Copper, and Iron

Recall that oxides in wNch the metal has a hi oxidation manber are covalent and addc, whereas those in wNch the metal has a low oxidation nianber are ionic and basic (see Section 15.11). 

The preparation of iron in a blast furnace and sleelmaking were discussed in Section 20.2. Pure iron is a gray metal and is not particularly hard. It is an essential element in living systems. 

Iron reacts with hydrochloric acid to give hydrogen gas  

Concentrated sulfuric acid oxidizes the metal to Fe, but concentrated nitric acid renders the metal passive by forming a thin layer of Fe304 over the surface. One of the best-known reactions of iron is rust formation (see Section 19.7). The two 

Impure copper can be purified by electrolysis (see Section 20.2). After silver, which is too expensive for large-scale use, copper has the highest electrical conductivity. It is also a good thermal conductor. Copper is used in alloys, electrical cables, plumbing (pipes), and coins. 

The presence of compounds of iron and copper can cause fibre damage during bleaching, by so-called catalytic tendering . It is important to know if such contaminants are present and remove them prior to bleaching. 

0 g fibre is spotted with 1-2 drops of nitric acid (5%) and allowed to stand for 2-3 min so that any iron present is oxidised to ferric ions. Then 2-4 drops of potassium thiocyanate solution (10%) are added and a red colour indicates ferric ions. The intensity of colour indicates the amount. The test can be carried out on an ashed sample. 

In another method, the fibre is spotted with hydrochloric acid (10%) and the acidified area is spotted with 1 % potassium ferrocyanide. A dark blue colour indicates the presence of iron. 

For testing of copper, the ash is spotted with 5-10 drops of nitric acid (10%) and then dilute ammonia (1 1) is added until the ash is alkaline. A blue colour shows the presence of copper. For fabric, the sample is first spotted with dilute nitric acid and then after neutralisation with ammonia, 1-2 drops of diethyldithiocarbamate solution (0.1 %) are spotted on to the same area. A yellow colour shows the presence of copper. 

Metal contents may also be determined on the ash by emission spectroscopy or atomic absorption spectroscopy. 

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For organometailic compounds, the situation becomes even more complicated because the presence of elements such as platinum, iron, and copper introduces more complex isotopic patterns. In a very general sense, for inorganic chemistry, as atomic number increases, the number of isotopes occurring naturally for any one element can increase considerably. An element of small atomic number, lithium, has only two natural isotopes, but tin has ten, xenon has nine, and mercury has seven isotopes. This general phenomenon should be approached with caution because, for example, yttrium of atomic mass 89 is monoisotopic, and iridium has just two natural isotopes at masses 191 and 193. Nevertheless, the occurrence and variation in patterns of multi-isotopic elements often make their mass spectrometric identification easy, as depicted for the cases of dimethylmercury and dimethylplatinum in Figure 47.4. 

The copper-chelating abihty of sahcylaldoxime has been used to remove copper from brine in a seawater desalination plant effluent. A carbon—sorbate bed produced by sorption of the oxime on carbon proved to be extremely effective in the continuous process (99). In another apphcation, the chelating abihty of sahcylaldoxime with iron and copper was used to stabilize bleaching powders containing inorganic peroxide salts (100). 

Fig. 10. Stmctural P/M parts made from iron- and copper-based powders. Other P/M parts can be made from a range of materials. See text.

The treatments used to recover nickel from its sulfide and lateritic ores differ considerably because of the differing physical characteristics of the two ore types. The sulfide ores, in which the nickel, iron, and copper occur in a physical mixture as distinct minerals, are amenable to initial concentration by mechanical methods, eg, flotation (qv) and magnetic separation (see SEPARATION,MAGNETIC). The lateritic ores are not susceptible to these physical processes of beneficiation, and chemical means must be used to extract the nickel. The nickel concentration processes that have been developed are not as effective for the lateritic ores as for the sulfide ores (see also Metallurgy, extractive Minerals recovery and processing). 

Benzene Oxychlorin tion. In the benzene oxychlorination process, also known as the Raschig Hooker process, benzene is oxychlorinated with hydrogen chloride, air, and with the presence of iron and copper chloride catalyst to form chlorobenzene. The reaction occurs at 200—260°C and atmospheric pressure. The chlorobenzene is hydrolyzed at 480°C in the presence of a suitable catalyst to produce phenol and chloride. The yield of phenol is - 90 mol% of theoretical. These plants have been shut down for environmental and economic reasons. 

Polyunsaturated fatty acids in vegetable oils, particularly finolenic esters in soybean oil, are especially sensitive to oxidation. Even a slight degree of oxidation, commonly referred to as flavor reversion, results in undesirable flavors, eg, beany, grassy, painty, or fishy. Oxidation is controlled by the exclusion of metal contaminants, eg, iron and copper addition of metal inactivators such as citric acid minimum exposure to air, protection from light, and selective hydrogenation to decrease the finolenate content to ca 3% (74). Careful quality control is essential for the production of acceptable edible soybean oil products (75). 

Textiles. Sorbitol sequesters iron and copper ions in strongly alkaline textile bleaching or scouring solutions (see Textiles). In compositions for conferring permanent wash-and-wear properties on cotton fabrics, sorbitol is a scavenger for unreacted formaldehyde (252) and a plasticizer in sod-resistant and sod-release finishes (253). 

Condensate Polishing. Ion exchange can be used to purify or poHsh returned condensate, removing corrosion products that could cause harmful deposits in boilers. Typically, the contaminants in the condensate system are particulate iron and copper. Low levels of other contaminants may enter the system through condenser and pump seal leaks or carryover of boiler water into the steam. Condensate poHshers filter out the particulates and remove soluble contaminants by ion exchange. 

Sa.tura.tion Index. Materials of constmction used in pools are subject to the corrosive effects of water, eg, iron and copper equipment can corrode whereas concrete and plaster can undergo dissolution, ie, etching. The corrosion rate of metallic surfaces has been shown to be a function of the concentrations of Cl ,, dissolved O2, alkalinity, and Ca hardness as well as buffer intensity, time, and the calcium carbonate saturation index (35). 

Thus, roasting is avoided. The process, especially amenable to high iron and copper concentrates, has been installed by Cominco, Ltd. (44) at Trad, B.C., Canada, and will be installed at the Kidd Creek Mines, Ltd., plant at Timmins, Ontario. 

For many centuries the application of materials for low friction and wear in sliding and rolling contacts primarily involved wood, stone, leather, iron, and copper. Almost all engineering materials have since been employed at one time or another in the continuing search for the best bearing material. Final selection is commonly a judgment based on the most essential material properties, ease of appHcation, and cost. 

Total carbon in beryUium is determined by combustion of the sample, along with an accelerator mixture of tin, iron, and copper, in a stream of oxygen (15,16). The evolved carbon dioxide is usuaUy measured by infrared absorption spectrometry. BeryUium carbide can be determined without interference from graphitic carbon by dissolution of the sample in a strong base. BeryUium carbide is converted to methane, which can be determined directly by gas chromatography. Alternatively, the evolved methane can be oxidized to carbon dioxide, which is determined gravimetricaUy (16). 

Nonfibrous Reinforcements. Because of the higher costs associated with nonasbestos fibers and the performance requirements needed in replacing asbestos, platy minerals such as mica and talc, and metal powders such as iron and copper, are being used as a portion of the total reinforcement package in NAOs. 

The addition of oxides to ceramic bodies and to glasses to produce color has been known since antiquity (2). The use of iron and copper oxides predates recorded history. Cobalt was introduced into Chinese porcelain about 700 AD. Chromium compounds have been used since 1800 AD. 

The electrolytes used were acetate buffer at pEI values 2, 4 and 6 and the same electrolyte is used in the presence of EDTA at pEI values of 2 and 6. Iron and copper contents could be most easily determined in EDTA medium at pH 6. The best medium for nickel was found to be as ammonia buffer pH 9.5 qg/L, it could be separated from zinc in this medium. The elements determined in white and red wine were Cu, Pb, Zn, Cd, Fe and Ni. The quantities found were for iron about 9000 qg/L, for copper 290 qg/L, Ni 80 qg/L, lead 150 qg/L and zinc 460 qg/L. The validation was made by determining each element under different conditions. 

Similarly, graphitically corroded cast iron (see Chap. 17) can assume a potential approximately equivalent to graphite, thus inducing galvanic corrosion of components of steel, uncorroded cast iron, and copper-based alloys. Hence, special precautions must be exercised when dealing with graphitically corroded pump impellers and pump casings (see Cautions in Chap. 17). 

The difference in stability between FeO and NiO is not as large as that between iron and copper oxides, and so the preferential oxidation of iron is not so marked in pentlandite. Furthermore, the nickel and iron monoxides form a continuous series of solid solutions, and so a small amount of nickel is always removed into die oxide phase (Table 9.2). 

Shell moulding - Steel, iron and copper alloys... 

GRAVITY DIE CASTING PROCESS CAPABILITY MAP FOR IRON AND COPPER AND ZINC ALLOYS... 

Unalloyed nickel is used where it is necessary to eliminate iron and copper contamination (nickel 200 up to 300°C and nickel 201 above SOO C). 

In 1955 it was discovered that mixtures of ammonium nitrate and fine coal dust have satisfactory blasting capabilities in large (9 inch) holes used in open-pit coal mines to remove the rock and soil covering the coal. Polyethylene bags containing this material deform to fit the hole and provide moderate water resistance. ANFO is used in open-pit iron and copper mines and for construction such as road building. The mixture is air blown into 2-inch holes or less m maiiv underground mines. 

For these reasons alloying elements appear in all the commercial anodes, and very careful quality control is required to keep disadvantageous tramp elements (notably iron and copper) below defined threshold levels. Many anode failures can be attributed to poor production quality control. A guide to minimum quality standards has been produced ... 

Alloying additions are made to improve the performance of an anode material. Of equal importance is the control of the levels of impurity in the final anode, since impurities (notably iron and copper) can adversely affect anode performance. Thus careful quality control of the raw materials used and the manufacturing process adopted is essential to sound anode production. This too is discussed below. 

Both iron- and copper-based alloys are corroded more easily on either side of the neutral pH band. In low pH conditions e.g. due to carbon dioxide, the acidic environments attack the alloys readily, causing damage both at the points of initial corrosion and perhaps, consequentially, further along the system, by screening the surface with corrosion products and permitting the development of differential aeration cells. 

The presence of tin and of considerable quantities of iron and copper interfere with the determinations. 

Wurtz s point about cobalt and nickel is well taken given that classification was by atomic weight there would have been no basis for the prediction of two elements between iron and copper, had neither cobalt or nickel been known, and no basis for predicting the existence of the other had only one of them been known. 

Effect of Certain Oxides of Iron and Copper on the Properties of TNT , PATR 1597 (1946) 13) W.M. Latimer I.H. Hildebrand, Reference Book of Inorganic Chemistry , MacMillan, NY (1947) 14) A.J. Clear, Stability of Propel-... 

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