Tin pest contamination in the US National Defence Stockpile (NDS) stockpile is being remediated over time using a simple remelting process to upgrade the more than 4,000 tonnes stored back to a 99% pure tin grade.
The stockpile, currently administered by the Defence Logistics Agency (DLA), was made in response to the Strategic and Critical Materials Stockpiling Act of 1939 to provide a reserve of strategic materials and minerals considered vital for military, industrial and civilian needs in times of national emergency. In the years leading up to World War II tin was considered a critical material for the US and supply was highly dependent on production from what is now Malaysia, Indonesia, Thailand and Myanmar. Indeed supply was cut off shortly after the war started. Up to 200,000 tonnes may have been stored at various locations.
It has been known for some decades that ingots in the stockpile had issues with tin pest, causing crumbling and dust formation, probably as a result of long-term air pollution and cold outdoor temperature storage conditions. The remediation work will halt further degradation and restore marketable value to the tin.
The work is being carried out by the Rock Island Arsenal Joint Manufacturing and Technology Center, Rock Island, Illinois and is expected to take 5-7 years to complete.
