scholarly journals Exploitation of Kaolin as an Alternative Source in Alumina Production

2021 ◽  
Vol 5 (1) ◽  
pp. 24
Author(s):  
Bagani Maria ◽  
Balomenos Efthymios ◽  
Panias Dimitrios

The extensive consumption of aluminum, combined with the shortage of the existing raw materials, and particularly bauxite, necessitates the exploitation of alternative raw materials for the production of alumina. The present paper focuses on the possible use of kaolin, as an abundant, cheap and high-aluminum content raw material, in alumina production, via the application of the Aranda-Mastin technology in the leaching step. From this point of view, leaching experiments were conducted on untreated kaolin and thermally treated, metakaolin, applying atmospheric pressure, temperature of 90 °C and with an aqueous solution of a low HCl concentration as the leaching agent. Leaching, in the aforementioned conditions, is an industrially applied process, characterized by highly efficient aluminum dissolution in the case of metakaolin with low silicon dissolution at a short retention time, but with respectively lower achieved results for untreated kaolin. In order to raise the aluminum dissolution rate from untreated material, temporal and subsequently chemical intensification was applied. The analysis indicated a higher aluminum dissolution rate, up to 70%, with the application of a high acid concentration of leaching agent, performed for a long retention time that could be further improved.

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 734
Author(s):  
Maria Bagani ◽  
Efthymios Balomenos ◽  
Dimitrios Panias

The increasing demand for aluminum in conjunction with the limited available bauxite deposits in Europe results in the dire need for the evaluation of alternative raw materials for the whole value chain of alumina production. The present paper focuses on the possible use of nepheline syenite, originated as a mine byproduct, in alumina production through leaching with an azeotropic HCl solution. Previous work on nepheline syenite dissolution focused more on the extraction of potassium and sodium values. In this work, emphasis is given at the characteristics and leachability of aluminum content phases by applying a high temperature HCl leaching in untreated material. From this point of view, leaching experiments were conducted on nepheline syenite, at a temperature range of 90 °C to 150 °C and with aqueous azeotropic HCl solution. Leaching, in the aforementioned conditions, is a process, characterized by medium aluminum dissolution. The results show that the aluminum-bearing phases that withstand the dissolution process are mainly the ones of sodium and potassium feldspars.


2008 ◽  
Vol 59 (2) ◽  
pp. 129-134
Author(s):  
Ion Teoreanu ◽  
Roxana Lucia Dumitrache ◽  
Stefania Stoleriu

Any change of the raw material sources for glazes, economically, ecologically motivated, and also from the glaze quality point of view, is conditioned by the molecular formula rationalization and by the variation limits of the molecular formula, respectively. The proper glaze compositions are placed within their limit variation intervals with optimized processing and utilization properties. For this purpose, the rationalization criteria and procedures of molecular formulas are summarized in the present paper, as well as the results referring to their rationalization obtained in the authors� previous work. Thus, one starts from a base of raw materials that are selected, usable and also accessible for the design and producing of the glazes. On these bases the groundwork and the design equation for the glaze recipes are developed, exemplified for a single glaze. For an easy access to results, computer programs are used for an easy access to results.


2021 ◽  
pp. 47-50
Author(s):  
Антонина Григорьевна Чернобровина ◽  
Наталья Николаевна Роева ◽  
Наталия Евгеньевна Куликова ◽  
Ольга Юрьевна Попова

В настоящее время к одним из наиболее приоритетных направлений пищевой промышленности относят разработку функциональных продуктов питания на основе экологически чистого сырья естественного происхождения, в том числе ягодного. При разработке новых продуктов с защитными свойствами важно учитывать ингредиентный состав сырья, оказывающий лечебно-профилактический эффект, и с этой точки зрения ягоды малины и брусники заслуживают особого внимания. С целью максимального извлечения и сохранения природных, физиологически-функциональных компонентов дикорастущих ягод (витаминов, микро- и макроэлементов, фенольных, пектиновых соединений и др.) были разработаны и созданы мультиэнзимные композиции для предобработки ягод брусники (МЭКб) и малины (МЭКм). Большой интерес вызывали исследования состава и содержания красящих веществ в исследуемых образцах. В качестве структурных элементов антоцианов в соке малины и брусники, а также в их ферментативных соках установлены дисахариды, основной структурный компонент которых - цианидин. Количественное содержание антоцианов в соке брусники и малины составило 305,4 и 106,2 мг/дм3, а в ферментативном соке брусники (БФС) и малины (МФС) - 553,7 и 146,4 мг/дм3, соответственно. Высокое содержание красящих веществ - важный критерий для использования БФС и МФС в качестве источника натуральных красителей. Установлена более высокая антиоксидантная активность в БФС и МФС (соответственно в 1,3 и 1,5 раза) по сравнению с соком, полученным без применения ферментных препаратов. Следовательно, ферментативный сок ягод обладает высокими антиоксидантными свойствами и служит источником натуральных красителей, поэтому его можно рассматривать как перспективный сырьевой полуфабрикат при производстве продуктов питания функциональной направленности, оказывающих благотворное регулирующее действие на организм человека. Currently, one of the priority areas of the food industry is the development of functional food products based on environmentally friendly raw materials of natural origin, including berry. When developing new products with protective properties, it is important to take into account the ingredient composition of the raw materials, which has a therapeutic and prophylactic effect, and from this point of view, raspberries and lingonberries deserve special attention. In order to maximize the preservation and extraction of natural, physiologically functional components of wild berries (vitamins, micro - and macroelements, phenolic compounds, pectin and other substances) were developed and created multienzymatic compositions for the pretreatment of lingonberry (MEKb) and raspberry (MEKm). Of great interest were studies on the characterization and content of dyes in the samples being studied. As structural elements of anthocyanins in raspberry and lingonberry juice, as well as in their enzymatic juices, disaccharides were established, the main structural component of which is cyanidine, and the quantitative content of anthocyanins (mg/dm3) in the juice of lingonberry and raspberry, corresponded - 305.40 and 106.20, and in the enzymatic juice of lingonberry and raspberry - 553.70 and 146.40. The high content of dyes is an important criterion for the use of BFS and MFS as a source of natural dyes. A higher antioxidant activity was found in BFS and MFS (1.3 and 1.5 times, respectively) compared with juice obtained without the use of enzyme preparations. Therefore, the enzymatic juice of berries has high antioxidant properties and is a source of natural dyes, so it can be considered as a promising raw material in the production of functional foods that have a beneficial regulatory effect on the human body.


2012 ◽  
Vol 42 (4) ◽  
pp. 283-294
Author(s):  
Ľudovít Kucharič ◽  
Vladimír Bezák ◽  
Dušan Majcin ◽  
Ján Vozár

Abstract A positive gravity anomaly was observed in the Flysch belt realm. Based on this fact and available geological knowledge we suppose that the source of gravity anomaly might be carbonate rocks lying perhaps in the footwall of Flysch sediments. The carbonates belong perhaps to the Penninic crust cover (a part of Klippen belt), or to lower structural stage of the Flysch belt. Besides this it is interpreted more volume of Neogene subvolcanic bodies in the frame of the Flysch belt based on the results of the newest magnetic measurements in the NE part of Slovakia (Kucharič et. al., in press). These are accompanied by increasing heat flow and hydrothermal alteration within neighbouring rocks what may eventuate into creation of raw materials. These two factors - carbonates and subvolcanic bodies - are important items for appraisal of new perspective in this area not only from hydrocarbon occurrences point of view (a primary intend within this area) but also for enhancement of geothermal potential of Slovak Republic and opening possibilities for prognosis of raw material occurrences as well.


2019 ◽  
Vol 73 (4) ◽  
pp. 265-274
Author(s):  
Slavica Mihajlovic ◽  
Zivko Sekulic ◽  
Jovica Stojanovic ◽  
Vladan Kasic ◽  
Iroslav Sokic ◽  
...  

Quality of raw materials, including quartz sand and quartzite, varies from one deposit to another. Furthermore, the material quality determines in which industrial branches it can be used after certain preparation processes. Potential applications of quartz raw materials are: in the construction and refractory industry, ceramics and glass industry, then in metallurgy, foundry and also in production of water treatment filters. Geological investigations of the central Serbia region, in the Rekovac municipality, resulted in identification of occurrence of quartz sand ("Ursula") and quartzite ("Velika Krusevica"). Preliminary laboratory tests and characterization of the quartz sand size fraction -0.63+0.1 mm confirmed the possibility of applying this size fraction in the construction materials industry, while the quartzite can be used in refractory, glass and metallurgy industries. After determining the geological reserve of quartz sand "Ursula" and quartzite "Velika Krusevica", detailed investigations are required. Quality conditions from the aspect of chemical composition and physical properties of quartz sand and quartzite are mostly clearly defined by a special standard for this purpose. On the other hand, there are also application areas where standards does not exist, but users define their quality conditions. This example is with the application of quartz sand in the production of water glass. Chemical composition as well is not always the determining factor for the application of quartz raw material. For example, for quartz sand used for sandblasting, grain form is essential. From the economic analysis point of view, the prices of quartz raw materials vary depending on their chemical and physical properties. After all, what needs to be pointed out is the fact that these raw materials are very widespread in nature and that their exploitation is quite simple. After the raw material is excavated, it is stored and further sieved, washed, dried and processed according to customer requirements. All of these processes are cheaper than preparing, for example, limestone, and significaly cheaper than preparation of metal ores.


2020 ◽  
Author(s):  
Sara Daffara ◽  
Gabriele L.F. Berruti ◽  
Marta Arzarello

The Ciota Ciara cave is a Middle Palaeolithic site located in Piedmont (north-western Italy) and it is the only one systematically investigated in the region. It opens at 670 m a.s.l. on the west side of Monte Fenera and its archaeological deposit has a stratigraphic sequence documenting several and repeated human frequentations. Four archaeological layers have been identified (13, 14, 15 and 103) and are characterized by lithic assemblages where vein quartz is the main exploited raw material. The upper level (13), was already subject to technological and functional studies but the enlargement of the excavated area made necessary a completion of the technological data. The aim of this work is to deal with a complete technological and functional study of the lithic assemblage of the four archaeological layers of the Ciota Ciara cave to face the issues of predetermination and adaptation of the reduction sequences to the raw materials features. The technological analysis is based on the concept of chaîne opératoire and refers to the classical definitions of the S.S.D.A., discoid and Levallois methods for the identification of the different exploitation strategies. The concepts of curated and expedient technology are also applied to the present study. We finally refer to the huge debate concerning the concept of predetermination related to cores that show reduced or none phases of core configuration for the analysis and interpretation of the considered lithic assemblage.The results obtained show that the general behaviour can be interpreted as expedient, both from a technological and a functional point of view. The Middle Palaeolithic hunter-gatherers of the Ciota Ciara cave adapted their “technological background” to the resources available and put into action flexible adaptation strategies. Even in the shortness or absence of phases of core configuration, predetermination can be observed in the adaptation of Levallois and discoid concepts to the natural constraints of the pebbles chosen as cores. The natural convexities are exploited to obtain Levallois and discoid flakes after an intentional choice made by the knappers. In order to deeply investigate the characteristics of the technological behaviour of the hunter-gatherers that inhabited the site, the use-wear analysis is a fundamental additional source of information and it is here aimed to understand if there is or not a differential use of the lithic artefacts according to their typology and/or to the knapping method.


2020 ◽  
Vol 1 (383) ◽  
pp. 192-198
Author(s):  
Z. K. Ayupova ◽  
D. U. Kussainov ◽  
M. T. Beisenbayeva ◽  
Winston Nagan

In the XXI century the role of Central Asia in international politics is increasing. This region, possessing rich natural, energy, mineral and raw material resources, has an important geostrategic position, in which we see the geopolitical confrontation of global actors. The confrontation is explained by the fact that, for example, for Russia this region, being a “vulnerable underbelly”, is included in the traditional sphere of influence, from the perspective of China, the region seems to be an alternative source of energy and a vital partner for stabilizing and developing the troubled Xinjiang province. As for the United States and their allies, this region appears to be an important transportation hub, for example, for military supplies to unstable Afghanistan. Central Asia is not only a key region on the world map, the establishment of control over which allows you to manage the regional transit of hydrocarbons and other types of strategic raw materials for the largest developing economies, primarily China, and, as a result, affect their economic growth and aggregate power. Central Asia is a crossroad of civilizations, control over which, as was believed over the centuries, allows you to rule the world. The region retains its exceptional geopolitical significance today.


2021 ◽  
Vol 5 (1) ◽  
pp. 85
Author(s):  
Aikaterini Toli ◽  
Georgia Maria Tsaousi ◽  
Efthymios Balomenos ◽  
Dimitrios Panias ◽  
Matthias Heuer ◽  
...  

Calcium aluminate slag produced by the aluminothermic reduction of silica is tested as a candidate raw material for the hydrometallurgical production of pure aluminium chloride hexahydrate (ACH) through leaching with hydrochloric acid. The crystallization of ACH follows by sparging the pregnant liquor with hydrochloric gas. Almost total extraction of Al is achieved with the use of azeotropic HCl acid solution (5.9 M) at 80 °C and 1 h retention time. A pregnant liquor with approximately 20 wt% AlCl3 is produced as a base for ACH crystallization by sparging it with gaseous HCl. The ACH produced is re-dissolved and crystallized three to four times until high purity is achieved. High purity ACH acts as a precursor for producing High Purity Alumina (HPA), a high added value material used in LEDs and lithium-ion batteries and other niche applications.


2021 ◽  
Vol 4 (1) ◽  
pp. 9-17
Author(s):  
Miklós Tisza

Abstract In recent decades, the automotive industry has faced ever-increasing demands. Increasing requirements can be observed in terms of both consumer expectations and legal requirements. On the consumer side, there is a demand for cars that are as economical as possible with lower fuel consumption, but providing also greater comfort and safety. These requirements are accompanied, from a legal point of view by more rigorous environmental regulations and requirements concerning the reduction of harmful emissions. Meeting these often-contradictory requirements is a growing challenge for car manufacturers and raw material suppliers, as well. Meeting the requirements in the most versatile way has resulted in tremendous progress over the last 40–50 years, both in the automotive industry and in the production and development of raw materials. The first part of this series of papers summarizes the main requirements in the automotive industry, as the main driving forces for material developments. Furthermore, the main types and properties of traditional high-strength steels, as well as the so-called first-generation Advanced High-Strength Steels will be introduced. In the second part, the main types and manufacturing processes of second generation advanced high-strength steels will be analyzed and some of the current steel developments will be presented through the results of the three generations of Advanced High-Strength Steels.


2020 ◽  
Vol 10 (18) ◽  
pp. 6222 ◽  
Author(s):  
Girts Bumanis ◽  
Jelizaveta Zorica ◽  
Diana Bajare

The potential of phosphogypsum (PG) as secondary raw material in construction industry is high if compared to other raw materials from the point of view of availability, total energy consumption, and CO2 emissions created during material processing. This work investigates a green hydraulic ternary system binder based on waste phosphogypsum (PG) for the development of sustainable high-performance construction materials. Moreover, a simple, reproducible, and low-cost manufacture is followed by reaching PG utilization up to 50 wt.% of the binder. Commercial gypsum plaster was used for comparison. High-performance binder was obtained and on a basis of it foamed lightweight material was developed. Low water-binder ratio mixture compositions were prepared. Binder paste, mortar, and foamed binder were used for sample preparation. Chemical, mineralogical composition and performance of the binder were evaluated. Results indicate that the used waste may be successfully employed to produce high-performance binder pastes and even mortars with a compression strength up to 90 MPa. With the use of foaming agent, lightweight (370–700 kg/m3) foam concrete was produced with a thermal conductivity from 0.086 to 0.153 W/mK. Water tightness (softening coefficient) of such foamed material was 0.5–0.64. Proposed approach represents a viable solution to reduce the environmental footprint associated with waste disposal.


Sign in / Sign up

Export Citation Format

Share Document