Conflict Minerals and the Congo: Where the World's Tantalum Is Processed

The U.S. Geological Survey traces mineral supply chains — from ore, through intermediate forms, to finished products — to spot risks to U.S. supplies of critical minerals and to make those chains more transparent for policymakers. Government and non-governmental groups asked its National Minerals Information Center about plants worldwide that process tantalum, tin, tungsten and gold (the "3TG" minerals), in response to U.S. law aimed at cutting the links between the trade in these minerals and armed conflict in the Democratic Republic of the Congo and neighbouring countries.

Company and industry representatives identified the smelters and refineries that turn 3TG ores and concentrates into metal as the point in the chain where minerals can be traced back to their mine of origin — essential to a transparent, conflict-free supply. This is the second USGS fact sheet in the series, after one on tungsten in August 2014, and it lists selected companies that processed tantalum commercially in 2013–14. It says nothing about where those plants got their material.

From ore to metal

Tantalum ore is very low grade — only 0.02 to 0.04 percent tantalum oxide (Ta₂O₅) — made up of various tantalum minerals mixed with others. It is first beneficiated, concentrated physically without chemical change, into a concentrate of 20 to 40 percent Ta₂O₅ equivalent, typically about 30 percent. The concentrate is then dissolved in acid at high temperature and reacted to yield K-salt (potassium fluorotantalate, K₂TaF₇) or tantalum oxide. Further processing makes tantalum metal powder and other products, and the metal is worked into a range of mill products.

Two other feeds complicate the chain: synthetic concentrate, a form in which tantalum is recycled from industrial processing, and tantalum-bearing tin slag, both of which can enter alongside concentrate from ore.

Uses

Tantalum can store and release energy, so electronics takes more than half of world mine production. Tantalum components can be extremely small, and no other element can replace it without degrading performance — hence its place in mobile phones, hard drives and hearing aids. Being highly biocompatible, it coats cheaper, stronger materials such as stainless steel in medical devices: blood-vessel stents, bone replacements, plates, suture clips and wire. It resists corrosion, so it lines chemical-industry pipes, tanks and vessels; tantalum carbide's hardness suits cutting tools; and tantalum oxide raises the refractive index of lens glass.

The processors

More than 30 tantalum processors were part of the global supply chain in 2013–14, in Austria, Brazil, China, Estonia, Germany, India, Japan, Mexico, Russia and the United States. Their products included K-salt, tantalum oxide, carbide, chloride, powder, metal, alloys and ferroniobium-tantalum. Plants known to process only recycled material were left out. Those offering K-salt or tantalum oxide — the first products made from concentrate — or reporting that they use concentrate are potential consumers of mined concentrate.

The USGS stresses the limits. It cannot verify whether any of these plants used tantalum concentrate or, if they did, whether it came from conflict-affected areas; synthetic concentrate, tin slag or intermediate products may be their feed. The chain is complex and often opaque: companies run plants in several places and countries, report what they sell rather than which plant uses which materials, change names and owners, or go out of business. The information came from company reports, foreign governments, industry analysts and associations, intergovernmental and non-governmental organisations and trade journals, with company names, locations and products checked against company websites. The aim was to list every concentrate-consuming plant, but some may be missing, and many companies reported as suppliers could not be confirmed.

Sources

• Papp, J.F., 2014, Conflict minerals from the Democratic Republic of the Congo — Global tantalum processing plants, a critical part of the tantalum supply chain: U.S. Geological Survey Fact Sheet 2014–3122. https://pubs.usgs.gov/publication/fs20143122
• The sheet's full table of plants, with their locations, operators and products, is in its PDF.
• Map: U.S. Geological Survey.
• Rewritten in hubnx's own words.