Papers by Keyword: Minerals

Abstract: Functional foods containing minerals, nutrients, as well as other active ingredients are essential to support physiological functions. The Chlorophyta macroalga Ulva lactuca (“sea lettuce”) is a popular natural food source due to its abundance in intertidal zones across Indonesia. To further examine its efficacy to the human physiology, analysis of proximate composition (carbohydrate, protein, fat, crude fibre, ash, and moisture content), macronutrient (Na, P, Ca, K, and Mg), micronutrient (Fe, Mn, Cu, Zn, Co, and Cr), heavy metal (Pb, Hg, and Cd), and fatty acid contents need to be done. Results showed that the highest composition of macromolecules is carbohydrates. Macronutrients and micronutrients with the highest values are Mg and Fe, respectively, with Ca also showing a high concentration. Pb and Hg contents are considered safe, but the Cd content exceeds the safety limit regulated by BPOM 2008. The fatty acids contained include methyl octadecenoate and the unsaturated fatty acid linolelaidic methyl ester. Mg, Ca, and Fe have important roles in the body’s systems, i.e., metabolic processes, growth and development, and enzyme activation. The presence of these elements suggests U. lactuca’s potential in maintaining the body’s physiological functions; however, the relatively high content of Cd must be noted.

Abstract: Calcium titanate (CaTiO₃) was synthesized through combustion in air from calcium sources of raw minerals (lime-stone and calcite), anatase titanium dioxide (A-TiO₂) and magnesium (Mg). The syntheses were divided into two reactant systems (lime-stone/A-TiO₂/Mg and calcite/A-TiO₂/Mg. Before synthesis, the raw minerals and A-TiO₂ were high-energy milled for 30 min. These powders were then separately mixed with Mg by ball milling. After synthesis, the as-combusted products were leached with 2 M HCl solution to remove by-products and impurities. A sequential mechanism for the in-situ combustion was proposed by using data from simultaneous thermal analysis (STA) together with thermodynamic values calculated with HSC^ software. XRD results showed that the as-leached products from both reactant systems mainly contained CaTiO₃. FT-IR spectroscopy indicated that the as-leached products had Ca-Ti-O and Ti-O functional groups. In addition, SEM observation of the as-leached products revealed cuboid-like crystals with a particle size of about 100 nm.

Abstract: The paper presents the results of the research for the reasons of the formation of a brownish bloom on a light clinker brick during its operation. In the work course, the clinker bricks, their mineralogical composition, the nature of the secondary brick coloring and the base materials were tested during bricklaying. It was established that 2 factors caused incrustation. Firstly, the site on which the clinker brick was laid was characterized by a level of alkali soil water close to the surface, and the surface evaporation prevailed over the soil absorption in the warm period of the year. That is all soil water-dissolved salts migrated to the surface of the brick along well-permeable sand joints between the bricks. Secondly, ferrous minerals, including hematite, which was subjected to hydration with the formation of iron hydroxides, and also reacted with sulphates of groundwater with the formation of iron sulphates, were found in the foundation under the brick. This confirms the higher sulfur content in incrustation areas and the presence of a film similar to crystalline hydrates. The analysis of the research allowed us to develop the recommendations for the performance of paving various types of sites with clinker bricks, to develop measures to eliminate an existing bloom, and also to defend the “honor and dignity” of light bricks.

Abstract: The paper presents the results of the studies on the phase conversions taking place during the firing of the refuse piles processing sieve residue in the Eastern Donbass, which are the promising raw materials for the production of various types of structural ceramics – common, lining and clinker bricks, high-performance ceramic stones, ceramic tiles and siding. It is established that the sieve residue is the raw material of the low-temperature baking. Depending on the degree of grinding, the raw material may belong to the group of mid-baking or high-baking raw materials. The sieve residues have a rather narrow baking interval - no more than 50 °C, which is possible to expand by increasing the content of fine fractions during the preparation of sieve residue. The main mineral phases at the firing temperature of 1000-1100 ^оС are quartz, feldspar, ferrous silicates and aluminum silicates (fayalite, hypersten, etc.), hematite. The features of the phase and mineralogical conversions allow us to recommend to fire products on the basis of sieve residue at temperatures of 1000 °C and higher.

Abstract: This article offers a qualitatively new approach for production fused welding fluxes granules, based on the use of a plasma arc and the Ural region raw materials that have a particularly low content of harmful impurities. The processes of fused welding flux granules forming from the Ural region mineral raw materials under the impact of a highly concentrated energy source have been studied. A new fused welding flux for submerged arc welding is produced by plasma electric arc granulation, and has required shape and fractional, chemical and phase composition of the particles. This research presents experimental and theoretical studies of interaction processes of fine-dispersed batch from mineral raw materials with a highly concentrated energy source, aimed at obtaining new information about the basic patterns of the formation, structure and composition of resulting granules of functional materials, such as welding fused fluxes.

Abstract: The article outlines the main principles of granulation technology for fused welding flux using highly concentrated heat sources (e.g. plasma arc). Modern plasma equipment and methods of its use for producing new welding materials (plasma-granulated welding flux) from mineral raw materials and synthetic mineral alloys are described. The developed technology makes it possible to produce granulated flux in a wide range of fractional composition (from 0.2 to 3 mm). Studies have focused on the influence of granulation regimes (plasmatron moving speed, current, voltage, arc length) on formation process and the morphology of welding flux particles. Mineral raw materials used for granulation were igneous rocks (basalt, hornblendite) and synthetic mineral alloys. The results obtained during experiments on the use of highly concentrated heat sources for granulation of a fused welding flux confirm the feasibility and prospects of this technology. Typical equipment for air-plasma cutting is used, and no new complex technological equipment is required, therefore it eliminates large material and labor costs.

Abstract: The purpose of the work is the obtaining of magnesium silicate ceramic proppants, based on ultrabasic overburden rocks of Kempirsai deposits of chromite ores (Kazakhstan). The chemical and mineralogical composition of ultrabasic overburden rock was studied by chemical, microscopic and X-ray diffraction analyzes. It is established that the main mineral of ultrabasic overburden rocks is serpentine, present in the form of fibrous chrysotile and lamellar antigorite. In the impurities are iron oxides and hydroxides, chrome spinel, carbonates, quartz. Assessment of the use of overburden rocks as a raw material for the production of ceramic proppants was carried out. The sintering interval of overburden rocks was determined at 1280-1300 °C. The sintering firing optimum temperature of ceramics, based on this type of raw material is 1300 °C. It is established that to harden the structure of magnesium silicate ceramic it is necessary to activate the raw material thermally at a temperature of 1000 °C. The influence of binder type on the properties of magnesium silicate proppants, based on the Kempirsai serpentinites was studied. Magnesium silicate proppants, based on ultrabasic overburden rocks, were obtained with the following properties: apparent density – 1.6 g/cm³, strength resistance (52 MPa) – 14%, sphericity and roundness – 0.8; chemical resistance (hydrochloric acid) – 98%, static strength of the fraction 16/20 - 72–118 N/granule. The field of application is oil and gas production, metallurgy and ceramic industries.

Abstract: The general characteristic of products of processing of waste heaps is given. Their characteristics by fractional composition are proposed: large-fractional, with grains from 2 to 150 mm in size, medium-fractional with a grain size of 0.5 to 2 mm, and fine-grained with a grain size of 0 to 0.5 mm. The results of work on the study of the chemical-mineralogical composition and physico-mechanical properties of the medium-fractionation products of the waste heaps processing with reference to the production of various wall ceramics products are presented. Their role is shown as a polyfunctional additive when introduced into ceramic masses and affects the properties of finished products. A preliminary classification according to the amount of coal component, mineralogical and petrographic composition, technological properties is proposed. The feasibility of their application in the production of wall ceramics with a reduced cost is given.

Abstract: A viewpoint that suggests that grain/ interphase boundary sliding (GBS) that develops to a mesoscopic scale (“cooperative boundary sliding”) controls optimal superplastic (SP) deformation is able to explain superplasticity in metals and alloys, ceramics, intermetallics, composites and bulk metallic glasses of grain sizes ranging from a few microns down to a few nanometers. It is extended here to describe grain-size-sensitive (GSS) flow in minerals, rocks and ice within narrow experimental ranges. In this approach the accommodation processes of grain boundary diffusion, dislocation emission from sliding boundaries and/ or grain rotation accompanying boundary sliding are present over extremely short distances and are assumed to be faster than GBS. Analysis shows that GSS creep in geological and glacial materials can be accounted for in terms of four “universal”, mesoscopic scale constants of average values, = 0.197, = 0.415 J.m^-2, = 8.9 and = 0.166, where is the average shear strain associated with a basic boundary sliding event at the level of the atomistics, is the specific grain boundary energy (assumed to be isotropic), is the number of boundaries that align to form a mesoscopic boundary glide plane and “” is a constant that obeys the condition 0<a<0.5, whose magnitude depends on grain shape and size distribution in the material. It is demonstrated that with the help of these four constants and the Frost-Ashby equations for estimating the shear modulus, it is possible to predict steady state GSS creep flow in any geological or glacial material, including those whose mechanical response was not used to obtain the “universal” constants. Whether these observations are evidence for “superplasticity” in these materials can be known only if the findings are reproduced in tensile deformation also.

Abstract: The research and description of modern methods and procedure of welding flux manufacture are presented. The technology of welding fused flux production by influencing on the composition of mineral raw materials furnace burden (from 0,5 mic up to 0,20 mm) with electric arc (diameter graphite electrodes 6-18 mm, current from 200 up to 600 A) is proposed to be significantly reducing the labor input as well as dustiness during the operation and transport and improves mechanical properties (granules strength of 16-19 N/mm²) and surface condition of flux granules. The equipment for the granulation does not require large melting furnace and powerful transformers, fuel gas, coke or oil, i.e. welding flux is easy to manufacture.