The Elkington specimen of cathode copper

ABSTRACT

The specimen of cathode copper dated 1880 in the Percy Collection of the Science Museum, London was produced in the world’s first copper electrorefinery located at Pembrey in South Wales, based upon the only known application of jar-cell technology patented by James Elkington in 1869. Drill samples were taken and assayed by ICP-MS for a total of 23 impurity elements, of which 12 were considered for the study. Their average aggregate value of about 20 ppm compares very favourably with about 23 ppm for the same impurities in typical modern cathode. The average silver assay, 2.9 ppm Ag, is very low by modern standards, indicating an anode low in silver, possibly associated with low levels of Pb and Sb and relatively high levels of As and Bi. This unusual combination of anode impurities coupled with exceptional cathode purity is discussed in relation to the contemporary conditions in the Welsh copper industry.

KEYWORDS:

• Copper
• electrorefining
• sampling
• cathode quality
• historical

Acknowledgements

The authors are indebted to the Science Museum, London for access to the Percy collection and warmly acknowledge the help of Rebecca Storr, Collections Access Coordinator, in bringing this project to fruition. It is also a particular pleasure to acknowledge the generous offer of assay services provided by Glencore - CCR, East Montreal, Quebec.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Blake’s catalogue identifies the cathode specimen as ‘Electro-deposited copper from the Pembrey Copper Works, Birmingham’. The stated location is an understandable misapprehension. The Pembrey Copper Works was located beside Burry Port harbour in South Wales; it was an offshoot of Elkington, Mason & Co., a leading large scale manufacturer of electroplate and electrotype objects with extensive works in Birmingham.

2 The selected material was Polyfoam ECO Floorboard Super, compression strength 500 kPa at 10% deformation, generously supplied by Knauf Insulation Ltd., Sheffield, UK.

3 Craddock and Hook (2012) report assay results for a cathode recovered from the wreck of the SS Benamain which was probably made in South Wales in 1893. However, the high detection limits of their chosen analytical method (ICP-AES) render the results unhelpful for comparison here.