Figure 1
(a) Scheme showing the Patriótica Iron Factory, adapted from (Pinho and Neiva, 2012PINHO, F. A.; NEIVA, I. K. A. 200 anos Fábrica Patriótica: a primeira indústria de ferro do Brasil. Belo Horizonte; Vale, 2012. 112 p.); (b) Four reduction furnaces at the Patriotic Iron Factory, section B. In the relic of furnace nº 2, there were two reduction furnaces. On the left side of the furnace's remnant of the furnace nº 1, four heavy pieces of iron were found on the floor. The eyebolt segment was removed from the relic of the furnace nº 3; (c) Photo showing the furnace's exit.
Figure 2
The layout of The Patriótica Iron Factory and the position of the reduction furnaces (see X and red arrows in section B). The black circles represent the "mouth" of the furnaces, and the grey arrows show the position of the water-driven air trompes of the four reduction furnaces (Pinho and Neiva, 2012PINHO, F. A.; NEIVA, I. K. A. 200 anos Fábrica Patriótica: a primeira indústria de ferro do Brasil. Belo Horizonte; Vale, 2012. 112 p.; Eschwege, 1979ESCHWEGE, W. L. Pluto Brasiliensis. Tradução Domício de Figueiredo Murta. Belo Horizonte: Itatiaia; São Paulo: Ed. USP, 1979. 306 p. 2v.).
Figure 3
(a) Profile of the reduction furnace of The Patriótica Iron Factory interpreted by Horstmann and Toussaint (1989)HORSTMANN, D.; TOUSSAINT, F. Two Brazilian iron works of the early 19th century Part 2, Metal and slag analyses. Journal of the Historical Metallurgy Society, v. 23, n. 2, p. 114-119, 1989.; (b) Water-driven air trompes (François, 1843FRANÇOIS, J. M. Recherches sur le gisement et le traitement direct des minerais de fer dans les Pyrénées et particulièrement dans L’Ariege. Paris: Carilian-Goueury et V. Dalmont, 1843. 405p.).
Figure 4
Hammer of a crucible forge, according to a drawing published by Ferrand (1884aFERRAND, P. The iron industry in Brazil (Province of Minas Geraes). Scientific American, New York, v. 430, Mach. 1884.; 1884bFERRAND, P. A Indústria do ferro no Brasil. Annaes da Escola de Minas de Ouro Preto, v. 4, p. 122-139, 1884.). (a) Position of the hammer’s iron head (A) on the floor plan, showing the water wheel (right); (b) A-B cross-section, indicating the position of the iron head in the hammer (left).
Figure 2
The layout of The Patriótica Iron Factory and the position of the reduction furnaces (see X and red arrows in section B). The black circles represent the "mouth" of the furnaces, and the grey arrows show the position of the water-driven air trompes of the four reduction furnaces (Pinho and Neiva, 2012PINHO, F. A.; NEIVA, I. K. A. 200 anos Fábrica Patriótica: a primeira indústria de ferro do Brasil. Belo Horizonte; Vale, 2012. 112 p.; Eschwege, 1979ESCHWEGE, W. L. Pluto Brasiliensis. Tradução Domício de Figueiredo Murta. Belo Horizonte: Itatiaia; São Paulo: Ed. USP, 1979. 306 p. 2v.).
Figure 3
(a) Profile of the reduction furnace of The Patriótica Iron Factory interpreted by Horstmann and Toussaint (1989)HORSTMANN, D.; TOUSSAINT, F. Two Brazilian iron works of the early 19th century Part 2, Metal and slag analyses. Journal of the Historical Metallurgy Society, v. 23, n. 2, p. 114-119, 1989.; (b) Water-driven air trompes (François, 1843FRANÇOIS, J. M. Recherches sur le gisement et le traitement direct des minerais de fer dans les Pyrénées et particulièrement dans L’Ariege. Paris: Carilian-Goueury et V. Dalmont, 1843. 405p.).
Figure 4
Hammer of a crucible forge, according to a drawing published by Ferrand (1884aFERRAND, P. The iron industry in Brazil (Province of Minas Geraes). Scientific American, New York, v. 430, Mach. 1884.; 1884bFERRAND, P. A Indústria do ferro no Brasil. Annaes da Escola de Minas de Ouro Preto, v. 4, p. 122-139, 1884.). (a) Position of the hammer’s iron head (A) on the floor plan, showing the water wheel (right); (b) A-B cross-section, indicating the position of the iron head in the hammer (left).
Figure 5
Eyebolt (LCMHC 188). (a) Sampling; (b) Polished surface of the eyebolt, showing aligned slag inclusions (see dark regions). Optical microscopy, unetched.
Figure 6
Eyebolt (LCMHC 188). (a) Aligned and elongated slag inclusions. The inclusions show at least two phases (dark grey, globules, and medium-dark grey, matrix, regions).Optical microscopy, unetched; (b) Heterogeneous microstructure, showing close to the surface of the bar (see bottom of the figure) the presence of ferritic plates and perlite (dark region between the plates). The interior of the bar shows equiaxial grains of ferrite. The presence of pearlite indicates that the carbon content near the surface is higher than the centre of the iron bar. Etching, Nital 2%.
Figure 7
Eyebolt (LCMHC 188), types of slag inclusions.
(a) Quasi single-phase microstructure inclusion, containing a large volumetric fraction of wüstite (FeO, region 1) in a SiO2-Al2O3-CaO-MgO-K2O-rich vitreous phase matrix; (b) Duplex microstructure inclusion. Region 1 shows the wüstite phase (FeO), and region 2 the SiO2-Al2O3-CaO-MgO-K2O-rich matrix.; (c) Detail of the slag inclusion shown in (b), the matrix features a dual-phase composed of fayalite (2FeO.SiO2) precipitates (main microconstituent) in a vitreous phase matrix; (d) Elongated single-phase microstructure inclusion, featuring a SiO2-Al2O3-CaO-MgO-K2O-rich vitreous phase. Scanning electron microscopy, back-scattered electron image (BEI), and EDS microanalysis (see Table 1). Unetched samples.
Figure 8
FeO-SiO2 phase diagram (Slag, 1995SLAG atlas. 2. ed. Dusseldorf: Verlag Stahleisen GmbH, 1995. 663 p.).
Figure 9
Hammer (LCMHC 193). (a) Sampling position, dotted area (thickness of the hammer is around 46 cm); (b) Polished surface of the, showing the slag inclusions (dark regions) with various sizes and heterogeneous distribution. Optical microscopy without chemical etching.
Figure 10
(a) Hammer (LCMHC 193), slag inclusions. The inclusions show at least two phases (dark grey, globules, and medium-dark grey, matrix, regions). The slag inclusions are not as elongated as the eyebolt’s inclusion . The proportion of the inclusions’ globular phase is higher than the inclusions’ matrix. Optical microscopy without chemical etching; (b) Detail of a slag inclusion showing five phases: (1) wüstite (FeO); (2) magnetite (Fe3O4), (3) fayalite (Fe2SiO4), (4) vitreous SiO2-Al2O3-K2O phase, and (5) ferrite halo. Scanning electron microscopy, back-scattered electron image. Unetched sample.
Figure 11
Fe-O phase diagram, showing the eutectoid decomposition of wüstite (FeO) below 570º C into magnetite (Fe3O4) and ferrite, adapted from (Nadoll and Mauk, 2011NADOLL, P.; MAUK, J. L. Wüstite in a hydrothermal silver-lead-zinc vein, Lucky Friday mine, Coeur d’Alene mining district, U.S.A. American Mineralogist, Lancaster, v. 96, p. 261–267, 2011.).
Figure 12
(a) TTT diagrams of scale thermally grown in dry and wet atmospheres (Li et al., 2018LI, Z.; CAO, G.; LIN, F.; WANG, H.; LIU, Z. Characterization of oxide scales formed on plain carbon steels in dry and wet atmospheres and their eutectoid transformation from FeO in inert atmosphere. Oxidation of Metals, v. 90, p. 337–354, 2018.). In this diagram, the oxide scales can be defined as the following three types: Type I is comprised of the outer Fe3O4 layer and inner FeO layer; Type II includes the outer Fe3O4 layer, a certain amount of eutectoids, and undecomposed FeO; and Type III consists of the outer Fe3O4 layer and the inner eutectoid layer; (b) TTT diagram for magnetite precipitation (Tanei and Kondo, 2016TANEI, H.; KONDO, Y. Phase transformation of oxide scale and its control. Nippon Steel & Sumitomo Metal Technical Report, n. 111, p. 87-91, 2016.). “▲: Precipitation of Fe3O4 from FeO/metal interface, ▀: Eutectoid transformation into Fe3O4 and ferrite, □: Precipitation of granular Fe3O4, : Precipitation of granular Fe3O4 and eutectoid transformation.”