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Rare earth elements are a set of seventeen chemical elements in the periodic table—the fifteen lanthanides plus scandium and yttrium. These unusual metals are important in many technologies, including electronics, computers, clean energy, health care, transportation, national defense, and others. Despite their name, they are not all that rare, but unlike typical minerals they are rarely found in pockets or seams and are instead dispersed in low levels of concentration. Recovering REEs can be difficult and expensive. At present, the United States imports nearly all of its rare earth elements. Doctoral student Dave DeSimone and seniors Taylor Forrest and Nick Dement recently traveled to the Florida Industrial and Phosphate Research Institute (FIPR) to test a developmental process for recovering REEs from various waste streams from the phosphate industry. These tests were made possible by collaboration between UT, Oak Ridge National Laboratory (ORNL), Idaho National Laboratory, and FIPR through the Critical Materials Institute. The project is coordinated by Professors Robert Counce and Jack Watson at UT, David DePaoli at ORNL, and Patrick Zhang at FIPR. "Our interaction with UT students on this project has been valuable in two ways," said DePaoli. "The students have gained a vital educational experience, one that benefited the project through their analyses in prioritizing the phosphate byproducts in terms of their potential as REE source materials. "Also, their recent tests have yielded valuable practical information toward the viability of REE recovery options that would not be accessible through typical laboratory experimentation." Prior to the Florida investigation, four teams of UT seniors developed conceptual processes and ranked the potential for recovery of REE from phosphate waste streams. They briefed ORNL and FIPR weekly, producing reports of their design and analysis activities. The project holds vast importance for the United States, as highlighted by the Department of Energy's Critical Materials Institute. "The DOE found that four clean energy technologies—wind turbines, electric vehicles, photovoltaic cells, and fluorescent lighting—use rare earth elements that are at risk of supply disruption in the next five years," said Counce. "The objective of our work is to evaluate possible routes for recovery of rare earth elements from waste streams from phosphate processing." In addition to the high-end devices, REEs also play key roles in such everyday items as magnets, rechargeable batteries, mobile devices, and superconductors. Because of that, any way of making them more accessible could have drastic, far-reaching effects across a number of areas. DePaoli said the United States currently imports nearly all of its rare earth elements, but that the method being developed could change that dramatically. "While we're a major importer of rare earth materials, we're actually the world's second biggest producer of phosphates, with 32 million metric tons being produced each year," said DePaoli, who, like Watson, also serves as an adjunct professor in the Department of Chemical and Biomolecular Engineering at UT. "This represents a significant potential source of relevant materials, since currently mined phosphate materials contain rare earth elements as well." DeSimone, who leads UT's student team, described the basic concept behind the breakthrough, noting that the phosphate industry uses sulfuric acid as part of their process. With the introduction of a stream of solvent alongside the acid, rare earth elements can be separated from the acid and brought into use. Doing so could potentially introduce a new source of rare earth elements while avoiding the need for new mining. "That was one of the big plusses of this approach," said DeSimone. "Being able to tap into what is basically a byproduct of another process and harness it for such a critical resource is a major development." Explore further: Recycling: A new source of indispensible 'rare earth' materials mined mainly in China Provided by: University of Tennessee at Knoxville

Shou L.,University of Florida | Theodore A.,University of Florida | Wu C.-Y.,University of Florida | Wu C.-Y.,National Cheng Kung University | And 2 more authors.
Aerosol and Air Quality Research | Year: 2012

Conventional denuders made of glass or metal are too heavy and bulky to be used in personal sampling systems. In this study, a portable Porous Membrane Denuder (PMD) was developed for personal sampling. The PMD utilizes the porosity of the membrane material and a configuration of multiple parallel flow channels to reduce the size and weight of the device, while increasing the gas collection efficiency. Four types of PMDs (PMD I, II, III and IV) with increasing numbers of channels and smaller channel openings were constructed and tested. Using 10% sodium carbonate coating and a feed concentration of 1 ppm, PMD Ia's collection efficiency for sulfur dioxide over 8 hours was higher than 99.9%. For a feed concentration of 10 ppm, the 5-hr time-weighted-average collection efficiency for sulfur dioxide was 73.1%, 82.8%, 90.9%, 97.2% for PMD Ib, II, III and IV, respectively, compared with 96.6% of the Glass Honeycomb Denuder (GHD), which has similar structure to PMD IV. However, the weight of PMD IV is only one-tenth of that of the GHD. It is clear that with a similar physical structure, PMDs have similar capacities to traditional Glass Honeycomb Denuders, yet are much lighter and less expensive. This study demonstrates the great potential of this new type of denuder for many applications in the field of environmental and industrial hygiene monitoring. Particle loss fractions of the four types of PMDs in the size range of 1 to 10 μm were also measured and were 2.9%, 5.2%, 5.7% and 7.3%, respectively.© Taiwan Association for Aerosol Research.

Chien C.-H.,University of Florida | Theodore A.,University of Florida | Wu C.-Y.,University of Florida | Hsu Y.-M.,Wood Buffalo Environmental Association | Birky B.,Florida Industrial and Phosphate Research Institute
Journal of Aerosol Science | Year: 2016

Converting optical diameter measured by an optical particle counter (OPC) to aerodynamic diameter measured by an aerodynamic particle sizer (APS) is of interest because the OPC is more affordable and portable. In this study, optical diameter was compared with volume equivalent diameter derived from aerodynamic diameter using monodisperse oleic acid and sodium chloride test aerosols generated by a Vibrating Orifice Aerosol Generator (VOAG). While prior studies assumed optical diameter to be equal to volume equivalent diameter, experimental results showed the assumption to be valid only if the aerosol has the same optical properties as standard polystyrene (PSL) particles. For oleic acid aerosol, the optical diameter was less than the derived volume equivalent diameter because its refractive index (m=1.46) is less than of PSL (m=1.60). While the refractive index of sodium chloride (m=1.54) is close to that of PSL, a much larger optical diameter of sodium chloride than its volume equivalent diameter was observed due to its irregular crystallography. Regression equations derived from the calibration were verified by testing with a validated respirable sampler. With known refractive index and shape factor, these equations can convert optical diameter directly to aerodynamic diameter with a residual bias less than 1 µm. © 2016 Elsevier Ltd

Zhang P.,Florida Industrial and Phosphate Research Institute | Stana R.,R-Squared | El-Shall H.,University of Florida | Moudgil B.,University of Florida
Mineral Processing and Extractive Metallurgy: 100 Years of Innovation | Year: 2014

This paper reviews significant technological developments in phosphate processing, which have been applied on an industrial scale. It covers phosphate mineral processing, phosphoric acid manufacturing, analysis and process control, and waste treatment and utilization. Nothing improved the industry efficiency more dramatically than the development and commercialization of the Crago "Double Float" flotation process for processing low-grade siliceous phosphate ores. The development and adoption of the direct-reverse flotation process for removing dolomite from sedimentary phosphate has the potential to at least triple the world phosphate reserves. Installations of on-line analyzers based on the NMR (Nuclear Magnetic resonance) and LIBS (Laser Induced Breakdown Spectroscopy) technologies have resulted in significant efficiency improvements. Huge energy saving and environmental benefits have been achieved by the transformation of phosphoric acid manufacturing from the thermal method to the "wet acid" process, which was made possible by industrialization of the dihydrate and hemihydrate processes. Recovery of uranium from phosphoric acid played an important role in increasing the world energy resource. Large scale utilization of phosphogypsum has taken off in many parts of the world. The concept of "green mine" (comprehensive recovery of mineral resources and complete waste utilization) has become a reality at some phosphate complexes.

Zhang P.,Florida Industrial and Phosphate Research Institute | Zhang P.,University of Florida | El-Shall H.,Florida Industrial and Phosphate Research Institute | El-Shall H.,University of Florida
Minerals and Metallurgical Processing | Year: 2012

This paper gives a review of promising technologies for phosphate processing, and covers flotation, analysis and process control, as well as tailings treatment and utilization. Air bubbles of less than a μm in size, combined with relatively large bubbles, have been demonstrated, both in the lab and on a pilot scale, to improve flotation dramatically, by reducing reagent use while improving product grade. Innovative use of polymers has allowed rapid dewatering of fine tailings with a final product that does not segregate. The first online laser-induced breakdown spectroscopy (LIBS) analyzer was created, allowing rapid analysis of wet samples using the laser technology. Many large commercial projects are successfully pursuing the utilization of phosphogypsum.

Xiao W.D.,Wuhan University | Yang X.,Wuhan University | Zhang P.,Florida Industrial and Phosphate Research Institute
Minerals and Metallurgical Processing | Year: 2015

A process mineralogy study was conducted to guide the development of a process for the extraction of vanadic oxide (V2O5) and aluminum compounds from bone coal and its ash as well as the production of byproducts. Results show that to extract the targeted metals at higher recovery rates, one must find a suitable agent capable of destroying the structure of the mica and breaking down the lattices in which these metal-bearing minerals occur. For such minerals, metal extraction efficiency is usually low if the approach is simply adding an oxidant that cannot destroy the structure. In this research, a byproduct fluosilicic acid (H2SiF6) at 20 percent concentration from an operating phosphate fertilizer plant was found to be powerful and effective for the leaching of vanadium-bearing minerals such as mica. This environmentally friendly process improved the leachability of valuable constituents in the bone coal significantly, with the leaching rate of V2O5 increased to 94 percent, from 83 percent, and that of aluminum oxide (Al2O3) increased to 75 percent, from 40 percent. X-ray diffraction and chemical analyses showed that the structure of mica can be destroyed using fluosilicic acid either alone or in combination with sulfuric acid. Based on the process mineralogy study, a processing flowsheet was tested, which resulted in a final V2O5 powder product with purity of 99.2 percent and an overall recovery rate of higher than 85 percent. The flowsheet consists of leaching, ion exchange and ammonium precipitation. With this process, various byproducts could also be generated, including aluminum fluoride, cryolite, aluminum sulfate, calcium sulfate, ammonium chloride, sodium chloride and cement admixtures. Copyright 2015, Society for Mining, Metallurgy & Exploration Inc.

Zhang P.,Florida Industrial and Phosphate Research Institute | Zheng S.,China Bluestar Lehigh Engineering Corporation | Sun W.,China Bluestar Lehigh Engineering Corporation | Ma X.,China Bluestar Lehigh Engineering Corporation | Miller J.,University of Utah
2014 SME Annual Meeting and Exhibit, SME 2014: Leadership in Uncertain Times | Year: 2014

A 1989 FIPR characterization study of the future phosphate resources in Florida showed that MgO would be a problem with both the pebble and concentrate as phosphate mining moves deeper. Since the ratio of concentrate to pebble will become higher and higher In the future, reducing Mg content in the concentrate by a small margin would allow blending of a large portion of the high-dolomite pebble. This research was conducted based on that logic. The following six approaches were tested for reducing MgO content in the flotation concentrate: (1) Adding a dolomite depressant in the rougher flotation step; (2) Dolomite flotation on the rougher concentrate with and without grinding; (3) Dolomite flotation on the cleaner concentrate with and without grinding; (4) Scrubbing the flotation feed; (5) Scrubbing the rougher concentrate; (6) Scrubbing the cleane r concentrate. Successful methods Include adding a dolomite depressant in the rougher flotation, olomite flotation on the cleaner concentrate with grinding, and scrubbing the cleaner concentrate in quartz sand. These techniques could reduce MgO content in the final concentrate by 20-40%. The flotation process could achieve a concentrate with the lowest MgO content, but it is the most expensive approach. Adding a dolomite is inexpensive and easy, but the effect is limited. Overall, scrubbing may be the most promising technology for this purpose.

Han Y.,Northeastern University China | Lei L.,Northeastern University China | Yuan Z.,Northeastern University China | Wang Z.,Northeastern University China | Zhang P.,Florida Industrial and Phosphate Research Institute
Minerals and Metallurgical Processing | Year: 2012

The characteristics of comminuted hematite products using a high pressure grinding roller (HPGR) and con ventional jaw crusher (JC) were comparatively studied by screening, optical microscope, scanning electron microscope (SEM) and Brunauer, Emmett and Teller (BET) techniques. Major properties investigated included product size distribution, particle cracks, specific surface areas and pore volumes. Results showed that in a closed-circuit operation with a screen opening of 3.2 mm, the HPGR and JC gave a similar P 80, but the HPGR achieved a more uniform size distribution, more fines and a higher crushing efficiency. Three modes of cracks were identified, namely transgranular cracks, innergranular microcracks and intergranular microcracks. Transgranular cracks originated from shearing breakage. Innergranular and intergranular microcracks were generated by HPGR via the two main nonrandom breakage forms, preferential breakage and interfacial breakage, depending on their respective ability to endure stresses when mineral phases (particles) were loaded against each other. The BET values for the same-size fractions showed that HPGR products gave higher specific surface areas and more pore volumes than JC products. This indicates that HPGR-crushed products are easier to grind because of their high porosity and extra cracks. © Copyright 2012 Society for Mining Metallurgy and Exploration Inc.

Zhang P.,Florida Industrial and Phosphate Research Institute | Snow R.,Florida Industrial and Phosphate Research Institute | Song W.,China Bluestar Lehigh Engineering Corporation | Ma X.,China Bluestar Lehigh Engineering Corporation | Zheng S.,China Bluestar Lehigh Engineering Corporation
IMPC 2014 - 27th International Mineral Processing Congress | Year: 2014

Numerous phosphate mineral depressants have been reported in the literature for use during anionic flotation of dolomite from carbonate fluorapatite in slightly acid circuits. In one part of this research, laboratory flotation experiments were conducted to compare the effectiveness of phosphate depressants to process ground, deslimed high-MgO Florida phosphate pebbles. Ten potential phosphate depressants were evaluated during laboratory anionic flotation of dolomite from phosphate in a slightly acid circuit using a sulfonated oleic acid soap plus oil as the dolomite collector. Eight of the depressants have been used by various investigators with foreign and domestic carbonate-phosphate ores. Four of the depressants were found to be reasonably effective during the current flotation study, namely: sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP), tetrasodium pyrophosphate (TSPP) and diphosphonic acid (DPA). Without depressants, the sulfonate collector required to produce cell underflow phosphate products containing <0.80% MgO and MgO/P2O5 ratio <.033 was 1.13 kg/ton of flotation feed at a flotation pH range = 5.5-6.0. Using this collector level with 0.91-1.36 kg/ton of feed of STPP, SHMP or TSPP yielded phosphate products analyzing 0.73-0.92% MgO and MgO/P2O5 ratios =.027-.034 at 90.0-96.8% P2O5 recovery. Similar grade phosphate products were obtained using DPA as the phosphate depressant at 84.1-87.5% P2O5 recovery. When no depressant was used, a similar grade phosphate product was obtained at only 65.9% P2O5 recovery. Another part of the research aimed at reducing MgO content in the final concentrate from Florida phosphate plants by conducting dolomite flotation on the final concentrate. Numerous phosphate depressants were tested for this purpose, including acidic, neutral and alkaline reagents. The most effective phosphate depressant was found to be phosphoric acid, giving both high grade and recovery.

Zhanga P.,Florida Industrial and Phosphate Research Institute
Procedia Engineering | Year: 2014

It is well known that phosphate is a non-renewable resource essential for plant growth and crop production, and it is, therefore, vital to feeding the fast growing population of the world. But it is not widely aware that there are many other valuable elements in phosphate ore, which may play significant roles in the development of future energy, particularly green energy, high tech equipment, and advancement of various key technologies. These elements include rare earths, uranium and thorium. Uranium in phosphate accounts for more than 80% of the world unconventional uranium resources, while rare earth elements in the world's annual production of phosphate rock (about 170 million tons) total nearly 100,000 tons. If these elements are not recovered during phosphate mineral processing and phosphoric acid manufacturing, they mostly end up in fertilizers and eventually being spread on farm lands, making it impossible to ever recover. Based on a review of selected research and development papers, the author provides his viewpoint of treating phosphate ore as an energy mineral, and suggests several approaches for recovering energy values from phosphate as well as for treatment and utilization of wastes associated with phosphate mining and processing. © 2014 The Authors. Published by Elsevier Ltd.

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