Froth flotation is based on the differences in the physico-chemicalsurface properties of particles of various minerals. It is very seldomthat the mineral to be separated possesses the desirable surface characteristics.Outside intervention is required to alter the natural surface of themineral particles that make up the flotation pulp. The mineral that is tobe floated by attachment to an air bubble must have a hydrophobic surfaceand the rest of the pulp must be hydrophilic or easily wettable. A mineralsurface can be rendered hydrophobic by the attachment of a layer built upof long chain hydrocarbons or of inert organic substances. [...]

[...]The present study, using constant current density, was undertaken in an attempt to elucidate the reaction mechanism. Of particular interest were the effects of acidity, depolarizer concentration, current density and anion concentration on the anode reactions and on the current efficiency with which these processes occur. [...]

Pure metals are generally composed of grains, typically about 0.01 mm. diameter, all identical crystallographically with one another except for orientation of the crystal lattice. The useful materials of engineering are, however, generally not pure metals but alloys, often simple binary alloys, but also quite commonly multicomponent alloys of great complexity. [...]

Zinc is one of the major non-ferrous metals required by industry. Its largest application is in the galvanizing of iron and steel products. A substantial tonnage is also used in the making of brass and in the form of alloys for pressure die-casting. Zinc can be fabricated by almost all of the processes used in metal forming: it can be rolled, extruded, drawn, spun and bent as well as cast. Wrought zinc and zinc alloys have the special anti-corrosion properties that are necessary for many types of service, e.g., in roofing and in sacrificial cathodic protection. [...]

"The process of extrusion has undergone such vigorous development in the course of the last thirty years that it is now entitled to rank among the foremost of the technical methods by which metals are wrought into shape". This quotation is from the text on extrusion by Pearson and Parkins, first published twenty years ago. [...]

An interface can be defined as a bounding surface across which there is a discontinuity of some kind. Such discontinuities need not be abrupt, but may be in the form of a transition zone, so that interfaces may or may not have a thickness. Because of disturbances and irregularities at the interface, atoms there are in a state of higher energy than are the atoms in the homogeneous bulk. [...]

With the rising importance of iron ore beneficiation, a great deal of research has been conducted over the past few years in order to better understand its flotation characteristics. Although hematite in ore deposits is generally loosely associated with gangue and, therefore, presents a relatively easy liberation problem, its flotation is difficult, since the gangue has flotation properties similar to the hematite. [...]

Matte smelting of copper ores and concentrates in North America is carried on entirely in reverberatory and blast furnaces; but in Scandinavia, where fuels are scarce and hydro-electric power is available in quantity, electric furnaces are used for smelting operations. Each type of smelting furnace has its own peculiar advantages and disadvantages, the furnace used being a matter of economics. [...]

With the increased use of weldments and other alternate methods of fabrication over the past few years, there has been much interest in the foundry industry in improving the quality and over-all reliability of steel castings. In recent years, also, the efficiency of the acid-electric steelmaking process for the intermittent operation peculiar to the industry has been reflected by an increasingly larger proportion of the steel used to make castings produced by this method. [...]

Natural manganese dioxide pyrolusite has been known since the time of Pliny as an agent for decolorizing glass. Pyrolusite is usually found mixed with ferric oxide, since both are deposited by atmospheric oxidation of their bicarbonates. It contains about 63 per cent manganese. Minerals of manganese are listed in Table I. The different ores of manganese may also be classified according to the fields in which they are used. This classification can be seen in Table II.