Currently, slag waste generated by primary
zinc and lead smelters must be disposed of in landfills in accordance
with tightening environmental regulations, but competition from
overseas is now fiercer than ever and European producers are looking
for ways to avoid high disposal costs by finding productive uses
for slag. Iron slag is already being used in road building materials,
as an aggregate in concrete and in masonry.
The aim of this project was to develop
new zinc and lead smelting processes for the production of waste
slag with appropriate chemical composition, particle size and morphology
to allow its use in concrete, bricks, tiles and in road construction.
Fundamental to the success of the project was a better understanding
of the leaching mechanism.
Benefits to zinc and lead slag producers
include an estimated 5 MECU in annual slag sales and a 15 MECU reduction
in transport and disposal costs. For end-users, the new materials
represent a superior alternative to sand and other aggregates currently
in use, and depending on availability, potential savings in transportation
costs as well. In environmental terms, the recovery of slag means
natural raw materials can be saved and landfills avoided.