Recovery and Refining

Just as there are minor operational varianees from plant to plant in the separation and recovery of lead-bearing units, so it is for lead smelting and refining operations. Although smelters appear to have varying operations with the differing furnace types, the overall basie ehemieal reaetions are the same, as outlined below. 

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Recovery and Purification. AH processes for the recovery and refining of maleic anhydride must deal with the efficient separation of maleic anhydride from the large amount of water produced in the reaction process. Recovery systems can be separated into two general categories aqueous- and nonaqueous-based absorption systems. Solvent-based systems have a higher recovery of maleic anhydride and are more energy efficient than water-based systems. 

Uses are estimated to be manufacture of hydrosulfites and other chemicals, 40% pulp and paper, 23% food and agriculture (mainly corn processing), 14% water and waste treatment, 9% metal and ore refining, 6% oil recovery and refining, 4% and miscellaneous, including sulfonation of oils and as a reducing agent or antioxidant, 4% (270,271). 

In the next stage in the recovery and refining of tar acids, water and pitch ate removed from the cmde tar acids in a continuous-vacuum still heated by superheated steam or circulating hot oil. The aqueous phenol overhead distillate is recycled, the stream of once-mn tar acids is refined, and the phenoHc pitch bottoms are burned. 

A horizontal column is typified by the Brodie Purifier, which is shown schematically in Figure 26. Feed enters the column between recovery and refining sections, and crystals exit the refining section and pass through a purifying section. The purifying section is a wash column in which the crystals are contacted with melt generated at the bottom of the column. 

Product Recovery. Comparison of the electrochemical cell to a chemical reactor shows the electrochemical cell to have two general features that impact product recovery. CeU product is usuaUy Uquid, can be aqueous, and is likely to contain electrolyte. In addition, there is a second product from the counter electrode, even if this is only a gas. Electrolyte conservation and purity are usual requirements. Because product separation from the starting material may be difficult, use of reaction to completion is desirable ceUs would be mn batch or plug flow. The water balance over the whole flow sheet needs to be considered, especiaUy for divided ceUs where membranes transport a number of moles of water per Earaday. At the inception of a proposed electroorganic process, the product recovery and refining should be included in the evaluation to determine tme viabUity. Thus early ceU work needs to be carried out with the preferred electrolyte/solvent and conversion. The economic aspects of product recovery strategies have been discussed (89). Some process flow sheets are also available (61). 

C. Wright and R. L. Bruening, in Precious Metals Recovery and Refining (ed L. Manziek) Historical Publications, Austin, 1990, pp. 95-106. 

Minerals that have ion exchange capacity are also important in the discovery, recovery and refining of petroleum. In petroleum refining, they are important chiefly as catalysts and adsorbents. In petroleum recovery they mainly affect reservoir permeability. In the search for petroleum they are chiefly important in drilling fluids and as marker horizons. 

Product concentration, yield, and productivity are among the most important process variables in determining conversion costs.The concentration of the product influences its recovery and refining costs. Raw material costs are affected by the yield. Productivity, or the rate of product formation per unit of process capacity, helps determine the amount of capital, labor, and indirect costs assignable to the product. The influence of the medium on the interplay of these three variables cannot be ignored. 

Electrolytic refining. Lead of very high purity can be produced from the electrolytic process. Most electrolytic refineries utilize the Betts process [17]. In this process, lead bullion is cast into anodes and placed in an electrolytic cell which contains an electrolyte of fluorosilicic acid and lead fluorosilicate. The cathode is a thin sheet of high-purity lead referred to as the starter sheet . Lead is deposited on the cathode while the impurities form an adherent, but porous, slime layer on the anode. The slimes are collected for recovery and refining as they contain valuable impurities such as silver, gold, copper, and bismuth. 

Using these assumptions, the jacketed cooling areas required for the recovery and refining sections are... 

Clathrate hydrates of natural gases are of great importance in current research within the petroleum industry. The natural reserves are a potential source of energy, as well as a potential environmental hazard, and the accidental formation of hydrates during recovery and refinement of oil and gas is both an economical and ecological liability. Clathrate hydrates also present an opportunity for novel storage and transportation technologies. 

Processes used in recovery and refining and subsequent storage conditions are the main factors affecting the quality of edible fat or oil. A number of analytical methods are available for assessing the quality and deterioration of fat or oil. 

The reactive detoxifying emulsions (RDE) (Stambouli, 2006) are water-oil-water multiple emulsions. This detoxification emulsion technique is an emerging technology, and is directly based on a more known solvent extraction (SE) process that has been extensively applied for the selective recovery and refining of a wide variety of solutes (metal ions, pollutants, toxics, etc.) in hydrometaUurgy and nuclear industry. 

Although this is somewhat generalized, here are the dynamics we have often encountered with oil recovery and refining ... 

Numerous books, research papers, and studies have been published in the area of oil recovery and refining, so this is no more than a cursory overview of the considerations of Make when it comes to specialty oil crops. However, the importance of planning and avoiding unpleasant surprises can perhaps be illustrated and put into some economic context as follows. 

Speight, J.G. 2004. Petrolenm asphaltenes. Part 2. The effect of asphaltenes and resin constituents on recovery and refining processes. Oil Gas Sci. Technol. 59 479-488. 

Oily additives are used in various technologies (e.g., paper and pulp production, ore flotation, fermentation) and commercial products (detergents, paints, some pharmaceuticals) to avoid the formation of an excessive foam, which would impede the technological process or the product application [1-3]. In other cases (oil recovery and refinement, shampoos, emulsions for metal processing machines) oil drops are present, without being specially introduced for foam control, and can also affect the foamability of the solutions. Small fractions of hydrophobic solid particles of micrometer size, such as hydrophobized silica or alumina, plastic grains, or stearates of multivalent cations, are often premixed with the oil because the solid-oil compounds obtained exhibit a much stronger foam destruction effect than the individual components taken separately [4-8]. Such oily additives are termed antifoams in the literature and can be based on hydrocarbons, poly-dimethylsiloxanes (PDMSs, silicone oil) or their derivatives [1,4]. 

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