A study on the characteristics of coke in the hearth of a superlarge blast furnace

An in-depth study on the characteristics of coke in the hearths of blast furnaces is of great significance for explaining the mechanism of coke deterioration in blast furnaces. In the present work, the changes in macromorphology, degree of graphitization, and microstructure of the coke taken from different hearth locations of a 5,800 m3 superlarge blast furnace during its intermediate repair period were systematically studied. Significant differences were found between cokes obtained from the edge (“edge coke”) and from the center (“center coke”) of the hearth in terms of properties and degradation mechanisms. Edge coke was severely eroded by liquid metal, and only a small amount of slag was detected in the coke porosity, whereas center coke was basically free from erosion by liquid metal, and a large amount of slag was detected in the coke porosity. The degree of graphitization of edge coke was higher than that of center coke. The carburizing effect of liquid metal was the main cause of the degradation of edge coke and made it smaller or even disappear. Center coke was degraded due to the combination of two factors: slag inserted into micropores on the surface of center coke loosened the surface structure; and graphite-like flakes that appeared on the center coke surface lowered the strength and caused cracks in the surface.

Development of technology for lining steel-tapping hole of steel-teeming ladles with the use of nesting well blocks

At OJSC «BSW – Management Company of Holding «BMC» were tested nesting well blocks for lining of steel-tapping hole of steel-teeming ladles ЭСПЦ-1, 2 with the working lining of piece goods. In the conditions of the enterprise during the full campaign of the working lining of steel ladles, intermediate repair of the slag belt, bottom blowing units and the steel-tapping holes is carried out. The steel-tapping hole is used to release steel from the steel ladle into the intermediate ladle. The purpose of the tests is to replace the «traditional» filling of the steel outlet with refractory concrete manually by molded nesting wellblocks due to the reduced risk of accident due to the lack of probability of metal «penetration» into the concrete, as well as reducing the volume and duration of repair of the working lining of steel ladles.

Development perspectives of metal gas-dynamic stirring in a ladle with a side lance application

Blow-off of a liquid metal bath through a lance, located in the bottom part of a ladle wall, is usually considered as one of well-known long time ago variant of steel refining in ladle. However, despite a wide repute and availability of a series of advantages, the technology was not widely spread. An estimation of stirring efficiency and splashes formation at different variants of compressed air supply made. The studies were done at a transparent water model with a color indicator application. It was determined, that upper and bottom lances shifting relating to ladle symmetry axle promotes the stirring intensification and simultaneous decrease of splashes height. The best results were obtained at the simultaneous utilization of asymmetrically located submerged lance and a side lance, oriented in gas-liquid flow direction in the bottom part of the vessel. The side lance is more preferable in maintenance, since for them a ladle fringe is not required as in the case with bottom lances, it is not subjected to falling metal stream action as well as to metal and slag residuals action after tapping finishing. It is possible to provide an improvement of stirring conditions and metal tapping by shifting and inclination of a side lance. Industrial tests showed, that a facility for metal blow off through porous insertions, installed in ladle wall, have a high throughput ability, provide a reliable operation within a course of ladle lining campaign without intermediate repair. It does not require capital outlays and can be recommended for industrial application.

Mechanistic modelling and Bayesian inference elucidates the variable dynamics of double-strand break repair

DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution. Here we present a new method to model the combined activation of non-homologous end joining, single strand annealing and alternative end joining, following exposure to ionizing radiation. We use Bayesian statistics to integrate eight biological data sets of double-strand break repair curves under varying genetic knockouts and confirm that our model is predictive by re-simulating and comparing to additional data. Analysis of the model suggests that there are at least three disjoint modes of repair, which we assign as fast, slow and intermediate. Our results show that when multiple data sets are combined, the rate for intermediate repair is variable amongst genetic knockouts. Further analysis suggests that the ratio between slow and intermediate repair depends on the presence or absence of DNA-PKcs and Ku70, which implies that non-homologous end joining and alternative end joining are not independent. Finally, we consider the proportion of double-strand breaks within each mechanism as a time series and predict activity as a function of repair rate. We outline how our insights can be directly tested using imaging and sequencing techniques and conclude that there is evidence of variable dynamics in alternative repair pathways. Our approach is an important step towards providing a unifying theoretical framework for the dynamics of DNA repair processes.