Study On Performance Optimization And Application For Taphole Clay Of High Alumina Fly Ash And Forsterite

The paper is based on the performance optimization of high alumina fly ash and forsterite, as well as its application in blast furnace taphole clay.The influence of different mass fraction of high alumina fly ash(0%, 10%, 15% and 20%) on the properties of taphole clay was studied. The research showed that samples with 15% high alumina fly ash additive had the highest bending strength. The result of slag-resistance experiment at 1550℃for 3h under reducing atmosphere indicated that slag resistance declined as high alumina fly ash additive increased, so it's necessary to optimize the performance of the high alumina fly ash.We investigated the phase transformation of high alumina fly ash under the atmosphere of N2 with coke and carbon black as the reducer at different temperatures. Sialon could be synthesized by controlling process conditions, such as ratio between fly ash and carbon source, temperature and sample size. Sialon with Fe was prepared by reducing-nitriding high alumina fly ash at 1450℃for 3h with 200% theoretical value of coke powder as reducer. Sample size had a relatively bigger influence on the extent of reduction and nitridation. Large size samples with powders palletized were more solid, which leading reduction and nitridation inside the samples was insufficient. The study found that diameter should be within 15mm under the circumstance of being held at a certain temperature for 3h, and powder with Si2Al4O4N4 and Al2O3 to subjects could be manufactured by increasing carbon content.Taphole clay samples with Fe-Sialon could obtain good initial strength after being dried at 110℃, and the bending strength increased with the rise of temperature since 1000℃. Samples with 3% Fe-Sialon had the biggest bending strength, which was up to 7.66MPa. Meanwhile, taphole clay with Fe-Sialon had good slag resistance.Non-water taphole clay was prepared by using clay, silicon micro powder, SiC, different size of corundum and mid-temperature asphalt powders as raw materials, adding phenolic resin as binder, 3%～12% nitrided ferrosilicon and Fe-Sialon, respectively. The bending strength, bulk density and slag resistance of the taphole clay were comparatively studied. Fe-Sialon prepared by reducing and nitriding of the high alumina fly ash had the similar effect with ferrosilicon when added into the taphole clay, and it helped reduce the cost.The research of forsterite's dimensional stability and phase transformation at high temperature with carbon showed that volume change was little after calcined at 1200℃, and phase transformation was stable at 1500℃, 1550℃and 1600℃under reducing atmosphere. Bending strength decreased when corundum was replaced by calcined forsterite, but slag resistance was little affected. Grain composition and proper addition of the forsterite replacing corundum and SiC were supposed to be studied in-depth in the further research. The maximum cost reduction of taphole clay is in pursuit with the premise of good service performance. And a new technological approach of efficient use for high alumina fly ash and forsterite will be provided.