Economics Price, Recycling

Chemical properties Small volume pressure, low vapor pressure, compatibility with other materials, long-term chemical stability, nontoxic, no fire hazard Economical Low price, recyclable, abundant... 

In view of the high price of crude oil, economical material recycling appears feasible. Control over critical contaminants, in particular during firing to obtain... 

Nylon generally performs the best among all synthetic fibers as carpet face yarn, but it is also the most expensive. Typical price per kilogram for the plastic resins are nylon 2.50, polyester 1.20, and polypropylene 0.75. This price list provides a perspective on the economics of recycling as well. For example, if it takes the same processing effort to convert the fiber into resin, an operation on nylon would be most profitable. This also explains why most of the recycling effort is on nylon recovery. 

With ever-increasing oil prices, recycled plastics are becoming an economical alternative for the production of a wide range of commodity plastic parts. Polyolefinic polymers, such as polyethylene (PE) and polypropylene (PP), contain approximately 14% hydrogen these materials could provide the hydrogen required for thermal coprocessing with biomass, which could lead to an increase of the liquid production of oligomers or short chain polymeric materials. 

Phenolics are consumed at roughly half the volume of PVC, and all other plastics are consumed in low volume quantities, mosdy in single apphcation niches, unlike workhorse resins such as PVC, phenoHc, urea—melamine, and polyurethane. More expensive engineering resins have a very limited role in the building materials sector except where specific value-added properties for a premium are justified. Except for the potential role of recycled engineering plastics in certain appHcations, the competitive nature of this market and the emphasis placed on end use economics indicates that commodity plastics will continue to dominate in consumption. The apphcation content of each resin type is noted in Table 2. Comparative prices can be seen in Table 5. The most dynamic growth among important sector resins has been seen with phenoHc, acryUc, polyurethane, LLDPE/LDPE, PVC, and polystyrene. 

Since the bulk of butadiene is recovered from steam crackers, its economics is very sensitive to the selection of feedstocks, operating conditions, and demand patterns. Butadiene supply and, ultimately, its price are strongly influenced by the demand for ethylene, the primary product from steam cracking. Currently there is a worldwide surplus of butadiene. Announcements of a number of new ethylene plants will likely result in additional butadiene production, more than enough to meet worldwide demand for polymers and other chemicals. When butadiene is in excess supply, ethylene manufacturers can recycle the butadiene as a feedstock for ethylene manufacture. 

To be fair, it should be realized that if a catalyst must be recycled for economic reasons, the recycling efficiency compared to the nonfunctionalized catalyst must be higher in order to compensate for the increased price of the fluorous catalyst itself. However, every recycling technique has its own cost that must be evaluated for each specific case. 

In those jurisdictions where money is specifically collected from consumers to underwrite the costs of recycling plastic containers, funds may be available to offset some costs of depolymerization. If bottles are provided at no cost at the sorting/baling facility, an economically attractive venture can be contemplated, but still at a large scale. Securing the feed on a long-term basis at a favorable price will require significant co-operation. 

From an economic point of view, the cost assessment of the recyclate depends primarily on the price retained for the waste. The recycling cost is in the range of ... 

The process flow sheet was first tested for direct leaching of steel mill flue dust and production of zinc metal by electrowinning. The tests were performed in a continuously operating pilot plant, producing 10-20 kg/day zinc metal. The same pilot plant was then used for treating copper/zinc-rich brass mill flue dust in a closed loop operation, recycling all the zinc solvent extraction raffinate to the copper circuit leach section. In the zinc circuit leach section, only the amount of zinc rich dust necessary for neutralization of the copper solvent extraction raffinate was used. The results obtained from the pilot plant tests indicated contamination problems within the solvent extraction loops. The estimation of economic data showed a weak return on the assets compared with the alkali route, and sensitivity toward the raw material price. 

An economic analysis can show that the most effective factor in reducing the manufacturing costs could be replacing the propene by propane, which is 30% cheaper. An industrial process is attributed to Asahi [18]. The key competitive element is the availability of a suitable catalyst. Despite intensive research the performance of today s catalysts remains rather modest. The conversion should be kept low, below 50%, while the selectivity cannot be pushed beyond 60%. Because the recycle of unconverted propane and larger spectrum of byproducts the advantage of lower price seems to be not sufficient for a technological breakthrough. 

A less effective, but more economically viable method, would be to recycle all low-value hydrocarbon by-products to the cracker furnace. This particularly focuses on methane which within the confines of an operation is typically valued relative to the fuel oil price. However, this equally applies to ethane and propane which are generally recycled to the feedstock side of the cracking furnace. Depending on the relative value, it may be optimal for minimising carbon emissions in some operations to use ethane as a fuel rather than a feedstock. 

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