The VIRA Engineering Vertical Shaft Kiln (VSK) is an energy-efficient and cost-effective solution for small to medium-scale calcination of limestone, dolomite, bauxite, and other minerals. Unlike rotary kilns, VSKs require lower capital investment and occupy less space, making them ideal for developing regions.

The kiln consists of a vertical shaft lined with refractory materials. Raw material is charged from the top, while fuel (coal, coke, gas, or oil) is introduced from the bottom or side. The material moves slowly downward under gravity, undergoing drying, calcination, and cooling in different zones of the shaft.