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The extraction of copper from black shales associated with fine-grained and complex base metal ore mineralization traditionally using pyrometallurgy becomes increasingly uneconomic, because one of the most significant cost factors is the high energy consumption. Thus, energy-saving alternative mineral processing methods are to be considered to improve the metal recovery route economically and environmentally. In this study, a milled, organic carbon-rich black shale ore from the Sangerhausen mining district in central Germany has been pre-treated by ethanol prior to the froth flotation tests to gain a copper concentrate marked by an increased copper content and more efficient copper recovery. The flotation product (15.3% Cu) was used for biohydrometallurgically batch tests to extract copper and associated trace metals. SEM-based automated particle analyses on the comminuted black shale ore, flotation product as well as tailings, bioleaching residues and abiotic leaching residues were used to trace the recovery performance particularly of copper sulfides. The black shale ore is characterized by high contents of bornite (2.8 wt%) and chalcopyrite (1.3 wt%) associated with a high grade of pyrite (5.8 wt%). Considerable enrichments were achieved in the flotation product for bornite (20.7 wt%) and chalcopyrite (10.3 wt%) as well as for galena and sphalerite, while pyrite was successfully depressed in the tailings. Compared to abiotic chemical leaching, the bioleaching test of the bornite- and chalcopyrite-rich copper concentrate was particular efficient in the recovery of bornite and chalcocite. However, chalcopyrite was leached insufficiently in both, abiotic and microbial leaching tests, and presents a common component in the residues. [ABSTRACT FROM AUTHOR]

Fe(III) hydroxysulfate minerals are secondary minerals commonly found in acid mine drainage (AMD) sites and have a major impact on water and soil quality in these environments. While previous studies showed that the Fe(III) hydroxysulfate mineral transformation could be mediated by some bacterial strains under laboratory conditions, the role of indigenous microbial activity in Fe(III) hydroxysulfate mineral transformation in natural environment has received little attention. In this study, microcosms were constructed with AMD-affected river water and sediment from the Dabaoshan Mine that was either left unamended or enriched with nutrients (lactate, nitrogen, and phosphorus (LNP)) and biosynthetic minerals (schwertmannite or jarosite). The results show that microbial activity played a decisive role in the mineralogical transformation of schwertmannite/jarosite in the AMD-contaminated site when organic carbon was available. The accumulation of Fe(II) and sulfide in microcosms amended with LNP indicates that schwertmannite/jarosite transformation is mediated by microbial reduction. XRD, SEM and FTIR analyses suggest that schwertmannite was completely transformed to goethite in the Sch-LNP microcosms at the end of their incubation. Jarosite in the Jar-LNP microcosms was also transformed to goethite, but at a much slower rate than schwertmannite. Bacterial community analysis reveals that the stimulated indigenous bacteria promote the mineralogical transformation of schwertmannite/jarosite. Most of these bacteria, including Geobacter , Desulfosporosinus , Geothrix , Desulfurispora , Desulfovibrio , and Anaeromyxobacter , are known to reduce iron and/or sulfate. The mineralogical transformation of schwertmannite and jarosite exerts significant control on the geochemistry of AMD-contaminated systems. [ABSTRACT FROM AUTHOR]

This study presents the combined use of field mapping, remote sensing data analysis, mineralogy, spectroscopy and GIS techniques for the geological mapping of Antiparos Island. Antiparos is part of the Cyclades Blueschist Belt located in central Aegean, where gneisses, schists and Pliocene volcanic rocks occurred. During the extended field work, a number of volcanic rock samples were collected from the southern part of Antiparos. The sampling strategy was to collect samples from the primary as well as the altered rocks in specific areas in which they were previously located from the remote sensing data processing. In this study, high resolution satellite images have been carried out in order to detect, allocate and separate the different geological formations. Furthermore, the existing geological map was georeferenced and all the tectonic lines and boundaries were digitized. All these features were implemented in a Mobile Mapper CE GPS using Arcpad GIS and checked in situ. The collected samples were analyzed in the laboratory using various techniques including XRD, Petrographic Microscopy and SEM. The qualitative mineralogical analyses were conducted by using XRD. The study was supplemented by the petrographic observations providing a detailed characterization of rock textures. In addition, SEM study and SEM-EDS analyses of the samples were emphasized on the genetic relations of the minerals. The laboratory results revealed that specific corrections should be made in the previous geological map of Antiparos concerning the volcanic rocks, especially at the southern part of the island. A significant conclusion is that the rock described as volcanic in the previous map proved to be a fossiliferous limestone which includes micritic matrix of calcite with an insignificant amount of fossils. All the analogical and digital data and the results of the petrographic analysis were imported in a geodatabase specially designed for geological data. After the necessary topological control and corrections, the data were unified and processed in order to create the final layout at 1/25.000 scale. [ABSTRACT FROM AUTHOR]

Molybdenum is an essential element for life, with growing production due to a constantly expanding variety of industrial applications. The potentially harmful effects of Mo on the environment, and on human and ecosystem health, require knowledge of Mo behavior in mining-affected environments. Mo is usually present in trace amounts in ore deposits, but mining exploitation can lead to wastes with very high Mo concentrations (up to 4000 mg/kg Mo for tailings), as well as soil, sediments and water contamination in surrounding areas. In mine wastes, molybdenum is liberated from sulfide mineral oxidation and can be sorbed onto secondary Fe(III)-minerals surfaces (jarosite, schwertmannite, ferrihydrite) at moderately acidic waters, or taken up in secondary minerals such as powellite and wulfenite at neutral to alkaline pH. To date, no Mo-metabolising bacteria have been isolated from mine wastes. However, laboratory and in-situ experiments in other types of contaminated land have suggested that several Mo-reducing and -oxidising bacteria may be involved in the cycling of Mo in and from mine wastes, with good potential for bioremediation. Overall, a general lack of data is highlighted, emphasizing the need for further research on the contamination, geochemistry, bio-availability and microbial cycling of Mo in mining-affected environments to improve environmental management and remediation actions. [ABSTRACT FROM AUTHOR]

The authors present the results of chemical and mineralogical analyses of urban dusts collected in the spring seasons of 2015 and 2016 in three different parks of the Cracow agglomeration. The parks are located in the city centre, in the Nowa Huta industrial district and in a new housing development situated around 9 km west of the city centre. Mineralogical instrumental analyses included the SEM, FTIR and XRD methods and revealed that the dusts of Cracow are highly amorphous and contain significant amounts of hydrocarbons, whereas quartz, feldspars, kaolinite and gypsum are their crystalline phases. Chemical analyses were carried out using the ICP-MS method on aqua regia extracts of the starting samples. The contents of selected toxic elements are: As 5–123; Cd 1–14; Pb 56–258; Zn 486–1891 mg/kg and Fe 0.74–4.02 wt%. The health risk of these elements imposed on the residents of Cracow frequently visiting the three urban parks was assessed on the basis of the health quotient index HQ. At its values exceeding 1, adverse health effects are probable in humans. The HQ values calculated for As and Tl contained in the Cracow Park dusts in the case of adults are 3.42E−01 and 3.00E−01, respectively. They are significantly higher (one order of magnitude) in the case of children 3.19E+00 and 2.27E+00, respectively. [ABSTRACT FROM AUTHOR]

Atmospheric leaching (AL) of low-grade nickel laterite ores often produces leach liquor containing significant amounts of trivalent iron, aluminium and chromium ions. These impurities are normally removed by increasing the leach liquor pH to precipitate these metals before the recovery of nickel, cobalt and other metal values. This paper documents an investigation of the removal of iron, aluminium and chromium from both synthetic and real nickel laterite AL leach solutions using single- and multi-stage precipitation methods. Single-stage precipitation experiments performed using synthetic leach solutions containing Fe(III) + Ni(II) + Al(III), Fe(III) + Ni(II) + Cr(III), and Fe(III) + Ni(II) + Al(III) + Cr(III) showed that greater losses of nickel to solids occurred in the presence of aluminium and chromium. Increasing the pH value of the solution and the precipitation temperature favoured the removal of iron, aluminium and chromium, but at a cost of greater nickel losses. However, by carefully controlling pH and temperature using a multi-stage precipitation process, the iron, aluminium and chromium can be rejected effectively by precipitation with minimal nickel loss and desirable sludge properties. The optimum conditions for a multi-stage precipitation process were found to be pH 3.0 and 55 °C in the first stage and pH 3.0 and 85 °C in the second stage. Using this approach, as much as 95% iron and chromium together with more than 80% aluminium can be removed; the level of nickel loss to the solid can be reduced to below 1%. The sludge showed a fast settling rate of 5.05 m/h following the addition of a cationic flocculant. Similar satisfactory results were also obtained when performing this multi-stage precipitation procedure with real leach solutions. [ABSTRACT FROM AUTHOR]

In this paper, submicron spinel-containing calcium aluminate (SP-CA) cements were prepared at temperatures of 1200 °C (RA12), 1300 °C (RA13), and 1450 °C (RA14) using reactive alumina, magnesium hydroxide, and calcium carbonate as raw materials. The microstructural characteristics and high temperature properties of refractory castables bonded by SP-CA cement were investigated. The results indicated that the mineralogical compositions of SP-CA were spinel (MgAl 2 O 4 , MA) and CaAl 2 O 4 (CA). The spinel phases presented no definite borders or shapes, with average size ranging from 0.1 μm to 1.2 µm at different sintering temperatures. After heating alumina-spinel castables, the submicron spinel particles bonded with corundum and hibonite (CA 6 ) grains could strengthen the castable body. However, the large sized (< 88 µm) spinel did not form links between spinel and alumina in the castable with added preformed spinel (castable AS). Submicron spinel can decrease the pore sizes of refractory castables from 2 µm to 0.5 µm. Extended finite element method (XFEM) calculations showed that smaller pores prevent stress concentration and result in increased deformation with limited crack propagation. Hence, large numbers of 0.5 µm pores can act as crack-stoppers to improve the thermal shock resistance of castables with added SP-CA cements. Thermal shock resistance tests showed that R '''' of castable RA12 was 39.7 m, which is significantly higher than that of castable AS (19.8 m). The corrosion rate of castable RA12 was 5 mm 2 /min, which is significantly lower than that of castable AS (7.4 mm 2 /min). Small pore size and submicron spinel played relevant roles in corrosion behavior. [ABSTRACT FROM AUTHOR]

Tajikistan has abundant copper-tin resources. In this study, mineralogical analysis of copper-tin ores from the Mushiston deposit of Tajikistan indicates that tin mainly occurred in mushistonite, cassiterite, and stannite, while copper mainly occurred in mushistonite, malachite, azurite, and stannite. The total grades of tin (Sn) and copper (Cu) were 0.65% and 0.66%, respectively, and the dissemination size of copper-tin minerals ranged from 4 μm to over 200 μm. Coarse particles of copper-tin minerals were partially recovered by shaking table concentrators with a low recovery rate. Based on the mineralogical analysis, flotation recovery was used for the first time on the fine particles of copper-tin minerals, including mushistonite, from shaking table tailings. Single factor flotation experiments, open circuit flotation tests, and closed circuit flotation tests were performed to determine the optimized flotation conditions. Results indicated that benzohydroxamic acid (C6H5CONHOH) and lead nitrate could effectively recover the mushistonite, cooperating with other depressants. The final concentrate contained 13.28% Sn, with a recovery rate of 61.56%, and 18.51% Cu, with a recovery rate of 86.52%. This method proved effective for the exploitation and use of this type of copper-tin resource in Tajikistan. [ABSTRACT FROM AUTHOR]

Despite of significant efforts in the last decades towards utilization of steel slag in the construction industry, steel slag stockpiling and landfilling operations do not seem to be declining in steel-producing countries. Use of steel slag as a construction material requires understanding of its engineering properties and development of a methodology to address its swelling potential. This paper focuses on the results of a series of laboratory tests (grain-size analysis, X-ray diffraction, specific gravity, compaction, maximum and minimum dry unit weight, direct shear, and long-term swelling tests) performed on samples of electric-arc-furnace ladle (EAF(L)) steel slag to assess its potential to be used as a geo-material. Direct shear test results indicated that the EAF(L) steel slag exhibits comparable frictional properties to angular crushed sand. Based on the leachate concentration levels from TCLP analyses, the EAF(L) steel slag tested was classified as Type III Solid Waste. The long-term, one-dimensional (1D) swelling test results showed continued volumetric expansion even after more than 16 months of monitoring. Replacing 5–10% by weight of EAF (L) steel slag with Class C fly ash reduced the 1D swelling to negligible levels. [ABSTRACT FROM AUTHOR]

There are several metasomatic uranium deposits in the area around Mount Isa in Queensland, containing a total of 56,400 t of uranium. Many of these ores are refractory in nature, meaning that relatively high leach temperatures (> 75 °C) and reagent dosages (> 50 g/L H 2 SO 4 ) are needed to effectively extract the uranium from them. Also, these ores are hosted in alkaline rock which means that acid leaching is unlikely to be economical. While refractory uranium ores are not typically leached in alkaline media, previous work has shown that uranium can be extracted from brannerite in alkaline media, albeit slowly. The same leaching conditions previously shown to be effective for the extraction of uranium from brannerite were repeated with a sample of refractory uranium ore from a deposit near Mount Isa in north western Queensland. Mineralogical analysis with a Tescan Integrated Mineralogical Analyser (TIMA) showed that the uranium was present as brannerite (51%) and coffinite (49%). The ore was leached in sodium carbonate media for 24 h. Leach temperatures of 50, 70 and 90 °C, and sparging with oxygen, air and nitrogen were tested. The effect of adding ferricyanide chemical oxidant was also tested. Similar initial uranium extraction rates were observed for the Mount Isa uranium ore compared with Sierra Albarrana brannerite leached under the same conditions in earlier work. The final extractions were lower however, due to the fine-grained nature of the uranium mineralisation in the ore. TIMA analysis on a residue produced under the most intense set of leaching conditions (90 °C, O 2 sparged) showed that the extent of coffinite dissolution was greater than that of brannerite dissolution during leaching. Likewise, the TIMA analyses showed that the extent of apparent uranium liberation decreased during leaching, due to poorly liberated particles remaining undissolved. These results indicate that alkaline leaching could be a viable method for the processing of these long overlooked ores provided that the uranium is sufficiently liberated. [ABSTRACT FROM AUTHOR]

The new mineral roymillerite PbMg(SiAlO)(SiO)(BO)(CO)(OH)O, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn-Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2 V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, $${\text{CO}}_{3}^{2 - }$$ , $${\text{BO}}_{3}^{3 - }$$ , and OH groups. The chemical composition is (wt%; electron microprobe, HO and CO determined by gas chromatography, the content of BO derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, BO 0.50, AlO 0.74, CO 5.83, SiO 7.90, HO 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is PbMgMnFeBAlCSiHO. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P $$\bar{1}$$ , with a = 9.315(1), b = 9.316(1), c = 26.463(4) Å, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) Å. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg(OH)[(Si,Al)O] and I-blocks Pb(OH)O(CO)(BO,SiO). The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, −115, 1-15), 3.378 (14) (126, 216), 3.282 (16) (−2-15, −1-25), 3.185 (12) (−116, 1-16), 2.684 (16) (031, 301, 030, 300, 332, −109, 0-19, 1-18), 2.382 (11) (0.0.-11). Roymillerite is named to honor Dr. Roy McG. Miller for his important contributions to the knowledge of the geology of Namibia. [ABSTRACT FROM AUTHOR]

Paleoclimatic/environmental changes of northern Mongolia were investigated by chemical and mineralogical analyses of sediment cores from Lake Hovsgol and Lake Erhel back to 18.9 and 34.3 cal ka BP, respectively. The climate of this region was dry in the glacial period, and wet in the Holocene. Desalination of Lake Hovsgol occurred at 13.2–11.6 cal ka BP, i.e., during the transition from the late glacial to early Holocene. At the same time, ca. 12.82 cal ka BP, deposition in the Lake Erhel area changed from fluvial to lacustrine. Climate of northern Mongolia was humid during the late glacial to the early Holocene period (ca. 10.57–7.24 cal ka BP for the Hovsgol and from ca. 12.82 to 7–8 cal ka BP for the Erhel). This reconstruction differs from that for the more northern Lake Baikal region, which humidification continued from the last glacial period until mid-Holocene. This difference could be attributed to longer period of glacier melting and permafrost thawing around the Baikal and on its watershed, associated with increased summer insolation. [ABSTRACT FROM AUTHOR]

Acid-base accounting (ABA) is a static test used to evaluate pre-mining drainage quality of ores with interpretations based on a reference 3-data point model. The method is often complemented with a kinetic test to ensure certainty of results. The challenges associated with both methods compel companies to rely on only the ABA test, thereby compromising on the long-term drainage quality. This paper validates a proposed 4-data point model that was used to establish a 20% increase in the alkaline amendment of ores at the AngloGold Ashanti Obuasi Mine in Ghana. The validation was done using model limits, the robustness of coefficient of determination and model factor sequence variation. Acidification trends and mineralogical data evaluation of tailings were used to characterise pH buffer trends in mine drainage. The modified 4-data point model, which incorporates a vital kinetic test factor into the ABA model, provides a criterion for the adjustment of carbonate amendment value to improve acid neutralisation in the drainage; this would reduce (1) cost of experimentation, (2) turnaround time for analyses, (3) complexities associated with both test methods. From the XRD data, alunite and goethite are present in tailings to provide sustained pH buffering in drainage beyond the scope of the modified model, while the characterised pH buffer trend could be used for monitoring drainage quality. [ABSTRACT FROM AUTHOR]

The article presents the obtaining results of clinkers of sulfate resistant and road cement during the production tests process. The usage of man-made wastes such as lead slag, coal mining waste as well as clay component and additives. X-ray, chemical analyzes of starting materials, clinkers and obtained cements were carried out. The regularities of charge compositions, saturation coefficient, modules, burning regimes on chemical and mineralogical composition and quality of clinkers and cements, improvement of rotary kiln operation, reduction of greenhouse gas emissions and fuel consumption are established. Various methods of analysis were used, calculations of raw mixtures composition were carried out according to the program "Shikhta" (designed to calculate the raw mix and the mineralogical composition of the clinker for the production of Portland cement. The program was developed in the V.G. Shukhov Belgorod State Technical University, Russia) and "Calculation of raw mixtures or CRM" (designed to calculate the raw mix of clinker. The program was developed in the M. Auezov South-Kazakhstan State University, Kazakhstan). The strength of factory and experimental cements was tested after 3, 7 and 28 days and after steaming. [ABSTRACT FROM AUTHOR]

A thermodynamic model is developed for pyroxenes in the chemical (mineralogical) system CaMgSi2O6 (diopside, Di, 1) - CaTiAlSiO6 (grossmanite, Gr, 2) - CaMg1/2 Ti1/2AlSiO6 (alumino - buffonite, AlBf, 3) - CaAl2SiO6 (Calcium Aluminum Tschermaks, CATS, 4), aka fassaites. It is formulated for the assumptions of molecular mixing between AlBf and Di, Gr and CATS components, and that the reduction in configurational entropy resulting from short - range Al - Si ordering on tetrahedral sites may be described using, as a proxy, a long-range, convergent ordering parameter for ordering of Al and Si between A and B tetrahedral sites on the AlBf - free tetrahedral sublattice. Nine out of sixteen independent thermodynamic parameters are calibrated to be consistent with calorimetric measurements of Benisek and others (2007), spectroscopic and statistical mechanical constraints on tetrahedral Al - Si ordering in pyroxenes on the Di - CATS binary (Cohen, 1986; Vinograd, 2001; Warren and others, 2001), and phase equilibrium constraints on Di - AlBf miscibility gaps in the Di - AlBf - CATS ternary subsystem (Yang 1975, 1976). The remaining seven independent parameters (for Gr - bearing fassaites) are constrained to be consistent with the distribution of fassaite compositions in calcium - aluminum - rich inclusions in carbonaceous chondrites (CAIs), experimental determinations of fassaite single - phase regions produced at the extremely low oxygen fugacities prevailing during their primary condensation/crystallization (for example, Beckett, ms, 1986), and the assumption that secondary fassaites in Wark - Lovering rims enclosing CAIs were in local equilibrium with the outer surface layers of the earlier (canonical) AlBf - rich fassaites at their layer contacts at temperatures of around 1473 K (Wark and Lovering, 1982; Meeker and others, 1983; Murrell and Burnett, 1987; Ruzicka, 1997; Dyl and others, 2011). In this model there is a miscibility gap between Di-rich and AlBf-rich fassaites on the Di - AlBf join which displays only very limited extension into the fassaite tetrahedron. On the Di - AlBf - CATS face of this tetrahedron there is a second miscibility gap (upper buffonite gap, UBG) with 0.08 < X4fas < 0.22 and 0.06 < X4fas < 0.25 at 1505 and 1473 K. This gap is modestly ellipsoidal with its long axis roughly radial to AlBf and it is roughly symmetrically disposed between Di and AlBf at 1505 K. At 1473 K this gap extends to the AlBf - CATS binary, intersecting it at very low and intermediate X4fas, with most of its CATS - rich binode being metastable with respect to assemblages composed of the minerals melilite, spinel, anorthite, perovskite and CATS - poor fassaite. A third miscibility gap extends from the CATS-rich portion of the AlBf - CATS binary, and occupies most of the CATS - rich portion of this ternary at 1505 and 1473 K. It is metastable with respect to assemblages composed of melilite, spinel, anorthite, perovskite and hibonite, and, has a CATS - rich binode that is virtually coincident with the Di-CATS binary at high CATS contents, in accordance with compositions of metastable, virtually AlBf-free CATS-rich fassaites (kushiroites) found in hibonite ≈ grossite + fassaite spherules in CAIs (for example, Krot and others, 1999). Within the fassaite tetrahedron at 1473 K the UBG is rapidly destabilized with addition of the Gr component, diminishing in dimension and collapsing to a critical endpoint at X2fas < 0.06. With further increase in Ti(Al)-1 exchange potential, the third miscibility gap in Di - AlBf - CATS fassaites (where it is metastable) becomes less extensive, and, it separates into an interior gap and one emanating from the Gr - AlBf - CATS ternary at a Ti(Al)-1 exchange potential corresponding to a reference Gr - CATS fassaite with X2fas (=Xref2) ≈ 0.22. Both of these gaps continue to decrease in size with further increases in Ti(Al)-1 exchange potential, with the gap emanating from the Gr - AlBf - CATS ternary terminating there in a critical point at X2 ref ≈ 0.30. With further increase in Ti(Al)-1 exchange potential the more Di-rich gap continues to move toward the Di - Gr - CATS ternary until X2 ref ≈ 0.50. At higher Ti(Al)-1 exchange potentials there is complete miscibility in quaternary fassaites, except in the immediate vicinity of the Di - AlBf binary, and, at very high Ti(Al)-1 exchange potentials, in fassaites near the Di - Gr binary. Evaluating the Ti(Al)-1 exchange potentials at which the extensive gap that is metastable in the diopside - alumino - buffonite - CATS ternary subsystem becomes stable in the quaternary system at given temperatures awaits development of a comprehensive database for CAI fassaites and their associated minerals, particularly the solid solutions melilite and hibonite (for example, Waldbaum, 1973; Waldbaum and Woodhead, 1975; Doyle and others, 2014). The model for fassaite thermochemistry is used to develop a Ti3+ - Ti4+ fassaite oxygen cosmobarometer based on experimental constraints (for example, Beckett, ms, 1986). Values of oxygen fugacity calculated with this cosmobarometer for fassaites and melilites, judged by Grossman and others (2008) to be coeval in refractory CAIs from the Allende carbonaceous chondrite, are more than three orders of magnitude below that of a gas of solar composition. [ABSTRACT FROM AUTHOR]

This paper presents the mineralogical and geochemical compositions of coal benches and non-coal (carbonaceous rock benches, parting, roof and floor) samples from the No. 1 Coal in the Longtan Formation of the Permian-Lopingian epoch from the Shugentian Coalfield, eastern Yunnan Province, southwestern China. The coal is rich in Nb, Ta, Zr, and Hf, which were derived from the Kangdian Upland with the dominant compositions of the Emeishan basalt. The minerals identified in the samples include mixed-layer illite-smectite, kaolinite, quartz, siderite, and minor calcite, pyrite, anatase and ankerite. Albite and chamosite occur in the roof and floor samples. The parting sample (SGT1-2p) is characterized by abundant siderite (64.9%) and calcite (20.1%), and one carbonaceous rock sample SGT1-11 contained a large amount of pyrite (26.1%). Four factors were responsible for the geochemical and mineralogical compositions in the samples; namely, the terrigenous detrital materials transported from the Kangdian Upland, direct volcanic ash inputs, multi-stage inputs of hydrothermal fluids, and marine influences. The co-existence of siderite and pyrite was attributed to a continental-marine transitional environment. [ABSTRACT FROM AUTHOR]

Although CO 2 storage in deep saline aquifers is now accepted as a potential option for atmospheric CO 2 mitigation, the chemico-mineralogical property alterations in the aquifer formation associated with CO 2 /brine/rock mineral interactions, the corresponding influence on formation hydro-mechanical properties and the effect of rock mineral structure, are not yet fully understood. This study was therefore conducted to obtain a comprehensive understanding of the effect of long-term CO 2 exposure on the chemico-mineralogical structure and corresponding strength characteristics of saline aquifer rock formations using silicate cement (SS) and carbonate cement (CS) Hawkesbury sandstone samples collected from the Sydney basin. Sandstone samples were first reacted with brine+CO 2 under different injection pressures (both sub-critical (4, 6 MPa) and super-critical (8, 10 MPa)) under a constant temperature of 35 °C. A comprehensive chemico-mineralogical analysis (ICP-AES and XRD) was first conducted on both the rock mass pore fluid and the rock matrix over the saturation period of one year, giving special attention to the alteration of dominant rock minerals (quartz, calcite and kaolinite). The overall influence after 12 months of saturation with brine and CO 2 on the strength characteristics of the two types of sandstones (SS and CS) was then investigated and correlated with the chemico-mineralogical reaction, in order to understand the coupled process. According to the test results, compared to the silicate cement-dominant mineral structure (SS), the presence of a carbonate cement-dominant mineral structure (CS) in the aquifer rock formation creates more significant alterations in the formation's chemico-mineralogical structure upon CO 2 injection. This is because calcite mineral reactions occur at much greater rates compared to quartz mineral reactions in CO 2 -exposed environments. In addition, although some minor precipitation of kaolinite minerals may also occur upon CO 2 injection, the effect may not be significant. Overall, rock mineral changes in deep saline aquifers upon CO 2 injection have a significant influence on the strength characteristics of the reservoir rock mass, depending on the aquifer mineral structure, and CS formations are subject to much greater strength property changes upon exposure to CO 2 than SS formations. Interestingly, CO 2 injection causes a strength gain in SS sandstone and a strength reduction in CS sandstone. These mechanical property alterations in aquifer rock formations are also dependent on the CO 2 injection pressure and phase, and increasing the injecting CO 2 pressure significantly enhances the changes, due to the highly acidic environment created by the enhanced CO 2 solubility process. Changing the CO 2 phase from sub- to super-critical condition also accelerates the reaction mechanisms, due to the greater chemical potential of super-critical CO 2 . However, overall SS sandstone exhibits more stable chemical-mineralogical and mechanical characteristics upon CO 2 injection than CS sandstone, and exhibits more suitable characteristics for CO 2 sequestration. [ABSTRACT FROM AUTHOR]

Soundless cracking demolition agents (SCDAs) have emerged as a potential method for underground rock fragmentation. However, the application of SCDAs in deep earth formations requires them to be modified to suit each application. Basic understanding of the hydration mechanism and the expansive pressure generation of SCDAs is of paramount importance in the process of adapting SCDAs to such applications. Therefore, the microstructural, mineralogical and mechanical morphology of SCDA during the hydration process was studied through a series of experiments (Uniaxial compressive strength (UCS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis) carried out on SCDA specimens at different degrees of hydration. Experimental results suggest that mechanical properties of hydrating SCDA are dependent on the confinement provided to the SCDA during the hydration process and the porosity of aging SCDA reduce during hydration if the volume expansion is restrained. The pressure generation mechanism was explained using a spherical expansion model, and SEM images obtained for hydrating SCDA confirm this hypothesis. XRD analysis of SCDA indicates that expansive pressure is generated by a combination of Ca(OH) 2 and Ettringite formation in the system, although it is dominated by Ca(OH) 2 . The early strength gain in SCDA was found to be related to the calcium silicate hydrate formation in the compound. The relationships observed between the microstructure, mineralogy and the mechanical properties of SCDA with increasing expansive pressure aids to improve the current understanding of SCDA. [ABSTRACT FROM AUTHOR]

We present a summary of the mineralogy, mineral chemistry, and magnetic characteristics of all the five Bulgarian meteorite falls. We report the first mineralogical descriptions, chemical analyses, and magnetic measurements of the Konevo (1931) and Silistra (1917) meteorites. We classify Konevo as LL5, and Silistra as an ungrouped achondrite with HED affinities. Pavel (1966; previously classified as an H5) is reclassified as H3-anomalous. We also provide precise mineralogy and mineral chemistry of the Virba meteorite (1873, L6), and more details on the mineral chemistry of Gumoschnik (1904, H5). [ABSTRACT FROM AUTHOR]

The present study focuses on the Late Cretaceous Bidgol bauxite deposit in the Zagros Simply Fold Belt, SW Iran. The orebody is located in the eroded major NW–SE trending Koh-e-Hosseyn anticline and hosted as discontinuous stratified layers and lenses within the upper member of the Cenomanian–Turonian Sarvak Formation. Detailed mineralogical analysis reveals that diaspore, hematite, goethite, anatase, clinochlore, chamosite, and calcite are the major mineral components accompanied by minor amounts of detrital and REE-bearing minerals such as rutile, zircon and parisite. The ore texture suggest that the bauxite material has an authigenic origin but in some parts it has been transported short distances from a primary in situ environment and redeposited in karstic depressions. The spheroidal pisolites of the Bidgol bauxite formed under conditions of low water activity, favouring the formation of large diaspore cores and a single dry-to-wet climatic fluctuation. The mass change calculations relative to the immobile element Ti show that elements such as Si, Fe, Mg, K, Na and Sr are leached out of the weathered system; Al, Ni, Zr, Ga, Cr and Ba are concentrated in the residual system; and Hf, Ta, Co, Rb, Cs, Be, and U are relatively immobile during the bauxitisation processes. The Nb, Th, Y, V, Sc, Sn and ΣREE are relatively immobile in the initial stage of bauxitisation processes in the bauxite ores, but were slightly mobile at the later stage of bauxitisation. Geochemical data reveal progressive enrichment of the REE and intense LREE/HREE fractionation toward the lower parts of the bauxite profile. Cerium behaves differently from the other REEs (especially LREE) and show positive anomalies in the upper horizons that gradually become negative in the deeper parts of the profile. The distribution and fractionation of trace elements and REEs during the bauxitisation process in the Bidgol deposit are mainly controlled by the presence of REE-bearing minerals, fluctuations in soil solution pH, REE ionization potential and the presence of bicarbonates or organic matter. Geochemical analyses confirm a protolith contribution from the bedrock argillaceous limestone and suggest that the source material for the Bidgol bauxite was provided from a siliciclastic material derived from a continental margin. The mid-Turonian uplift led to the formation of karstic topography, rubbly breccia and a layer of ferruginous–argillaceous debris that was affected by lateritic weathering under humid tropical climate. Subsequently, mobile elements are removed from the profiles, while Al, Fe and Ti are enriched, resulting in the formation of the pristine bauxite materials. When the platform subsided into the water again, the pristine bauxitic materials were partly converted to bauxite. During the exposure of bauxite orebodies on the limbs and crests of anticlines and subsequent eroding and accumulation in the karstic depressions during folding and faulting in Oligocene–Miocene, important factors such as intensity of the weathering, drainage and floating flow may have improved the qualities of the bauxite ores. [ABSTRACT FROM AUTHOR]

The objective of this study was to produce lightweight expanded clay aggregates in laboratory and to evaluate their effect in lightweight concrete (LWC). The effect of clay type, mineralogical and chemical structures as well as treatment temperature were examined. After the production of aggregates, following a specific manufacturing process, their physical and microstructure properties were determined. Furthermore, the mechanical properties and the microstructure of LWC were studied. A durability study including water absorption and sorptivity, resistance to the chloride ions penetration, chemical attack and carbonation was conducted. In accordance with the guide for structural lightweight aggregate concrete (ACI 213R-03), the LWC was classified according to its unit weight with qc < 2000 kg/m3(LC 2.0) and compressive strength at the age of 28 days (LC16/20). Besides, it had the lowest chloride concentration penetration. The chloride penetration depth and the migration coefficient were lower than those of normal concrete. Its initial water absorption was slightly higher and the depth of carbonation was lower. Finally, the reduction of compressive strength, the weight change and the visual inspection after immersion in sodium chloride and nitric acid were an accelerated test procedure, which indicated the performance of concrete against chemical attack. [ABSTRACT FROM AUTHOR]

The Arch of Augustus in Susa (north-western Italy) was built in 9-8 bc by King Cottius, to celebrate the treaty between the Romans and the Gauls. It is made of white marble, which was considered for a long time to be locally extracted, but no archaeometric studies have been performed up to now. Therefore, a multi-analytical study based on petrographic (optical and scanning electron microscopy), electron microprobe and stable isotope analyses was carried out on the marble from the arch and from reference samples, with the aim of defining the provenance. All the data confirmed that white marble belonging to the metamorphosed carbonate cover of the Dora Maira Massif, known as Foresto marble, was used for the Susa Arch. This choice was probably made for economic reasons, but also due to the relative independence of the ruling family of the Alpes Cottiae, which was obviously interested in promoting a local marble. [ABSTRACT FROM AUTHOR]

In order to explore the link between comet 81P/Wild 2 and materials in primitive meteorites, seven particles 5 to 15 μm in diameter from comet 81P/Wild 2 have been analyzed for their oxygen isotope ratios using a secondary ion mass spectrometer. Most particles are single minerals consisting of olivine or pyroxene with Mg# higher than 85, which are relatively minor in 81P/Wild 2 particles (∼1/3 of the 16 O-poor cluster). Four particles extracted from Track 149 are 16 O-poor and show Δ 17 O ( = δ O 17 − 0.52 × δ O 18 ) values from −2‰ to +1‰, similar to previous studies, while one enstatite (En 99 ) particle shows lower Δ 17 O value of − 7 ± 4 ‰ ( 2 σ ) . This compositional range has not been reported among 16 O-poor particles in 81P/Wild 2, but is commonly observed among chondrules in carbonaceous chondrites and in particular in CR chondrites. The distribution in Δ 17 O indicates that 16 O-poor 81P/Wild 2 particles are most similar to chondrules (and their fragments) in the CR chondrites and Tagish Lake-like WIS91600 chondrite chondrule silicate grains, which indicates that they likely come from a reservoir with similar dust/ice ratios as CR chondrites and WIS91600. However, differences in the Mg# distribution imply that the 81P/Wild 2 reservoir was comparatively more oxidized, with a higher dust enrichment. Two nearly pure enstatite grains from track 172 are significantly enriched in 16 O, with δ 18 O values of − 51.2 ± 1.5 ‰ ( 2 σ ) and − 43.0 ± 1.3 ‰ ( 2 σ ) , respectively, and Δ 17 O values of − 22.3 ± 1.9 ‰ ( 2 σ ) and − 21.3 ± 2.3 ‰ ( 2 σ ) , respectively. They are the first 16 O-rich pyroxenes found among 81P/Wild 2 particles, with similar Δ 17 O values to those of 16 O-rich low-iron, manganese-enriched (LIME) olivine and CAI (calcium and aluminum-rich inclusions) – like particles from 81P/Wild 2. The major element and oxygen isotopic compositions of the pyroxenes are similar to those of enstatite in amoeboid olivine aggregates (AOAs) in primitive chondrites, in which 16 O-rich pyroxenes have previously been found, and thus suggest a condensation origin. [ABSTRACT FROM AUTHOR]

(Mg, Fe)O ferropericlase (Fp) is one of the important minerals comprising Earth's lower mantle, and its thermal conductivity could be strongly influenced by the iron content and its spin state. We examined the lattice thermal conductivity of (Mg, Fe)O Fp containing 19 mol% iron up to 111 GPa and 300 K by means of the pulsed light heating thermoreflectance technique in a diamond anvil cell. We confirmed a strong reduction in the lattice thermal conductivity of Fp due to iron substitution as reported in previous studies. Our results also show that iron spin crossover in Fp reduces its lattice thermal conductivity as well as its radiative conduction. We also measured the electrical conductivity of an identical Fp sample up to 140 GPa and 2730 K, and found that Fp remained an insulator throughout the experimental conditions, indicating the electronic thermal conduction in Fp is negligible. Because of the effects of strong iron impurity scattering and spin crossover, the total thermal conductivity of Fp at the core–mantle boundary conditions is much smaller than that of bridgmanite (Bdg). Our findings indicate that Bdg (and post-perovskite) is the best heat conductor in the Earth's lower mantle, and distribution of iron and its valence state among the lower mantle minerals are key factors to control the lower mantle thermal conductivity. [ABSTRACT FROM AUTHOR]

This study develop novel porous red mud (RM) based geopolymers and evaluates their potential to ensure prolonged pH control. Several properties of the novel geopolymers were examined including buffering ability, alkalis leaching behaviour, mineralogical composition, microstructure and physical properties. Two experimental plans were defined to evaluate the influence of porosity and RM content on those properties. The pH values of the eluted water and geopolymers OH − ions leaching have been determined over time showing that total OH − ions and the leaching rate can be tailored by controlling the geopolymers porous structure and the availability of free alkaline species. The lower pH gradient over 28th d (1.64 pH units) was achieved by combining a 0.025 wt% pore forming agent (aluminium powder) with 45 wt% MK replacement by red mud. A high and prolonged buffer capacity was accomplished, proving that red mud-based geopolymers have potential to be applied as pH buffering material. [ABSTRACT FROM AUTHOR]

Spectroscopy in planetary science often provides the only information regarding the compositional and mineralogical make up of planetary surfaces. The methods employed when curve fitting and modelling spectra can be confusing and difficult to visualize and comprehend. Researchers who are new to working with spectra may find inadequate help or documentation in the scientific literature or in the software packages available for curve fitting. This problem also extends to the parameterization of spectra and the dissemination of derived metrics. Often, when derived metrics are reported, such as band centres, the discussion of exactly how the metrics were derived, or if there was any systematic curve fitting performed, is not included. Herein we provide both recommendations and methods for curve fitting and explanations of the terms and methods used. Techniques to curve fit spectral data of various types are demonstrated using simple-to-understand mathematics and equations written to be used in Microsoft Excel® software, free of macros, in a cut-and-paste fashion that allows one to curve fit spectra in a reasonably user-friendly manner. The procedures use empirical curve fitting, include visualizations, and ameliorates many of the unknowns one may encounter when using black-box commercial software. The provided framework is a comprehensive record of the curve fitting parameters used, the derived metrics, and is intended to be an example of a format for dissemination when curve fitting data. [ABSTRACT FROM AUTHOR]

The Late Cretaceous Duwi Formation in Egypt overlies non-marine, varicolored shale of the middle Campanian Quseir Formation. It is conformably overlain by gray, laminated, foraminiferal-rich marine shale of the middle Maastrichtian Dakhla Formation. Detailed mineralogical and geochemical studies were carried out on the phosphate rocks of the Duwi Formation in Quseir-Safaga province (Geble Duwi Mine) to infer their source rocks, paleo-weathering and provenance of the sources. The importance of the effect of phosphate rock depends on the chemical form of phosphorus in which this element is combined. This information is important in the assessment of possible radiological hazards to human health; due to the presence of uranium in the apatite structure. The phosphatic rock materials may be used as building stones or as phosphatic fertilizers and animal feed ingredients. Mineralogically, they are composed mainly of apatite (fluor-apatite), calcite and quartz with minor amounts of pyrite. The studied Duwi phosphates are authigenic in origin, comparable to those of phosphatic nodules of Peru and Chile margins. They are most probably derived from pre-existing authigenic phosphorites. Provenance, they originate from reworked older sedimentary phosphorites and biogenic sources. The geochemical data, CIA values suggested that the Duwi Formation phosphates were subjected to low chemical weathering. Generally, the enrichment of the trace elements, REEs and uranium may have occurred during diagenesis. The studied phosphate samples were compared to the average of the Average World Phosphorite (AWP) and the Average Shale Composition (ASC). The major, trace and rare earth elements contents are compared with those in Egypt, North African, Asian and other localities. The ratios V/Cr, V/(V + Ni) and Mo/Al and the high concentrations of the redox sensitive elements revealed that the studied phosphates were deposited under anoxic reducing marine environments coupled with hydrothermal solutions, which is comparable to the environmental condition of the associated black shales. The concentration of the trace and toxic elements in the studied samples are considered to be below the limits for most field-grown crops. [ABSTRACT FROM AUTHOR]

The occurrence of hypoxia becomes more prevalent in coastal and marine waters due to ocean warming and human-induced eutrophication. While hypoxia is expected to hamper calcification via metabolic depression, recent studies showed that some calcifying organisms can maintain normal shell growth. The underlying mechanism is unclear, but may be associated with energy reallocation or mineralogical plasticity which reduces the energy demand for calcification. We tested the hypothesis that shell growth can be maintained under hypoxia by compromising the mechanical strength of shells as the trade-off, or changing the mineralogical properties of shells. The respiration rate, clearance rate, shell growth rate and shell properties of a calcifying polychaete (Hydroides diramphus) were determined under normoxia or hypoxia in two contexts (life-threatening and unthreatened conditions). Despite the reduced respiration rate and clearance rate under hypoxia, harder and stiffer shells were still produced at a higher rate under life-threatening conditions. The maintenance of this anti-predator response is possibly attributed to the reduced energy demand for calcification by altering mineralogical properties (e.g. increased calcite to aragonite ratio). Our findings suggest that this compensatory mechanism may enable calcifying organisms to maintain calcification under hypoxia and acclimate to the future metabolically stressful environment. [ABSTRACT FROM AUTHOR]

Ashes from fluidized bed combustion, i.e. FBC ashes, are not being practically used for the production of hydraulic binders. The problem is their chemical and mineralogical composition. FBC ashes are characterized by a higher content of SO 3 , highly active free CaO and sometimes higher loss on ignition. The higher proportion of these substances has resulted in volume and temperature instability. However, FBC ashes could be used within a certain limit concentration in binders with relatively similar chemical-mineralogical composition such as Portland cement. The potential use of FBC ash for the preparation of blended Portland cements was studied in this paper. For this purpose, two types of FBC ashes and one type of traditional fly ash were selected. The first representative was a filter FBC ash, the second one was a bed FBC ash. Fly ash from pulverized coal combustion was used for comparison. The samples were prepared by co-grinding of the selected ash, Portland clinker and gypsum in a laboratory ball mill to a given value of specific surface area. Ash content was 15% and 30% of the total sample weight. The samples were subjected to the determination of basic technological properties – the water/cement ratio, setting times, strength, and soundness. The course of the hydration process was monitored by the qualitative method of X-ray diffraction analysis (XRD). The hydration product quantification was performed by the thermogravimetric analysis (TGA/DTA). The amount of CaO attributable to Ca(OH) 2 and CaCO 3 was quantified. Based on the results, a conclusion was made that the utilization of FBC ash in blended Portland cement production is possible. The values of the physical-mechanical properties of the blended cements based on FBC ashes are similar to the reference. In the case of lower FBC ash content, they are even comparable with ordinary Portland cement. [ABSTRACT FROM AUTHOR]

This study is an attempt to identify the effective mix design and thermodynamic parameters for the moisture damage of hot mix asphalt. In the present study, 24 different combinations of asphalt mixtures were made and evaluated using three types of aggregates with different mineralogical composition, two types of asphalt binders, and three types of additives. The components of surface-free energy of asphalt binders and aggregates are measured to provide thermodynamic parameters using theWilhelmy Plate and Universal Sorption Device, respectively. To determine the performance of moisture sensitivity, environmental conditions simulation according to the modified Lottman test was used, and an indirect tensile strength test has been conducted on asphalt mixtures. The results of statistical analysis presented show that the free energy of cohesion, free energy of asphalt binder-aggregate adhesion, specific surface area of aggregates, and asphalt binder film thickness on the aggregate surface have a direct impact, and the debonding energy of the system and permeability of the asphalt mixture have a reverse impact on asphalt mixture strength against the moisture damage. [ABSTRACT FROM AUTHOR]

This study investigates petrophysical and acoustic properties of experimentally compacted reconstituted samples of seal sequences from the southwestern Barents Sea. The aggregates were collected from drill cuttings of mudstone and shale formations of two exploration wells, 7220/10-1 (Salina discovery) and 7122/7-3 (Goliat field). The washed and freeze-dried samples were characterized for grain size distributions, geochemical analyses, and mineralogical compositions. A total of 25 compaction tests (12 dry and 13 brine-saturated) were performed with a maximum effective vertical stress of 50 MPa. The laboratory measurements demonstrated that petrophysical and acoustic properties of argillaceous sediments can change within a sedimentary basin and even within a given formation. The results show that the collected aggregates from Goliat field are compacted more compared to Salina discovery. The maximum and minimum compaction are measured in samples collected from Snadd and Fuglen formations, respectively. The final porosity of brine-saturated specimens varies between 5% and 22%. The ultrasonic velocity measurements depict that samples with the same porosity values can have a broad range of velocity values. The resulting compaction trends in this study were compared to published compaction curves for synthetic mixtures of quartz and clay. All compaction trends show higher porosity reduction than the silt fraction with 100% quartz. Comparison of experimental compaction result of each mudstone and shale aggregate with its corresponding acquired well log data helps to delineate the burial history and exhumation in the study area. A net exhumation of 950 m and 800 m is estimated at Salina and Goliat wells, respectively. The outcomes of this study can provide insights for hydrocarbon prospect discovery in a pre-mature sedimentary basin in terms of exploration and production, and also for geological CO 2 storage sites. The experimental results may provide information for well log and seismic interpretation, basin modeling and seal integrity of investigated horizons. [ABSTRACT FROM AUTHOR]

Changes in mineralogical, chemical, and mechanical properties of a rock mass during the weathering process allow calibrating the degree of weathering. Based on those properties, various weathering indices can be used as tools for this purpose. This study focuses on using chemical weathering indices that represent the chemical behaviour of a rock mass and their relationship with other properties for better evaluation of weathering grades. Metamorphic rocks that undergo weathering due to both chemical and operational means at Smanalawewa hydropower station in Sri Lanka, where tropical climate exists, were selected for this study. Among the chemical weathering indices calculated, the product index, Ruxton ratio, silica-titania index, alumina-titania index, chemical weathering index by Sueoka, and S/SAF index change consistently with progressive weathering. They correlate well with the weathering potential index, Miura index, bulk density, and point load strength. Among the six indices mentioned, the product index, Ruxton ratio, silica-titania, and alumina-titania indices have been recognised as better measures to classify metamorphic rocks in Sri Lanka for chemical means. Since there is a good correlation with physical and mechanical properties, the chemical weathering index and S/SAF index also appear to be better indices in the same context. Weathering potential, Parker, and modified weathering potential indices, which are widely used, show minor fluctuations during weathering. On the contrary, the chemical index of weathering and chemical index of alteration fluctuate with progressive weathering. These changes exhibit the influence of bulk mineral composition of the rock, where aluminium rich minerals are present. This study clearly shows that chemical weathering indices of a particular rock mass are more reliable when they correlate well with physical and mechanical properties. [ABSTRACT FROM AUTHOR]

The platinum group elements (PGE), which are used in many high technology applications, are classified as critical metals by the EU. Therefore, research has to focus on potential alternative resources. Oxidized ores are found in the weathered zones of common sulfidic deposits, such as the Bushveld and the Great Dyke, and could be considered as potential future resources. The grades and reserves are high. However, due to geochemical and mineralogical changes induced by weathering, extraction of PGE is still limited and uneconomic. The current state of research on oxidized PGE ores in geosciences and processing is summarized. [ABSTRACT FROM AUTHOR]

AOD (argon oxygen decarburization) slag, which is the by-product of the stainless steel refining process, is a recyclable slag because of its high content of calcium and silicon. The leaching toxicity cannot be ignored in the recycling process because the slag contains a certain amount of Cr. In this study, the mineral analysis, batch leaching tests and thermodynamic and kinetic modeling by PHREEQC combined with FactSage software were performed to explore the influence of the dissolution of primary minerals and the precipitation of secondary minerals on the elution of Cr from AOD slag. The results indicated that the main minerals in the original AOD slag are larnite, merwinite, pyroxene and periclase. Cr was dispersed in the mineral phases mentioned above. The simulation of Cr leaching controlled by Cr(III)-hydroxide corresponded better to the batch leaching tests, while the Cr leaching controlled by chromite or double control was underestimated. Increasing the L/S ratio enhances the pH of the leachate and restrains the elution of Cr from the AOD slag. [ABSTRACT FROM AUTHOR]

At present, the dealkalization and comprehensive utilization of red mud is a worldwide problem. Studies on the settling performance and phase transformation of red mud by HCl, CaO, and HO leaching are limited. In this study, the characteristics of red mud were systematically analyzed. The average sizes of graded and initial red mud were 4.11 and 9.20 μm, respectively. X-ray diffraction (XRD), X-ray fluorescence spectra (XRF), and thermogravimetry-differential scanning calorimetry (TG-DSC) results indicated the different mineralogical phases, composition, and thermal behavior. The addition of HCl could neutralize the alkalization in the red mud slurry, and CaO could replace the Na and K. Notably, the pH of the red mud slurry had no obvious change with the increase in water washing times in a certain pH. Interestingly, soluble Al and Fe were not detected in the HCl-red mud and CaO-red mud. In addition, the settling ratio was used to express the settling performance of the red mud slurry. Their interaction mechanisms were proposed, which may include phase transformation and the changing of the size and surface area. The research provided a better understanding of the phase transformation and settling performance in the treatment of red mud by HCl, CaO, and HO leaching. [ABSTRACT FROM AUTHOR]

When finding the “sweet spot” of a shale gas reservoir, it is essential to estimate the brittleness index (BI) and total organic carbon (TOC) of the formation. Particularly, the BI is one of the key factors in determining the crack propagation and crushing efficiency for hydraulic fracturing. There are several methods for estimating the BI of a formation, but most of them are empirical equations that are specific to particular rock types. We estimated the mineralogical BI based on elemental capture spectroscopy (ECS) log and elastic BI based on well log data, and we propose a new method for predicting S-wave velocity (V S ) using mineralogical BI and elastic BI. The TOC is related to the gas content of shale gas reservoirs. Since it is difficult to perform core analysis for all intervals of shale gas reservoirs, we make empirical equations for the Horn River Basin, Canada, as well as TOC log using a linear relation between core-tested TOC and well log data. In addition, two empirical equations have been suggested for V S prediction based on density and gamma ray log used for TOC analysis. By applying the empirical equations proposed from the perspective of BI and TOC to another well log data and then comparing predicted V S log with real V S log, the validity of empirical equations suggested in this paper has been tested. [ABSTRACT FROM AUTHOR]

Detailed chemical and mineralogical analyses were conducted to characterize slag wastes, leachate, and associated tufa precipitates at an iron slag dump near Kraków in southern Poland. The slag contained elevated content of Cr (1,800-6,500 mg/kg), V (500-1,800 mg/kg), and Zn (up to 4,500 mg/kg). The negative environmental impact posed by the wastes can be potentially caused by the formation of leachate with extremely high pH (12.5-12.9), high sulphate (720 mg/l) and K concentrations (420-520 mg/l), and elevated concentrations of fluoride (1.7-2.1 mg/l) and Al (up to 2.7 mg/l). A dominant feature of the leachate was massive precipitation of calcareous tufa forming a cascade of tufa barrier ponds at the base of the slag dump. The tufa preferentially concentrated Pb, Sr, Ba, Rb, sulfur, and phosphorus, while Fe, Zn, Mg, Mn, Cr, and V were depleted relative to the content in the slag material. [ABSTRACT FROM AUTHOR]

Two kaolins from different geological areas of South Africa were compared as precursors for the synthesis of ZSM-5. Their effects on the formation of ZSM-5 and its physicochemical properties were investigated. The mineralogical phases, morphology, surface area and porosity characteristics, acidity and chemical nature of the synthesised materials were investigated using XRF, XRD, HRSEM-EDS, N 2 physisorption (BET) analyses, NH 3 -TPD and 27 Al/ 29 Si MAS NMR. The two kaolins differed in structural order and XRD showed Fishoek (SK) kaolin to be more crystalline than the Grahamstown (BK) kaolin with Stoch indices of 0.97 and 1.17 respectively. The more disordered BK resulted in a faster crystallisation of ZSM-5. ZSM-5 derived from the two kaolins showed a remarkable difference in its physicochemical properties as well. N 2 physisorption confirmed a well-developed microporous structure manifested from the slower crystallisation kinetics of SK. The slower dissolution of reactants in the gel also resulted in a difference in the chemical properties as a highly acidic ZSM-5 was derived from SK (1313 μmol) as compared to BK (633 μmol). 27 Al MAS NMR studies clearly confirmed the presence of highly reactive Al species in the synthesis gel of BK derived ZSM-5 correlating the enhanced crystallisation kinetics observed with the kaolin structural order and chemical reactivity. [ABSTRACT FROM AUTHOR]

Despite the technological improvements introduced in the production of ornamental granite, sludge is inevitably generated in end product cutting and polishing. The present study constitutes the first attempt to scientifically analyse granite sludge, focusing in particular on its characterisation and pozzolanic activity and the morphological and microstructural changes taking place in both thermally activated waste and in the pozzolan/Ca(OH) 2 system in the first 360 days of reaction. The possible valorisation of this waste as a component of more eco-friendly cements is assessed with a view to furthering the circular economy. The findings show that thermal activation has no beneficial effect on sludge pozzolanicity, which at later ages was similar to the activity observed in other additions such as copper and manganese silicate slag but lower than in silica fume, fly ash and fired clay materials. The granite waste/Ca(OH) 2 system microstructure, in turn, contains C-S-H gels characterised by a low (0.6–1.0) Ca/Si ratio. [ABSTRACT FROM AUTHOR]

Metacarbonates of the Moldanubian Zone (Bohemian Massif, Czech Republic) were studied to obtain qualitative and quantitative mineralogical-petrographic as well as stable isotopic data for the purpose of stone provenance studies, potentially applicable in material research studies of cultural heritage artefacts. Twenty-six samples from twelve different historical quarries, as well as two samples from historical artefacts, were analysed by both mineralogical-petrographic and geochemical methods including: polarizing microscopy, cathodoluminescence, scanning electron microscopy with microanalysis, petrographic image analysis, powder X-ray diffraction, and isotope ratio mass spectrometry. The petrographic characteristics allowed for the discrimination of groups of (1) calcitic marbles, (2) dolomitic marbles, and (3) carbonate-silicate rocks. These groups exhibit characteristic features such as (1) the presence/abundance of major rock-forming minerals, (2) grain geometric characteristics (specifically, mean carbonate grain size and index of grain size homogeneity), and (3) the presence of specific accessory phases. The content of non-carbonate minerals, some rock fabric parameters, as well as the carbon and oxygen isotope data exhibited significant variability, even within a single quarry in the case of some impure marbles and carbonate-silicate rocks. Although the carbon and oxygen isotopic ranges displayed overlaps among the quarries studied, the isotopic signatures throughout the Moldanubian Zone allowed for discrimination of a group of white calcitic marbles with high carbon and oxygen depletion, as well as white dolomite-calcitic marble with higher carbon isotope values when compared with other marble resources of the Bohemian Massif. A combination of the isotopic signature with detailed mineralogical-petrographic characteristics seems to provide sufficient information for discrimination of the Moldanubian marbles from one another. The provenance of the Vrchotovy Janovice artefact is very probably from the Rabí quarry, among the Moldanubian marbles. The provenance of the artefact from the Prague Klementinum was not definitively assigned; however, the Nehodiv quarry was considered its probable source locality. [ABSTRACT FROM AUTHOR]