Re-Use of Silico-Manganese Slag

The world’s rapidly growing demand for raw manganese has made it increasingly important to develop methods for the economic recovery of manganese from secondary sources. The current study aims to present possible ways for the recycling and reuse of silico-manganese slag landfilled in Tulcea, City on the Danube River close to the Danube Delta Biosphere Reserve in order to save the natural resources raw of manganese. In the last three decades, the ferroalloy production plant has over 2.6 million tons of slag. Slag dumping constitutes a significant source of air, water and soil pollution, which adversely affects the environment and human health. Mn present in the slag dump is an environmental pollutant with potentially toxic effects. The results obtained with a leaching method to recover manganese from slag shows two efficient ways to valorize manganese from solid fraction (54%) with size particles between 80 and 315 µm and/or reuse the leaching medium (56% Mn) with a slag size of <80 µm. The motivation of our research is the possibility to recover manganese from slag by saving natural resources of raw of manganese and the remaining fraction can be used as aggregate sources (construction and road rehabilitation by saving extract mineral aggregates and agriculture), in order to decommission the slag dump. The proposed research is in concordance with the sustainable use of natural resources for the achievement of sustainable development of the 2030 Agenda and Waste Management Legislation due of the huge ecological costs regarding non-conforming waste dumping. If we consider the cost-benefit analysis, the environmental future is more important the human health and the benefits on the quality of the population’s health and the environment which are not non-measurable in monetary value.

Oxidation-Enhanced Evaporation in High-Carbon Ferromanganese

Thermal fume formation is a problem in manganese ferroalloy production and the metal production industry at large. A better understanding of the mechanisms of fume formation and the operational parameters affecting the fume formation rate may help in reducing and managing fuming. This paper aims to investigate the effects of oxygen content and gas flow rate on the fuming rate and fume particulate properties for liquid high-carbon ferromanganese. The fuming rates were attained experimentally by measuring the fume flux with respect to oxygen content and gas velocity above the metal melt. The generated fumes were also characterized in terms of particle size and element distribution between fume and melt. The fuming rates were found to steadily increase with increasing oxygen content and flow rate of the gas up to a point where the curve flattens, following theoretical predictions. However, the highest flux values measured were above the theoretical limitations of the evaporation flux in vacuo given the alloy bulk composition. It is hypothesized that the high rate of fuming is caused by an increased manganese activity at the alloy surface due to local decarburization of the alloy in contact with the oxidizing gas. Graphical Abstract

Water content and metal pollution dynamics in the surface layer of urban soils: first results of the PROFILES project

&lt;p&gt;This work presents the first results obtained in the context of the PROFILES project. The main objective of PROFILES concerns the identification of a possible correlation between water content dynamics and the distribution of metal pollutants in the surface layer of urban soils.&lt;/p&gt;&lt;p&gt;The research activity combined experimental, analytical and numerical approaches. Field activity was conducted in Bagnolo Mella, (Brescia, Northern Italy) where a ferroalloy industry operated for more than forty years (1974-2015). Four sites within the study area, at different radial distances and up/downwind with respect to the plant, have been considered. At these sites, the distribution of As, Cu, Fe, Mn, Ni, Pb, Zn concentrations in the surface soil was inferred by means of a portable X-Ray Fluorescence device. A tension infiltrometer allowed to estimate the local value of hydraulic conductivity at saturation, K&lt;sub&gt;s&lt;/sub&gt;. Physico-chemical properties evaluated on soil samples via laboratory analysis were found to be rather homogeneous. However, metal concentrations were remarkably different at the four sites, larger values being detected up-wind and closer to the production plant, within the top layer (&amp;#8776; 20 cm) of the soil column. In particular, sequential chemical extraction processes and X-ray Absorption Near Edge Spectroscopy showed that Mn exceeded considerably typical background levels and was present in a hybrid form of magnetite (Fe, Mn)&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt;, resistant to acid dissolution. Considering that it is difficult to form Mn-substituted magnetite in surface layers at low temperatures, its presence indicates this pollutant as a by-product of ferroalloy production transported by water along the soil column. Numerical simulations with the HYDRUS 1D software have been performed to model water dynamics along the uppermost 6 meters of soil at the investigated sites, over a time range of 4 years (2013&amp;#8211;2016). A homogeneous domain, with a constant K&lt;sub&gt;s&lt;/sub&gt; value measured in the field for the top layer, has been compared against a heterogeneous case, in which the distribution of lithological categories has been determined via indicator kriging, based on available stratigraphic data. Surface recharge and evapotranspiration have been estimated from meteorological data (temperature, relative humidity, precipitation, global solar radiation and wind speed) available on an hourly basis. Numerical results allowed to characterize the time evolution of the zero-flux-plane (ZFP) depth, defined as the plane separating zones with upward and downward water flux in a thoroughly wetted soil, when evaporation and drainage are simultaneously occurring. Key findings are: (i) for the whole simulated period, the ZFP oscillates between the ground surface and a maximum depth of about 20 cm, consistent with the vertical range where peak concentrations of heavy metals were found; (ii) simulations in the homogeneous and heterogeneous cases provided analogous results, highlighting the importance of the characterization of the top surface layer.&amp;#160;&lt;/p&gt;&lt;p&gt;Acknowledgments: The project PROFILES was awarded the 2019 edition of the Florisa Melone Award, promoted by the Italian Hydrological Society (SII). The authors thank the SII for the support. Part of the research was carried out within the ISEIA project of the University of Brescia (grant UNBSCLE 9015).&lt;/p&gt;

Densification of Biocarbon and Its Effect on CO2 Reactivity

Charcoal is an interesting reducing agent because it is produced from biomass which is renewable and does not contribute to global warming, provided that there is a balance between the felling of timber and growth of trees. Biocarbon is a promising alternative to fossil reductants for reducing greenhouse gas emissions and increasing sustainability of the metallurgical industry. In comparison to conventional reductants (i.e., petroleum coke, coal and metallurgical coke), charcoal has a low density, low mechanical properties and high CO2 reactivity, which are undesirable in ferroalloy production. Densification is an efficient way to upgrade biocarbon and improve its undesirable properties. In this study, the deposition of carbon from methane on three types of charcoal has been investigated at 1100 °C. CO2 reactivity, porosity and density of untreated and densified charcoal were measured, and results were compared to metallurgical coke. Surface morphology of the charcoal samples was investigated by using scanning electron microscopy (SEM). SEM confirmed the presence of a deposited carbon layer on the charcoal. It was found that the CO2 reactivity and porosity of charcoals decreased during the densification process, approaching that of fossil fuel reductants. However, the CO2 reactivity kept higher than that of metallurgical coke.

The Using of Technogenic Waste from Ferroalloy Production

When ferroalloys are produced, a large number of coproducts are also formed: slag, riddlings of small fractions of ore raw materials and finished products (ferroalloys), sludge, dust and a number of other materials. Their use and processing allows for reduced consumption of the original minerals, thereby increasing the efficiency of the main production and reducing environmental pollution. As a result, both enterprise costs in the form of environmental payments for emissions and waste disposal, as well as government costs associated with environmental measures are reduced. However, the scale of use of ferroalloy production wastes is relatively small. The replacement of the main and auxiliary equipment with new, environmentally friendly equipment, can promote to significantly reduce or completely eliminate hazardous emissions and the generation of unclaimed production waste. It is necessary to organize the use of blast furnace gas from ore reduction furnaces for preheating and partial recovery of elements of charge materials. Keywords: waste, ferroalloy production, utilization

The Waste of the Ferroalloy Production in Russia

Ferroalloys are used to change the composition and properties of ferrous and non- ferrous metals. Therefore, the volume of ferroalloy smelting corresponds to the amount of steel and other alloys produced. Currently world steel production is approximately 1630 million tons, and about 40 million tons of various ferroalloys are produced (2.5%). The structure of ferroalloy production in different countries mainly depends not on the needs of industrial enterprises, but on ore reserves. Excessive amounts of ferroalloys produced are exported, and the missing alloys are imported. In Russia silicon alloys that have no restrictions in the raw material base (44%) are the most produced, then manganese (25%) and chromium (23%) ferroalloys. The remaining ferroalloys account for 8% of production. About half of the manganese ferroalloys needed for consumption are bought abroad, and half are produced in the Russian Federation from foreign raw materials (Kazakhstan, South Africa, Gabon). The Russian Federation provides itself with chromium ferroalloys completely, and sells ∼ 80%, and for their production mainly imported raw materials (∼ 65%) from Kazakhstan are used. Keywords: ferroalloy, ferrochrome, slags, production of ferroalloy

Development of composition and process of obtaining multicomponent ferroalloys

The main product of ferroalloy plants is standard ferroalloys. They often do not have all the necessary service characteristics and are not very suitable for metal processing in a ladle. The developing progressive technology of steelmaking is forced to adapt to the existing range of ferroalloys, the standards for which have not been updated for 50 years or more. In addition, in recent years, the sources and markets of ferroalloy raw materials have changed, and their quality and content of leading elements have decreased. This makes it difficult or excludes the possibility of obtaining ferroalloys according to existing standards. In this regard, the production of more efficient ferroalloys of a new generation is required, suitable for progressive processes in the developing areas of ferrous and non-ferrous metallurgy 795 and smelted from non-traditional types of domestic ore raw materials. These include complex or multicomponent ferroalloys containing, in addition to iron, two or more functional elements. Complex ferroalloys should be created in the most favorable combinations of component. It contributes to the necessary effective impact on the iron-carbon melt with a high degree of assimilation of useful elements in it. The creation of scientific foundations for the formation of new compositions of multicomponent ferroalloys with high consumer properties, and the development of physicochemical processes for obtaining these alloys from unconventional ore raw materials contributes to solving the problems of developing compositions of effective new generation ferroalloys and expanding the ore base of ferroalloy production. When using the developed method of designing the composition of complex ferroalloys using unconventional raw materials, melting technologies were developed; various alloys of the systems were obtained and applied on a laboratory and industrial scale: Fe – Si – Cr, Fe – Si – B, Fe – Si – Ba – Ca, Fe – Si – Al – Nb, Fe – Si – Ca – Mg, Fe – Si – V – Ca – Mn, Fe – Si – Al.