Nickel metal dusting

J. Zhang and D. J. Young, Kinetics and Mechanisms of Nickel Metal Dusting 1. Kinetics and Morphology, Corrosion Science, 49 1496-1512(2007). 

Binary nickel-copper alloys have already been investigated as substitutes for nickel catalysts in order to reduce the amount of coking because of the noncatalytic nature of copper [15-18], Nickel-copper alloys, however, have never been tested for their resistance to metal dusting. The aim of this work was to study the effects of adding copper on the behaviour of nickel metal dusting and associated coking. 

Zhang J, Young D J, Kinetics and mechanisms of nickel metal dusting. I. Kinetics and morphology . Corrosion Science, 2007 49 1496-1512... 

Exposure to nickel metal and soluble compounds (as Ni) should not exceed 0.05 mg/cms (8-hour time-weighted average - 40-hour work week). Nickel sulfide fume and dust is recognized as being potentially carcinogenic. 

Metal dusting usually occurs in high carbon activity environments combined with a low oxygen partial pressure where carburisation and graphi-tisation occur. Usually pits develop which contain a mixture of carbon, carbides, oxide and metal (Fig. 7.52). Hochmann" proposed that dusting occurs as the result of metastable carbide formation in the high carbon activity gas mixture which subsequently breaks down into metal plus free carbon. The dependence of the corrosion resistance of these nickel alloys on the protective oxide him has been described accelerated or internal oxidation occurs only under conditions that either prevent the formation, or lead to the disruption, of this him. In many petrochemical applications the pO is too low to permit chromia formation (ethylene furnaces for example) so that additions of silicon" or aluminium are commonly made to alloys to improve carburisation resistance (Fig. 7.53). 

C. M. Chun, G. Bhargava and T. A. Ramanarayanan, Metal Dusting Corrosion of Nickel Based Alloys,/. Electrochem. Soc., 154 C231-C240(2007). 

Z. Zeng and K. Natesan, Relationship of Carbon Crystallization to the Metal-dusting Mechanism of Nickel, Chem. Mater., 15 872-878 (2003). 

You may be exposed to higher levels of nickel if you work in industries that process or use nickel. You may be exposed to nickel by breathing dust or fumes (as from welding) or by skin contact with nickel-containing metal and dust or solutions containing dissolved nickel compounds. A national survey conducted from 1980 to 1983 estimated that 727,240 workers are potentially exposed to nickel metal, nickel alloys, or nickel compounds. 

Department of Health and Human Services (DHHS) has determined that nickel and certain nickel compounds may reasonably be anticipated to be carcinogens. The International Agency for Research on Cancer (lARC) has determined that some nickel compounds are carcinogenic to humans and that metallic nickel may possibly be carcinogenic to humans. The EPA has determined that nickel refinery dust and nickel subsulfide are human carcinogens. 

Occupational exposure to nickel may occur by dermal contact or by inhalation of aerosols, dusts, fumes, or mists containing nickel. Dermal contact may also occur with nickel solutions, such as those used in electroplating, nickel salts, and nickel metal or alloys. Nickel-containing dust may be ingested where poor work practices exist or poor personal hygiene is practiced. A National Occupational Exposure Survey (NOES) conducted by NIOSH from 1981 to 1983 estimates that 727,240 workers are potentially exposed to some form of nickel metal, alloys, salts, or inorganic nickel compounds in the United States (NIOSH 1990). The form of nickel these workers were probably exposed to and the level of exposure for different industries and operations were reviewed by Warner (1984) and lARC (1990). 

Nickel metal, nickel monoxide and sulfide dust, soluble nickel compounds Nickel carbonyl Germany nickel carbonyl Sweden nickel metal... 

HYDROXIDE (7783-06-4) HjS A highly flammable, toxic, and reactive gas [explosion limits in air (vol %) 4.3 to 45.5 Flash point -116°F/-82°C autoignition temp 500°F/260°C Fire Rating 4]. Violent reaction with strong oxidizers, metal oxides (especially those of chromium, iron, lead, mercury, nickel, and zinc), metal dusts and powders, bromine pentafluoride, chlorine trifluoride, chromimn trioxide, chromyl... 

HUMAN TOXICITY DATA There is inadequate evidence in humans for the carcinogenicity of metallic nickel and nickel alloys nickel compounds are carcinogenic to humans (Group I) metallic nickel is possibly carcinogenic to humans (Group 2B) EPA inhalation unit nsk estimates of 2.4 x 10 pg/m for nickel refiner dusts and 4.8 x lO" pg/m for nickel subsulfide EPA classifies nickel refiner dust and nickel subsulfide as Group A, human carcinogens. 

Substances which ignite spontaneously in air are also classified as highly flammable. Well-known examples are the alkali metals, many organometallic compounds, e. g., methyl lithium, dimethyl stannous, and many silanes or very fine metal dusts, e.g., Raney nickel, reduced ferrous compounds, and aluminum, which behave pyrophorically. 

Metal workers are exposed to numerous exogenous factors that play a substantial role in tbe development of allergic as well as irritant contact dermatitis (ICD). Even though nickel is regarded as the most frequent source of all reported metal allergies [i], metal-work fluids (MWFs) are the most important cause of irritant hand dermatitis. Other factors such as metal dust, friction, pressure, heat and humidity also contribute to the irritation of the skin [2]. However, the metal industry is a wide fleld, and exposure may vary widely depending on the kind of job and the type of metal industry. 

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