Recovery processes chemical

A fourth method for waste reduction in reactors focuses on spent catalyst wastes where recycling, controlling attrition, and limiting deactivation may reduce wastes. Consider the case of hydroprocessing catalyst wastes, which are extensively recycled to recover cobalt, molybdenum, nickel, vanadium, and alumina (Chemical and Engineering News, October 26, 1992, p. 20). More than a third of the domestic demand for vanadium is met via these recovery processes (Chemical and Engineering News, November 23, 1992,... 

Most coal-tar chemicals are recovered from coproduct coke ovens. Since the primary product of the ovens is metallurgical coke, production of coal chemicals from this source is highly dependent on the level of activity in the steel industry. In past years most large coke producers operated thein own coproduct recovery processes. Because of the decline in the domestic steel industry, the recent trend is for independent refiners to coUect cmde coal tars and light oils from several producers and then separate the marketable products. 

Brines. About 65% of the iodine consumed in the world comes from brines processed in Japan, the United States, and the former Soviet Union (see Chemicals frombrine). The predorninant production process for iodine from brines is the blow-out process, which was first used in Japan. Iodine is present in brines as iodide, and its concentration varies from about 10 to 150 ppm. As shown in Figure 3, the recovery process can be divided into brine clean-up, iodide oxidation to iodine followed by air blowing out and recovery, and iodine finishing. 

E. A. Knaggs and J. W. Hodge, Petroleum Sulfonates—Key Process Chemicals in Micellar Polymer Oil Recovery Systems, American Chemical Society,... 

High density tungsten alloy machine chips are recovered by oxidation at about 850°C, foUowed by reduction in hydrogen at 700—900°C. Typically, the resultant powders are about 3-p.m grain size and resinter readily. There can be some pickup of refractory materials used in furnace constmction, which must be controUed. This process is important commercially. Eor materials that may be contaminated with other metals or impurities, the preferred recovery process is the wet chemical conversion process used for recovery of tungsten from ores and process wastes. Materials can always be considered for use as additions in alloy steel melting. 

Recovery Process. Boron values are recovered from brine of Seades Lake by North American Chemicals Corp. In one process the brine is heated to remove some water and burkeite. The remaining brine is cooled to remove potassium chloride. This cooled brine is then transferred to another crystallizer where borax pentahydrate, Na2B40y 5H20, precipitates (18). In a separate process, boron is removed by Hquid—Hquid extraction followed by stripping with dilute sulfuric acid (19). Evaporator-crystallizers are used to recover boric acid [10043-35-3] H BO. In a third process, borax is recovered by refrigerating a carbonated brine. 

Recovery Process. Presently North American Chemical Co. at Seades Lake is the only significant producer in the wodd of sodium carbonate from brine (1,000,000 t/yr). 

Hydrogen sulfide Refinery gases, crude oil, sulfur recovery, various chemical industries using sulfur compounds Petroleum and chemicals Kraft pulping process Foul odor of rotten eggs irritating to eyes and respiratory tract darkening exterior paint... 

In the previous chapter, a comprehensive description was provided, from four complementary perspectives, of the process of how human errors arise during the tasks typically carried out in the chemical process industry (CPI). In other words, the primary concern was with the process of error causation. In this chapter the emphasis will be on the why of error causation. In terms of the system-induced error model presented in Chapter 1, errors can be seen as arising from the conjunction of an error inducing environment, the intrinsic error tendencies of the human and some initiating event which triggers the error sequence from this imstable situation (see Figure 1.5, Chapter 1). This error sequence may then go on to lead to an accident if no barrier or recovery process intervenes. Chapter 2 describes in detail the characteristics of the basic human error tendencies. Chapter 3 describes factors which combine with these tendencies to create the error-likely situation. These factors are called performance-influencing factors or PIFs. 

No solvent-stripping or recovery process is required, and product contamination by solvent or solvent impurities is avoided. The chemical reaction may take place in the melt... 

The application of a selective pyrolysis process to the recovery of chemicals from waste PU foam is described. The reaction conditions are controlled so that target products can be collected directly from the waste stream in high yields. Molecular beam mass spectrometry is used in small-scale experiments to analyse the reaction products in real time, enabling the effects of process parameters such as temperature, catalysts and co-reagents to be quickly screened. Fixed bed and fluidised bed reactors are used to provide products for conventional chemical analysis to determine material balances and to test the concept under larger scale conditions. Results are presented for the recycling of PU foams from vehicle seats and refrigerators. 12 refs. 

There is therefore extensive evidence that may be used to rationalize the occnrrence of bonnd residues in soils, and this phenomenon is of particnlar significance for agrochemicals. Snch processes influence not only their recovery by chemical procedures, but also their biological effect and their biodegradability (Calderbank 1989). The extent to which these principles are applicable to aquatic systems appears to have been established less frequently though it is plausible that comparable mechanisms exist in the environment. 

Enhanced oil-recovery processes include chemical and gas floods, steam, combustion, and electric heating. Gas floods, including immiscible and miscible processes, are usually defined by injected fluids (carbon dioxide, flue gas, nitrogen, or hydrocarbon). Steam projects involve cyclic steam (huff and puff) or steam drive. Combustion technologies can be subdivided into those that autoignite and those that require a heat source at injectors [521]. 

Xanthan exhibits an interaction with anionic surfactants (petroleum sulfate), which is a beneficial synergistic effect for mobility control in chemical-enhanced oil-recovery processes [1115]. 

The effectiveness of alkaline additives tends to increase with increasing pH. However, for most reservoirs, the reaction of the alkaline additives with minerals is a serious problem for strong alkalis, and a flood needs to be operated at the lowest effective pH, approximately 10. The ideal process by which alkaline agents reduce losses of surfactants and polymers in oil recovery by chemical injection has been detailed in the literature [1126]. 

The wettability of the rock is responsible for the behavior of a reservoir subjected to any oil-recovery process. Because the chemical composition of the mineral surface is mostly responsible for its wetting behavior, the relationship between wettability and chemical composition of the surface is key information. 

G. G. Hoffmann and I. Steinfatt. Thermochemical sulfate reduction at steam flooding processes— chemical approach. In ACS Petrol Chem Div Preprints, volume 38, pages 181-184. 205th ACS Nat Mtg Enhanced Oil Recovery Symp (Denver, CO, 3/28-4/2), February 1993. 

J. Song. A New Flux Correcting Method for Reducing Numerical Dispersion—Application to FOR (Enhanced Oil Recovery) By Chemical Processes (Reduction de la Dispersion Numerique par Correction desflux Massiques—Application au Probleme de la Recuperation d Hydrocarburespar Procedes Chimiques). PhD thesis, Paris VI Univ, 1992. 

Waste recovery and/or reuse. This comprises the identification and implementation of opportunities to recover process chemicals and materials for direct reuse or for reuse elsewhere through renovation or conversion technology. 

Recovery of process chemicals in coil coating plants is applicable to chromating baths and sealing rinses. Recovery techniques currently in use include ion exchange and electrochemical chromium regeneration.8-9... 

Although newer technologies are always under development, the basic kraft chemical recovery process has not been fundamentally changed since the issue of its patent in 1884. The stepwise progression of chemical reactions has been refined for example, black liquor gasification processes are now in use in an experimental phase. The precise details of the chemical processes at work in the chemical recovery process can be found in Smook s Handbook.12 The kraft chemical recovery process consists of the following general steps ... 

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