Refractory mud

Refractory mud

Refractory mud is a joint material used for laying refractory bricks. It is composed of refractory powder and admixtures and is used for caulking of refractory masonry. As a refractory material widely used in high-temperature industries such as metallurgy, building materials, and petrochemicals, it is highly respected for its excellent refractory performance and stable physical and chemical properties. It is mainly composed of refractory powder, binder and admixture. Almost all refractory raw materials can be made into powder for preparing refractory mud. Ordinary refractory mud is made of refractory clinker powder and an appropriate amount of plastic clay as a binder and plasticizer. Its strength at room temperature is low, and it has higher strength when it forms a ceramic bond at high temperature. Chemically bonded refractory mud uses hydraulic, gas-hardening or thermosetting bonding materials as a binder. It hardens by a certain chemical reaction before the temperature drops below the ceramic bonding temperature.

Material classification of refractory clay

Refractory mud is divided into refractory muds according to the material: clay, high alumina, mullite, silica and other aluminum silicate muds, magnesium, magnesium carbon and other alkaline muds, carbonaceous clay and other refractory muds.

Different materials of refractory clay are used in conjunction with different materials of refractory bricks for masonry, and the operating temperatures also vary to a certain extent.

 

• The refractory slurry used in high alumina bricks is high alumina refractory slurry;

 

• The refractory slurry used in clay bricks is clay refractory slurry;

 

• The refractory slurry used for mullite bricks is mullite refractory slurry or corundum refractory slurry;

 

• The refractory slurry used in silica bricks is silica refractory slurry;

 

• The refractory slurry used in magnesia bricks is magnesia refractory slurry;

 

• The refractory slurry used in magnesia carbon bricks is magnesia carbon refractory slurry;

 

• The refractory slurry used for lightweight refractory bricks shall be made of insulating refractory slurry of the same material;

 

The main refractory raw materials used in aluminum silicate refractory mud are alumina powder of different grades and contents, with other powders, binders and additives added; the main refractory raw materials used in magnesium refractory mud are magnesia sand; the refractory raw materials used in carbon refractory mud are fixed carbon, etc., with other powders and binders added. Refractory muds of different materials use different raw materials and formulas, and the refractory bricks used in masonry are also different.

 

When refractory mud is used in conjunction with refractory bricks for masonry, not only the material problem should be considered, but also the consistency of the refractory mud and the size of the brick joints after masonry should be controlled. The refractory mud used for refractory bricks should be of the same material as possible to ensure the use effect after masonry and avoid affecting the normal operation of the kiln lining.

Refractory clay properties

1. Plasticity:Refractory clay has good plasticity, which makes it more convenient during construction and can adapt to the splicing of bricks of different shapes and the coating of irregular surfaces.
2. Bond Strength:It has high bond strength, which means it can effectively bond the refractory bricks together firmly to form a strong structure.

 

3. Refractoriness:The refractoriness of refractory clay is relatively high, reaching 1650℃±50℃, which enables it to remain stable in high temperature environments and is not easily melted or damaged.

 

4. Slag resistance:It has good slag resistance, which means that the refractory clay can maintain its structure and performance without being destroyed when facing molten metal or other corrosive substances.

 

5. Thermal spalling:Good thermal spalling means that the refractory clay is not easy to peel off when the temperature changes, ensuring the integrity and service life of the structure.

Use of refractory clay

1. Refractory mud can be hardened after being mixed with water. Normally, no other binders need to be added. Some refractory aggregates and powders can be added. If only refractory mud is used, cracks may appear after high temperature. It can be used for bonding and refractory aggregates to make refractory mortar or concrete. It can also be used as lining in various industrial kilns.

 

2. When laying different refractory bricks, refractory mortar of corresponding materials must be used and they must not be mixed.

 

3. Do not use refractory cement and refractory clay together, otherwise it will reduce its use value. The refractory clay should be used immediately after mixing, and the hardened refractory clay cannot be used again.

 

4. The refractory mud should have appropriate viscosity and fluidity to make the gap between bricks as small as possible (even less than 1 mm). The refractory mud on the refractory bricks should fill the entire surface to form a complete expansion joint.
5. The particle size of refractory mud is generally fine-grained refractory mud, and it can also be selected according to the thickness of the mortar joint. The maximum particle size should not be greater than 30% of the thickness of the mortar joint.

Precautions for using refractory clay

Before using refractory mud, the viscosity of the refractory mud and the amount of liquid added (water bonding, phosphoric acid bonding and resin bonding) should be measured first. In principle, the bonding time of the refractory mud must meet the construction and masonry requirements of refractory bricks. The bonding time of the refractory mud depends on the material, size and construction difficulty of the refractory bricks. Generally speaking, the time is 1-1.5 minutes. Drying too fast or too slow will not work. It is too slow to concentrate, and the refractory bricks and refractory bricks cannot be bonded together too quickly. In addition, when the refractory mud is used together with refractory bricks, the fineness of the refractory mud must be kept above 160 mesh. Otherwise, drying too quickly will result in weak adhesion.

In addition, it should be noted that: there are many varieties of refractory mud, and various varieties and brands cannot be mixed. The refractory mud prepared on the same day is best when it is used up. It is not used every other day. The reasonable use of refractory mud depends on the material of the refractory bricks and the construction temperature.

Refractory clay characteristics and applications:

1. Good plasticity, easy construction;
2. High bonding strength and strong corrosion resistance;
3. High refractoriness, up to (1650±50)℃;
4. Good resistance to slag erosion;
5. Good thermal spalling.

Refractory clay is mainly used in coke ovens, glass kilns, blast furnace hot blast furnaces, and other industrial kilns.

Application industries include: metallurgy, building materials, machinery, petrochemicals, glass, boilers, electricity, steel, cement plants, etc.