2. Iron ore agglomeration technologies

Five iron ore agglomeration technologies can be defined: briquetting, nodulization, extrusion, pelletization and sintering. Sintering and pelletization are the most important agglomeration technologies, in this way, in the EU-27, 14 countries operate 34 iron ore sinter plants with 63 iron ore sinter strands, producing in the first decade of the twenty-first century 130 million tons of sinter annually, on its behalf, 6 pelletization plants produce 27 million tons of pellet annually [7]. Here we are going to describe all these agglomeration technologies, with special dedication to pelletizing and sintering as they are the most used worldwide.

#### 2.1. Briquetting

Briquetting is the simplest agglomeration process. Fine grained iron ore is pressed into two pockets with the addition of water or some other binder agent (molasses, starch, or tar pitch) to form briquettes [8]. A traditional application is the agglomeration of coal [8], other example is the agglomeration of ultrafine oxidized dust produced in the ferroalloys industry [9].

#### 2.2. Nodulization

Nodulization is a process like sintering as it does not need a binder agent. The iron ore concentrate is mixed with carbon, and fed into a rotary kiln, where the material is tumbled at high temperature to form nodules [8]. Reached temperature is enough to soften the ore but not to fuse it. Problems of the nodules are the considerable differences in composition and density (they are too dense), and the lack of a well-developed porosity (permeability) which is of great importance for the operation in the blast furnace. This process, as briquetting, is mainly used for the recycling of iron ore wastes in steel plants.
