Residual Solid Phase Research Articles

Relationship between ash fusion temperatures of ashes from hard coal, brown coal, and biomass and mineral phases under different atmospheres: A combined FactSage™ computational and network theoretical approach

A broad set of ashes originating from national and international sources of hard coal, brown coal, and biomass is investigated under different ashing temperatures (815°C and 450/550°C) as well as oxidizing and reducing atmosphere conditions. In this computational study the mineral phase composition is estimated and the respective masses are not taken into account, since these approaches have been regularly less successful. The resulting mineral phases are assigned to main mineral groups and related to the experimentally determined ash fusion temperatures. On the one hand this relation is based on network theoretical considerations for the liquid slag and on the other it combines those with the fusion behavior of the residual solid mineral phases. Lowest ash fusion temperatures are addressed to the presence of low temperature melting mixtures of several mineral phases, which formed a very fragile network. Finally, the effects of different ashing temperatures and atmosphere conditions on the resulting mineral phases and respective ash fusion temperatures are studied.

Aluminium coagulants efficiency evaluation for natural water clarification

The results of studying the efficiency of coagulants based on aluminum compounds in the process of clarifying bentonite suspensions are given. It was found that in nature bentonite suspensions are precipitated very slowly, and the residual content of the solid phase in the clarified water is at 19mg/dm3 at the initial turbidity of 34 dm3. Processing of bentonite suspension by coagulant solutions based on aluminum compounds allows improving the result, but it cannot be considered satisfactory. Even with the coagulant dose of 50 dm3 (by ion Al3+) the volume of clarified water does not exceed 25 % of the original, and the residual solid phase concentration ranges from 1.6 to 19.2 dm3. The adjustment of pH cannot significantly influence the situation. Neither the amount of clarified water nor residual concentrations of the solid phase are significantly changed. This situation is typical for all investigated coagulants − aluminum chloride, GOHA 2/3, coagulant “Polvak-68”. It is quite evident that for clarifying bentonite suspensions it is necessary to use other coagulants or combine a simultaneous use of the coagulants with flocculants. Applying the methods, which do not use additional chemical agents can be another best way out.

Selection of acid for weak acid processing of wollastonite for mineralisation of CO2

Typically, mineral carbonation comprises aqueous phase reactions involving the dissolution of naturally occurring magnesium and calcium silicate rocks, such as olivine, serpentinites and wollastonite, followed by the precipitation of magnesium and calcium carbonate minerals. In this report, we evaluated the effect of formic, acetic and DL-lactic acids on the calcium-leaching process from wollastonite between 22°C and 80°C and at atmospheric pressure. OLI Analyzer Studio 3.0 predicted equilibrium conversions of calcium and its speciation in the aqueous phase. Additionally, we measured dissolution rates, for a constant pH system, as a function of temperature for the three organic acids. All experiments involved the reaction of 17±1μm (volume mean diameter) ground rock samples with the acids in a stirred batch reactor equipped with in situ pH measurements. Inductively coupled plasma-optical emission spectrometry (ICP-OES) analysed the concentration of calcium ions in the leaching medium while scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) examined the morphology and surface chemical composition of the residual solid phase from dissolution experiments. We estimated the maximum dissolution rates of wollastonite in the limit of low but achievable pH and in the absence of diffusion limitation in pores and cracks of the SiO2 skin. At 80°C, these rates correspond to 26(±7)×10−5, 14(±3)×10−5 and 17(±4)×10−5molm−2s−1 for formic, acetic and DL-lactic acids, respectively. The apparent activation energies amount to 11±3, 47±13 and 52±14kJmol−1 for dissolution in formic, acetic and DL-lactic acids, respectively. These values indicate the initial diffusion limitation in the film around wollastonite particles for formic acid, and kinetic limitation for acetic and DL-lactic acids. The rates of dissolution rapidly decline for acetic and DL-lactic acids, but remain high for formic acid. The findings are altogether indicative of high performance of formic acid for extraction of Ca2+ for storing CO2. Further experiments are needed to assess the recycling of formic acid to determine its overall suitability as a Ca2+ carrier for the weak acid process.

Analysis of products from pyrolysis of Brazilian sugar cane straw

The main objective of this work is to investigate the chemical composition of the volatile compounds produced during the pyrolysis of sugar cane straw (SCS). The pyrolysis was conducted in a vertical furnace using a quartz reactor at a temperature of 700°C (7g of SCS, heating rate of 60°C/min, flux of 1mLmin−1 of N2 and 5min of hold time at the final temperature). Pyrolysis products (solid residue and bio-oil) were analyzed. The original biomass and the residual solid phase were characterized by Thermogravimetric Analysis (TGA) and Infrared Spectroscopy (FTIR). The biomass showed a TGA profile similar to cellulose and, according to FTIR analysis, it was rich in oxygenated compounds. The FTIR analysis of solid residue indicated that it was composed mainly by silica. Comprehensive two dimensional gas chromatography with time of flight mass spectrometry detector (GC×GC/TOFMS) was applied in the identification and semi-quantification of main compounds in bio-oil, allowing the identification of 123 compounds, mainly oxygenated (acids, ethers, aldehydes, ketones and phenols) with a predominance of furfural and hexenoic acid. The GC×GC/TOFMS allowed a group type classification of the compounds and a spatial organization that facilitated the identification of the main compounds in the 2D diagram.

Extracting hydrocarbons from Huadian oil shale by sub-critical water

The possibility of extracting hydrocarbons from Huadian oil shale by sub-critical water was found in a stainless steel vessel. The effects of temperature and pressure on the extraction of hydrocarbons were studied. After extraction experiments, the residual solid, liquid and gas phase samples were collected and characterized, respectively. The extract yield could reach 7wt.% (ad) when the extraction of oil shale was conducted at 260°C for 2.5h with the pressure of 15MPa. The results of thermogravimetry (TG) showed that the weight loss of residual solid samples was much smaller than that of the original oil shale. It indicated that kerogen components had been decomposed partly by treatment with sub-critical water. Gas chromatography–mass spectrometry (GC–MS) analysis showed that there were more than 300 recognizable peaks in the extracting solution following processing at 330°C and 18MPa. Large amounts of high molecular weight hydrocarbons were gradually decompounded by the increase in types and levels of low molecular weight hydrocarbons, and polycyclic and heterocyclic compounds with the rising of pressure and temperature. These indicated that sub-critical water is capable of cracking kerogen into smaller hydrocarbon compounds at relatively low temperatures.

Formation processes of Bi-2212 films prepared on Ag( [formula omitted]) substrate by an atomization technique

We have studied in detail the growth of Bi-2212 ribbon-like thin film by melting Bi-2212 powders dispersed on flat, sputter-deposited Ag(0 0 1) films with order of tens of nm root-mean-square surface roughness. The formation processes of Bi-2212 ribbon-like thin films were studied by in situ high-temperature microscope observations. Because the powders melt incongruently, the liquid phase disperses with residual solid phases on the substrate. The residual solid phases act as the barrier for the melting phase to diffuse. Nearly monophasic Bi-2212 with excellent c-axis orientation in these thin films, proved by X-ray diffraction results, is the result of shortened diffusion length of the liquid phase. These techniques can be used especially to synthesize high quality Bi-based superconducting thin films for intrinsic Josephson junction devices.

Melting Systematics of Modally Variable, Compositionally Intermediate Peridotites and the Effects of Mineral Fertility

Piston-cylinder experiments were performed at 10 kbar to investigate for MORB generation involves low-pressure fractionation the near-solidus partial melting systematics of modally variable of magmas generated by polybaric melting of adiaperidotites. Starting materials consisted of compositionally interbatically upwelling mantle beneath mid-ocean spreading mediate (i.e. containing moderate incompatible element abundances) centers. Because the slope of the mantle adiabat is steeper minerals, separated from a spinel lherzolite xenolith from Mt. than that of the mantle solidus (McKenzie, 1984; McNoorat, SE Australia, and recombined to create five starting mixtures Kenzie & Bickle, 1988), a rising parcel of hot peridotite varying in their proportions of olivine, orthopyroxene, clinopyroxene will cross its solidus and begin to melt. The resulting (Cpx), and spinel. These modes match those of starting materials melt is buoyant relative to residual solid phases and can made with fertile (FER) minerals from a different xenolith, inrise faster than the upwelling solids once an intervestigated in a companion study. A layer of vitreous carbon spheres connected pathway develops. Isotopic and trace element provided a melt sink in the experiments. Solidus temperatures for evidence in MORBs and abyssal peridotites suggests that the five peridotites are similar and estimated to be >1260 ± this can occur at melt fractions (F ) as low as 0·001 (i.e. 10°C based on the zero-F (melt fraction) intercepts of F vs 0·1%) (Salters & Hart, 1989; Johnson et al., 1990). These temperature curves. Melt productivity (∂F/∂T) varies significantly melts aggregate throughout the melting column and are between the starting materials, but unlike the FER runs, the overall eventually emplaced as oceanic crust, with the solid melt productivity does not correlate with the initial Cpx abundance. residuum forming abyssal peridotite. Although the proThis suggests that the compositional fertility of Cpx plays a greater cesses occurring between the onset of melting and the role in determining F at a given temperature than simply its overall ultimate eruption of MORBs are too complex to simulate source abundance. Low-F glasses have elevated SiO2 and Na2O experimentally, data generated by equilibrium batch contents relative to average basalts, as high as >53·9 and partial melting experiments, like those presented here, >2·5 wt %, respectively, but are less enriched than in equivalent are integral to any attempt to model the process mathFER melts. ematically (e.g. Klein & Langmuir, 1987; McKenzie & Bickle, 1988; McKenzie, 1989; Niu & Batiza, 1991; Kinzler & Grove, 1992a, 1992b; Langmuir et al., 1992;

Strain partitioning during partial melting and crystallizing felsic magmas

The rheology of partly molten felsic systems changes dramatically during the onset of melting and through crystallization. Solid to liquid and liquid to solid transitions are not rheologically identical, contradicting the concept of a unique rheological critical melt percentage. We use four thresholds, separating the successive stages according to the melt fraction. For the melting transition: (1) the liquid percolation threshold connects the melt pockets at about 8% of melt, thus allowing local magma displacement at the metric scale; and (2) for greater melt percentages (20–25%), a melt escape threshold corresponds to the onset of transport over large distances of the melt and part of the residual solid phase, leading ultimately to granitic bodies. For the solidification transition: (3) the first formation of a rigid framework of crystals which can accumulate stress, although the melt can still flow, corresponds to the rigid percolation threshold (55% solids); and (4) the system becomes totally locked at about 72–75% solid, which corresponds to the particle locking threshold. The present paper focuses on strain partitioning induced by the coexistence of two contrasting rheological phases between these thresholds. On a variety of scales, non-coaxial deformation is preferentially accommodated by the lower-viscosity melt which increases the vorticity in the melt phase and reinforces asymmetries in the flow pattern. Strain partitioning also increases the scale length of the weakest phase during melting and magma ascent, whereas strain partitioning decreases the scale length during crystallizing. Strain partitioning also affects the migration of melt, by raising the particle locking threshold and lowering the melt escape threshold. For three-dimensional deformations, such as transpression, the direction of melt segregation (e.g. horizontal) may differ from the direction of melt migration (e.g. vertical).

Mechanism for atomization of vanadium in the pyrolytic graphite-coated furnace

The sequence of solid phase reactions preceding the thermal production of atomic V in the pyrolytic graphite-coated furnace has been studied. Residual solid phases left in the furnace after thermal conditioning for 3 s at 800–2700 K have been characterized by their reactivity with Cl 2 or by their X-ray powder diffraction patterns. The following sequence of reactions leading to atom formation is proposed: V 2O 5 → V 2O 3 → VO → VC → [V (1) ⇌ V (g)]+C.

Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite

Dissolution runs with four biogenic high magnesian calcites (HMC) of different magnesium content were conducted in distilled water saturated with 100% CO 2 and 3% CO 2 at 70°C and 35°C in order to study the mechanism of alteration of HMC to low magnesian calcite (LMC). The isotopic composition ( δ 13 C and δ 18 O) of the solutions (−30%. relative to PDB and +40%. relative to SMOW, respectively) was maintained far from isotopic equilibrium with respect to the dissolving carbonate. The isotopic composition and Mg content of the residual solid phase was monitored throughout the approach to stoichiometric saturation. For the coralline algae Goniolithon, heterogeneous and possibly incongruent dissolution occurred which reduced the Mg Ca mole ratio in the solid from 0.44 to 0.26. The alteration was accompanied by an apparent isotopic equilibration of up to 20% of the solid. Runs with two littoral foraminifera, Archaias and Sorites showed a decrease in the Mg Ca mole ratio from 0.18 to 0.14 in the solid and an apparent isotopic equilibration of up to 10%. These changes began to occur before the bulk solution became saturated with respect to LMC. On the other hand the echinoid Clypeaster dissolved homogeneously and congruently with much smaller changes in magnesium and stable isotope composition: from 0.16 to 0.14 in Mg Ca mole ratio and less than 5% apparent isotopic equilibration. All isotopic shifts were in the direction of equilibrium with the solution isotopic composition. No isotopic shifts were observed in runs with Iceland spar under identical conditions. Textural differences in microstructure discovered by SEM examination of the HMC materials used suggest the possibility of an overall textural control over the observed differences in isotopic and chemical behaviour during the dissolution runs.

Investigation of the Hydrothermal Interaction of 99Tc-Doped Glass with Basalt Repository Nuclear Waste Package Components

AbstractHydrothermal experiments using basalt-repository nuclear waste package components have been carried out at 200°C and 30 MPa using 99Tc-doped PNL 76–68 waste glass. This work was conducted in support of the Basalt Waste Isolation Project. The experiments were carried out in rocking autoclaves that allowed for periodic solution sampling. Preliminary results that illustrated the effect of basalt on 99Tc solution behavior were discussed previously[l]. In this paper, we continue those observations by discussing the additional experiments that investigated the effects of steel. We also include the post-experiment solid phase analyses from all test configurations.The effect of steel on glass dissolution was observed to be minimal when basalt was not present, i.e., there were no discernible differences in the amount of glass dissolved (based on boron release), with or without steel present.The 99Tc solution concentration results showed that basalt, steel, and a combination of basalt and steel have an ability to dramatically lower the concentration of 99Tc in the solution, probably through a redox mechanism[2]. Solid run product analyses showed that without basalt present, a gel-like secondary phase consisting of an iron, zinc clay with an apparent smectite structure formed. When basalt was present clinoptilolite formed as the major secondary phase, due primarily to the presence of aluminum in the basalt mesostasis. Separation of the various solid run products and residual initial solid phases has not yet been achieved. Such a separation would facilitate the identification of the phase or phases with which 99Tc was associated. The solution results indicated that 99Tc, a potentially mobile radionuclide, may be incorporated in a relatively insoluble phase in the environment of a basalt repository. In addition, no synergistic effects between waste package components were observed that would increase the concentration of 99Tc in solution.

Evaporation metamorphism of primitive dust material in the early solar nebula

An evaporation experiment on matrix material of the Murchison (C2) meteorite up to 1900°C in vacuo has revealed the evaporation sequence of primitive dust material and the associated evolution of residual solid phases from hydrous silicates through magnesium silicates and iron-metal to calcium-aluminum oxides. The comparison with primitive meteorites suggests that the evaporation metamorphism coupled with the re-condensation may have played an important role in the generation of diverse primitive meteorites in the early solar nebula.