Recovery byproducts

Cryogenic processes using turboexpanders facilitate high levels of ethylene recovery from refinery gas while producing byproducts of hydrogen- and methane-rich gas. In a cryogenic process, most of the ethylene and almost all of the heavier components are liquified and ethylene is separated from this liquid. 

Out of the 900 million tons of coal produced in the United States for domestic purposes in 1992, about 34 million tons were used for coking [10]. The overw helmmg majority of coal is consumed by the electric utilities. Nevertheless, in 1990, the United States steel industry required about 23 million tons of coke which was produced by the byproduct recovery slot oven [15] For a typical blast furnace, this translates to 0 5 tons of coke per ton of iron metal. 

Coal-based pitches are predommantly byproducts of metallurgical coke operations in recovery-type coke ovens. The volatile products from the coke oven are recovered and processed, in simplest terms, into gas, light oils, and tar. The quantity and character of the materials are influenced by the type of coal charge, the design of the cokmg equipment, and the temperature and time profile of carboni2ation. Table 1 shows a typical yield of products from the... 

Absorption Process for Rejection of Reactor Byproducts Recovery of Monomers from Waste Gas Streams in Olefin Polymerization Process, U.S. Patent 5.681.908. Oct. 28. 1997. 

Etliylene production involves liigh temperatures (1500°F) in tlie pyrolysis section and cryogenic temperatures in tlie purification section. The feedstocks, products, and by-products of pyrolysis are flaimnable and pose severe fire liazards. Benzene, wliich is produced in small amounts as a byproduct, is a known carcinogen. Table 21.7.1 summarizes some of the properties of etliane (feedstock) and tlie product gases. Figure 21.7.1 shows a simplified schematic diagram of the pyrolysis and waste heat recovery section on an etliylene plant. 

More than 200 ores are known to contain cobalt but only a few are of commercial value. The more important are arsenides and sulfides such as smaltite, C0AS2, cobaltite (or cobalt glance), CoAsS, and linnaeite, C03S4. These are invariably associated with nickel, and often also with copper and lead, and it is usually obtained as a byproduct or coproduct in the recovery of these metals. The world s major sources of cobalt are the African continent and Canada with smaller reserves in Australia and the former USSR. All the platinum metals are generally associated with each other and rhodium and iridium therefore occur wherever the other platinum metals are found. However, the relative proportions of the individual metals are by no means constant and the more important sources of rhodium are the nickel-copper-sulfide ores found in South Africa and in Sudbury, Canada, which contain about 0.1% Rh. Iridium is usually obtained from native osmiridium (Ir 50%) or iridiosmium (Ir 70%) found chiefiy in Alaska as well as South Africa. 

The basic advantages of this process are (a) elimination of a mechanical device (recycle gas compressor) for controlling the adiabatic temperature rise, (b) combination of CO shift with methanation, (c) significant increase in byproduct steam recovery, and (d) significant capital advantages. 

Waste HBr is a common byproduct of organic brominations. Frequently, this waste is neutralized with caustic, the resulting sodium bromide salt is discharged, and valuable bromine is lost. The economic advantages of recovery and recycle of this HBr have long been recognized (refs. 1, 3). In practice, recovery typically takes the form of conversion of the HBr to clear drilling fluids or alkylbromides (ref. 4) as shown in equations 1 and 2. 

Product purification not only includes recovery of the catalyst. It also consists of removal of co-catalysts, decomposition products of the ligands, unconverted reactants, and byproducts. The latter two, of course, are not specific for homogeneous catalysis. 

Various bacterial species have proven useful in MEOR. The principle is based on the species biochemical byproducts produced, such as gases, surfactants, solvents, acids, swelling agents, and cosurfactants, which facilitate the displacement of oil. In field experiments, in situ fermentation is often desirable for producing a great quantity of gases. Clostridium hydrosulfuricum 39E was found to have surface-active properties during simulated enhanced oil recovery experiments [1874]. 

Table 5.10 Salient features of uranium recovery processes as a byproduct of phosphatic fertilizer industry.

Has consideration been given to the recovery of materials through the application of integrated source control on a process-by-process basis, for example, direct or indirect recovery of materials by sidestream treatment, process solution enhancement through sidestream removal of contaminants, conversion of waste to byproduct of value ... 

Benzene releases in byproduct recovery operations Naphthalene residues generated in the final cooling tower Sulfur and sulfur compounds recovered from coke oven gas Wastewater from cleaning and cooling (contains zinc, ammonia still lime, decanter tank tar, or tar distillation residues)... 

In the U.S., three pieces of federal legislation that were passed from 1969 to 1980, and the implementing rules and regulations that followed, initiated a series of fundamental changes in the management of waste and byproduct materials. They presently affect the way in which regulatory agencies address waste and byproduct material use. These acts include the National Environmental Policy Act (NEPA, 1969), the Resource Conservation and Recovery Act (RCRA, 1976, 1980), and the Comprehensive Environmental Response, Compensation, and Liabilities Act (CERCLA) or Superfund (1980). 

Byproducts are materials that are not one of the intended products of a production process. An example is the sediment remaining at the bottom of a distillation column. Byproduct is a catch-all term and includes most wastes that are not spent materials or sludges. Listed byproducts are solid wastes when reclaimed used in a manner constituting disposal burned for energy recovery, used to produce a fuel, or contained in fuels or accumulated speculatively. On the other hand, characteristic byproducts are not solid wastes when reclaimed, unless they are used in a manner constituting disposal burned for energy recovery, used to produce a fuel, or contained in fuels or accumulated speculatively (Table 13.1). 

To understand how such computer packages function, consider the simple flowsheet in Figure 13.13a. This involves an isomerization of Component A to Component B. The mixture of A and B from the reactor is separated into relatively pure A, which is recycled, and relatively pure B, which is the product. No byproducts are formed and the reactor performance can be characterized by its conversion. The performance of the separator is to be characterized by the recovery of A to the recycle stream (rA) and recovery of B to the product (rB). 

Concentrated wastes can result from bad product being made, unsalable byproducts, contamination of products, laboratory wastes, and previously mentioned pollution-abatement steps that concentrate the pollutants. Whatever their source, if recovery is impossible, they must be eliminated. The most common means are incineration or pyrolysis followed by landfill operations and/or compacting. As... 

Trace Rhodium Recovery from Product or Byproduct Streams. As will be discussed later, there are what might be viewed as the ultimate rhodium recovery methods in which the organic matrix is burned, the rhodium recovered as an ash, then processed through a precious metal refinery before conversion into a catalyst precursor. Once rhodium is processed into an ash, there is significance expense associated with its conversion to a suitable catalyst precursor. Therefore, technologies which permit capture and reuse or reactivation and reuse are strongly preferred over more extreme procedures. 

Humphrey DN, Eaton RA (1993) Tire chips as a subgrade insulation - field trial. Symposium proceedings Recovery and Effective Reuse of Discarded Materials and Byproducts for Construction of Highway Facilities. Federal Highway Administration, FHA, 11... 

The effluent from the reactor is cooled in a heat exchanger. The EO, byproducts, and unreacted ethylene are separated in a water-wash column in a manner just like the solvent recovery process described in Chapter 2. The EO is absorbed by the water while the by-products (mainly CO2, plus the everpresent cats and dogs in small quantities), and unreacted ethylene are not. The EO/water solution is then steam-stripped and purified by fractionation. 

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