Waste Plastics Processing

Effective engineering design of the cracking reactor for waste plastic processing is very important since the carbonaceous solid residue is one of the cracking products (levels up to 10% or more) and its continuous removal from the reactor is necessary to ensure profitable running. Stirred vessel reactors which have augers in the bases to facilitate continuous char removal are presented. 

Economic efficiency of waste plastics processing depends on the methods of their selection and preparation for processing as well as the cost of thermal or catalytic treatment, i.e. the cost of investment and exploitation of the cracking plant. For instance the main characteristic of fluid-bed reactors is the possibility of exploitation of large-scale units (at least 50000 tons or more per year), low cost of exploitation, but accompanied by large investment and feed delivery costs. And on the other hand, smaller reactors can be built on a smaller scale, a few thousand tons per year output, lower investment costs and lower feed deliveries (processing of local wastes in limited area), but operated with larger exploitation costs. 

Local autliority control of au pollution covers a second tier of less-polluting processes. Incinerators for waste chemicals, or waste plastic arising from their manufacture, and other waste incinerators dependent upon size are, however, subject to both the BATNEEC and BPEO requirements under the IPC regime. 

Technology Descriptions The use of thermoplastic solidification systems in radioactive waste disposal has led to the development of waste containment systems that can be adapted to industrial waste. In processing radioactive waste with bitumen or other thermoplastic material (such as paraffin or polyethylene), the waste is dried, heated and dispersed through a heated, plastic matrix. The mixture is then cooled to solidify the mass. 

The process requires some specialized (expensive) equipment to heat and mix the waste and plastic matrices, but equipment for mixing and extruding waste plastic are commercially available. The plastic in the dry waste must be mixed at temperatures ranging from 130 to 230 C, depending on the melting characteristics of the material and type of equipment used. 

Recycling can include chemical recycling. This involves plastics waste being processed chemically, either by cracking or depolymerisation, to... 

CHEMICAL RECYCLING PROCESS FOR WASTE PLASTICS USING SUPER-CRITICAL WATER... 

This comprehensive article supplies details of a new catalytic process for the degradation of municipal waste plastics in a glass reactor. The degradation of plastics was carried out at atmospheric pressure and 410 degrees C in batch and continuous feed operation. The waste plastics and simulated mixed plastics are composed of polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile butadiene styrene, and polyethylene terephthalate. In the study, the degradation rate and yield of fuel oil recovery promoted by the use of silica alumina catalysts are compared with the non-catalytic thermal degradation. 9 refs. lAPAN... 

This paper outlines waste plastic liquefaction technology, and discusses its use in the operation of a demonstration plant. The following aspects are considered plastics suitable for liquefaction, basic principals of liquefaction technology, the liquefaction process, examples, results, and conclusions. 4 refs. 

Polymers have inherently high hydrocarbon ratios, making liquefaction of waste plastics into liquid fuel feedstocks a potentially viable commercial process. The objective is to characterise the thermal degradation of polymers during hydrogenation. LDPE is studied due to its simple strueture. Isothermal and non-isothermal TGA were used to obtain degradation kinetics. Systems of homopolymer, polymer mixtures, and solvent-swollen polymer are studied. The significant variables for... 

An Ecoprofile is an assessment of the environmental and resource impacts of a waste disposal process. This paper describes ecoprofiles for six different ways of disposing the plastic fraction in municipal solid waste -two material recycling processes that include separation of the plastic waste, material recycling without separation of the plastic waste, pyrolysis, incineration with heat recovery, and landfill. 17 refs. 

An account is given of the chemical recycling activities of BASF in a pilot plant at Ludwigshafen in Germany, where mixed plastics waste is processed to obtain hydrochloric acid, oil, gas, naphtha, aromatics and alpha-olefins. 

This article provides brief information from a study carried out in the Netherlands, which revealed that combustion with energy recovery is the most economical way of processing waste plastics, whilst mechanical recycling is the most environmentally attractive option. 

This article examines the progress being made in methods of converting plastics into chemical feedstocks. BASF is setting an ambitious pace with its feedstock recycling programme with a 1996 target date for a 300,000 t/y plant to be fed with waste plastics from the DSD/DKR system. The process uses a confidential catalyst system and is described as similar to pyrolysis. A 15,000 t/y pilot plant... 

Energy recovery to reduce the amount of waste plastics going to landfill is shown by eco-balance studies to be more environmentally beneficial than recycling, it is reported. Advantages of the method and statistics to show current levels of activity are reported, and also the investment required by a company to operate such a process, and the running costs involved. 

Industrial processes for recycling have been developed which take advantage of reactively separating hydrolysable polymers from nonhydrolysable waste plastics [651]. 

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