Evaluation of the recovery of Rare Earth Elements (REE) from phosphogypsum waste – case study of the WIZÓW Chemical Plant (Poland)

Abstract

More than 5 million tons of apatite phosphogypsum, a waste derived from the production of phosphoric acid, have been tipped on the waste tip of the Wizów Chemical Plant (Poland). This waste contains Rare Earth Elements (REE) which are on the list of ‘critical’ raw materials in the EU and other countries. This paper presents an evaluation of the industrial waste management solutions in the Wizów plant. Technology has been developed that enables one to eliminate the landfilling of the phosphogypsum by converting the waste into commercial products: anhydrite and REE concentrates (wasteless technology). In this study, the impacts of landfilling (1st variant) and the implementation of improvement – REE recovery (2nd variant) were explored taking into account both economic and environmental aspects. The two variants of waste management in Wizów were assessed using the Life Cycle Assessment (LCA) method. The functional unit was 1 Mg of waste. Analyses were performed using the generic data (‘input’ and ‘output’) from the existing plant and from a technological plan proposed for REE recovery. The identification of factors affecting the environment was the basis for determining the environmental and developmental target and the basis for exploring modified technological solutions. The Eco-Indicator 99 (EI′99) method was applied. The evaluation of economic efficiency using the LCNPV method was based on calculations of technological plans, cost estimates and the market prices of raw materials. For validation, the results of exergy assessment were also proposed. The results of the analyses carried out using EI′99 indicate that disposal of waste has much less impact on the environment (Pt 4.58) than the proposed technology for processing it (Pt 8.28), even though in the new technology one takes into account the potential beneficial environmental impacts associated with the new materials: REE concentrates and anhydrite. The technology developed requires significant investment, but it can provide additional raw materials due to the possibility of REE recovery. There are considerable ecological benefits for plants generating phosphogypsum waste since the utilisation of all current production wastes would end phosphogypsum storage and turn the manufacturing process for extracting phosphoric acid into a low-waste production process, which is consistent with the targets of a circular economy. Moreover, the technology proposed in this paper should help to incentivise the global recovery of REE and facilitate the launching of new production activities due to the possibility of its application in other plants generating a large amount of phosphogypsum waste.