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A new method is proposed for agglomerating iron-ore-bearing materials. The method involves moistening the charge with up to 7.5-9% pulp containing dust-sized waste products from the processing of brown iron ores. The ores are ferruginous chlorites (chiefly amesite, chamosite, and penninite). The have a coarseness of 0.074 mm. The ore content of the pulp is within the range 1.5 to 75 wt. %. The chlorites have the following chemical composition (wt. %): Fe 2 O 3 , 41.2, SiO 2 24.0, Al 2 O 3 13.07, FeO 11.23, Cr 2 O 3 3.96, MgO 2.35, CoO 0.86, NiO 0.58, CaO 0.53, MnO 0.06. Sintering of Mikhailovskii ores and concentrates with the use of the pulp under laboratory conditions made it possible to increase the unit productivity of the sintering machine 2.9%, increase the impact strength of the sinter 4.5%, and increase its abrasion resistance 17.1%. Keywords: sinter, impact strength of sinter, abrasion resistance of sinter, unit productivity of sintering machines, vertical sintering rate.The purpose of sintering iron-ore-bearing materials is to prepare them for smelting in blast furnaces. The use of quality sinter can significantly increase the efficiency of the smelting operation and make it more cost-effective.Being a raw material used in blast-furnace smelting, iron-ore-bearing sinter needs to have the following quality characteristics: maximal iron content; stable chemical composition; good mechanical strength at low and high temperatures; low abradability; minimal content of fines (0-5 mm); high initial softening point; narrow softening-point range; good reducibility; a basicity value which ensures the removal of raw limestone from the blast furnace.One quantitative characteristic of the sintering operation is the unit productivity of the sintering machine. In order to perform the sintering operation correctly, it is necessary to optimize the process parameters for the specific composition of the material being sintered. Sinter quality and the unit productivity of the sintering machine are most heavily influenced by the following process parameters: the composition of the material being sintered; the coarseness of that material; the amount of undersize; the material composition, quantity, and coarseness of the various additions that are used; the character of the charging operation and the associated segregation of the charge materials; the quantity, coarseness, and qualitative composition of the fuel added to the charge; the effectiveness of the charge-mixing operation; the moisture content of the charge; the presence of a bed of fines; the bulk density and height of the layer of charge materials; the vacuum created by the exhauster; the initial temperature of the charge.Among the shortcomings of existing methods of sintering are unsatisfactory mixing of the charge materials and the limit on the quantities of dust-sized materials that can be introduced into the charge. This situation results in uneven moistening of the charge as a whole, creates cavities, and reduces gas permeability and vertical sintering rate.Our...

At the present time, technological progress in the construction and maintenance (repairs) of thermal units requires mass-scale application of heat-resistant concretes whose specifications are becoming more stringent due to the developments taking place in the technology and the techniques and the intensification of the processes occurring in the thermal units. In view of the fact that high-alumina cement (HAC) is the most promising binding (bonding) agent for the refractory concretes working at a temperature exceeding 1773~ (under controlled atmospheres also), numerous studies have been carried out [1][2][3][4] for identifying the possible methods of improving its properties and for understanding the mechanisms and the kinetics of the reactions occurring during its synthesis.We carried out extensive (complex) studies aimed at identifying the optimum technological parameters for producing clinker of HAC by sintering in order to improve the service properties of the concretes based on the cement obtained from this clinker. This paper presents the results of the studies conducted on the kinetics of the solid Dhase reactions occurring during the sintering process of the clinker.In order to study the stability of the individual phases and compounds and to establish the most general regularities in the occurrence of the solid-phase reactions, thermodynamic analysis is carried out using the principle of calculating the change in the isobaric potential (AG) with respect to the compositions (constitutuents); the application of this principle involves investigation of each possible reaction under the assumption that the quantity of the initial substances is identical [5].The change AG was calculated by integrating the Gibbs-Helmholtz equation.The following equations depicting the temperature dependence of AG were obtained on the basis of the cal~ culation carried out taking into account the polymorphic transformation of 7-A1203 into ~o AI203 :A G O = --6584,470 --7,102 TIn T q-2,400 X 10-3T~--2,710 9 105T-'~-39,994T (for the aluminate having the composition ClzAT) ;A G~ = --7529,960 --6,830 T In T q-1,690,10-aT2--2,675 9 105T-'q-38,288T(for the aluminate having the composition CA) ; and 218T (for the aluminate having the composition CAz)Based on the obtained equations, the values of AG~ were calculated at different temperatures in the I073-1873"K range for the compounds CA, CAz, and C12A 7. The results of our calculations (Fig. I) showed the thermodynamic feasibility (possibility) for the formation of the aluminates CA and C12A 7 in the mixture of the experimental (system) (besides calcium dialuminate having a more negative value of AG o in the entire temperature range under consideration). The conclusion regarding the thermodynamic probability of formation of the aluminates CA, CA2, and CI2A 7 in the experimental system agree with the data of Fedorov et al. [4].It is known that the occurrence of a reaction depends not only on the magnitude of AG, but also on the kinetic factors among which the rate and the activation en...

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