Dust and sludge by-products from steelmaking are a hard-to-solve waste problem for the steelmaker as they require costly processing before they can be recycled. Harsco uses a variety of resource recovery technologies to add value to by-products through blending and processing of different materials.
Many integrated steelmakers recycle their particulate by-products to the sinter plant. However, because of the low volume and poor handling characteristics of the materials, this often results in variations in the composition and homogeneity of the sinter bed with implications for sinter plant productivity.
Ferrous oxides from the caster or rolling mill represent high quality scrap for re-use in steel production. These can be recycled on their own or agglomerated with other by-products, depending on the specification required, to maximize recovery and minimize any impact on production.
Harsco uses blending and micro-pelletizing processes to convert individual by-products into a single homogenized mix, ensuring a consistent feed material.
The final product, carrying the metallics, can be tailored to the recycling application. For instance, in the form of pellets or briquettes. A strict quality assurance program for each production step ensures that the product matches the specification.
For stainless steelmakers, nickel and chromium represent a significant proportion of their variable cost inputs. The valuable alloys contained in EAF dust are therefore an opportunity for resource recovery. Harsco’s patented PLASMINOX® process recovers nickel, chromium and molybdenum units within a variety of dusts, slurries and fines from stainless steelmaking.
Harsco's PLASMINOX® process uses a 7MW DC electric plasma furnace. The smelted end product is a Ni- and Cr-rich alloy which is returned into steelmaking. The solution has improved the sustainability of steelmaking operations, as well as successfully reducing the cost of raw materials and landfill.
The smelting process produces an ingot containing the recovered metallic units. The compact DC furnace plant is located onsite to facilitate quick recovery and transportation back to the customer for recycling into the furnace.
The PLASMINOX® process delivers strong financial and environmental benefits:
Maximizing the internal rate of recycling of by-products reduces raw material costs for stainless steel producers.
Avoidance of landfill cost.