Browsing by Author "Petrov P."

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    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.
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    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.
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    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.
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    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.