Three-stage process

In 1986 Britannia Refined Metals (Northfleet, U.K.) introduced technology for the treatment of Parkes cmst, a triple alloy of Ag, Zn, Pb, which by 1992 had been adopted by seven lead refineries (22). The technology consists of a three-stage process in which the silver-rich cmst is first Hquated to reduce its lead content, then placed in a sealed furnace where the 2inc is removed by vacuum distillation and, finally, the silver—lead metal is treated in a bottom blown oxygen cupel (BBOC) to produce a Htharge slag and dorn metal. 

Heavy water [11105-15-0] 1 2 produced by a combination of electrolysis and catalytic exchange reactions. Some nuclear reactors (qv) require heavy water as a moderator of neutrons. Plants for the production of heavy water were built by the U.S. government during World War II. These plants, located at Trad, British Columbia, Morgantown, West Virginia, and Savaimah River, South Carolina, have been shut down except for a portion of the Savaimah River plant, which produces heavy water by a three-stage process (see Deuterium and tritium) an H2S/H2O exchange process produces 15% D2O a vacuum distillation increases the concentration to 90% D2O an electrolysis system produces 99.75% D2O (58). 

This three-stage process is used for waters of high alkalinity and hardness. It actually removes most of the temporary hardness and so reduces the TDS of the water. However, in the process it increases the proportion of silica in the remainder. Any residual temporary hardness and the permanent hardness are softened in a conventional softener. 

The Reeopet process for the ehemical recycling of PETP is described. The three-stage process, which allows the recovery of highly pure terephthalic acid, commences with continuous saponification followed by chromatographic purification with activated carbon and a final acidification step. 

Stochastic Description of Copolymerization and Network Formation in a Six-Component, Three-Stage Process... 

In this study computational results are presented for a six-component, three-stage process of copolymerization and network formation, based on the stochastic theory of branching processes using probability generating functions and cascade substitutions (11,12). 

A schematic description of the three-stage process of step reactions is given in Figure 1 and further explained below. 

Figure 1. Schematic representation of the three-stage process.

Table I. Typical formulations for a three-stage process of network...

The reduction of molybdenum trioxide to the metal by hydrogen is also a three-stage process which can be represented as... 

Although the present situation and the way ahead appear uncertain, it is clear that enzyme treatment alone does not fulfil the technical requirements for shrink-resist finishing. Even with enzyme treatment, some degree of chlorination (with the attendant AOX problems) and/or application of a resin will still be required. Two-stage or even three-stage processes have been proposed [116] ... 

During and since the Second World War, the three-stage process has been replaced by continuous methods of nitration employing a larger number of stages. In these, the chemical engineering can differ widely, but in principle toluene enters the process at one end and trinitrotoluene is... 

MILOX [Milieu oxidative] A wood-pulping and bleaching process. Wood chips are treated with hydrogen peroxide and formic acid in a three-stage process. Developed by the Finnish Pulp and Paper Research Institute (KCL) and Kemira. Piloted at Oulu, Finland in 1991. 

Construct validation follows a three-stage process. The first stage, theory formulation, involves specifying relationships among constructs and their relation to external variables (e.g., etiological factors). Disorder x is created by process y. For example, a theory about the construct panic disorder could specify that it is caused by the catastrophic misinterpretation of benign bodily cues (Clark, 1986) or by a faulty suffocation monitor (Klein, 1993). Internal... 

These resemble the vat dyes in certain ways, although they are of indeterminate constitution and usually mixtures of different chemical species (section 6.4). The characteristic disulphide group (D-S-S-D in Scheme 1.2) is always present in the insoluble form of a sulphur dye, which is brought into aqueous solution by reduction to the alkali-soluble (leuco) form (D-S ). The soluble sodium thiolate form of the leuco sulphur dye has substantivity for cellulose. Thus the application of sulphur dyes to cellulosic fibres is a three-stage process (Scheme 1.2) broadly similar to that already outlined for vat dyes. 

Most commercial and near-commercial atomization processes for liquid metals/alloys involve two-fluid atomization or centrifugal atomization. As suggested by many experimental observations, two-fluid atomization of liquid metals is typically a three-stage process, 3IX 3 yl whereas centrifugal atomization may occur in three different regimes.[5][320] Many atomization modes and mechanisms for normal liquids may be adopted or directly employed to account... 

Instead, the first step should be a thorough review of processes, machinery variations, employee job functions for all affected job classifications, dust generation points, dust control equipment, and air handling systems (1 ). With this data In hand, and an accurate layout of the plant, one can begin the three-stage process of selecting plant sampling positions. 

The silver ions used in the bacterial snsceptibility tests were released from pure silver electrodes using a 12 V battery-operated direct cnrrent generator. The apparatus used for silver ion generation was described previonsly in [13]. The water-based silver colloidal solution was obtained by a three-stage process based on the... 

Several aromatic diamines were prepared using DDT as starting compound. 4,4 -Diaminobenzophenone was prepared using a three-stage process, including dehydrochlorination of DDT, oxidation of the 1,1-dichloro-2,2-di-(4-chlorophenyl)-ethylene thus formed and amination of 4,4 -dichlorobenzophenone [20, 23] (Scheme 2.8). 

The conventional methanol synthesis is a three-stage process that involves the following steps (1) Catalytic reforming of CH4 by steam—a very endothermic process leading to a synthesis gas consisting of CO, C02 and H2 (2) shift reaction (CO + H20 C02 + H2) to obtain the desired molar ratios H2/CO and H2/C02 and (3) catalytic conversion of synthesis gas to methanol. 

Fluorescence is a three-stage process excitation via the absorption of a radiation, excited state for a very short time -(10 9 sec), and emission. The excitation of a molecule is achieved by the absorption of a light quantum of an appropriate wavelength, promoting, in a simplified view, a ir or nonbonding (n) electron to a 7r antibonding orbital. The quantum yield is a fundamental molecular property that describes the ratio of the number of emitted photons to the number of photons absorbed. 

Methyl benzenesulfinate has been prepared by the three-stage process of reduction of benzenesulfonyl chloride to benzenesulfinic add, conversion of the acid to benzenesulfinyl chloride, and esterification of the chloride with methanol. 7 It has been prepared also by ozonolysis of methyl benzenesulfenate.4 The present procedure is based on one reported by Field, Hoelzel, and Locke.6... 

To summarize, the classical method for analyzing sample rate conversion is to assume that the sample rate conversion factor is or can be approximated by a rational number. Then the sample rate conversion can be viewed as a three stage process, up-sample by an integer factor L, filter by h[n, and down-sample by M. Up-sampling by L inserts L — 1 zero valued samples in between the existing samples of x and decimating by M retains only each M-th sample. This approach is an analytical tool rather than an actual implementation strategy, and it allows the comparison of different sample rate conversion methods in a similar framework. 

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