Blast Parameters Research Articles

Hot metal yield optimization of a blast furnace based on constructal theory

Constructal theory is introduced into the hot metal yield maximization of the blast furnace in this paper. Generalized constructal optimization of a blast furnace is performed for a specified total raw material cost. The optimal distribution of each raw material cost in the total cost, namely “generalized optimal construct”, is obtained. Besides, the optimal charge composition of the blast furnace is also obtained. The effects of blast parameters, agglomerate ratio and pulverized coal dosage on the optimization results are analyzed. The results show that the hot metal yield after generalized constructal optimization is 1027.4 kg, and is improved by 2.64% compared with that before optimization. For actual production of the blast furnace, when the total cost is fixed, decreasing the blast oxygen enrichment, blast volume, and agglomerate and increasing pulverized coal dosage can increase the hot metal yield. Increasing blast humidity can increase the hot metal yield when the blast humidity is always under a certain value. The contribution of this paper is to optimize the hot metal yield of the blast furnace based on new methodology, which leads to a good economic performance of the blast furnace iron-making process and provides new guidelines for the design of this process.

Development of a new model for predicting flyrock distance in quarry blasting: a genetic programming technique

This research was aimed at developing a new model to predict flyrock distance based on a genetic programming (GP) technique. For this purpose, six granite quarry mines in the Johor area of Malaysia were investigated, for which various controllable blasting parameters were recorded. A total of 262 datasets consisting of six variables (i.e., powder factor, stemming length, burden-to-spacing ratio, blast-hole diameter, maximum charge per delay, and blast-hole depth) were collected applied to developing the flyrock predictive model. To identify the optimum model, several GP models were developed to predict flyrock. In the same way, using non-linear multiple regression (NLMR) analysis, various models were established to predict flyrock. Finally, to compare the performance of the developed models, regression coefficient (R2), root mean square error (RMSE), variance account for (VAF), and simple ranking methods were computed. According to the results obtained from the test dataset, the best flyrock predictive model was found to be the GP based model, with R2 = 0.908, RMSE = 17.638 and VAF = 89.917, while the corresponding values for R2, RMSE and VAF for the NLMR model were 0.816, 26.194, and 81.041, respectively.

Particle swarm optimization approach for forecasting backbreak induced by bench blasting

One of the most challenging safety problems in open pit mines is backbreak during blasting operation, and its prediction is very important for a technically and economically successful mining operation. This paper presents application of particle swarm optimization (PSO) technique to estimate the backbreak induced by bench blasting, based on major controllable blasting parameters. Two forms of PSO models, linear and quadratic, are developed based on blasting data from Sungun copper mine, Iran. According to obtained results, both models can be used to predict the backbreak, but the comparison of two models, in terms of statistical performance indices, shows that the quadratic form provides better results than the linear form.

Автоматизация оперативного управления доменным процессом с использованием модельно-упреждающего подхода

Blast furnace operational management automation using modelling and real-time predictive solutions for the object control are considered. Main features of the proposed control are: using of an operational data mining software to identify effective clusters of the furnace regime parameters values; real-time software for identification of the furnace cohesion zone parameters for the operational management correction; dynamics forecasting of the furnace thermal state indicators when charge load and blast parameters change. Usage of the software permits to achieve effective values of the furnace regime parameters with high productivity and reduced coke consumption. It is effective in conditions of the significant charge parameters changes, due to using of source materials from different suppliers. Therewith, forecasting of parameters dynamics allows supervisor to stabilize the blast furnace process in the effective regime. The system is based a joint development of the South Ural State University (National Research University), "Polytech-Automatica" Research & Production Ltd. (Chelyabinsk) and "AKOMM" Ltd. (Moscow).

Machining of Hygroscopic Materials by High-pressure CO2 Jet Cutting

Cutting with a high-pressure CO2 jet has the potential for a dry and residue-free machining of hygroscopic materials. An experimental system for continuous CO2 high-pressure jets at atmospheric conditions was developed. The high-pressure liquid CO2 expands into atmospheric pressure after exiting the nozzle and changes to gas and particles and can be used for the machining of parts and surfaces. The investigations led to first expertises for the continuous jet cutting with high pressure CO2 at atmospheric conditions with jet pressures of up to 3000bar. Commercial blasting plants are not available yet and only research institutes hold prototypes and experimental systems. During the technological examinations the mass flow and impulse forces of CO2 and high-pressure water jets were determined and compared experimentally. Identical cutting tests were carried out with polyurethane. Principal similarities are shown in the produced cutting surfaces and grooves of both processes. The experiments indicated that the effects of the individual blasting parameters are identical to the impulse force and groove depth for both processes. The high-pressure CO2 jet offers a dry and residue-free machining of hygroscopic materials. The process can be integrated decentralized and directly into production lines. According to the current knowledge, the limitation for the cutting of materials, depending on the thickness of the workpiece, is a maximum hardness of 60 Shore D at a maximum density of 600 g/cm3. Thus, the process is currently limited to the processing of synthetic and natural materials.

Finite Element and Experimental Analyses of an Armoured Vehicle Subjected to Landmine Blast

Landmines severely threaten the armoured vehicles. The principal objective is to present a methodology for blast simulations of vehicles subjected to landmine explosions. First, free field blast experiment of 2 kg TNT charge in a steel pot is carried out to validate the blast parameters used in the numerical simulation. Overpressure-time history collected in the free field blast experiment is compared to the numerical simulation results. Numerical simulations are performed in LS-DYNA hydrocode that employs Arbitrary Lagrangian Eulerian formulation enabling a fully coupled interaction between the blast wave, the detonation gases, and the vehicle. Second, the full-scale field test of an armoured vehicle exposed to 6 kg of TNT charge in a steel pot underneath the rear end of the vehicle is conducted. Maximum dynamic deformations measured inside the vehicle are compared to the results calculated in the numerical simulation. Results show that the numerical simulation is in good agreement with the full-scale field test.

Mechanization of the Grit Blasting Process for Thermal Spray Coating Applications: A Parameter Study

The bond strength between a thermal spray coating and substrate is critical for many applications and is dependent on good substrate surface preparation and optimized spray parameters. While spray parameters are usually carefully monitored and controlled, most surface preparation is carried out by manual grit blasting, with little or no calibration of blast parameters. Blasting is currently highly dependent on operator skill and often surface finish is only assessed visually, meaning a consistent, reproducible surface profile cannot be guaranteed. This paper presents investigations on the effect of blast parameters (including blast pressure, standoff distance, media feed rate, blast angle, traverse speed, and media size) on surface profile for seven different metallic substrates using a mechanized, robotic blasting system and employing a brown fused alumina blast medium. Substrates were characterized using non-contact focus variation microscopy. Average surface roughness was found to be most affected by blast pressure, media size, and traverse speed, while changes to media feed rate and standoff distance had a limited effect on surface profile. Changes to blast angle resulted in limited change to average roughness, but microscopy examinations suggested a change in the mechanism of material removal.

DEVELOPMENT OF INFORMATION-LOGICAL SYSTEM OF RECOGNITION OF DEVIATIONS FOR BLAST FURNACE PRODUCTION FROM NORMAL MODE

Abstract. The article presents the development of information-logical system that allows the recognition of blast furnace deviation kinds from the normal mode. The effect of melting course parameters of blast furnace at the risk of deviations from normal operation has been investigated. A functional model of information system, consisting of 94 decomposed blocks, as well as a three-component extensible, scalable software architecture, consisting of a unit of work with databases, mathematical libraries and a graphical user interface have been developed. The resulting software allows detecting operatively the presence of deviations from the normal course of melting, determining its type on the actual data of the operation furnace and taking actions to eliminate these deviations. The functionality of the software and the results of the tests for managing blast furnace at JSC “Magnitogorsk iron and steel works” were described.

Exergy loss minimization for a blast furnace with comparative analyses for energy flows and exergy flows

An optimization model based on material balance and energy balance for a blast furnace iron-making process is established, in which exergy loss minimization is taken as optimization objective. Optimization results are obtained by using sequential quadratic programming method. Effects of coal ratio, top gas temperature, slag basicity and blast parameters on the optimization results are analyzed. The optimization results of the exergy loss minimization objective and the coke ratio minimization objective are analyzed comparatively. The energy flows and exergy flows before and after the optimizations for different objectives are analyzed comparatively. The results show that the total energy flow input, the total exergy flow input and the exergy loss decrease after optimizations. The exergy loss obtained from the optimizations for the exergy loss minimization objective and coke ratio minimization objective decreases by 5.77% and 5.14%, respectively. Above 80% of the total energy input is the energy of fuel and above 80% of the total exergy input is the exergy of fuel. The exergy loss decreases with the increases in coal ratio and blast temperature, and increases with the increases in blast humidity, oxygen enrichment, top gas temperature and slag basicity.

Observations from Preliminary Experiments on Spatial and Temporal Pressure Measurements from Near-Field Free Air Explosions

It is self-evident that a crucial step in analysing the performance of protective structures is to be able to accurately quantify the blast load arising from a high explosive detonation. For structures located near to the source of a high explosive detonation, the resulting pressure is extremely high in magnitude and highly non-uniform over the face of the target. There exists very little direct measurement of blast parameters in the near-field, mainly attributed to the lack of instrumentation sufficiently robust to survive extreme loading events yet sensitive enough to capture salient features of the blast. Instead literature guidance is informed largely by early numerical analyses and parametric studies. Furthermore, the lack of an accurate, reliable data set has prevented subsequent numerical analyses from being validated against experimental trials. This paper presents an experimental methodology that has been developed in part to enable such experimental data to be gathered. The experimental apparatus comprises an array of Hopkinson pressure bars, fitted through holes in a target, with the loaded faces of the bars flush with the target face. Thus, the bars are exposed to the normally or obliquely reflected shocks from the impingement of the blast wave with the target. Pressure-time recordings are presented along with associated Arbitary-Langrangian-Eulerian modelling using the LS-DYNA explicit numerical code. Experimental results are corrected for the effects of dispersion of the propagating waves in the pressure bars, enabling accurate characterisation of the peak pressures and impulses from these loadings. The combined results are used to make comments on the mechanism of the pressure load for very near-field blast events.

Software for the Raw-Materials Management System in Blast-Furnace Smelting

A description is presented of an information-modeling system developed to help optimize the composition of the charge materials and fluxes in sintering and blast-furnace smelting. The system is based on models that provide for end-to-end accounting of the sintering-machine and blast-furnace charges, calculate the technical-economic indices of blast-furnace smelting (coke rate, productivity) when there are changes in the blast parameters, the properties of the coke, and the composition of the iron-ore-bearing part of the charge, calculate the properties of the primary and secondary slags and the desulfurizing ability of the final slag, predict the sulfur content of the pig iron; model the gasdynamic regime during smelting, and diagnose the course of the smelting operation. The software that has been developed is designed to automate the work station of production personnel in the blast-furnace shop at the Magnitogorsk Metallurgical Combine.

Thermobaric and Enhanced Blast Explosives – Properties and Testing Methods

AbstractThe review of the available literature on thermobaric explosives and enhanced blast explosives (high‐destructive explosives) is done in the paper. These types of explosives are defined, their common features and differences are shown. Special attention is paid to the physical phenomena accompanying the process of explosion of such fuel‐enriched heterogeneous explosives. These materials are divided into liquid and solid mixtures and composite materials, including layered charges. The considered explosives are characterized in details, methods of determination of their blast parameters are discussed and the results of experimental tests are presented.

TECHNOLOGICAL FEATURES AND SOFTWARE CALCULATIONS OF BLOWING CHARGE IN BLAST FURNACE

The article presents the technological features of the charge choice for fi lling the blast furnace. The developed complex of mathematical models and software was designed for charge calculation to fi ll the blast furnace with adjustable process of slag formation and recovery. When blowing, the fi rst portions of slag-forming and iron-ore materials were located in the furnace shaft and there was no need for gradual improvement of the ore load. The basic functional capabilities of the software allowed the following: manual maintenance (the structural characteristics of blast furnaces; the parameters of the previous blowing-in, properties of slag-forming and iron ore materials, coke, and others); the calculation of the charge for fi lling and cast iron and slag properties at user-specifi ed spending of slag-forming materials and fl uxes and blast parameters; calculation of the optimal charge composition for fi lling and blowing selection subject to the restrictions in heat, slag, gas-dynamic regimes and the quality of the cast iron; diagnosis and presentation of calculation results in tabular and graphical forms, saving them in the database.

Analysis of key technologies and development of integrated digital processing system for cast blasting design

Casting blast can greatly reduce the stripping cost and improve the production capacity of opencast coal mines. Key technologies including high bench blasting, inclined hole, millisecond blasting, pre-splitting blasting and casting blast parameters determination which have influence on the effect of casting blast have been researched with the combination of the ballistic theory and experience in mines. The integrated digital processing system of casting blast was developed in order to simplify the design process of casting blast, improve working efficiency and veracity of design result and comprehensively adopt the software programming method and the theory of casting blast. This system has achieved five functions, namely, the 3D visualization graphics management, the intelligent management of geological information, the intelligent design of casting blast, the analysis and prediction of the blasting effect and the automatic output of the design results. Long-term application in opencast coal mines has shown that research results can not only reduce the specific explosive consumption and improve the blasting effect, but also have high value of popularization and application.

Rational parameters of blasting, considering action time of explosion-generated pulse

The developed pattern of calculation for the parameters of drilling and blasting in boreholes and shotholes is based on a charge design with reduced amount of explosive at the top. The calculation takes into account the action time of the explosion-generated pulse conditioned by outflow of detonation product gases. The authors have derived relations for such rational parameters of drilling and blasting that minimize costs of drilling at the same quality of rock fragmentation.

Angle of Incidence Effects on Far-Field Positive and Negative Phase Blast Parameters

The blast overpressure acting on a rigid target is known to vary between the normally reflected overpressure and the incident overpressure as a function of the angle between the target and the direction of travel of the blast wave. Literature guidance for determining the exact effects of angle of incidence are unclear, particularly when considering the negative phase. This paper presents the results from a series of well controlled experiments where pressure transducers are used to record the pressure-time history acting on the face of a large, rigid target at various angles of incidence for varying sizes of hemispherical PE4 charge and stand-off distances. The test data demonstrated remarkable repeatability, and excellent agreement with semi-empirical predictions for normally reflected overpressures. The oblique results show that peak overpressure, impulse and duration are highly dependent on angle of incidence for the positive phase, and are invariant of angle of incidence for the negative phase.

Software for the selection of blast-furnace batch

The selection of blast-furnace batch is considered. Software is developed for the calculation of the blast-furnace batch in forced startup (with controllable slag formation and reduction). In this approach, the first portion of slag-forming mixture and iron ore is introduced in the furnace shaft, and there is no need for gradual increase in the ore load. The software permits the compilation of reference material (the design characteristics of the blast furnaces, the parameters of preceding melts, the properties of the slag-forming mixture and iron ore, the properties of the coke, etc.); calculation of the batch composition and the properties of the hot metal and slag with specified additions of slag-forming mixture and fluxes and specified blast parameters; calculation of the optimal batch composition and selection of the blast parameters within the constraints on the thermal, slag, and gas-dynamic parameters and the quality of the hot metal produced; diagnostics; and presentation of the calculation results in tabular and graphical form, with subsequent storage in a database.

Mitigation of rock burst events by blasting techniques during deep-tunnel excavation

The buried depths of the auxiliary tunnels of the Jin-ping II Hydropower Station in China are between 1500m and 2300m, and some violent rock bursts were encountered during the excavation process. The measures of rock burst prevention adopted at this station are summarized in this paper, and the mechanisms of these measures are studied and discussed. Combined with the monitoring of the in-situ stress state and the burst proneness of surrounding rocks, the spatial distribution of the rock bursts along the deep tunnel axes and the statistics of rock bursts around the blasting working face are studied. It lays the foundation for generating the strategies for rock burst prevention. The results indicate that the development of rock bursts depends primarily on the level of in-situ stress and on the brittleness of rocks. Disturbances from excavation particularly under blasting excavation conditions have an important influence on the intensity and the scale of rock bursts. Therefore, two primary guidelines for controlled blasting are followed to control rock bursts. One is to decrease stress of the surrounding rocks; the other is to control the disturbance from the excavation. First, the stress-relief blasting method is adopted to reduce the stiffness of the surrounding rocks and reduce the concentration of stress in the blast area. Two different stress-relief blasting design schemes are applied and the extent of the damage and stress relieving effects are compared. Second, the effects of the blasting excavation disturbance in high-stressed rocks are examined. The results indicate that reducing the excavation footage can be used to control the blasting excavation disturbance in deep tunnels. The energy release rate (ERR) for different excavation footages is simulated to verify this conclusion. After the proper excavation footage and perimeter blasting parameters are adopted, the method is applicable to the control of blasting excavation and the reduction of rock burst intensity in engineering practices.

Blast wave parameters at diminished ambient pressure

Relation between blast wave parameters resulted from a condensed high explosive (HE) charge detonation and a surrounding gas (air) pressure has been studied. Blast wave pressure and impulse differences at compression and rarefaction phases, which traditionally determine damage explosive effect, has been analyzed. An initial pressure effect on a post-explosion quasi-static component of the blast load has been investigated. The analysis is based on empirical relations between blast parameters and non-dimensional similarity criteria. The results can be directly applied to flying vehicle (aircraft or spacecraft) blast safety analysis.

English

The unconfined aerosols of propylene oxide (PO) are formed by dispersing the fuel in air. These aerosols undergo detonation by suitable initiation and produce high impulse blast. Tri-nitro Toluene (TNT) equivalence is an important parameter used to represent the power of explosive materials and compare their relative damage effects wrt TNT. The parameters commonly used for estimation of TNT equivalency are total energy of explosive source and properties of resulting blast wave, viz., blast peak overpressure and positive impulse. In the present study, the unconfined aerosols of 4.2 kg PO were formed by breaking open the cylindrical canister with the help of axially positioned central burster charge and then detonated using a secondary explosive charge after a preset time delay. The resulting blast profiles were recorded and the blast parameters were analysed. Being a non-ideal explosive source, the TNT equivalency depends on fraction of total energy utilised for blast formation, the rate of energy release, cloud dimensions, and concentration of fuel. Hence, various approaches based on energy release, experimental blast profiles, triangulated blast parameters, and ground reflected blast parameters were considered to determine the TNT equivalency of unconfined PO aerosols. It was observed that the TNT equivalency is not a single value but vary with distance. The paper provides various options for weapon designer to choose a suitable approach for considering TNT equivalency. The scaling laws established from the experimental data of unconfined aerosols of PO for blast peak over pressure and scaled impulse help in predicting the performance for different values of fuel weight and distance. Defence Science Journal, Vol. 64, No. 5, September 2014, pp.431-437, DOI:http://dx.doi.org/10.14429/dsj.64.6851