698 



UNITED STATES MINERAL RESOURCES 



haps semitropical laterites, both modem and ancient, offers 

 considerable promise for the discovery of significant high- 

 grade tonnages of shallow nonsulfide ores that can be worked 

 by large-scale open-pit methods. Such ores are of interest 

 also because they do not contribute to sulfur emission prob- 

 lems during reduction. 



INTRODUCTION 



Zinc is necessary to modern living and, in tonnage 

 produced, stands fourth among all metals in world 

 production — being exceeded only by iron, aluminum, 

 and copper. Elemental zinc is a bluish-white metal 

 when freshly cast and has a specific gravity of 7.13. 

 Its melting and boiling points are 419°C and 906°C, 

 respectively. It alloys readily with other metals and 

 is chemically active as well. On exposure to air it 

 develops a thin protective impervious gray oxide 

 film, an important characteristic in its use. Most 

 commercial zinc is produced in the metallic form 

 called slab zinc and comes from the smelter in 

 various sizes and shapes. Some zinc concentrates 

 are converted directly to zinc oxide for use as such. 

 Primary slab zinc is prepared in several grades 

 depending on impurities, ranging from Prime West- 

 ern with a minimum zinc content of 98.0 percent to 

 Special High Grade with a minimum zinc content of 

 99.99 percent. The impurities are chiefly lead, iron, 

 and cadmium ; trace quantities of copper, tin, and 

 aluminum may also be present. 



Zinc is utilized chiefly in the automobile, house- 

 hold appliance, and hardware industries. The metal 

 has three major uses: (1) for zinc-base alloy die 

 castings, (2) for galvanizing iron and steel prod- 

 ucts, and (3) in the manufacture of the copper-zinc 

 alloy, brass. In the United States, these three uses 

 account for about 90 percent of the total consump- 

 tion. Other important uses are as rolled zinc metal 

 and in the preparation of zinc compounds for the 

 manufacture of a variety of industrial products — 

 for example, zinc oxide in rubber and in paints. 

 (See tables 149-151.) Possible substitutes for zinc 

 in die casting are magnesium and aluminum, par- 

 ticularly if a weight limitation is important. Plas- 

 tics are also competing in the die-casting field as 

 metal-on-plastic plating techniques are being per- 

 fected. Aluminum is being substituted for galvanized 

 sheet steel in the light-construction industry, but 

 there appears to be no satisfactory altei'nate to zinc 



Table 149. — Consumption of zinc, in short tons, in the United 

 States, 1969 



Slab zinc 1,368,323 



Ores (recoverable zinc content) 126,712 



Secondary (recoverable zinc content)' 302,075 



Total 1,797,110 



1 Excludes redistilled slab and remelt zinc. From Moulds, (1969, p. 1159, 

 table 15). 



for the large tonnages used for the corrosion pro- 

 tection of the wide variety of iron and steel products 

 needed by modern civilization. Heindl (1970) gave 

 additional information on the uses of zinc and its 

 place in industry. 



Table 150. — Slab zinc consumption, in short tons, in the 

 United States, by industry uses 

 [NA. not available] 

 Industry and product 1966 1969 



Galvanizing: 



Sheet and strip 270,826 251,625 



Wire and wire rope 43,884 32,348 



Tubes and pipes 63,224 65,898 



Fittings (for tubes and pipes) 8,641 11,418 



Tanks and containers NA 5,561 



Structural shapes NA 19,454 



Fasteners NA 5,536 



Pole-line hardware NA 9,409 



Fencing, wire cloth, and 



netting NA 17,984 



Job galvanizing 51,011 NA 



Other and unspecified uses 44,835 57,091 



Total 482,421 476,324 



Brass products: 



Sheet, strip, and plate 58,864 90,777 



Rod and wire 45,510 56,989 



Tube 10,030 10,928 



Castings and billets 3,050 5,958 



Copper-base ingots 7,402 13,642 



Other copper-base products __ 1,992 1,175 



Total 126,848 179,469 



Zinc-base alloy: 



Diecasting alloy 629,809 565,839 



Dies and rod alloy 535 504 



Slush and sand casting alloy __ 7,626 10,048 



Total 637,970 576,391 



Rolled zinc 45,882 48,650 



Zinc oxide 25,781 41,447 



Other uses: 



Wet batteries 1,188 1,536 



Desilverizing lead 2,444 3,957 



Light-metal alloys 8,124 7,562 



Other' 23,434 32,987 



Total - 35,190 46,042 



Grand total 1,354,092 1,868,323 



^ Includes zinc used in making zinc dust, bronze powder, alloys, chemi- 

 cals, castings, and miscellaneous uses not elsewhere mentioned. From 

 Moulds (1969. p. 1160, table 16). 



Table 151. — Distribution of zinc oxide and leaded zinc oxide 

 shipTnents, in short tons, by industries 



[W, withheld to avoid disclosing individual company confidential data; 

 included with "Other." Data from Moulds (1969, p. 1162, table 22) ] 



Industry 1965 1969 



Zinc oxide: 



Rubber 103,057 115,988 



Paints 30,249 25,170 



Ceramics 10,009 9,469 



Chemicals 11,365 22,775 



Agriculture 977 4,007 



Photocopying W 27,566 



Floor covering 363 W 



Other 30,550 14,748 



Total 186,570 219,723 



Leaded zinc oxide: 



Paints 10,951 4,905 



Rubber ] 899 2,051 



Other and unspecified 1 __^ 



Total 11,850 6,956 



