Lime kilns are mainly classified into square kilns and circular kilns. According to the classification of fired products, they can be divided into lime kilns, ceramic kilns, cement kilns, glass kilns, brick kilns, etc. All kinds of kilns can be roughly divided into 3 parts, 1. The preheating zone. 2. Calcined belt. 3. Cooling belt.

The preheating zone is generally located on the top of the furnace roof, and the operating temperature is not high, but it is easy to cause severe wear to the refractory bricks when they are put into the product, and the furnace gas will cause serious chemical erosion to the refractory bricks. Therefore, the preheating zone refractory bricks must have the following properties:

(1) High density.

(2) High compressive strength.

(3) Good wear resistance.

(4) Good corrosion resistance to slag.

(5) Strong anti-peeling ability.

Although the refractory bricks used in the preheating zone do not have high-temperature requirements, they are particularly demanding for other properties of the refractory bricks.

Calcined belt. The calcination zone is the zone where the products and the refractory bricks used in the lime kiln have the strongest chemical reaction, and the calcination zone is also the zone with the highest working temperature. Therefore, refractory bricks for lime kilns must have the following characteristics:

(1) High refractoriness.

(2) Good thermal shock resistance.

(3) Good corrosion resistance.

(4) Good wear resistance.

In the past, high-alumina refractory bricks or clay refractory bricks were generally used in the calcined zone, but recent research results show that the use of basic refractory bricks with good chemical stability will be more effective. However, not all basic refractory bricks are used in the calcination zone. In the parts near the preheating zone and the cooling zone, wear resistance is more important than corrosion resistance, so high-alumina refractory bricks with good wear resistance and high refractory temperature are used.

Cooling belt. Because the burned lime still contains high heat and moves back and forth when it enters the cooling zone, the refractory bricks in the cooling zone should have the following properties:

(1) Good wear resistance.

(2) Resistance to rapid cooling and rapid heating.

(3) Good peeling resistance.

Magnesia-chrome bricks are refractory products with magnesium oxide (MgO) and chromium trioxide (Cr2O3) as the main components, and periclase and spinel as the main mineral components. This type of brick has high refractoriness, high temperature strength, strong corrosion-resistance to alkaline slag, excellent thermal stability, and certain adaptability to acidic slag. The main raw materials for the manufacture of magnesia-chrome bricks are sintered magnesia and chromite. The purity of magnesia raw materials should be as high as possible, and the chemical composition requirements of chromite are Cr2O3: 30～45%, CaO: ≤1.0～1.5%.