With given options, choice of refractories is extremely important for smooth running of the kiln. Obvious choice has been basic bricks.
Made in India Basic Refractory Bricks for Cement Kilns
Cement manufacturing has under gone a sea change in the recent past. The wet process which had been the main technique until 1960 has been replaced by dry process. The dry technique with suspension Preheater and later by Preheater with Precalciner helps deal with increased demand in production and energy efficiency requirements, both of which impact refractory selection.
To meet the growing demand of cement world over, particularly in Asian countries, cement manufacturers are under tremendous pressure to increase production at a competitive cost. They now need a longer life of the kiln, with minimum down time and low specific energy consumption. The cement industry has been able to achieve this by installing multistage Preheater with Precalciner upstream of the cement rotary kiln, which has led to transferring the Preheating and calcining reaction from the kiln to the Preheater and Precalciner. The shortened kiln now needs a balanced one-year life to meet the growing demand with minimum energy cost. Further, to decrease fuel cost, cement manufacturers are focusing towards alternative fuels like pet coke, used tyre, oil sludge, municipal waste etc. These and a variety of other influences affect refractories in cement rotary kiln, causing a chemical, mechanical and thermal loading of the lining. To achieve high performance of refractories in the rotary kiln, it is therefore necessary to have a proper understanding of the quality of bricks and location of the bricks in the kiln.
Basic refractory bricks from the Indian refractory pioneer:
Refractories for the cement industry have also progressed with the changing manufacturing techniques. Conventional alumino silicate refractories have made way for more sophisticated basic refractories to cope up with energy efficient ways of manufacturing and to deal with increase in cement production. Increase in demand of clinker production, results in high thermal, thermo mechanical and pyro chemical load, which ordinary refractory bricks fail to stand and need frequent replacement. Since past five decades, basic bricks have been used to line cement kiln where they have proved to be over three times more durable than conventional high alumina bricks.
Dalmia Refractories, a part of the USD 1.5 billion Dalmia Bharat Group has been a pioneer in the entire range of alumino silicate and alumina bearing refractories for the past six decades. With its advanced R&D facilities and dedicated refractory design, application and management teams, Dalmia serves cement customers across the country. Now, with the integration of OCL Refractories, a pioneer in Basic bricks, with the Dalmia Bharat Group, Dalmia Refractories provides the entire range basic bricks apart from tailor made refractory solutions.
The India Advantage:
For top-quality, high-performance Basic Refractory Bricks for cement rotary kilns in India, so far there was no choice but to turn to imports. Aside from currency related challenges, this also meant that the plant had to maintain unusually high inventories to protect against unforeseen delays or disruptions in the midst of long delivery cycles. The result - higher-than-necessary investments and poor cost-benefit scenarios. The damage to the inventory due to hydration during prolonged storage could also not be denied.
Dalmia has effectively addressed these challenges by being the only Indian company now to make these top-quality bricks right here in India. Made from imported raw material at OCL Refractories’ state-of-the-art manufacturing facility at Rajgangpur, Odisha, Dalmia’s ‘Made in India’ basic refractory bricks are at par with the best in the world in terms of quality, finish and performance.
More importantly, customers now have the option to choose to lower and unlock their investments, pay in local currency, manage inventories smartly thanks to shorter local delivery cycles. And last but not the least, customers can get faster service support in view of the geographical convenience, all of which are impediments in the case of imported bricks.
The Dalmia-OCL range of Basic refractory bricks includes:
1.Magnesia Alumina Spinel bricks - Made from high-purity SWM/DBM/FM (Sea Water Magnesite/Dead Burnt Magnesite/Fused Magnesite) and sintered/fused spinel, the environment-friendly Magnesia-Alumina Spinel refractory bricks are available both with and without special additives. These bricks are best-suited for application in burning and transition zones of a cement rotary kiln operating under severe conditions with high thermal loads.
2.Magnesia Alumina Spinel bricks with Zirconia - Made from high purity Magnesia, Spinel and Zirconia, these bricks are highly suitable for Burning zones characterised by very high salt infiltration and thermal loads. Their special composition and resulting properties also make them highly suitable for kilns making clinker for white cement plants.
3.Magnesia Chrome bricks - Due to their superior coating ability and high structural flexibility, these bricks are always in much demand for Burning and Transition zones. Special high-iron bearing chromite is added to ferrite-bonded Magnesia to achieve the unique properties of these bricks, including corrosion resistance to clinkering phases and alkali salts infiltration.
4.Chrome free bricks - Manufacturers across the world today are shifting to materials and processes that are environmentally friendly. Refractory technology is also continuously evolving in line with this focus on sustainability. Chrome-free basic bricks are a welcome result of this evolution.
5.Magnesia Hercynite bricks – Dalmia-OCL’s environment-friendly Magnesia-Hercynite refractory bricks are made from special ferrite-bonded Magnesia & fused Hercynite. These bricks are best-suited for Burning and Upper Transition zones of a cement rotary kiln operating at moderate thermal loads.
Overall, these bricks made from high purity Magnesia and Alumina with special additives help in effectively preventing alkali sulphur attacks, corrosion to clinker melt, along with good coating abilities, high structural flexibility, high resistance to thermal and structural spalling. These extend the refractory service life and help cement manufacturers optimize their production without worrying about importing and storing expensive bricks from foreign manufacturers.
Author Dr. B Mishra, Head – R&D, Dalmia Refractories Limited.