This paper aims to analyze theoretically events in the economy -ecology -environment (natural resources) mega -system. This analysis includes methodologies making use of the first and second thermodynamic principles (for approaching the waste role in technological processes contour toward environment and the entropy variation importance in the main environmental segments), the application of systems theory and theories relating to emergy. The obtained results allow us to propose, based on the mentioned laws, new techniques and technologies for optimization and increasing efficiency of the economic -ecologicenvironment systems.

As a 21st century trend, sustainability has encompassed the entire world economy, including industry. The concept of “Industry 4.0” is already known today. It promotes the computerization of manufacturing by interconnection, information transparency, technical assistance and decentralized decisions. In recent years, companies in the metal materials industry have also implemented strategies and technologies belonging to the Industry 4.0 concept. The main aim of the manuscript is to identify the key issues in the evolution of the development of the metal materials industry. The transition to a higher level of its evolution is based on two vectors, namely: the ecological paradigm, as a vector of in-depth knowledge, and sustainable material, as a vector that ensures sustainability in the areas of convergence of systems in the spheres of life and social consciousness. The systems that have an impact on the sustainable development of the metallic materials industry through the interactions between them are the technological system, the social system and the natural-ecological system. The main objectives of the paper are the investigations into the interconditions of ecology–economy, and the correlations of ecology–economy–energy, investigations that led to the establishment of new scientific branches (ecometallurgy, metallurgical economics, metallurgical ecosociology and sustainable materials engineering) in terms of global knowledge, and which allow the expansion of the field of implementing knowledge of sustainable development in the metal materials industry. The paper is based on literary foundations, obtained from libraries; databases such as Web of Science (WoS), Scopus and Google Scholar; sustainable universal principles; and legislative parameters.

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Putting in practice the recycling projects of the damaging secondary powder products as dust, scale (mixture of oxides � fabrication defect appearing at rolling) or sand resulted in steel industry effluents removal, needs to be characterized from physical, chemical and technological point of view. This paper aims to realise a new classification of the damaging material and new definitions for their characteristics. The proposed groups are: producing characteristics, impact characteristics, removal characteristics and recycling valorisation characteristics. To underline the technological importance of the used characteristics as work instruments has been programmed experimental researches regarding the diminishing of the recycling of the dust and the sand obtained after the electric arc furnace gas removal and scale from rolling. The characteristics of recycling valorisation have been assessed: chemical composition and Zn assimilation ratio in the steel, the efficiency in liquid steel, the degree of replacing the scrap iron and the recycling chemical composition.