Mercury is a ubiquitous element that occurs naturally and is emitted through various anthropogenic sources. It is introduced into the cement production process, occurring in both raw materials and fuels. Concentrations may vary in a wide range from one raw material or fuel to another, from deposit to deposit or even within one quarry.
Due to its high toxicity for human health and the environment, mercury emissions are being addressed on a global level by the Minamata Convention on Mercury – a global and legally binding treaty targeting the reduction of mercury emissions. The import, export and production of products containing mercury, such as batteries, switches, some medical devices and cosmetics will be banned by 2020. Plans to reduce and eliminate mercury emissions from artisanal and small-scale gold mining will be established, promoting mercury-free alternatives. Plans to minimise mercury emissions from existing industrial mercury emitters such as coal-fired power plants, cement plants or waste incinerating plants are to be drawn up, while new facilities are to install Best Available Techniques (BAT).
Mercury emission limits
Emissions of mercury are regulated in many countries. Where emission limit values are in place, they range (with few exceptions) between 0.03 – 0.1 mg/m3 as a daily average. In the EU, industrial mercury emissions are covered by the Industrial Emissions Directive (IED), which has been transposed into most Member States’ legislations in the last two years. They are limited to 0.05 mg/m3 for furnaces co-incinerating waste fuels, sampled over a period of 30 minutes to 8 hours.
In the United States, new mercury emission limit values will come into effect from September 2015 on. Emissions for existing kilns will then be limited on a by-product basis to 27.5 kg per million (metric) t of clinker produced. For new kilns, the limit is more stringent with 11.5 kg per million t of clinker produced. These emission limits, based on a 30-day rolling average, are so low that the local cement industry is being required to examine new methods of mercury control.
Read the article online at: https://www.worldcement.com/europe-cis/13042015/challenging-mercury-emission-limits-and-measures-671/