WO2024013653A1 - Procédé de réduction directe de matériau à base d'oxyde de fer pour la production d'acier, d'éponge de fer ou de fonte - Google Patents
Procédé de réduction directe de matériau à base d'oxyde de fer pour la production d'acier, d'éponge de fer ou de fonte Download PDFInfo
- Publication number
- WO2024013653A1 WO2024013653A1 PCT/IB2023/057092 IB2023057092W WO2024013653A1 WO 2024013653 A1 WO2024013653 A1 WO 2024013653A1 IB 2023057092 W IB2023057092 W IB 2023057092W WO 2024013653 A1 WO2024013653 A1 WO 2024013653A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- briquettes
- iron
- biochar
- reduction
- production
- Prior art date
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 62
- 230000009467 reduction Effects 0.000 title claims abstract description 62
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 239000000463 material Substances 0.000 title claims abstract description 54
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 38
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 35
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 20
- 239000010959 steel Substances 0.000 title claims abstract description 20
- 229910001018 Cast iron Inorganic materials 0.000 title claims abstract description 9
- 235000013980 iron oxide Nutrition 0.000 claims abstract description 38
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 22
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- 239000000446 fuel Substances 0.000 claims abstract description 8
- 239000002028 Biomass Substances 0.000 claims description 15
- 239000004484 Briquette Substances 0.000 claims description 12
- 239000001257 hydrogen Substances 0.000 claims description 12
- 229910052739 hydrogen Inorganic materials 0.000 claims description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 10
- 230000000035 biogenic effect Effects 0.000 claims description 10
- 238000000197 pyrolysis Methods 0.000 claims description 9
- 238000003723 Smelting Methods 0.000 claims description 8
- 229910015189 FeOx Inorganic materials 0.000 claims description 6
- 239000011368 organic material Substances 0.000 claims description 6
- 239000006227 byproduct Substances 0.000 claims description 4
- 239000002893 slag Substances 0.000 claims description 4
- 229920000704 biodegradable plastic Polymers 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims description 3
- 244000215068 Acacia senegal Species 0.000 claims description 2
- 229920002261 Corn starch Polymers 0.000 claims description 2
- 229920000084 Gum arabic Polymers 0.000 claims description 2
- 239000000205 acacia gum Substances 0.000 claims description 2
- 235000010489 acacia gum Nutrition 0.000 claims description 2
- 239000000440 bentonite Substances 0.000 claims description 2
- 229910000278 bentonite Inorganic materials 0.000 claims description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 2
- 238000005242 forging Methods 0.000 claims description 2
- 229910052595 hematite Inorganic materials 0.000 claims description 2
- 239000011019 hematite Substances 0.000 claims description 2
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 claims description 2
- 235000013379 molasses Nutrition 0.000 claims description 2
- 229920001592 potato starch Polymers 0.000 claims description 2
- 229940100486 rice starch Drugs 0.000 claims description 2
- 238000005096 rolling process Methods 0.000 claims description 2
- 239000008120 corn starch Substances 0.000 claims 1
- 239000010802 sludge Substances 0.000 claims 1
- 238000009987 spinning Methods 0.000 claims 1
- 239000011230 binding agent Substances 0.000 abstract description 14
- 238000006722 reduction reaction Methods 0.000 description 55
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 41
- 229910002092 carbon dioxide Inorganic materials 0.000 description 21
- 239000001569 carbon dioxide Substances 0.000 description 21
- 230000008569 process Effects 0.000 description 18
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 14
- 239000000203 mixture Substances 0.000 description 13
- 239000003638 chemical reducing agent Substances 0.000 description 10
- 239000002245 particle Substances 0.000 description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 9
- 241000196324 Embryophyta Species 0.000 description 7
- 239000003345 natural gas Substances 0.000 description 7
- 239000008188 pellet Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 230000001603 reducing effect Effects 0.000 description 6
- 238000005245 sintering Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 239000003610 charcoal Substances 0.000 description 5
- 239000000571 coke Substances 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000011946 reduction process Methods 0.000 description 4
- 239000011819 refractory material Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 2
- 229920001222 biopolymer Polymers 0.000 description 2
- YXTPWUNVHCYOSP-UHFFFAOYSA-N bis($l^{2}-silanylidene)molybdenum Chemical compound [Si]=[Mo]=[Si] YXTPWUNVHCYOSP-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010891 electric arc Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- -1 i.e. Substances 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 239000011147 inorganic material Substances 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910021343 molybdenum disilicide Inorganic materials 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910001341 Crude steel Inorganic materials 0.000 description 1
- 235000019759 Maize starch Nutrition 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000004320 controlled atmosphere Methods 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 235000013312 flour Nutrition 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 235000012054 meals Nutrition 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000010909 process residue Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/244—Binding; Briquetting ; Granulating with binders organic
- C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
Definitions
- the present invention relates generally to technology for the direct reduction of iron oxide-based material, i.e. , material containing iron oxides, for the production of steel, iron sponge or cast iron. More specifically, the present invention relates to a method for direct reduction of iron oxide-based material in the form of briquettes obtained by mixing such material with biochar (also called biogenic charcoal), within a reduction furnace equipped with electrical resistors and/or oxy-fuel burners.
- biochar also called biogenic charcoal
- the entire world steel production is based on the following two ways of obtaining crude steel: 1) remelting scrap iron in electric arc furnaces, and 2) reducing iron ore in shaft furnaces (blast furnaces) or by direct reduction in natural gas and/or hydrogen furnaces.
- Electric arc furnaces mainly work with iron scrap, the quality of which decreases after each smelting cycle due to the progressive metallurgical contamination of the scrap loaded into the furnaces; clean scrap must therefore be used to dilute the metal bath during each smelting cycle.
- the amount of clean scrap iron available is not sufficient to saturate furnace capacity and thus support global economic growth.
- US6409964B1 discloses a method for producing pellets with sufficient hot and cold mechanical strength for use as feedstock for direct reduction furnaces.
- the pellets are made from iron-based material from steelmaking processes (mainly lump iron ore) and carbon material, bound together by means of a binder with a high alumina hydrate content.
- the pellets Due to the pelletising method itself, the pellets require significant consumption of water and natural gas, as well as the use of fine particulate as a starting material, which entails the use and maintenance of costly dedusting plants. In any case, the presence of such fine dust entails risks to human health if it is dispersed into the environment during storage, handling and pelletising.
- US6409964B1 aims at solving this drawback by using iron oxide particulate with a particle size between 0.1 and 6 mm and minimising the fraction with a particle size below 0.1 mm. This, however, forces to use ore with a controlled particle size derived from special preparation and treatment processes, thereby limiting the possibility of using scrap and by-products of the steelmaking process (or other metallurgical processes), as they typically have excessively finer particle sizes ( ⁇ 0.01 mm).
- US6409964B1 also generically mentions the use of briquettes, as an alternative to pellets, without however providing specific indications on the nature and characteristics of such aggregates, in particular on the type of binders used to consolidate the briquettes.
- WO2021/237281A1 discloses a method for the production of briquettes by direct reduction processes, wherein the briquettes are made of iron ore and lignocellulose, with weight percentages of at least 55% and at least 30% respectively, have a volume comprised between 5 and 20 cm 3 , and have a compressive strength greater than 500 N (prior to the reduction processes).
- WO2021/184078A1 discloses a method and a plant for the production of pre-reduced iron (commonly known by the acronym DRI, from Direct Reduced Iron) by heating iron ore briquettes and biomass in a static furnace by means of gas combustion (air/oxygen mixture with an oxygen content of more than 25%, temperature between 700 and 1100°C and holding time of 10-100 h), with metallisation of the product between 80 and 99%.
- DRI Direct Reduced Iron
- EP1996735A2 discloses a method for the direct reduction of iron ore-based material in a reduction furnace, wherein the iron ore-based material is mixed with a reducing material to form briquettes or pellets.
- the aim of this document is to provide a new composition and method for the production of metallic iron from iron ore that does not require coal, charcoal or coke, and to achieve this it proposes to use as a reducing material a material essentially deprived of free carbon, in particular a biomass.
- biomass paper, cellulose, shredded wood, wheat flour, corn meal, grass clippings, etc.
- briquettes are characterised by a high moisture content, due to the high amount of water contained in the biomass that is used to produce the briquettes.
- a drawback related to the high moisture content of the briquettes is that, during the reduction process, the briquettes tend to shatter due to the formation of steam, resulting in a greater dispersion of dust and in a decrease in the quality of the material to be used in the subsequent smelting process.
- WO2021/214167 discloses a method for manufacturing briquettes to be used as material with which to feed reduction furnaces for steel production.
- the briquettes contain ironbased material, preferably iron ore, and pyrolysed biomass, preferably charcoal (or biochar), and are obtained by sintering process, i.e., by high-temperature forming or agglomeration process.
- the biochar contained in the material mixture from which the briquettes are made serves as fuel for the sintering process and thus allows to achieve the goal of performing the sintering process with less fossil fuel consumption.
- the invention is based on the idea of producing, by forming at a temperature not exceeding 45°C, briquettes made of a first iron oxide-based material, a second carbon-based material consisting of biochar (i.e. , charcoal of biogenic origin) and a third material acting as a binder, and to use a reduction furnace equipped with electrical resistors and/or oxy-fuel burners to heat said briquettes, in particular to a temperature comprised between 1050°C and 1450°C, so as to cause the reduction of the iron oxides contained in said first material of the briquettes by reaction with the carbon contained in the biochar forming said second material of the briquettes.
- a reduction furnace equipped with electrical resistors and/or oxy-fuel burners to heat said briquettes, in particular to a temperature comprised between 1050°C and 1450°C, so as to cause the reduction of the iron oxides contained in said first material of the briquettes by reaction with the carbon contained in the biochar forming said second material
- Figures 1 and 2 are a front view and a side view, respectively, which schematically show a reduction furnace forming part of a plant for the direct reduction of iron oxide-based material according to an embodiment of the present invention.
- the method according to the present invention is based on the idea of heating, within a reduction furnace, briquettes obtained by mixing and forming, at a temperature not exceeding 45°C, iron oxide-based material and carbon-based material consisting of biochar (i.e., charcoal of biogenic origin).
- Iron ore of various origin and quality naturally present in mines such as in particular hematite, i.e., Fe2Os
- the main by-products of steel production and processing methods for example rolling, forging or drawing
- iron oxide-based material also in order to ensure better circularity in the use of steelmaking process residues.
- the coals used must not exhibit special mechanical characteristics. Furthermore, there are no limitations as to the rate of chemical reactivity of the coals which can be used in the method according to the present invention.
- the one charged in blast furnaces must be in the form of sintered material or in the form of pellets, which must neither disintegrate to form dust (which would decrease the permeability of the charge to rising wind) nor stick to the refractory material of the furnace or chemically attack it; in the case of preheaters, only pellets (DRI grades or DRI premium quality) are permitted, which must neither disintegrate to form dust (which would reduce the permeability of the charge to rising wind) nor stick to the refractory material of the preheater or chemically attack it.
- the method according to the present invention does not pose any restrictions on the quality of the ferrous material that is agglomerated with the carbonbased material to form the briquettes with which to feed the reduction furnace.
- the carbon-based material which is used as a reducing agent for the reduction of iron oxides contained in the briquettes, is biochar.
- the biochar is obtained by biomass torrefaction (preferably carried out at a temperature of about 350°C) and/or by biomass pyrolysis (preferably carried out at a temperature between 550°C and 750°C or at a temperature between 950°C and 1050°C).
- biomass torrefaction preferably carried out at a temperature of about 350°C
- biomass pyrolysis preferably carried out at a temperature between 550°C and 750°C or at a temperature between 950°C and 1050°C.
- biochar is obtained by torrefaction and/or pyrolysis of bioplastics (also known as biopolymers).
- biochar reduces, of course, the environmental impact of the method.
- biochar obtained by torrefaction or pyrolysis of biomass makes it possible to reduce the amount of energy required for the reduction and smelting process, as well as to reduce the amount of carbon-based material required for the reduction of iron oxides, since the reducing agent (carbon) is more concentrated and in a more reactive form than when using biomass.
- the ratio by weight of iron oxides to biochar in each briquette calculated according to the relation x(FeO x )/(x(C) + x(FeO x )) 100, where x(FeO x ) is the weight of iron oxides contained in each briquette and x(C) is the weight of biochar contained in each briquette, is between 68% and 84% depending on the type of biochar used.
- this ratio will be 75%
- this ratio will be 80%
- this ratio will be 84%
- the briquettes contain, in addition to the iron oxide-based material and the biochar, a binder whose function is to ensure the agglomeration or consolidation of the briquettes, ensuring mechanical strength values (at least greater than 4 MPa, preferably greater than 10 MPa) suitable for the storage and/or handling of the briquettes.
- the quantity of binder corresponds by weight to no more than 5-8% of the weight of the briquette.
- the binder contains organic material of biogenic nature, for example maize starch, potato starch and/or rice starch, molasses, gum arabic, biopolymer.
- the amount by weight of organic material of biogenic nature used as a binder is no more than 5% of the weight of the briquette.
- an inorganic material in particular bentonite, may also be used as a binder.
- the amount of inorganic material by weight is no more than 3% of the weight of the briquette.
- binders leads to the following main advantages during the process of smelting and reduction of the briquettes: 1) absence of chemical elements that would lead to the formation of slag on top of the metal bath, 2) increase in the efficiency of the reduction of the oxides, as a result of the generation of carbon monoxide and hydrogen, and 3) as a consequence of the second point, decrease in actual CO2 emissions in proportion to the amount of hydrogen generated.
- the carbon and hydrogen atoms of the organic binder may also participate in the reduction process.
- the briquettes may also contain, in addition to the biochar, metals capable of having a reducing action on iron oxides (for example Mn, Si, Al, Ti, Ca, Mg).
- metals capable of having a reducing action on iron oxides for example Mn, Si, Al, Ti, Ca, Mg.
- the stoichiometric ratio must ensure that there are sufficient atoms of the reducing agent to allow the complete removal of the oxygen atoms combined with the iron, according to the following reactions:
- the production of briquettes is carried out through the following steps.
- iron oxide material and biochar with a particle size of less than 500 pm are mixed together. If the starting material has a larger particle size distribution, it is first ground and/or crushed in order to reduce its size below the 500 pm limit. After mixing, the binder is added and the resulting mixture is fed into a special mould to obtain briquettes of the desired shape and size. In order to maximise the mixing efficiency and thus obtain a mixture that is as homogenous as possible, mechanical mixers can be used.
- the final geometry of the briquette may be of various shapes (for example cylindrical, "pillow-like", spherical) and sizes in order to meet the dimensional and mechanical requirements for proper storage and handling of the product.
- the briquettes will have a volume of no more than 65 cm 3 .
- the briquettes may be made as parallelepipeds with dimensions 50 mm x 50 mm x 25 mm.
- the highest mechanical strength values have been found where the largest weight fraction (i.e., the iron oxide-based material) has a larger particle size (in particular, a particle size between 63 pm and 125 pm) than the carbon-based material (in particular, a particle size smaller than 63 pm).
- the briquettes are formed at room temperature, or more generally at a temperature not exceeding 45°C. Therefore, they do not undergo any heating before being loaded into the reduction furnace.
- the briquettes thus produced can be stored and handled at a second site or used at the briquetting site itself, for the production of cast iron and/or iron sponge, in case the reduction furnace is installed at the briquetting site.
- This second option is preferable because, by minimising the distance that the briquettes have to travel to be transported from the production site to the utilisation site, it allows to reduce the total environmental impact of the process, in terms of both pollutant emissions and CO 2 production.
- the briquettes thus obtained are finally fed into a reduction furnace, where they are heated to a temperature between 1050°C and 1450°C, preferably a temperature between 1400°C and 1450°C, in order to cause the softening or smelting of the iron oxides contained in the briquettes and the reduction of these oxides by reaction with the carbon contained in the briquettes (as well as with any additional carbon injected into the furnace).
- the reduction between iron oxides and carbon occurs according to the following reaction:
- the carbon and hydrogen contained in the organic material of biogenic nature used as a binder for the production of the briquettes can also act as reducing agents for the reduction of the iron oxides, according to the following reactions:
- the briquettes also contain metallic residues (for example, Mn, Si, Al, Ti, Ca, Mg) capable of having a reducing action on the iron oxides, then the reduction of the iron oxides will also take place due to these metallic residues, according to the reactions indicated above.
- metallic residues for example, Mn, Si, Al, Ti, Ca, Mg
- FIG. 1 An example of a reduction furnace that can be used for carrying out the present invention is schematically shown in Figures 1 and 2, where it is generally indicated by 10.
- the reduction furnace 10 differs from conventional shaft furnaces (blast furnaces) in that it extends horizontally, instead of vertically.
- This makes it possible to use briquettes with a low compressive strength, for example of the order of 10 M Pa, since there is no layering of the charge in the furnace, which loads with its mass the underlying layers in contact with the liquid phase.
- the walls and basin of the reduction furnace 10 must be made of refractory materials capable of resisting corrosion and fluid-dynamic erosion (Marangoni effect) during the operating period.
- refractory material coated with graphitised carbon, or silicon carbide bricks with graphitic binder similar to what is used in modern blast furnaces, or even alumina- and/or mullite-based material alloyed with SiAION, traditionally used in blast furnace basins.
- the reduction furnace 10 operates by means of electrical resistors 12, which may be silicon carbide (SiC) electrical resistors and/or molybdenum disilicide (MoSi 2 ) electrical resistors and/or graphite electrical resistors (in the event that a controlled atmosphere with low oxygen concentration, namely with a partial pressure of oxygen below 0.05 atm, is present inside the reduction furnace).
- electrical resistors 12 are supplied with electricity from renewable sources, so that the carbon footprint of the method is reduced - if not even eliminated.
- the reduction furnace may be provided with one or more oxy-fuel burners 14, fuelled with hydrogen and/or biomethane. Also in order to increase energy efficiency, it is advantageously contemplated that the reduction furnace exploits the combustion heat from the recovery of the gases (mainly CO) present at the steel production and processing site. In addition, or as an alternative, the CO produced inside the furnace as a result of the reduction reaction can be exploited, through its post-combustion, to decrease the energy delivered to the reduction furnace.
- the gases mainly CO
- the reduction furnace 10 has a feed door 16 for feeding the briquettes, and one or more porous wall or ducts 20 for insufflating inert gas with which to control the atmosphere in the furnace.
- the gaseous environment within the reduction furnace may be formed by ambient air, by Ar (argon), by mixtures of Ar and CO2, by mixtures of N2 and CO2, by mixtures of N2, CO and CO2, by CO2, or by mixtures of CO and CO2.
- the gas mixture within the furnace is adapted depending on the availability and cost of these gases.
- one of these mixtures can be selected in order to maximise the carbon activity for the reduction of the iron oxides.
- the invention In addition to contributing to the reduction in the production costs, the invention also has the great advantage that it can be carried out using plants that are much more limited in size and much less expensive than those available today on the world market. In addition, the invention makes it possible to reduce, if not even eliminate, the carbon footprint of the steel, iron sponge or cast iron production cycle, thus making the process fully sustainable not only from an economic point of view but also from an environmental point of view.
- the briquettes are produced by forming without heating (at room temperature or at a temperature not exceeding 45°C), when the briquettes are fed into the reduction furnace they still contain biochar (unlike the solution described in WO2021/214167, where the briquettes are produced by sintering process) and thus the biochar contained therein can react with the iron oxides, reducing them, without the need to introduce reducing agents, such as coke, natural gas, syngas, hydrogen or carbon, into the furnace, in addition to the briquettes.
- reducing agents such as coke, natural gas, syngas, hydrogen or carbon
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Abstract
Un procédé de réduction directe de matériau à base d'oxyde de fer pour la production d'acier, d'éponge de fer ou de fonte est décrit, comprenant les étapes consistant à : a) produire, par formation à une température ne dépassant pas 45 °C, des briquettes constituées d'un premier matériau à base d'oxyde de fer, d'un deuxième matériau à base de carbone et d'un troisième matériau agissant en tant que liant, ledit deuxième matériau étant du biocharbon ; et b) chauffer les briquettes ainsi obtenues dans un four de réduction (10) équipé de résistances électriques (12) et/ou d'au moins un brûleur oxy-combustible (14), à une température comprise entre 1 050 °C et 1 450 °C, de manière à permettre la réduction des oxydes de fer contenus dans les briquettes par réaction avec le carbone contenu dans les briquettes.
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IT102022000014527 | 2022-07-11 | ||
IT202200014527 | 2022-07-11 |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1996735A2 (fr) * | 2006-03-13 | 2008-12-03 | Michigan Technological University | Production de fer utilisant des produits renouvelables favorables à l'environnement ou des réducteurs de recyclage |
DE102012109284A1 (de) * | 2012-09-14 | 2014-03-20 | Voestalpine Stahl Gmbh | Verfahren zum Erzeugen von Stahl und Verfahren zum Speichern diskontinuierlich anfallender Energie |
WO2021214167A1 (fr) * | 2020-04-24 | 2021-10-28 | Paul Wurth S.A. | Procédé d'alimentation en matière première d'une installation de frittage |
WO2022115024A1 (fr) * | 2020-11-25 | 2022-06-02 | Hybrit Development Ab | Procédé de production de fer spongieux cémenté |
-
2023
- 2023-07-11 WO PCT/IB2023/057092 patent/WO2024013653A1/fr unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1996735A2 (fr) * | 2006-03-13 | 2008-12-03 | Michigan Technological University | Production de fer utilisant des produits renouvelables favorables à l'environnement ou des réducteurs de recyclage |
DE102012109284A1 (de) * | 2012-09-14 | 2014-03-20 | Voestalpine Stahl Gmbh | Verfahren zum Erzeugen von Stahl und Verfahren zum Speichern diskontinuierlich anfallender Energie |
WO2021214167A1 (fr) * | 2020-04-24 | 2021-10-28 | Paul Wurth S.A. | Procédé d'alimentation en matière première d'une installation de frittage |
WO2022115024A1 (fr) * | 2020-11-25 | 2022-06-02 | Hybrit Development Ab | Procédé de production de fer spongieux cémenté |
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