Authors suggest removing hydrogen sulfide from the hot industrial gas at temperatures 200-300 °C and its subsequent interaction with Fe 2 O 3 . For this purpose the following sorbents have been proposed: a mixture of iron oxide and fly ash; iron oxide and pumice; different samples of red mud (bauxite treatment residues containing iron oxide). To prevent dusting and loss of absorbing capacity, the sorbents were shaped into porous granules with other metallic oxides. Materials utilized in the study were obtained the following way: mixing of Fe 2 O 3 with fly ash; sintering of the mixture with red mud. The blend contains aluminum oxide and silica, which can act as matrix shapers, alkali oxides and fluxing agents that reduce the temperature during metal sintering. After the samples had been saturated with sulfur, they were positioned in a venting reservoir, where under the temperature 600-700 °C desorption to the initial state occurred by means of passing an air flow through the sorbent layer. In the process of this operation, sulfur dioxide was released and reactive metal oxides re-emerged. Desorption also generated a small amount of elemental sulfur and sulfuric acid. Absorbing capacity was assessed at higher temperatures, efficiency of H 2 S removal reached 95-99.9 %. Proposed technology of air cleaning is recommended to use in metallurgic processes with elevated atmospheric pollution, e.g. granulation of melted blast-furnace slag.
In the aluminum industry, the largest amount of waste is red mud (RM). that is a solid bauxite residue after hydrochemical processing and extraction of alumina. The topicality of its processing was shown by the ecological catastrophe in Hungary (2010), where the bund wall of the slurry storage was destroyed and the viscous mass of fine red mud fell on thousands of hectares of land. The risks of a recurrence of such a catastrophe increase due to the increased natural disasters: earthquakes, torrential rains and floods, as well as terrorist attacks. Therefore, it is proposed to exclude the storage of red mud in sludge storages and organize its shipment in transportable form to processing complexes. The article presents the results of scientific research and the experience of complex processing of red sludge on an industrial scale with the production of new types of marketable products.
A problem of industrial fluxed agglomerates self-destruction in the process of cooling after sintering has been examined. It has been revealed that the main reason of strength degradation is polymorphism of dicalcium silicate Ca2SiO4 (or short designation С2S): β-Ca2SiO4 ® γ-Ca2SiO4. Ways for increasing the agglomerate strength by physical and crystal-chemical stabilization of the high temperature modification of C2S have been proposed and tested. Physical stabilization of C2S agglomerate is increased with its structure reinforcement due to thickening of walls between large pores that is achieved by increasing height of the sintered layer through improvement of its gas permeability. The task is addressed by substituting the previously used import sintering ore with the polydisperse ore from the Yakovlevo field, which improves the charge pelletizing by 3-4 times and helps to bring the height of the sintered layer and the strength of the domestic agglomerate up to the international best practice standards, while eliminating a need to purchase import high-vacuum exhausters. In practice crystal-chemical stabilization of C2S within iron-ore agglomerate is ensured by adding an opti- mal multicomponent additive in the form of the waste product generated in production of alumina from bauxites, i.e. the red mud, to the initial sinter charge. Thus mechanical strength of agglomerates and pellets is increased by 5-10 % and their hot strength improves by 20-40 %. The productivity of sintering machines and blast furnaces improves by 5-10 %. Specific coke consumption reduces by 2-2.5 %. In production of iron-ore pellets red mud is substituting the import bentonite.
The work reveals the ability of the Yakovlevskiy mine sinter ore to improve pelletizing of a sinter mix, to reduce its flow resistance in 4-5 times, to increase capacity of a sinter machine, to improve the sintering uniformity and sinter quality, to reduce consumption of agglomeration solid fuels and coke. Application of the Yakovlevskiy sinter ore moves sintering process to a modern technical level of charge in the sintering bed 500-600 mm in height without the use of expensive high-vacuum exhausters.
Are considered the advantages and disadvantages of complex processing red mud to produce alumina, iron (cast iron) and cement on the area of alumina refineries and way of getting on them only transportable red mud – for shipping and recycling of new marketable products at operating enterprises.
Agglomerates, sintered of the bauxite and limestone are need to reduce coke consumption in blast furnace slag smelting of high-alumina in order to get out of it quick-and heat-resistant cement. The peculiarity of such a high basicity sinter (the ratio of CaO / SiO2). The paper presents the results of studies demonstrating the ability of the liquid phase in the formation of sinter almost completely assimilate the lime. Bauxite highly basic sinter can be durable and resistant against destruction with open storage.
Extreme dependence of the strength of sinter from its basicity is explained by content in the agglomerate iron and calcium silicates, which form a bundle of strength sinter. Minimum strength of sinter corresponds basicity about 1,2-1,4. This proves the attempts to optimize the technology of this agglomerate with the planning of the experiment. Laboratory experiments have shown that the basicity of sinter with 1,4 at the optimal linear velocity of its sintering about 18,7 mm/min, obtained an acceptable yield ratio not more than 65 %, even at elevated (above 6 %) fuel rate. In order to increase the maximum strength of the agglomerate in this extreme dependence appropriate to increase the content of iron oxide. Found that with the increase in iron content of 1,5 % yield of the agglomerate increases by 1 %. It is noted that the increase in iron content in the agglomerate after the maximum strength can lead to some of its decline, due to increased melting of the charge and decreases the amount of a strength ferritic-calcium binding.
A brief analysis of the main variant using of sinter ore Yakovlevskaya are given in respect that it is specific chemical composition. Production sponge iron technology and Midrex HYL are not require the consumption of scarce coke. Metallurgical coke can be save large amounts on modern steel plants through the using of iron-rich materials with a low content of harmful impurities (sulfur and phosphorus). Given the feasibility study and comparison of the above options.
