Siliceous Raw Materials Research Articles

Chert and obsidian procurement of three Corsican sites during the 6th and 5th millenniums BC

Provenance studies of Corsican siliceous raw materials used during, the Neolithic focused mainly on obsidian. They showed an almost systematic use of Monte Arci sources (Sardinia). Chert studies have long been dodged, whereas the multiplicity of potential origins, in Sardinia and in continental areas, may provide complementary spatial information about diffusion patterns and interaction phenomenon in the Middle Tyrrhenian during the Neolithic. We studied obsidian and chert industries of three Corsican sites: Renaghju (Early Neolithic), Monte Revincu and Vasculacciu (both Middle Neolithic). In order to assign a provenance, 2241 chert archaeological samples were characterized by petrographic approaches and 100 obsidian artefacts were submitted to geochemical analyses. Each site provides a specific trend regarding relative abundances of raw materials, provenance and consumption patterns. Considered in the wider perspective of the Neolithic Corsican context, results reveal procurement variations from a chronological as well as a geographical point of view. Those variations may echo economic and social evolutions undergone in Neolithic societies of the Tyrrhenian area.

Geochemical features of quartzites of the Karaul Mountain deposit (south quarry)

Results are presented for comprehensive study of the substance composition of quartzites with the aim of determining the content of micro-and macroimpurity components. Impurity distribution is studied for the first time in the main rock-forming, accessory and secondary minerals of conditioned raw material. Information is provided about the complete chemical composition, necessary for expanding the assortment of production from siliceous raw material.

Comparison of double-pulse and single-pulse laser-induced breakdown spectroscopy techniques in the analysis of powdered samples of silicate raw materials for the brick-and-tile industry

Single- and double-pulse laser-induced breakdown spectroscopy techniques applied to the analysis of pressed pellets of silicate raw materials were compared in terms of precision, sensitivity and limits of detection. Two Nd:YAG lasers (1064 and 532 mm) in an orthogonal configuration with a reheating arrangement have been employed. The main factors influencing system performance were optimized, i.e. laser pulse energies and interpulse separation. The behaviour of plasma temperature was studied over a period of time and calibration curves for Mg were constructed for both the single and double-pulse setup. When comparing the single- and double-pulse techniques, limits of detection of Si and Mg for the double-pulse technique were found to be 10 times lower.

Biological Purification of Silicate Minerals

Bioleaching is technology applicable to iron extraction from low-grade non-metallic raw materials. Bioleaching of quartz sands and feldspars involves the action of heterotrophic bacteria. Impurities include fine – grained limonite, goethite, hematite or mica were removed by the reductive dissolution of Fe3+ in linked with the silicate mineral destruction. Heterotrophic bacteria produced organic acids that are able to solubilize Fe oxide and silicates but require organic carbon as a source of energy. Molasses is a relatively inexpensive carbon source used for various industrial fermentations and contains also other nutrients that accounted for the enhancement of iron dissolution in this study. The admixture of pigments in molasses coloured the samples, but the discoloration could be removed by the addition of NaClO following the bioleaching step. The feasibility of the bioleaching treatment has to be tested specifically to each type of silicate raw materials. The Fe content in the quartz sands and feldspar samples by the biological leaching decreased as much as 60% and by subsequent using of electromagnetic separation of feldspars, the decrease of Fe content in 74% was achieved. However, the application of magnetic separation of quartz sands after bioleaching resulted in total iron removal of 93 % and in such combined way prepared product contained 0.024 % of Fe2O3. Achieved results on iron removal point to the fact that combination of leaching and magnetic separation enables to obtain product usable in glass and ceramic industry.

Development of Forsterite Refractories from Indian Olivine

Large amount of different magnesium silicate raw materials are available in the region of Karnataka and Tamilnadu, India, which did not get a wide commercial acceptance for the production of refractories even today. One such material is olivine, a by-product from the magnesite mines, which can be used for the manufacturing of forsterite refractories, a substitute for magnesite refractories in many applications. After chemical analysis of for sterite, compositional adjustment was done by adding dead burned magnesite to maximize the forsterite phase and to convert the impurities to high temperature compounds. Uniaxially pressed products of such compositions were sintered in the temperature range of 1200°—1600°C and characterized for various refractory properties.

From Lithics to Spatial and Social Organization: Interpreting the Lithic Distribution and Raw Material Composition at the Final Palaeolithic Site of Kettig (Central Rhineland, Germany)

During the Final Palaeolithic Federmessergruppen period, a wide range of siliceous raw materials was used in the Central Rhineland (Germany). Beside materials from the immediate region, exogenous resources such as flint from up to 100km away in the Meuse drainage area and the moraines of the Saalian glaciation were exploited. At Kettig, the spatial distribution of different lithic raw materials and analysis of several categories of burnt finds allow the characterization of the settled area in space and time. While adequate, good-quality raw material was available in the Central Rhineland, the regular use of exogenous raw materials at Central Rhineland sites also demonstrates the necessity of maintaining regular social contacts with other groups in neighbouring regions.

New clinker formation process by the fluidized bed kiln system

Clinkers produced by the new fluidized bed kiln are different from the commercial rotary kiln clinkers in the formation process and their characteristic qualities. In the granulating unit, the cluster of free CaO that originates in the coarse particles of limestone plays a role as a nucleus and the granulation by the adhesion of fine particles of raw materials follows. The melt phase made from siliceous raw materials encourages adhesion. Clinker minerals are almost completed to form in the granulating unit, and the consumption of free CaO and the grain growth of calcium silicate progresses in the sintering unit.

Determination of the zeolite and silicate content in detergent products by wavelength-dispersive x-ray fluorescence spectrometry

A method was developed for the determination of zeolite and silicate in detergent products and raw materials by wavelength-dispersive x-ray fluorescence (WDXRF) spectrometry. Al, Si and Na were measured after fusion of the sample with a mixture of lithium tetra- and metaborate. The influence of the fusion conditions, the stability of the glass beads and calibrations using practical and calculated α values were studied. The WDXRF method was validated by analysing laundry detergent products and zeolite and sodium silicate raw materials. The detection limit was 0.012% for Al, 0.010% for Si and 0.020% for Na (= 0.05% anhydrous zeolite and 0.08% sodium disilicate). The precision was dependent on the homogeneity of the sample. For Al, Si and Na in zeolite, the long-term precision was 0.08, 0.09 and 0.10%, respectively. For detergent powders, maximum relative standard deviations of 0.2, 0.3 and 0.7% were found for Al, Si and Na, respectively. No significant difference was found between the WDXRF method and the reference methods (titration, gravimetry, flame atomic absorption spectrometry). Copyright © 2000 John Wiley & Sons, Ltd.

Caractérisation des silex par l'analyse des microfaciès et application au peuplement préhistorique de l'Auvergne (France)

Microfacies analysis has been made on a sample of siliceous raw material from both natural deposits and archaeological sites from Auvergne. The objectives were twofold: to make precise mineralogical characterization and obtain new data on the geographical origin of archaeological flints. The results confirm the hypothesis on the foreign origin of the ‘silex blond’ (blond flint, Upper Cretaceous levels localized in the southern part of the Paris basin). In addition, the precise characterization of local flints enables the rectification of old denominations such as ‘jasper’ and demonstrates that these raw materials belong to the Upper Oligocene lacustrine or swampy levels.

Application de l'étude des inclusions fluides aux quartz taillés de quelques sites préhistoriques dans les Alpes du Nord

Quartz was used as siliceous raw material for recent periods of Prehistory. Its circulation path, from its crystallization area to the place where the knapped materials were found, is often quite questionable, specially concerning the quarry area. We have focussed our researches on the characterization of the quarz geographical source using a method yet poorly documented in Prehistoric studies : a characterization of the quartz through the study of the fluids trapped in the tinny fluid-inclusions inside the crystals. This two-sided approach is based on (i) cryometry, leading to the chemistry of the trapped fluid, and (ii) microthermometry, leading to the density (a fonction of the P-T entrapment conditions) of the fluid. This method has been tested on three Epipaleolithic to Neolithic sites of the Western Alps. Distincts peaks of homogeneization temperatures have been observed, depending of the site (higher temperatures in the Northernmost ones as to the Southernmore one). It's then possible to admit specific and different supply sources for the three sites, all of them located in the Alpine External Massifs.

Choosing the raw material for feeding SiO2 into uviol electrovacuum glasses

Methods of IR spectroscopy, optics, decrepitation, differential-thermal and x-ray analyses were used to investigate a siliceous raw material. It was shown that the use of milk-white quartz from the Taldy-Kurganskoe Deposit as a raw material for making uviol electrovacuum glasses is quite expedient, because it contains a small amount of mineral impurities, a large amount of gas and liquid inclusions, and provides for intense formation o f silicates.

Olivine rocks of the Topchulskoe Deposit in Kuznetsk Ala Tau

A brief mineralogical and petrographic characterization of ultrabasic mainly olivine rocks of the hyperbasic massif of Mount Konchik (Kuznetsk Ala Tau), collectively called the Topchulskoe Deposit of olivinites is presented. The mean chemical compositions of the main kinds of the serocks are calculated on the basis of more than 300 tests. It is shown that their composition completely corresponds to the industrial requirements on high-magnesia silicate raw materials. It is established experimentally that not only fresh olivinites and dunites but also their serpentinous variants, widely developed in the massif, can be used as a refractory magnesia material after an appropriate heat treatment. General information on some application domains for olivine raw materials in ferrous metallurgy and other industries is presented.

The Study of Drift in Inductively Coupled Plasma Optical Emission Spectrometry. Analysis of Silicate and Carbonate Raw Materials

The work shows the importance of maintaining a constant temperature in a spray chamber to obtain a stable signal in the ICP spectrometry of water solutions. Simple shielding against ICP thermal radiation and forced air circulation in a plasma torch/spry chamber. The internal standard method has been used to improve signal stability. The number and composition of calibration solutions have been optimized for the detremination of the main constituents of some silicate and carbonate raw materials. An ultrasonic cleaning bath has been successfully used instead of stirring to dissolve the samples after fusion with LiBO2. Certified Czech and Slovak geological reference materials and some international standards have been used to test the accuracy. Statistical tests have proved that the method of determination complies with the requirements of technological standards.

Synthesis of trioctahedral smectite from rice husk ash as agro-waste.

When rice husk is burnt, about 20 wt% of the husk remains as ash. The rice husk ash has more than 95 wt% of silica with high porosity and large surface area, because it still retains the skeleton of cellular structure. These properties of the rice husk ash can be used to synthesize siliceous raw materials such as clay minerals. Syntheses of smectite from the rice husk ash were conducted by using a starting material of a mixture of rice husk ash, magnesium chloride and lithium chloride with a molar ratio of Si: Mg: Li = 8: 5.34: 0.66. The optimal conditions of smectite synthesis is as follows

An Integrated Scheme for Rapid Analysis of Glass and other Silicate Materials without using Costly Platinum Wares and the Toxic KCN

An integrated scheme for chemical analysis of soda-lime-silica glass and a few other silicate raw materials, having the following significant features, has been developed.(a) Nickel and teflon wares have been introduced in the place of costly platinum articles; (b) interferences due to nickel as contaminant during fusion and silica from the matrix have been overcome by external addition of Al3+ as collector and O-phenanthroline as the masking agent; (c) use of toxic KCN which is invariably used in the common analytical processes has been done away with; and (d) the time and cost of an analysis have been drastically reduced.Following the developed scheme, samples of soda-lime glasses, clays etc have been analysed. The results show a satisfactory conformity with those obtained by standard methods.

Floor tiles based on siliceous raw materials

Floor tiles based on siliceous raw materials

Lining induction furnaces in Western Germany and other capitalist countries

The original materials for induction furnace crucibles in the Federal German Republic consist widely of siliceous raw materials mainly for melting cast iron and steel by the acid process. Cement quartzite containing 99% SiO2 is used for more responsible duties.

Studies on Mixed Portland Cements, IX

One of the present authors, S. Nagai, studied already on various mixed Portland cements and reported them (Journ. of Soc. Chem. Ind., Japan, 1929, 32, 343, 629, 838, 971, 1171; 1930, 33, 279, 601; 1931, 34, 461). The studies were further continued by the present authors and some results were preliminary reported in the present paper. The brief summany from the original Japanese report is abstracted as follows:(1) The natural siliceous raw material “Hakusan Kasanbai or Yokeihakudo” of tuff origin was mixed with clinker in various proportions and ground with gypsum by a laboratory ball mill.(2) The chemical composition of raw materials and the prepared Portland cement and mixed Portland cements are compared in the following table.(3) These cements have the following physical properties of specific gravity, fineness, voids, etc., which are shown with the mixing proportions of their raw materials in the following table.(4) The samples were tested on their strength of 1:3-cement-sand mortars by the method described in the specification of Japanese Engineering Standards for Portland cement and blast furnace cement (JES 28 and 29), and the following results were obtained.(5) The cement samples were also tested on the compressive strength of plastic mortar by the special small cylindrical test piece, which was proposed by the present author (S. Nagai: “Studies on cements by the plastic mortar of small cylindrical test piece”, Journ. Soc. Chem. Ind., Japan, 1929, 32, 635, 641; 1930, 33, 129, 290) and obtained the following results.These results by the plastic or wet mortars of high water cement ratio are better to discuss on the mixed Portland cements than those by the dry mortars adopted in specifications of all countries. The principles of this plastic mortar tests are nearly equal to those proposed by Prof. Ros: “Die zukuenftigen schweizerischen Normen fuer Bindemittel auf Grundlage von Untersuchungsergebnissen der E. M. P. A. der E dg. Tech. Hochschuele in Zuerich, Diskussionsberichte Nr, 1, Nr. 10 & Nr. 60” and Dr. G. Haegermann: “Die Pruefung plastischer Moertel”, Protokoll des Vereins Deutscher Portlandzement-Fabrikanten, Sept. 1929 and “Die Zementpruefung bei Anwendung von Moertel mit hochem Zementzusatz”, Reports of the New International Association for Testing Materials, 1931.These studies are now further being continued and will be reported hereafter.

Rancidity

The heat treatment of siliceous raw materials is one of the most ancient evidence of pyrotechnology in human history. In fact, the controlled heating of rocks to facilitate the production of lithic artefact has been proved in several contexts, even back to the Palaeolithic. The use of the heat treatment can be preliminarily assessed by eye inspection of the stone tools. However, the rock variability and possible surface alterations make uncertain the result of this simple macroscopic approach. Therefore, more reliable methods, based on archaeometric techniques, have been developed, in order to characterize structural modifications of rocks due to the heating process. These techniques may involve some limitations, as concerns the size of the sample and/or its preparation. In this paper, we show how density measurement, using the Archimedes balance, may provide a clear indication on the presence of heat-treated archaeological lithic artifacts. The method involves the construction of a reference master curve: density vs heat treatment temperature, of geological chert samples with the same provenance of the archaeological artifacts under investigation. The novel procedure has successfully been tested with some stone tools from La Vela Neolithic site (Trento - Italy), which had been previously proved to be heat-treated by means of infrared spectroscopy and scanning electron microscopy. In this regard, the “density method” turns out to be a cost-effective and fast non-destructive approach, particularly suited for a preliminary assessment of the heat treatment of large lithic assemblages.