Black ferrous

Ferrous ions (Fe ) combine with sulfide ions (S ) to form black ferrous sulfide FeS) ... 

Hydrogen sulfide also is formed, and this instantly reacts with iron and steel to form thin deposits of black ferrous sulfide in the superheater tubes ... 

The exterior of iron pipes in marshy (anaerobic) soils are often coated with a black film of material that results from a mode of iron corrosion. The ferrous ions produced at the anode react with sulfide present in the anaerobic soil (bacteria may reduce sulfate to sulfide in the absence of oxygen). The black ferrous sulfide is produced by reactions. 

The deposit and corrosion behaviour of water (excepting chemically pure water) is primarily determined by the carbonic acid content in the water. Thus, a carbonic acid content that is too high leads to a stock removal of the so-called black ferrous materials. A carbonic acid content that is too low results in deposits by precipitation of lime (Figure 3.43). 

Figure 3.44 Deposit and corrosion behaviour of water at 17°C, in particular valid for black ferrous material.

SRBs reduce sulfate to sulfide, which usually shows up as hydrogen sulfide or, if iron is available, as black ferrous sulfide (Fig. 10.10). In the absence of sulfate, some strains can function as fermenters and use organic compounds such as pyruvate to produce acetate, hydrogen, and carbon dioxide. Many SRB strains also contain hydrogenase enzymes, which allow them to consume hydrogen. Most common strains of SRB grow best at temperatures from 25 to 35°C. A few thermophilic strains capable of functioning efficiently at more than 60°C have been reported. 

Industrial sectors such as Coal Industry, Iron Ore Mining and Beneficiation, Carbon Black, Ferrous Foundries, and Other Petroleum and Coal Products were included in the Other Industries sector to protect the confidentiality of the information. 

If sulphur is present, a black precipitate of ferrous sulphide is obtained when the ferrous sulphate crystals dissolve. Boil the mixture for about 30 seconds, and acidify with dilute sulphuric acid the ferrous sulphide dissolves and a precipitate of Prussian blue forms if nitrogen is present. 

Typically, dry potassium nitrate is pulverized in a ball mill. Sulfur is milled into cellular charcoal to form a uniform mix in a separate ball mill. The nitrate and the sulfur—charcoal mix are screened and then loosely mixed by hand or in a tumbling machine. Magnetic separators may be used to ensure the absence of ferrous metals. The preliminary mix is transferred to an edge-mimer wheel mill with large, heavy cast iron wheels. A clearance between the pan and the wheels is required for safety purposes. The size of this gap also contributes to the density of the black powder granules obtained. Water is added to minimize dusting and improve incorporation of the nitrate into the charcoal. The milling operation requires ca 3 to 6 h. 

Rea.ctlons, When free (R-R, R -tartaric acid (4) is heated above its melting point, amorphous anhydrides are formed which, on boiling with water, regenerate the acid. Further heating causes simultaneous formation of pymvic acid, CH COCOOH pyrotartaric acid, HOOCCH2CH(CH2)COOH and, finally, a black, charred residue. In the presence of a ferrous salt and hydrogen peroxide, dihydroxymaleic acid [526-84-1] (7) is formed. Nitrating the acid yields a dinitro ester which, on hydrolysis, is converted to dihydroxytartaric acid [617 8-1] (8), which upon further oxidation yields tartronic acid [80-69-3] (9). 

Various methods of home-dyeing cotton and wool materials using natural dyes made from hulls of butternut, hickory nut, pecan, eastern black walnut, and Knglish walnut have been described (149). As far back as during the Civil War, butternut hulls have been used to furnish the yellow dye for uniforms of the Confederate troops. More recent attempts have been made to manufacture yellow and brown dyes from filbert shells on a commercial scale. The hulls are treated with copper sulfate and concentrated nitric acid to produce a yellow color, with ferrous sulfate to produce oHve-green, or with ammonia to produce mby-red (150) (see Dyes AND DYE INTERMEDIATES Dyes, natural). 

Iron Titanates. Ferrous metatitanate [12168-52-4] FeTiO, mp ca 1470°C, density 472(0), an opaque black soHd having a metallic luster, occurs in nature as the mineral ilmenite. This ore is used extensively as a feedstock for the manufacture of titanium dioxide pigments. Artificial ilmenite may be made by heating a mixture of ferrous oxide and titanium oxide for several hours at 1200°C or by reducing a titanium dioxide/ferric oxide mixture at 450°C. 

The black oxides are prepared by the controlled precipitation of Fe O (treat FeSO -7H2 O with NaOH and O2) to form a mixture of ferrous and ferric oxides. 

The ion S " reacts with ferrous Fe ion to form black iron sulfide FeS corrosion product. The hydrogen ions are reduced by electrons produced by anodic reaction in step 1 and form hydrogen atom H ... 

Ferrous gluconate is a black dye. It is composed of iron bound to two molecules of gluconic acid, which is the acid form of glucose. 

Ferrous gluconate is the black dye used to color ripe olives. It is also used as an iron supplement to treat iron-deficiency anemia. 

Fig. 3. Ground state spin (S) and valence delocalization schemes for the known oxidation states of [Fe3S4] clusters. Discrete [Fe3S4] clusters have not been observed in siny protein, but they have been identified as fragments in heterometallic cubane clusters. Reduction of the [Fe3S4]+ cluster by three electrons, to yield a putative aU-ferrous cluster, occurs with the concomitant addition of three protons. Key S , grey Fe +, black Fe +, white Fe, white with central black dot.

Salmonella typhi, in the presence of glucose, reduces bismuth sulphite to bismuth sulphide, a black compound the organism can produce hydrogen sulphide from sulphur-containing amino acids in the medium and this will react with ferrous ions to give a black deposit of ferrous sulphide (Table 1.2). 

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