Changing the iron ore processing chain
The iron ore being mined globally can approximately be divided equally into boulders and fines. For further processing boulders have to be sized to 10-30 mm for blast furnaces and 6-18 mm for sponge iron plants. Iron ore in a finely ground state is not easily transported or readily processed .The iron ore pelletizing process agglomerates the fine ground ore into pellet using binders. The use of pellets increases the productivity in blast furnace and reduces coke consumption. These benefits along the iron ore processing chain push the global expansion of iron ore pelletizing .
Iron ore pelletizing plants
Two main systems, the Grate-Kiln System and the Straight-Grate system are common to produce the transportation friendly pellets. The process in both systems is similar and comprises three main steps: Raw material preparation, pellet formation and hardening of the pellets. The air temperature during the different thermal processing stages varies between 570 and 2,370°F (300° and 1300°C).
Energy efficient pelletizing
Burners are used to create the thermal energy required for the process. To make the process energy efficient the different amounts of combustion gases required for the different process steps need to be measured and controlled. Gas flow measurement in such an application represents a challenge due to the temperatures and the presence of particles. PROMECON’s McON Air system uses a correlation based technology that can not be plugged by dirt and is drift and maintenance free. The sensors are made of abrasion resistant material so they guarantee a long duty time.
Successful installations at different plants
The PROMECON flow measurement system is operating at three different iron ore pelletizing plants in North America. The systems have been applied together with a Canadian processing technology consulting company. The main focus of those installations was measuring air flow in the recuperator duct. Another time PROMECON systems are used to control the process more precisely and get a more energy efficient thermal processing.