Researchers use waste slag to create energy and cut emissions

August 18, 2014, US Department of Energy
Researchers use waste slag to create energy and cut emissions
Researchers use waste slag to create energy and cut emissions.

Slag is a molten mixture of process waste ashes from the power and metallurgical industries. In gasification, slag is made from mineral impurities that remain after a carbon feedstock such as coal has been gasified. In metal refining, slag contains impurities removed from a metal while it is refined. Slag is basically waste that is landfilled in many countries, including the U.S. Two researchers at DOE's National Energy Technology Laboratory have found a way to make slag more valuable. They determined that by mixing two particular types of slag at a unique ratio they can generate energy and fuels.

One of the slags is a byproduct of a metallurgical process that is rich in . The other slag contains high levels of vanadium (III) oxide generated during gasification using petroleum coke-based carbon feedstocks. When the two slags, molten at discharge, are mixed together in the presence of carbon dioxide (CO2), the resulting chemical reactions give off a very large amount of heat—enough to turn a turbine and generate electricity. Simultaneously, the same change CO2 into (CO), which can be combusted with oxygen for additional power or used as a raw material for producing chemicals such as synthetic petroleum.

Hydrogen gas, which is useful in chemical manufacturing and industrial applications including fuel cells, can be made from water using the same procedure. The reactions that yield these products are described in an article recently published in the International Journal of Hydrogen Energy.

The most important aspect of the two slag interactions is that, by mixing them while molten in the presence of CO2, the potential exists to reduce the quantity of CO2 entering the atmosphere by converting it into CO, which can be used in a power plant as fuel or by the chemical industry as a raw material, reducing the amount of needed in these processes. That is the real objective of this work—reducing our CO2 emissions.

Explore further: Gasification of oil palm biomass to produce clean producer gas for heat, power generation

More information: Jinichiro Nakano, James Bennett, "CO2 and H2O gas conversion into CO and H2 using highly exothermic reactions induced by mixed industrial slags, International Journal of Hydrogen Energy, Volume 39, Issue 10, 26 March 2014, Pages 4954-4958, ISSN 0360-3199,

Related Stories

Coal gasification demonstrated

October 23, 2012

DOE's National Energy Technology Laboratory (NETL) has developed a molten catalytic process for converting coal into a synthesis gas consisting of roughly 20% methane and 80% hydrogen using alkali hydroxides as both gasification ...

Making Steel Recycling Greener

January 26, 2010

A new process developed by Siemens cuts the energy required to recycle steel and also lowers carbon dioxide (CO2) emissions.

Byproduct of steel shows potential in CO2 sequestration

October 13, 2008

With steelworks around the world emitting huge amounts of carbon dioxide, scientists are reporting that a byproduct of steel production could be used to absorb that greenhouse gas to help control global warming. The study ...

Trash to treasure: Turning steel-mill waste into bricks

May 25, 2011

Scientists are reporting development and successful testing of a promising new way of using a troublesome byproduct of the global steel industry as raw materials for bricks that can be used in construction projects. Their ...

Recommended for you

Fish-inspired material changes color using nanocolumns

March 20, 2019

Inspired by the flashing colors of the neon tetra fish, researchers have developed a technique for changing the color of a material by manipulating the orientation of nanostructured columns in the material.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.