Publikationen

Rare earth elements and uranium in Minjingu phosphate fertilizer products: Plant food for thought

Nils H Haneklaus, Dennis A Mwalongo, Jacob B Lisuma, Aloyce I Amasi, Jerome Mwimanzi, Tomislav Bituh, Jelena Ćirić, Jakub Nowak, Urszula Ryszko, Piotr Rusek, Ali Maged, Essaid Bilal, Hajar Bellefqih, Khaoula Qamouche, Jamal Ait Brahim, Redouane Beniazza, Hamid Mazouz, Elizabet M van der Merwe, Wayne Truter, Hilda D Kyomuhimbo, Hendrik Brink, Gerald Steiner, Martin Bertau, Raghav S Soni, Ashwin W Patwardhan, Pushpito K Ghosh, Thomas T Kivevele, Kelvin M Mtei, Stanisław Wacławek

Erschienen in Resources, Conservation and Recycling, 2024/8/1, 207

Minjingu phosphate ore is Tanzania’s sole domestic supply of phosphorus (P). The ore contains medium to high concentrations of naturally occurring P2O5 (20–35 %) and relevant concentrations of uranium and rare earth elements (REEs) are also suspected to be present. Currently, neither uranium nor REEs are recovered. They either end up in mine tailings or are spread across agricultural soils with fertilizer products. This work provides a first systematic review of the uranium and REE concentrations that can be expected in the different layers of Minjingu phosphate ore, the way the ore is presently processed, as well as a discussion on alternative processing pathways with uranium/REE recovery. The study analyzed ten distinct Minjingu phosphate ore layers, four mine tailings, and five intermediate and final mineral fertilizer products from the Minjingu mine and processing plant located in northern Tanzania. The results confirm that the uranium concentrations and to a lesser degree, the REE concentrations are indeed elevated if compared to concentrations in other phosphate ores. The study does not identify a significant risk resulting from this. The development of techno-economic solutions for more comprehensive utilization of Minjingu ore is, however, strongly encouraged and suggestions on such processes are provided.

Can ultimate recoverable resources (URR) be assessed? Does analyzing declining ore grades help?

Wellmer, F.-W., Scholz, R. W., & Bastian, D. (2023

Erschienen in Mineral Economics, April 2023, Ausgabe 36,

Phosphate price peaks and negotiations – Part 2: The 2008 peak and implications for the future

Mew M.; Steiner G.; Haneklaus N.; Geissler B.

Erschienen in Journal of Resources Policy, Juni 2023, Ausgabe 83, 103588

This is Part 2 of a study examining the 1975 and 2008 price hike in the phosphate markets. While Part 1 of the companion paper introduces the system model and discusses the 1975 price hike in the phosphate market, Part 2 of the companion paper covers the major 2008 price hike, discusses similarities between the 1975 and 2008 price hike events and provides an outlook on the predictability and likeliness of future price hikes in the phosphate industry.

Phosphate price peaks and negotiations – Part 1: Fundamentals and the 1975 peak

Geissler B.; Steiner G.; Haneklaus N.; Mew M.

Erschienen in Journal of Resources Policy, Juni 2023, Ausgabe 83, 103587

Natural resources such as mineral commodities represent global assets of tremendous economic value for our modern-day society. Broadly speaking, the economic value in the form of the raw material price is related to their function, thus the demand for the commodity in interrelation to its supply. While most mineral commodities allow substitution, at least in the long-run, phosphorus is bio-essential and thus unsubstitutable

Uranium in phosphate rocks and mineral fertilizers applied to agricultural soils in East Africa

Mwalongo, DA.; Haneklaus, NH.; Lisuma, JB.; Kivevele, TT.; Mtei, KM.

Erschienen in Journal of Environmental Science and Pollution Research Radioanalytical and Nuclear Chemistry, November 2022, Ausgabe 11356

Phosphate rock, pre-concentrated phosphate ore, is the primary raw material for the production of mineral phosphate fertilizer. Phosphate rock is among the ffth most mined materials on earth, and it is also mined and processed to fertilizers in East Africa. Phosphate ore can contain relevant heavy metal impurities such as toxic cadmium and radiotoxic uranium. Prolonged use of phosphate rock powder as a fertilizer and application of mineral fertilizers derived from phosphate rock on agricultural soils can lead to an accumulation of heavy metals that can then pose an environmental risk. This work assesses the uranium concentrations in four major phosphate rocks originating from East Africa and four mineral phosphate fertilizers commonly used in the region.

Better filterability and reduced radioactivity of phosphogypsum during phosphoric acid production in Morocco using a fly ash waste and pure silica additive

Arhouni, F.E.; Hakkar, M.; Mahrou, A,; Belahbib, L.; Mazouz, H.; Haneklaus, N.; Pavón, S.; Bertau, M.; Boukhair, A.; Ouakkas, S.; Abdo, M.A.S.; Benjelloun, M.

Erschienen in Journal of Radioanalytical and Nuclear Chemistry, August 2022, Ausgabe 331, Issue 8

Reactive silica additives, such as clays, can increase the filterability of phosphogypsum (PG) during wet phosphoric acid production from phosphate rock (PR). In this study, the effect of adding inexpensive fly ash waste (34 kg per t PR) together with lower quantities of pure silica (8.5 kg per t PR) on the radioactivity of PG was investigated. The addition of fly ash waste/pure silica reduced the radiological activity of the PG by roughly 30%. The reduction was attributed to decreased activities from ²³⁸U (60% reduction) and ²²⁶Ra (30% reduction) in PG. Besides, P₂O₅ losses were slightly decreased.

The role of transdisciplinarity for mineral economics and mineral resource management: coping with fallacies related to phosphorus in science and practice

Scholz R.W.; Steiner G.

Erschienen in Mineral Economics, August 2022, Ausgabe 35, Issue 2

Mineral economics is a genuine multidisciplinary feld dealing with economic and policy matters related to the production, distribution, and consumption of mineral commodities. We discuss why the increasing complexity, ambiguity, ambivalence, and social contestation of subjects of mineral economics promote the participation of mineral economists in transdisciplinary processes. [...]

Closing the upcoming EU gypsum gap with phosphogypsum

Haneklaus, N.; Barbossa, S.; Basallote, M.D.; Bertau, M.; Bilal, E.; Chajduk, E.; Chernysh, Y.; Chubur, V.; Cruz, J.; Dziarczykowski, K.; Fröhlich, P.; Grosseau, P.; Mazouz, H.; Kiegiel, K.; Nieto, J.M.; Pavón, S.; Pessanha, S.; Pryzowicz, A.; Roubík, H.; Cánovas, C.R.; Schmidt, H.; Seeling, R.; Zakrzewska-Kołtuniewicz, G.

Erschienen in Published in Resources, Conservation and Recycling, July 2022, Ausgabe 182, 106328

The EU Renewable Energy Directive with climate and energy goals does not leave room for coal-burning power plants that currently contribute approximately 17 million t of flue gas desulfurization (FGD) gypsum to EU manufacturers that require a total of 57 million t of gypsum per year (EU, 2020). It is also unlikely that natural gypsum production in the EU can be significantly increased in the near-term. Unlike other critical raw materials (CRMs) such as rare earth elements (REEs) that constitute a relatively small volume and can be imported over long-distances, such practice is not economically feasible for this relatively inexpensive (per weight) bulk-commodity used in large quantities.

Rare earths in Philippine phosphogypsum: Use them or lose them

Ramirez, J.D.; Diwa, R.R.; Palattao, B.L.; Haneklaus, N.H.; Tabora, E.U.; Bautista VII, A.T.; Reyes, R.Y.

Erschienen in "The Extractive Industries and Society", Juni 2022, Ausgabe 10, 101082

The Mines and Geosciences Bureau of the Philippines is leaving no stone unturned in its quest to find rare earths to support the country's production sector. In this work we provide an analysis of the economic potential of rare earths found in Philippine phosphogypsum (PG), a powdery byproduct from phosphate fertilizer production. Approximately 10.1 million t PG that contain some 2,678 t rare earth oxides are accessible in the Philippines. PG is partly (up to 40% of the annual production) used in the cement industry and as soil conditioner in the Philippines today in which case accompanying rare earths are indefinitely lost.

Iron(III) removal and rare earth element recovery from a synthetic wet phosphoric acid solution using solvent extraction

Pavón, S.; Haneklaus, N.; Meerbach, K.; Bertau, M.

Erschienen in Minerals Engineering, May 2022, Volume 182, 107569
Phosphoric acid produced from phosphate rock is an intermediate product in mineral fertilizer production. Purification stages are commonly used to extract unwanted elements such as iron associated with the phosphate rock after the initial wet acid treatment. The current work presents a process that extracts iron(III) and recovers high-value rare earth elements (REEs) during phosphoric acid purification. A cross-flow solvent extraction process with four stages is used and a final raffinate with 684 mg/L P without losses during the process is obtained. Iron(III) removal (98.1 ± 0.7%) was achieved after the first two stages using Cyanex 572 as extractant.

Enhancing rare earth element transfer from phosphate rock to phosphoric acid using an inexpensive fly ash additive

Hakkar M.; Arhouni F.E.; Mahrou A.; Bilal E.; Bertau M.; Roy A.; Steiner G.; Haneklaus N.; Mazouz H.; Boukhair A.; Benjelloun M.

Erschienen in ScienceDirect, Oktober 2021, Volume 172, 107166
 

Adding active silica (SiO₂) to reduce the free fluoride content is a known method to improve the filterability of phosphogypsum (PG) during wet phosphoric acid (WPA) processing of phosphate rock (PR). Besides, this process can also promote the transfer of valuable rare earth elements (REE) from the PR into the liquid phosphoric acid (PA) stream rather than into the solid PG matrix from which later economic recovery is more challenging. Khouribga PR, that shows total REE concentrations of 577 ppm (328 ppm heavy REE and 249 ppm light REE) of which yttrium (Y) with 240 ppm constitutes the major fraction, is processed at the Jorf Lasfar El-Jadida chemical complex in Morocco that is also home to the country’s largest coal power plant. Fly ash produced during thermal power production, 70% of which is stacked in the immediate vicinity, presently remains mostly unused and consists largely (48%) of silica. In this work the use of fly ash (34 kg per t PR) and pure silica (8.5 kg per t PR) on the transfer of REE from Khouribga PR into the PA and PG stream during dihydrate WPA production was examined. The inexpensive fly ash/silica additive increases the transfer of various REE to the PA stream. For Y an increase of 37% was measured that resulted in a concentration of 48 ppm in the PA stream prior to further concentration by evaporation.

Uranium and other heavy metal sorption from Moroccan phosphoric acid with argan nutshell sawdust

Qamouche, K.; Chetaine, A.; El Yahayoui, A.; Moussaif, A.; Fröhlich, P.; Bertau, M.; Haneklaus, N.

Erschienen in ScienceDirect, September 2021, Volume 171, 107085

Argan nutshells, available in Morocco as a low-cost by-product from Argan oil production, were used to produce a sawdust biosorbent for the extraction of U and other heavy metals (Cd, As, Zn, Cu, Ni and Cr) from merchant-grade phosphoric acid (PA). Packed column (D = 20 mm, L = 250 mm, flowrate 1 mL/min) lab-scale experiments were carried out with three different solutions: (1) a synthetic heavy metals solution, (2) pure PA at different concentrations (0.85%, 8.5% and 85%) in water, and (3) merchant-grade PA from an industrial fertilizer plant in Morocco that was diluted with water to analyze different P₂O₅ contents (5%, 30% and 54%) and a U concentration of up to 157 ppm. The sawdust successfully adsorbed 99% of the U from (1) the synthetic solution and (2) the pure PA independent of the acid concentration. It further managed to adsorb more than half (54%) of U, 75% of Cd, 74% of As, 84% of Zn, 86% of Cu, 83% of Cr of the merchant-grade PA at 54% P₂O₅ content and a flow-rate of 1 mL/min. The sawdust was characterized by SEM and FTIR to understand the adsorption of metal ions. Column studies were carried out to know the breakthrough point. At breakthrough, the effluent volume was found to be 50 mL and the maximum adsorption capacity for U was found to be 0.93 mg/g. Heavy metal recovery using ANS does not seem to be promising as a result of the low (>10%) desorption rates if citric- or oxalic acid is used as was done in this study. Heavy metal extraction without direct recovery using ANS is promising and should further be investigated though.

Endangering the integrity of science by misusing unvalidated models and untested assumptions as facts: General considerations and the mineral and phosphorus scarcity fallacy

Scholz, R. W.; Wellmer, F. W.

Erschienen in Sustainability Science, März 2021

[...] Herein, we exemplarily elaborate how the integrity of science is endangered by normative solutionist and sociopolitically driven transition management and present mineral scarcity claims that ignore that reserves or resources are dynamic geotechnological-socioeconomic entities. We present the main mineral scarcity models and their fallacious assumptions. We then discuss the phosphorus scarcity fallacy, which is of particular interest as phosphorus is non-substitutable and half of all current food production depends on fertilizers (and thus phosphorus). We show that phosphorus scarcity claims are based on integrating basic geoeconomic knowledge and discuss cognitive and epistemological barriers and motivational and sociopolitical drivers promoting the scarcity fallacy, which affects high-level public media. [...]

Unconventional uranium in China’s phosphate rock: Review and outlook

Shang, D.; Geissler, B.; Mew, M.; Satalkina, L.; Zenk, L.; Tulsidas, H.; Barker, L.; El-Yahyaoui, A.; Hussein, A.; Taha, M.; Zheng, Y.; Wang, M.; Yao, Y.; Liu, X.; Deng, H.; Zhong, J.; Li, Z.; Steiner, G.; Bertau, M.; Haneklaus, N.

Erschienen im Renewable and Sustainable Energy Reviews, Volume 140,  April 2021, 110740

Some phosphate rock contains elevated concentrations of natural uranium. China is the largest phosphate rock producing country in the world and will soon have the largest uranium requirements in the world as well. Most phosphate rock deposits in China show low uranium concentrations (20–30 mg/kg) so that the recovery of radiotoxic heavy metals is neither economically appropriate nor ecologically necessary.

Thermal beneficiation of Sra Ouertane (Tunisia) low-grade phosphate rock.

Abbes, N./Bilal, E./Hermann, L./Steiner, G./Haneklaus, N.

Erschienen in Minerals 2020, 10(11), 937

Erschienen in Minerals Erschienen in Minerals 2020, 10(11), 937; Low-grade phosphate rock from Sra Ouertane (Tunisia) was beneficiated using a thermal treatment consisting of calcination, quenching, and disliming. Untreated phosphate rock samples (group 1), calcined phosphate rock samples (group 2), as well as calcined, quenched, and dislimed (group 3) phosphate rock samples, were investigated using inductively-coupled plasma atomic emission spectroscopy (ICP-AES), inductively-coupled plasma mass spectrometry (ICP-MS), thermogravimetric analysis (TGA), and X-ray powder diffraction (XRD). Besides, the particle size distribution of the aforementioned three groups was determined. The proposed thermal treatment successfully increased the P2O5 content of the untreated phosphate rock from 20.01 wt% (group 1) to 24.24 wt% (group 2) after calcination and, finally, 27.24 wt% (group 3) after calcination, quenching, and disliming. It was further found that the concentration of relevant accompanying rare earth elements (Ce, La, Nd, Pr, Sm, and Y) was increased and that the ...
 

Innovation potential along the phosphorus supply chain: A micro and macro perspective on the mining.

Geissler, B., Mew, M., Matschullat, J., Steiner, G.

Erschienen in Science of the Total Environment, 714, 2020.

Phosphorus is unique, given its characteristic of being essential for all life on Earth. The element is non-substitutable and finite in the form of highly concentrated phosphate-rock deposits. Thus, humankind should strive to utilize this resource in the most-efficient and sustainable manner.

Making Uranium Recovery from Phosphates Great Again?

Steiner, G., Haneklaus, N., Geissler, B.

Erschienen in Environmental Science & Technology, 54, 3, 1287–1289, 2020.

Uranium miners in the United States initiated the investigation, hoping for quotas on foreign uranium imports that would allow them to better compete with enterprises, often state-run and heavily subsidized, abroad. Quotas, if implemented, could, in fact, re-energize uranium mining in the U.S.

Phosphate supply security for importing countries: Developments and the current situation.

Geissler, B., Mew, M., Steiner, G.

Erschienen in Science of the Total Environment, 677: 511-523, 2019.

Cycling and Anthropogenic Use of Phosphorus in the 21st Century: Geoscientific and Geosocial Foundations of Agriculture

Scholz, R.W., Wellmer, F.-W.

Erschienen in Better Crops, 103(1), 9-12, 2019.

The global P cycle is considered from the perspective of geologic and historic timescales to help in the understanding of whether and when fundamental changes in agricultural practices for sustainable P may be needed.

Striving toward a phosphorus circular economy: The role of phosphate rock mining

Geissler, B., Hermann, L., Mew, M., Steiner, G.

Erschienen in Minerals, 8, 395, 2018.

As an element, phosphorus (P) is one of a kind. While it is essential for all life on Earth, phosphorus is neither substitutable nor infinite especially in terms of highly concentrated phosphate rock deposits. Society as a whole—and key stakeholders in particular—must build on and extend the idea of a linear system that begins with exploration, continues with extraction and processing, and ends with the application of fertilizers, by applying mechanisms of circularity

Sustainable Mineral Resource Management – Insights into the Case of Phosphorus

Steiner, G., Geissler, B.

Erschienen in Sustainability 10(8):2732, 2018.

Although it is among the most abundant elements in Earth’s crust (11th [1]) and water (13th [2]), phosphorus (P) is commonly referred to as “life’s bottleneck”, as “life can multiply until all the
phosphorus is gone, and then there is an inexorable halt which nothing can prevent.

Clearing the fog on phosphate rock data - Uncertainties, fuzziness, and misunderstandings

Geissler, B., Steiner, G., Mew, M.

Erschienen in Science of the Total Environment, 11(642): 250-263, 2018.

Big Data, blockchains, and cloud computing have become ubiquitous in today's mass media and are universally known terms used in everyday speech. If we look behind these often misused buzzwords, we find at least one common element, namely data. Although we hardly use these terms in the “classic discipline” of mineral economics, we find various similarities

Phosphorus Supply Chain—Scientific, Technical, and Economic Foundations: A Transdisciplinary Orientation

Mew, M., Steiner, G., Geissler, B.

Erschienen in Sustainability, 10(4): 1087, 2018.

Natural mineral resources, such as phosphates, represent global assets of tremendous economic value to stakeholders. Given its special characteristics and its essentiality for all life on Earth, phosphorus (P) bears additional value to society as it is both indispensable and not substitutable.

Peak minerals: What can we learn from the history of mineral economics and the cases of gold and phosphorus?

Wellmer, F.W., Scholz, R.W.

Erschienen 2016 in Mineral Resources, December 2016, pp 1-21.

Abstract: The objective of this paper is to provide a conceptual and empirical historic analysis of applications, misunderstandings, and fallacies surrounding the Hubbert curve, the U-shaped production curve of a commodity, and peak minerals. We show that the ultimate recoverable resources (URR) cannot be predicted by fitting a symmetric curve to the data of past (historic) production for any commodity on a global scale. Without knowledge of the URR, it is not possible to determine the peak production time. (...)

Efficiency performance of the world's leading corporations in phosphate rock mining

Bernhard Geissler, Michael C. Mew, Olaf Weber, Gerald Steiner

Erschienen in Resources, Conservation and Recycling, Volume 105, Part B, December 2015, pp. 246–258.

Abstract: The prominence of phosphorus (P) is represented by three major aspects: first and most important, P is essential for all life on Earth; second, no other element or substance can act as a substitute for P; and third, P is considered a non-renewable resource and thus finite. In regard to global food security and P as one of the three major macronutrients, the world faces an extensive challenge to utilize this finite and unsubstitutable commodity in the most effective as well as the most efficient way. Efficiency in general has increasingly become of major importance over the last several decades, especially within competitive commodities. [...]

Interactive comment on "Comment on: “Recent revisions of phosphate rock reserves and resources: a critique” by Edixhoven et al. (2014) – Phosphate reserves and resources: what conceptions and data do stakeholders need for sustainable action?” by R. W. Scholz and F.-W. Wellmer

B. Geissler and G. Steiner

Erschienen in Earth Syst. Dynam. Discuss., 6, C56–C68, 2015.

The following comment addresses especially the discussion paper by Scholz and Wellmer (2015), which focuses on phosphate reserves and resources, as a comment on ‘Recent revisions of phosphate rock reserves and resources: a critique’ by Edix- hoven, Gupta, and Savenije (2014). Additionally, the ongoing discussions and contributions by experts within the field like Cook (2014), Hilton (2013), Mew (2015) and, certainly, the origin of the discussion by Edixhoven, Gupta, and Savenije (2013) and the corresponding comments from Scholz and Wellmer (2013).

Efficiency developments in phosphate rock mining over the last three decades

Gerald Steiner, Bernhard Geissler, Ingrid Watson, Michael C. Mew

Erschienen in Resources, Conservation and Recycling, Volume 105, Part B, December 2015, Pages 235–245.

Abstract: This paper appraises losses and efficiency in phosphorus mining processes. The distinction between resource and economic efficiency as crucial determinants of the mining decision process is outlined in relation to the kind of agents involved. Second, we apply a system and process approach to visualize and better deal with the complexity of the phosphorus supply chain and to provide a framework of the extended phosphorus supply chain for subsequent efficiency analyses. (...)

Sustainable Phosphorus Management A Global Transdisciplinary Roadmap

Scholz, R.W., Roy, A.H., Brand, F.S., Hellums, D., Ulrich, A.E. (Eds.)

Erschienen 2014, Springer Verlag.

Abstract: This book describes a pathway for sustainable phosphorus management via the Global Transdisciplinary Processes for Sustainable Phosphorus Management project (Global TraPs). Global TraPs is a multi-stakeholder forum in which scientists from a variety of disciplines join with key actors in practice to jointly identify critical questions and to articulate what new knowledge, technologies and policy processes are needed to ensure that future phosphorus use is sustainable, improves food security and environmental quality and provides benefits for the poor. The book offers insight into economic scarcity and identifies options to improve efficiency and reduce environmental impacts of anthropogenic phosphorus flows at all stages of the supply and use chain.

Review on "Sustainable Phosphorus Management"

Ecological Economics 114 (2015) 245–246

Future Phosphate Rock Production – Peak or Plateau?

Michael Mew, Director, Fertecon Research Centre Limited

Erschienen Fertecon Research Centre Limited—A Matter of Opinion. 2009

Hubbert's Peak Oil theory is more than 60 years old, yet is still to be shown conclusively to describe the real oil world. Its derivative, Peak Phosphorus was first coined just four years ago, and yet discussion has already been moved on to when the peak will occur rather than whether the model adequately describes the phosphate industry at all. This work looks at the potential flaws in the model, discussing why, if anything, it is the substitutability of oil within the energy system that is more likely to be the factor implicit in determining the peak nature of the production curve rather than the fact that oil itself is a non-renewable resource.