Browsing by Author "Marinov M."
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Item Balance modeling of the process for SiCaV alloy producing from waste vanadium catalyst(2014-02-25) Petrov P.; Marinov M.; Todorov P.; Alexandrova R.; Paunova R.The modern steel industry is characterized by continual improving the quality of the produced steel with constantly increasing range and quantity of deoxidation and alloying alloys. Among them falls SiCa with vanadium. Consider the absence in the Republic of Bulgaria of raw materials containing vanadium for example, the needs of metallurgy are provided mainly by imports of ferro-alloys. At the same time our country has an active chemical and metallurgical industries where significant polluting quantities of vanadium catalyst drop from production of sulfuric acid, which contains Si and V. Both material and heat balance models are developed for carbothermal producing of SiCa with a high content of vanadium. Vanadium waste, metallurgical lime and metallurgical coke are the raw material. The elements in the alloy after the carbothermal reduction are: V - 9.09 %, Fe - 9.06 %, Si - 66.45 %, Ca - 12.26 %, P - 0.02 %, S - 0.04 %, C - 0.21 %, Al - 2.83 % u Mn - 0.03 %. The main contributor into the alloy of V, Si and Fe is the waste vanadium catalyst. The relative consumption of electricity according to the heat balance model is 11505 kWh/ton alloy.Item Electric-arc-carbothermic processing of agglomerated waste dispersal materials from ferrous metallurgy(2014-01-01) Grigorova D.; Marinov M.; Paunova R.The present paper reports results referring to the production of pig iron under laboratory conditions using a low shaft electric furnace. Wastes from ferrous metallurgy subjected to a preliminary agglomeration are used as iron containing raw materials in the sintering charge. Material and heat balance calculations are carried out. It is found that sinters of high waste powders and sludge content can be used to give pig iron of low content of sulphur, phosphorus and non ferrous metals. The chemical composition, the yield and the specific energy consumption are found close to the existing standards.Item IMIDAZOLIDINEDIONE DERIVATIVES OF NALIDIXIC ACID: SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL STUDIES(2021-01-01) Marinov M.; Kostova I.; Naydenova E.; Stoyanov N.Imidazolidine-2,4-diones (hydantoins and spirohydantoins) and nalidixic acid (1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid) are heterocyclic compounds whose ring structures include nitrogen atoms. These substances exhibit potent pharmacological activity as antitumor, antibacterial and antifungal agents, as well as aldose reductase inhibitors. This article presents the synthesis of novel heterocyclic compounds, based on the interaction of imidazolidinediones with nalidixic acid. The imidazolidinedione derivatives obtained were characterized by physicochemical parameters, elemental analysis, IR, 1H and 13C NMR spectral data. The biological activity of the synthesized products was evaluated against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae and the mold Aspergillus brasiliensis. All compounds showed activity against the Gram-positive and Gram-negative bacteria tested.Item New platinum(II) complexes of cycloalkanespiro-5-(2-thiohydantoins). Synthesis and quantum chemical investigation(2015-01-01) Marinova P.; Marinov M.; Delchev V.; Stoyanov N.Synthesis and characterization of new Pt(II) complexes of cyclohexanespiro-5-(2-thiohydantoin) (L1) and cyclohepta-nespiro-5-(2-thiohydantoin) (L2) are discussed. The new complexes are studied by elemental analysis, IR and 1H NMR spectroscopy. The free ligands are investigated by UV-Vis, IR, 1H NMR, 13C NMR and Raman spectroscopy. The ground-state equilibrium geometries of the ligands L1 and L2 and their complexes with Pt(II) are optimized at the BLYP/CEP-31G theoretical level.Item OPportunities for obtaining of deoxidizing and alloying alloy by metallurgical utilization of vanadium waste(2017-01-01) Petrov P.; Marinov M.For the contemporary steel production, deoxidizing and desulfurizing alloys produced via ferroalloys metallurgy are required. Such kind of alloys is silicocalcium. When its production is accompanied by additives containing alloying elements, the alloy obtained has alloying properties at its import in a certain steel grade. Using of a few hundredths of the alloying elements (such as vanadium, niobium, etc.) to the steel quantity increases significantly its strength indexes. The most common minefields of vanadium contain about 1% vanadium in the form of complex compounds with various elements. This makes uneffective their direct utilization in the ferrous metallurgy. There are corporate organizations that are manufacturing products from vanadium-containing raw materials. One of these products is vanadium catalyst - material that is distributed in factories for production of sulfuric acid. After a certain period of use it is deactivated and deposited and it contains significantly higher amounts of natural vanadium. It contains over 60 % SiO2. Catalyst utilization in a combination with calcium-containing materials via pyrometallurgical method is an optimal opportunity for both environmental protection and preparation of precious metallurgical alloys as silicocalcium. Currently in Bulgaria imported and expensive silicocalcium is being used. The paper presents the results of laboratory calculations using three methods for silicocalcium production with increased vanadium content.Item Production efficiency of a ferro-molibdenum alloy(2014-02-25) Marinov M.; Mushev G.; Petrov P.; Paunova R.; Aleksandrova R.Ferro-molybdenum alloys are widely used in the production of heat-resistant stainless steel, acid-proof, tool steels. They give an uniform grain size, increase the tenderness, etc. Imported in the iron, molybdenum increases the hardness, the elasticity and the durability. FeMo is not produced in Bulgaria. The need of this ferro-alloy is covered by imports, which significantly increases the cost of the production. In this aspect, it is of an great interest the evaluation of the profitability of the organization at such proceedings in the country, based on the imported concentrate of MoO3, defining the necessary quantities of raw materials, technological operations, material flows and machines for a set annual production of FeMo60. The relative fuel charge materials is calculated based on the composed material and heat balance models of metal heat outside furnace production of ferro-molybdenum with an use of both aluminum and ferrosilicon as a gear. The technical and economic feasibility of profitable production is examined. The necessary raw materials for an annual production, both the daily and the hourly average and the one for the combustion furnace hearth are determined. A block diagram of a small factory, a sample processing of raw materials and necessary equipment are proposed.Item Study on the behaviour of flotation fayalite waste from copper production at nonisothermal heating(2014-02-25) Alexandrova R.; Paunova R.; Marinov M.; Petrov P.The behaviour of flotation fayalite waste from copper slag at non-isothermal heating has been studied. Only a small part from this product (about 2 %) is used in the cement production. The other part, containing rather high percentage of iron is not used and it is deposited thus polluting the environment. DTA method was used to study the behavior of this waste at the non-isothermal heating up to 1273K and 1673K. Phase transformations have been defined by chemical and X-ray analyses. The phases of hematite, magnetite and cristalobalite were determined in the end product after flotation. Thermograms, obtained by DTA show that the oxidation processes run into two stages at the non-isothermal heating - the first stage up to T = 894K and the second one up to T = 1155K. Experimentally, the melting temperature of the flotation fayalite waste (Tmelt ≈ 1457K) was found. The melting of the sample in the crucible was observed at this temperature.Item Study on the synthesis, characterization and bioactivities of 3-methyl-9'-fluorenespiro-5-hydantoin(2016-01-01) Marinova P.; Marinov M.; Kazakova M.; Feodorova Y.; Slavchev A.; Blazheva D.; Georgiev D.; Penchev P.; Sarafian V.; Stoyanov N.This work describes a method for synthesis, as well as in vitro antiproliferative and antibacterial investigation of 3-methyl-9'-fluorenespiro-5-hydantoin. The structure of the substituted fluorenylspirohydantoin derivative was verified by UV-Vis, FT-IR, Raman, 1H NMR and 13C NMR spectroscopy, and by using a combination of 2D NMR experiments, which included 1H-1H COSY, HMQC and HMBC sequences. The geometry of the compound was optimized by the B3LYP density functional with 6-31G(d) basis set and the 1H and 13C NMR spectra were predicted with the HF/6-31G(d) calculations at the optimized geometry. The anticancer activity of the 3-methyl-9'-fluorenespiro-5-hydantoin was determined in suspension cell lines originating from tumors in humans (WERI-Rb-1). The cytotoxic effect was evaluated by WST-assay (Roche Applied Science). The antimicrobial effect of the compound against Gram-negative, Gram-positive bacteria and the yeast Candida albicans was investigated.Item Synthesis and antimicrobial activity of 1,8-naphthalimide derivatives of nalidixic acid(2019-01-01) Marinov M.; Kostova I.; Naydenova E.; Stoyanov N.Various naphthalimides are synthesized and their biological activity is studied. The target compounds are prepared by the interaction of different substituted 2-amino-1H-benzo[de]isoquinoline-1,3(2H)-diones with nalidixic acid (1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid). The structures of all synthesized products are verified via their physicochemical parameters, an elemental analysis, IR, 1H and 13C NMR spectroscopy. The antimicrobial activity of the compounds obtained is determined against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Essherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae and the molds Penicillium chrysogenum and Aspergillus niger. It is found that N-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide, N-(6-1H-indol-3-yl-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide and N-(6-piperidin-1-yl-1,3-dioxo-1H-benzo[de] isoquinolin-2(3H)-yl)-1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxamide are active against the Gram-positive and Gram-negative bacteria tested.Item Synthesis and antimicrobial study of new Pt(IV) and Ru(III) complexes of fluorenylspirohydantoins(2019-01-01) Marinova P.; Marinov M.; Georgiev D.; Becheva M.; Penchev P.; Stoyanov N.The present work presents a synthesis, characterization and antimicrobial activitiy of new Pt(IV) and Ru(III) complexes of (9’-fluorene)-spiro-5-hydantoin (HL1) and (9’-fluorene)-spiro-5-(2-thiohydantoin) (HL2). The complexes were investigated by elemental analysis, UV-Vis and IR spectroscopy. The free ligands were studied by UV-Vis, IR, 1H NMR, 13C NMR and Raman spectroscopy. The antimicrobial tests of HL1 showed week bacteriostatic effect against Staphylococcus aureus ATCC 6538. The results for [Pt(L1)2(H2O)2(OH-)2] complex showed a good antimicrobial activity against Esсherichia coli ATCC 8739, Bacillus licheniformis ATCC 6633, S. aureus and the absence of such effect on the yeasts. The HL2 and its [Pt(L2)2(H2O)2(OH-)2] and [Ru(L2)3(H2O)3] complexes do not possess antimicrobial activity against the tested bacteria and yeasts.Item SYNTHESIS AND CHARACTERIZATION OF N3-ACETYL DERIVATIVES OF SPIROHYDANTOINS(2022-01-01) Marinov M.; Frenkeva M.; Naydenova E.; Penchev P.; Stoyanov N.The following article describes the synthesis of N3-acetyl derivatives of spirohydantoins. The compounds are derived by applying the following technique: the Bucherer-Lieb method (α-series) and the Strecker method (β-series). The synthesized products are characterized by physicochemical parameters, elemental analysis, FTIR, 1H NMR, 13C NMR and 13C DEPT135 spectral data.Item Synthesis and in vitro activity of platinum(II) complexes of two fluorenylspirohydantoins against a human tumour cell line(2014-01-01) Marinova P.; Marinov M.; Kazakova M.; Feodorova Y.; Penchev P.; Sarafian V.; Stoyanov N.This paper presents a method for synthesis and cytotoxicity of new platinum(II) complexes of (9′-fluorene)-spiro-5-hydantoin (L1) and (9′-fluorene)-spiro-5-(2-thiohydantoin) (L2). The new obtained complexes were studied by elemental analysis: ultraviolet-visible, attenuated total reflection Fourier transform infrared (ATR-FTIR), and 1H- and 13C-NMR for Pt(II) compounds and additionally Raman spectroscopy for free ligands. Based on the experimental data, the most probable structure of the complexes is suggested. In the present study, we have examined cytotoxic activity of (9′-fluorene)-spiro-5-hydantoin (L1) and (9′-fluorene)-spiro-5-(2-thiohydantoin) (L2) and their Pt(II) complexes on the retinoblastoma cell line WERI-Rb-1. © 2014 The Author(s). Published by Taylor & Francis.Item Utilization of waste powder and sludge in iron ore sintering process(2014-01-01) Grigorova D.; Tsanev T.; Marinov M.Extraction metallurgy is characterized by low rate waste emissions utilization. The greater part of the dust and sludge generated by the gas cleaning facilities does not return to production. Their accumulation leads to ecological problems. The present study treats theoretically calculated and experimentally obtained series of sinters of various basicity and concentrations of sludge and waste mixture. The latter contain sinter powder, blast furnace powder, convertor dust and electric arc furnace powder of a ratio corresponding to that yearly observed under real production conditions. The main characteristics of the sintering process are established. The results reveal that the main characteristics of sintering process do not significantly change in case of using waste powders and sludge.