Alkali Flux Research Articles

Early Islamic glass (7th- 10th centuries AD) in Unguja Ukuu, Zanzibar: A microcosm of a globalised industry in the early 'Abbasid period.

Eighty-two glass vessels, recovered from the excavations at the ancient Swahili settlement and port of Unguja Ukuu in Zanzibar, Eastern Africa, were analysed using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results show that all of the glass samples are soda-lime-silica glass. Fifteen glass vessels belong to the natron glass type and are characterised by low MgO and K2O (<1.50%), suggesting they were made from natron, a mineral flux that was widely used during the Roman period and Late Antiquity. Sixty-seven glass vessels belong to the plant ash glass type, characterised by high magnesia and potash levels (>1.50%), suggesting plant ash was the main alkali flux. Based on the major, minor and trace elements, three different compositional groups were identified for the natron glass and three were identified for the plant ash glass: (1) UU Natron Type 1, (2) UU Natron Type 2, (3) UU Natron Type 3, (4) UU Plant ash Type 1, (5) UU Plant ash Type 2 and (6) UU Plan ash Type 3. Comparison with contemporary Middle Eastern glass groups shows that UU Natron Types 1, 2 and 3 correspond to Egypt II high Na2O, Levantine I and Levantine II respectively, while UU Plant ash Type 1 matches closely with Samarra Group 2. UU Plant ash Types 2 and 3 have unique chemical fingerprints that do not match any of the contemporary plant ash glass groups, but their chemical compositions show some affinity with the old Sassanian plant ash glass, suggesting a possible Mesopotamian provenance. Combined with existing research on early Islamic glass, the authors reveal a complex trading network in the globalisation of Islamic glass, particularly involving glass corresponding to modern Iraq and Syria, in the 7th- 9th centuries AD.

Raman focal point on Roman Egyptian blue elucidates disordered cuprorivaite, green glass phase and trace compounds

The discussed comparative analyses of Roman Imperial pigment balls and fragmentary murals unearthed in the ancient cities of Aventicum and Augusta Raurica (Switzerland) by means of Raman microspectroscopy pertain to a predecessor study on trace compounds in Early Medieval Egyptian blue (St. Peter, Gratsch, South Tyrol, Northern Italy). The plethora of newly detected associated minerals of the raw materials surviving the synthesis procedure validate the use of quartz sand matching the composition of sediments transported by the Volturno river into the Gulf of Gaeta (Campania, Southern Italy) with a roasted sulphidic copper ore and a mixed-alkaline plant ash as fluxing agent. Thus, the results corroborate a monopolised pigment production site located in the northern Phlegrean Fields persisting over the first centuries A.D., this in line with statements of the antique Roman writers Vitruvius and Pliny the Elder and recent archaeological evidences. Beyond that, Raman spectra reveal through gradual peak shifts and changes of band width locally divergent process conditions and compositional inhomogeneities provoking crystal lattice disorder in the chromophoric cuprorivaite as well as the formation of a copper-bearing green glass phase, the latter probably in dependency of the concentration of alkali flux, notwithstanding that otherwise solid-state reactions predominate the synthesis.

Characterization of the Flux System: Lithium-Aluminum Silicate (Li)-Alkali Feldspars (Na,K); Magnesium (Mg) and Calcium (Ca)-Silicates.

In this paper, the system of natural mineral alkali fluxes used in typical mineral industry technologies was analyzed. The main objective was to lower the melting temperature of the flux systems. The research has shown that the best melting parameters in the Ca–Mg– (Li,Na,K) system were characterized by the composition: A-eutectic 20% and wollastonite 80%, and it was reached at temperature 1140 °C; in addition, this set had the widest melting interval. Selected thermal parameters of mineral flux systems were also calculated. The technological properties of mineral composites such as shrinkage and brightness were also analyzed.

Silicate Mineral Eutectics with Special Reference to Lithium.

In this paper, the system of natural mineral alkali fluxes used in typical mineral industry technologies was analyzed. The main objective was to reduce the melting temperature of the flux systems. Particular attention was paid to the properties of lithium aluminium silicates in terms of simplifying and accelerating the heat treatment process. In this area, an alkaline flux system involving lithium was analyzed. A basic flux system based on sodium potassium lithium aluminosilicates was analyzed; using naturally occurring raw materials such as spodumene, albite and orthoclase, an attempt was made to obtain the eutectic with the lowest melting point. Studies have shown that there are two eutectics in these systems, with about 30% spodumene content. The active influence of sodium feldspar was found.

Дорожній одяг нежорсткого типу з місцевих кам’яних матеріалів, укріплених шлаколужним в’яжучим

Abstract Introduction.Road pavement is one of the most material-intensive and expensive elements of the road. The quality and durability of the road as a whole depend on the type of road construction material and the method of its application. Considering the significant needs of the road industry in construction materials, there is a need to find effective materials, the use of which allows building the road pavement that can resist the loadings of modern vehicles during the standard service life of pavement. In order to minimize the cost of construction and the negative impact on the environment, it is advisable to use local stone materials, the use of which allows obtaining the efficient road structures on their basis, requires minimal transportation costs and contributes to environmental protection.Problem statement. On the territory of Ukraine there are many deposits of stone materials and products of their associated processing in the form of crushing screenings [1–5]. These materials can be used as the stone materials for pavement layers arrangement without reinforcing binders, also for improving of their properties by strengthening with various types of binders.For strengthening and improving the properties of stone materials can be used the following:–inorganic binders, which include cement, lime and slag alkaline binder;organic binders, which include bitumen, bituminous emulsions and foamed bitumen–complex binders in the form of combination of cement with bitumen, as well as cement with bitumen emulsion or foamed bitumen.Considering the growth of transport loadings on road structures, it is necessary to provide the use of reliable and durable structures, for the construction of which it can be used available domestic raw materials. Organic binders, which include bitumen imported to Ukraine, are quite expensive and their cost is constantly rising. One of the perspective ways for solving this problem is the use of slag alkaline binders and concretes on their basis in the road construction, using local stone materials of different genesis as aggregates.Purpose. The purpose is to study the possibility of obtaining effective slag alkaline concrete with use as a mineral aggregate the stone materials of different mineralogical composition and strength, suitable for non-rigid pavement layers arrangement, capable to operate under repeated short-term loadings.Materials and methods. The erupted and sedimentary rocks that most widespread in Ukraine were used for study, namely: organic-hemogenic limestones, quartzite-like sandstones and granite materials. Blast furnace granulated slag and soda alkali flux were used as binder components. The mechanical properties and physical and chemical processes that occurred during the slag alkaline hardening were studied, and the technological parameters and the features of preparation of such concretes were studied. The state of the contact zone between the slag alkaline stone binder and various aggregates was determined by a set of methods allowed studding the physical and mechanical characteristics of the contact zone (micro hardness) and determining the distribution of the concentration of basic chemical elements in the contact zone, the composition of new formations and its microstructure.Results. The possibility of obtaining of effective slag alkaline concrete on aggregates of different mineralogical composition and strength that are suitable for non-rigid pavement layers arrangement that are capable for operating under repeated cyclic loadings, was theoretically determined and experimentally confirmed.Keywords: slag alkaline concrete, limestone, granite, sandstone, blast furnace milled granulated

Process optimization for the synthesis of ceramsites in terms of mechanical strength and phosphate adsorption capacity

Red mud (RM), an industrial waste of bauxite refinery, shows great potential in adsorptive phosphate immobilization but granulation of RM enables the ease for field application. Red-mud-based ceramsites with 12 compositions that blended Korean red mud, American red mud, ocher, and bentonite were synthesized through firing process (600–1000 °C). The porosity, bulk density, mechanical strength, mineralogical composition, and phosphate adsorption capacity of granulated RM were characterized and analyzed. The crystallization of plagioclases, nepheline and gehlenite was observed in the ceramsites with high alkali flux content, which enhanced both porosity and phosphate adsorption capacity. The characteristics of the ceramsites without phase transition were highly correlated with porosity. The mechanical strength of ceramsites was governed by crack population, describable by the Weibull distribution model, and thus the maximal tensile stress correlated negatively with porosity. Results showed that 32 wt % of KRREM and USREM treated at 1000 and 900 °C, respectively, yielded the best performing ceramites in terms of mechanical strength and phosphate adsorption capacity. Ultimately, the phosphate adsorption capacity, as affected by initial phosphate concentration, contact time, and temperature, of the optimized ceramsites was studied.

A study of 11th–15th centuries AD glass beads from Mambrui, Kenya: An archaeological and chemical approach

Twenty-three 11th–15th centuries AD glass beads collected from the archaeological site of Mambrui in Kenya were analysed using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results show that all of the glass samples are soda-alumina-silica glass. They belong to the mineral soda- alumina (m-Na-Al) glass type, characterised by high alumina and relatively low calcium and magnesia contents, that was widely distributed in eastern and southern Africa and southeast Asia in the 5th century BCE – 19th century CE. They were made with a mineral alkali flux called reh and sand. Comparison with contemporary m-Na-Al glass beads from Africa and southeast Asia shows that all of the Mambrui glass beads share similar characteristics to m-Na-Al 6 glass. This new glass type was recently identified by Dussubieux and Wood (2020) and is characterised by elevated levels of U (avg. 60 ppm) and Cs (~1.5 ppm). It is commonly found in eastern African sites such as Manda and Gede in Kenya. The lead isotope results suggest that the Mambrui glass beads might have been coloured using lead sources from four different sources including ores from India and northern Thailand.

Whole-rock trace element analyses via LA-ICP-MS in glasses produced by sodium borate flux fusion

Abstract Trace elements provide crucial information about the origin and evolution of the Earth. One common issue regarding their analyses is the reduced analyte recovery during hot plate acid digestion for some geological samples. To overcome this, alkali fluxes (e.g., Lithium borate) have been used to produce an homogeneous synthetic glass that can be used then for both X-ray fluorescence (XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In this sense, we developed a method for LA-ICP-MS whole rock trace element analyses in glasses prepared by mixing high-purity sodium tetraborate and rock powders at high-temperature. We selected six international reference materials including peridotite (JP-1), basalt (BRP-1), kimberlite (SARM-39), pyroxenite (NIM-P), diorite (DR-N) and andesite (JA-1). Glasses were produced in a fully automatic fusion machine with step heating. Run products analyses were carried out on a Thermo® Element2 SF-ICP-MS coupled to a New Wave Research® Nd:YAG (213 nm) laser ablation system and on a Thermo® Element XR ICP-MS coupled to an Analyte G2 (193 nm) LA system. Results show that glasses are homogeneous and there is good agreement (generally > 90%) between our data and literature values for most trace elements, including large ion lithophile elements (LILE), high-field strength elements (HFSE) and rare-earth elements (REE).

NEW DATA ON THE TECHNOLOGY OF FAIENCE PRODUCTION IN CENTRAL EUROPE IN THE EARLY BRONZE AGE

New data on faience production technologies in central Europe come from an analysis of 12 faience beads from an Early Bronze Age cemetery in Poland. The beads were tested with the EPMA method. Altogether 65 measurements were made. In terms of morphology, the artifacts are all the same, but they differ in microstructure and chemical composition. For some a mixed alkali flux was used, for others soda‐rich plant ashes. Even so, all of the beads seem to have been made from local raw materials in central Europe (soda‐rich plant ashes could have come from plants growing near one of the mainland salt sources, which are frequent, for example, in south‐eastern Poland).

Extraction of rare earth elements from coal fly ash by alkali fusion–acid leaching: Mechanism analysis

ABSTRACT Coal fly ash (CFA) in some areas contains higher levels of rare earth elements (REEs), which can be seen as a potential substitute for rare earth resources. As an effective method of hydrometallurgy, alkali fusion has been widely used in the recovery of precious metals from secondary resources. In this study, taking a CFA sample and five REEs named Y, La, Ce, Pr, and Nd in the sample as objects, the mechanism of alkali fusion processes of CFA with different alkali fluxes (Na2CO3, NaCl, Na2O2, NaOH, KOH, and Ca(OH)2) was studied. The results showed that Na2CO3, Na2O2, NaOH, and KOH can destroy the structure of CFA to effectively improve the leaching efficiency of REEs from CFA. The total leaching efficiency of the five REEs can reach to 57.45%, 49.25%, 74.23%, and 64.93%, respectively, when these four alkalis were used as fluxs. In addition, with DSC analysis, the non-model fitting dynamics Kissinger method was used to calculate the kinetic parameters of alkali fusion reaction between CFA and Na2CO3. The calculated alkali fusion activation energy E was 895.52 kJ·mol−1, the pre-exponential factor A was 3.47 × 1041 min−1, and the reaction rate constant K was 1.68 min−1.

Using reference materials of blast furnace slag, steelmaking slag, converter slag and fused fluxes when developing a procedure for analysis of slag-forming mixtures using inductively coupled plasma atomic emission spectrometry

Introduction . Slag-forming mixtures play an important role in obtaining metal without non-metallic inclusions. Required properties of slag-forming mixtures (SFMs) directly depend on their chemical composition, that is why control of individual component content in a mixture is an important stage in the technological chain of metallurgical production. At the present time, it is a common practice to use inductively coupled plasma atomic emission spectrometry (ICP-AES for analyzing SFMs, requiring sample preparation by alloying with alkali fluxes, which makes it impossible to determine potassium and sodium oxides in a sample. That is why it is necessary to work out a procedure for simultaneous determination of calcium, silicon, magnesium, aluminium, potassium, and sodium oxides by the method of ICP-AES, which would include quantitative transferring of all components into a solution. For that purpose, it is suggested to use microwave digestion of samples in autoclaves. The purpose was to develop a procedure for simultaneous determination of specified components of SFMs using ICP-AES after transferring the sample into a solution in an autoclave under conditions of microwave heating, and to certify it reference materials of slag and fluxes. Materials and methods . Compositional analysis of slag-forming mixtures was conducted using an atomic emission spectrometer with inductively coupled plasma «iCAP 6500 Duo»; sample digestion was conducted with the use of the microwave system «ETHOS PLUS». The following brands of SFMs were chosen as research objects: Melubir 9563 and Accutherm ST-SP/235AL4D; AlsifluxGS-C7; SRCP015, SRCP173P. For calibrating the spectrometer and controlling correctness of determining the specified components, the following reference materials were used: reference materials of blast furnace slag, steelmaking slag, converter slag, and fused fluxes, which have close chemical composition. Research results . An ICP-AES analysis procedure has been developed for calibrating the spectrometer and controlling correctness of determining CaO, SiO2 , MgO, Al2 O3 , K2 O, Na2 O in reference materials of blast furnace slag, steelmaking slag, converter slag and fused fluxes, which allows to establish target components of SFMs quickly and reliably.

Influences of alkali fluxes on direct reduction of chromite for ferrochrome production

Influences of alkali fluxes on direct reduction of chromite for ferrochrome production

Determination of Total Sulfur and Sulfate Sulfur in Geological Materials of Rocks, Soils, and Sediments by ICP-OES After Sample Digestion Using Alkali Flux

Determination of Total Sulfur and Sulfate Sulfur in Geological Materials of Rocks, Soils, and Sediments by ICP-OES After Sample Digestion Using Alkali Flux

Kinetics of hydrochloric acid leaching of niobium from TiO2 residues

Production of TiO2 generates waste containing significant quantities of valuable metals which if recovered, could have a positive impact on the economics of TiO2 production and waste management. In this investigation, the kinetics of HCl leaching of niobium from TiO2 residues are studied. The complex mineralisation of niobium in its primary ores makes economic recovery very difficult, often demanding the use of chlorination, carbochlorination or fusion with alkali fluxes for breakdown of its mineral concentrates and upgrading before leaching in acid, usually hydrofluoric acid. The effects of parameters leaching temperature (25–90°C), HCl concentration (0.5–4M), stirring speed (100–500rpm) and solid–liquid ratio were determined in the experiments. A maximum niobium extraction rate >90% was achieved within 60min of leaching the residues in 4M HCl at 70°C. The kinetics analysis showed that the dissolution of niobium in HCl is governed by pore diffusion of the random pore model, with an activation energy of 16.8±1.2kJmol−1 Nb.

Fluorine distribution during thermal treatment of sulfuric acid leaching products of complex beryllium raw materials at JSC UMP

X-ray diffraction, infrared spectroscopy, thermogravimetry and mass spectrometry were employed to study the behavior and distribution of fluorine in sulfuric acid treatment of the melt of beryl-bertrandite-phenakite-fluorite concentrates with alkali fluxes. It was established that fluorine in a solid phase is predominantly present in the form of sodium and calcium fluorosilicates and in a gaseous phase it is evolved in the form of silicon tetrafluoride and fluorosulfonic acid.

Investigation of ancient Harappan faience through LA-ICP-AES and SR-μ CT

Faience (glazed quartz) production is one of the complex craft techniques used by artisans to create high-status goods for elite consumers during the Harappan Phase, 2600–1900 BC. In this study, some faience objects selected from Harappa site, Pakistan were analyzed by LA-ICP-AES and SR-μ CT. The results suggested that these faience objects can be divided into two groups by using different flux: sajji-khar (a kind of plant ash) and mixed alkali flux; copper and iron were used as coloring elements in the blue and red faience; the forming technology of two groups of faience was similar:these beads were firstly formed on an organic cylinder and then glazed by using the efflorescence technique according to replica experiments and the structural information revealed by SR-μ CT slices. Up to our knowledge, the results firstly and scientifically confirm that the production of the Harappan faience beads adopts the efflorescence glazing method. The research has increased the understanding about production technology of ancient Indus faience.

Development of undersized (12.5 mm diameter) low‐dilution glass beads for X‐ray fluorescence determination of 34 components in 200 mg of igneous rock for applications with geochemical and archeological silicic samples

A low‐dilution, undersized (12.5 mm diameter) glass–bead technique was developed for X‐ray fluorescence determination of 34 components (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Hf, W, and Pb) in precious silicic samples for geochemistry and archeology. This preparation was consolidated based on the properties of the specimen, including disk formability and detachability from a small crucible, through variation of the amounts of the two samples (basaltic and granitic rocks) and releasing reagent. The specimen was prepared by fusing a mixture of 200 mg of powdered sample, 200 mg of lithium tetraborate as a flux, and 60 µl of 18.42 mass% lithium chloride solution as a releasing agent in a small platinum crucible. Calibration curves were drawn using synthetic calibration standards, which were prepared by compounding chemical reagents, such as oxides, carbonates, and diphosphates containing analytes. The calibration curves showed good linearity with correlation coefficient values greater than 0.990. Using the proposed method, we determined 34 components in five igneous rock reference samples. The results were in agreement with the recommended values, accounting for uncertainties. With this method, preparation requires only small amounts of the powdered sample and alkali flux; however, still allowing for determination of many analytes, which is advantageous when dealing with limited quantities of precious samples. The present method has potential applications in the chemical characterization of various geological and archeological samples. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Composition and colouring agents of historical Islamic glazes measured with EPMA and μ-XRD2

Glazes from tiles of representative historic Islamic buildings and tableware ceramic from Central Asia, the Middle East, Asia Minor and North Africa were analysed by electron probe microanalysis (EPMA) and two-dimensional micro-X-ray powder diffraction (μ-XRD 2 ). From major element compositions, three main glaze types were identified: alkali, alkali–lead and lead glazes. Quartz frit and clay ceramics form the substrates of the glazes. A slight influence of the ceramic on the glaze compositions can be found for SiO 2 , Al 2 O 3 and K 2 O, but only for quartz frit substrates. PbO and/or alkali oxides were used as fluxes. Na 2 O is the dominant oxide in the alkali flux. MgO and P 2 O 5 are the decisive components for the discrimination between mineral soda and plant ash as a source of the alkali flux. The use of plant ash beside the established mineral soda as flux for the glazes was introduced during the 13 th century in Iran, latest during the 13 th /14 th century in Afghanistan, and during the 14 th /15 th century in Uzbekistan. Hence, a change of the flux happened later for the glazes than for local glass of the same regions. Lead-glaze compositions occur in almost all considered epochs and locations. Colouring ions are Co 2+ (blue), Cu 2+ (green in a Pb-rich matrix), Fe 3+ and Mn 4+ (brown/black) and Mn 3+ (violet). Pigments, such as SnO 2 , SiO 2 and PbSiO 4 , are whitening agents; Pb 2 Sn 2 O 6 was used for yellow colours. Iron-containing clinopyroxenes and Cu-Cr-Mn-oxides are found in black glazes.

PVA–PSSS membranes for alkali recovery through diffusion dialysis: effect of alkoxysilanes

Poly(sodium-p-styrene-sulfonate) (PSSS) is synthesized by the method of ARGET ATRP, then mixed with polyvinyl alcohol (PVA), and cross-linked with different alkoxysilanes, that is, tetraethoxysilane (TEOS), 3-aminopropyltriethoxysilane (APTS), or γ-glycidoxypropyltrimethoxysilane (GPTS). The obtained flexible cation-exchange membranes have water uptakes (WR) of 46.8–120.7% and ion-exchange capacities (IEC) of 1.03–1.64 mmol/g. The category of the alkoxysilanes strongly influences the membrane properties. The membrane from GPTS has the highest thermal stability with Td (temperature at 5% weight loss) of 267.4°C, the highest IEC, and the lowest swelling degree in 65°C water, which is due to the dual cross-linking of Si–O–Si and C–O–C between GPTS and PVA. When applied for diffusion dialysis (DD) process of NaOH/Na2WO4 mixture, the membranes exhibit excellent alkali flux. The OH− dialysis coefficients (UOH) are in the range of 0.0072–0.0208 m/h, higher than PVA blank membrane (0.0077 m/h) or commercial poly(2,6-dimethyl-1,4-phenylene oxide)-based membrane (0.004 m/h) (Tianwei Membrane Co., Ltd., Shandong of China). The separation factors (S) are in the range of 16.8–25.7, higher than PVA–PSSS membrane cross-linked with formaldehyde (S = 8.0). Hence, the membranes can be potentially applied in DD process for alkali recovery.

Egyptian faience glazing by the cementation method part 2: cattle dung ash as a possible source of alkali flux

Based on our current awareness, there are three distinct primary sources of alkali flux in the ancient Egyptian faience making: natron, soda rich plant ash and the so-called ‘mixed alkali fluxes’. Whereas the nature and origin of the first two types are identified to some extent, there are more questions regarding mixed alkali fluxes. In an attempt to provide further clarification on the latter source, a series of replication experiments on the production of Egyptian faience by the cementation glazing method were conducted using cattle dung ash as the source of alkali flux. After firing at 980 °C, the appearance of the faience objects, the microstructure and the chemical composition of selected samples obtained using scanning electron microscopy/energy-dispersive spectroscopy (SEM-EDS) were investigated. The discussion has primarily focused on cattle dung ash as the most, or one of the most, available sources of ash in ancient societies and its possible use as a source of alkali flux in the production of Egyptian faience, at least by the cementation glazing method.