Deep-Sea Tailings Disposal

Terrestrial mining activity produces large volumes of waste, formed by the non-processed rock from overburden or access tunnels and shafts, and by the processed tailings. The tailings are the waste produced after the extraction of the targeted metal from the ore through crushing and milling to obtain particles that consist of one mineral and separating the minerals by their physical or surface characteristics. This fine-fraction slurry waste usually accounts for a high proportion of the ore.

Traditionally, tailings have been stored in land dams, but the lack of land availability, potential risk of dam failure, geological instability and topography in coastal areas in certain countries results in increasing disposal of tailings into marine systems. However, there are many important gaps in the understanding of the environmental impacts (including abiotic and biological processes) of such disposals and recovery potential of affected areas, particularly in poorly known deep-sea ecosystems.

The DOSI DSTD working group aims to provide an international platform to promote discussion and communication amongst stakeholders to provide guidance on issues related to deep-sea mine tailings disposal (DSTD). The WG (currently 75 members) includes natural sciences researchers, industry, environmental groups, consultants and policy makers.

Current Working Group  Activities:

  1. Identify new lead or co-lead for working group
  2. Progress forward with participation in the newly formed GESAMP (Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection) Working Group on the impacts of wastes and other matter in the marine environment from mining operations, including deep-sea mining (WG 42,, led by Dr Tracy Shimmield.

Recent Working Group Activities:

1) DSTP workshop, Lima (Peru), June 2015: workshop organised in collaboration with GESAMP/IMO. Co-funded by IMO and the MITE-DEEP project (INDEEP & NFR). DOSI-DSTP funded the participation of 10 scientists which presented up to date data and knowledge on DSTP issues, from ecology, chemistry and physical oceanography to modelling.  Meeting report with contributions from DOSI.

2) A Scoping Paper designed as a tool that will help all stakeholders to better understand deep-sea tailings disposal has been submitted (Sept 2017)

Want to get involved?

If you are interested in participating in the DOSI-DSTP working group, please contact WG Lead Eva Ramirez-Llodra:

DSTP Meeting Peru June 2015
DSTP Meeting Peru June 2015