. Cathode of a registered brand is accepted by warehouses, rod mills and banks on the strength of the brand marking and the producer's certificate, because the producer's reputation and listing are at stake with every bundle. A certificate stating "Grade A, 99.99 %" for an unbranded or unlisted product carries none of that weight, even if the numbers on it are correct.

Rule: Grade A is a registered brand conforming to BS EN 1978 Cu-CATH-1 in a verifiable warehouse. A certificate without a brand, a brand not on the LME list, or a warehouse that cannot be reached independently means the product is not Grade A, whatever the document says.

What a genuine certificate of analysis contains

A producer's certificate of analysis for a cathode shipment states the brand, the lot or cast numbers, the number of bundles, the gross and net weights by bundle, the chemical analysis of each lot against the Cu-CATH-1 limits with the method used, and the standard it conforms to. Trace elements are determined by methods such as inductively coupled plasma or glow-discharge mass spectrometry, and copper content is usually stated by difference. A certificate that gives a single analysis for a 5,000 t shipment, lists no bundle numbers or quotes impurities to one decimal place in percent has not come from a refinery. An independent inspection certificate from SGS, Intertek, Alex Stewart or Bureau Veritas, issued on samples drilled from randomly selected cathodes under the inspector's control, is the buyer's check on the producer's figures.

Weights, bundles and documents

Cathodes are supplied in strapped bundles of roughly one to two and a half tonnes depending on the producer, with each bundle tagged with brand, lot and weight. The commercial invoice is based on net weights determined on calibrated scales at the point of delivery, with an inspection weighing report where the contract requires one. Documents under a letter of credit governed by UCP 600 typically include the commercial invoice, bill of lading, packing list with bundle numbers and weights, producer's certificate of analysis, inspection certificate of weight and quality, and a certificate of origin. For LME-warranted metal, title passes by transfer of warrants through the exchange's depository system, and no physical document from the seller is required to prove existence.

Tolerances in a real cathode contract

Red flags in cathode offers

1. Price quoted as a discount to LME instead of a premium over LME cash.
2. Large tonnages in a warehouse that is not an LME-listed facility and cannot be visited by the buyer's inspector without the seller's escort.
3. A brand that is not on the LME approved list, or a certificate that names no brand.
4. A demand for a bank instrument, a comfort letter or a deposit before inspection.
5. Certificates whose impurity figures are copied from the standard's limits rather than measured.

A refinery or a trader with cathode in a listed warehouse will welcome an inspector, provide bundle lists, and price at a premium. Anything else is a reason to stop.