In the construction and application of lime rotary kilns, refractory castables problems are divided into two categories: one is the problem of castable solidification speed during construction; the other is castable quality problems that occur during the production process.
(1) When constructing the transfer chute and kiln tail castables, it was found that the castables still had no strength after a few days of construction, resulting in rework of the castables in this area.
Problem analysis: Due to various reasons, the project was delayed for several months. However, the castable supplier supplied the castables according to the normal contract period. In addition, the high humidity on site directly caused the castables to fail to solidify due to cement failure and lost strength. After contacting the manufacturer, cement was resupplied, but the castable solidified too quickly again. The reason was that the mixer was far away from the construction site. After the castables were mixed, they began to solidify before being delivered to the construction site, affecting the construction quality.
Solution: Send a small mixer to the kiln, mix the refractory castables directly next to the construction site, and start construction immediately after mixing, which saves the time of transportation and has achieved obvious results.
(2) During the production process, the castables of the transfer chute of the four rotary kilns have been worn and fallen off many times. The local temperature in the middle and lower part of the transfer chute gradually increased, reaching 600℃, and the external steel plate was dark red. After stopping the kiln and observing inside the kiln, it was found that the castables at this location had been worn out, exposing the steel plate, and the anchors were also polished.
The refractory castables in this area are all low-cement castables with an alumina content of 70%, and the previous 400t·d-1 and 600t·d-1 kilns also used castables with the same physical and chemical indicators, and no similar problems occurred. After the castable fell off, the castable manufacturer also sent technicians to the site for processing many times, but no better solution was found. In order not to affect Anshan Iron and Steel's production needs, the manufacturer was replaced, and the re-casting was effective.
After analysis, it was found that the main reason why the castables provided by the original castable manufacturer did not reach their service life was that the strength at medium temperature (1093℃) was insufficient. The technical attachment for ordering clearly indicated that the use temperature of the castables was 1100℃.
Comparing the two products used successively, there are obvious differences in volume density and compressive strength. The aggregate texture of the refractory castables of the original castable manufacturer is loose, while the aggregate texture of the replaced manufacturer is dense, and the formula is also different, so the use effect is also obviously different.
