Main uses and applications

The primary commercial source of phosphorus is phosphorite, commonly referred to as phosphate rock, with significant quantities also derived from vivianite and wavellite. Phosphorus occurs as one of three allotropes i.e., different physical forms of phosphorus molecules: white, red, and black phosphorus, although their true colours do not exactly reflect this nomenclature. White phosphorus (sometimes referred to as yellow phosphorus) is a result of industrial manufacturing, which is spontaneously flammable when exposed to air at temperatures of 35° C (95 °F) and highly toxic. While it is not considered a chemical weapon, when used against civilian populations, white phosphorus violates the Convention on Certain Conventional Weapons.

Red phosphorus, meanwhile ranges from orange to purple in colour and is created by heating the white form of phosphorus to temperatures around 200-250 °C (390-480 °F). Black phosphorus is made under pressure, resembles graphite, and has a high electrical conductivity.

Phosphorus is utilised in a wide range of applications. Concentrated phosphoric acids can be used to manufacture fertilisers, with 95% of the phosphate rock mined in the United States used to make either fertiliser or food supplements for animals. It is also an essential macronutrient for humans and can be used as an alloying agent and to produce pyrotechnic products. Phosphorous sulphides can be used to make matches, with phosphorus halides and oxides widely being used in the synthesis of organic compounds. Its flammable properties also lend to utilisation in military applications such as incendiary devices and smoke screens. Additional applications of phosphates also include organophosphorus detergents, insecticides, toothpaste, and oil additives.

Lithium iron phosphate (LFP) batteries – used in nearly half of all electric vehicles and in many large-scale energy storage facilities – require phosphorus. Phosphate rock is therefore listed by the European Union as a critical mineral for the green transition.

Steelmaking processes create large amounts of slag as a by-product, which are partially comprised of phosphates. Given that the approximate production of raw steel was 1.9 billion tonnes globally in 2022, significant quantities of phosphorus are contained in the by-products from steel manufacture. Although some cost-effective approaches to recovering high quality phosphate feedstocks from steelmaking slag have been demonstrated, the phosphorus extraction processes are not yet mature and scaleable for the purposes of LFP battery manufacture.