Indirect estimate of in loco moisture via normative mineralogy calculation with correction of seasonal effect on itabirite (banded iron formation) of the Pico complex, Quadrilátero Ferrífero, Minas Gerais, Brazil

Moisture is a critical variable in iron-ore processing, handling and transportation. During beneficiation, excessive moisture may lead to screen and chute clogging. In transportation, moisture values above transportable moisture limit may cause cargo instabilities, especially in regard to vessels. Moisture is a non-stationary variable that depends on spatial and time distributions. Therefore, classical estimate methods such as ordinary kriging are not appropriate to calculate moisture values. Here, we present an extension of the Normative Mineralogy Calculation to indirectly estimate moisture, considering seasonal influence. This study in based on three iron-ore mines, Galinheiro, Pico and Sapecado. They are located in the Quadrilátero Ferrífero of Minas Gerais, Brazil, a world-class iron-ore district. The method proposed herein provides useful information that can be applied elsewhere. Our results indicate that compact ores show low moisture values with little seasonal influence, while soft ores and canga (iron-rich duricrust) are strongly influenced seasonally due to higher porosity and greater capacity of retaining water in the crystal structure of minerals, such as goethite. Moisture variations may exceed 2% along the year. Such variations are enough to preclude the beneficiation of certain iron ores during the rainy season. For this reason, moisture has been regarded as an essential variable in short-term mining. Article Highlights Moisture is a critical variable in iron-ore processing, handling and transportation. Moisture depends on spatial and time distributions; hence classical methods are not appropriate to quantitatively estimate it. This study proposes an indirectly estimate of moisture considering seasonal influence. Compact iron ores are little influenced seasonally, while soft iron ores and canga (duricrust) are strongly affected by the rainy season due to their higher porosity and greater capacity of retaining water. The seasonal effect on moisture is an essential variable that must be consider to better effectiveness of iron-ore mining sequencing and beneficiation.

Technical and economic indicators of a slurry tailings hydrotransport system when replacing steel slurry lines with polyurethane-coated slurry lines

The hydrotransport system of Andrei Varichev Mikhailovsky GOK JSC used for iron ore processing tailings was studied with the aim of establishing its performance when using slurry pipelines with and without polyurethane coatings of their internal surfaces under mass concentration variations of 10 to 70 %. It has been established that the use of internal polyurethane coatings significantly reduces the specific head losses in hydraulic transportation of thickened slurry tailings for iron ore processing tailings. However, the technical and economic calculations performed failed to confirm the economic efficiency of their application for the slurry pipelines of the tailings facility hydrotransport system of Mikhailovsky GOK at any slurry thickening values, due to the significant payback period of capital investments caused by the relatively high current cost of polyurethanecoated pipelines. At the same time, a significant reduction (almost by a factor of four, provided that the current production volumes are maintained) in hydrotransport (energy) costs and maintenance costs of pressure slurry pipelines were identified for a transition to slurry tailings thickening to 50 % solids (excluding the capital and operating costs for the thickening system, reconstruction of the slurry pumping stations and additional measures for the distribution of a thicker slurry at the tailings storage facility). It is proposed to use the results obtained in the reconstruction of the slurry tailings hydrotransport system at the tailings facility of Mikhailovsky GOK with a conversion to hydraulic transportation of bulk concentration tailings thickened to 50 % in ∅820 mm slurry pipelines.

Problems and prospects of involving waste from polymetallic and iron ore processing in biological conservation

Ore enrichment waste is a fine material that poses a serious environmental problem. However, the high residual content of rare and precious metals, as well as valuable metalloids, determines the preservation of technogenic formations as secondary mineral raw materials. This dictates the search for environmentally safe conservation of waste before its subsequent development. This report focuses on reducing the phytotoxicity of waste and the use of bioagumentation - the introduction of exogenous plant matter and azotobacteria into the root layer, which contributes to the optimization of the mineral nutrition of phytoconservants. The article examines the physical and chemical parameters of polymetallic ore dressing waste before and after chemical reclamation, provides information on changes in the composition of watersoluble forms of metal elements (Fe, Mn, Al, Cu, Zn, Cd, Co, Ni), a decrease in the anionic content of the sulfate ion, and the appearance of hydrocarbonates. It is experimentally established that after chemical reclamation of spent slags, their viability for seedlings of oats and white mustard increases. After reclamation, there is an increase in their morphometric indicators. Mustard reacts especially positively to the decrease in acidity and mobility of metals. The dry weight of its seedlings increases-by almost 30% compared to the control. When mustard seeds are inoculated with a suspension of a live culture of the bacterium Azotobacter chroococcum, its roots elongate and their weight increases. It is shown that the growth of mustard roots is also activated on iron ore processing waste that is subject to forest reclamation. But in such conditions, vital azotobacteria exhibit a glow, especially intense in small sand fractions. Chemolumi-nescent reactions ensure the survival of azotobacteria in the development of free radical reactions caused by the residual content of magnetic iron and lignin in the habitat. The revealed features of the growth of oat and mustard seedlings, as well as azotobacteria on ore dressing waste, should be taken into account when developing technologies to increase the biogenicity of the waste surface in vivo, to argue for the use of bioagumentation in creating technologies for environmentally safe waste conservation without involving the fertile soil layer - an irreplaceable natural resource.

Research of resistance to water-jet wear of plastic and steel pipes. Assessment of the main parameters that affect the wear rate of hydraulic transport systems

It has been found that the use of certain types of thermoplastic elastomers as a co-extruded coating of the inner surface of plastic pipe systems can significantly increase the lifetime of pipeline hydrotransport when exposed to hydraulic mixtures, in particular tailings of iron ore processing. The comparison of polyethylene and steel pipes resistance to water-jet wear is made. The influence of the concentration, dispersion, and speed of hydraulic mixtures on the wear rate is estimated.