Mining sector  may now have a possible way to monetize soil regeneration in degraded lands. While deforested areas can only  produce high yields under certain methods, our solutions sequester massive amounts of CO2, produce energy or bio-products creating income in social inclusive models.

Mining companies drive economic growth and progress, but can contribute significantly to environmental degradation if their operations are not carefully managed. As a result, the recent 2 decades have witnessed a global surge in research on post-mining landscape restoration, yielding a suite of techniques including physical, chemical, biological (also known as phytoremediation) and combinations.

The industry itself cannot operate without disturbing land, so it has direct impact on land quality.Especially in the case of opencast mining, where a mineral is fairly close to the surface in a massive or wide tabular body, or the mineral itself is part of the surface soil or rock, surface mining methods are often considered as more economical. The most common surface mining methods such as strip mining, open pit mining, opencast mining and quarrying start from the earth’s surface and keep exposure to the surface during the extraction period. Disruption of the surface significantly affects the soil, fauna, flora and surface water, thereby influencing all types of land use. Additionally, if the operation goes further below the water table, it will affect the near-surface groundwater (Chamber of Mines of South Africa 2008).

 

Opportunities for land restoration

Many mining projects include land restoration alternatives. Frequently, damaged lands are cultivated or reforested in the framework of social responsibility to protect or rehabilitate soils. In this regard, biomass to energy or even agri-industrial projects may be interesting as they could create income by restoring mine lands.

Some techniques and methods we consider include:

- Biochar and biological activity. We use soil amendments, compost, biochar and liming to rehabilitate soil fertility, correct pH, restore biological activity through increments in soil organic matter. Lear more about carbon farming and bioenergy here.

- Regenerative agriculture. We consider nitrogen fixation by legumes, biodiverse crops, perennial grasses, alley cropping and afforestation. The multi-feedstock approach promoted allow developers and mining companies to include biogas, combustion/boilers, gasifiers and biofuels. All our cropping systems and feedstock models allow biodiversity enhancement, erosion control. green covers and carbon sequestration.

- Food & Energy. Our cropping systems can include legumes and grasses, tree planting, bamboo, hemp and many other products with outstanding productivity. The combined systems can include intercropping of legumes or double purpose (e.g. fodder / biomass or grains and wood) with our own planting materials.

- Nurseries and capacity building. Any mining company focusing this approach should include biomass suppliers and capacity building. We help companies to obtain planting materials, produce biof-ertilizers, amend the soils and create a large scale operation with owned or external management to supply feedstock.

 – Out-growers and social inclusive aspects. We tend to work with out-growers, farmers and other stakeholders in order to promote rural employment and diversify risk along logistic chains. Biomass energy can be used also to provide local electricity, pellets and biomass fuels for cooking in the domestic sector or even have synergy with decentralized power and heat production for other sectors (cement, bricks for construction, agri-industry, grain/seed driers, etc.). We train farmers and help developers and companies to reduce feedstock costs by collaborating with local stakeholders and improve gender issues.

- Promotion of aquaculture and green corridors. All pits and pools left by mining companies can become wetlands and promote aquaculture production which has several synergies with thermal anergy, animal feed and can be promoted together. These areas tend to be fragile ecosystems that can be terraformed or even closed and regenerated to avoid mosquitos, restore water streams and improve drainage.

 

Water issues

Water resources and the quality of air are seriously modified by surface mining operations. One problem introduced during surface mining operations is groundwater, which contains dissolved salts derived from the rock that it has been in contact with, and it is characterized according to the concentrations and proportions of combinations of ions that it contains. Impacts of surface mining are often large and unpredicted such as a former zinc-copper mine polluting the environment due to cadmium leachates or a former gold-copper ore causing arsenic pollution of surface waters (Sengupta 1993Sams and Beer 2000Salonen et al. 2003Bell and Donnelly 2006).

Biomass crops can reduce erosion as we explain in several previous studies and posts. Contour farming and perennial habits ensure that soil erosion can be controlled while producing raw materials and very high yields.

Farm in Mulot, where the  farmer has adopted napier grass line contours

 

Related image

Most experiences with perennial grasses show how soil erosion can be controlled. Massive literature and experience backup this.

 

Soil restoration in mining sector, some case studies

Bioenergy Crops is now engaged in Ghana with Village Corps to amend 14,000 hectares of degraded mine lands. The working program expected involves massive amounts of biochar being biologically charged with bacteria and other inocula and used as soil amendment together with nitrogen fixing legumes, cover crops, compost operations and perennial agriculture and tree plantations.  Today’s soil in the so called “Galamsey land” shows a clear trend towards desertification, land abandonment, low yield in traditional crops as show in corn -see photo below – and invasive weeds, bare soil and drainage problems.

Imagen

Imagen

copiaçu pastoImagen

See here some mechanisms and a short presentation about how grasses prevent erosion.

Cases in Australia

Australian mining companies understand land rehabilitation is part of responsible mining. We recognise our responsibility as a temporary custodian of land.  Mine rehabilitation is highly regulated, better implemented and more accountable than ever before.

The industry’s approach to land rehabilitation has improved significantly over past decades. We work to improve rehabilitation methods to ensure mining’s compatibility with current and future land uses such as farming.

Peabody has progressed rehabilitation of its Wilkie Creek site in Queensland’s Surat Basin following the completion of coal mining in 2013 with over 60% of rehabilitation now complete. This includes backfilling of open cut voids, re-shaping of dumps and undergoing demolition and associated works. Included within the final landform planning process are paddocks and cattle watering systems to support the end land use of grazing.

Extensive community engagement continues to inform the planning for post-mine land use with grazing trials, including more than 50 cattle on a rehabilitated backfilled pit, delivering positive results for neighbouring graziers.

Wilkie Creek – 2008 (Left). 2016 (Right)

 

Broken Hill before and after bush regeneration

Broken Hill Commons before and after bush regeneration. Image Albert Morris, hand coloured by Margaret Morris 1938, Image: courtesy the Barrier Field Naturalist Club and Broken Hill Regional Library Image Albert Morris, hand coloured by Margaret Morris 1938, Courtesy Broken Hill Regional Library and the Barrier Field Naturalists

See more case studies in our publication – PDF icon Mine rehabilitation in the Australian minerals industry 25 Feb 2016.PDF