Non-ferrous Research Articles

Global scenarios of anthropogenic mercury emissions

Abstract. Anthropogenic mercury (Hg) emissions to the atmosphere are a long-lived hazard to human and environmental health. The UN Minamata Convention on Mercury is seeking to lower anthropogenic mercury emissions through a mix of policies from banning certain Hg uses to reducing unintentional Hg release from different activities. In addition to independent Hg policy, strategies to mitigate greenhouse gases, particulate matter (PM) and SO2 may also lower Hg emissions as a co-benefit. This study uses the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) model to examine the effect of different clean air and climate policies on future global Hg emissions. The baseline scenario assumes current trends for energy use and Hg emissions as well as current legislation for clean air, mercury and climate policy. In addition, we explore the impact of the Minamata Convention, the co-benefits of climate and stringent air pollution policies, and maximum feasible reduction measures for Hg. Hg emission projections until 2050 show noticeable reductions in combustion sectors for all scenarios due to a decrease in global fossil fuel and traditional biomass use, leading to emission reductions of 33 % at baseline and up to 90 % when combining stringent climate controls and the most efficient Hg controls. Cement and non-ferrous metal emissions increase in all scenarios with current air pollution policy but could be reduced by up to 72 % and 46 %, respectively, in 2050 with stringent Hg-specific measures. Other emissions (including waste) are a significant source of uncertainty in this study, and their projections range between a 22 % increase and a 54 % decrease in 2050, depending on both climate and clean air policy. The largest absolute reduction potential for Hg abatement but also the largest uncertainties regarding absolute emissions lie in small-scale and artisanal gold production, where abatement measures could eliminate annual Hg emissions in the range of 601–1371 t (95 % confidence interval), although the uncertainties in the estimate are so high that they might eclipse reduction efforts in all other sectors. In total, 90 % of Hg emissions are covered by provisions of the Minamata Convention. Overall, the findings emphasize the necessity to implement targeted Hg control policies in addition to stringent climate, PM and SO2 policies to achieve significant reductions in Hg emissions.

Production of effective materials on the basis of sulfuric acid industry wastes

Introduction. Solving the urgent problem of the production of special concretes using certain varieties of substandard natural raw materials and a number of industrial wastes will support introducing the principles of resource saving and improving the technological features of production.Aim. To make a comprehensive assessment of the impact of sulfuric acid production wastes and substandard natural clay raw materials on the production of high-quality and durable concretes for special purposes.Materials and methods. Easily fusible clay rocks serve as a raw material for the production of expanded clay gravel. Organic (solar oil) and ferruginous (pyrite cinders) additives were used. X-ray analysis was carried out to determine the crystalline phases in the clay of the Nikolskoe oil-field, in the resulting expanded clay gravel, as well as to analyze the factory bulk samples of pyrite cinders. A tubular electric furnace was used for firing in a two-stage mode of 700 and 1100 °C to obtain high-strength expanded clay gravel under laboratory conditions. The research involved studying parameters of phosphate binder formation and properties of iron phosphate concrete based on H3PO4 and sulfuric acid industry wastes – pyrite cinders.Results. It was found that Nikolskoye field clay forms a good raw material for the production of high-strength heavy expanded clay gravel with a strength of up to 550 kg/cm2, water absorption of 1.5 % and resistance to aggressive environments, thereby making it suitable for manufacturing special concretes. The results obtained specify the test methods and technical requirements, control methods and product acceptance rules, thus improving the quality and durability of the concretes considered.Conclusions. The investigated non-bloating clay can be used with organic and ferruginous additives to obtain high-strength expanded clay gravel for the manufacture of structural concretes. A mixed iron phosphate binder serves for producing heat-resistant concretes for linings of melting and casting units in non-ferrous metallurgy with high resistance and durability.

Analysis and Design of Engraving Machine Movement

CNC routers play a significant role in several markets such as furniture design, circuit board manufacturing, plastic and foam fabrication. It can allow to complete projects in few hours that used to take several days CNC routers can work on sheets of woods, plastic, rubber, acrylics, and non-ferrous metal and CNC router machine moves and cuts in three directions using computer aided design software.A computer program has been established to design the power screws of any engraving machine. The power required to cut material was calculated by the program. The resisting force was analyzed and all stresses act on the power screws. The power screws were designed by using the main common theory of failures. The buckling and maximum deflection was checked in this program.An example of the output results was designed and drawn in Advanced Centre of Technology using solid works software. The nut connected to the screws was also drawn. The parts of engraving machine have been manufactured and tested in Advanced Centre Technology A.C.T in Libya.

The effects of the separator structures and magnetic roller arrangements on eddy current separation

The eddy current separator is the key equipment used for the separation and enrichment of non-ferrous metals from the solid waste. The customization and universality requirements for eddy current separators have been improved with the increasingly strict environmental protection requirements in various industries and the pursuit of higher economic benefits by enterprises. The low separation efficiency of the small-sized non-ferrous metals and the difficulty in separating between non-ferrous metals are two urgent problems that limit the development of the eddy current separation. The separator structures design, the factors regulation and the core component magnetic roller optimization are the keys to solve problems. Vertical and horizontal eddy current separators are the two main types of permanent magnet eddy current separators in practical applications and reported studies. However, the study and production cost of the eddy current separator are high, and there are few reports on the separator structures in existing studies. There is also a lack of comparative analysis of different applicable conditions for eddy current separators and optimization design of the magnetic roller. This study compared and analyzed the effects of different factors on the vertical and horizontal eddy current separation efficiency, and clarified the advantages and prospects of the vertical eddy current separator in optimizing the separation efficiency between non-ferrous metals. The comparison and multi-objective optimization were conducted on the magnetic rollers to expand the particle size range that can be separated. The separation performance and the economy of the magnetic roller have been improved significantly, and the performance indicators are better than those of existing equipment with the same specifications. The magnetic roller with specific structural parameters has increased eddy current force and magnetic efficiency density by 75.0% and 63.5%, respectively. It is expected to further expand the applicable materials for the eddy current separator.

ТРИБОТЕХНИЧЕСКИЕ ИССЛЕДОВАНИЯ ВТОРИЧНЫХ БРОНЗОВЫХ ПОКРЫТИЙ

One of the features of agricultural machines is the use of a sufficiently large number of parts made of non-ferrous metals and alloys in their designs, since they have high antifriction properties, corrosion resistance, withstand significant specific loads and high speed conditions. Most often these are bronze plain bearings of the bushing type. Tribotechnical studies of coated samples based on secondary composite materials on a friction machine is an important direction in the development of technologies for the restoration and hardening of bronze parts and assemblies. Secondary composite materials are obtained from production waste by the electroerosion dispersion, which allows to reduce production costs and reduce the environmental burden. Such powders can be used to create repair coatings with high wear resistance. (Research purpose) The research purpose is performing a comparative analysis of the tribotechnical properties of coatings obtained usng secondary composite materials and electric spark processing. (Materials and methods) Samples with bronze coatings were produced for research. Conducted tests on the friction machine II5018. (Results and discussion) It was determined that coated samples based on secondary composite materials have higher wear resistance and less friction compared to uncoated samples. It was found that with increasing load and sliding speed, the difference in wear resistance and friction between coated and uncoated samples increases. The coating based on secondary composite materials is especially effective in conditions of high loads and sliding speeds. (Conclusions) Comparative tribotechnical studies of coated samples based on secondary composite materials have shown that such coatings can be an effective way to increase wear resistance and reduce friction in various machine components.

A STATE OF ART AND PROSPECTS OF RED MUD MANAGEMENT

The basic data on the global volumes and composition of red mud, which is a highly alkaline waste of the aluminum industry, namely the Bayer process – technology for the extraction and purification of alumina (aluminum oxide) from bauxite are presented. The analysis of the current state of red mud management allows to distinguish the following main directions: physical-mechanical, physical-chemical, biological and combined methods of handling it, which are used in agriculture (chemical land reclamation (increasing soil pH), use as fertilizers); building materials industry (cement, construction mortar, expanded clay, fireclay, bricks, building blocks, ceramic tiles, concrete alkali-acid-resistant products, refractories); road construction (soil strengthening for the lower layers of the road surface, asphalt); production of other materials (sorbents, catalysts, flocculants, pigments, caustic soda, filler for polymer composites); ferrous and non-ferrous metallurgy. Currently, the most common methods of red mud utilization are its direct use, use in the construction materials industry, as well as pyrometallurgical technologies, as a result of which iron or its alloys are obtained, as well as slag, from which alumina, titanium, rare earth metals can be extracted or which is processed into various building materials. The most expedient method of red mud disposal is either direct use of red mud with minimal changes in its properties, or complex processing with maximum yield of target components and minimization of new waste generation. At the same time, one of the promising ways of red mud management can be its biological processing with the help of plants and microbes, which will help reduce the dangerous man-made load from red mud in the territory adjacent to bauxite processing plants. Bibl. 113, Fig. 2.

Iron ore development management in the Russian Federation

The Russian mineral resource complex is the basis for economy real sector development. The reserves of oil, gas, ferrous and non-ferrous metals, timber, and other raw materials are the strategic basis for the state economic development stability. The subject of the study is iron ore, by reserves of which Russia is confidently among the top three countries in the world together with Australia and Brazil. The global statistics on iron ore production looks a little different since China and India are ahead of Russia in terms of production volumes after the above-mentioned countries. At a time when the country is facing the task of achieving technological sovereignty, and the metallurgical industry is the driver of developing such industries as machine building, construction, and energy, the mineral and raw materials complex development issues are of undeniable interest and relevance. The technological development strategy of Russia will rely in its implementation on a stable metallurgical industry, where issues and main directions of ferrous metallurgy development have been identified, which are the main purpose of this study.

Ecological problems of technogenic land pollution in the republic of Кazakhstan

A large territory in Kazakhstan is distinguished by the diversity of soils and the complex structure of the soil cover. Soil contamination with heavy metals, especially in the vicinity of large cities and industrial centers, is one of the environmental problems. Of great scientific and practical interest is the determination of the content of heavy metals in soil, their transformation and entry into food and feed. The accumulation of heavy metals in the soil leads to an increase in their concentration in plants, which affects public health. Therefore, the study and identification of areas with high levels of heavy metals in the soil are of increasing importance. The article summarizes the results of a study of soil and vegetation cover in areas adjacent to mining enterprises factories for the production of non-ferrous and rare metals.

Research on Carbon Emissions Estimation in Key Industries Based on the Electricity–Energy–Carbon Model: A Case Study of Henan Province

This study focuses on the carbon emissions of key industries in Henan Province, employing techniques of seasonal adjustment, frequency transformation, and statistical modeling to construct an industry-level “Electricity–Energy–Carbon” model to aid in the high-frequency monitoring of carbon emissions in the province’s industries. Based on relevant data, this research performs high-frequency calculations of carbon emissions from energy consumption in 34 typical industries and from the production processes of 53 typical sub-categories in the industrial sector of Henan. The findings reveal the following: Firstly, industrial energy consumption in Henan accounts for over half of the total provincial energy consumption, with most months seeing proportions around 60%. Industries such as energy, non-ferrous metals, building materials, steel, chemicals, petrochemicals, and paper making contribute to over 80% of the industrial energy consumption’s carbon emissions, often nearing 90% in most months. Secondly, among the major industries, such as non-ferrous metals, chemicals, building materials, and steel, there is a dual challenge of being restricted under the “high energy consumption and high emissions” project while also being required to build key industrial bases, leading to fluctuating trends in historical annual carbon emissions data. Thirdly, six sub-categories, namely plastic products, cement, flat glass, steel, ten types of non-ferrous metals, and alumina, have significant carbon emissions in their production processes, accounting for about 72.3% of the total production-related emissions.

Thermodynamic re-optimization of the CaO–SiO2 system integrated with experimental phase equilibria studies

CaO–SiO2 is the key system in ferrous and non-ferrous metallurgy, ceramic manufacture, cement production, and other applications. A number of discrepancies and gaps in knowledge has been identified and resolved since the last thermodynamic optimization of this system. This study reports new experimental phase equilibria data measured using recent advances in equilibration, sample quenching, and Electron Probe X-ray Microanalysis (EPMA) technique. An updated self-consistent set of thermodynamic model parameters is provided. Most importantly, these updates are integrated with a complete re-assessment of the 20-component Cu–Pb–Zn–Fe–Ca–Si–O–S–Al–Mg–Cr–Na–As–Sn–Sb–Bi–Ag–Au–Ni–Co system directly relevant to applications in the ferrous and non-ferrous metallurgical industries. To obtain a large single set of model parameters, significant advances were made in the computational approach, with a focus on simultaneous parallel optimization of binary and ternary model parameters using an experimental dataset combining binary, ternary, and multicomponent information. The Modified Quasichemical Formalism is used for the liquid slag phase. Thermodynamic properties of solid phases and liquid endmembers are completely revised following the recommendations for the third generation of CALPHAD databases. Other notable changes include the revision of the melting temperature of CaO, justified by extrapolations from the multicomponent systems, as well as a physically realistic heat capacity function for metastable SiO2 below the glass transition temperature. These updated properties expand the areas of application of the database to amorphous and partially crystallized slags at ambient temperatures, such as thermodynamics and kinetics of leaching of toxic elements in an aqueous environment. The fundamental limitations of the existing Modified Quasichemical Formalism are also discussed, along with strategies for addressing them.

Asymmetric effects of commodity and stock market on Chinese green market: Evidence from wavelet-based quantile-on-quantile approach

This study principally concentrates on evaluating the effects of Chinese commodity and stock market on the green market. The Maximum Overlap Discrete Wavelet Transform (MODWT) technique is utilized for decomposing time series into diverse frequency components. Following this, quantile-on-quantile regression (QQ) is implemented to meticulously demonstrates the dependency structure among the variables under diverse market conditions. Results demonstrate that energy has no short-term impact, while non-ferrous metals, palm oil, sugar, and stock impact the green market at high and low quantiles. Booming gold and declining stock negatively affect the green market. In the medium term, the influence of stocks and most commodities diminishes. Bullish coal and lead prices have a positive impact, while bearish zinc, corn, and palm oil prices have a negative impact. Crude oil does not significantly affect the green market. In the long term, both stock and commodities have a positive impact on the green market, particularly at extreme quantiles. When both markets decline, they negatively affect the green market. Finally, Granger causality test reveals a bi-directional linear and non-linear causality between commodity and stock markets and the green market across all time scales, enabling investors to predict green market returns based on commodity and stock returns.

Decarbonization of Production Systems in Foundries

The article discusses the growing importance of decarbonization of production systems in the foundry industry as a response to climate challenges and increasing requirements for sustainable development. The process of reducing greenhouse gas emissions in foundry production is caused by a number of reasons. Decarbonization of the foundry industry refers to actions aimed at reducing greenhouse gas emissions, especially carbon dioxide (CO2). Reducing carbon dioxide emissions is increasingly being considered as a key element of the strategy of both small and large foundries around the world. Foundry is one of the industries that generates significant amounts of carbon dioxide emissions due to the energy consumption in the process of melting and forming metals. There is virtually no manufacturing industry that does not use elements cast from iron, steel or non-ferrous metals, ranging from elements made of aluminum to zinc. The article presents various decarbonization strategies available to foundries, such as: the use of renewable energy, the use of more efficient melting technologies, or the implementation of low-energy technologies throughout the production process. Application examples from different parts of the world illustrate how these strategies are already being put into practice, as well as the potential obstacles and challenges to full decarbonization.

Determining the Reactivity of Selected Biomass Types Considering Their Application in Pyrometallurgical Processes of Metal Production.

In this paper, results of research on the reactivities of selected biomass types considering their application in pyrometallurgical processes of metal production are presented. Walnut shells, sunflower husk pellets and spent coffee grounds were selected as biomass materials. Their use as potential reducers in the process of metallurgical slag decopperisation is an innovative approach to this subject. The thermogravimetric findings show that all three tested biomass types are classified as highly reactive. The time to reach maximum reactivity ranges from 1.5 to 3 min and, the lowest value is recorded for the sample of spent coffee grounds. The sample hold time of two hours enables copper content reduction to approx. 1 wt% for practically all the reducers tested. A longer duration of liquid slag contact with the reducer results in a decreased copper content in the slag to a value below 1 wt%. Copper concentrations of 0.5 wt% and lower are observed with a hold time of 4 h. The preliminary results indicate that there is great potential for the use of this type of material in non-ferrous metallurgy, which may translate into replacing fossil raw materials and thus introducing the principles of a sustainable process in this case of metal production.

Номенклатура металлов и сплавов из сарматских могильников Нижнего Поволжья II в. до н.э. – первой половины II в. н.э. по данным РФА

The work presents the results of an analysis of the chemical composition of 82 objects from non-ferrous and precious metals dating from the 4th century BC – the first half of the 2nd century AD and originating from the excavation of funeral monuments located in the Lower Volga region. Basically, the analysis of the chemical composition of non-ferrous metal was carried out for objects characteristic of the ordinary population of the region: mirrors, jewelry, clothing or household items, and details of horse harnesses; importantly, sampling was random. The data obtained by the XRF method are very interesting and demonstrate a change in the nomenclature of leading alloys. So, for the period of the 2nd century BC – the border of eras, there is a significant number of objects from tin as well as from tin-lead bronze, with a slight presence of products from a multicomponent alloy, an alloy with arsenic. For the period of the 1st – the first half of the 2nd century AD, there is a significant change in the leading types of alloys: zinc-containing alloys such as two- and three-component brass dominate the sample; also significantly increased the share of triple bronze, highly alloyed with lead; there are also products made of copper and tin bronze. Silver products made of silver from different samples are present in all stages. Analysis of alloying components and impurities in the identified alloys made it possible to distinguish in the sample of the 2nd century BC –the border of eras, the influence of the North Caucasian center of non-ferrous metalworking; recorded changes in the nomenclature of alloys of the 1st – the first half of the 2nd century AD arose, most likely, under the influence of the North Black Sea center of non-ferrous metalworking. The presence of high-zinc brass objects in the sample during the period of the 1st – the first half of the 2nd century AD also does not exclude the receipt of this type of brass from the production center located in Central Asia, which is characterized by an extremely high zinc content in the alloy.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СОСТАВА КОМПОЗИТОВ, СОДЕРЖАЩИХ ИМПАКТНЫЕ АЛМАЗЫ, НА ИХ ЭКСПЛУАТАЦИОННЫЕ ХАРАКТЕРИСТИКИ ПРИ ЛЕЗВИЙНОЙ ОБРАБОТКЕ ЦВЕТНЫХ МЕТАЛЛОВ

The paper presents the results of resistance tests of tool composite materials containing nanostructured impact diamonds, in comparison with composites based on synthetic superhard materials, diamond and cubic boron nitride (cBN), and ВК-8 (VK-8) (WC + 8 % Co) hard alloy, during blade processing of workpieces made of brass ЛС-59 (LS -59) (57–60 % Cu) and aluminum alloy AK-7 (Al 92–94 %, Si 6–8 %). Samples of composite materials for wear resistance studies were obtained by thermobaric sintering in a highpressure apparatus. The performance of composites was assessed by the wear of the cutter back surface, as well as by a specially developed method for studying the performance characteristics of composite superhard materials, based on determining their specific productivity. As a result of the tests, it is found that composites based on impact diamonds have the highest resistance when turning non-ferrous metal alloys. In particular, the wear resistance of a composite material containing impact diamonds with the addition of cBN exceeds the wear resistance of cutters made of composite 02 (belbor) by 1.5–3 times, and that of cutters made of hard alloy VK-8 by 8–10 times. Additions of impact diamond to hard alloy in the amount of 6.25 and 12.5 vol.% increase the relative wear resistance of the hard alloy composite compared to the original VK-8 alloy by 10–15 and 20–25 %, respectively.

Вредные вещества в воздухе рабочей зоны горнодобывающего сектора металлурги-ческой промышленности как факторы риска для здоровья работников (аналитический обзор)

Working conditions at non-ferrous metallurgical enterprises typically involve exposure to a whole set of harmful chemicals present in occupational air. These chemicals contribute to the development of pathologies in workers, respiratory diseases in particular. Research literature was analyzed using bibliographic databases in order to summarize available information on effects produced by harmful chemicals in workplace air on health of workers employed at mining enterprises. Respiratory diseases such as pneumoconiosis, acute and chronic dust bronchitis prevail among occupational pathologies typical for underground miners. Acute and chronic bronchitis prevail among respiratory diseases as health disorders resulting in temporary disability of miners dealing with non-ferrous metal mining. Huge amounts of dust appear in occupational air at mining enterprises due to drilling, blasting and ore crushing. Priority chemicals found in workplace air in mining industry include several carcinogens such as nickel, lead, formaldehyde, cadmium, and benzo(a)pyrene. There is a unidirectional effect produced by sulfur dioxide, nickel, nitrogen oxides, acrolein, formaldehyde, cadmium, and particular matter on the respiratory organs. The nervous system can be affected by manganese, lead, and selenium; the blood, by nickel, lead, and carbon oxide; the cardiovascular system, by carbon oxide and selenium. Working conditions of underground miners in non-ferrous metallurgy involve intensive exposure to chemicals in occupational air, which create health risks of occupational respiratory diseases and malignant tumors. Diseases of the nervous, immune, cardiovascular systems and the blood are also possible. When planning a set of preventive activities, it is advisable to identify groups of work-related diseases caused, among other things, by a specific chemical factor.

Harmful chemicals in occupational air in the ore mining sector of the metal industry as occupational health risk factors (Analytical review)

Working conditions at non-ferrous metallurgical enterprises typically involve exposure to a whole set of harmful chemicals present in occupational air. These chemicals contribute to the development of pathologies in workers, respiratory diseases in particular. Research literature was analyzed using bibliographic databases in order to summarize available information on effects produced by harmful chemicals in workplace air on health of workers employed at mining enterprises. Respiratory diseases such as pneumoconiosis, acute and chronic dust bronchitis prevail among occupational pathologies typical for underground miners. Acute and chronic bronchitis prevail among respiratory diseases as health disorders resulting in temporary disability of miners dealing with non-ferrous metal mining. Huge amounts of dust appear in occupational air at mining enterprises due to drilling, blasting and ore crushing. Priority chemicals found in workplace air in mining industry include several carcinogens such as nickel, lead, formaldehyde, cadmium, and benzo(a)pyrene. There is a unidirectional effect produced by sulfur dioxide, nickel, nitrogen oxides, acrolein, formaldehyde, cadmium, and particular matter on the respiratory organs. The nervous system can be affected by manganese, lead, and selenium; the blood, by nickel, lead, and carbon oxide; the cardiovascular system, by carbon oxide and selenium. Working conditions of underground miners in non-ferrous metallurgy involve intensive exposure to chemicals in occupational air, which create health risks of occupational respiratory diseases and malignant tumors. Diseases of the nervous, immune, cardiovascular systems and the blood are also possible. When planning a set of preventive activities, it is advisable to identify groups of work-related diseases caused, among other things, by a specific chemical factor.

Ассортимент изделий из цветного металла раннего железного века поселения Исетское 3 в Нижнем Приисетье

Metal production in the Trans-Ural region in the Early Iron Age is known mainly from materials from the Itkul and Sargat cultures. The article introduces into scientific circulation the largest collection of objects (80 items) made of non-ferrous metal of the Baitovo culture of this period from the settlement of Isetskoye 3, located in the Lower Iset river area. The purpose of the study is to morphometrically characterize and determine the complex typology, as well as to conduct a comparative analysis with synchronous materials. The studied series of items includes weapons (arrowheads), labor tools (knives, a celt, an awl), elements of horse harness (a fragment of a bit), toilet items, jewelry (a mirror, rings, plaques), etc., as well as slags, ingots, and waste bronze foundry production. Preliminary conclusions on production technology were obtained, indicating that stone and clay molds were used for casting. The authors experimentally tested the hypothesis, which was not confirmed, on the possibility of using wooden knife models in the manufacture of clay casting molds. Signs of forging and abrasive casting processing were recorded on several metal objects. Based on their typology and the identified analogies, it was concluded that the complex is characteristic of the Scythian-Siberian cultures and can be dated back to the 7th – 6th/3rd centuries BC, which testifies to the contacts and connections of the Baitovo population with both the western (Itkul) and the eastern metallurgical centers. The presence of slag, a significant amount of bronze casting waste, and mold fragments confirms its local nature, which, however, does not exclude the import of some metal products from other territories.

Effect of in-situ generated MgAl2O4 spinel on thermal shock resistance of magnesia-zirconia refractories

This study aims to advance the application of magnesia-zirconia (MgO–ZrO2) refractories in non-ferrous metal smelting furnaces by enhancing their thermal shock resistance. To fabricate MgO–ZrO2–MgAl2O4 refractories, tabular corundum particles and activated α-Al2O3 powder are integrated into MgO–ZrO2 refractories. The analysis of thermal shock resistance, phase composition, and microstructure of the samples was conducted to gain insights into the toughening mechanisms. The results reveal a substantial enhancement in thermal shock resistance with the addition of 15 wt% tabular corundum (1–0.5 mm) and activated α-Al2O3. Compared to samples without these additives, a notable increase of over 50.0 % in the ratio of residual cold modulus of rupture is shown. The enhancement in thermal shock resistance is primarily attributed to the in-situ generated MgAl2O4 spinel. This process involves volume expansion and increased thermal expansion mismatch, which induce microcrack toughening. Additionally, larger tabular corundum particles form in-situ MgAl2O4 spinel, causing crack deflection and branching, thus extending the crack propagation pathway. Furthermore, the presence of micropores in the spinel zone absorbs the energy required for crack propagation, thereby improving toughness and thermal shock resistance. Consequently, the MgO–ZrO2–MgAl2O4 refractories containing in-situ MgAl2O4 spinel with micropores are promising candidate for chrome-free refractories used in non-ferrous metal smelting furnaces.

Combining chemical analysis and toxicological methods to access the ecological risk of complex contamination in Daye Lake

As one of the nine primary non-ferrous metal smelting bases in China, Daye Lake basin was polluted due to diverse human activities. But so far the pollution status and related ecological risks of this region have not been detailly investigated. In current study, pollutants including heavy metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in eight sediment samples from Daye Lake were quantified. 18S rRNA gene sequencing was employed to profile the nematode community structure within these sediments. Model organism Caenorhabditis elegans (C. elegans) were further applied for a comprehensive ecological risk assessment of Daye Lake. Notably, Cadmium (Cd) was identified as a key driver of ecological risk, reaching an index of 1287.35. At sample point S4, OCPs particularly p,p′-DDT, displayed an extreme ecological risk with a value of 23.19. Cephalobidae and Mononchida showed strong sensitivity to pollutant levels, reinforcing their suitability as robust bioindicators. The composite pollutants in sampled sediments caused oxidative stress in C. elegans, with gene Vit-2 and Mtl-1 as sensitive biomarkers. By employing the multiple analysis methods, our data can offer valuable contributions to environmental monitoring and health risk assessment for composite polluted areas.