Recovered resources

Processing Techniques for Solid Wastes Processing techniques are used in solid-waste-management systems to (I) improve the efficiency of the systems, (2) to recover resources (usable materials), and (3) to prepare materials for recoveiy of conversion produc ts and energy. The more important techniques used for processing solid wastes are summarized in Tables 25-61 and 25-62. 

Producing companies locate the subsurface petroleum resources recover the oil, gas or condensate and then market the recovered resource to customers. These activities involves planning and carrying out exploration, drilling and well completion, and the production activities. 

The waste audit program is Intended to provide assistance to California s small quantity generators of hazardous waste. This is accomplished by issuing contracts to evaluate waate reduction opportunities in industries typically comprised of small to medium businesses. Waste-generating operations are studied to identify potentials for reducing waste, recycling or recovering resources, or alternative treatment measures. The economic feasibilities of the various alternatives are analyzed, and the study results are compiled in a final waste audit report. 

Basdere B, Seliger G (2003) Disassembly factories for electrical and electronic products to recover resources in product and material cycles. Environ Sci Technol 37(23) 5354-5362... 

At this point, it seems to me important to note that the greatest uncertainties are not derived from the scientific performance assessment of the confinement barrier systems but clearly from the possibilities of disruption by human intrusion. Even deliberate human intrusion for the sake of recovering resources, such as plutonium left in spent fuel, cannot be excluded as technically impossible. If at the time when repositories for spent fuel will have to be closed and sealed, i. e. in 100 to 150 years from now, if then the non-proliferation regime will still have the same political importance as today, then technical means will have to be implemented to allow Nations to receive international confirmation of the continued presence of any fissile material which is left over in the repositoiy, or - as the case may be - that such material is retrieved for peaceful purposes only. 

As the resources and energy reserve of the earth are becoming scarce, Science/Technology must first minimize their consumption. Science/Technology must be employed to recover resources already consumed and released into the ocean and atmosphere, to recycle resources, and further to create new resources and energy supply. Also, technology to repair the damaged natural environment or to prevent its further devastation must be developed. 

Resources for Potash Fertilizers. Potassium is the seventh most abundant element in the earth s cmst. The raw materials from which postash fertilizer is derived are principally bedded marine evaporite deposits, but other sources include surface and subsurface brines. Both underground and solution mining are used to recover evaporite deposits, and fractional crystallization (qv) is used for the brines. The potassium salts of marine evaporite deposits occur in beds in intervals of haUte [14762-51-7] NaCl, which also contains bedded anhydrite [7778-18-9], CaSO, and clay or shale. The K O content of such deposits varies widely (see Potassium compounds). 

Phosphorite Deposits. Sedimentary phosphorites contain low concentrations of uranium in fine-grained apatite. Uranium of this type is considered an unconventional resource. Significant examples of these uranium ore types include the U.S. deposits in Elorida, where uranium is recovered as a by-product, and the large deposits in North African and Middle Eastern countries (16). 

Domestic. Estimates of U.S. uranium resources for reasonably assured resources, estimated additional resources, and speculative resources at costs of 80, 130, and 260/kg of uranium are given in Table 1 (18). These estimates include only conventional uranium resources, which principally include sandstone deposits of the Colorado Plateaus, the Wyoming basins, and the Gulf Coastal Plain of Texas. Marine phosphorite deposits in central Elorida, the western United States, and other areas contain low grade uranium having 30—150 ppm U that can be recovered as a by-product from wet-process phosphoric acid. Because of relatively low uranium prices, on the order of 20.67/kg U (19), in situ leach and by-product plants accounted for 76% of total uranium production in 1992 (20). 

Fluid deposits are defined as those which can be recovered in fluid form by pumping, in solution, or as particles in a slurry. Petroleum products and Frasch process sulfur are special cases. At this time no vaUd distinction is made between resources on the continental shelf and in the deep oceans. However, deep seabed deposits of minerals which can be separated by differential solution are expected to be amenable to fluid mining methods in either environment. 

SASOL. SASOL, South Africa, has constmcted a plant to recover 50,000 tons each of 1-pentene and 1-hexene by extractive distillation from Fischer-Tropsch hydrocarbons produced from coal-based synthesis gas. The company is marketing both products primarily as comonomers for LLDPE and HDPE (see Olefin polymers). Although there is still no developed market for 1-pentene in the mid-1990s, the 1-hexene market is well estabhshed. The Fischer-Tropsch technology produces a geometric carbon-number distribution of various odd and even, linear, branched, and alpha and internal olefins however, with additional investment, other odd and even carbon numbers can also be recovered. The Fischer-Tropsch plants were originally constmcted to produce gasoline and other hydrocarbon fuels to fill the lack of petroleum resources in South Africa. 

Refuse-Derived Fuel. Many processing faciUties divert a portion of the material that is not recovered for recycling to waste-to-energy plants, also referred to as resource recovery faciUties, where the material is employed as fuel. The processes involved in the production of refuse-derived fuel (RDF) are outlined in Figure 4 (23). Nine different RDFs have been defined, as Hsted in Table 3 (24). There are several ways to prepare RDF-3, which is perhaps the most popular form and is the feed used in the preparation of densified refuse-derived fuel (d-RDF). AH forms of RDF are part of the broader set of waste-derived fuels (WDF), which includes various waste biomass, eg, from silvaculture or agriculture (see Fuels frombiomass Fuels fromwaste). 

Economic Analysis. The economic success of recycling programs is subject to the following inequaUty where X = the cost to recover recyclable materials, Y = the cost of disposal, and Z = the value of the resource recovered. 

A rather impressive Hst of materials and products are made from renewable resources. For example, per capita consumption of wood is twice that of all metals combined. The ceUulosic fibers, rayon and cellulose acetate, are among the oldest and stiU relatively popular textile fibers and plastics. Soy and other oilseeds, including the cereals, are refined into important commodities such as starch, protein, oil, and their derivatives. The naval stores, turpentine, pine oil, and resin, are stiU important although their sources are changing from the traditional gum and pine stumps to tall oil recovered from pulping. 

Ocean Nodules. A less conventional copper resource consists of deep-sea ferromanganese nodules. These nodules are primarily manganese, but some deposits contain over 1% copper. The nodules occur at many ocean sites, but the most valuable deposits are found in the Pacific Ocean. Although a number of companies are studying methods for recovering values from this source, copper resources from nodules must be considered tentative. World resources are estimated at 0.7 biUion metric tons (8) (see Ocean raw materials). 

Mechanical Component Separation Component separation is a necessaiy operation in the recovery of resources from sohd wastes and in instances when energy and conversion products are to be recovered from processed wastes. Mechanical separation techniques that have been used are reported in Table 25-61. 

Recycling Technical Assistance Partnership National Network A national information-sharing resource designed to help businesses and manufacturers increase their use of recovered materials. 

The terms oil production and gas production refer to rates of extraction of liquid and gaseous hydrocarbon materials from natural underground deposits. Reserves and resources, on the other hand, refer to amounts of oil and gas that are present in the deposits, the difference between reserves and resources being whether or not the amounts can be economically recovered under current conditions. Supply refers to the amount of a product that becomes available for... 

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