Iron ore reducibility
Iron ore reducibility is an important index that can be used to judge the degree of difficulty of ore reduction in the process of smelting. It is an important technical indicator for blast furnace smelting. In the same conditions, the higher the reducibility of the ore, the better the slag-tap permeability, the smaller the coke ratio, and the higher the productivity; similarly, the lower the reducibility, the worse the slag permeability, the higher the coke ratio, and the lower the output.
Generally speaking, there are two aspects to determine the reducibility of iron ore. The first is the mineral composition, the second is the organization structure.
Among the ores, magnetite has the highest reductibility, followed by hematite, while pyrite, siderite and limonite have relatively inferior reductibility, and the amount of slag produced is also large. On the other hand, the arrangement of particles of different mineral compositions has an impact on the reducibility of ore. Mineral particles in the form of embedded lines, clusters or block aggregates are difficult to reduce, and grain breakage worsens this reduction difficulty.
In terms of mineral composition, the reducibility of iron ore depends on the type and amount of gangue minerals contained in the ore. When the ore contains more silicate and carbonate gangue, the reducibility will be lower. In addition, if the ore contains a large amount of phosphorus, then the slag produced will also be acidic due to the decomposition of phosphorus in the iron ore during smelting.
The crushing index is also an important criterion for judging the reducibility of iron ore. Generally speaking, ore with a high degree of breakage has a better reducibility. Because if more mineral particles are exposed to the air, their contact area and activity will be greatly reduced, and their kinetics will be improved under a certain reducing atmosphere, thereby further strengthening their reducibility.
In addition, the reducibility of iron ore also depends on the type and size of the furnace used. Generally, when the size and volume of the furnace are large and the temperature of the gasification increased, the reducibility of the smelted ore will increase.
In summary, due to the variety and complexity of determining factors, the reducibility of iron ore is not a uniform standard. Generally speaking, the slag-tap permeability, coke ratio, and productivity will decrease with the decrease of the reducibility. Therefore, when selecting the furnace for smelting, the reducibility of the ore should be taken into account, and the ore with better reducibility should be selected as much as possible.
