The JSE-listed subsidiaries of global miner Anglo American have confirmed the structural integrity of their tailings dams, in line with a global call for better disclosure concerning tailings storage facilities (TSFs).

Anglo American Platinum (Amplats) operates nine mineral residue facilities, of which six are managed TSFs and three are slag stockpiles. The company has eight TSFs at nonmanaged joint venture (JV) operations.

“As part of global efforts to improve the transparency around TSFs, we are providing detailed information on each of our facilities in response to a request from a number of global institutional investors. We have confidence in the integrity of Amplats’ managed TSFs, which are subject to the highest global safety and stewardship standards,” said Amplats CEO Chris Griffith.

He further explained that all Amplats’ managed tailings dams were built using the upstream method, except the Blinkwater dam at the Mogalakwena mine, in the Limpopo province, which used a downstream method of construction, and Dam 1 at the Unki mine, which used a hybrid downstream and upstream method.

Upstream tailings dams are generally considered to be an appropriate design for facilities in dry and seismically stable regions with flat topography, such as the locations of Amplats’ TSFs in South Africa and Zimbabwe.

Anglo subsidiary Kumba Iron Ore CE Themba Mkwanazi also confirmed the integrity of the four TSFs Kumba manages.

The four TSFs are located at the company’s two operating mines in the Northern Cape. Of the four TSFs, one is an active facility, constructed as a water retaining structure, at the Kolomela mine, while the other three are located at the Sishen mine and were built using the upstream method of construction. Only one of the three is active.

Mkwanazi also stated that upstream tailings dams were generally considered to be an appropriate design for the locations where Kumba operates.

Anglo’s Group Technical Standard, which applies to all TSFs managed by Kumba and Amplats, sets minimum requirements for design criteria, monitoring, inspection and surveillance, and has been peer-reviewed by international specialists.

In line with that standard, all TSFs managed by Kumba have a competent person in charge and an externally appointed engineer of record, providing continuous technical management from initial design and construction to monitoring and support. A dedicated team of engineering specialists at Anglo provides strategic direction and technical assurance.

“As an industry, there is a clear ethical and moral imperative to do everything possible to ensure that TSFs are managed to the highest standards of safety, using appropriate advanced technologies, and to work together to build greater levels of trust with all stakeholders,” said Mkwanazi.

Anglo American published details of all 91 of its managed TSFs and an additional 62 TSFs at nonmanaged JV operations.

CE MarkCutifani stated that the company was confident of the integrity of its managed TSFs, which are kept to global safety standards using advanced technologies such as satellite monitoring, fibre optics and microseismic sensors.

He added that the company was working on a number of technologies that should significantly reduce the volume of waste material produced, as well as increase the operation’s ability to remove water from material and store it in drier form, improving stability and reducing associated risks.

“A number of these technologies also offer major energy and freshwater 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 the tailings storage method, 39 of the TSFs use wet deposition, while 52 use either dry-stacked or in-pit deposition.

Anglo and its subsidiaries joined several companies in disclosing information about their tailings dams after a call from investors to the extractive industry to disclose information about TSFs, following the catastrophic tailings dam failure at the Brumadinho dam, in Brazil, which led to the loss of more than 300 lives.

In April, a group of 96 institutional investors (representing more than $10.3-trillion in assets under management) asked 683 extractive companies to ensure greater disclosure concerning the management of TSFs.

The Church of England Pensions Board had argued that mining companies’ disclosure about TSFs were “largely inadequate”.

There is currently no consolidated global public register of TSFs. It has been estimated that there are about 18 000 TSFs worldwide, of which about 3 500 are currently active. It was due to the absence of such a register that the investor initiative called for action.

Glencore
LSE- and JSE-listed Glencore said this month investors and communities had “quite rightly” called on extractive companies to increase their disclosure on TSFs.

Glencore has launched a microsite where information about its TSFs can be accessed.

CEO Ivan Glasenberg said the safety of Glencore’s workforce and the communities living around its assets was a priority for the group. Glencore said that TSFs had been part of the group’s catastrophic hazard evaluation programme for a “number of years”.

Gold Fields
South Africa-headquartered Gold Fields, whose operations are outside the country – except for the South Deep mine – said that 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 it was considering moving away from the construction of upstream facilities to centre-line or downstream design to improve the operational safety of its TSFs. It was also considering filtered and dry-stacked tailings, as well as in-pit tailings disposal.

Lonmin
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 incident, SRK Consultants had reviewed its tailings dams to ascertain the operating regime and stability. “All dams were confirmed to be operating within the design parameters and the risk [was confirmed] to be within acceptable limits.”

Bhp Group
In its presentation, BHP announced the creation of a dedicated tailings task force to drive 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 at any of its 67 operated dams, of which only 13 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 in terms of hypothetical loss of life and damage to surrounding 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 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 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.