Producing Materials

For nearest producer, material in tank cars or trailers unless otherwise noted. Material in 0.208-m dmms. 

Size reduction (qv) or comminution is the first and very important step in the processing of most minerals (2,6,10,20—24). It also involves large expenditures for heavy equipment, energy, operation, and maintenance. Size reduction is necessary because the value minerals are intimately associated with gangue and need to be Hberated, and/or because most minerals processing/separation methods require the ore mass to be of certain size and/or shape. Size reduction is also required in the case of quarry products to produce material of controlled particle size (see Size measurement of particles). In some instances, hberation of valuables or impurities from the ore matrix is achieved without any apparent size reduction. Scmbbers and attritors used in the industrial minerals plants, eg, phosphate, mtile, glass sands, or clay, ate examples. 

Surface Modification. Plasma surface modification can include surface cleaning, surface activation, heat treatments, and plasma polymerization. Surface cleaning and surface activation are usually performed for enhanced joining of materials (see Metal SURFACE TREATMENTS). Plasma heat treatments are not, however, limited to high temperature equiUbrium plasmas on metals. Heat treatments of organic materials are also possible. Plasma polymerization crosses the boundaries between surface modification and materials production by producing materials often not available by any other method. In many cases these new materials can be appHed directly to a substrate, thus modifying the substrate in a novel way. 

Substituted Amide Waxes. The product of fatty acid amidation has unique waxlike properties (13). Probably the most widely produced material is N,1S7-distearylethylenediarnine [110-30-5] which has a melting point of ca 140°C, an acid number of ca 7, and a low melt viscosity. Because of its unusuaHy high melting point and unique functionaHty, it is used in additive quantities to raise the apparent melting point of themoplastic resins and asphalts, as an internal—external lubricant in the compounding of a variety of thermoplastic resins, and as a processing aid for elastomers. 

Feeding devices, stirring, and baffles all produce material flow that contributes to convection. Material flow between surfaces moving at different velocities... 

Copper Hydroxide. Copper(II) hydroxide [20427-59-2] Cu(OH)2, produced by reaction of a copper salt solution and sodium hydroxide, is a blue, gelatinous, voluminous precipitate of limited stabiUty. The thermodynamically unstable copper hydroxide can be kiaetically stabilized by a suitable production method. Usually ammonia or phosphates ate iacorporated iato the hydroxide to produce a color-stable product. The ammonia processed copper hydroxide (16—19) is almost stoichiometric and copper content as high as 64% is not uncommon. The phosphate produced material (20,21) is lower ia copper (57—59%) and has a finer particle size and higher surface area than the ammonia processed hydroxide. Other methods of production generally rely on the formation of an iasoluble copper precursor prior to the formation of the hydroxide (22—26). 

When the cascade is operated usiag the optimum x the cost of producing material at any other concentration, j/p, is given by ... 

Electrolyte is added to the recipe to help control particle size of the latex produced. Materials like sodium carbonate or trisodium phosphate are commonly used. 

Electrochemical systems are found in a number of industrial processes. In addition to the subsequent discussions of electrosynthesis, electrochemical techniques are used to measure transport and kinetic properties of systems (see Electroanalyticaltechniques) to provide energy (see Batteries Euel cells) and to produce materials (see Electroplating). Electrochemistry can also play a destmctive role (see Corrosion and corrosion control). The fundamentals necessary to analyze most electrochemical systems have been presented. More details of the fundamentals of electrochemistry are contained in the general references. 

The feed must be nonabrasive with a hardness of 1.5 or less. The miU is capable of taking 2-cm ( A-in) feed material, depending on the size of the feed throat, and reducing it to a product substantiaUy aU able to pass a No. 200 sieve. For producing materials in the fine-size range, it may be operated in conjunction with external air classifiers. Such an arrangement is shown in Figs. 20-12 or 20-42. A number of machines have internal air classifiers. 

These and other considerations have led to attempts to produce materials which effectively cross-link on cooling to room temperature after processing but which on reheating appear to lose their cross-links. Several approaches to such fugitive cross-linking have been made in recent years of which the following have come to, or at least near to, commercial fruition ... 

Identify all hazardous process materials, intermediates and wastes Produce material information sheets for each process material... 

Benson and Ponton (1993) and Ponton (1996) have speculated on the ultimate results of continuing efforts for process minimization. They envision a twenty-first century chemical industry totally revolutionized by technological innovation, automation, and miniaturization. Small, distributed manufacturing facilities would produce materials on demand, at the location where they are needed. Raw materials would be nonhazardous, and the manufacturing processes would be waste free and inherently safe. While their vision of future technology is speculative, we are beginning to see progress in this direction. 

Epoxy, polyester, phenolic and other resins are used as coatings and linings with or without reinforcement. Glass fiber, silica, carbon and many other materials can be used as filters or reinforcement to produce materials with specific properties of strength, flexibility, wear resistance and electrical conductivity. 

The addition of about 20% nickel to cast iron produces materials with a stable austenitic structure these materials are sometimes known as austenitic cast irons but are more often referred to commercially as Ni-Resist cast irons. The austenitic matrix of these irons gives rise to very different mechanical and physical properties to those obtained with the nickel-free grey cast irons. The austenitic matrix is more noble than the matrix of unalloyed grey irons and it was shown in the early work of Vanick and Merica that the corrosion resistance of cast iron increases with increasing nickel content up to about 20% (Fig. 3.42). 

Quality control tests are intended to detect produced materials which deviate from manufacturing specifications, and thus may result in questionable performance. The materials are usually subjected to spectrographic analysis which is the primary quality control check. The exposure tests are necessarily of short duration (hours or days), in which the test conditions attempt to reflect the environment of operation, for example using artificial seawater for a marine application. Since a property that is reproducible and indicative of a consistent quality anode is all that is required, there is no attempt to mirror, except in the crudest fashion, current density profiles. 

Nitrated Hydroformed Naphthas. The nitration of hydroformed naphthas with mixed nitric-sulfuric acid contg a small amt of w (Ref 2) produced materials which may be used either in expls or as intermediates in the dye industry. 

To produce material dense enough for pyrot usage (2.0—2.1g/cc), the commercial reaction medium is maintd at 50—75°. The final prod is moistened with hot coned Sr(N03)2 soln and dried at 120—50° (Ref 4). 

The smoke producing material and the pyrotechnic fuel block required to volatilize the smoke material are in separate compartments. The smoke-producing material is atomized and vaporized in the venturi nozzle by the hot gases formed by the burning of the fuel block... 

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