''Global influence of metals''

Introduction

For this paper, we shall dwell and tailor the concept of metal in a holistic context. Metal production comprises approximately 7% of global energy use, making the sector one of the largest energy-consuming industries. Energy consumption is dominated by the production of iron and steel. An estimated 4% of world energy use is consumed in the production of iron and steel. Table I summarizes the estimated energy intensities for selected metals. The energy consumption data include the energy used in mining of the ores. It is important to note that there are relatively large differences in the energy intensity and efficiency of industrial processes in different countries and for plants within a country. Differences in energy use for metal production in various countries are due to differences in the raw material used (i.e., ore and scrap), the mix of products produced, material losses in the production process, and the energy efficiency of the production facilities.

These four factors also contribute to continuous changes in energy intensity. It has been estimated that the energy intensity in the U.S. iron and steel industry during the period 1980-1991 changed mainly due to improved energy and material efficiency and a change toward more recycling. However, in China, during the same period only energy efficiency improvement contributed to the change in energy intensity because it has less domestic scrap available. Good statistical information on energy use does not exist for all metal industries or countries.

TABLE I Energy Intensities of Primary and Secondary Metal Production*

Metal

Primary production (million metric tons)

Energy intensity, primary production (GJ/tonnc)

Energy intensity, secondary production (GJ/tonnc)

Energy savings of recycling (%)

* Values are approximate and will vary by product and production location. Energy intensity is expressed as primary energy. Electricity is converted to fuels used to generate the power.

Iron and steel

649

26

12

54

Aluminum

25.4

213

11

65

Copper

13.4

91

13-37

60-85

Table I provides estimates ...