SAFE USE OF NICKEL IN THE WORKPLACE
Last Revised: 7/2002
2.1 NICKEL-PRODUCING INDUSTRIES
2.2 NICKEL-USING INDUSTRIES
2.3 REFERENCES
Apart from unusual sources, such as massive nickel in meteorites, nickel from natural sources is usually found at modest concentrations and occurs in conjunction with a wide variety of other metals and non-metals. Although nickel is a ubiquitous metal in the natural environment, industrialization has resulted in increased concentrations of nickel in both rural and urban environments.
Nickel-bearing particles are present in the atmosphere as constituents of suspended particulate matter and, occasionally, of mist aerosols. The primary anthropogenic stationary source categories that emit nickel into ambient air are: (1) combustion and incineration sources (heavy residual oil and coal burning units in utility, industrial, and residential use sectors, and municipal and sewage sludge incinerators), (2) high temperature metallurgical operations (steel and nickel alloy manufacturing, secondary metals smelting, and co-product nickel recovery), (3) primary production operations (mining, milling, smelting, and refining), and (4) chemical and catalyst sources (nickel chemical manufacturing, electroplating, nickel-cadmium battery manufacturing, and catalyst production, use, and reclamation). Typical ambient air concentrations of nickel range from 6 to 25 ng Ni/m3 (Tsalev and Zapriano, 1984; Sunderman, 1988).
In aquatic systems, such as in ambient or drinking water, nickel is usually present as the nickel cation (Ni2 ), together with other anions such as hydroxyl (OH-), sulfate (SO42-), chloride (Cl-), carbonate (CO32-), or nitrate (NO3-). Sources of nickel in ambient waters include chemical and physical degradation of rocks and soils, deposition of atmospheric nickel-containing particulate matter, and discharges from industrial processes. In unpolluted water supplies, a range of 1 to 50 µg Ni/l has been reported (Stoeppler, 1980). Nickel levels in soil vary between 5 and 500 µg Ni/g depending on geological factors.
For purposes of this document, however, the main concern is nickel presence in occupational settings. It is evident that industrial processes present potential for exposure of workers to higher concentrations of nickel and/or its compounds than those generally found in the natural environment. Occasionally, these exposures may be to a refined form of nickel, but usually they are mixed, containing several nickel compounds and/or contaminants. These "mixed exposures" often complicate the interpretation of health effects of specific nickel species.
2.1 NICKEL-PRODUCING INDUSTRIES
Workers engaged in nickel production—which may include mining, milling, concentrating, smelting, converting, hydrometallurgical processes, refining, and other operations—are exposed to a variety of nickel minerals and compounds depending upon the type of ore mined and the process used to produce intermediate and primary nickel products (NiDI, 1996). These production processes are often broadly grouped under the industry sectors of mining, milling, smelting, and refining.
Generally, exposures in the producing industry are to moderately soluble and insoluble forms of ores and nickel, such as pentlandite (Ni,Fe)9S8, nickeliferous pyrrhotite, (Fe,Ni)1-xS, nickel subsulfide (Ni3S2), silicates (including garnierite and smelting slags), and oxidic nickel (including nickeliferous limonite, NiO, Ni-Cu oxides, and complex oxides with other metals such as iron and cobalt). Exposures to metallic and soluble nickel compounds are less common. Soluble nickel compounds are more likely to be found in hydrometallurgical operations, such as leaching and electrowinning, than in mining and smelting operations (NiDI, 1996).
Primary nickel products produced from the above operations are often characterized as Class I and II. Class I products are pure nickel metal, defined as containing 99.8% Ni (Table 1). Class II products have <99.8% Ni and encompass three different types of products: metallic nickel in various product forms, nickel oxides, and ferronickels (Table 2).
Class I products are marketed in a variety of forms including pure electrolytic full-plates, nickel squares, rounds, or crowns, spherical pellets, briquettes of consolidated pure nickel powder compacts, and several different pure nickel powders. The metallic nickels in Class II are electrolytic nickel products and briquettes containing >99.7% Ni, but <99.8% Ni and utility nickel shot containing >98.7% Ni. The oxide products in Class II include rondelles-partially reduced nickel oxide compacts containing about 90% Ni-and compacts of nickel oxide sinter containing approximately 75% Ni. The ferronickel products contain about 20% to 50% Ni.
TABLE 1: CLASS I PRIMARY NICKEL PRODUCTS, 99.8 PERCENT NICKEL OR MORE
| Product Name | Nickel Content, Wt% | Form | Principal Impurity |
| Electro - electrolytic nickel squares, rounds, crowns | 99.8 - 99.99 | Massive | Various |
| Pellets - from nickel carbonyl | > 99.97 | Massive | Carbon |
| Briquettes - metallized powder compacts | >99.8 | Massive (possibility of some powder formation during transport and handling) | Cobalt |
| Powders - by carbonyl decomposition or by precipitation | >99.8 | Dispersible | Carbon |
TABLE 2: CLASS II PRIMARY NICKEL PRODUCTS, LESS THAN 99.8 PERCENT NICKEL
| Product Name | Nickel Content, Wt% | Form | Principal Impurity |
| Electro | > 99.7 | Massive | Cobalt |
| Briquettes | > 99.7 | Massive (possibility of some powder formation during transport and handling) | Cobalt |
| Utility - shot | > 98.7 | Massive | Iron |
| Sinter - nickel oxide and partially metallized | ~75 - 90 | Massive (possibility of some powder formation during transport and handling) | Oxygen |
| Ferronickel - ingots, cones, shot, granules | ~20 - 50 | Massive | Iron |
With the obvious exception of inhalable nickel powders, all the above products are massive and cannot be inhaled. However, in some instances, inhalable particles may be generated as a result of the degradation of briquettes, rondelles, and sinters during production, handling, packaging, shipping, unpacking, or subsequent treating or processing of these products.
There are about 2 dozen producers of primary nickel in the world, with smelting or refining operations in more than a dozen countries. While the processes of each of these producers differ, they may be broadly classified into two groups: (1) those in which nickel is recovered from sulfidic ores (generally, but not always, found in the temperate zones of the earth's crust) and (2) those which are recovered from lateritic ores (commonly present in areas that currently are, or geologically were, tropical and semi-tropical areas).
The nickel industry gathers and records statistics regarding the use of primary nickel according to six sectors. The approximate average 1996 world proportional consumption of each of these sectors is shown in Figure 1 (NiDI, 1996).
| FIGURE 1 DISTRIBUTION OF PRIMARY NICKEL, 1996  Source: NiDI, 1996 |
Figure 1 indicates that nearly 90 percent of all nickel is consumed in the production of different stainless and alloy steels, other nickel alloys (of which there are thousands) and foundry products. About nine percent is used in plated products, and the remaining two percent is used in a number of "other" relatively small applications, including chemicals, catalysts, batteries, coins, pigments, and powders (including powder metallurgy).
Most of the plating, foundry and "other" applications are "end-uses" of nickel; that is to say, the products are used directly by the customer or "end-user." The steels and other nickel alloys, on the other hand, are "intermediate" products that must be further processed or "transformed" into end-use commercial products in a number of industrial applications. These applications include building and construction materials; chemicals production; process equipment; petroleum refining, power generation, and other industrial processes components and machinery; automotive, railway, marine, aerospace, and other transportation equipment; electronics; and consumer and other products (Figure 2).
| FIGURE 2 END USES OF PRIMARY NICKEL, 1996  Source: NiDI, 1996 |
Many process operations are common to the production of stainless steels, alloy steels, high nickel alloys, and their subsequent transformations into commercial and consumer products. Thus, for the sake of simplicity, it is practical to consider these operations as a group, including foundry applications.
With respect to the remaining two percent of "other" small uses, the number of processes attending these uses is considerably greater than the number of use sectors themselves. For example, there are numerous processes for making coins, batteries, chemicals, and catalysts. Furthermore, the presence of finely divided materials as feedstocks, process intermediates, or products within these sectors has resulted in the design of equipment and procedures to control airborne particulates and workplace exposures at lower levels than might otherwise prevail.
[Further information on the production and use of nickel can be obtained from the Nickel Development Institute (NiDI) at http://www.nidi.org]
NiDI. Nickel Development Institute. (1996). Internal analysis tables. Nickel Development Institute.
Sunderman, F. W., Jr. (1988). Biological activities of nickel oxides; Final Report of Phases II and IV. Durham, NC: Nickel Producers Environmental Research Association, NiPERA Contract No. 87-08.
Stoeppler, M. (1980), Analysis of nickel in biological materials and natural waters. In: Nriagu, J. O., ed Nickel in the environment. New York, NY: John Wiley & Sons, 661-821.
Tsalev, D. L., Zaprianov, Z. K. (1984). Atomic absorption spectrometry in occupational and environmental health practice, v. 1. Boca Raton, FL: CRC Press.
