Lime shaft kilns are stationary vertical kilns where the raw limestone enters at the top and gravity flows through three thermally zoned sections known as the preheating, calcining, and cooling zones. The process heats the limestone from ambient temperature to 900°C, which is the point where the carbon dioxide is driven off, leaving calcium oxide, also known as quicklime. Modern kilns are typically one of three designs: single shaft, annular, or regenerative. Each respective design is progressively more energy efficient, but all are based on a countercurrent flow of hot air rising from the burners in the calcining zone through the downward material flow.
Our standard linings for vertical shaft kilns consist of wear-resistant hot-face linings and thermally efficient backup linings. This combination provides lime producers with an economical and tough refractory lining that can withstand the thermal and mechanical challenges present in a vertical shaft kiln. Our special magnesite bricks, NARMAG®, provide superior strength and abrasion resistance at high temperatures, while our KAST-O-LITE® family of insulating materials provides high-temperature insulation to optimize thermal efficiency.