Manganese impurities

Figure 4.12 Secondary neutral and ion mass spectra of a 1 1 Fe-Ni alloy in the mass regions of monomers lop) and dimers (bottom). The dimer distribution indicates that iron and nickel are atomically mixed, as expected in an Fe-Ni alloy. Note the higher sensitivity of SIMS for iron and the manganese impurity (from ter Veen [36]).

Manganese impurities are always found in barite samples and Mn participation in barite luminescence was considered as possible. In order to check this we studied synthetic BaS04 artificially activated by Mn +. Relatively weak green luminescence was foimd (Fig. 5.47a) with a very long decay time of several ms, but such emission has not been found yet in natural barite. 

Amethyst is a variety of quartz (Si02) that is violet to purple in color, probably because of iron and manganese impurities. It measures 7 on the Mohs hardness scale and is obtained from many places, but mainly from India and Brazil. It should not be confused with oriental amethyst, which is a purple native variety of alumina (Al203). 

Zincite is usually colored red or orange by manganese impurities. Photographs of zincite are shown in Fig. 1.2. Zinc oxide crystals exhibit several typical surface orientations. The most important surfaces are the (0001) and (0001) (basal plane), (1010) and (1120) (prism planes) and (1121) (pyramidal plane) crystal faces. In principle, the (0001) planes are terminated by Zn atoms only, while the (0001) surfaces are terminated by oxygen atoms only. However, this simple picture does not hold in reality (see description of the surface structure in Sect. 4.2.1 of this book). Nevertheless, the etching behavior is noticeably different for these two surfaces [17] (see also Chap. 8). 

Colour. The colour of limestone often reflects the levels and nature of the impurities present. White deposits are generally of high purity. Various shades of grey and dark hues are usually caused by carbonaceous material and/or iron sulfide. Yellow, cream and red hues are indicative of iron and manganese. Impurities in marble often produce a variety of colours and patterns. 

The cavity reactor has 3S-in.-thick radial and end reflectors of OkO.. The cavity, wall is -in. A1 oh the radius and i-in. A1 on the ends. Inside dimensions of the cavity are 4-ft. long by 6-ft. diam. The fuel sheets are supported on corrugated aluminum screens within the cavity. A total of 75 kg of aluminum and 273 g of manganese impurity form the structure in the cavity. There are 764 kg (1.0% volume fraction) of structural aluminum inside the DjO region. The heavy water contains 0.22% HtO. One end reflector contains 36 holes (void), -in. diameter, for control rods. This void represents 1.0% of the volume of an end reflector. 

A number of impurities found in compounding ingredients are known to influence the ageing behaviour of rubbers, especially NR. High iron oxide impurity levels, and some forms of copper and manganese impurities are known to be the cause of rapid oxidative degradation. There is little literature available that relates either the active form of impurities or that identifies the level of impurities found in fillers to specific effects on polymer degradation. Nonetheless, it is occasionally an area of concern. It should be noted that every source of filler will be different in its level and type of impurities, so each material must be considered in isolation. Specification values may not be an indicator of performance in polymer. 

Germanium tetrachloride refined for use in making optical fibers is usually specified to contain less than 0.5 to 5 ppb of each of eight impurities vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc. Limits are sometimes specified for a few other elements. Also of concern are hydrogen-bearing impurities therefore, maximum limits of 5 to 10 ppm are usually placed on HCl, OH, CH2, and CH contents. 

The typical SEA process uses a manganese catalyst with a potassium promoter (for solubilization) in a batch reactor. A manganese catalyst increases the relative rate of attack on carbonyl intermediates. Low conversions are followed by recovery and recycle of complex intermediate streams. Acid recovery and purification involve extraction with caustic and heat treatment to further decrease small amounts of impurities (particularly carbonyls). The fatty acids are recovered by freeing with sulfuric acid and, hence, sodium sulfate is a by-product. 

Impurities. Impurities usually found in manganese ore may be classified into metal oxides, eg, iron, 2inc, and copper gangue volatile matter such as water, carbon dioxide, and organic matter and other nonmetaUics. 

The impurity levels in electrolytic manganese metal are as follows ... 

The acid formed then reacts with low grade manganese dioxide ore (65) forming a slurry of impure manganese nitrate to feed the process. 

Electrolytic Oxidation. Electrolytic oxidation of ferromanganese or manganese metal is a one-stage process that circumvents the problem of ore impurities. Moreover, this procedure can be used with low caustic concentrations at room temperature. This process is based on the following... 

In kaolin (clay) processing, sulfur dioxide reduces colored impurities, eg, iron compounds. In the bromine industry, sulfur dioxide is used as an antioxidant in spent brine to be reinjected underground. In agriculture, especially in California, sulfur dioxide is used to increase water penetration and the avadabiHty of soil nutrients by virtue of its abiHty to acidulate saline—alkaH soils (327). It is also usefiil for cleaning ferric and manganese oxide deposits from tile drains (328). 

Cla.riGers. Pool water may occasionally contain metallic impurities such as copper, iron, or manganese which enter the pool with the makeup water or by corrosion of metallic parts in the circulation system. These dissolved metals can discolor the water and cause stains. Chlorine oxidizes soluble Fe and to the highly insoluble Fe(OH)3 and MnO which can be removed by filtration. Water-soluble, high molecular weight polymers can be... 

Cooling by means of evaporative cooling towers is required to maintain a constant temperature of 30—40°C. At higher temperatures, the deposit is rougher, impurity effects are more pronounced, lead codeposition is favored, and the manganese dioxide formed at the anode iacreases and tends to adhere rather than fall to the bottom of the cell. 

Anhydrous zinc chloride can be made from the reaction of the metal with chlorine or hydrogen chloride. It is usually made commercially by the reaction of aqueous hydrochloric acid with scrap zinc materials or roasted ore, ie, cmde zinc oxide. The solution is purified in various ways depending upon the impurities present. For example, iron and manganese precipitate after partial neutralization with zinc oxide or other alkah and oxidation with chlorine or sodium hypochlorite. Heavy metals are removed with zinc powder. The solution is concentrated by boiling, and hydrochloric acid is added to prevent the formation of basic chlorides. Zinc chloride is usually sold as a 47.4 wt % (sp gr 1.53) solution, but is also produced in soHd form by further evaporation until, upon cooling, an almost anhydrous salt crystallizes. The soHd is sometimes sold in fused form. 

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