Study of iron content in iron ore concentrate increasing effect on sintering process indices and on metallurgical properties of sinter

Effectiveness of blast furnaces operation in many respects depends on metallurgical properties of agglomerate, in particular, iron content in the sinter and its basicity. At the same time, it is accepted that usage of iron ore concentrates with iron content more than 66–67% for sinter production results in decreasing of its strength. As a result of the planned modernization of the technological sections of the concentration plant JSC “Stoilensky GOK”, iron content in the concentrate will be increased to 68–70%. It makes it actual to accomplish comprehensive studies of metallurgical properties of the sinter while increasing iron content in the raw material. Results of the study of sinter properties presented, the sinter being obtained with utilization of iron concentrate with iron content 66.6 % (base), 68.0 and 69.2 % (exp. 1 and exp. 2 correspondently). The iron ore mixture for all the stages was the same and consisted of iron ore concentrate – 78.3%, sintering ore – 8.0%, lime – 5.5% and sintering additives (sludge, dust, scale) – 8.2%. The sintering mixtures composition for all the study stages differed only by fluxes and iron ore mixture consumption. 18 test sintering operations at three values of basicity 1.6, 1.8 and 2.0 units were accomplished. It was established that increase of iron content in the concentrate and basicity of the sinter results in improving of the sintering process indices, increase of the vertical sintering rate, sintering machines productivity, recovery and the sinter cold strength. Increase of the sinter basicity and its production with increased content of iron results in improving RDI indices at low temperature reducing. Results of the study of porosity indices and metallurgical properties of the sinter presented, in particular the collapsibility during reducing and temperature interval softening-melting presented. The advisability of concentrate with increased iron content utilization in the iron ore mixture shown.

Briquetting of porous alumina-containing materials with organic binders

Waste from corundum production in the form of porous alumina sludge is a promising material for providing ferrous metallurgy with cheap alumina-containing slag-formers. However, the direct feeding of the pulverized materials to the steelmaking furnace generally results in a significant carryover of such materials with waste gases. This paper considers the possibility of making briquettes from porous sludge of corundum production by cold briquetting using various common binders (molasses, cement, powder based on polyacrylamide, emulsion based on polyvinyl acetate). A comparison of the features of cold briquetting of powdered porous materials (slimes from the production of electrocorundum) and dispersed crystalline materials (fines of chrome ore) was made. Experiments were carried out to determine the impact strength of briquettes on different binder (“cold” strength) and tests to determine the “hot” strength (by the “thermal shock” test method). The authors have determined the consumption of the binder required to obtain satisfactory characteristics of briquettes from corundum slimes and from chrome ore fines. A technique has been developed and a mechanism for the binding of particles of loose and crystalline materials has been determined during briquetting using polyacrylamide powder. The destruction of a briquette of loose materials occurs mainly along the grains of the most porous material, and briquettes of crystalline materials are destroyed along the boundaries of the grains glued with a binder. For porous materials, the binder consumption increases more than twice as compared to briquetting on the same binder crystalline bodies of a fine fraction, and the binder must necessarily impregnate the entire volume of the porous material.

Analysis of the influence of coke quality on the production of pig iron in the conditions of JSC “Ural Steel”

The purpose of the study was to conformity of the quality of coke used in the blast-furnace shop of JSC “Ural Steel” meets the requirements recommended in the scientific literature, and to study its impact on the consumption of coke and the production of pig iron at the enterprise. For the study, the blast furnace № 1 with a useful volume of 1007 m3 and the blast furnace No. 4 with a useful volume of 2002 m3 were selected. The results of the analysis of data on the quality of coke over a three-year period: ash content, volatile matter and sulphur in the coke, the moisture content in the coke, the coke uniformity coefficient, indicators of the cold strength of coke (M25 and M10), indicators of coke hot strength (CSR) and reactivity of coke after high-temperature interaction with CO2 (CRI). Studies have revealed significant instability of the moisture content in the coke, which affects the change in its consumption, and heterogeneity of the granulometric composition of the coke, increasing the stability and uniformity of which would favorably affect the indicators of the blast furnace process. It was found that the values of the indicators of M10 coke attrition, hot strength of coke (CSR) and reactivity of coke (CRI) do not meet the recommendations of domestic and foreign scientists. Measures are proposed to improve the quality of coke, the implementation of which will increase the productivity of blast furnaces and reduce the consumption of coke per ton of pig iron.

Influence of the size of hematite and magnetite ores on the parameters of the sintering process and the quality of the sinter

Laboratory sintering of sinter charge based on hematite and magnetite iron ores of various sizes was carried out. The purpose of the study was to determine the effect of the type and size of the ore material on the gas permeability of the sintered layer, sintering performance and the need for fuel. The granulometric composition, cold strength, strength during recovery, and reducibility of the resulting agglomerate have been studied. Differences in the course of the process of agglomeration of hematite and magnetite ores at different sizes were revealed in the research. The established patterns have practical interest from the point of view of increasing the efficiency of the sintering process, improving the quality of the sinter and reducing the harmful impact on the environment.

Experiment Research on Power Molding and Destructive Distillation of Yaojie Oil Shale

Though the power molding of Yaojie oil shale, the optimum binder and proportion are confirmed. Hot strength,cold strength and oil yield of oil shale ball produced by power molding are measured. The results show that: Ⅰ , Ⅱ are suitable binders for power molding, besides, the hot strength and cold strength of oil shale ball produced by Ⅰ and Ⅱ are higher than 200N and 400N respectively. It can be found that from SEM, binders filling between particles of oil shale become gel or crystal after mixing with water. All that gel or crystal make particles connected closely and form net structure. The reason of low oil yield may be that the larger diameter of oil shale ball hinder the escaping of shale gas, and during escaping, shale gas is pyrolyzed because of long heating time, in addition, binders may absorb some shale gas.

Influence of Silicon Nitride on Properties of Corundum Based Castable

The effects of Si3N4 addition on the room temperature physical properties and thermal shock resistance properties of corundum based refractory castables were investigated using brown corundum, white corundum and alumina micropowder as the starting materials and pure calcium aluminate as a binder. The phase composition, microstructure, mechanical properties of corundum based castables were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that as the increase in Si3N4 addition, the bulk density decreased and apparent porosity increased, the cold strength deduced. However, the residual strength rate increased. That is, the thermal shock resistance was improved. This is because even though the introduction of Si3N4 inhibited the sintering of material and deduced the compactness, microcracks were produced in the materials due to a difference in thermal expansion coefficient. So the thermal shock resistance of corundum based castable was improved.

The Influence of B4C on Mechanical Properties of MgO-SiC Based Refractory Castables

The effects of B4C addition on the room temperature physical properties and hot mechanical properties of MgO-SiC based refractory castables were investigated using magnesia and SiC fines as starting materials and silica fume as a binder. The microstructure was characterized by scanning electron microscopy (SEM). The results showed that drying strength of MgO-SiC based castables decreased with the increase in B4C addition, the immediate temperature strength and hot temperature strength increased. The HMOR at 1400°C for 0.5h decreased. This is because B4C oxidized and produced a liquid phase during heating, contributing to sintering and making the material denser. So the cold strength increased. On the other hand, due to the formation of liquids, direct binding reduced and the HMOR decreased