APPLICATION OF HUMATIC REAGENT FOR DUST DESTRUCTION AND DEGASATION IN MASS EXPLOSIONS

The work is devoted to the coverage of the results of research and industrial tests of environmental efficiency of water replacement in internal and external hydraulic wells in the quarries of mining enterprises for humic reagent [1]. Scientific and technical problem of determining environmental efficiency, solved by conducting in 2020 by the Research Mining Institute (NDGRI KNU) industrial research in the conditions of PJSC "Northern Mining and Processing Plant" (PJSC "PIVNGZK", Kryvyi Rih) kg / dust3 kg rocks) and gas formation (kg / kg BP) during mass explosions with the use of water in the holes in comparison with the use of humic reagent. Dust- binding and degassing properties of humate-based reagents are confirmed by the results of research and industrial tests conducted by the Research Institute of Occupational Safety and Ecology in the Mining and Metallurgical Industry (NDIBPG KNU) in 2019 by conducting experiments with pre-wetting blocks before conditions of quarries of Inguletskyi, Central and Northern GZK [1]. According to the results of experimental and industrial tests, it is substantiated that the efficiency of the use of humic reagent in the external water hammer in comparison with the use of technical water was: dust suppression increases by 20.0%; neutralization of carbon monoxide - 59.4%; neutralization of nitrogen oxides - 55.1%.

Dust destruction at high galactic altitude

The possibility of destruction carbonaceous dust particles swept out by the radiation pressure into near-galactic space due to the relative motion of dust particles of various sizes is considered. The earlier model of the motion of dust in the Galaxy under the action of radiation pressure, gravity, and gas resistance is expanded taking into account the destruction processes. The possibility of dust sweeping is considered taking into account its collisions with the gas of the Galaxy and with other dust particles. Also, we clarify the range of particle sizes that can get into intergalactic space due to the described mechanism.

Revisiting the dust destruction efficiency of supernovae

ABSTRACT Dust destruction by supernovae is one of the main processes removing dust from the interstellar medium (ISM). Estimates of the efficiency of this process, both theoretical and observational, typically assume a shock propagating into a homogeneous medium, whereas the ISM possesses significant substructure in reality. We self-consistently model the dust and gas properties of the shocked ISM in three supernova remnants (SNRs), using X-ray and infrared (IR) data combined with corresponding emission models. Collisional heating by gas with properties derived from X-ray observations produces dust temperatures too high to fit the far-IR fluxes from each SNR. An additional colder dust component is required, which has a minimum mass several orders of magnitude larger than that of the warm dust heated by the X-ray emitting gas. Dust-to-gas mass ratios indicate that the majority of the dust in the X-ray emitting material has been destroyed, while the fraction of surviving dust in the cold component is plausibly close to unity. As the cold component makes up virtually all the total dust mass, destruction time-scales based on homogeneous models, which cannot account for multiple phases of shocked gas and dust, may be significantly overestimating actual dust destruction efficiencies, and subsequently underestimating grain lifetimes.

The role of dust destruction and dust growth in the evolution of the interstellar medium

ABSTRACT We use Milky Way-like chemodynamical simulations with a new treatment for dust destruction and growth to investigate how these two processes affect the properties of the interstellar medium in galaxies. We focus on the role of two specific parameters, namely fdes (a new parameter that determines the fraction of dust destroyed in a single gas particle vicinity of a supernova) and Cs (the probability that a metal atom or ion sticks to the dust grain after colliding, i.e. the sticking coefficient), in regulating the amount and distribution of dust, cold gas and metals in galaxies. We find that simulated galaxies with low fdes and/or high Cs values not only produce more dust, but they also have a shallower correlation between the dust surface density and the total gas surface density, and a steeper correlation between the dust-to-gas ratio and the metallicity. Only for values of fdes between 0.01 and 0.02, and of Cs between 0.5 and 1 do our simulations produce an average slope of the dust-to-gas ratio versus metallicity relationship that is consistent with observations. fdes values correspond to a total fraction of dust destroyed by a single supernova ranging between 0.42 and 0.44. Finally, we compare predictions of several simulations (with different star formation recipes, gas fractions, central metallicities, and metallicity gradients) with the spatially resolved M101 galaxy, and conclude that metallicity is the primary driver of the spatial distribution of dust, while the dust-to-gas ratio controls the cold gas distribution, as it regulates the atomc-to-molecular hydrogen conversion rate.

Gas-dust correlations in nearby galaxies: a case study of NGC 3184 and NGC 7793

ABSTRACT The study of gas-dust interactions occurring in the interstellar medium of a galaxy is essential for understanding various physical processes taking place within it. A comparison of such events at different locations corresponding to diverse astrophysical environments provides more insight into the star formation as well as dust destruction conditions and time-scales. We present a case study for two galaxies: NGC 3184 and NGC 7793, which are typical examples of a ‘grand design spiral’ and a ‘flocculent spiral’, respectively. We investigate the gas-dust correlations at various spatially resolved locations within each galaxy, including spiral arms, using archival data. Moreover, we have segregated the neutral gas into wide (warm) and narrow (cold) velocity components to check the correlations with individual dust emission bands. We find a positive correlation between the gas and the dust, with the total atomic gas emission mainly dominated by its warm component in both the galaxies. We also find the dust population in NGC 7793 to have a greater fraction of emission coming from cold and diffuse, larger-sized dust particles as compared to NGC 3184. This nearby galaxy pilot study could serve as a template for similar studies of larger galaxy samples with analogous morphologies.

Galactic dust evolution with rapid dust formation in the interstellar medium due to hypersonic turbulence

ABSTRACT Turbulence can significantly accelerate the growth of dust grains by accretion of molecules. For dust dynamically coupled to the gas, the growth rate scales with the square of the Mach number, which means that the growth time-scale can easily be reduced by more than an order of magnitude. The limiting time-scale is therefore rather the rate of molecular cloud formation, which means that dust production in the interstellar medium can rapidly reach the levels needed to explain the dust masses observed at high redshifts. Thus, turbulence may be the solution to the replenishment problem in models of dust evolution in high-redshift galaxies and explain the dust masses seen at $z$ = 7–8. A simple analytic galactic dust-evolution model is presented, where grain growth nicely compensates for the expected higher rate of dust destruction by supernova shocks. This model is simpler, relies on fewer assumptions and seems to yields a better fit to data derived from observations, compared to previous models of the same type.