Global mining companies have responded to a call by ethical investors working on a global standard for tailings dams to provide information about the facilities that they control, with several companies having published information about their tailings storage facilities (TSFs).
These include major diversified majors BHP Billiton, Anglo American and Glencore, as well as gold miner Gold Fields. Several other mining companies, such as Russia-focused Polymetal and Brazil-focused Serabi Gold last month already disclosed their TSF management plans.
In its presentation, BHP announced the creation of a dedicated tailings task force to drive an enhanced focus on internal dam management and to support the development of international best practice. It was also investigating new technologies to further mitigate current dam risks and eliminate future risk.
BHP’s review identified no immediate concern about the integrity of any of its 67 operated dams, only 13 of which are currently active. Twenty-nine of the company’s operated facilities are upstream dams, of which five are active.
The miner reported that 32 of its TSFs fell in the “high”, “very high” or “extreme” classification for hypothetical loss of life and damage to surround areas if a failure were to occur without any controls. The classification from the Canadian Dam Association did not measure the stability of the dams or the likelihood of them bursting.
Five of the active dams carry an “extreme” consequence classification, three of which are in Australia, one in the US and one in Peru.
Dam safety at BHP has been in the spotlight following the deadly 2015 dam failure at its Samarco joint venture (JV) with iron-ore giant Vale that caused Brazil’s worst environmental disaster. BHP is now facing a $5-billion class action damages claim in England for alleged negligence in relation to that disaster.
In January this year, dam safety was again brought to the fore when Vale’s Brumadinho dam burst, killing more than 300 people. Following the tragedy, a group of 96 institutional investors (representing more than $10.3-trillion assets under management) wrote to 683 extractive companies seeking greater disclosure on the management of TSFs.
The Church of England Pensions Board had argued that mining companies’ disclosure about TSFs were “largely inadequate”.
In its release on Friday, Glencore said investors and communities had “quite rightly” called on extractive companies to increase their disclosure on TSFs following the Brumadinho disaster.
Glencore has launched a microsite where information about its TSFs could be accessed.
CEO Ivan Glasenberg commented that the safety of its workforce and the communities living around its assets was a priority for the group. Glencore said TSFs had been part of the group’s catastrophic hazard evaluation programme for a “number of years”.
Fellow diversified miner Anglo American confirmed the integrity of the 91 TSFs that it manages, as well as the 62 dams at nonmanaged JV operations. The company’s dams are kept to global safety standards, using advanced technologies such as satellite monitoring, fibre optics and microseismic sensors.
CEO Mark Cutifani stated that the group was working on a number of technologies that should significantly reduce the volume of waste material produced, as well as increase the operations' ability to have water removed from material and store it in drier form – improving stability and reducing associated risks.
“A number of these technologies also offer major energy and fresh water use reductions for every ounce or tonne of metal or mineral produced.”
Anglo revised and updated its technical standard for TSF safety management early in 2014. This mandatory global standard mitigates the risk that TSFs pose and sets minimum requirements for design criteria, monitoring, inspection and surveillance.
Of the 91 TSFs managed by Anglo, 40 are active, 33 are inactive or in care and maintenance, and 18 are closed or being rehabilitated. In terms of tailings storage method, 39 of the TSFs use wet deposition while 52 use either dry-stacked or in-pit deposition.
South Africa-headquartered Gold Fields, whose operations are outside the country – except for the South Deep mine – said it managed 32 tailings facilities, of which 12 were active and one would be commissioned imminently. A further two were operated by JVs.
The company stated that its TSFs were subject to an external audit at least every three years. Additional safety inspections had also been done following the Brumadinho disaster.
Gold Fields said that to improve the operational safety of its TSFs, Gold Fields was considering moving away from the construction of upstream facilities to centre-line or downstream design. It was also considering filtered and dry stacked tailings, as well as in-pit tailings disposal.
There is currently no consolidated global public register of TSFs. It has been estimated that there are about 18 000 TSFs worldwide, of which around 3 500 are active. It was owing to the absence of such a register that the investor initiative called for action.
Platinum miner Lonmin, which has operations in South Africa and was recently bought out by precious metals miner Sibanye-Stillwater, noted in questionnaires published on its website, that all its tailings dams were built using the upstream method.
It has 12 such facilities, of which seven are active.
It added that, following the Brumadinho’s incident, SRK Consultants had reviewed its tailings dams to ascertain the operating regime and stability. "All dams were confirmed to be operated within the design parameters and the risk to be within acceptable limits."