What is Steel Slag
Steel slag is an unavoidable by-product in Iron & Steel making, it is essentially a mixture of metal oxides and silicon dioxide i.e silicate. However, Iron & Steel Slag is non metallic in nature and does not contain hazardous materials. Slag is an alternative construction material with superior environment friendly qualities and better product features. Depending on the stage or type of steel making process, the slag generated is called High Sulphur slag, LD slag (Steel Furnace slag – SFS), LF slag or Electric Arc Furnace (EAF) slag. Steel slag and in particular LD and EAF Slag are being used extensively for various applications in many countries across the world including in USA, the European Union, Brazil, Australia and China.
Varied applications of Steel Slag
Some of the established applications of steel slag outside India include its usage as an aggregate for road construction, as rail ballast, for land and mine fill, in paver blocks and bricks, for cement and for agriculture as a soil conditioner.
In India, use of Steel Slag is very minimal
Current production of steel slag is around 12 million tonnes per annum. However, with steel production on the rise, slag production is also expected to increase manifold. In contrast with other nations, most slag produced in India, especially steel slag, is discarded, however, this is increasingly becoming a problem due to paucity of land; utilization of slag is in the trial phase.
In India, use of slag as aggregate is generally discouraged – ACR Das, Convenor, FICC Steel Sub Group on Slag
Right now, there is no statutory regulation or norm for controlling the slag generation or for utilization of slag. However, sometime in 2003 the MoEF, came up with an innovative idea around steel slag – Corporate Responsibility on Environmental Production (CREP). The initiative aimed at waste minimization through 100% utilization of slag by recycling or reuse by 2008. However, the country has not been able to achieve this target due to the voluntary nature of the initiative and as well due to lack of interest by end-user segments.
It is necessary that steel slag is put to proper use – G Mohan Kumar, Secretary, Ministry of Steel pic.twitter.com/emFsn0FGl3
However, with adequate policy support steel slag can be put to diverse beneficial uses
- Usage of steel slag instead of natural aggregates avoids the environmental footprint of quarrying, and also prevents deforestation
- Steel slag makes roads safer to drive on by offering better skid-resistance and improves safety when used in the asphalt layer. The use of steel slag also provides economies of scale when used in the road construction process, addressing India’s growing infrastructure needs
- Steel slag can be used as a soil neutralizer for highly acidic soils in areas such as Eastern India; it’s use as a fertilizer has also been well-established
- Steel slag has a longer life and durability than natural aggregates when used as rail ballast, thus helping save maintenance costs
- Steel slag is being extensively used in landfills across the world, and is a viable alternative for use in India
Since the policy emphasis is increasingly going towards enhancing housing, roads and other infrastructure, the only way forward is to increase the resource base. The government needs to, on an urgent basis:
- Include slag as an aggregate for infrastructure and construction activities
- Include Slag in Standards & Regulations will go a long way in solving the resource crunch. BIS though has already initiated the process but agenda is long requiring supporting data, study reports and also R&D
- Treat steel slag not as a by-product but as a co-product in the steel making process
- Allot carbon credits to (slag) user departments that can be shared with steel industry
- Identify collaborative research opportunities to identify areas where different quantity & quality of slag can be used, and also,
- Anchor a mission mode approach with all stakeholders to find out optimal use opportunities for steel slag in the Indian infrastructure sector
Unless BIS comes with standards (for slag), it is very difficult for us (government) to put anything in to action