Use of Mining Tailings or Their Sedimentation and Flotation Fractions in a Mixture with Soil to Produce Structural Ceramics

The ceramic materials industry has vast potential for use of waste from industrial processes, such as iron mining tailings. The aim of this study was to test technological use of tailings samples from the dam rupture of the Samarco S.A. Company in 2015 to produce structural ceramics. Sedimentation and flotation processes were used to improve their characteristics, analyzing their chemical and mineralogical composition and granulometry. We produced 48 samples with a mixture of soil and residues in proportions of 10, 20, and 30 wt%, with sintering at 950 °C. The results showed that co-processing of iron mining tailings can be considered viable for improving certain aspects of some technological properties. The maximum amount of residue used was 30 wt% for any of the fractions used, as above this concentration the specimens lose important characteristics.

Mineralogical Composition and Physical–Mechanical Properties of Dasht-E-Taatrang Zar Sand Deposits (Afghanistan)

Sand is a common construction material used for various purposes, e.g., concrete, mortar, render, screed, and asphalt. The usage depends on its fineness, and its fineness is controlled by its mineralogical composition and physical-mechanical properties. This research aims to determine the chemical and mineralogical composition and the physical-mechanical properties of the Dasht-e-Taatrang Zar sand deposits within the Qarabagh and Bagram districts of Kabul and Parwan provinces in Afghanistan. To achieve the objectives of this research, a review of the existing literature has been combined with new extensive field works for macroscopic studies and sample collection, and laboratory analyses. In total, 23 samples during two phases of field works were collected and subjected to lab works for XRF, Schlich, and XRD analysis to determine the chemical and mineralogical composition; moreover, sieve and Atterberg analysis, specific gravity, soundness, and alkali-silica reaction tests were performed for characterization of the physical-mechanical properties of the studied samples. The results of the tests show that the Taatrang Zar sand deposits are considered as a suitable construction material, and due to their simple accessibility, the deposits have high potential as a construction material supplier for the Kabul new city project (Dehsabz) in Kabul and adjacent Parwan and Kapisa provinces.

The use of natural clay-carbonate gypsum in the production of sulfate-containing cements

The purpose of the article is to study the raw materials located in the deposits of Kyrgyzstan and used in the production of sulfate-containing cements. The article aims to identify features of the technological process of clinker formation. An analysis of deposits of gypsum raw materials in Kyrgyzstan was carried out. For the most common raw materials of limestones, their chemical and mineralogical composition was studied using the chemical, derivatographic and X-ray methods. By calculating raw mixtures, a charge was produced for obtaining sulfate-containing cement from limestone of the Tashkumyr deposit, local loams and clay-carbonate gypsum. The temperature regime of the clinker formation of sulfate-containing cements using local clay-carbonate gypsum awas studied. The article analyzes an effect of high temperatures on clay-carbonate gypsum whose chemical and mineralogical composition decreases the decarbonization temperature and causes the partial decomposition of CaSO4 and the early formation of primary clinker minerals. The use of gypsum rock with a high content of carbonates and clay impurities as a sulfate component in the preparation of sulfoclinkers helps to reduce the decomposition temperature of calcium carbonate and sulfate during burning. The data on the intensification of clinker formation are presented. They depend on the composition of charge components and the burning temperature, which correspond to the low-power technology. The technology can save energy, reduce CO2 emissions and improve the environmental safety.

Distinct chemical and mineralogical composition of Icelandic dust compared to northern African and Asian dust

Iceland is a highly active source of natural dust. Icelandic dust has the potential to directly affect the climate via dust–radiation interaction and indirectly via dust–cloud interaction, the snow/ice albedo effect and impacts on biogeochemical cycles. The impacts of Icelandic dust depend on its mineralogical and chemical composition. However, a lack of data has prevented an accurate assessment of the role of Icelandic dust in the Earth system. Here, we collected surface sediment samples from five major Icelandic dust hotspots. Dust aerosols were generated and suspended in atmospheric chambers, and PM10 and PM20 fractions were collected for further analysis. We found that the dust samples primarily consist of amorphous basaltic materials ranging from 8 wt % (from the Hagavatn hotspot) to 60 wt %–90 wt % (other hotspots). Samples had relatively high total Fe content (10 wt %–13 wt %). Sequential extraction of Fe to determine its chemical form shows that dithionite Fe (Fe oxides such as hematite and goethite) and ascorbate Fe (amorphous Fe) contribute respectively 1 %–6 % and 0.3 %–1.4 % to the total Fe in Icelandic dust. The magnetite fraction is 7 %–15 % of total Fe and 1 %–2 wt % of PM10, which is orders of magnitude higher than in mineral dust from northern Africa. Nevertheless, about 80 %–90% of the Fe is contained in pyroxene and amorphous glass. The initial Fe solubility (ammonium acetate extraction at pH 4.7) is from 0.08 % to 0.6 %, which is comparable to low-latitude dust such as that from northern Africa. The Fe solubility at low pH (i.e. pH 2) is significantly higher than typical low-latitude dust (up to 30 % at pH 2 after 72 h). Our results revealed the fundamental differences in composition and mineralogy of Icelandic dust from low-latitude dust. We attribute these differences to the low degree of chemical weathering, the basaltic composition of the parent sediments and glacial processes. Icelandic dust contributes to the atmospheric deposition of soluble Fe and can impact primary productivity in the North Atlantic Ocean. The distinct chemical and mineralogical composition, particularly the high magnetite content (1 wt %–2 wt %), indicates a potentially significant impact of Icelandic dust on the radiation balance in the subpolar and polar regions.

Silicate Brick with Reduced Density and Thermal Conductivity

Modern housing practice involves the widespread use of silicate brick. The main disadvantage of this building material is its high average density, accompanied by high thermal conductivity, which is accompanied by large heat losses through the enclosing walls of buildings and structures. This article discusses the possibility of improving the thermal characteristics of silicate materials through the use of ash microspheres in the production of piece silicate products, which will significantly reduce the thermal conductivity of the manufactured material. Ash microspheres, being a component of ash and slag waste from the thermal power plants, have a number of valuable properties: firstly, very low density, secondly, closed micro porosity, thirdly, chemical and mineralogical composition prone to reactions under conditions of elevated temperatures and pressures. We have studied the chemical and mineralogical composition as well as physical and mechanical properties of ash microspheres, developed the compositions and technological parameters for the silicate materials production. It has been established that the replacement of quartz sand with ash microspheres as part of the molding mass makes it possible to obtain a silicate brick of medium density class 1.0 and strength sufficient to erect load-bearing enclosing products and structures. Compositions of molding materials using a silicate binder and aluminosilicate ash microspheres using the generally accepted methods were developed and the properties of the obtained silicate material and were studied in accordance with the current GOST requirements for the similar materials.

THE POSSIBILITY OF USING CLAYS OF THE SAZDINSKY DEPOSIT IN THE PRODUCTION OF CERAMIC BRICK

Ceramic bricks is one of the most popular architectural finishing and structural materials. It has high efficiency and decorative properties. Expanding the raw material base of clay deposits in the production of ceramic bricks is an urgent task. In order to assess the possibility of using clays from the Sazdinsky Deposit (Aktobe region) in the production of ceramic bricks. Studies are conducted on four sections of clays from this deposit. The chemical and mineralogical composition of clays is studied, and the rational composition of raw materials is calculated. It is revealed that the studied clays have a polymineral composition, the main rock-forming minerals are kaolinite, illite and montmorillonite. According to the classification of A. I. Augustinik, the technological purposes of the studied clays are evaluated. The phase composition of samples heat-treated at different temperatures is studied. Based on the data of chemical and mineralogical composition of raw materials, technological properties of clays, physical-mechanical and operational indicators, it is established that the clays of three sites are suitable for the production of ceramic bricks by plastic molding. Phase composition of the obtained ceramic materials based on clays of four sites at a firing temperature of 1050 ° C are represented by quartz, hematite, anorthite, mullite, hematite and cristobalite. The strength of the fired samples of all clays corresponds to the brand 150-200. It is found that a more frost-resistant brick is obtained from the clays of the second section.

Influence of different types of chamot on a structure and properties of porous ceramics

The results of research of porous materials on the basis of products of ceramic production - chamot as a fractionating filler are given.. The features of formation of structure of material at the use of chamot with different chemical and mineralogical compositions in the conditions of speed baking are shown. Porous ceramics for filtration and aeration is obtained by a technology based on the regulation of porosity parameters by the use of chamotte of a certain granulometric composition and special binders. However, the granulometric composition of chamotte is a necessary but not sufficient factor to optimize the properties of porous filter ceramics. Along with the granulometry of chamotte, its chemical and mineralogical composition and surface energy must be taken into account. It depends in turn on the technological properties and the firing parameters of the original clay raw material. This paper presents the results of a study of porous materials based on ceramic products - chamotte as a fractionated filler. The chemical and mineralogical composition of chamotte made of poly-mineral clay at maximum firing temperature of 950°С and of refractory clay at firing at 1320°C was analyzed. The energy state of the surface of the chamotte particles was determined with the wetting by polar and non-polar liquids (water and benzene respectively). The differences in the specific effective surface area, lyophilicity and filtration coefficients was determined. The peculiarities of the formation of the pore structure of ceramics obtained using the specified samples of chamotte in the conditions of high-speed firing in the roller oven are shown. Significant differences in the formation of open and closed pores were observed, the predominant specific proportion of open pores in the material using polymineral clay. The possibility of properties regulation of the pore structure and the energy state of the surface of the filter material when applying a mixture of chamotte varieties was experimentally confirmed.