Explore the vast range of titles available.

Recently, microcrystallization technology has gained much interest because of the enhanced dissolution of the target sample and promotion of the sustainable development of agriculture. Phosphorus (P) is one of the most important nutrients for increasing crop yield; the increase in effective P ratio directly from raw phosphate rock (PR) powder by mechanical grinding to increase its microcrystallinity is believed to be the best choice for this purpose. This study reports the improvement in the activation property of PR powder with different lignite ratios (1%, 2%, 3%, and 5%), particularly the relationship between particle-size distribution, specific surface area, granule morphology, and the citric acid-soluble P. It was found that a 3% lignite addition was the optimal treatment for increasing the release of citric acid-soluble P. The maximum total amount of dry matter from rapeseed cultivation and the available P after the test increased by 56.1% and 89.6%, respectively, with direct use of PR and microcrystallized PR powder (PR2), compared with the control test without any addition of phosphate minerals.

This compilation from the 2018 Beneficiation of Phosphates Conference includes insights from dozens of internationally respected experts on key breakthroughs that will shape the industry in the years ahead. Learn from the best and the brightest in the industry. The book reflects on the recent impetus for reviewed research in the recovery of rare earth elements from secondary resources. Recovery of rare earth elements from phosphate processing has been one of the important projects of the Critical Materials Institute (CMI). This compilation highlights some of the findings of the CMI phosphate project. Learn how competition in the flotation reagent market has stimulated innovative reagent development work. As a result, new reagents have been formulated and targeted at dolomite flotation, calcite flotation, more selective phosphate flotation, and even flotation in seawater. The Florida phosphate industry is seeing improvements in the processing of high dolomite reserves.

Phosphorus (P) is critical to modern biochemical functions and can control ecosystem growth. It was presumably important as a reagent in prebiotic chemistry. However, on the early Earth, P sources may have consisted primarily of poorly soluble calcium phosphates, which may have rendered phosphate as a minimally available nutrient or reagent if these minerals were the sole source. Here, we review aqueous P availability on the early Earth (>2.5 Gyr ago), considering both mineral sources and geochemical sinks relevant to its solvation, and activation by abiotic and biological pathways. Phosphorus on Earth’s early surface would have been present as a mixture of phosphate minerals, as a minor element in silicate minerals, and in reactive, reduced phases from accreted dust, meteorites and asteroids. These P sources would have weathered and plausibly furnished the prebiotic Earth with abundant and potentially reactive P. After the origin of a biosphere, life evolved to draw on not just reactive available P sources, but also insoluble and unreactive sources. The rise of an ecosystem dependent on this element at some point forged a P-limited biosphere, with evolutionary stress forcing the efficient extraction and recycling of P from both abiotic and biotic sources and sinks.A review of aqueous phosphorus availability on the Earth’s early surface suggests a range of phosphorus sources supplied the prebiotic Earth, but that phosphorus availability declined as life evolved and altered geochemical cycling.

Recent research has demonstrated the applicability of a biotechnological approach for extracting base metals using acidophilic bacteria that catalyze the reductive dissolution of ferric iron oxides from oxidized ores, using elemental sulfur as an electron donor. In Brazil, lateritic deposits are frequently associated with phosphate minerals such as monazite, which is one of the most abundant rare-earth phosphate minerals. Given the fact that monazite is highly refractory, rare earth elements (REE) extraction is very difficult to achieve and conventionally involves digesting with concentrated sodium hydroxide and/or sulfuric acid at high temperatures; therefore, it has not been considered as a potential resource. This study aimed to determine the effect of the bioreductive dissolution of ferric iron minerals associated with monazite using Acidithiobacillus (A.) species in pH- and temperature-controlled stirred reactors. Under aerobic conditions, using A. thiooxidans at extremely low pH greatly enhanced the solubilization of iron from ferric iron minerals, as well that of phosphate (about 35%), which can be used as an indicator of the dissolution of monazite. The results from this study have demonstrated the potential of using bioreductive mineral dissolution, which can be applied as pretreatment to remove coverings of ferric iron minerals in a process analogous to the bio-oxidation of refractory golds and expand the range of minerals that could be processed using this approach.

Highly ordered TiO.sub.2 nano-pillar arrays were deposited on the Ti foils by a hydrothermal method, using aqueous solutions of TiOSO.sub.4. The vertical nano-pillars with diameters in tens of nanometers strongly attached on the Ti foil and densely covered the whole surface. The structural studies clearly showed that the nano-pillars were pure tetragonal rutile TiO.sub.2 phase. [001] was the preferential growth direction. Based on the experimental results, a model for the in situ deposition of TiO.sub.2 with high-energy facet exposed is given. The growth mechanism was interpreted in terms of the lattice matching between the growing nano-structural titania and Ti, and the thermodynamic stability of the rutile lattice planes. The obtained TiO.sub.2 crystallographic plane with high energy induced apatite nucleation in less than 1 day and exhibited good in vitro bioactivity.

We provide evidence that citrate anions bridge between mineral platelets in bone and hypothesize that their presence acts to maintain separate platelets with disordered regions between them rather than gradual transformations into larger, more ordered blocks of mineral. To assess this hypothesis, we take as a model for a citrate bridging between layers of calcium phosphate mineral a double salt octacalcium phosphate citrate (OCP-citrate). We use a combination of multinuclear solid-state NMR spectroscopy, powder X-ray diffraction, and first principles electronic structure calculations to propose a quantitative structure for this material, in which citrate anions reside in a hydrated layer, bridging between apatitic layers. To assess the relevance of such a structure in native bone mineral, we present for the first time, to our knowledge, ¹⁷O NMR data on bone and compare them with ¹⁷O NMR data for OCP-citrate and other calcium phosphate minerals relevant to bone. The proposed structural model that we deduce from this work for bone mineral is a layered structure with thin apatitic platelets sandwiched between OCP-citrate–like hydrated layers. Such a structure can explain a number of known structural features of bone mineral: the thin, plate-like morphology of mature bone mineral crystals, the presence of significant quantities of strongly bound water molecules, and the relatively high concentration of hydrogen phosphate as well as the maintenance of a disordered region between mineral platelets.

The root cap has a fundamental role in sensing environmental cues as well as regulating root growth via altered meristem activity. Despite this well-established role in the control of developmental processes in roots, the root cap's function in nutrition remains obscure. Here, we uncover its role in phosphate nutrition by targeted cellular inactivation or phosphate transport complementation in Arabidopsis, using a transactivation strategy with an innovative high-resolution real-time 33 P imaging technique. Remarkably, the diminutive size of the root cap cells at the root-to-soil exchange surface accounts for a significant amount of the total seedling phosphate uptake (approximately 20%). This level of Pi absorption is sufficient for shoot biomass production (up to a 180% gain in soil), as well as repression of Pi starvation-induced genes. These results extend our understanding of this important tissue from its previously described roles in environmental perception to novel functions in mineral nutrition and homeostasis control.

The minerals of the triphylite, alluaudite, zwieselite, and graftonite groups are amongst the most abundant of the primary phosphate minerals in granitic pegmatites. An analysis of the crystal structures of the four groups from the perspective of the connectivity between the metal atom polyhedra and the PO.sub.4 tetrahedra for the individual metal atom sublattices has resulted in the identification of structural motifs that are common to the four primary mineral groups. All four structure types contain 2-polyhedra-wide ribbons formed from corner linking of M.sub.2 (PO.sub.4).sub.2 ?.sub.8 cyclic tetramers, oriented along [001]. The ribbons in the four structure types all have the same topology but correspond to different geometrical isomers due to different orientations of the tetrahedra and different pairs of polyhedral edges involved in the ribbon formation. In the alluaudite, zwieselite, and graftonite group minerals, the polymerised cyclic tetramer (PCT) ribbons are connected along [010] by octahedral edge sharing, giving the same topology of (100) layers, with correspondingly similar b and c unit-cell parameters for the structures of the three mineral groups. The same PCT ribbons are also present in arrojadite-dickinsonite group primary phosphates. The persistent presence of the same type of structural unit across several different mineral groups is related to the high flexility of the cyclic tetramers to adjust to different crystal chemistries by rotation and buckling about the polyhedral corner linkages.

Phosphate ore is an important raw material for manufacturing fertilizers and phosphorous chemical products. While most of the phosphate resources cannot be directly treated as feed stock due to the low grade of P2O5 and high content of impurities. In order to obtain a qualified phosphate concentrate, the beneficiation of the low-grade phosphate ore is, hence, of great necessity. Many beneficiation techniques can be employed to upgrade the P2O5 grade of phosphate ores based on their characteristics in chemical composition and texture. The flotation process is most widely applied to balance the P2O5 recovery ratio and cost. In this review, the dominant techniques for the beneficiation of phosphate ores are introduced. Moreover, the factors that affect the flotation of phosphate ore, including the properties of mineralogy, flotation reagents (depressants and collectors) and flotation medium, were systematically analyzed.