Common construction steps and parameter specifications for refractory castables in dry kilns | Technological frontiers
01. Anchors
1. The commonly used anchoring components for refractory castable construction in dry kilns are all made of heat-resistant stainless steel (1Gr18Ni9Ti), which can be divided into three types according to their length: (1) 250 × 25 × 4mm; (2) 280 × 25 × 4mm; (3) 300 × 25 × 4mm. Please refer to the relevant refractory material drawings for the specific type of anchor used in the construction site.
2. Anchors are generally processed from a single 4mm thick heat-resistant stainless steel plate into lengths of 250mm, 280mm, and 300mm respectively; A rectangular strip with a width of 25mm is manually processed into a "Y" shape, and finally coated with asphalt at its head.
3. The welding of anchor components should be determined according to the temperature of the area, and a pair of fabrics should be laid every 200mm in the length direction around the kiln mouth; The slope, main beam, and low wall of the grate cooler are arranged in pairs every 300mm. Efforts should be made to achieve consistent distance in preparation for placing insulation materials.
02. Setting of expansion joints
1. Regardless of whether the refractory castable undergoes thermal expansion or contraction, expansion joints should be installed.
2. Heating causes shrinkage of refractory castables, and expansion joints can be made using plywood (or other non refractory and thin materials with certain strength); Heating causes expansion, and depending on the magnitude of the expansion, materials can be selected to set up expansion joints. But the refractory castables I use in dry kilns generally shrink when heated.
3. The distance between expansion joints is 1.5~2.0M.
4. When pouring refractory castables, grout should be poured on both sides of the expansion joint at the same time to prevent the set expansion joint from being pushed down by the grout.
03. Mold making
1. The template is generally made of wood and allows for a gap of ≤ 2mm.
2. After the completion of the mold making, the relevant project leader should inspect it, and any non-conforming items should be immediately reworked.
3. Before pouring, wet the wooden mold with water to reduce gaps and facilitate mold removal.
4. The small wooden strips used internally to support the wooden formwork should be removed immediately without affecting the firmness of the formwork. It must be removed at the latest during the pouring process.
5. The height of a single mold cannot exceed 1M to facilitate vibration and construction quality. To ensure progress, material feeding and mold making can be carried out alternately.
04. Preparation before pouring
1. Confirm that the insulation material to be placed has been placed and secured.
2. Confirm that the wooden mold is well molded and secure.
3. Refractory castables should be mixed with a strong mixer and vibrated with a rotating vibrating rod.
4. Confirm that the strong mixer and vibrating rod are in place before pouring.
5. Depending on the distance, 10-25 mortar buckets should be prepared.
6. Confirm that all refractory materials are sufficient and in place.
7. Confirm that there is a dedicated person responsible for weighing, measuring, and adding high alumina cement; There is also a dedicated person for adding glue, and other personnel for transferring the slurry are also in place.
8. The personnel holding the vibration rod are required to be skilled and responsible, preferably migrant workers in this section.
05. Construction vibration method
1. The general part adopts a Φ 35mm vibrating rod, which is convenient for construction and also conducive to the placement of refractory castables; However, some structurally simple and straight parts can be compacted using a Φ 50mm vibrating rod for construction.
2. The vibration should strive for compactness, and the surface of the casting material must be vibrated to release the slurry.