| Currently, the resourceful treatment of molten blast furnace slag (BFS) mainly relies on the water quenching for it. During the rapidly cooling process of molten BFS becoming active raw materials for construction materials making, a great quantity of sensible heat is emitted as waste energy. If molten BFS would be modulated and be centrifugalized (or blown) into slag wool at high temperature, the sensible heat can be utilized efficiently, and at the same time the slag wool products can be used as heat insulating materials needed in urgent, e. g. the outer insulating liner materials for building wall and thermotechnical pipeline. These slag wool products made from BFS have the higher additional value as compared with the other construction materials made from it. Based on the background of above mentioned and aimed at the development of the technology of direct wool producing with molten BFS of Ma Steel, the key issues for this slag wool making process were systematically investigated and the thermal parameters of molten BFS conveying in heat insulation were calculated theoretically in this paper.Firstly, the investigation had been conducted on the acidity coefficient (AC) modulating behavior of BFS and the viscosity changing phenomena of molten modulated BFS. The results showed that modulated BFS with same AC required the amount of modulating agents in order of quartz sand, Tao Chong basalt (TB) and fly ash from the least to the most. Among all three modulating agents, the modulated slag using TB as modulating agent had the lowest liquid temperature at same viscosity (such as at8Pa-s). The liquid temperature was1410℃for TB modulated sample with AC of1.4. As compared with quartz sand and fly ash, the TB used as AC modulating agent would consume more little energy during the process of wool producing with molten BFS.In addition, the viscosity features of molten TB modulated BFS at high temperature could be improved evidently after further potassium feldspar added as fine modulating agent. Above1420℃， after the further adding of2wt.%potassium feldspar, the viscosity of TB modulated slag was lower than commercial mineral wool; which means it had the better wool producing properties than the latter.Secondly, based on the viscosity features of molten modulated BFS, the mineral wool sample was produced used the modulated BFS of Ma steel in centrifugalizing method. The experiment results showed that the fiber diameter was in the relationship with the speed of centrifugalization, and the higher speed caused the thinner fiber diameter. For the quartz sand modulated slag with AC of1.2, its wool sample had the AC value same to this one, and had the average fiber diameter less than7um. The TB modulated slag wool had the fiber diameter size more than7μm. For the quartz sand modulated slag with AC of1.7, its wool sample had apparently different AC value to this one, namely there was the composition segregation for the modulated slag sample during its wool forming process. The wool fiber diameter of quartz sand modulated slag with AC of1.7was bigger than that of the TB modulated slag with the same AC value.Finally, the loss of sensible heat was calculated in simulation for the process of molten BFS conveying using the heat-insulated tank car. The calculated enthalpy value of molten BFS of Ma Steel was1.6×106kJ/t, and this value was equal to the energy comprised in standard coal of54.7kg. When the molten BFS was conveyed by the heat-insulated tank car, the heat emitted rate was0.19%, and the heat loss rate was only23.58%during the whole conveying range of molten BFS from blast furnace to the wool making workshop. Therefore more than75%of sensible heat in molten BFS could be recycled during its conveying process. |
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