Method for recycling iron-containing by-products discharged from coal-based molten ironmaking process, system therefor, and reduced iron agglomeration system
There is provided a method and system for recycling by-products containing large amounts of useful components and discharged in the form of dust and sludge from a coal-based molten iron making process to reuse the by-products in a reduced iron agglomeration process. The system includes: a fluidized reduction furnace reducing fine iron ore; a reduced iron tank connected to the fluidized reduction furnace through a reduced iron discharge pipe for storing the reduced iron and supplying the reduced iron in an agglomeration system; an agglomeration system agglomerating the reduced iron transferred from the reduced iron tank; and a transfer unit transferring compactions of by-products discharged from a molten iron making process through a by-product supply pipe. The compactions of the by-products are supplied to at least one selected from the group consisting of the fluidized reduction furnace, the reduced iron supply pipe, and the reduced iron tank.
1. A method for recycling iron-containing by-products discharged from a molten iron making process in the form of dust and sludge containing moisture, the method comprising:
agglomerating by-products discharged from a molten iron making process to form by-product compactions, wherein the by-products consist of a sludge and a dust both containing iron;
reducing iron ore to form a reduced iron;
mixing the by-product compactions and the reduced iron to form a mixture of the by-product compactions and the reduced iron; and
agglomerating the mixture to form a mixture compaction.
2. The method of claim 1 , wherein the agglomerating of the by-products comprises:
drying the sludge, or a portion of the sludge to form a dried sludge;
preparing a by-product mixture having a predetermined moisture content by mixing the dried sludge with the dust, or with the dust and remaining sludge;
agglomerating the by-product mixture to form agglomerated by-products; and
drying the agglomerated by-products to form the by-product compactions.
3. The method of claim 2 , wherein the drying of the sludge, or the portion of the sludge comprises: adding the dust to the sludge, or the portion of the sludge.
4. The method of claim 2 , wherein the predetermined moisture content is 30 wt % or less.
5. The method of claim 2 , wherein after the drying of the agglomerated by-products, the agglomerating of the by-products further comprises: sorting the by-product compactions to obtain by-product compactions having a particle size of 1 mm to 10 mm.
6. The method of claim 1 , wherein the by-product compactions have a moisture content of 5 wt % or less.
7. The method of claim 1 , wherein the by-product compactions and the reduced iron are mixed at a weight ratio greater than 0:10 but equal to or less than 9:1.
8. The method of claim 1 , wherein the iron ore is reduced in a reduction furnace under a reducing atmosphere.
9. The method of claim 1 , wherein the reducing of the iron ore comprises:
reducing the iron ore in a fluidized reduction furnace under a reducing atmosphere so as to form the reduced iron;
discharging the reduced iron through a reduction furnace discharge pipe;
storing the reduced iron in a reduced iron tank;
supplying the reduced iron from the reduced iron tank to a forceful transfer tank through a reduced iron supply pipe; and
supplying the reduced iron to an agglomeration device.
10. The method of claim 9 , wherein the by-product compactions are supplied to one or more of the fluidized reduction furnace, the reduction furnace discharge pipe, and the reduced iron tank.
11. The method of claim 9 , wherein the by-product compactions are supplied to one or both of the reduced iron supply pipe and the forceful transfer tank.