Dynamic of Heavy Metals and Environmental Impact of Waste Phosphogypsum

Abstract

The production of phosphoric acid from natural phosphate rock by the wet process gives rise to an industrial by-product called phosphogypsum. About 5 tons of phosphogypsum are generated per ton of phosphoric acid production, and worldwide phosphogypsum generation is estimated to be around 100–280 Mt per year. This co-product is mostly disposed of without any treatment, usually by dumping in large stockpiles. These are generally located in coastal areas close to phosphoric acid plants, where they occupy large land areas and cause serious environmental damage. Phosphogypsum is mainly composed of gypsum but also contains heavy metals and other trace elements. All of this adds up to a negative environmental impact and many restrictions on phosphogypsum applications. Up to 15% of world phosphogypsum production is used to make building materials, as soil amendment, and as a set controller in the manufacture of Portland cement; uses that have been banned in most countries.