The National Cleaner Production Centre supported risk management SMME, Tailor-Made Risk Solutions, to get one step closer to a circular economy business opportunity through the testing of silicomanganese slag generated through the steel manufacturing process for potential use as construction material.
Tailor-Made Risk Solutions focuses on identifying, assessing and mitigating environmental, health, safety and regulatory compliance risks across various industries. The company identified silicomanganese (SiMn) slag stockpiles on a steel mining client’s site that posed a major risk yet could potentially turn into circular economy opportunities. This led Tailor-Made Risk Solutions to approach the NCPC for technical assistance to establish if the slag could be repurposed for construction.
Silicomanganese slag is a byproduct of the ferromanganese alloys that are used in the production of steel. Tailor-Made Risk Solutions currently has access to approximately 6.6 million tons of the slag. This stockpiled material presents a multifaceted challenge, encompassing environmental, economic and regulatory dimensions. Despite its abundant generation, the proper management and utilisation of slag remain underdeveloped, leading to significant disposal burdens and missed opportunities for resource recovery and circularity.
The NCPC made use of the expertise of a specialised laboratory to conduct a series of internationally recognised tests on approximately 600 kg of the slag. The test results revealed that the material has sufficient strength and resilience to be used in road and building construction as a concrete aggregate, with the potential to replace virgin materials such as concrete stones.
The results further confirmed that the material is suitable for use in road construction as a layer before the wearing course (top gravel layer) and can be mixed with in situ material resulting in reduced required quantities.
Internationally, silicomanganese slag has proven a cost-effective, durable and environmentally sustainable alternative to asphalt and cement stones, requiring minimal additional inputs such as water.
The NCPC also analysed the carbon footprint of the slag. The test results indicated that substituting raw concrete stones with silicomanganese slag could reduce GHG emissions by as much as 50%, primarily due to the repurposing of waste that would end up as landfill.
The NCPC is supporting the Tailor-Made initiative as it believes the wider benefits could be significant as a circular economy intervention. Repurposing silicomanganese slag can help to not only mitigate environmental impacts but can also unlock economic opportunities.
