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A greenhouse pot experiment was carried out to evaluate the efficiency of arsenic phytoextraction by the fern Pteris vittata growing in arsenic-contaminated soil, with or without the addition of selected rhizobacteria isolated from the polluted site. The bacterial strains were selected for arsenic resistance, the ability to reduce arsenate to arsenite, and the ability to promote plant growth. P. vittata plants were cultivated for 4 months in a contaminated substrate consisting of arsenopyrite cinders and mature compost. Four different experimental conditions were tested: (i) non-inoculated plants; (ii) plants inoculated with the siderophore-producing and arsenate-reducing bacteria Pseudomonas sp. P1III2 and Delftia sp. P2III5 (A); (iii) plants inoculated with the siderophore and indoleacetic acid-producing bacteria Bacillus sp. MPV12, Variovorax sp. P4III4, and Pseudoxanthomonas sp. P4V6 (B), and (iv) plants inoculated with all five bacterial strains (AB). The presence of growth-promoting rhizobacteria increased plant biomass by up to 45% and increased As removal efficiency from 13% without bacteria to 35% in the presence of the mixed inoculum. Molecular analysis confirmed the persistence of the introduced bacterial strains in the soil and resulted in a significant impact on the structure of the bacterial community.

Petcoke cinder is a solid by-product generated during the gasification of petcoke, accounting for three to five percent of the petroleum coke mass. It commonly contains valuable metals such as V, Ni, Al, and Fe, highlighting its potential as a resource for vanadium extraction. Therefore, it may be considered an emerging secondary source of vanadium and other critical metals. The conventional pyro-cum-hydrometallurgical process for vanadium recovery relies on alkali roasting, which is not only energy-intensive but also contributes to greenhouse gas emissions. Given environmental concerns and high energy consumption, this study presents a state-of-the-art, economically feasible, and energy-efficient process for extracting V from petcoke cinders. This paper discusses the acid-leaching method for vanadium extraction from petcoke cinders and examines various parameters, including acid concentration, temperature, process duration, percentage of H2O2, amount of sodium dodecyl sulfate (SDS), and solid-liquid phase ratios. The optimal recovery rate of V, 95.62%, was achieved under the following conditions: 4 M sulfuric acid at 90 °C for three hours, with a solid-liquid ratio of 15%, H2O2 at 20%, and SDS at 6%. Leaching kinetics were investigated using a shrinking surface-controlled model, revealing a reaction order of 1.29 with respect to sulfuric acid concentration. According to the Arrhenius equation, the apparent activation energy of leaching was approximately 27.67 kJ/mol, and the empirical equation representing the acid leaching kinetics of vanadium was established as 1-(1-??)1/3=kt=(9.261×103)[H2SO4]1.2916exp[-27674/RT]T.

Studies have shown that using nonferrous metallurgy waste in the ceramic mixture for the making of roof tiles improves the final product quality; one can use the clayey portion of the zircon-ilmenite ore gravity tailings as the clay, pyrite cinders as leaners and sintering intensifier, and wollastonite as an agent to reduce shrinkage and prevent deformation-related buckling. The common method of linear regression was used to study the dependency of the basic physico-mechanical properties of tiles on how much clay from the zircon-ilmenite ore gravity tailings, pyrite cinders, and wollastonite is used in manufacture. The resultant mathematical model takes into account the combined effects these components have on the physico-mechanical properties of tiles; it matches well the experimental data.

When obtaining sulfuric acid from pyrite concentrates, a significant amount of waste is generated in the form of pyrite cinders that require disposal. The methods used in processing this raw material are, as a rule, the pyrometallurgical processes of chlorination and chloride sublimation, the disadvantages of which include increased energy consumption and a lack of complexity in the extraction of valuable components. Hydrometallurgical processes are in less demand due to their multi-stage nature and complexity of execution. The method of chemical activation developed at the JSC “Institute of Metallurgy and Ore Beneficiation” makes it possible to isolate iron and non-ferrous metals into separate, middling products and to concentrate noble metals in the cake at the first stage. Physical and chemical studies of the cake found that its basis comprises iron compounds. The silver in the cake is associated with pyrite, while the gold is associated with hematite; it is also possible to find gold in the form of AuCl3. The content of gold in the cake is 1.5 g/t, and the silver content is 17.7 g/t. Based on physical and chemical studies and data from the literature, various versions of the hydrochlorination method are proposed to open the cake.

The cyanidation of precious metals from ores and secondary resources has been classified as a hazardous process due to the release of toxic gases. The use of environmentally friendly and cost-effective processes is a suitable alternative to cyanidation. Thiourea leaching has been shown to be one of the best alternative reagents to cyanide. The present work aims to evaluate the efficiency of the thiourea leaching of gold and silver from pretreated pyrite cinders. The use of pre-chemical activation prior to leaching helped to increase the amount of free gold and silver particles. A preliminary leaching test led to the selection of Fe2(SO4)3 as a suitable oxidizing agent for Au and Ag leaching. To select suitable leaching parameters, the response surface methodology (RSM) was used to optimize some parameters that can considerably affect sulfuric acid–thiourea leaching and identify the greatest interaction between them. The optimized parameters of 30 g/L thiourea, 10% pulp density, pH = 1, and 50 °C over 4 h of leaching time allowed for Au and Ag recoveries of 98.31 and 88.57%, respectively.

Currently, the production of one ton of ordinary Portland cement (OPC) releases considerable amounts of CO2 into the atmosphere. As the need and demand for this material grows exponentially, it has become a challenge to increase its production at a time when climate-related problems represent a major global concern. The two main CO2 contributors in this process are fossil fuel combustion to heat the rotary kiln and the chemical reaction associated with the calcination process, in the production of the clinker, the main component of OPC. The current paper presents a critical review of the existent alternative clinker technologies (ACTs) that are under an investigation trial phase or under restricted use for niche applications and that lead to reduced emissions of CO2. Also, the possibility of transition of clinker production from traditional rotary kilns based on fuel combustion processes to electrification is discussed, since this may lead to the partial or even complete elimination of the CO2 combustion-related emissions, arising from the heating of the clinker kiln.

Industrial activities have historically generated significant quantities of by-products, including pyrite cinders, a residue produced during the synthesis of sulphuric acid. This study presents a multidisciplinary approach to characterise an abandoned pyrite cinder deposit. Combining geophysical (electrical resistivity tomography—ERT), geochemical, and statistical methods, we assess the physicochemical properties of the deposit and its environmental implications. Our findings reveal the presence of heavy metals, with lead (7017.5 mg.kg−1) being the most concentrated element on the surface of the deposit, exceeding local legal thresholds by more than 163 times, posing environmental risks and inhibiting vegetation growth. Subsurface characterisation indicates a decreasing concentration trend of metals with depth, alongside variations in pH and electrical conductivity. Clustering analysis identifies groups of similar behaviours between resistivity, the most abundant heavy metals, and other variables, providing valuable insights into the complex interplay within the deposit. Our study underscores the importance of integrated approaches in assessing and managing hazardous waste sites, with implications for environmental remediation strategies.

This article deals with the intensification of the grinding process in ball mills. Attention is drawn to the need to reduce the energy input for grinding. Data on cement clinker grinding kinetics when surface-active agents are used, as well as issues of intensification of the grinding process by changing the surface profile of the armor plates are given.

The Malko-Petropavlovsk zone of transverse dislocations (MPZ) was formed on the extension of the deep Avachinsky transform fault in perpendicular relation to the subduction trench. It is a natural boundary between variously aged slabs in Kamchatka (103–105 Ma under Southern Kamchatka and 87–92 Ma under the Eastern volcanic belt). Monogenetic cinder cones in the MPZ are randomly distributed along these long-lived rupture zones. Here we present new geochemical and isotopic results of monogenetic volcanism in the MPZ. Based on whole rock and trace element geochemistry, Pb-Sr-Nd isotopic ratios of monogenetic cinder cone magmas were shown to tap the enriched mantle source (low 143Nd/144Nd isotopic ratios (0.512959–0.512999), and changed as 87Sr/86Sr (0.703356–0.703451) and 206Pb/204Pb (18.30–18.45), 208Pb/207Pb (38.00–38.12) isotopic ratios). High Nb/Yb and La/Yb ratios, without significant inputs of the slab’s components (the lowest Ba, Th content), indicate decompression melting predominately. Calculations of the pressure (9–11 kbar) and temperature (1160–1240 °C) conditions using a glass thermobarometer suggest that magma of monogenetic cinder cones resided near the Moho boundary prior to eruption. This correlates with the crustal discontinuity under the MPZ according to geophysical observations (converted-wave seismic exploration and magnetotelluric sounding). The majority of well-preserved monogenetic cinder cones were formed in Holocene, after the last glaciation, but eruptions were not observed historically. This, however, suggests that similar eruptions in the MPZ may occur in the future. Given that the MPZ hosts major population centres of Kamchatka (Petropavlovsk, Elizovo, Vilyuchinks, and Paratunka: ~ 250,000 people or ~ 80% of the whole Kamchatkan population live in the major cities on the coastline of the MPZ), we highlight the urgent need to install a continuous monitoring system around the MPZ cones, geophysical investigation, and more serious attention from the local government and scientists. In particular, a detailed study of the MPZ regarding age, volume, and volcanic hazard assessment (pyroclastic vs extrusive) will help reduce potential risks of eruptions from monogenetic volcanoes for humans and infrastructures.

The high-hydrolysis reactivity cement clinker powder in cement plays a major role in cement’s cementation, while low-hydrolysis reactivity mineral admixture powders, such as slag, m mainly serve as a filler. Through optimizing the particle matching of cement clinker powder and slag powder, the mechanical properties of cement can be enhanced. In this study, clinker and slag with differing levels of fineness were obtained by separate grinding, and the particle gradation of clinker powder and slag powder in the cement was optimized. Fine clinker particles were mixed with coarse slag particles to systematically explore their effects on the rheology of cement paste, the formation of hydration products, the evolution of the pore structure, and the material’s mechanical properties. Through experimental tests and microscopic analysis, the mechanism whereby particle gradation is regulated by separate grinding was revealed. The findings of the study are as follows: with the same amount of cinder, finer clinker requires a higher water content of standard consistency. The addition of coarse cinder effectively reduces the standard-consistency water requirement of the blended cement. Fine grinding of coal cinder fails to enhance cement strength effectively but markedly raises the standard-consistency water demand. Thus, the specific surface area of coal cinder should be maintained at approximately 210 m2/kg.