Iron extraction

The concentration of most metals in the earth s cmst is very low, and even for abundant elements such as aluminum and iron, extraction from common rock is not economically feasible. An ore is a metallic deposit from which the metal can be economically extracted. The amount of valuable metal in the ore is the tenor, or ore grade, usually given as the wt % of metal or oxide. Eor precious metals, the tenor is given in grams per metric ton or troy ounces per avoirdupois short ton (2000 pounds). The tenor and the type of metallic compounds are the main characteristics of an ore. The economic feasibihty of ore processing, however, depends also on the nature, location, and size of the deposit the availabihty and cost of a suitable extraction process and the market price of the metal. 

Perez de Ortiz, E.S., Dias Lay, M. De L., Gruentges, K., Aluminium and iron extraction by DNNSA and DNNSA-DEHPA reverse micelles, Int. Solvent Extraction Conf. (ISEC 96) Value adding through solvent extraction, Ed. Shallcross, D.C., Paimin, R. Prvcic, L.M., Melbourne, Australia, pp.409-411, 1996. 

Rendita,/. extent of weighting (fabrics), renken, v.t. bend, turn wrench, sprain. Renn-arbeit, /. Iron) direct process, -eisen, 71. malleable iron extracted by the direct process. 

S. Tagaki, S. Kamei, and M. H. Yu, Efficiency of iron extraction from. soil by mugineic acid family phytosiderophores. J. Plant Nutr. 11 643 (1988). 

Hojanas Also called Siurin. An iron extraction process. Magnetite, mixed with carbon-coke breeze and limestone, is heated in a ceramic retort by passage through a tunnel kiln at 1,200°C. Used commercially in Sweden since 1911. See also DR. 

To extract the iron(III) ions, pass 20 ml of a hot 2 M hydrochloric acid solution through the cation exchanger. Gather the solution flowing out from the column in a 250-ml flask. Use the reaction with potassium hexacyanoferrate(II) to check for the completeness of iron extraction. 

Extraction of Inactive Coupons with KTOX Solution. Average iron extraction rates are plotted as a function of cumulative extraction time in Figure 2. Where rates for the altered and unaltered granite differ, the confidence level at which the difference is significant is indicated in brackets. 

The iron extraction rates for both fresh and altered granite decrease for the first 24 h and become the same constant rate for the remaining 24 to 120 h. Thus the iron associated with oxyhydroxides (formed during recent exposure to GGW or during hydro-thermal alteration) is removed during the first 24-h exposure to... 

Figure 2. Average iron extraction rates for fresh and altered Lac Du Bonnet granite as a function of cumulative extraction time.

KTOX. Iron extracted during the subsequent 24 to 120 h is probably associated with the iron-bearing minerals (e.g. magnetite). This hypothesis is consistent with autoradiographic studies described in the following section. 

Raiswell R., Canfield D. E., and Berner R. A. (1994) A comparison of iron extraction methods for the determination of the degree of pyritization and the recognition of iron-limited pyrite formation. Chem. Geol. Ill, 101-110. 

Iron extraction values show that iron speciation varies significantly between layers in the cave (Fig. 6A). Values for amorphous, total, and ferrous iron range from 2.4 to 84 pmol/g. Extraction results indicate a significant amount of goethite in the lower layers of the sequence as determined by total minus ammonium-oxalate extractable iron (52 pmol/g in the bottom yellow layer) (Schwertmann and Taylor, 1977). The upper layers have total iron values represented almost entirely by ammonium-oxalate extractable iron (83 pmol/g in the red layer and 59 pmol/g in the top orange layer) suggestive of ferrihydrite (a necessary precursor to hematite formation). The ferrihydrite in the upper layers is indicative of formation by rapid oxidation of ferrous iron (Schwertmann, 1993). The black layer contains the only cave sediment with a significant amount (42 pmol/g) of extracted ferrous iron. 

Fig. 5. mg/g of iron extracted by the extracting solutions varsus time. Experimental conditions reported in the text... 

Blood Acid digestion iron extraction clean-up by ion exchange thin film deposition TRXF 0.04 ig/mL No data Prange et al. 1989... 

Iron extracted in this way contains many impurities and is called pig iron it may contain up to 5 percent carbon and some silicon, phosphorus, manganese, and sulfur. Some of the impurities stem from the silicate and phosphate minerals, while carbon and sulfur come from coke. Pig iron is granular and brittle. It has a relatively low melting point (about 1180°C), so it can be cast in various forms for this reason it is also called cast iron. 

An interesting aspect of kinetics is tha question of how species interact when multiple extraction inactions occur. Most extractants are not perfectly selective and are capable of extracting several species from a multicomponent equeous solution. Complete equilibrium models should indicate extraction selectivity for a given system at equilibrium, but selectivity may vary considerably in a nonequilibrium process because of rate differences. In fact, iron(UI) can be extracted by some of the copper-chelating extractants, but their effective selectivity for copper is based on the very slow kinetics of iron extraction. 

Steam treatment of FeS hardly impacts on the physico-chemical properties as listed in Table 1. A minor increase in mesopore surface area from 15 to 20 m g can be discerned, which likely can be attributed to some framework iron extraction, leading to defects in the zeolite framework. Subsequent alkaline treatment of the steamed iron-silicalite sample (s-FeS) leads to a slightly lower mesoporosity development as compared to FeS-at (Table 1), but the degree of silicon dissolution is with 690 mgP dramatically lower than upon the treatment of the latter sample (4020 rngf ). The presence of non-framework iron species. 

Singh, K., Chino, M., Nisizawa, N.K., Goto, S., Nakanishi, T., Takagi, S., Mori, S., 1992. Iron extraction efficacy of plant borne mugineic acid family phytosiderophores in Indian calcareous soils. J. Plant Nutr. 15, 1625-1645. 

The objective for this new step was to increase the global zinc extraction by 0.6% with another zinc ferrite leach, and also to increase the iron extraction by partially destroying the jarosites formed in the acid circuit. This produced a higher quality lead-silver residue better suited for high silver recoveries in the subsequent flotation step. Two installed tanks of 80 m capacity were refitted as reactors and one thickener of 500 m capacity, previously used in the counter-current jarosite wash, were connected to form this new step. 

Electro-reduction deserves further attention as, by applying this technique for iron reduction and stripping, neither chemicals, reductive metals or alloys, nor an autoclave is needed. Because D2EHPA is frequently referenced as the standard for iron extraction from acidic sulphate solutions, especially for Fe/Zn separation, we decided to study some aspects of the electro-reduction of Fe (III)-loaded D2EHPA. 

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