Nickel concentration method

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). 

The observed ratio aaiioy/aNi agreed well with the Ni content predicted.) As discussed later, it was believed that hydrogen chemisorption was proportional to the surface nickel concentration (see Section IV). It is clear, however, that chemisorption as a method of surface area measurement must be used with discretion in the case of alloy films. 

Methods for Determining Biomarkers of Exposure and Effect. Nickel concentrations in hair, nails, blood, or urine are elevated in exposed individuals. A correlation has been established between nickel levels in urine, plasma, and feces in occupationally exposed workers and nickel levels in air (Angerer and Lehnert 1990 Bemacki et al. 1978 Hassler et al. 1983). If the identity of the nickel compounds to which workers are exposed is known, nickel levels in urine and plasma can be used as a biomarker for nickel exposure (Sunderman 1993). Available analytical methods can determine the nickel levels in these media in both unexposed and occupationally exposed persons. Methods to determine nickel speciation in biological media require further development. 

Lowering the electrolyte resistance by varying its composition does not offer many possibilities to work with. The concentration of copper and temperature must be in the usual range to get a good quality deposit. Increasing the concentration of sulfuric acid will increase the chemical dissolution of the anode. The most important method to improve electrolyte conductivity is often by limiting the nickel concentration. 

Another technique we used to observe these distributions is scanning electron microscopy with energy dispersive x-ray analysis (EDAX). Concentrations of Cyasorb UV 1084, [2-2 -thiobis(4-ter -octylphenolato)-n-butylamine nickel], a nickel-containing UV absorber, were point counted to obtain nickel concentrations along a spherulite diameter. Figure 3 shows results for 1 and 4 wt % additive. This shows a uniform melt concentration, a boundary peak, a lower concentration within the spherulite, and a central dip. The resolution and sensitivity with this technique are poorer than with the optical microscopy. With every method, thin film crystallized samples and microtomed sections of bulk samples gave similar results. 

Analytical Methods and Speclatlon Electrothermal atomic absorption spectrophotometry (ETAAS), differential pulse adsorption voltammetry (DPAV), isotope-dilution mass spectrometry (ID-MS), and inductively coupled plasma mass spectrometry (ICP-MS) furnish the requisite sensitivity for measurements of nickel concentrations in biological, technical and environmental samples (Aggarwal et al. 1989, Case et al. 2001, Stoeppler and Ostapczuk 1992, Templeton 1994, Todorovska et al. 2002, Vaughan and Templeton 1990, Welz and Sperling 1999). The detection limits for nickel determinations by ETAAS analysis with Zeeman background correction are approximately 0.45 jg for urine,... 

Comparison of catalytic activities for samples containing different percentages of nickel was done by the method which had previously proved convenient for testing the dehydrocydization of n-heptane over chromia-alumina. In all activity tests the total nickel concentration was set at 3.33 per cent nickel. In all but the most dilute sample this was achieved by making a mechanical dilution of the original prepared catalyst. The diluting i ent was y-alumina identical with that used for impregnation. 

Next we applied this assay to the assessment of a nickel-titanium alloy [18]. We selected MOLT-3 that was the most sensitive against nickel ion (see Fig. 11). Nickel-titanium (NiTi) alloys were made by an arc melting method. Those alloys varied greatly in composition (Table 3) and phase (Fig. 12). First these alloys were sterilized by soaking them in 70 % ethanol solution. Then they were immersed in phosphate buffer and incubated at 36.5 °C for 25 h. We collected the extract and added it to a MOLT-3 culture plate (the ratio of extract to supernatant was 1 1). After a 4-day culture, we measured the viable cell number of each culture condition. The order of the viable cell numbers was coupon 5> coupon 2> coupon 1, coupon 3> coupon 4 (Fig. 13). We also measured the nickel concentration of the extract by atomic absorptirai spectrophotometry. The order of the nickel concentration was coupon 4> coupon 1, coupon 3> coupon 2> coupon 5 (Table 4), which was... 

The extractive concentration method described for the element silver using hexamethylene ammonium hexamethylene dithiocarbamate (HMDC) may also be used for nickel. 

A DME has also been used for the amperometric determination of oxygen in river water and effluent samples. This involves the application of a constant potential of —1.5V versus the SCE. This approach has been found to be useful in eliminating interferences from cyanide and sulfide, as well as correcting for contributions from metal ions, such as iron, copper, zinc, and nickel. The method can be reliably used for oxygen determination when present within the concentration range of 0-15 mg 1 . ... 

Typically, pressure filtration will reduce copper and nickel concentrations below or close to the limits of detection, respectively, about 5 and 10 i.gL . Residual iron normally is 0.2-0.3 ppm [66]. Final disposal of the solids can be by one of the methods... 

The determination of nickel in blood or plasma/serum is used for the biological monitoring of occupationally exposed persons and for the surveillance of subjects with potential iatrogenic sources of exposure to nickel such as dialysis treatment, leaching of nickel from nickel-containing alloys as prostheses and implants, and contaminated intravenous medications [2,22,61]. Contamination of the blood specimens from the needles for venipuncture has been reported. But recent experiences show that after using stainless steel cannulas with the common analytical methods an increase of the nickel concentration in blood could not be detected. 

It is good practice to keep concentrations of airborne nickel in any chemical form as low as possible and certainly below the relevant standard. Local exhaust ventilation is the preferred method, particularly for powders, but personal respirator protection may be employed where necessary. In the United States, the Occupational Safety and Health Administration (OSHA) personal exposure limit (PEL) for all forms of nickel except nickel carbonyl is 1 mg/m. The ACGIH TLVs are respectively 1 mg/m for Ni metal, insoluble compounds, and fume and dust from nickel sulfide roasting, and 0.1 mg/m for soluble nickel compounds. The ACGIH is considering whether to lower the TLVs for all forms of nickel to 0.05 mg/m, based on nonmalignant respiratory effects in experimental animals. 

Analysis of zinc solutions at the purification stage before electrolysis is critical and several metals present in low concentrations are monitored carefully. Methods vary from plant to plant but are highly specific and usually capable of detecting 0.1 ppm or less. Colorimetric process-control methods are used for cobalt, antimony, and germanium, turbidimetric methods for cadmium and copper. Alternatively, cadmium, cobalt, and copper are determined polarographicaHy, arsenic and antimony by a modified Gutzeit test, and nickel with a dimethylglyoxime spot test. 

Electrochemistry and Kinetics. The electrochemistry of the nickel—iron battery and the crystal stmctures of the active materials depends on the method of preparation of the material, degree of discharge, the age (Life cycle), concentration of electrolyte, and type and degree of additives, particularly the presence of lithium and cobalt. A simplified equation representing the charge—discharge cycle can be given as ... 

A similar process has been devised by the U.S. Bureau of Mines (8) for extraction of nickel and cobalt from United States laterites. The reduction temperature is lowered to 525°C and the hoi ding time for the reaction is 15 minutes. An ammoniacal leach is also employed, but oxidation is controlled, resulting in high extraction of nickel and cobalt into solution. Mixers and settlers are added to separate and concentrate the metals in solution. Organic strippers are used to selectively remove the metals from the solution. The metals are then removed from the strippers. In the case of cobalt, spent cobalt electrolyte is used to separate the metal-containing solution and the stripper. MetaUic cobalt is then recovered by electrolysis from the solution. Using this method, 92.7 wt % nickel and 91.4 wt % cobalt have been economically extracted from domestic laterites containing 0.73 wt % nickel and 0.2 wt % cobalt (8). 

The molybdenum, tungsten and tantalum concentration influence on LCD nickel-ferrous HRS resistance, used for gas turbine installations parts is investigated. The tests were carried out on modeling compositions. Samples were molded on the basis of an alloy of the ZMI-3C. The concentration of tantalum varied from 0 up to 5% with a step of 0,5%. The contents of elements were determined by a spectral method. 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

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