Free download - Vinnova

INNOVATIVE THINKING
From steel pellets
to meatballs
Small balls of iron ore are one reason why the Swedish
production chain from iron ore to finished quality
steel is the most profitable and efficient in the world.
Using pellets instead of ordinary ore makes steel
production more reliable and less energy-consuming.
THE CONVEYOR BELT trundles at the
rate of a few metres per second towards
the top of Furnace 3 at SSAB. Several
thousand tonnes of ore pellets, coke and
lime are poured into the 40 metre high
furnace every day. After eight hours at
a temperature of 2,000° C the iron minerals
are converted into liquid pig iron
that can be tapped from the bottom of
the furnace and be worked into quality
steel.
THE KEY TO SUCCESS
The ore pellets with a diameter of one
centimetre that constitute the raw
material are the key to SSAB’s success.
The process in the blast furnace is
complicated. It requires great precision
to produce high-quality pig iron with
the minimum of energy. Using pellets of
a consistent quality rather than lumps
of ore makes it easier to control the
process, although the size and quality of
the ore pellets must be checked, too.
– But when we get the results of the
day’s slow test the ore is already in the
furnace and it is too late to change the
After eight hours at a temperature
of 2,000° C the iron minerals are
converted into liquid pig iron.
mixture of pellets, coke and slag-forming
materials, explains Robert Johansson,
who is a development engineer.
With the help of the ProcessIT
cooperation project the aim is now to
measure the properties of the pellets at
the same time as the furnace is charged,
thus optimizing the quantity of coke in
relation to the size of the pellets.
– This could save several million euros
a year if we were able to avoid using too
much coke – having too low a temperature
in the furnace might otherwise
mean that we would have to stop production.
John Erik Larsson is the man
who will make this possible. He used to
be a researcher at Luleå University of
Technology and runs an optical metrology
business called MBV Systems.
– Using high-speed measurements
we can create high-resolution threedimensional
images of the pellets while
they are on the conveyor belt. Advanced
calculation methods then tell us the size
distribution and roundness deviations,
which give an indication of the quality
of the pellets.
Iron pellets are a rapidly growing product
that is profitable both for mining and
steel companies. Work is in progress on the
development of a laser-based method for
measuring deviations in the quality of the
small pellets.
FLEXIBLE SYSTEMS
The ore pellets, which consist of finely
ground grains of ore and various binders,
are easy to handle and reduce the
need for treatment steps at the steel
works, explains Lars-Eric Aaro, Director
of Research and Development at
LKAB.
– Ten years ago we only made one
kind of pellet. Nowadays pellets account
for more than 80 per cent of
sales and we have a range of seven
different types that have all been
developed to meet the requirements of
various customers, he says.
John Erik Larsson mentions the
breadth of the ProcessIT project.
– The technology we develop should
not be restricted to the needs of a single
customer. My system can measure
and monitor the quality of everything
from wood chips in heating plants and
pulp plants to meatballs!
V I N N O V A M A G A Z I N E | 1 1