Some barriers to the use of materials recovered from municipal solid waste
Abstract Municipal solid waste (MSW) contains materials which could be put to good use, yet it continues to be discarded, which suggests that it contains little or nothing of value under current conditions. This paper discusses the technical reasons for the lack of commercial interest in recovering materials from MSW. After examining the nature of the salvage industry and trends in the use of materials, the paper considers the characteristics of secondary materials, the properties required of them, and the scope for increased salvage activity. The market prospects are described for waste paper, ferrous and non- ferrous scrap, glass and polymers.
The recycling of metals—I. Ferrous metals
Abstract This paper treats the recycling of ferrous metals as an integral part of the iron and steel industry. The flows of home, prompt industrial and old scrap are analyzed. The industrial organization of ferrous scrap recycling is also described. Scrap is one of the two major raw materials of the iron and steel industry. The various steelmaking processes however, consume scrap in different ratios to other raw materials in the charge. The price sensitivity of scrap and the growing importance of automotive scrap are also considered. The advantages of using scrap in steelmaking include savings of energy, pollution abatement measures and processing which would otherwise be required in producing raw iron in the blast furnace. As a disadvantage, scrap can cause technical difficulties by introducing impurities into the steel. The paper also deals with international aspects of ferrous scrap markets. Finally, it assesses the supply-demand relation as a function of such developments as the shift in the balance of steelmaking processes, the adoption of continuous casting, the use of prereduced ores and further improvements in the processing of ferrous scrap.
Trouble-shooting dual arch impressions.
Dual arch impression techniques enable the dentist to capture an impression of the prepared tooth, the opposing teeth and the occlusal registration in one procedure. This saves chair time and impression material.