Allen S. Russell

Solubility and Density of Hydrated Aluminas in NaOH Solutions

Solubilities and densities are reported for alumina hydrates in NaOH solutions under the conditions of the Bayer process employed to purify alumina for aluminum production. The equilibrium constants for reactions to form AlO2- accurately correlate the effects of NaOH concentration on the solubilities; the temperature coefficients of the equilibria lead to heats of solution of 7.34, 4.76, and 5.24 kcal for the a trihydrate, α monohydrate, and β trihydrate, respectively. Moderate calcination does not change the solubility of the a trihydrate but increases that of the α monohydrate. At solution temperatures above 100°C, the trihydrates transform rapidly to a monohydrate. Hydro-thermally produced α monohydrate is the stable phase above 20°C.

Advances and Prospects in Alumina Technology

The needs of the alumina industry that have dictated its recent technological activities are reviewed. The categories considered are industry growth, capital needs and costs, bauxite availability, energy, automation, and environment. Recycling has emerged as a dominant positive factor in the aluminum industry, but it reduces the need for additional alumina. Slow growth, increased costs, and environmental pressures point out the necessity for the alumina industry to improve its technology to the highest degree possible in existing facilities.

Aluminum Technology Responds to Change

This paper explores the factors and trends influencing aluminum technology. Vigorous development employing diverse and sophisticated disciplines is demanded to take full advantage of aluminum’s inherent versatility and usefulness. Process control improvements have revolutionized aluminum production technology. Previously unattainable standards of quality and productivity have made aluminum a dominant design material. Oppor tunities and challenges are especially evident in automotive and container markets. Dependable low cost production enables researchers to explore new alloy and composite potentials. The research also extends to ceramic materials, where value added profits may exceed traditional structural al markets.

Energy Savings in Aluminum Production, Use, and Recycling

Aluminum and energy have been intertwined since the initial isolation of the metal from its ore, and industry growth has depended on great quantities of inexpensive, available energy. In response to the modern need, the industry has significantly decreased the energy required for the chemical steps in aluminum production. That aggressive effort is catalogued here. The energy-saving potential of a new smelting process is mentioned. The tremendous energy reduction achieved by recycling and improved design of the aluminum beverage can is detailed, and the potential for similar advantages for other products is presented. Finally, the important role of lightweight aluminum in decreasing the nation’s energy requirement for transportation is discussed.