A tailings closure standard is urgently needed for the tailings industry to outline criteria that will ensure a closure certificate.

This according to Agreenco CEO Fanus van Wyk, a specialist mine rehabilitation services contractor, who discussed the topic during a recent Southern African Institute of Mining and Metallurgy webinar.

"Imagine, what would our tailings facilities look like in 100 years from now?" he asked.

In the absence of any closure standard, existing closure planning, design, costing and implementation will remain a challenge with mining companies hesitant to implement final rehabilitation measures without any guarantee of walk-away closure.

"Tailings facilities cannot be maintained into perpetuity as many mining companies have committed to.

Once these facilities have been closed, they should not be touched again. With closure interventions, one risks opening up a host of environmental problems if the facility is reopened,” he argued.

Van Wyk said closed tailings facilities remained above-ground orebodies, which was part of the problem because there would always be those who would want to reopen them to remine them.

“These are hydraulically deposited civil structures, which cannot be compromised by any means. We have to be realistic about the land’s use. I’m very much for a ‘hands-off’ approach to tailings land use.

“It offers space but, other than space, it is not something to be used by cattle or game or anything else,” he said, noting that any use could compromise the structure and cause not only environmental damage but also potentially endanger human lives.

Tailings facilities have become a permanent feature of landscapes around South African mines and are integrated in urban areas and townships.

There are about 400 metalliferous facilities and more than 150 coal and ash dumps ranging from less than 10 ha to more than 800 ha in size.

Van Wyk said global demand for metals and coal would further drive the need for more tailings deposition facilities and that it was critical for these facilities to built and managed more sustainably.

Regulatory regimes, long-term lifecycle decision-making frameworks and cost models for these facilities have, in the past, brought about industry culture, construction methodologies and operational procedures that may continue to create legacy impacts, he noted.

Tailings facilities pose significant environmental challenges, ranging from spills to erosion, water seepage, dust pollution, contingent maintenance costs and uncertainty about final rehabilitation requirements. These issues are becoming more pressing, considering long-term human and environmental health, Van Wyk said.

The webinar discussion, led by Van Wyk, sought to challenge the conventional tailings design paradigm for the long-term perspective and provide practical lessons from 70 years of rehabilitation projects.

He expressed the hope that these lessons would be considered for future tailings design.

The main design challenges, he said, related to design information around initial ore geochemistry, geotechnical considerations, geometry, footprint decisions, standardised net present value cost models informing project viability and assumptions about the effectiveness of final rehabilitation solutions.

He said a lack of industry commitment in the absence of international and local tailings closure standards inhibited the accurate calculation of closure costs, while causing uncertainty surrounding regulatory expectations.

He added that proper consideration of these factors would contribute to the improvement of tailings design practices that would hopefully help to prevent the exacerbation of externalities for future generations.