Introduction to refractory gunning castable

September 10, 2018

The unshaped refractory material used for repairing the lining of the thermal equipment by the spray construction method is called a refractory gunning castable.

 

The refractory gunning castable is composed of refractory aggregates, chemical binders and additives with a certain particle size, and is generally a thermosetting or gas-hard material. The selection of the main material is selected according to the maximum temperature that can be reached in the kiln, the range of temperature fluctuation, the nature of the slag, and the material of the lining itself. Commonly used raw materials are magnesia, dolomite, magnesia, aluminosilicate, zircon and silicon carbide. The binders are silicates, phosphoric acid or phosphates, polyphosphates, chromates, sulfates, chlorides, pitches, resins, and cements. In order to make the refractory spray materials have good construction properties (such as conveying, wetting, plasticizing, adhesion, sinterability, etc.), it is necessary to add various additives such as sizing agents, sizing agents, plasticizers, and sintering aids. Wait. Commonly used plasticizers are clay and antelope methylcellulose. The sintering aids include iron oxide, serpentine, olivine and the like. The particle size composition and limit particle size of the spray material should be determined according to the structure of the sprayer, the thickness of the spray layer and different spray cleaning methods. Improper particle size selection or unreasonable particle grading has a great influence on the adhesion of the spray material and the density of the spray layer. In general, excessive wet and dry spray granules will result in a decrease in adhesion. Generally, the dry spray material has a larger multi-critical particle size than the wet spray material, and sometimes it can reach 6-7 mm or even larger.

 

According to the construction method, the refractory gunning castable is divided into wet method (mud method) spray feeding material, semi-dry method (nozzle mixing type) spray feeding material and flame method (spraying method) spray feeding material; according to the main material of refractory spray material Divided into magnesia, magnesia, magnesia, magnesia, aluminosilicate and alumina SiO-carbon spray, etc.; according to the conditions of use, divided into converter spray, electric furnace spray Feeding materials, spray materials for steel drums, spray materials for vacuum degassing furnaces (RH, DH), refractory spray materials for tapping trenches, and spray materials for blast furnace linings.

 

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