Resource Recovery and Conservation最新文献

A mathematical model was developed for prediction of the practicability of building and operating large centrally located anaerobic digesters for producing methane gas from animal manure. The assumptions were that the manure would be collected from the feedlots and that the product gas would be supplied to an existing pipeline.

The model takes account of the farm locations and calculates transportation costs for various numbers of digesters. Digester sizes for each distribution are computed and installation and operating costs are found. Revenue was then determined on the basis of methane production and fertilizer value recovery.

The utility of the model is shown through an application study of farms in southwestern Ontario where many relatively small feedlots exist. The results of the study indicate a gas production cost of roughly $0.18/m³ ($ 5.00/mscf).

This paper calculates both the energy and raw materials requirements of aluminium production in the United Kingdom in 1976, tracing the production sequence from raw materials in the ground through to ingot. The gross energy requirement for the production of primary aluminium ingot is shown to be 308.31 MJ/kg and a detailed breakdown by fuel type and contributing operation is given. The calculations are based almost entirely on data collected directly from the relevant industries.

A growing environmental awareness, backed by legislation, and the search for energy saving have necessitated the development of more efficient methods for disposing of scrap tyres. Alternative tyre disposal techniques are briefly reviewed and the implication of pyrolysis as a potentially valuable addition to treatment procedures is discussed, with particular emphasis on the cross-flow system developed by Warren Spring Laboratory and Foster Wheeler Power Products Limited.

A simple, inexpensive scheme was developed to recover silver and mercury from silver-tin dental amalgam waste. Direct distillation of the amalgam under reduced pressure yielded 99.22 ± 0.68% pure mercury with 87.7 ± 3.6% recovery. It was shown that the recovered mercury could possibly be further purified to 100.03 ± 0.14% by redistillation. Silver was isolated from the residue as silver chloride, which was then converted to silver oxide and diamino-silver(I) complex for chemical reduction by glucose and electrochemical reduction, respectively. The former method recovered 92.4 ± 2.5% silver of 99.5 ± 1.1% purity; the latter yielded silver with a slightly lower recovery, 89.9 ± 3.1%, but higher purity, 99.99 ± 0.17%. Parameters governing the two recovery routes were also investigated.

This paper presents the results of a field test program to evaluate and characterize the performance of shredders used for the size reduction of solid waste. In all, tests were conducted on seven horizontal hammermills, one vertical hammermill, and one vertical ring shredder at six commercial sites (Appleton, Wisconsin; Ames, Iowa; Cockeysville, Maryland; Great Falls, Montana; Tinton Falls, New Jersey; and Odessa, Texas). Both two-stage size reduction (Ames) and single-stage size reduction were studied as part of this work. Evaluation and interpretation of the data have resulted in the development of analytical relationships among the comminution parameters, the development of methods for characterizing shredder performance, and the establishment of levels of performance with respect to energy consumption and hammer wear associated with size reduction of solid waste.

This is the second and final part of a survey of the sources, amounts and methods of disposal of major mining, industrial and municipal wastes and by-products available in the 48 conterminous states of the United States. Their present and potential uses as construction materials are also considered. Part I covered mining wastes, waste and by-products from the phosphate, aluminium and cement industries, sulfate wastes, and by-products from coal combustion [1]. Part II covers metallurgical and mineral slags, municipal wastes, and wastes from emerging technologies.