ZINC By JASON GOMEZ Essays - Zinc, Group 12 Element, Brass

ZINC by JASON GOMEZ Zinc is a chemical element with the symbol Zn. It is a low-melting metal that belongs to Group IIb (zinc group) of the periodic table. The atomic number of zinc is 30. With an atomic weight of 65.39, zinc makes up an average of 65 grams of every ton of Earth's crust, which makes it a little more abundant than copper. The melting point of zinc is 420 degrees Celsius and its boiling point is 907 degrees Celsius (Britannica Online). Zinc is the second most common trace metal, after iron, that is found naturally in the human body. It is also the third most used nonferrous metal (after aluminum and copper), of which the U.S. consumes more than one million metric tons annually (American Zinc Association). According to the U.S. Bureau of Mines, the average person will use 730 pounds of zinc in his or her lifetime. Metallic zinc appeared much later in history than the other common metals. The Ancient Egyptians were the first to use zinc although they did so unintentionally! They made their brass from copper ores that were contaminated with zinc (Knapp, 4). There is some evidence that the Greeks knew of zinc's existence. They called it pseudargyras, or false silver, but they had no method of producing it in quantity. The Romans produced considerable quantities of brass, an alloy of zinc and copper, as early as 200 B.C. The metallurgists of India seem to have isolated the individual metal as early as the 13th century; and by the 16th century, China had achieved large-scale production. In the West, commercial zinc production got under way by the middle of the 18th century in England under the leadership of William Champion (Britannica Online). The first complete study of zinc was published in 1746 by Sigismund Marggraf, a German chemist (World Book). Canada is the leading producer of zinc followed by Australia, China, Peru, the U.S. and Mexico. In the U.S., mine production comes mostly from Alaska, Tennessee, New York, and Missouri (World Almanac, 151). There are 47 tons of zinc in one cubic mile of seawater. Zinc deposits occur in two quite different ways: first, as hydrothermal or contact metamorphic deposits, and second, as sedimentary deposits. Zinc was used as a component of brass until the 18th century. More than 50% of production is consumed in the preparation of alloys for die-cast products, and in anticorrosion treatment of iron and steel (Skinner, 19). A large share of the zinc produced today is used for galvanizing iron and steel (that is, coating them with zinc to make them rustproof). For many purposes, zinc is simply flattened into sheets called rolled zinc. These sheets are used in the manufacture of many roofing products, refrigerator linings, and printing plates. The compounds of zinc have numerous uses. Because of its high heat conductivity, zinc oxide is used in rubber as a heat dissipater. It is also used in the making of cosmetics, plastics, skin ointments, and soaps. Zinc sulfate is used in weed killers. Zinc sulfide has been used in X-ray screens and in luminous dials for clocks and watches (Compton's Encyclopedia). Zinc is also used in electric batteries and is required for the normal growth and healing of plants and animals. Zinc can also be combined with other metals to form many other alloys (mixtures). For example, brass is an alloy of copper and zinc. Bronze is copper, tin, and zinc. And nickel silver is copper, nickel, and zinc (World Book). The following statistics are stated in the U.S. Geological survey, U.S. Dept. of the Interior. As of mid-1996, the world mineral reserve for zinc was 330 million metric tons. U.S. Zinc Production, 1950-95 (in thousand metric tons) 1950 565,516 1989 275,883 1960 395,013 1990 515,355 1965 554,429 1991 517,804 1970 484,560 1992 523,440 1975 425,792 1993 488,283 1980 317,103 1994 570,162 1985 226,545 1995 601,000 In 1950 the total production of zinc was 565,515 thousand metric meters. The estimated total reserves for 1950 was 85,000,000 metric tons, but that was before the enormous amount of native zinc was discovered in Australia (Skinner, 62). In the year 2000, the projected total of zinc production is 550,000 thousand metric meters and the total world reserve will be at an estimated 320,500,000