Atomization processes commercial

In the atomizing process, a stream of molten zinc is broken into tiny droplets by the force of a pressurized fluid impinging on the stream. The fluid can be any convenient material, although air is normally used. The atomized drops cool and soHdify rapidly in a coUection chamber. The powder is screened to specified sizes. Particulate zinc is also produced by other methods such as electrolytic deposition and spinning-cup techniques, but these are not of commercial importance. 

The roller atomization process has been applied to the atomization of many metals and alloys, such as lead, tin, aluminum, copper and steel. The production rate is potentially high, and the energy requirement is much lower than in commercial gas and water... 

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... 

The processing and surface preparation of silver particles is critical to their performance as a filler. The first step in manufacturing silver flakes is to produce silver powder. Powdered silver may be produced by chemical precipitation, electrolytic precipitation, or melt atomization. Most commercially available silver powders are precipitated by reducing silver from a silver nitrate solution. Particle sizes of powdered silver range from submicron to 5 pm." Silver powders are selected based on size and... 

Electrical energy is used almost exclusively for the drying, ashing, and vaporization steps in flameless atomization. In commercially available instrumentation these steps are programmed sequentially, with each step in the process being adjustable. Readout of the analytical signal can be either... 

A different type of chemistry has been realized in the process commercialized by EniChem in 1986, which is based on employment of and the titanium-silicalite TS-1 as heterogeneous catalyst [106, 111]. The hydroxy lation mechanism involves activation of hydrogen peroxide via the formation of a titanium hydroperoxo complex, TiOOH, followed by electrophilic oxygen atom transfer to phenol. Methanol and acetone are the solvents of choice to achieve high selectivity. The nature of solvent, phenol concentration, reaction time, and size of catalyst particles affect the CAT/ HQ ratio. The TS-l-based process offers clear advantages in terms of conversion, selectivity, efficiency (see Table 14.1), catalyst separation/recycling, and, hence, environmental impact. 

The Ziegler process, based on reactions discovered in the 1950s, produces predorninandy linear, primary alcohols having an even number of carbon atoms. The process was commercialized by Continental Oil Company in the United States in 1962, by Condea Petrochemie in West Germany (a joint venture of Continental Oil Company and Deutsche Erdid, A.G.) in 1964, by Ethyl Corporation in the United States in 1965, and by the USSR in 1983. 

Phosphites. Tertiary phosphites are also commonly used and are particularly effective ia most mixed metal stabilizers at a use level of 0.25—1.0 phr. They can take part ia a number of different reactions duting PVC processing they can react with HCl, displace activated chlorine atoms on the polymer, provide antioxidant functionaHty, and coordinate with the metals to alter the Lewis acidity of the chloride salts. Typical examples of phosphites are triphenyl phosphite [101 -02-0], diphenyl decyl phosphite [3287-06-7], tridecyl phosphite [2929-86-4], and polyphosphites made by reaction of PCl with polyols and capping alcohols. The phosphites are often included in commercial stabilizer packages. 

Lead Monoxide. Lead monoxide (litharge), PbO, occurs as a reddish alpha form, which is stable up to 489°C where it transforms to a yellow beta form (massicot). The latter is stable at high temperatures. The solubihty of a-PbO ia water is 0.0504 g/L at 25°C the solubihty of the p-PbO is 0.1065 g/L at 25°C (40). Lead monoxide is amphoteric and dissolves ia both acids and alkahes. In alkahes, it forms the plumbite ion PbO - The monoxide is produced commercially by the reaction of molten lead with air or oxygen ia a furnace. Black or gray oxide is manufactured by the Barton process, by the oxidation of atomized molten lead ia air, as well as by the ball mill process, ia which metallic lead balls of high purity are tumbled ia the mill to form partially oxidized lead particles. 

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

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