Engineering in Action

Improvements in operational performance of the refractory lining of a direct-current electric furnace for cobalt smelting achieved at the Ufaleinikel Joint-Stock Co. in collaboration with the Kombinat Magnezit Joint-Stock Co. are reported.     

New Carbon-Containing Refractories for the Lining of Steel-Teeming Ladles from the Kombinat Magnezit Joint-Stock Co.

Test results for new carbon-containing refractories for the lining of steel-teeming ladles — PUSK, PShUK, PShUP, PUPK, and ShPUP-grade, available from the Kombinat Magnezit JSC, are presented. The properties of refractory components (including heat resistance) in the as-received and subjected to coking condition are reported. The enhanced resistance of the new materials to thermal spalling under varying temperature conditions is noted. Results of the tests (carried out at the Magnitigorsk Iron-and-Steel Works and Oskol'skii Electrical ISW) provide the basis for an analysis of the economic feasibility of large-scale production of these materials.     

Stress-strain state of slotted grips

The stress-strain state of the slotted grips of broad-range centering clamp mechanisms is theoretically and experimentally investigated.     

The choice of an optimal composition and preparation method of non-promoted Pd/Al2O3 and promoted Pd-Co/Al2O3 catalysts for the selective hydrogenation of vinylacetylene

For the purpose of optimizing the chemical composition and technology of synthesis of the catalyst for the acetylene hydrocarbons hydrogenation in industrial streams of butadiene and ethyl-vinylacetylene fractions, the influence of the palladium initial compound nature, the active component concentration, the promotion by cobalt, the molar ratio of palladium to cobalt, the phase composition of the supporter on physical chemical properties, and the activity and selectivity to 1,3-butadiene of the catalysts was studied. The effect of acidic-base characteristics of the supporter on its ability to oligomerize unsaturated hydracarbons has been investigated. It has been established, than the δ-Al₂O₃ supporter is characterized by a low concentration of Bronsted and Lewis acidic sites, decreasing the quantity of oligomers formed on its surface. The optimal composition of the non-promoted KGV-07 catalyst, recommended for the raw butadiene fraction hydrogenation, is 0.5% of Pd deposited from palladium acetate on δ-Al₂O₃ with palladium particles of 16 nm in size, on which the vinylacetylene conversion of 100% and the selectivity to 1,3-butadiene of 69.9% are reached at a temperature of 20°C at the reactor input, hourly space velocity (HSV) of hydrocarbon raws of 700 h⁻¹, molar ratio of hydrogen to ethyl-vinylacetylenes of 4: 1, summary concentration of 49% of acetylene hydrocarbons, and 1.5% of 1,3-butadiene in hydrocarbon raws. The synthesis of the cobalt-promoted KGVP-07 catalyst with 0.5% of Pd deposited from palladium acetylacetonate on δ-Al₂O₃ and molar ratio of Pd: Co = 1: 1 has been developed for the hydrogenation of an ethyl-vinylacetylene fraction with a concentration of acetylene hydrocarbons to 6 wt %, with the vinylacetylene conversion of 100% and the selectivity to 1,3-butadiene of 61.3%, at HSV of the hydrocarbon stream of 700 h⁻¹, temperature of 6°C at the reactor input, and molar ratio of hydrogen to ethyl-vinylacetylene admixtures of 4: 1. Promotion by cobalt leads to the formation of palladium particles at the zero oxidation level and to an increase in their average size from 11 to 14 nm in comparison with the non-promoted Pd-catalyst. In the work, IR-spectroscopy, transmission electron microscopy (TEM), and physicochemical methods have been used to characterize the catalysts texture and supporter phase composition. Pilot tests of the KGV-07 and KGVP-07 catalysts on the Etilen plant unit have proven the correctness of the choice for the catalysts’ optimal chemical composition.     

A Study of the Kinetics of Decarbonization of Magnesite Concentrated by Flotation

The kinetics of decarbonization of magnesite concentrated by the method of flotation is studied in a laboratory under various conditions (stationary unblown layer, fluidized layer, layer mixed in a rotary furnace). Typical features of the process of decarbonization of magnesite are determined (constancy of the temperature of the material up to a decarbonization of 80 – 90%, self-fluidizing of the roasted material due to intense emission of CO₂ gas, etc.).     

Periclase-Carbon Refractories from the Kombinat Magnezit JSC for Use in Converter Steelmaking Technology at the Magnitogorskii Metal-and-Steel Works JSC

Cooperation between the Kombinat Magnezit Joint-Stock Co. and Magnitogorskii Metal-and-Steel Works Joint-Stock Co. in the area of exploitation of converter refractories is briefly outlined. Prospects for further improvement of the performance characteristics of refractories and converter design are discussed.     

Synthesis of Spinel from Caustic Magnesite and Alumina Dust

The sintering of a mixture of a caustic dust and an alumina dust collected from electric filters taken in MgO/Al₂O₃ ratios of 0.1, 0.28, 0.5, and 0.75 at 1650°C is studied. Materials with superior physicomechanical properties are obtained: open porosity, 1.2 – 8.4%; density, more than 3.5 g/cm³, and compressive strength, 160 – 410 MPa. High-density pellets (free of additions) are prepared at a MgO/Al₂O₃ ratio of 0.75, with compressive strength as high as 160 MPa.     

Effect of promotion with cobalt or zinc on the hydrogenating and oligomerizing activities of the Pd/Al2O3 catalyst in the hydrogenation of the BTX fraction

The promoter nature and content effects on the catalytic activity and stability of Pd-Co/δ-Al₂O₃ and Pd-Zn/δ-Al₂O₃ bimetallic catalysts in the hydrogenation of dienic and vinyl aromatic hydrocarbons in the BTX fraction have been investigated by IR spectroscopy and temperature-programmed reduction. The Pd : Co (Zn) molar ratio in the catalysts prepared is 1.0 : 0.5, 1.0 : 1.0, or 1.0 : 1.5, and their Pd content is 0.5 wt %. The support is δ-Al₂O₃ doped with sodium (0.5 wt %). Promotion of the palladium catalyst with zinc and cobalt causes the disappearance of cationic palladium species, thereby reducing the oligomerizing capacity of the active component, and, as was demonstrated by 100-h-long catalytic tests, enhances the stability of the catalyst. The Pd-Co/δ-Al₂O₃(Na) catalyst with Pd : Co = 1.0 : 1.0 mol/mol is recommended for the hydrogenation of the BTX fraction under industrial conditions. The expected service life of this catalyst between regenerations is 16 months.     

Low-pressure gas-discharge current interrupters in a generator of high-voltage nanosecond pulses with an inductive energy storage

Designs of grid units with slotted and multiple-aperture configurations of holes that allow an increase in the stability of the current-cutoff process and a reduction in the time to turn the device off in a high-voltage pulse generator with an inductive energy storage were created. Compared to a TGI2-500/20 thyratron, these designs made it possible to reduce the time instability of the instant of the current interruption by factors of 2 and 5 for switches with the multiple-aperture and slotted configurations of the grids, respectively. These constructions allowed the minimum time for disabling a device to be reduced by 25%.     

Pilot tests of a catalyst for the selective hydrogenation of acetylene

Pilot tests of SGA-2M promoted Pd/Al₂O₃ catalyst in the selective hydrogenation of acetylene are performed on an industrial ethane-ethylene fraction in a system of two serially arranged adiabatic flow reactors. The optimum process conditions under which the conversion of acetylene reaches 100% at a selectivity of 68.2% with respect to ethylene are determined: system pressure, 21 atm; hydrocarbon feedstock hourly space velocity (HSV), 1500 h^?1, carbon monoxide concentration, 7 ppm; H₂: C₂H₂ molar ratio at the first and second hydrogenation stages, 1.0: 1.0 and 1.4: 1.0; inlet temperature of the first and second reactors, 40 and 55°C, respectively. The interregeneration service life of the SGA-2M catalyst under optimum conditions is estimated at 12 months. SGA-2M catalysts can be recommended for purifying ethane-ethylene fractions containing up to 2 vol % of acetylene.