Search Results for pyrometallurgical process

Ores, which consist of the primary valuable mineral, predominant gangue content, valuable by-products, and detrimental impurities, are extracted and directed to mineral processing. This article describes the mineral processing facilities, such as crushers, grinders, concentrators, separators, and flotation devices that are used for particle size reduction, separation of particles according to their settling rates in fluids and dewatering of concentrate particles. It explains the basic principles, flow diagrams, ore concentrate preparation methods, and equipment of major types of metallurgical processes, including pyrometallurgical, hydrometallurgical, and electrometallurgical processes.

This article addresses the general welding characteristics common to both solid-solution-strengthened and precipitation-hardened nickel-, iron-, and cobalt alloys.

This article provides a discussion on the corrosion of industrial refractory materials and technical ceramics. These materials, which are used to minimize heat losses and provide a barrier between the vessel and its contents, are utilized in the metallurgical, chemical process, power generation, automotive, and aerospace industries. The article covers the fundamental principles of chemical corrosion of refractories and ceramics, and the use of thermodynamic calculations and kinetic models to evaluate the probability of the occurrence of corrosion-causing chemical reactions. It describes the corrosion resistance characteristics of specific classes of refractories and structural ceramics. The article also examines the prevention strategies that minimize corrosion failures of both classes of materials.

This article focuses on the recycling of metals including iron and steel, stainless steel, superalloys, nickel, aluminum, copper, precious metals, lead, magnesium, tin, titanium, and zinc. It provides information on the identification and sorting of scrap metals and discusses the equipment and procedures used for small-scale and large-scale scrapping operations.

Electrochemical refining is the purification process for producing commercially pure metals from crude metals. This article describes the principles of electrochemical reactions. It discusses the physical properties of the basic components of electrochemical refining cell. The article also explains the engineering considerations required in the refining process. Theoretical and technological principles of electrochemical refining are illustrated, with examples.

Many nonferrous metals, including aluminum, nickel, copper, and others, are among the few materials that do not degrade or lose their chemical or physical properties in the recycling process. As a result, these metals can be recycled an infinite number of times. This article focuses on the recycling of nonferrous alloys, namely, aluminum, copper, magnesium, tin, lead, zinc, and titanium, providing details on the sources, consumption and classification of scrap, and the technological trends and developments in recycling.

Fluxes are added to the welding environment to improve arc stability, to provide a slag, to add alloying elements, and to refine the weld pool. This article describes the effect of oxygen that directly reacts with alloying elements to alter their effective role by reducing hardenability, promoting porosity, and producing inclusions. It proposes basicity index for welding as a measure of expected weld metal cleanliness and mechanical properties. The article discusses alloy modification in terms of slipping and binding agents, slag formation, and slag detachability. It reviews the types of fluxes for different arc welding processes, such as shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), and submerged arc welding (SAW).

Fluxes are added to the welding environment to improve arc stability, provide a slag, add alloying elements, and refine the weld pool. This article discusses the effect of oxygen, which is an important chemical reagent to control the weld metal composition, microstructure, and properties. It provides information on the inclusions that form as a result of reactions between metallic alloy elements and nonmetallic tramp elements, or by mechanical entrapment of nonmetallic slag or refractory particles. The article reviews the considerations of flux formulation during shielded metal arc welding and flux cored arc welding (FCAW). It describes the types of fluxes used for submerged arc welding and FCAW as well as five essential groups of flux ingredients and their interactions.

Ceramic and glass manufacturers take environmental regulations into consideration during all stages of the product cycle, from research and development to purchasing, processing, end use, and disposal. Ceramic and glass products are finding application in the construction industry and as raw materials for other processes. This article describes the recycling of in-process scrap and industrial wastes (fly ash, red mud, metallurgical waste, and other waste products), and applications of these recycled products. It focuses on environmental regulations such as Resource Conservation and Recovery Act and Clean Air Act. The Clean Air Act requires all states to meet minimum emissions standards for nitrogen-oxygen compounds, volatile organic compounds, and carbon monoxide.

Nickel and nickel-base alloys are vitally important to modern industry because of their ability to withstand a wide variety of severe operating conditions involving corrosive environments, high temperatures, high stresses, and combinations of these factors. This article discusses the mining and extraction of nickel and describes the uses of nickel. It discusses the categories of nickel-base alloys, including wrought corrosion-resistant alloys, cast corrosion-resistant alloys, heat-resistant alloys (superalloys), and special-purpose alloys. The article covers the corrosion resistance of nickel with the inclusion of varying alloying elements. It provides useful information on the behavior of nickel and nickel alloys in specific environments describes its corrosion resistance in certain acids, alkalis, and salts.

This article provides an overview of the corrosion theory relating to refractories on the basis of acid/base reactions, thermodynamics, and kinetic considerations. The tests to evaluate refractory corrosive wear are reviewed. The article describes the specific refractories used in steel, glass, aluminum, and chemical-resistant applications. Specific material issues that should be considered or evaluated when choosing or using refractory materials are discussed.

Nickel in elemental form or alloyed with other metals and materials has made significant contributions to our present-day society and promises to continue to supply materials for a demanding future. This article provides a historical overview and physical metallurgy of nickel and nickel alloys. It lists and describes the compositions, mechanical and physical properties, and applications of commercial nickel and its alloys. The article briefly explains the forms of corrosion resulting from the exposure of nickel alloys to aqueous environments. It provides valuable information on the commercial forms of nickel alloys, namely, nickel-copper alloys, nickel-chromium and nickel-chromium-iron series, iron-nickel-chromium alloys, controlled-expansion alloys, nickel-iron low-expansion alloys, soft magnetic alloys, and welding alloys.

Zinc is one of the most used metals, ranking fourth in worldwide production and consumption behind iron, aluminum, and copper. This article commences with an overview of the applications of zinc that can be divided into six categories: coatings, casting alloys, alloying element in brass and other alloys, wrought zinc alloys, zinc oxide, and zinc chemicals. It discusses the corrosion and electrochemical behavior of zinc and its alloys in various environments, particularly in atmospheres in which they are most widely used. The article tabulates the corrosion rates of zinc and zinc coatings immersed in various types of waters, in different solutions in the neutral pH range, and in soils at different geographic locations in the United States. It concludes with information on the forms of corrosion encountered in zinc coatings, including galvanic corrosion, pitting corrosion, and intergranular corrosion.

Copper and copper alloys are widely used because of their excellent electrical and thermal conductivities, outstanding resistance to corrosion, and ease of fabrication, together with good strength and fatigue resistance. This article provides an overview of property and fabrication characteristics, markets, and applications of copper and its alloys. It contains several tables that provide helpful information on the chemical composition, classification, designation, uses, and mechanical properties of wrought copper and copper alloys.

Copper and copper alloys constitute one of the major groups of commercial metals due to their excellent electrical and thermal conductivities, corrosion and fatigue resistance, ease of fabrication, and good strength. This article lists the types, properties, fabrication characteristics, corrosion ratings, temper designations, and applications of wrought copper and copper alloys. It also presents an outline of the most commonly used mechanical working and heat treating processes. The copper industry in the United States is broadly composed of two segments: producers (mining, smelting, and refining companies) and fabricators (wire mills, brass mills, foundries, and powder plants). The article discusses copper production methods and describes major changes in the structure of the U.S. copper and copper alloys industry.