The Contemporary Anthropogenic Chromium Cycle

Abstract

Chromium is an essential engineering metal used in stainless and alloy steels, chemicals, and refractory products. Using material flow analysis, all major anthropogenic chromium flows are characterized for the year 2000, from mining through discard, on three spatial levels: fifty-four countries, nine world regions, and the planet. Included is the first detailed quantification of chromium in internationally traded finished products and diverse waste streams. Findings include (1) 78% of chromium flow entering final use is added as a net addition to stock on the global level; most countries are close to this figure; (2) the majority of mining occurs in Africa (2400 Gg Cr/yr) and the Commonwealth of Independent States (1090 Gg Cr/yr), while the major end-users are Asia, Europe, and North America at 1150, 1140, and 751 Gg Cr/yr, respectively; (3) waste flows of chromium are the greatest in Europe (420 Gg Cr/yr), Asia (370 Gg Cr/yr), and North America (290 Gg Cr/yr), but the composition of these waste flows varies greatly among the world regions; (4) releases of chromium by the global system, which total 2630 Gg Cr/yr, are nearly evenly divided among tailings, ferrochromium slag, downgraded scrap, and post-consumer losses; (5) many countries have a heavy foreign dependence on chromium in the all forms, as is demonstrated for the United States. The findings relating to in-use stock changes and finished product trade are relevant to industry, allowing for more accurate planning for future scrap availability. The quantification of releases due to discards and dissipation hold environmental and human health relevance, while the full life cycle international trade assessment addresses local scarcity.

Global Substance Flow Analysis of Indium

“…It is likely that the lost indium is in the mining tailings and the sludge from smelters. The yield rates for other metals were estimated as follows: 86% for copper, 26) 73% for silver, 27) 73% for chromium, 28) 82% for zinc 7) and 87% for nickel. 29) These figures demonstrate that the yield rate for indium is significantly lower than those for other metals, which may be attributed to the difficulty of extracting indium compared with other metals.…”

Substance Flow and Stock of Chromium Associated with Cyclic Use of Steel in Japan

“…The material flow of carbon steels and alloy steels other than stainless steel, however, has not been investigated from the perspective of Cr flow. Johnson et al 6) conducted a static substance flow analysis of Cr on a global scale for the year 2000. They estimated the Cr content in waste scrap recovered from end-of-life products by multiplying the amount of waste stream (including scrap) by the percentage of Cr content, which was assumed to be the same throughout the world.…”

Does the EU migration level of chromium VI in toys need to be lowered?

“…Chromium VI occurs in rare minerals and may be naturally occurring in groundwater (McNeill et al, 2012), however, chromium VI in the environment is almost totally derived from human activities (WHO, 1990;Kimbrough et al, 1999;Johnson et al, 2006 Major sources of chromium emissions to the air are the production of chromium VI compounds and metal treatment (6.2 t/y and 12 t/y, respectively). Important sources of chromium releases to water are metal treatment use (estimated at 2,342 t/y), chrome tanning salt production (38 t/y), chromium trioxide production (22t/y) and metal treatment formulations (12 t/y), while wood preservative application is the main source for chromium in soil (6.2 t/y) (all data valid for the EU; ECB, 2005).…”