The coal-based rotary kiln is one of the most demanding refractory environments in Indian primary metals. The atmosphere alternates between oxidising in the shell-air injection zone and reducing along the ore-and-coal bed. Sodium and potassium species from ore and coal volatilise in the reducing zone and re-condense on colder brickwork — attacking alumino-silicate refractories through feldspathoid formation and driving accretion, or ring formation, at the boundary temperatures. A continuously rolling charge of iron ore, non-coking coal and reduced sponge grinds the hot-face throughout the campaign. Formulations built against these mechanisms — and installed with the right dry-out and anchor discipline — are what keep DRI campaigns long and unplanned downtime rare.
For DRI, Ellite Materials supplies refractory raw materials and monolithic refractories to coal-based and gas-based sponge-iron plants. The DRI range is formulated in-house, drawing on kyanite-derived sintered mullite (Bajaj Mullite 60), Bajaj Ceramull refractory-grade kyanite and complementary high-alumina and mullite-corundum aggregates — matched to the alkali, abrasion and thermal-cycle loads that DRI service imposes.
Where our DRI refractories go
Coal-based rotary kiln
- Feed end and kiln inlet. Alkali-resistant high-alumina castable or brick lining, formulated for the thermal shock of feed introduction, the abrasion of raw ore and coal chunks, and the alkali condensation that concentrates in the cooler pre-heating zone. Kiln dam and feed chute lined in dense high-alumina castable.
- Kiln body — pre-heating and reducing zones. Mullite-bonded alkali-resistant high-alumina brick or castable, engineered for low porosity and controlled hot strength. Formulation targets: alkali resistance (feldspathoid formation suppressed), thermal-cycle performance, and hot-face abrasion resistance under the moving bed.
- Discharge end and kiln outlet. The highest-temperature zone of the kiln. Dense high-alumina castable of elevated alumina content, engineered for the combined attack of peak temperature, mechanical wear at product discharge, and the transition to cooler service.
- Shell air injection pipes. The annular refractory around the air tubes is a concentrated wear point — oxidation, high temperature and mechanical stress. Supplied as or as dense castable to plant drawing.
Rotary cooler
- Cooler shell lining. Externally water-sprayed cooler with dense high-alumina castable or brick — a less aggressive service than the kiln, but a demanding abrasion environment as the sponge cools while tumbling. Formulation and matrix design tuned for abrasion resistance on our LCC grades.
- Cooler discharge. Dense high-alumina castable for the product-exit zone, engineered against mechanical wear at the transition to conveyors.
Hot-metal and material transfer paths
- Transfer chutes and drop points. Abrasion-resistant low-cement castable — SiC-containing where wear is severe — built on hard mullite and tabular alumina aggregates, controlled bulk density and matrix packing tuned for hot-face abrasion resistance.
Gas-based DRI (Midrex / HYL) support
- Reformer. High-alumina castable and brick for natural-gas reformer walls and hot outlet zones.
- Reduction shaft, transition zone and product cooler. Dense high-alumina brick and castable, alkali-resistant grades where dust chemistry warrants.
Repair, patch and hot maintenance
- Gunning mixes (high-alumina, alkali-resistant) for hot repair of the kiln body and cooler.
- Ramming masses and mortars — air-setting and heat-setting — for anchor pockets, joint repairs and campaign-turnaround work.
The DRI wear mechanisms we formulate against
- Alkali attack. Sodium and potassium oxides volatilise in the reducing zone and re-condense on colder brickwork, forming leucite and kalsilite with attendant expansion, spalling and disintegration. Countered by mullite-bonded, low-porosity, alkali-resistant chemistries and verified by alkali-attack cup testing.
- Accretion and ring formation. Sintered build-up of ore, coal and ash on the hot-face restricts kiln volume and shortens campaigns. Refractory design targets a low-adherence hot-face and stable joint geometry.
- Reducing atmosphere and CO disintegration. Iron-catalysed carbon deposition inside the refractory pore structure disintegrates alumino-silicates over time. Screening for CO resistance is available on request.
- Thermal cycling. Every start-up and shutdown stresses the lining. Formulation targets high thermal-shock resistance without compromising hot strength or alkali resistance.
- Mechanical abrasion. The continuously rolling charge grinds the hot-face throughout the campaign. Aggregate hardness (BMULL60, tabular alumina), matrix packing and the deflocculant system are all specified against the specific ore and coal.
- Coal-ash chemistry. Coal ash — high in silica, alumina, iron and alkalis — attacks the lining. Formulations are matched to the actual coal being used, not a generic average.
Documentation, QC and technical service
Every consignment is accompanied by a certificate of analysis with chemistry and physical properties for the grade supplied. Alkali resistance and abrasion loss test reports are supplied for the alkali-resistant and abrasion-resistant grades. Grade-level typical chemical analysis sheets are available on request.
Application engineers walk the kiln, examine failed lining sections, and specify against what they see. DRI performance is as much about installation and dry-out discipline as it is about chemistry — dry-out schedules, anchor patterns and joint detailing are supplied with every castable order. Post-mortem lining analysis after a completed campaign is offered to plants running a comparative trial.
Complementary raw materials for the DRI supply chain
Refractory formulators and brick makers supplying the DRI sector procure Bajaj Ceramull refractory-grade kyanite for controlled expansion and in-situ mullitisation, and Bajaj Mullite 60 sintered mullite as the aggregate of choice for alkali-resistant hot-face grades. These raw materials are produced at the Bangalore plant and supplied in parallel to formulator customers, as well as consumed in Ellite Materials' own monolithic production.
Bajaj Ceramull kyanite → · Bajaj Mullite 60 →
Why Ellite Materials for DRI refractories
Aggregate-up formulation. Alkali-resistant castables and bricks are built on kyanite-derived mullite (BMULL60) and Bajaj Ceramull kyanite produced in-house. Aggregate consistency, lot-to-lot chemistry, and matrix packing decisions are made under one roof rather than reconciled across suppliers.
50,000 MT per annum combined installed capacity across refractory raw materials and monolithic refractories, from a state-of-the-art Bangalore plant. Sustained supply reliability at the tonnages DRI operations consume, without missed drops during a long campaign.
QC and R&D laboratory. Chemistry, phase analysis, particle size distribution, mechanical strength, thermal expansion and alkali-attack cup testing under one roof, with lot-level traceability from run-of-mine through to the finished refractory.
Technical service through the campaign. DRI performance is as much about installation and dry-out discipline as it is about chemistry. Application engineers walk the kiln at enquiry, specify against the ore chemistry and coal analysis in front of them, and stay engaged through installation and campaign start-up.
Talk to our DRI sales team
Send the application zone, the plant's ore chemistry and coal analysis, kiln dimensions and shell-air pipe count, and the specific reliability or campaign-life problem being addressed. We respond with a formulation recommendation, a supporting spec sheet, and — where the volume warrants it — an on-plant technical visit.
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