What are the components of refractory spraying materials and the commonly used raw materials?

Refractory spray repair material is a relatively fast construction method for repairing or constructing new lining bodies in high-temperature industrial kilns. The amorphous refractory material used for repairing the lining of thermal equipment using spray construction method is called refractory spray repair material. The construction characteristics of this material are: no need for supporting molds, saving labor and effort, fast construction speed, no dust generated during construction, improved working environment, less rebound during construction, and saving raw materials. The disadvantage is that spraying equipment needs to be used, which is expensive.

Refractory spray repair materials are composed of refractory aggregates, chemical binders, and additives with a certain particle size distribution, and are generally classified as thermal or gas hardening materials. The selection of the main material is based on the possible maximum temperature inside the kiln, temperature fluctuation range, slag properties, and the material of the lining itself. The commonly used raw materials include magnesium, dolomite, magnesium chromium, aluminum silicate, zircon, and silicon carbide. Binders include silicates, phosphoric acid or phosphate, polyphosphates, chromates, sulfates, chlorides, asphalt, resins, and cement. In order to improve the construction performance of refractory spraying materials (such as conveying, wetting, plasticizing, adhesion, sintering, etc.), various additives must also be added, such as wetting agents, wetting agents, plasticizers, sintering aids, etc. Common plasticizers include clay and carboxymethyl cellulose. Sintering aids include iron oxide, serpentinite, olivine, etc.

The particle size composition and ultimate particle size of the spraying material should be determined based on the structure of the spraying machine, the thickness of the spraying layer, and different spraying methods. Improper selection of particle size or unreasonable particle size distribution has a significant impact on the adhesion of the sprayed material and the density of the sprayed layer. In general, wet and dry spraying with too coarse or too many coarse particles can lead to a decrease in adhesion rate. Usually, dry spray patching materials have larger critical particle sizes than wet spray patching materials, sometimes reaching 6-7mm or even larger.

Refractory spraying materials can be divided into wet method (mud method) spraying materials, semi dry method (nozzle mixing) spraying materials, and flame method (fusion method) spraying materials according to construction methods; According to the main material of spray repair materials, they can be divided into magnesium oxide, magnesium calcium, magnesium chromium, magnesium carbon, aluminum silicate, and alumina silicon carbide carbon spray repair materials; According to usage conditions, it is divided into converter spray repair materials, electric furnace spray repair materials, steel drum spray repair materials, vacuum degassing furnace (RH, DH) spray repair materials, iron discharge ditch spray repair materials, and high furnace lining spray repair materials.

There are two methods for compacting magnesium based ramming materials at the bottom of electric furnaces: hot repair and cold repair.

1. Bottom compaction method of magnesia ramming material for electric furnace bottom/refractory cement and its operating process

The sintering of compacted materials in a metal furnace is important for sintering compacted materials/refractory cement, and the oven must be well operated.

(1) If necessary, weld a 1mm thin plate covering the surface of the material layer and add waste for smelting.

(2) The 100t electric furnace smelting technology is based on 75%+25% iron smelting waste, divided into two batches of waste. In the first batch without adding molten iron, add materials twice, with each basket feeding 60 tons and a carbon content of about 1%.

(3) The furnace has a reasonable power supply system, and the baking time after power failure is more than 90 minutes. After the minimum flow drying furnace, good foam slag is obtained.