How is lime made?

Lime is a gas-hardened inorganic cementing material, and its main component is calcium oxide. Lime is made of limestone, dolomite, chalk, shells and other raw materials with high calcium carbonate content by calcination at 900 ~ 1 100℃.

The original lime production process is to lay limestone and fuel (wood) in layers and calcine them for one week. In modern times, mechanized and semi-mechanized vertical kiln, rotary kiln, boiling furnace and other equipment are used for production.

The calcination time is shortened accordingly. It takes only 2 ~ 4 hours to produce lime in rotary kiln, which is more than 5 times higher than that in vertical kiln. There are also technologies and equipment with remarkable energy-saving effects, such as cross-flow, double slope, circular vertical kiln burning oil and short rotary kiln with preheater, and the fuel is also expanded to coal, coke, heavy oil or liquefied gas.

Lime curing and hardening:

The process in which quicklime reacts with water to produce calcium hydroxide is called lime digestion. The calcium hydroxide product produced by the reaction is called slaked lime or slaked lime.

When lime solidifies, it releases a lot of heat, and its volume increases by 1.5-2 times. Calcined lime with high calcium oxide content solidifies faster, and its heat release and volume increase are also more.

Depending on the amount of water added, lime can be solidified into mature lime powder or lime paste. The theoretical water requirement for lime solidification is 32% of the weight of lime. Fine and evenly dispersed hydrated lime powder can be obtained by adding 60% ~ 80% water into quicklime.

If you use excessive water for curing, you will get lime paste with a certain consistency. Generally, lime contains calcined lime, which is slow to cure. If the lime slurry is cured after hardening, it will expand and crack due to the expansion caused by curing.