CALDERYS Expertise in DRI

History of sponge iron in india

Indian sponge iron dates back to 1980 when first sponge iron plant was started as Sponge Iron India Limited at Palloncha (AP) which was a coal based plant. The first gas based power plant came up in 1990 by Essar Steel. Though the producers showed interest in setting up gas based plants initially, later only coal based plants caught the imagination of the industrialists due to smaller size, easy access to technology and lower capital cost. The real growth of sponge iron started in the late 1990’s and sustained in 2000’s.

The fast growth of EAF production route in India has lead to a shortage of quality scrap and price volatility in the low quality scrap supply. This volatility is reflected in the demand for DRI. This is particularly true in majority of the Asian countries, where scrap is scarce and relatively expensive and often imported from North America and Europe. Owing to the reasons stated above over the last two decades India has emerged as world’s largest producer of sponge iron using non coking coal as a reductant, primarily based on SL / RN process.

DRI, apart from being a source for Iron provides several advantages over scrap as a feed material for steel making:

  • Sponge Iron comes with exact chemical composition thus enabling steel maker to predict analyses of molten bath.
  • Sponge Iron comes in uniform size hence is easy to handle and allows automatic/continuous charging in furnace.
  • Sponge Iron contains very low level of residual elements and low sulphur.
  • Sponge Iron has a predictable price structure as compared to volatile prices of scrap.
  • It decreases noise level due to arcing in EAF.
  • Unreduced Iron oxide in sponge Iron reacts vigour with C in molten bath and improves heat transfer and homogeneity of bath.

Products & Applications

Refractories for coal based sponge iron

Refractory bricks were the popular choice for coal based sponge iron plants in India till 1980s. Calderys India worked with sponge iron industry to change the Refractories from Bricks to Castables in rotary kilns, ABC, DSC and Coolers. The industry found value in the proposal and went by our recommendations. Since then DRI industry is using monolithic Refractories for all areas of Refractory usage.

The most popular process adopted by coal based sponge iron plants is SL-RN PROCESS:

Products & Applications

Rotary Kilns

Due to our long history in the field as ACC, we have developed good expertise on Rotary kiln operation and Refractories. This understanding enables us to integrate mechanical aspects of kiln with Refractories and work out a solution which will perform under actual operation conditions. This kind of unique experience proved handy in converting Refractory lining in DRI from bricks to complete monolithics. This concept met with wider acceptance and became the new standard in DRI industry. which converted all existing and forthcoming plants to monolithics lining.

With the backing of dedicated team of Engineers, Calderys India proposed for total design, supply and application of Refractories on turnkey basis which caught up with DRI industry immediately as it resulted in single point responsibility.

The castables installed in a rotary kiln are subjected to various stresses viz, thermal, chemical and mechanical.

  • Thermal shock
  • Infiltration of liquid phase
  • Excessive thermal load
  • Infiltration of alkali salts
  • Redox bursting
  • Hydration cracks
  • Thermal expansion
  • Concentric stress cracks
  • Displacements
  • Ovality
  • Pinch at retainer rings

Kiln Refractory-Desired properties:

  • Good Hot Strength-to withstand the stresses
  • Excellent Abrasion Resistance-to withstand abrasion by charge materials
  • Good strength at normal temperatures-to withstand impact load during breaking of Accretion
  • Minimum reaction with Accretion
  • Spalling resistance
  • Optimum thermal conductivity

Calderys India has got wide range of products namely ACCMON 45, ACCMON 60,ACCMON 80,ACCMON DRI-M etc which meet the above requirements and perform consistently. Calderys India were the first to introduce zone wise selection of castables for Kilns as given below.

Calderys India Recommended Products:-

Preheating Zone:

  • ACCMON 45
  • ACCMON 60

Reduction Zone:

  • ACCMON 80

After burning chamber and dust settling chamber (DSC)

Due to frequent failures and falling of bricks in ABC and DSC region, the concept of using castables was standardized. Also with the contours and bends, application of castables was a lot easier and also the quality of workmanship also improved. The key requirements are resistance to carbon monoxide attack, low adherence to carbon soot carried by gases and lower thermal conductivity to reduce heat loss (useful for Waste heat recovery Boiler). In DSC abrasion is the primary cause of wear; where as the same for ABC is fluctuation of thermal load owing to the variability of combustible present in the exhaust gas. Presence of unconverted CO is expected in DSC and the refractory selected, thus, should have co-resistance property.

Calderys India recommended Products:

  • WHYTHEAT C with Calcium silicate back up for ABC/DSC.

Transfer chute and cooler

Though less critical areas than Kiln, it has proven that low cement castables give consistent results. While thermal shock and stresses create problems in cooler, it is the impact and abrasion which create problems in transfer chute.

Calderys India recommended Products:-

  • ACCMON 80

Our unique strength in sponge iron


  • Vast reference list
  • Our understanding of DRI process and equipments and ability to integrate with Refractory knowledge enables us to provide better and effective products and services.
  • Refractory installation expertise
  • Faster delivery
  • Ability to understand & provide add-ons like anchor design & supply and also provide value added services like guidance on kiln related mechanical matters, training, kiln trouble shooting etc.
  • Speedy response of Calderys India through a nation-wide marketing network.

Installation, Commissioning and Turnkey Maintenance

Well aware of refractory and DRI processes, our experienced supervisors and installers provide expert technical guidance and the best suited installation practices to ensure the refractory performance during service.

Calderys India employs dedicated skilled staff and the latest advances in refractory installation equipment. This can be applied to small, large, and turnkey projects alike depending on the requirement. Alternatively, we can support your teams by supervision, project management, equipment, and also direct installation training. Our aim is to ensure the best installation and dry-out of the refractory so that the customer gets maximum performance.

Once in service, the refractory may require specific maintenance which again can be supplied depending on the customer needs. Depending on the situation, services are available on 24 hours per day, 7 days per week, ensuring minimum downtime for the customer—especially for unplanned emergencies.

Turnkey new Projects

Our engineering teams, dedicated to the D.R.I, help customers meet a wide range of requests such as: refractory lining design, heat transfer calculation, quotation, planning, installation and dry-out.

Calderys India is often consulted in the development of a technical solution. Familiar with the specific processes of each type of units, we are able to engineer a refractory solution, provide project management services, and advise on the proper installation techniques for new projects. We have an excellent reputation for providing reliable solutions and thus have created many long-lasting relationships with our customers, end users, and engineering companies which have praised our products. Our strategic partnerships with the customers ensure that we develop market-oriented solutions on regular basis. Decades of our experience and expertise provides us the capability to become your integrated refractory partner and meet all your needs from solution design to implementation.

Calderys in India

Calderys in India

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