# Rudomain Iron Ore Treatment by High-Temperature Reduction
## 1 Introduction  
Steel production is a process with high energy consumption and high emission production, and it represents approximately 8% of the global demand for energy and 7% (2.6 Gt of CO2) of the total emission from the power system. Therefore, decarbonisation of the metallurgical industry will be the key drive of future changes in metallurgy, which must definitely reflect a significant change in the technological processes involved in the steel production [1; 2; 3; 4]. The greatest challenges will be faced by the so-called integrated metallurgical plants (blast furnace-basic oxygen furnace, BF-BOF) that produce steel from iron ores. Such plants produce approximately 1.7-2.1 tonnes of CO2 emissions per 1 tonne of produced steel [5; 6; 7]. A study [8] that analysed potential methods of decarbonisation in the metallurgical industry identified the most relevant technologies, such as hydrogen-based direct reduction (H2-DR), hydrogen plasma smelting reduction (HPSR), hydrogen flash smelting (HFS), iron bath reactor smelting reduction (IBRSR), electrolysis processes (alkaline iron electrolysis (AIE) and molten oxide electrolysis (MOE)), optimised blast-furnace processes (for example, top gas recycling blast furnace (TGRBF)), or processes for the capture and usage of CO2 (carboncapture and storage (CCS), carbon capture and usage (CCU)). An important indicator is the technology readiness level (TRL), which is indicative in terms of time of the implementation of the obtained knowledge aimed at commercial industrial usage (TRL-9 level) [9; 10; 11; 12; 13]. In the long-term prediction after 2030, it would be appropriate to focus on the production of a directly reduced product in the form of hot briquette iron (HBI) or direct reduction iron DRI (DRI/EAF mini-mill plant), and such a change can lead to significant decarbonization. Currently, there are also weak points of decarbonization: limited availability of raw materials, limited availability of renewable energy, and increased operating costs. The quality of input iron-bearing materials is assessed on the basis of their physical, chemical, and metallurgical properties [14]. There are only a few suitable iron ore minerals out of more than 300 types, and these are primarily oxide-based minerals, such as magnetite-Fe\({}_{3}\)O\({}_{4}\) (72.36% of Fe), hematite or matrite (pseudomorphosis of hematite after magnetite)-Fe\({}_{2}\)O\({}_{3}\) (69.94% of Fe), limonite (62.85% of Fe) (a mixture of hydrated iron oxides, primarily goethite (HFeO\({}_{2}\)), and lepidocrocite (\(\gamma\)-FeOOH, frequently with absorbed elements of vanadium, manganese, cobalt, etc.) [14]. Siderite-based carbonate ores, namely FeO\({}_{3}\) (48.20% of Fe), and silicate-based ores (leptochlorites), e.g., chamosite-(Fe\({}^{2+}\)Mg,Fe\({}^{3+}\))\({}_{5}\)Al(Si\({}_{3}\)Al)O\({}_{10}\)(OH,O)\({}_{8}\) (29.43% of Fe), may also be processed. For the purpose of assessing the quality or value of iron-bearing ores and concentrates, it is necessary to know their Fe contents and undesirable contents of SiO\({}_{2}\) and other additives. High-quality iron ores exhibit high contents of total iron (minimum 63%), a content of Al\({}_{2}\)O\({}_{3}\) of up to 1.3%, SiO\({}_{2}\) of up to 6%, P below 0.04%, and contents of alkalis of up to 0.08% [15]. Undesirable additives mainly include sulphur, phosphorus, zinc, lead, arsenic, copper, sodium, and potassium, which are chemically bound in various minerals [14]. It is necessary to know not only chemical and mineralogical composition of iron ores and concentrates but also their physical properties, in particular moisture, specific gravity, granulometric composition, bulk properties, porosity and specific surface area, mechanical strength, abrasion, compressive strength, and grindability [16]. Granulometry is a parameter that affects air permeability, gas flow intensity, and pressure loss. In terms of peltesation, it affects its final granulometry, segregation of grains, and peltetisation prior to the high-temperature treatment [16].