However, in addition to its use as a fertiliser, this versatile mineral has countless other uses. Phosphate-based products are found in applications as diverse as dishwasher detergents, leavening agents in baking, and in the manufacture of water-based paints. Phosphates also act as a preservative to retain moisture and flavour in packaged shrimp and ham. In its di-calcium and tri-calcium formulations, phosphate is even used to make bio-ceramic materials for bone replacement and prostheses.
There are more: phosphoric acid is used to add tartness to cola drinks and to chemically polish, or brighten, aluminium and aluminium alloys.
The acid is also used to protect (phosphatise) steel with a phosphate coating. Add to this countless applications for phosphorus-containing materials as flame retardants for textiles, plastics, paper and mastics and you can see why there is a growing demand for this useful mineral.
Urine sample
The story of phosphorus and its journey from detection to ubiquity has an unusual start. The element’s discovery is credited to German chemist Hennig Brand in 1669, after he is said to have accidentally stumbled upon phosphorus while distilling urine in his search for the philosopher’s stone, which would turn base metals into gold.
Instead of a lustrous metal he isolated a white, waxy material which he named phosphorus, or ‘bearer of light’, because it glowed in the dark.
A decade later, Robert Boyle, the English chemist, discovered the element independently. Boyle was the first to use phosphorus to ignite sulphur-tipped wooden splints, the forerunner of the modern match. A century later, Swedish chemists Johan Gahn and Carl Scheele showed that phosphate is present in bones as calcium phosphate; they even obtained elemental phosphorus from bone ash.
Fertile ground
In the 19th century, the discovery that phosphorus promotes growth in plants kicked off an agricultural revolution. Plants need phosphorus to grow as much as they do water, but many soils do not contain the element in sufficient quantities to meet the voracious demand of many food crops.
Initially, the soil was supplemented with ground bones as an agricultural fertiliser. In the latter half of the 19th century, bird and bat guano started to be ‘mined’ on tropical islands as an organic substitute.
Changes in the fertiliser industry started with the introduction of the electric arc furnace in 1890, which enabled inorganic phosphate rock to be used to produce phosphorus. The success of this new process coincided with the depletion of the world’s guano sources. As a result, mineral phosphates became the major source of phosphate fertiliser production.
Phosphate ore mining increased significantly after World War II in response to an increase in the global demand for fertilisers to increase food production. The ore remains the primary global source of phosphorus and phosphorus chemicals to this day.
Rising global demand
Today, 215 million tonnes of phosphate rock is mined around the globe in countries such as Morocco, the US, China and Australia. It is also mined in Brazil, where Anglo American’s phosphate operations are based. Situated principally in the state of Goiás, in the heart of Brazil’s farming region, Anglo American’s Niobium & Phosphates business is the second largest producer of phosphate fertiliser in the country, with an annual production of 1.39 million tonnes of phosphate concentrate.
Here, phosphate ore is mined and is then transformed into a product suitable for processing by beneficiation, a process which eliminates contaminants such as sand and clay. The concentrated ore is then transported to two processing plants. A strong domestic demand ensures 70 per cent of the open-pit mine’s output is used in fertiliser; further processing also produces di-calcium phosphate for the animal-feed industry as well as phosphoric and sulphuric acids.
Phosphates from Anglo American’s operation are helping Brazilian agriculture increase yields to meet growing demands. Brazil’s agricultural sector is the fastest growing in the world, while its phosphate fertiliser market, of which imports make up nearly 50 per cent, is fourth in the world. Growth is particularly strong in Goiás.
“The expectation is that Brazilian phosphate fertiliser consumption will increase at 5.2 per cent per year for the next four years,” says Marcos Stelzer, phosphates commercial director of Anglo American’s Niobium & Phosphates business.
In response to the growing demand, Anglo American’s plans include improvements to further enhance efficiency of the operation and, ultimately, to double phosphate production.
Demand for phosphate is rising globally. “World consumption of phosphorus fertilisers is projected to grow by two per cent every year up to 2020,” Stelzer says. The largest increases are expected in Asia and South America. In China, in particular, consumption of fertiliser is expected to grow in response to changes in the nation’s eating habits as the population becomes increasingly affluent.
Andy Pearson is a business writer, award-winning editor and former mechanical design engineer. He writes for various business and construction magazines and has recently contributed to a book on sustainability.
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