Ferro-manganese

Ferro-alloys Master alloys containing a significant amount of bon and a few elements more or less soluble in molten bon which improve properties of bon and steels. As additives they give bon and steel better characteristics (increased tensile sbength, wear resistance, corrosion resistance, etc.). For master alloy production carbothermic processes are used for large-scale ferro-sihcon, ferro-chromium, ferro-tungsten, ferro-manganese, ferro-nickel and metallothermic processes (mainly alumino and sihco-thermic) for ferro-titanium, ferro-vanadium, ferro-molybdenum, ferro-boron. 

Both silicon and aluminium are added to zinc to control the adverse effects of iron. The former forms a ferro-silicon dross (which may be removed during casting). Aluminium forms an intermetallic compound which is less active as a cathode than FeZn,] . Similarly in aluminium and magnesium alloys, manganese is added to control the iron . Thus in aluminium alloys for example, the cathodic activity of, FeAl, is avoided by transformation of FeAlj to (Fe, Mn)Al/. This material is believed to have a corrosion potential close to that of the matrix and is, therefore, unable to produce significant cathodic activity . 

After dissolution of the alloy in a mixture of concentrated nitric and hydrochloric acids the iron is masked with triethanolamine in an alkaline medium, and the manganese titrated with standard EDTA solution using thymolphthalexone as indicator. The amount of iron(III) present must not exceed 25 mg per 100 mL of solution, otherwise the colour of the iron(III)-triethanolamine complex is so intense that the colour change of the indicator is obscured. Consequently, the procedure can only be used for samples of ferro-manganese containing more than about 40 per cent manganese. 

Procedure. Dissolve a weighed amount of ferro-manganese (about 0.40 g) in concentrated nitric acid and then add concentrated hydrochloric acid (or use a mixture of the two concentrated acids) prolonged boiling may be necessary. Evaporate to a small volume on a water bath. Dilute with water and filter directly into a 100 mL graduated flask, wash with distilled water and finally dilute to the mark. Pipette 25.0 mL of the solution into a 500 mL conical flask, add 5 mL of 10 per cent aqueous hydroxylammonium chloride solution, 10 mL of 20 per cent aqueous triethanolamine solution, 10-35 mL of concentrated ammonia solution, about 100 mL of water, and 6 drops of thymolphthalexone indicator solution. Titrate with standard 0.05M EDTA until the colour changes from blue to colourless (or a very pale pink). 

The above considerations will be illustrated by the simultaneous determination of manganese and chromium in steel and other ferro-alloys. The absorption spectra of 0.001 M permanganate and dichromate ions in 1M sulphuric acid, determined with a spectrophotometer and against 1M sulphuric acid in the reference cell, are shown in Fig. 17.20. For permanganate, the absorption maximum is at 545 nm, and a small correction must be applied for dichromate absorption. Similarly the peak dichromate absorption is at 440 nm, at which permanganate only absorbs weakly. Absorbances for these two ions, individually and in mixtures, obey Beer s Law provided the concentration of sulphuric acid is at least 0.5M. Iron(III), nickel, cobalt, and vanadium absorb at 425 nm and 545 nm, and should be absent or corrections must be made. 

Bums R.G. The uptake of cobalt into ferro-manganese nodules, soils, and synthetic manganese (IV) oxides. Geochim Cosmochim Acta. 1976 40 95-102. 

Pigments. Pigments employed include TiONA Ti02, SCM Chemicals, lot 25-JKSJ, Baltimore, MD 21202 lampblack, lot 97 Pfizer Minerals and Pigments Div., New York, NY 10017 manganese ferrite and copper chromite, Ferro Colors, Ferro Corp., Pittsburgh, PA 15204. 

Nowadays a large number of functional crystals belongs to the TTB family and presents electro-optic, ferro- piezo- pyroelectric properties (e g. the well-known barium sodium niobate Ba2NaNb50i5 (BNN)). In this work iron and manganese based Kx(lvr%(]Vr )i-xF3 fluorides (0.4solid state reaction and characterised by different diffraction techniques in order to investigate their crystalline stmcture. 

Hlawatsch, S., T. Neumann, C.M.G. van den Berg, M. Kersten, J. Harff, and E. Suess. 2002. Fast-growing, shallow-water ferro-manganese nodules from the western Baltic Sea Origin and modes of trace element incorporation. Afar Geol. 182 373-387. 

B. Lorenz2 has shown that it is possible to produce permanganate by electrolysing a solution of caustic potash, if a manganese or ferro-manganese anode be used and a cathode of copper oxide (the positive plate of a cupron cell for example). 

Aumento F. (1969) The Mid-Atlantic Ridge near 45° N. V. Fission track and ferro-manganese chronology. Can. J. Earth Set 6, 1431-1440. 

Fleet A. J., Bostrom K., Laubier L., and Smith K. L. (1983) Hydrothermal and hydrogenous ferro-manganese deposits do they form a continuum The rare earth element evidence. In Hydrothermal Processes at Seafloor Spreading Centers (ed. P. A. Rona). Plenum, New York, pp. 535-555. 

Manganese phosphates with an open framework are very scarce, but the chemistry of new phases in this area is emerging with some recent reports of organically-templated, layered manganese phosphates [82, 83] and a three-dimensional system with narrow channels, NH4MnP04, which orders ferro-magnetically at - 17 K [84]. 

Chester, R, Hughes, M.J. (1967) A chemical technique for the separation of ferro-manganese minerals, carbonate minerals and adsorbed trace elements from pelagic sediments. Chemical Geology 2, 249-62. 

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