Aluminum electrometallurgy

Paul-Louis-Toussaint Heroult. 1863-1914. French metallurgist. Independent discoverer of the electrolytic method of preparing aluminum now known as the Hall-Heroult process. He designed electric furnaces, and made many important contributions to the electrometallurgy of iron and steel... 

In steelmaking applications, calcium disilicide has hitherto been generally more widely used than calcium metal. Total consumption of calcium disilicide in the steel industry worldwide is estimated to be about 6000 tons (30% Ca). Principal producers are Pechiney Electrometallurgie of France and SKW Trostberg of Germany. In the United States, the Norwegian company Elkem Metal produces up to 2500 metric tons of calcium disilicide. Also produced are CalSiBar, a calcium—silicon—barium alloy, and Hypercal, a calcium—silicon—barium—aluminum ferroalloy. 

The metals considered by the NCST are aluminum, copper, lead, zinc, and magnesium. With a view toward the demand for these metals and their alloys, the plans proposed by the NCST panel include (I) facilities for hydrometallurgy and electrometallurgy, (2) production of magnesium, and (3) production of high-strength aluminum and magnesium alloys for the defense and space industries. 

Carbon electrodes are crucial for a number ofimportant processes in molten salt electrometallurgy. A long list of commonly used metals, such as aluminum, sodium, potassium, calcium, and magnesium are produced by these processes [77, 78]. 

Electrometallurgy. A major application of electrochemical principles and techniques occurs in the manufecture of such metals as aluminum and titanium. Plentiful aluminum-containing bauxite ores exist in lai e deposits in several countries, but it yms not until electrochemical techniques were developed in the United States and France at the end of the nineteenth century that the cost of manufecturing this light metal was sufficiently reduced to make it a commercially valuable commodity. This commercial process involved the electrolysis of alumina (aluminum oxide) dissolved in fused cryolite (sodium aluminum fluoride). During the century that followed this process s discovery, many different uses for this lightweight metal ensued, from airplanes to zeppehns. 

The electometallurgy industry, like many industries, poses challenges for society. Metals have great value and many uses, which are an essential part of modern life. Unfortunately, electrometallurgy consumes huge amounts of energy and uses tons of unpleasant chemicals. In addition, aluminum plants emit carbon dioxide and fluorine compounds. However, the use of electricity to produce metals probably remains the cleanest and most efficient method. 

Electrometallurgy, which utilizes electrochemistry to reduce and refine metals, is examined with attention to sodium, aluminum, and copper. 

Section 23.4 Electrometallurgy is tire use of electrolytic methods to prepare or purify a metallic element. Sodium is prepared by electrolysis of molten NaCl in a Downs cell. Aluminum is obtained in the Hall process by electrolysis of AI2O3 in molten cryolite (NagAlFg). Copper is purified by electrolysis of aqueous copper sulfate solution using anodes composed of impure copper. 

In electrometallurgy, electrolysis is used to produce metals from their compounds. For example, the Hall process is an electrometallurgical process crucial to aluminum production. The main source of aluminum is bauxite, AI2O3 n H2O. A hydrometallurgi-cal process, the Bayer process, separates bauxite from the irou aud silicon dioxide with which it is usually found. In this process, the bauxite is heated in a concentrated aqueous NaOH solution under high pressure. The aluminum oxide dissolves, leaving the other oxides behind in solid form. 

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