Characterization of polymetallic ore and flotation concentrate from the Mária Mine (Rožňava, Špis-Gemer Ore Mts., Eastern Slovakia)

The contribution deal with the study on composition of tetrahedrite-bearing siderite ore from Maria Mine nearby Rožnava and of tetrahedrite concentrate prepared from this ore by froth flotation. The Rožnava ors field consists of two main vein systems, namely Mária and Strieborná (Argenteous/Silvery) ones, respectively. The both vein systems are situated in the Early Paleozoic Gelnica Group of the Gemeric Superunit, in Bystrý Potok Formation (Upper Silurian) and in the Drnava Formation (Early Devonian). The filling of vein systems is formed mainly by siderite, quartz, tetrahedrite, pyrite, arsenopyrite, chalcopyrite, ankerite, albite, pyrrhotite, marcasite, less tourmaline, sericite, chlorite, apatite, magnetite, etc. The rock surroundings is represented by quartzy metapsammite, sericitic-quartzite and sericitic-graphitic phyllites (Jakubiak, 2008, Blišt’an, 2009, Varga, 2013, Mikus, 2018). Thus, metal ore as a feed to froth flotation and obtained concentrate were subjected to grain size analysis. The grain size fractions were assayed using GA, AAS, MS-ICP and CHNS. Mineral composition of samples was studied using XRD. So, polymetal ore contains 18.99 % SiO2, 37.01 % FeO, 1.84 % MnO, 7.36 % C, 2.36 % Cu, 1.70 % Sb, 0.15 % As, 2.32 % S, 770 ppm Ag and 216 ppm Hg. Tetrahedrite concentrate containing 25.59 % Cu, 19.68 % Sb, 1.19 % As, 20.08 % S, 0.57 % Ag, 1.20 % Hg, 1 % SiO2, 16.16 % FeO, 0.48 % MnO and 2.17 % C at a mass yield of 4 % was prepared. XRD study showed that siderite occurs as a dominant mineral in metal ore. Quartz, tetrahedrite and sericite are presented as accompanying minerals. Accessories are represented by chlorite, probably clinochlore. As to flotation concentrate, tetrahedrite is dominant mineral, which accompanied by siderite. Accessories can be represented by chalcopyrite, arsenopyrite, sericite, pyrite, quartz and chlorite.

Thermodynamic Analysis of Siderite Ore Carbonate Decomposition Process at Roasting

Carbonate decomposition with significant heat energy absorption takes place at siderite ore oxidizing roasting in a shaft furnace. Thermal dissociation of complex carbonates comprising the siderite ore was studied. Thermodynamic analysis was carried out for a sideroplesite decomposition process. Formulas allowing determination of the carbonate dissociation and exchange energy rates were obtained using the regular ion solution theory. The ion composition and thermodynamic activity simulation results were described for sideroplesites as well as iron and magnesium cation shares. The work output is of certain interest as knowing the initial sideroplesite decomposition temperature and the carbonate dissociation rate the optimal dimensions of various zones throughout the shaft furnace height may be defined, the roasting process time may be calculated and the optimal heat treatment conditions as well as the firing rate may be established.

Improvement of the technology for processing siderite ore from the Bakal deposit

The Urals is one of the unique iron ore provinces of the world, including all the variety of iron ores. Siderite ores are represented by the Bakal group of deposits, in which siderite in mineralogical terms is not a chemically pure iron carbonate, but has an isomorphic admixture of magnesium and calcium, forming sideroplesite and pistomesite. The main iron ore mineral of the siderite ore of this deposit is an isomorphic mixture of iron, magnesium and manganese carbonates, which occur in different quantitative ratios. A scheme for ore dressing is proposed, which includes crushing to a size of 10-0 mm and dry magnetic separation in a suspended state at a magnetic field strength of 52 k/m. The study of dry magnetic separation of siderite ore was carried out on a suspended separator with a constant magnetic field and on an electromagnetic separator 138T-SEM. The resulting magnetic fraction is sent to the baking, subsequent crushing to a size of 2-0 mm and dry magnetic separation in the suspended state. To increase the mass fraction of iron and reduce the mass fraction of magnesium oxide, the magnetic fraction is sent for grinding and wet magnetic separation. The results of the experiments have showed that the enrichment using high-intensity dry magnetic separation of siderite ore from various sections of the deposit, the mass fraction of MgO decreased from 9.4-12.3% to 8.0-10.1%, and the mass fraction of iron increased from 28.8-33.4% to 31.4-40.8%. As a result, a product with a mass fraction of iron 59.3-60.1% and magnesium oxide 10.0-11.3% has been obtained. The developed enrichment technology allows us to obtain conditioned raw materials, which can serve as a promising raw material for PJSC Magnitogorsk Iron and Steel Works (PJSC MMK)

Research on Siderite Ore Reducing Firing

It was determined that the current method of the Bakalsk mining department siderite ore preparation for blast-furnace smelting does not allow production of concentrate meeting the state-of-the-art metallurgy requirements. The most perspective method is reducing firing when a metallized product with higher iron content is obtained. It was demonstrated that implementation of this method requires the use of a three-zone shaft furnace having the oxidizing roasting zone, the reduction zone and the reduced product cooling zone. Experiments were carried out on the siderite ore reducing firing on laboratory units. The possibility in principle was demonstrated for production of the reduced product with iron content of 60 – 65% from the siderite ore. After the magnetic dressing the concentrate with iron content of 65 – 75% was obtained. It was determined that firing and reduction in hydrogen atmosphere result in the fired product reduction degree of 97 %. The possibility to produce a product suitable for blast-furnace conversion with the reduction degree of about 60% with the use of natural gas air conversion gas was demonstrated. The obtained results were used in the process development for the siderite ore reducing firing in a three-zone shaft furnace.

Optimization of Siderite Ore Sintering Operation Conditions

Research was сarried out on a pilot plant on sintering of various size siderite ore and limonite taken in various ratios. To study impact of a number of process factors on the sintering process performance and the obtained agglomerate quality at the minimum number of the carried out experiments, one of the experiment planning methods was used, and regression equations were derived. With these equations the effect of the ore size, siderite ore and limonite ratio, solid fuel consumption, sintered layer height on the agglomeration unit performance and the agglomerate metallurgical properties was reviewed. The obtained work results have great practical importance, as they allow optimization of siderite ore sintering operation conditions and production of high quality agglomerate. They may be used at a variety of the country agglomeration factories, where siderite ores will be used as iron ore component of the sinter burden.

Process Development for Solid Fuel Use at Siderite Ore Roasting in Shaft Furnace

Lean coal burning kinetics was studied and the main burning rate dependence on oxygen content in gas phase and heating rate was obtained. Preliminary dressed lump siderite ore from Bakal deposit with the fraction of 18-25 mm and average iron content of 35% was roasted in a pilot unit in neutral (low reducing) atmosphere, obtained by coal grate firing. It was established that such roasting allowed iron oxidation level reduction, as compared to roasting in oxidizing atmosphere and iron content increase in the roasted product. The evaluation results allowed development of a roasting process for siderite ore in neutral (low reducing) atmosphere and designing of a shaft furnace operating on solid fuel. Such roasting process is of a certain interest, as far as saving the insufficient fuel types, and predominantly natural gas, is concerned.

Determination of physical heat capacity of metallurgical production materials by additivity method

Heat capacity is one of most important thermal physic characteristics of materials, allowing determining dependence between amount of heat, input to a body or taken away from it, and alteration of its temperature. The labor intensiveness of the test determination of the heat capacity is rather big. Particularly it is difficult to take into account the influence of changes of chemical composition in the process of heating on changes of their heat capacity. A method of calculation of heat capacity of materials proposed using the additivity method. Difficulties of its determination shown, related to insufficient knowledge of additivity method application. The temperature limits determined, until which it is reasonable to make the calculations of materials heat capacity by the proposed method. An example of calculation of siderite ore physical heat capacity considered. Good enough convergence of the results obtained by calculation and heat capacity data, obtained by experiments shown. Divergence between results of heat capacity determination by experiment method and by calculation using additivity method does not exceed 5%. The considered method of physical heat capacity determination can be used also for other materials providing the content of separate components and their changes within the temperature range under the study is known.