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 (Nickel Institute, 2008). 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 sub- sulfide (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 (Nickel Institute, 2008).

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 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 2-1:  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 2-2:  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

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). Traditionally the sulfidic ores have dominated but that is shifting and future primary nickel production will be more dependent on lateritic ores. It is important to note, however, that secondary sources of nickel – overwhelmingly in the form of scrap stainless steels and nickel alloys but also including spend catalysts, batteries and other products – will constitute a large and ever increasing percentage of world nickel supply.

With the 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.

The primary nickel industry is growing and evolving. There are a number of new entrants and a number of established producers are now part of some of the largest mining companies in the world. Smelting or refining operations take place in more than a dozen countries and are fed with concentrates from many more. The volumes in domestic and international trade are increasing, as are the ways in which the intermediate and finished products are packaged and transported.