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Prishtine, Croatia

Hoda Dr. S.,Fakulteti i Gjeoshkencave Dhe Teknologjise | Hoda Dr. S.,Lagja e Universitetit nr 2 | Zeqiri I.,Fakulteti i Gjeoshkencave Dhe Teknologjise | Sadiku M.,Fakulteti i Gjeoshkencave Dhe Teknologjise | And 2 more authors.
Kemija u industriji/Journal of Chemists and Chemical Engineers

Nowadays, there is a great need for materials that can withstand oxidative environment at very high temperatures. The most important material for such use is electrically fused MgO with melting point 3098 K and of great importance in the production of high-heat-resistant materials. MgO crystals obtained from melt have a regular structure, with few structural faults, compared to MgO crystals, which are formed at lower temperatures by sintering process. The goal of this work is the preparation of pure electrically fused MgO for use in electrothermics, from calcinated magnesite. Because the Republic of Kosovo possesses grade magnesite (MgCO, in this research for preparation of pure fused MgO in the electromelting furnace in Kosovska Kamenica samples of Strezovce magnesite deposit were used. After granulated fused MgO preparation, the optimum heat treatment and hardness were determined under controlled atmosphere, temperature range, and total time. Based on the research presented in this paper, it can be concluded that under optimal conditions at all stages, from calcined magnesite deposits of Strezovce, Republic of Kosovo, possible is the preparation of fused MgO for use in electrothermics, of quality comparable to MgO, which is available on the world market. Source

Hoda S.,Lagja e Universitetit nr 2 | Zeqiri I.,Lagja e Universitetit nr 2 | Sadiku M.,Lagja e Universitetit nr 2 | Kelmendi M.,Lagja e Universitetit nr 2
Kemija u industriji/Journal of Chemists and Chemical Engineers

The goal of producing and processing limestone ore (mostly CaCO 3) is to obtain high-quality refractory materials based on lime (CaO). Lime is the raw material for obtaining calcium metal as a strategic and fundamental component in lead metallurgy (production of refined lead, Pb-Ca alloys in the battery and cable industry, ferroalloys production with the addition of silicon and calcium, production of alloy steel and high-quality steel). This paper explores the preparation of lime by roasting the limestone deposits of Strezovci (Republic of Kosovo) and its use for obtaining calcium through the aluminothermic process. Through research and analysis of the chemical composition of certain types of lime, its suitability for obtaining calcium metal was determined, and by analyzing the samples of the slag, determined was the possibility of its use in the production of fire-resistant cement for which the evaluation is needed. Based on previous research, the following was chosen: optimal composition of the cast, volume of added reducing agents, and conditions of the reduction process performance: temperature- -time and initial vacuum. According to the authors' knowledge, not one Southeast European country has applied this method, and it includes the use of by-products (slag), which can cause environmental pollution. The goal of this research was to prepare lime by roasting limestone of domestic origin in order to obtain calcium metal through the aluminothermic process. The procedure of calcium metal production includes the following operations: decarbonatization of limestone ore (CaCO3), grinding of the obtained lime (CaO), homogenization of CaO and alumina, agglomeration, and aluminothermic reduction in vacuum furnaces. For the efficiency of the process, the most important technological operations are decarbonatization and reduction, provided the other operations are performed correctly. The estimated total world capacity for production of calcium metal is 25 000 - 27 000 tons/year. The mass fraction of calcium in manufactured calcium metal is minimum 97 %. In recent years, some western countries are producing calcium metal with 99.99 % of Ca, through redistillation and zonal refining. In the countries of Southeastern Europe and former Yugoslavia, the largest consumers were lead metallurgy, battery and cable industries, the steel industry and the producers of friction alloys. Based on the given results, the manufactured calcium metal can also be placed on other world markets. These studies have shown that the preparation of lime by roasting the limestone deposits of Strezovce (Republic of Kosovo) and its use for the aluminothermic obtaining of calcium metal is possible. This would stop imports and initiate exports, as well as create conditions for serious research into the application of calcium metal for industrial purposes, and thus keep pace with global technological development trends. Source

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