Mine Tailings Storage: Safety Is No Accident

that neutralize the acidity of drainage water (e.g. successive alkalinity-producing systems (SAPS)) and barrier systems. Improving the quality of contaminated tailings and restoring soils affected by acidmine drainage using biological, chemical, electrokinetic and filtration methods are also being utilized to improve rehabilitation (Schindler et al. 2017). Re-thinking mine tailings Mine wastes, including tailings and waste rocks, can be defined as by-products of mining, mineral processing and metallurgical extraction. They are unwanted, have no current economic value and accumulate at mine sites (Lottermoser 2010). However, some tailings and waste rocks may have an immediate use (Table 5) and this has been recognized since mining and smelting operations first began. For example, European miners in the sixteenth century already reprocessed existing tailings to extract leftover ore minerals. Additionally, the reuse of slag can be traced back to historic times, when the Romans used iron slag in construction, road surfacing and as a flux in the production of iron. Thus, the concept of waste as a resource is not new to the modern

world. Humanity has always pursued mine waste recycling (i.e. the extraction of new value-material and/or conversion of waste to value-added products) and reuse (i.e. the new, beneficial use or application of waste). Yesterday’s waste can become today’s resource. Scientists have important contributions to make by providing the knowledge necessary for the identification of cost-effective reuse and recycling options that can be adopted by industry, and for rational decision-making in critical areas such as waste recycling and reuse. The most pressing challenge facing scientists working on the recycling and reuse of tailings and waste rock is the quantification and distribution of resource ingredients and the environmentally significant elements in these waste products. We must accurately describe mine tailings and waste rock, and understand their properties and processes as well as their short- and long-term behaviour (Lottermoser 2017; Edraki 2014). Unfortunately, many modern concepts of reuse and recycling of tailings and waste rock have remained ideas, theoretical designs or laboratory trials without wider application. These concepts have not been

Reuse and recycling possibilities for tailings and waste rock


Reprocessing to extract minerals and metals; Waste reduction through targeted extraction of valuable minerals during processing; Sand-rich tailings mixed with cement used as backfill in underground mines; Clay-rich tailings used as an amendment to sandy soils and for the manufacturing of bricks, cement, floor tiles, sanitary ware and porcelains; Manganese-rich tailings used in agro-forestry, building and construction materials, coatings, cast resin products, glass, ceramics and glazes; Bauxite tailings used as sources of alum; Cupper-rich tailings used as extenders for paints; Iron-rich tailings mixed with fly ash and sewage sludge for lightweight ceramics; Energy recovery from compost - coal tailings mixtures; Phlogopite-rich tailings for sewage treatment;

Phosphate-rich tailings for the extraction of phosphoric acid; Ultramafic tailings for the production of glass and rock wool; Carbon dioxide sequestration in ultramafic tailings and waste rocks. Source of minerals and metals;

Waste rock

Backfill for open voids; Landscaping material;

Capping material for waste repositories; Substrate for revegetation at mine sites; Aggregate in embankment, road, pavement, foundation and building construction; Asphalt component; Feedstock for cement and concrete; Sulphidic waste rock used as soil additive to neutralize infertile alkaline agricultural soils.

Source: Lottermoser 2011

Table 5. Reuse and recycling possibilities for tailings and waste rocks (Lottermoser 2011)


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