scholarly journals Grain Size Distribution and Clay Mineral Distinction of Rare Earth Ore through Different Methods

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 353 ◽  
Author(s):  
Lingkang Chen ◽  
Xiongwei Jin ◽  
Haixia Chen ◽  
Zhengwei He ◽  
Lanrong Qiu ◽  
...  
Keyword(s):  
Grain Size ◽  
Rare Earth ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Solution Concentration ◽  
Low Ph ◽  
Low Grade ◽  
Leaching Rate ◽  
Leaching Solution

Although clay mineral content in ion-absorbed rare earth ores is crucial for migrating and releasing rare earth elements, the formation, distribution, and migration of clay minerals in supergene rare earth ores have not been fully understood. Therefore, this study analyzes the characteristics of clay mineral type and content, soil particle size, pH value, leaching solution concentration, and leaching rate. This analysis was performed using different methods, such as regional rare earth mine soil surveys, in situ leaching profile monitoring, and indoor simulated leaching. The results showed that the grain size and volume curve of rare earth ore have unimodal and bimodal shapes, respectively. X-ray diffraction showed the differences in clay mineral types formed by different weathered bedrocks. The principal clay minerals were kaolinite, illite, chlorite, and vermiculite, with their relative abundance varying with parent rock lithology (granite and low-grade metamorphic rocks). In the Ganxian granite weathering profile, the kaolinite content increased from top to bottom. The decomposition of feldspar minerals to kaolinite was enhanced with an increase in the SiO2 content during weathering. The in situ leaching profile analysis showed that the kaolinite content increased initially and then decreased, whereas the illite/mica content exhibited the opposite trend. Under stable leaching solution concentration and leaching rate, clay mineral formation is favored by lower pH. Low pH, low leaching rate, and highly-concentrated leaching solution (12 wt%) resulted in a slow increase in kaolinite content in the upper part of the profile (30 cm). A lower concentration of the leaching solution (4 wt%) resulted in rapid enrichment of kaolinite after 15 days. Low pH, leaching solution concentration, and leaching rate promoted the formation of distinct kaolinite horizons. We suggest that by disregarding other control factors, rare earth recovery of over 90% can be achieved through leach mining with solutions of 8 wt% and a pH of 5 at a leaching rate of 5 mL/min.

scholarly journals Influence of grain size on chalcopyrite ore leaching in acidic medium

2007 ◽  
Vol 72 (8-9) ◽  
pp. 911-919 ◽  
Author(s):  
M.M. Antonijevic ◽  
G.D. Bogdanovic ◽  
S.M. Serbula ◽  
S.M. Milic
Keyword(s):  
Grain Size ◽  
Dissolved Oxygen ◽  
Sulphuric Acid ◽  
Acidic Medium ◽  
Raw Material ◽  
Leaching Rate ◽  
Acid Consumption ◽  
Leaching Solution ◽  
Chalcopyrite Ore

This work presents an investigation of column leaching of a chalcopyrite ore using sulphuric acid where dissolved oxygen and iron(III) ions play the role of oxidants. The investigations were carried out in PVC columns, diameter 110 mm and height 1000 mm, by percolation of the leaching solution through the ore layer. The influence of ore grain size on the degree of leaching and acid consumption was examined. The formation of gypsum on limestone results in the comminution of the initial raw material during leaching. The grain size of chalcopyrite was found to have no important influence on the leaching rate of copper. A higher consumption of sulphuric acid was found for the fractions (-3+1) mm, (?5+0) mm and (?5+3) mm than for the fractions (?10+5) mm, (?20+10) mm and (?20+0) mm. .

Leaching behaviour of rare earth elements from low-grade weathered crust elution-deposited rare earth ore using magnesium sulfate

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 505-514
Author(s):  
Kaihua Chen ◽  
Jiannan Pei ◽  
Shaohua Yin ◽  
Shiwei Li ◽  
Jinhui Peng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Magnesium Sulfate ◽  
Low Grade ◽  
Second Stage ◽  
Leaching Solution ◽  
Weathered Crust ◽  
Leaching Behaviour ◽  
N Pollution ◽  
Leaching Efficiency

ABSTRACTThe present study investigates the use of magnesium sulfate (MgSO4) instead of (NH4)2SO4 as a lixiviant in the recovery of rare earth elements (REEs) from clays. Experiments were carried out to investigate the influence of leaching conditions such as leaching time, lixiviant concentration and liquid:solid ratio on the leaching efficiency. The optimum leaching conditions, leading to 75.48% of total REE leaching efficiency, required a stirring speed of 500 rpm, a leaching time of 30 min, a lixiviant concentration of 3 wt.% and a liquid:solid ratio of 3:1. After extension of the leaching process by a second stage, the leaching efficiency may reach up to 96.19%, which is slightly higher than that obtained by (NH4)2SO4. Leaching varies from element to element, with Ce presenting the lowest leaching efficiency, and the partition in leaching solution is in agreement with that in raw ore other than for Ce. Based on these findings, MgSO4 lixiviant is an excellent alternative leaching agent for a sustainable REE industry because it reduces or eliminates NH4+–N pollution.

Clay mineral assemblages in British Lower Palaeozoic mudrocks

Clay Minerals ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 473-512 ◽  
Author(s):  
R. J. Merriman
Keyword(s):  
B Cell ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Hydrothermal Fluids ◽  
Low Grade ◽  
Lake District ◽  
Cell Dimensions ◽  
Mineral Assemblages ◽  
Lower Palaeozoic ◽  
Assemblage B

AbstractLower Palaeozoic rocks crop out extensively in Wales, the Lake District of northern England and the Southern Uplands of Scotland; they also form the subcrop concealed beneath the English Midlands and East Anglia. These mainly marine sedimentary rocks were deposited in basins created during plate tectonic assembly of the various terranes that amalgamated to form the British Isles, 400-600 Ma ago. Final amalgamation occurred during the late Lower Devonian Acadian Orogeny when the basins were uplifted and deformed, producing belts of cleaved, low-grade metasediments, so-called slate belts, with a predominantly Caledonian (NE-SW) trend. The clay mineralogy of mudrock lithologies - including mudstone, shale and slate - found in these belts is reviewed. Using X-ray diffraction data from the <2 μm fractions of ~4500 mudrocks samples, clay mineral assemblages are summarized and discussed in terms of diagenetic and low-grade metamorphic reactions, and the metapelitic grade indicated by the Kübler index of illite crystallinity.Two sequences of clay mineral assemblages, or regional assemblages, are recognized. Regional Assemblage A is characterized by a greater diversity of clay minerals in assemblages from all metapelitic grades. It includes K-rich, intermediate Na/K and Na-rich white micas, chlorite and minor amounts of pyrophyllite. Corrensite, rectorite and pyrophyllite are found in the clay assemblages of contact or hydrothermally altered mudstones. K-white micas are aluminous and phengite-poor, with b cell dimensions in the range 8.98-9.02 Å. Regional Assemblage B has fewer clay minerals in assemblages from a range of metapelitic grades. Phengite-rich K-mica is characteristic whereas Na- micas are rare, and absent in most assemblages; chlorite is present and minor corrensite occurs in mudrocks with mafic-rich detritus. Minor amounts of kaolinite are sporadically present, but dickite and nacrite are rare; pyrophyllite and rectorite are generally absent. The b cell dimensions of K-white mica in Regional Assemblage B are in the range 9.02-9.06 Å. The two regional assemblages are found in contrasting geotectonic settings. Regional Assemblage A is characteristic of the extensional basin settings of Wales, the northern Lake District and the Isle of Man. These basins have a history of early burial metamorphism associated with extension, and syn-burial or post-burial intrusive and extrusive volcanic activity. Intermediate Na/K mica probably developed from hydrothermal fluids generated around submarine volcanic centres. Deep diagenetic and low anchizonal clay mineral in these basins may develop a bedding-parallel microfabric. Chlorite-mica stacks also occur in the extensional basins and the stacking planes represent another type of bedding-parallel microfabric. Both types of microfabric are non-tectonic and developed by burial during the extensional phase of basin evolution. Regional Assemblage B is developed in the plate-convergent settings of the Southern Uplands and the southern Lake District. In the accretionary complex of the Southern Uplands the processes of burial diagenesis, metamorphism and tectonism were synchronous events. In both plate- convergent basins, low temperatures and tectonic fabric-formation had an important role in clay mineral reactions, whereas hydrothermal fluids played no part in clay genesis.

Complex permittivity and clay mineralogy of grain-size fractions in a wet silt soil

Geophysics ◽  
2008 ◽  
Vol 73 (3) ◽  
pp. J1-J13 ◽  
Author(s):  
Steven Arcone ◽  
Steven Grant ◽  
Ginger Boitnott ◽  
Benjamin Bostick
Keyword(s):  
Grain Size ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Complex Permittivity ◽  
Mineral Content ◽  
Size Fraction ◽  
Clay Mineralogy ◽  
Free Water ◽  
Size Fractions ◽  
Grain Size Fractions

We determined the complex permittivity and clay mineralogy of grain-size fractions in a wet silt soil. We used one clay-size fraction and three silt-size fractions, measured permittivity with low error from [Formula: see text] with time-domain spectroscopy, and estimated mineral weight percentages using X-ray diffraction (XRD). The volumetric water contents were near 30%, and the temperature was [Formula: see text]. For the whole soil, standard fractionation procedures yielded 2.4% clay-size particles by weight, but XRD showed that the phyllosilicate clay minerals kaolinite, illite, and smectite made up 17% and were significantly present in all fractions. Above approximately [Formula: see text], all real parts were similar. Below approximately [Formula: see text], the real and imaginary permittivities increased with decreasing grain size as frequency decreased, and the imaginary parts became dominated by direct-current conduction. Similarly, below approximately [Formula: see text], the measured permittivity of montmorillonite, a common smectite, dominated that of the other clay minerals. Total clay mineral and smectite mass fractions consistently increased with decreasing grain size. Below [Formula: see text], a model with progressively increasing amounts of water and parameters characteristic of montmorillonite matches the data well for all fractions, predicts permittivities characteristic of free water in smectite structural galleries, and shows that the similar real parts above [Formula: see text] are caused by a small suppression of the high-frequency static value of water permittivity by the smectite. We conclude that the clay mineral content, particularly smectite, appears to be responsible for permittivity variations between grain-size fractions. Small model mismatches in real permittivity near the low-frequency end and the greater fractions of kaolinite and illite suggest that the total clay mineral content might have been important for the coarser fractions.

scholarly journals Leaching Process of Weathered Crust Elution-Deposited Rare Earth Ore With Formate Salts

2020 ◽  
Vol 8 ◽  
Author(s):  
Zhuo Chen ◽  
Zhenyue Zhang ◽  
Ruan Chi
Keyword(s):  
Rare Earth ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Sodium Formate ◽  
Ammonium Formate ◽  
Swelling Ratio ◽  
Mineral Particles ◽  
Leaching Process ◽  
Weathered Crust ◽  
The Rare Earth

To strengthen the rare earth leaching process and weaken the hydration of clay minerals for preventing landslides, it is of great importance to adopt a green and sustainable leaching agent in the industry. In this work, the leaching process of weathered crust elution-deposited rare earth ores with formate salts (ammonium formate, potassium formate, and sodium formate) was investigated. The effects of formate salts on the linear swelling ratio and zeta potential of the clay minerals were studied. The experimental results showed that ammonium formate could effectively recover the rare earth elements from weathered crust elution-deposited rare earth as well as inhibit the leaching of impurity aluminum. At room temperature, when the ammonium formate concentration was 1% wt, the leaching efficiencies of rare earth and aluminum were 87 and 37%, respectively. Compared with traditional inorganic ammonium salts, the inhibition effect of impurity aluminum was obvious. In addition, the results of the linear swelling ratio in the clay minerals showed that the inhibit ability of formate salts on the hydration of clay minerals enhanced with the increase of the formate concentration, and the order of the inhabitation on the clay minerals followed: 1% ammonium formate &gt; 1.5% potassium formate &gt; 2.5% sodium formate &gt; distilled water. Based on the double layer theory, ammonium formate and potassium formate could effectively compress clay mineral particles to avoid water intake, which could increase the interaction between clay mineral particles and greatly reduce the electronegative property of the clay minerals, so as to effectively reduce the surface hydration of clay minerals to decrease the swelling of rare earth ore. The results of this experiment have important and practical significance in guiding the prevention of landslides, promoting the in-situ leaching technology, and effectively protecting the ecological environment in mining areas.

scholarly journals Animal-sediment interactions: the effect of ingestion and excretion by worms on mineralogy

2004 ◽  
Vol 1 (1) ◽  
pp. 533-559 ◽  
Author(s):  
S. J. Needham ◽  
R. H. Worden ◽  
D. McIlroy
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Lumbricus Terrestris ◽  
Depositional Environments ◽  
Mineral Dissolution ◽  
Combined Processes ◽  
Accelerated Weathering ◽  
Low Grade ◽  
Fine Grained ◽  
Peak Broadening

Abstract. By controlled experiments that simulate marine depositional environments, it is shown that accelerated weathering and clay mineral authigenesis occur during the combined process of ingestion, digestion and excretion of fine-grained sediment by two species of annelid worms. Previously characterized synthetic mud was created using finely ground, low-grade metamorphic slate (temperature approximately 300°C) containing highly crystalline chlorite and muscovite. This was added to experiment and control tanks along with clean, wind-blown sand. Faecal casts were collected at regular intervals from the experimental tanks and, less frequently, from the control tanks. Over a period of many months the synthetic mud (slate) proved to be unchanged in the control tanks, but was significantly different in faecal casts from the experimental tanks that contained the worms Arenicola marina and Lumbricus terrestris. Chlorite was preferentially destroyed during digestion in the gut of A. marina. Both chlorite and muscovite underwent XRD peak broadening with a skew developing towards higher lattice spacing, characteristic of smectite formation. A neoformed Fe-Mg-rich clay mineral (possibly berthierine) and as-yet undefined clay minerals with very high d-spacing were detected in both A. marina and L. terrestris cast samples. We postulate that a combination of the low pH and bacteria-rich microenvironment in the guts of annelid worms may radically accelerate mineral dissolution and clay mineral precipitation processes during digestion. These results show that macrobiotic activity significantly accelerates weathering and mineral degradation as well as mineral authigenesis. The combined processes of sediment ingestion and digestion thus lead to early diagenetic growth of clay minerals in clastic sediments.

scholarly journals Effect of Rare Earth on Microstructure and Wear Resistance of In-Situ-Synthesized Mo2FeB2 Ceramics-Reinforced Fe-Based Cladding

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3633
Author(s):  
Jun Jin ◽  
Junsheng Sun ◽  
Weimin Wang ◽  
Jijun Song ◽  
Hu Xu
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Rare Earth ◽  
Phase Composition ◽  
Sintered Sample ◽  
Area Fraction ◽  
Grain Refining ◽  
Grain Sizes ◽  
Carbon Arc

Mo2FeB2 ceramics-reinforced Fe-based cladding with various rare earth (RE) concentrations were prepared by the carbon arc surfacing process. The effects of RE content on the microstructure, phase composition, hardness and wear resistance of the cladding were systematically discussed. Meanwhile, the area fraction and grain size of Mo2FeB2 phase were exactly measured. Moreover, the refining mechanism of rare earth Y was analyzed. Results revealed that the claddings consisted of Mo2FeB2, FeCr, MoB and CrB. Adding the rare-earth Y decreased the grain sizes of Mo2FeB2 phase. Furthermore, grain-refining effects of Mo2FeB2 phase were significant when the RE content was 2% and hard phases evenly distributed in the cladding. In addition, the maximum microhardness value of claddings was about 1078 HV. The claddings with 2% RE contents had better wear resistance, which was equivalent to a sintered sample.

scholarly journals Animal-sediment interactions: the effect of ingestion and excretion by worms on mineralogy

2004 ◽  
Vol 1 (2) ◽  
pp. 113-121 ◽  
Author(s):  
S. J. Needham ◽  
R. H. Worden ◽  
D. McIlroy
Keyword(s):  
Clay Minerals ◽  
Clay Mineral ◽  
Lumbricus Terrestris ◽  
Depositional Environments ◽  
Mineral Dissolution ◽  
Combined Processes ◽  
Accelerated Weathering ◽  
Low Grade ◽  
Fine Grained ◽  
Peak Broadening

Abstract. By controlled experiments that simulate marine depositional environments, it is shown that accelerated weathering and clay mineral authigenesis occur during the combined process of ingestion, digestion and excretion of fine-grained sediment by two species of annelid worms. Previously characterized synthetic mud was created using finely ground, low-grade metamorphic slate (temperature approximately 300°C) containing highly crystalline chlorite and muscovite. This was added to experiment and control tanks along with clean, wind-blown sand. Faecal casts were collected at regular intervals from the experimental tanks and, less frequently, from the control tanks. Over a period of many months the synthetic mud (slate) proved to be unchanged in the control tanks, but was significantly different in faecal casts from the experimental tanks that contained the worms Arenicola marina and Lumbricus terrestris. Chlorite was preferentially destroyed during digestion in the gut of A. marina. Both chlorite and muscovite underwent XRD peak broadening with a skew developing towards higher lattice spacing, characteristic of smectite formation. A neoformed Fe-Mg-rich clay mineral (possibly berthierine) and as-yet undefined clay minerals with very high d-spacing were detected in both A. marina and L. terrestris cast samples. We postulate that a combination of the low pH and bacteria-rich microenvironment in the guts of annelid worms may radically accelerate mineral dissolution and clay mineral precipitation processes during digestion. These results show that macrobiotic activity significantly accelerates weathering and mineral degradation as well as mineral authigenesis. The combined processes of sediment ingestion and digestion thus lead to early diagenetic growth of clay minerals in clastic sediments.

Low-grade evolution of clay minerals and organic matter in fault zones of the Hikurangi prism (New Zealand)

Clay Minerals ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 579-602 ◽  
Author(s):  
Tatiana Maison ◽  
Sébastien Potel ◽  
Pierre Malié ◽  
Rafael Ferreiro Mählmann ◽  
Frank Chanier ◽  
...  
Keyword(s):  
Organic Matter ◽  
New Zealand ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Structural Characteristics ◽  
Mineral Chemistry ◽  
Fault Zones ◽  
Low Grade ◽  
Pore Fluid Chemistry ◽  
Mineral Crystallinity

ABSTRACTClay minerals and organic matter occur frequently in fault zones. Their structural characteristics and their textural evolution are driven by several formation processes: (1) reaction by metasomatism from circulating fluids; (2)in situevolution by diagenesis; and (3) neoformation due to deformation catalysis. Clay-mineral chemistry and precipitated solid organic matter may be used as indicators of fluid circulation in fault zones and to determine the maximum temperatures in these zones. In the present study, clay-mineral and organic-matter analyses of two major fault zones – the Adams-Tinui and Whakataki faults, Wairarapa, North Island, New Zealand – were investigated. The two faults analysed correspond to the soles of large imbricated thrust sheets formed during the onset of subduction beneath the North Island of New Zealand. The mineralogy of both fault zones is composed mainly of quartz, feldspars, calcite, chabazite and clay minerals such as illite-muscovite, kaolinite, chlorite and mixed-layer minerals such as chlorite-smectite and illite-smectite. The diagenesis and very-low-grade metamorphism of the sedimentary rock is determined by gradual changes of clay mineral ‘crystallinity’ (illite, chlorite, kaolinite), the use of a chlorite geothermometer and the reflectance of organic matter. It is concluded here that: (1) the established thermal grade is diagenesis; (2) tectonic strains affect the clay mineral ‘crystallinity’ in the fault zone; (3) there is a strong correlation between temperature determined by chlorite geothermometry and organic-matter reflectance; and (4) the duration and depth of burial as well as the pore-fluid chemistry are important factors affecting clay-mineral formation.

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