Dissolution wetting process

The formation of the metallic salts is a pyrometaHurgical process, and is commonly referred to as the dry process. The separation of the salts from each other is accompHshed by selective dissolution in water, and is named the wet process. 

Commercial condensed phosphoric acids are mixtures of linear polyphosphoric acids made by the thermal process either direcdy or as a by-product of heat recovery. Wet-process acid may also be concentrated to - 70% P2O5 by evaporation. Liaear phosphoric acids are strongly hygroscopic and undergo viscosity changes and hydrolysis to less complex forms when exposed to moist air. Upon dissolution ia excess water, hydrolytic degradation to phosphoric acid occurs the hydrolysis rate is highly temperature-dependent. At 25°C, the half-life for the formation of phosphoric acid from the condensed forms is several days, whereas at 100°C the half-life is a matter of minutes. 

In the fertilizer manufacturing scheme, the wet process phosphoric acid most commonly ensues from dissolution of sedimentary phosphate rock in sulfuric acid. Such acid solution contains around 1 g 1 1 uranium which is recovered as the byproduct. This task is accomplished by three well-proven extraction processes, some salient details of which are presented in Table 5.10. 

The chemical dissolution of silicon can be obtained in both liquid and gaseous media. The latter is known as dry etching or reactive ion etching (RIE) and is used in today s microelectronic manufacturing. However, wet processes related to silicon are also very important, as one third of the total number of process steps for the fabrication of today s integrated circuits involve... 

It must he mentioned that SC CO2 has been touted as the solvent of choice for potentially replacing a few, if not all, wet processes in the semiconductor lithography clean room of the future because of a number of inherent advantageous attributes. It is nonhazardous and inexpensive. It has high diffusivity (very comparable to that of a gas), which may aid in rapid effective dissolution. It has no surface tension since its liquid and vapor state are not simultaneously present, which may thus aid in mitigating pattern collapse issues of high aspect ratio features. Its solution properties can be tuned with minor adjustments of temperature and pressure. 

In Palabora, the apatite is decomposed as follows. Apatite is dissolved in a mixture of sulphuric acid and recycled dilute phosphoric acid from the wet process phosphoric acid plant. Most of the rare earths, (70-85 %) contained in the feed, end up in largely in phosphogypsum, which is formed in the dissolution reaction. The... 

The manufacturing process begins with the composition of a specific Cemented carbide powder mixture - tailored for the applicatiOTi. Scheelite or wolframite are the tungsten-cfuitaining minerals. Ammonium-Para Tungstate (APT) is the starting raw material of the production. The first step is a wet process involving a sequence of stepwise dissolutions, precipitations, and separations (Fig. 9). 

Properties Nonionic Toxicoiogy TSCA listed Uses Detergent, vise, builder, foaming agent, dispersant for detergent formulations, sanitizers controls dissolution rate of solid or block type hard surf, cleaners textile wet processing aid... 

Electrochemistry of LB films of fullerenes has been widely studied and remains the subject of much research effort from both theoretical and experimental approaches. Bard etal. have studied basic electrochemistry of Ceo fullerene LB films on an electrode in acetonitrile solutions [23]. The study indicated that reduction of the fullerene films could form insoluble films with incorporated electrolyte cations or lead to dissolution. The study on Cgo LB films has become a focus of considerable interest however, it is difficult to fabricate high-quality LB films of pure Cgo due to its intrinsic hydropho-bicity. Kajiyama et al. applied a multistep creep method as an LB technique for constructing a fairly homogeneous Ceo monolayer, which is regularly packed in a hexagonal array [44]. Kunitake etal. developed the electrochemical replacement method to form epitaxial adlayers of fullerenes on Au(lll) surfaces [45]. The wet process method consists of the transfer of Langmuir films of fullerene onto iodine-modified Au(lll) surfaces at an air-water interface followed by the electrochemical removal and replacement of iodine adlayers with fullerene adlayers in solution. The fullerene adlayers prepared by this method showed excellent quality and uniformity. A visuahzing... 

Important factors are the physical nature of the powder surface (particle size, pore size, porosity, environment, roughness, pretreatment). The dynamic wetting process is therefore influenced by the rates of ingredient dissolution and surfactant adsorption and desorption kinetics (25). 

Major routes of mineral phosphate (phosphate rock) into finished fertilizers are outlined in Fig. 11.5 and are discussed below. It is obvious from the figure that although phosphate rock is used directly in several major fertilizer production processes (ordinary superphosphate, nitric phosphates), most important processes require that the rock phosphate first be converted to phosphoric acid (H3PO4). Phosphoric acid production, then, is a very significant component of the phosphate fertilizer industry. The processes used for the production of fertilizer-grade phosphoric acid are known collectively as wet processes, and involve, initially, dissolution of the rock in sulfuric acid. (The highly specialized technology of wet-process acid production was discussed in Chapter 10.)... 

Uses Detergent, vise, builder, foaming agent, dispersant for detergent formulations, sanitizers controls dissolution rate of solid or block type hard surf, cleaners textile wet processing aid Regulatory Canada DSL Trade Names Rhodasurf TB-970 FLK Stearethate 40. See PEG-40 stearate Steaieth-7 carboxylic acid CAS 68954-89-2 59559-30-7 Uses Surfactant in cosmetics Steareth-11 carboxylic acid CAS 68954-89-2 Uses Surfactant in cosmetics Steareth phosphate... 

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