tailieunhanh - Encyclopedia of Global Resources part 48

Encyclopedia of Global Resources part 48 provides a wide variety of perspectives on both traditional and more recent views of Earth's resources. It serves as a bridge connecting the domains of resource exploitation, environmentalism, geology, and biology, and it explains their interrelationships in terms that students and other nonspecialists can understand. The articles in this set are extremely diverse, with articles covering soil, fisheries, forests, aluminum, the Industrial Revolution, the . Department of the Interior, the hydrologic cycle, glass, and placer mineral deposits. . | 418 Feldspars Global Resources Feldspar World Mine Production 2008 Argentina Brazil China Colombia Czech Republic Egypt France Germany India Iran Italy Japan Malaysia Mexico Poland Portugal South Korea Spain Thailand Turkey United States Venezuela Other countries Million Metric Tons Source Data from the . Geological Survey Mineral Commodity Summaries 2009. . Government Printing Office 2009. Global Resources Feldspars 419 icut to grind feldspar for the newly developed pottery industry in the United States. The largest production of feldspar in the United States is in North Carolina followed by Virginia California Oklahoma Georgia Idaho and South Dakota. Crude feldspar is also produced by at least thirty-eight other countries. China Turkey Italy and Thailand jointly produce approximately 60 percent of the world s total feldspar. . production of crude feldspar is about 3 percent of the world total. Obtaining Feldspar The method used to obtain feldspar depends on the type of deposit to be mined. Most feldspar can be quarried by open-pit mining. Some feldspars are mined by boring down through distinct zones within pegmatite dikes but many deposits require the use of explosives and drills. Dragline excavators are used to mine feldspathic sands. High-grade feldspar can be dr y-processed. It is sent through jaw crushers rolls and oiled pebble mills and is finally subjected to high-intensity magnetic or electrostatic treatments that reduce the iron content to acceptable levels. Feldspathic sands are crushed and rolled then processed by a three-step froth flotation sequence . End Uses of Feldspar Source Data from the . Geological Survey Mineral Commodity Summaries 2009. . Government Printing Office 2009. that removes mica extracts the iron-bearing minerals and finally separates the quartz residuals. Sometimes the last flotation procedure is omitted so that a feldspar-quartz mixture can be sold to the glassmaking industr y. The feldspar is ground to about .