TECHNOLOGIES FOR IMPROVING ENERGY EFFICIENCY IN THE MINING AND METALLURGICAL INDUSTRIES USING HYDROGEN

ABSTRACT

The article discusses the possibilities of using hydrogen technologies to improve energy efficiency and environmental sustainability of metal mining and processing in the USА. The study identifies the current state of both metallurgical and mining industries and finds main issues in terms of excessive energy consumption and immense carbon footprint. The potential for hydrogen as a reducing agent and energy source in the steel technology cycles, alloy production and ore processing are discussed. Special attention is drawn to its thermodynamic advantages, and its ability to reduce greenhouse gas emissions by replacing carbon reagents. Its technological and infrastructural constraints are considered, along with the possibility of its widespread usage with the support of the state.

АННОТАЦИЯ

В статье рассматриваются возможности применения водородных технологий в целях повышения энергоэффективности и экологической устойчивости процессов добычи и переработки металлов в США. Исследуется современное состояние горнодобывающей и металлургической отраслей, выделяются основные проблемы, связанные с высоким уровнем энергопотребления и значительным углеродным следом. Анализируется потенциал водорода как восстановителя и источника энергии в технологических циклах производства стали, сплавов и при обогащении руд. Особое внимание уделяется его термодинамическим преимуществам, а также способности снижать выбросы парниковых газов при замещении углеродных реагентов. Рассматриваются технологические и инфраструктурные ограничения, а также перспективы его масштабного внедрения при поддержке государства.

Keywords: hydrogen technologies, metallurgy, mining industry, energy efficiency, decarbonization, USA.

Ключевые слова: водородные технологии, металлургия, горнодобывающая промышленность, энергоэффективность, декарбонизация, США.

Introduction

The USA is one of the world leaders in metallurgy, being not only a major producer, but also a consumer of ferrous and non-ferrous metals. While this production is among the most carbon-intensive industries. Against the background of stricter national and international environmental requirements, the transition to a low-carbon economy, and the rising demand for environmentally friendly goods, the challenge of thorough modernization of the metallurgical complex using resource-conserving and climate-neutral technologies has grown more urgent.

One of the most promising areas is the introduction of hydrogen technologies with the potential to drastically reduce direct carbon dioxide emissions. Due to the high reducing activity and ecological purity of combustion products, it is considered as an effective alternative to traditional carbon-containing energy carriers and reducing agents. The purpose of the article is to analyze the technological possibilities of increasing the energy efficiency of metal mining and processing using hydrogen.

Research methodology. Current state and issues of the industry

The metallurgical and mining sector of the USA is a high-technology and capital-intensive industry of strategic significance for ensuring national economic stability and industrial security. However, despite the achieved level of technological development, the processing, enrichment, and production of raw metal materials are all still energy-intensive processes of enormous environmental burden.

The most prominent exploitation of mineral resources is through open-pit and sub-surface exploitation, which comes with immense utilization of heavy machinery, drilling, and blasting methods, and transportation networks. All these processes require enormous amounts of electricity and fuel, thereby diminishing the efficiency of natural resource extraction. At the level of raw material processing, technology processes such as crushing, grinding, flotation, magnetic, and gravity separation are utilized. Each of these requires massive energy costs, especially if fine grinding must be done to refine hard-to-enrich minerals.

The processing of metal raw materials, particularly in ferrous metallurgy, is accomplished using blast furnaces and oxygen converter plants, the main energy sources of which are carbon materials. Despite optimization efforts spanning decades, these processes remain sources of huge carbon dioxide emissions [1].

Apart from direct atmospheric emissions, there are also nitrogen oxides, sulfur dioxide, methane, and particulate matter emitted during the combustion process and during enrichment. These substances have a complex effect on ecological systems, contributing to acid rain, soil and water pollution, as well as an increased risk of respiratory diseases among the population of industrial regions. In addition, traditional technologies have high water and land impacts. Large quantities of water are utilized in washing ore, cooling equipment, and dust suppression, leading to a risk of water resource depletion and secondary pollution by wastewater [2].

Thus, the current state of the USA metallurgy and mining industries is that of large energy and resource burdens, ongoing releases of greenhouse gases and poisonous chemicals, and mass-scale anthropogenic impacts on environmental elements. These conditions call for systemic adjustment of technological processes to increased energy efficiency, reduction of emissions, and transition to more eco-friendly technologies, and among them the application of hydrogen is of particular significance.

Hydrogen in metallurgy

Hydrogen technologies are a complex of scientific and technical solutions related to the production, storage, transportation, and use as an energy carrier or chemical reagent. With the transition of the world to a new energy and the growing climate issues, it is increasingly considered a pillar driver of a low-carbon economy that can be utilized to replace traditional resources in energy, transport, industry, and, including metallurgy.

Hydrogen has a number of advantages that define its high technological value. Thermodynamically, it has a high heat of combustion - about 120 MJ/kg, and that is more than twice the corresponding value for natural gas [3]. In addition, the product of its combustion is water vapor, and that eliminates the emission of pollutants normally associated with combustion of hydrocarbon fuels. In addition, it is capable of participating in various chemical and technological reactions, including reduction, synthesis, and plasma, with its effect on metals changing in relation to some production process parameters. It is particularly important in metallurgy because it can replace coke and natural gas in high-temperature processes, thus eliminating the primary source of carbon emissions [4].

Today, this approach is increasingly becoming part of the global energy transition. According to International Energy Agency estimates, global low-emission hydrogen production can reach as much as 49 million tons annually in 2030, or approximately 30% more than in 2023. Furthermore, the number of projects for which the final investment decision has been made has increased strongly, showing an actual willingness for industrial deployment [5].

Hydrogen application opportunities in the mining industry

The employment of hydrogen in technological processes of the mining industry is an intriguing approach for boosting energy efficiency, carbon load reduction, and innovating the industry based on sustainable development concepts. It is not only considered an energy carrier but also an active chemical agent that can substantially modify approaches to extracting and processing raw materials of minerals. Table 1 presents the main directions for its use within the mining industry.

Table 1.

Areas of hydrogen application in the mining industry [6, 7]

Thus, the introduction of such technologies demonstrates high potential both in the field of ore processing and at the stage of their direct extraction. Implementation of such strategies requires big investments in infrastructures and science and technical services. However, with the support of the USА government and international climate programs, they can become the foundation on which the sustainable development of the mining industry will be based in the coming decades.

Opportunities for hydrogen application in the metallurgical industry

The metallurgical use of hydrogen is a strategically important trajectory for heavy-industry decarbonization. Modern trends aimed at achieving carbon neutrality stimulate the search for alternatives to traditional carbon-containing reagents, among which it occupies a special place due to its thermodynamic and environmental advantages.

One of the areas of its application is the reduction of metals from their oxide forms. In a technological context, the use of the hydrogenation process is becoming relevant. This is a high-temperature reaction between hydrogen and metal oxides (fig. 1).

Figure 1. Mechanisms of metal oxide reduction by hydrogen [8]

This process makes it possible to obtain pure metal without the formation of carbon by-products, since the reaction results in water vapor. The temperature, pressure, and surface area of the reaction regulate the kinetics, which allows certain operating conditions of industrial production to be optimized to a certain extent.

The main advantages are low carbon emissions, the ability to work in closed cycles with recycling of generated steam, and potential cost reduction on emissions disposal. However, large-scale application of this technology has a number of disadvantages. The major challenges are linked with the vulnerability of the process to raw material contamination, and the very high cost of hydrogen [9]. In addition, the equipment for the use of carbon-based reductants will have to be modernized or replaced in whole, which equates to capital outlay.

Another direction is to use hydrogen to melt metal. Here, it acts as a source of fuel, replacing natural gas, coal, or oil in furnaces of various designs. These operations are based on its combustion under an oxygen atmosphere, which allows one to attain temperatures comparable to those of traditional heat sources without emissions. This is a particular case for the non-ferrous metals, where purity developed during smelting and the chemical composition of the gaseous air are critical factors in controlling the final metal properties. Adding hydrogen to arc, induction and flame furnaces could improve thermal efficiency and reduce the cost of gas purification and filtration systems.. But even though the environmental and technological benefits are very apparent, this technique has its problems with managing heat flow, controlling the gas phase composition, and ensuring safe operation.

The use of hydrogen in alloy and metal product fabrication opens new prospects for the adoption of proven processes into environmental needs. Because it is possible to regulate the reducing environment and process thermal profile, it makes high-purity alloy production feasible, particularly in high-technology sectors. It allows for the removal of impurities and unwanted phases in the alloy structure, which improves the products' mechanical and corrosion properties.

In the future, the widespread introduction of such technologies in metallurgy may become the basis for creating a fully decarbonized chain from mining to the production of finished products. Achieving this level requires not only technical innovation, but also the formation of an appropriate infrastructure. Investments in research and development, government support, and standardization of processes play a crucial role here.

Results

Energy efficiency and environmental benefits of hydrogen technologies

The transition to hydrogen technologies provides an opportunity to increase energy efficiency by replacing traditional carbon-containing energy sources. In metallurgy, its use makes it possible to reduce heat losses due to a high specific heat of combustion and cleaner burning. Thus, in the processes of direct reduction of iron, the transition from natural gas to hydrogen leads to a reduction in total energy consumption by up to 10-15%, especially when optimizing the technological scheme using secondary heat.

In parallel, hydrogen technologies enable a significant reduction in greenhouse gas emissions. When hydrogen are used as a reductant in metallurgy, the formation of carbon dioxide is completely eliminated in reduction reactions, being replaced by water vapor. The impact of these technologies on environmental quality also manifests in changes to the composition of secondary pollutants. The removal of fossil fuels from combustion and reduction processes eliminates particulate sources of emissions, sulfur-containing compounds, and other toxic fractions, producing less sediment acidity, soil and water contamination. Additionally, risks to the health of workers and the population living nearby industrial plants are reduced. Hydrogen use in closed or semi-closed technological systems also allows introducing a circular production mode, where resources are recycled with minimal losses and emissions.

In the USA, real steps are being taken to introduce hydrogen into metallurgical production. In March 2024, it was officially announced that federal funding would be allocated for two large-scale projects aimed at producing «green» steel. One of these projects is being implemented by Cleveland-Cliffs, the largest steel producer with a full metallurgical cycle in the USA, while the other is being carried out by SSAB’s North American division. The latter project is particularly significant because it will be based on the hydrogen-based direct iron reduction technology developed under the Hydrogen Breakthrough Ironmaking Technology program [10].

The application of hydrogen technology in the USA not only demonstrates the technological integration of international experience but also highlights the growing institutional support from the government. These projects show that hydrogen metallurgy is moving from the demonstration stage to industrial scaling, and confirm that it is considered as a strategic resource for the deep decarbonization of heavy industry.

Conclusion

The use of hydrogen technologies in the mining and processing of metals opens new horizons for improving energy efficiency and reducing the environmental impact. Amid the transformation of the USA industry towards a low-carbon model, hydrogen is not only an alternative energy resource but also a strategic factor in the modernization of the metallurgical and mining complexes. Its application provides for a stark reduction in the greenhouse gas emission rate, omission of carbonaceous reducing agents, and introduction of cleaner and technology-adjustable options into production flows.

However, extensive application of such technologies requires an integrated strategy, such as the creation of infrastructure, reducing the price of green hydrogen, standardization of technological processes, and state assistance. In the long term, such a transition in the metallurgy and mining industries can become the basis for the formation of fully decarbonized value chains that meet modern sustainable development needs.

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