ISSN:0094-243X    

DOI:10.1063/1.30806

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Mining and agriculture are the fundamental industries that convert natural resources into useable forms. Mining and modern agriculture are inextricably interlinked because modern agriculture is heavily dependent upon the use of machinery, power, and fertilizers ‐ all of which are mineral based products, and in some applications mineral and agricultural products are mutually substitutable. Steel production is common denominator for assessing demand for many minerals, and in the last 2–1/2 decades world steel production has grown at an annual rate of about 5–1/2%. Currently, the United States uses about 4 billion tons ‐ 40,000 pounds per person ‐ of new mineral supplies each year, about equally divided between the mineral fuels and other mineral materials. The value of energy and processed materials of mineral origin used in the U.S. is estimated to exceed $270 billion per year. Rising world population, coupled with aspirations for higher living standards, points to steadily increasing world demand for mineral materials. Studies by the U.S. Bureau of Mines show that the ratio of recoverable world mineral reserves to cumulate demand over the next few decades is satisfactory for most mineral materials. However, if world mineral production is to keep pace with demand, there must be increased efforts to find, mine, beneficiate, process, and recycle mineral materials, and there must also exist politico‐economic climates that encourage long‐term mineral development while also making appropriate provisions for humanitarian and envronmental concerns.

ISSN:0094-243X    

DOI:10.1063/1.30801

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The paper attempts to respond to the question of whether materials economists can provide useful cues to technological R?D in materials. Doubts are expressed that there are specialists that can truly be called ’’materials economists’’ and that the profession as a whole has seriously analyzed the economics of materials problems. Hypothetical lists are drawn up of characteristics that would make a material ’’deal’’ from the materials scientist’s and from the economist’s viewpoint. A number of the economic characteristics are analyzed with respect to the knowledge economists presently have of their presence or absence in any given material. The answer is disapointing. Hope is expressed that the visibility of the materials problem will attract economic analysis and that the technologists will raise questions to stimulate this research.

ISSN:0094-243X    

DOI:10.1063/1.30816

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

This paper uses the materials cycle to assess the implications for science and technology of finite and increasingly costly supplies of resources. The analysis is based upon the economic view that lagging productivity and increases in materials prices pose a more serious threat to resource adequacy than depletion. The resource question is discussed in terms of development of domestic minerals, trade in raw materials and finished goods, environmental constraints, recycling, and investment in materials industries. The implications for science and technology of each of these factors is considered in terms of basic trends. The paper concludes that efficient use of materials, defined not only in terms of quantity of material per functional output, but also value added per unit of input offers the best prospect for resource adequacy in the foreseeable future. According to this view, the Nation needs to devote more of its scientific and technological resources to studies of corrosion, wear, degradation, and failure of materials, as well as to efficient methods for nondestructive testing of materials. Improved understanding in these areas would conribute to the development of a scientific basis for the most efficient use of materials in terms of performance and expected lifetime.

ISSN:0094-243X    

DOI:10.1063/1.30817

出版商:AIP    

年代:1976

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.30818

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Beginning with mining some 400 years ago, the author traces mining’s accelerating swing from labor intensive to capital intensive and shows the reasons for it.Illustrating the basic energy requirements, the author indicates why mechanization has now swept world mining.Critical of the exotic methods currently being extolled, the author contends that the primary gains in mining for the rest of this century will be made through improvements to and greater application of current mechanization, rather than exotics or automation.Calling for intensifying the application of scientific methodology to improve current machine‐rock interface materials and to develop new and better materials, the author expresses a real need for increasing the application of current sciences to mining needs.He concludes, however, that except for in situ mining it is unlikely that mining will ever become a science. Because of the irregular variations in the earth’s crust from whence ore comes, man’s intelligence will always be required at the working face, and thus mining as it is known today will always be an art.

ISSN:0094-243X    

DOI:10.1063/1.30819

出版商:AIP    

年代:1976

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.30820

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

This article examines how the adaptation of materials supply systems to resource scarcity and especially energy scarcity can be aided by physical analyses. Two kinds of analyses are examined: thermodynamic, which is still limited in its capabilities but will become increasingly more helpful; and process energy analysis, which can be used to guide R and D, to study technological drift, and to assess potential measures for energy conservation.

ISSN:0094-243X    

DOI:10.1063/1.30798

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Approximately 150 million tons of municipal solid waste are collected each year in the United States. This refuse contains many valuable materials that can be used again provided they are separated and purified sufficiently. The present paper reviews the sorting techiniques that apply to this problem with special emphasis on the recovery of nonmagnetic metals. Only approximately 0.5 to one percent of the municipal solid waste consist of such metals (mostly Aluminum), but because of their relatively high scrap value (up to $300/ton) they constitute a significant portion of the reclaimable value. A new technique for the recovery of nonmagnetic metals from municipal solid waste is described. The separator consists of an inclined ramp on which the nonmagnetic metals are deflected to one side as they slide down. Deflection results from eddy currents induced by permanent magnets embedded in the ramp surface. A detailed theory has been developed that allows prediction of the deflection of metallic particles from the straight‐down path as a function of all the relevant physical parameters. The theoretical predictions have been tested by comparison with experimental results. Tests have also been conducted on the heavy‐fraction remaining after air classification of municipal solid waste.

ISSN:0094-243X    

DOI:10.1063/1.30799

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

This paper discusses fundamental phenomena involved in the corrosion of metals in ionizing solvents. General subjects covered include corrosion at bare surfaces, corrosion at reaction product covered surfaces, corrosion inhibition, and localized corrosion. Each general state of knowledge about the area, and to suggest possible fruitful areas for study. A final section summarizes the potential research areas.

ISSN:0094-243X    

DOI:10.1063/1.30800

出版商:AIP    

年代:1976

数据来源: AIP