calciners

Calciners are industrial furnaces or reactors designed to remove volatile components from solids by heating, a process known as calcination. Calcination involves the thermal decomposition or dehydration of materials such as carbonates and hydrates, producing a more reactive or economically usable product. The term covers a range of equipment and configurations used across mining, chemical processing, and manufacturing.

Calciners may operate as direct-fired or indirect-fired units and appear in several formats, including rotary calciners, shaft kilns, vertical or tower calciners, and fluidized-bed calciners. They can run in batch or continuous modes. In direct-fired systems, combustion gases contact the material to deliver heat, while indirect-fired systems transfer heat through a wall to limit gas contact with the material, which can improve control of emissions and dust.

Common applications include lime manufacture (transforming limestone to lime), cement production, and various chemical or metallurgical processes that require dehydration, decarbonation, or activation of feeds. In cement technology, calcination is a key chemical step, and plants may house separate calciner units upstream or adjacent to the main kiln (or employ a calcining section within the kiln) to manage heat and residence time.

Materials processed by calciners range from limestone and dolomite to clays and other mineral feeds, as well as hydrated or carbonate-containing substances. Design considerations emphasize heat transfer, residence time, temperature control, and the integrity of refractory linings. Environmental and safety concerns include dust control, and emissions of NOx, SOx, and CO2, as well as energy efficiency and equipment maintenance. Calciners are commonly integrated with or positioned upstream of kilns and other processing units, depending on the process requirements.