12 and separ at ed b y qualit y Impurities in the c oal ar e r emo v ed b y v arious mechanical t echniques in cluding pulsating w at er curr ents r apidly spinning w at er and liquids of dif er ent densities In all cases metallur gists mechanical engineer s electricians w elder s and other skilled t echnicians ar e critical t o k eeping the oper ation of these pr oc es sing f acilities running smoothly See pag e 16 f or mor e inf orma tion on pr oc es sing 5 Restoration Once mining is complete at a site engineers metallurgists and environ mental specialists begin the r est or ation process returning the landscape to its natural form or to another acceptable use such as recreation wildlife habitat or economic development ar eas At large coal surface mines and some miner als mines recla mation often begins in the sections where the coal or minerals have already been removed even while mining is continuing elsewhere at the site W aste rock is treated and the t opogr aph y is carefully con tour ed Mined areas can be suc c es sfully converted to wetlands and other appr o v ed uses The earth is seeded with indigenous species and biologists and hydrogeologists monitor sites for years after min ing is c omplet ed to ensure environmental g oals are met PR ODUC TION and PREP ARA TION US GS Miner als C ommodit y Summaries Estimat ed Nonfuel Miner als V alues billion dollar s Y ear US P r oduction Mat erials P r oc es sed 20 12 76 5 70 4 20 1 3 74 2 6 65 201 4 7 7 6 6 97 201 5 7 8 3 6 3 0 201 6 74 6 6 75 201 7 7 5 2 7 27 201 8 82 2 76 6 Sinc e 19 77 US mining c ompanies ha v e r est or ed mor e than 3 million acr es of mined land and ha v e plant ed mor e than 500 million tr ees Miner al pr oduction is a cyclical business with production levels for any given period showing peaks and valleys for almost every mineral Production rates are determined by worldwide demand as much as by exploration success Of 2500 known minerals about 50 are major economic commodities that are commonly explored mined and traded internationally The United States produces 78 major mineral commodities more than any other nation involved in min ing These include antimony bauxit e beryllium borax boron clays coal copper diamonds diatomite feldspar gold gypsum iron ore lead limestone molybdenum perlite phosphate rock platinum and pal ladium pumice rare earth metals salt sand and gravel silver s odium sulfate stone trona and uranium By comparison Russia produces the next largest number of mineral commodities 60 followed by China 53 Canada 49 India 46 South Africa 44 Germany 44 and Australia 42