Synthetic magnetite

Sulfite concentrations for scavenging oxygen ate typically in the 100— 300 mg/L range. Zinc compounds for sulfide scavenging ate used at concentrations of 1.4—14 kg/m (0.5—5 lb/bbl) synthetic magnetite concentrations range to 140 kg/m (50 lb/bbl) and higher if the need arises. 

Salazar-Camacho, C., Villalobos, M., Rivas-Sanchez, M. D. L. L., Arenas-Alatorre, J., Alcaraz-Cienfuegos, J., Gutierrez-Ruiz, M. E. (2013). Characterization and surface reactivity of natural and synthetic magnetites. Chemical Geology, 347,233-245. doi 10.1016/j.chemgeo.2013.03.017... 

Natural and synthetic magnetite occurs most commonly as octahedral crystals bounded by 111 planes and as rhombo-dodecahedra (Fig. 4.24). Twinning occurs on the 111 plane (Tab. 4.1). STM examination of the (100) face of a natural sample... 

Fig. 7.14 Normalized decrease of the magnetization for magnetites of different origin. Whole cells refer to magnetotactic bacteria, extracted to biogenic magnetite extracted form these. The number indicates the size of synthetic magnetite crystals in nm (modified from Moskovitz etal., 1993, with permission).

Sidhu et ak (1981 a) compared the oxidation upon heating, of natural and synthetic magnetites. The coarse, natural magnetites were much more resistent to oxidation and higher temperatures or longer times were needed for it to take place. Hematite was the only oxidation product, which is in agreement with the results quoted above. 

Maroto, A.J.G. (1981) Some observations on the composition and morphology of synthetic magnetites obtained by different routes. J. inorg. nucl. Chem. 43 1489-1493... 

Sidhu, P.S. Gilkes, R.J. Posner, A.M. (1981a) Oxidation and ejection of nickel and zinc from natural and synthetic magnetites. Soil Sci. Soc. Am. J. 45 641-644 Sidhu, P.S. Gilkes, R.J. Cornell, R.M. Posner, A.M. Quirk, J.P. (1981) Dissolution of iron oxides and oxyhydroxides in hydrochloric and perchloric acids. Clays Clay Min. 29 269-276... 

Maghemite can be produced by heating either lepidocrocite or synthetic magnetite, by oxidation of a mixed Fe -Fe ° solution at RT or by heating ferrihydrite (or other Fe oxides) in the presence of an organic substance. 

Heat synthetic lepidocrocite (chap. 6) or synthetic magnetite (chap. 11) in a crucible in a furnace for 2 hr at 250 °C. 

Amosa, M. K., Mohammed, I. A., Yaro, S. A., Arinkoola, A. O., and hzeez, G. O. (2010a) Comparative Analysis of the Efficacies of Ferrous Gluconate and Synthetic Magnetite as Sulfide Scavengers in Oil and Gas Drilling Operations, NAETA Scientific Journal, 61 (3) 117-122. 

Figure 7. Removal of Cr(VI) from solution by reaction with synthetic magnetite for (A) short term and (B) long term reaction. Also shown are the initial Cr(VI) concentrations (dashed lines) and Cr(VI) concentrations in a blank solution with no magnetite (open circles)) (adapted from ref 13).

Figure 8. High resolution TEM images of synthetic magnetite crystals oriented along the <110> zone axis (A) unreacted magnetite (B) magnetite reacted for 5 weeks in 50 pM Cr(VI) at pH 7 (adapted from ref (73).

Catalysts for ammonia synthesis are made by mixing natural or synthetic magnetite and promoters, and melting the mixture in an electric furnace. The cooled mass is broken up, sized, and in some cases pre-reduced before charging to the converter. The particle size is 2 to 10 mm, and the bulk density is in the range of 2.5 to 2.9 kg/liter. A typical chemical composition is as follows 68.4 percent total Fe, 3.16 percent AI2O3, 0.56 percent MgO, 0.50 percent Si02, 3.54 percent CaO, and 0.58 percent K2O. 

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