What is the function of quicklime?

Quicklime is not unfamiliar to many people. Quicklime has a wide range of uses. It can be used in building materials, medicine and food. It can dry food or medicine. Lime powder is also divided into many types. Different types can play different roles. Generally, it can also be used for coal and heating.

What is the function of quicklime ?

Quicklime, whose main component is calcium oxide, is usually made by calcining natural rocks whose main component is calcium carbonate at high temperatures, which can decompose them into carbon dioxide and calcium oxide (chemical formula: CaO, quicklime, also known as marble).

Any natural rock with calcium carbonate as the main component, such as limestone, chalk, dolomite limestone, etc., can be used to produce lime.

structure

The main component is calcium oxide (CaO) (Calcium Oxide; Lime; Quick Lime)

Identification: Limestone: Calcium carbonate CaCO3

Calcium hydroxide Ca(OH)2

The main component of limestone is calcium carbonate CaCO3, while the main component of quicklime is CaO.

Quicklime reacts with water to form calcium hydroxide Ca(OH)2, commonly known as slaked lime.

Equation CaO + H2O = Ca(OH)2

preparation

raw material:

In actual production, in order to accelerate the decomposition, the calcination temperature is often increased to 1000-1100℃. Due to the large size of the limestone raw materials or the uneven temperature distribution in the kiln during calcination, lime often contains under-fired lime and over-fired lime. The calcium carbonate in underfired lime is not completely decomposed and lacks bonding power when used. Overburned lime has a dense structure and is often covered with a layer of molten material that dissolves very slowly. Since the production raw materials often contain magnesium carbonate (MgCO3), quicklime also contains a minor component, magnesium oxide (MgO). According to the content of magnesium oxide, quicklime is divided into calcium lime (MgO≤5%) and magnesium lime (MgO>5%).

Production process: The original lime production process is to lay limestone and fuel (wood) in layers and ignite and calcine them for a week. Modern production uses mechanized or semi-mechanized vertical kilns, rotary kilns, boiling furnaces and other equipment. The calcination time is also shortened accordingly. It only takes 2 to 4 hours to produce lime using a rotary kiln, which can increase production efficiency by more than 5 times compared to production using a vertical kiln. In recent years, there have emerged technologies and equipment with significant energy-saving effects, such as cross-flow, double-slope, oil-fired circular vertical kilns and short rotary kilns with preheaters, and the fuel has also been expanded to include coal, coke, heavy oil or liquefied gas.

use

Quicklime is a commonly used desiccant for removing water vapor by chemical absorption. It is also used in steel, pesticides, medicines, desiccants, leather making and alcohol dehydration. It is particularly suitable for puffed food, mushrooms, fungus and other local specialties, as well as products in instrumentation, medicine, clothing, electronics and telecommunications, leather, textile and other industries.

Lime and limestone are used extensively as building materials and are also important raw materials for many industries. Limestone can be directly processed into stone and burned into quicklime. There are two types of lime: quicklime and slaked lime. The main component of quicklime is CaO, which is usually in block form. Pure quicklime is white, and it is light gray or light yellow when it contains impurities. When quicklime absorbs moisture or adds water, it becomes slaked lime, also known as hydrated lime. Its main component is Ca(OH)2. Hydrated lime is mixed into lime slurry, lime paste, lime mortar, etc.