Metals and Minerals
There are thought to be well over 4,000 different minerals, many of which contain metallic elements.
Minerals are solid, naturally occurring inorganic substances found in the Earth’s crust. They have a unique chemical composition and crystal structure.
Metals are elementary substances, such as gold, silver and copper. They are crystalline when solid and naturally occur in minerals. They are often good conductors of electricity and heat, shiny and malleable. The metals we use day-to-day are converted from metallic ores to their final form. This usually requires the use of chemicals and special technology.
Common Groups of Metals
Metals are often grouped by their properties or function.
- Precious metals: This includes gold, silver, platinum and diamonds. About 90 per cent of the total gold production comes from gold mines. The remaining 10 per cent is produced as a by-product from mining other metals, such as copper and nickel. Precious metals are traded on world markets and used in a range of applications from jewellery to electronics to catalytic converters in cars.
- Base metals: This mainly means copper, lead and zinc, which have a lower value. Refined forms of these metals are commonly traded on world markets. These are the basic building materials for much of the world around us.
- Ferrous metals: Those with a high iron content, which includes all types of steel. Chromium, cobalt, manganese and molybdenum are commonly included in this group because their major use is to improve the properties of steel.
- Non-ferrous metals: This includes aluminium, copper, lead, magnesium, nickel, tin and zinc, since they have principal uses unrelated to steelmaking. Note that there is some overlap with the base metals group – the choice of the group depends on the context.
- Rare earth metals: These are not actually all that rare but their extraction is complex and difficult. They include scandium, yttrium, lanthanum and the 14 elements (lanthanides) following lanthanum in the periodic table. They have widespread uses, though in small volume, in the manufacturing of glass, ceramics, glazes, magnets, lasers and television tubes, as well as in refining petroleum.
- Alloys: These are made by mixing two or more metallic elements to form a new, unique substance that has differing chemical and physical properties to its component parts. Over 90 per cent of the metals in use today are alloys.
Alloying elements are usually added to pure metals to enhance their strength or improve properties, such as corrosion resistance, wear resistance and ability to be cut. Demanding industrial requirements, such as extreme temperature resistance, strength for high-pressure applications, fatigue resistance, weight reduction or toughness, often in combination, have led to the development of a wide range of alloys.
The most common alloys are broadly classified as steels. These characteristically strong alloys, formed from iron and carbon, can be mixed with other elements to further improve performance and durability. For example, a car contains more than 10 different steel alloys for body parts, gears, drive trains, crankshafts, valves and so on.
Experts predict that the need for more energy efficient systems, information technology and space exploration will be major driving forces for the development of new alloys.
Assessing Product Hazards
Metals and minerals will only have a hazardous impact under certain conditions (known as the route of exposure). For example, solder fumes are highly toxic if they are inhaled but perfectly safe if they encounter skin. A chemical’s hazard classification is based on inherent hazards. It doesn’t consider normal conditions of use where there are no realistic circumstances in which exposure could cause harm. Industry has argued for many years that this needs to be addressed.
The way metals and minerals are classified has a direct impact on how and where they can be used as classification forms the basis for other regulatory controls.
Compliance with the UNECE Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is a legal requirement in a growing number of countries. Where implemented, the GHS provides a standardised, modern and universal format for conveying hazard information to users through the provision of safety data sheets and hazardous products labels. Operators in downstream sectors need access to up-to-date information so that they can ensure that the safety of their workers, sites, customers and the environment is maintained.
How ICMM is Improving Performance
ICMM company members commit to assess the hazards of mining products according to the GHS (or equivalent relevant regulatory systems) and to communicate through safety data sheets and labelling as appropriate.
ICMM members are also working towards the development of metals-focused testing methodologies to ensure that the hazard profiles of metals and minerals can be assessed accurately. The information generated enables metals and minerals to be used effectively and safely.
Implications of a Hazardous Classification
- Transportation: In terms of transportation, the most important classifications are those that qualify physio-chemical properties such as flammability, explosivity and corrosivity to other metals. For example, mercury is corrosive to aluminium, so it is banned on planes. The hazard classification determines how the product can be transported safely (eg with packaged goods it defines what drums can be used). The lack of suitable packaging can stop products being transported to customers or other sites and so has major implications on trade. Different transport modes can have different criteria, eg sea transport is defined by the International Maritime Organization (IMO).
- Worker health and safety protection measures: Classification acts as a trigger for health protection measures for workers on site and throughout the supply chain. For example, if a product is classified as presenting an inhalation hazard, measures to control exposure such as air extraction and respiratory protection may need to be implemented.
- Manufacturing site safety: Classification is a key criterion used to define implementation measures to ensure a site is operating safely. For example, in the EU the Seveso Directive defines the level of controls necessary based on stocks of products of a specific classification held on site.
- Downstream uses: Classification can be a defining criterion in some legislation to allow a chemical (including a metal or metal compound) to be used in everyday products (eg cosmetics, toys, food packaging and textiles) as well as in professional ones.