Roller Screen, Feeder line Family
In a pelletizing plant, the larger roller screen located at the entrance of the furnace is referred to as the “roller feeder” since its function is not only to screen the pellets but also to feed the good size ones on the grate that will convey the pellets through the different zones of the furnace.
The pellet feeding purpose is probably the most important purpose of this machine. The efficiency of the feeding will have a large impact on the firing of the pellets, the fuel consumption and the quality of the pellets.
All pelletizing plants operating whether with straight travelling grate or grate-kiln induration technologies require an equipment at the feed end of the furnace to:
1- Complete the green iron ore pellet screening to feed only the pellets meeting the dimension specifications inside the furnace. Whether a first stage of screening is available in the balling department or not, this final screening at the furnace is required. We always find a given amount of fines when the pellet load reaches the furnace. Green pellets are soft and breaks on their way between the balling and the induration departments.
2- Distribute the pellets uniformly on the grate and in accordance with the profile specified by the plant process group.
With the straight-travelling grate technologies, the roller feeder also has to discharge the green pellets at the same time as the side protective layer fired pellets. Those fired pellets are fed by two chutes located on each side of the roller feeder. The discharge of the two products, the green pellets and fired pellets, has to be combined to form a consistent bed on the grate
The design of a roller feeder machine has to:
- Provide the maximum screening area. Attention should be given to the large fines/undersize belt conveyor located under the roller feeder which could limits the number of gaps available for fines/undersize screening;
- Fit adequately within the limited room available in the structure of the grate feeding station and between the wide belt feeding the green pellets to the feeder, the off size pellets reject belt conveyor, the fired pellet chutes (with straight travelling grate machines) and the top of the pallet cars/grate;
- Be reliable with high equipment availability rate;
- Maintain consistency in green pellet sizing. Rolls not bend and should not move from their position. Rolls should resist to abrasion;
- Cope with sticking and impact from contaminants;
- Be easy to maintained;
- Be safe and prevent pellet spillage;
- Reduce to the maximum pellet breakage. The drop height at the feed end and discharge end of the roller feeder have to be as low as possible;
- Optimize fluidity of the pellet load moving on the roller surface.
The roller feeder is exposed to more dust and corrosive gases with the proximity of the furnace. It requires heavy duty equipment that would withstand those difficult conditions.
The large width of the roller feeder, 5800 mm for the largest machines produced by Metal 7, adds a challenge in the design of those bigger screens. The strength of the rollers themselves and the driving of such large rolls are among the main complications.
Metal 7 produce rollers for roller feeder for 40 years and the complete roller feeder machine for more than two decades. The designs have been continuously improved supported by significant investment year after year in R&D. Furthermore, they incorporate innovations which originate from those investments in R&D but also from the feedback of end-users from all over the world who handled different material and who encounters diverse challenges.
The roller feeder solution of Metal 7 is unique on account of the following:
- We supply the roller feeder with strong rollers – not subject to deflection – and with higher abrasion resistance;
- All our roller feeder are custom designed to adapt them to the grate feeding station structure and get the maximum out of the space available and reduce the good pellet chute heights,
- We design and manufacture roller feeder that accommodate the lowest diameter rolls available with the largest screening area and largest screening capacity one would find in the industry;
- They are reliable thanks to the high standard of manufacturing and the low maintenance orientation in all our designs;
- We focus also on reducing green pellet breakage (lower pellet drops, EPSILON discharge end, etc.);
- Energy efficient design;
- Lower vibration and noise level;
- Simple design and rapid roller gap adjustment, roller replacement and roller feeder maintenance;
- Critical components are sealed and protected against dust contamination;
- Creative design and use of material for the rollers, chutes, skirtboards, etc.
Dedicated engineering team support you all through the process (design of the solutions, implementation, commissioning and after sale service);
Improvement of green pellet screening leads to very significant for the pelletizing line and for the steel making plants using the pellets.
A better pellet sizing enhances the productivity of the plants with a better circulation of the hot gases in the furnaces. That is the most obvious gain.
Green pellet screening solutions of Metal 7 also provides:
- Larger screening surface allowing higher throughput of the line, the screening capacity being often a bottleneck in plants;
- Higher productivity of the pelletizing plant with a better sizing and superior bed permeability in the surface;
- More cost-effective machines with lower and easier maintenance and higher equipment availability through less maintenance (or calibration) related interruption of the pelletizing line;
- Gain in efficiency: All good pellets go to the induration instead of being wrongly recirculated in the process (wear resistant rolls equal constant gaps);
- Smarter use of the energy. Better sizing reduces the consumption of fuel.
- Better quality: final product is more attractive for the steel making plants with a narrower sizing and better firing of the pellets;
Just for the pelleting plant operation, benefits in terms of millions of dollars per year are attainable with the conversion to a better green pellets sizing system.
Metal 7, a partnership that lasts
Metal 7 is one of Canada's biggest players in the metallic and ceramic coating field. Thanks to its leading expertise, the company stands out from its competitors by proposing extremely sophisticated, high-performance solutions. This competitive edge allows the company to thrive on the international market. The products manufactured in its workshops are used in nearly fifty plants in 20 countries, on all five continents. Metal 7 exports over 70% of its annual production outside Canada.Contact us