ScanArc Plasma Technologies, a Swedish company, has a new method for the production of hot metal. The method – called IronArc – is based on plasma technology and produces about half as many emissions of carbon dioxide as the traditional blast furnace process.
“Here in Hofors, we develop cutting-edge technologies in high-temperature plasma. Plasma occurs when a gas is sufficiently heated. The electrons are separated from the nuclei,” says Maria Swartling, a researcher at ScanArc.
“As an example, we can recover the metals and energy from waste, such as dust from metallurgical processes,” says Swartling.
“The latest is to use plasma technology in the production of iron. We see benefits from a climate perspective with this new method.”
Environmental benefits from plasma generators
A plasma generator is a device that transfers electrical energy to a very hot gas. The gas is heated by an arc, and the plasma generator can use virtually any gas. In a plasma generator, 85 to 90 percent of the electrical energy is transferred into heat energy and the plasma can be used for different types of reactions. One example is the melting and reduction of zinc oxide dust that is formed in steel manufacturing.
“Other examples of the environmental benefits of plasma technology is the destruction of ozone-depleting substances, the complete decomposition of organic materials in process gases, the recycling of metals in dust collected in dust filters, and the recovery of metals from ash generated during the incineration of waste,” explains Swartling.
In collaboration with the steel group Ovako, ScanArc has developed a new iron-making method with a very high-energy efficiency. The method consists of a two-step process (see figure). In the first step, raw material is melted consisting of iron oxide (Fe2O3), and in the following stage is the reduction of iron oxide to iron. Energy efficiency is achieved through a combination of heat energy through the plasma generators (PG) and internal combustion of process gas in a newly developed reactor concept.
“For many years, the blast furnace process was completely dominant for the production of iron, but we believe that IronArc has the potential to become a competitive alternative,” says Swartling. “The environmental benefits of plasma technology provide reduced energy consumption and carbon emissions. Also there is no need for coke ovens. In a blast furnace, it is mainly coking plants that provide the most significant environmental impact.”
This opens up the possibility of recovering other metals from secondary products in steel mills. Here, there may be significant environmental benefits as increased recycling of secondary products reduce the need for virgin raw materials.
IronArc has been verified in a pilot project in ScanArc Plasma Technologies’ facility in Hofors. The next step in the development process is a demonstration plant for the production of 40,000 tons of iron per year. The demonstration plant is primarily designed to refine the secondary products to new iron ore, but will also be used to test the iron extraction from various ores.
“This is a long-awaited technological breakthrough. A welcome proof that the Swedish steel industry retains its position in the forefront, with constantly optimized process technology, highly advanced products and specialized services,” says Bo-Erik Pers, President of the trade organization Jernkontoret.
The article was published in April 2013