Grate cooler plates are the heat-resistant alloy steel elements that form the moving bed of a clinker grate cooler. Hot clinker at 1300+°C drops from the rotary kiln onto the grate plates, which support and transport the clinker while cooling air is blown through narrow slots from below. LIMING manufactures high-temperature alloy grate plates optimized for each cooler zone with superior thermal fatigue and oxidation resistance.
The grate cooler is the critical piece of equipment that receives hot clinker discharged from the rotary kiln at temperatures of 1300-1450°C and cools it to approximately 100°C above ambient for downstream handling and storage. The cooler bed consists of hundreds of individual grate plates arranged in rows. Plates in each row are mounted on grate supports and driven by a reciprocating mechanism that pushes the clinker bed forward. Cooling air is forced through narrow slots in each plate, fluidizing and cooling the clinker as it progresses through the cooler.
The extreme thermal environment of the grate cooler poses unique materials challenges. The hot end (near the kiln discharge) sees clinker at temperatures that can exceed 1300°C, while the cold end handles clinker at a few hundred degrees. The plates are subjected to a combination of high temperature, rapid thermal cycling (as the bed movement exposes plates to alternating hot clinker and cooling air), oxidation, and abrasive wear from the hard, irregular clinker particles. Selecting the correct heat-resistant alloy for each temperature zone is essential for achieving acceptable plate service life.
LIMING manufactures grate cooler plates from premium heat-resistant alloy steels in two primary grades matched to the cooler zone: ZG40Cr25Ni20 for the hot zone and inlet sections where temperatures are highest, and ZGCr26Ni12 for the intermediate and cold zones. All plates are precision investment-cast with carefully engineered slot geometry for optimal air distribution and minimal clinker fall-through.
| Material Grade | Composition | Max Service Temp | Oxidation Resistance | Cooler Zone |
|---|---|---|---|---|
| ZG40Cr25Ni20 | 25% Cr, 20% Ni, balance Fe | Up to 1300°C | Excellent — thick, stable Cr₂O₃ scale | Hot zone (inlet section), first rows |
| ZGCr26Ni12 | 26% Cr, 12% Ni, balance Fe | Up to 1100°C | Very good — stable oxide protection | Intermediate zone, cold zone |
ZG40Cr25Ni20 (also known as HK40 or 310-type alloy) contains high chromium for oxidation resistance and high nickel for austenitic structure stability at elevated temperatures. It forms a thick, adherent chromium oxide scale that protects the base metal from further oxidation — essential for plates at the hot end where oxygen from the cooling air attacks the hot metal surface. ZGCr26Ni12 (HH-type alloy) provides an economical alternative for the cooler's intermediate and cold zones where temperatures are lower but oxidation resistance is still required.
Premium heat-resistant alloy steels, precision investment casting, and zone-matched material selection.
Lost-wax investment casting produces grate slots with exact dimensions — essential for correct air distribution and cooling efficiency.
Hot zone plates in ZG40Cr25Ni20 for maximum temperature and oxidation resistance. Economical ZGCr26Ni12 for cooler later zones.
Chemical composition of every heat verified by optical emission spectrometer. Full material certification provided.
Common plate sizes and patterns stocked. Custom plates manufactured to your drawings with competitive lead times.
| Parameter | Specification |
|---|---|
| Product Type | Grate Cooler Plate — hot, intermediate, and cold zone |
| Material (Hot Zone) | ZG40Cr25Ni20 (25Cr-20Ni, HK40 type) |
| Material (Int/Cold Zone) | ZGCr26Ni12 (26Cr-12Ni, HH type) |
| Manufacturing | Investment casting (lost wax) for precision slot geometry |
| Max Service Temp (Hot Zone) | Up to 1300°C |
| Max Service Temp (Int/Cold) | Up to 1100°C |
| Slot Width | 3-8 mm (dependent on cooler design) |
| Plate Dimensions | Custom per cooler model and zone |
| Surface Finish | As-cast with shot blasting (grate surface) |
| Heat Treatment | Solution annealed for stress relief and carbide dissolution |
| Inspection | Spectrometer chemical analysis, dimensional check, visual inspection |
| Lead Time | 30-60 days (stock items ship immediately) |
Investment casting for dimensional precision and consistent slot geometry in every plate.
Wax patterns produced to exact plate geometry including all slots, holes, and mounting features.
Wax patterns coated with ceramic slurry and stucco to build a refractory shell. Dewaxed in autoclave.
Heat-resistant alloy melted in induction furnace and poured into pre-heated ceramic shells. Spectrometer verified.
Solution annealing to dissolve carbides and relieve casting stresses. Optimizes high-temperature properties.
Shell removal, shot blasting, slot cleaning, dimensional verification, and chemical analysis certification.