Methane emissions from the mines belonging to the Hunedoara Energy Complex

Methane emitted by the hard coal mines in operation in the Jiu Valley coalfield is under study in order to find out the most suitable solutions that increase occupational health and safety and at last, but not in the least, to capitalize the power generating potential of it. From the point of view of occupational safety, methane displays the highest risk because it can give birth to an explosive mixture with the air and the coal dust. Methane discharges into the outer atmosphere have a negative impact, increasing the greenhouse effect, with serious consequences over the parameters of the climate. This paper focuses on the use of mine gas in three important stages: solutions for the use of methane discharged by central degassing stations for power generating purposes; development of the network for the drainage of gases and increasing the volume of recovered methane; solutions for the use of CH4 from the general ventilation.

Use of Gas Emulsion in Blasting Project for Clearing in a Copper Mine in Southern Peru

The gasifiable emulsion is a technological and productive response to the need to reduce operating costs in the mining project, among the improvements with respect to ANFO are a higher detonation velocity (VOD), better fragmentation and reduction of nitrous fumes. In the test mining operation, a commercial explosive mixture called "Q "73 (70% emulsion and 30% ANFO) is used, where the ANFO is composed of 97% ammonium nitrate and 3% diesel, and the explosive mixture "Q "82 (80% emulsion and 20% ANFO) is also used, 7 blasting processes were carried out with a diameter of 12.25 in. in a waste area, the most characteristic rocks found in the blasting project in the copper mine in southern Peru are Toba Cristal (TC), Andesite Basaltic Propylitic (BA-PRO), Andesite Basaltic Argillic (BA-ARG). The results obtained show a reduction of the Power Factor by 1.32%, with respect to the commercial mixtures "Q "73 and "Q "82 an optimum increase in the detonation velocity of 9.92% and 0.59% was obtained, also the high-resolution images of the fumes after blasting indicate a low presence of orange fumes taking a great relevance in the mining sector on a large scale, achieving better results in the blasting phase.

Self-Acting Formation of an ANFO Similar Type of Explosive under Fire Conditions: A Case Study

On 2 October 2003 in Saint-Romain-en-Jarez (France) a fire in a farm building triggered an explosion in which 26 people were injured. Police investigation, based solely on an analysis of the effects and on general engineering knowledge, showed that the explosion was caused by an uncontrollably generated mixture of ammonium nitrate (AN) and molten plastic crates which formed an explosive mixture similar to ammonium nitrate fuel oil (ANFO). This is the only commonly known example of an ammonium nitrate blast taking place at its end user destination. Is such an explanation of the incident plausible and could a similar blast possibly happen anywhere else? The experimental results support this thesis of French investigators but raise further doubts. Laboratory reconstruction of the self-acting process of generating the explosive material confirmed the investigators’ report. However, other materials at the incident site could have influenced the final outcome too. The lab-recreated explosion of a mixture of AN and molten plastic partially confirmed the report’s thesis.

Aspects of laboratory tests for the determination of the minimum ignition energy of the fuel / dust mixture

During the technological processes of processing, production, handling and storage of combustible dusts, complex explosive mixtures may occur, the characteristics of which, in most cases, cannot be assimilated with the existing data in the specialized literature. If these combustible dusts are mixed with air in appropriate proportions and are initiated by an efficient source of ignition, they can burn rapidly and with considerable explosive force. One of the most common sources of ignition of potentially explosive atmospheres generated by the dust / air mixture is static electricity, materialized by electrostatic discharges. In order to assess the risk of ignition of an explosive mixture of air / dust, it is necessary to know the sensitivity of the explosive atmosphere to ignition, ie the value of the minimum ignition energy of the explosive mixture, which is then compared with the energy resulting from an electrostatic discharge. The paper presents a comparative analysis regarding the methods of determining the minimum ignition energy for air / fuel dust mixtures, using different devices, on the same type of dust.

Evaluation of the explosion risk specific to the preparation and storage activity of the simple explosive mixture type ANFO

The paper presents the results of the theoretical and practical research regarding the evaluation of the explosion risk specific to the activity of preparation/storage activity of the ANFO type explosive mixture, based on the identification and systematic analysis of the potential dangers that can generate explosion events, in order to establish and substantiate the possible accidents main scenarios, as well as reference scenarios. From a structural point of view, each accident scenario, defined at the level of the industrial site analyzed, is configured procedurally in synthetic form, comprising typical sections of methodological approach, respectively: location, description of the consequences (unimportant, important), evaluation of the risk of explosion (identification, estimation and appreciation) and measures to prevent damage/measures to reduce the risk of explosion.

Research in the field of evaluation of anfo explosive preparation installations, Tests and results

The technical-economic efficiency of rock extraction works depends significantly on the drilling and blasting works as well as the adjacent costs. The cost of the explosive is an important component in these and the generalization of the widespread use of the use of bulk explosives (ANFO) has generated a significant reduction in the cost. Making the explosive close to the place of use in fixed or semi-stationary installations on the quarry stage eliminates the costs related to storage or long-term storage, transport, escort, security. However, installations for the manufacture of ANFO type explosives must consistently produce a simple quality explosive mixture. The quality lies in the participation of the precursors as well as in the degree of homogenization, stability and a good behavior to external stimuli that can lead to sensibility to initiation stimuli or inhibition of sensitivity where the harmful influence of moisture in the raw material or environment must be emphasized. The paper presents tests and results obtained in recent years for such installations used by several companies in Romania performed under the supervision of INSEMEX specialists. These assessments were completed with the certification of explosives manufacturing facilities for the specified operating parameters as well as for explosives.

Tropical Wood Dusts—Granulometry, Morfology and Ignition Temperature

The article considers the granulometric analysis of selected samples of tropical wood dust from cumaru (Dipteryx odorata), padauk (Pterocarpus soyauxii), ebony (Diospyros crassiflora), and marblewood (Marmaroxylon racemosum) using a Makita 9556CR 1400 W grinder and K36 sandpaper, for the purpose of selecting the percentages of the various fractions (<63; 63; 71; 200; 315; 500 μm) of wood dust samples. Tropical wood dust samples were made using a hand orbital sander Makita 9556CR 1400 W, and sized using the automatic mesh vibratory sieve machine Retsch AS 200 control. Most dust particles (between 50–79%) from all wood samples were under 100 μm in size. This higher percentage is associated with the risk of inhaling the dust, causing damage to the respiratory system, and the risk of a dust-air explosive mixture. Results of granulometric fractions contribution of tropical woods sanding dust were similar. Ignition temperature was changed by particle sizes, and decreased with a decrease in particle sizes. We found that marblewood has the highest minimum ignition temperature (400–420 °C), and padauk has the lowest (370–390 °C).

Adriaan Koerbagh, “An Excellent Mathematician but a Wicked Fellow”

In the spirit of the new naturalism, Adriaan Koerbagh defends in Een Ligt schijnende in duystere plaatsen (1668) the freedom to philosophize with a fundamental critique of religion and metaphysics. He links this criticism to the politically radical, anti-hierarchical idea of universal equality and freedom. Moreover, by writing in Dutch, he addresses a broad audience with this explosive mixture of ideas. At the very center of his naturalism is the idea of an indifferent God or nature. He criticizes, unmasks, and translates improper language that is aimed at deception and oppression, and leads to violence. His loanword dictionary Een Bloemhof van allerley lieflijkheyd sonder verdriet (1668) can be seen as the preparatory handwork to this critical project. Koerbagh thereby places himself in the line of the clandestine freethinkers such as Vanini, the anonymous authors of Theophrastus redivivus and De jure ecclesiasticorum, Spinoza, and the clandestine text written ‘in the spirit of Spinoza,’ Traité des trois imposteurs. I will illustrate this genealogical line and thus illuminate the significance of this (politically) subversive thinker for the radical Enlightenment.

Aluminum-to-Steel Cladding by Explosive Welding

The production of aluminum-carbon steel and aluminum-stainless steel clads is challenging, and explosive welding is one of the most suitable processes to achieve them. The present work aims to investigate the coupled effect of two strategies for optimizing the production of these clads by explosive welding: the use of a low-density interlayer and the use of a low-density and low-detonation velocity explosive mixture. A broad range of techniques was used to characterize the microstructural and the mechanical properties of the welds, specifically, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, microhardness and tensile-shear testing with digital image correlation analysis. Although aluminum-carbon steel and aluminum-stainless steel have different weldabilities, clads with sound microstructure and good mechanical behavior were achieved for both combinations. These results were associated with the low values of collision point and impact velocities provided by the tested explosive mixture, which made the weldability difference between these combinations less significant. The successful testing of this explosive mixture indicates that it is suitable to be used for welding very thin flyers and/or dissimilar materials that easily form intermetallic phases.