16 The preparation process is crucial in readying coal and minerals for the marketplace This step assures that the resource sent to the end user is of the highest possible quality In the case of coal there is also an environmental beneft physical coal cleaning can remove as much as 90 percent of the inorganic or pyritic sulfur that could otherwise contribute to emissions during the combustion process P reparation plant s crush and scr een c oal and emplo y a cir cuit of cleaning t echniques t o r e m ove noncoal materials and separa t e the c oal into dif f er ent qualit y grades And f or some minerals including structural mate rials lik e sand and gr a v el washing and separating for size is t ypically all that is involved F or metallic or es ho w e v er it is a dif er ent st ory The number and complexity of steps in processing these ores is often directly related to the complex ity of the ore itself and the degree of purity needed for the end product In or der t o separ at e the miner al fr om surr ounding or e the fr st st ep is t ypically t o tr anspor t the ore to a mill where the mineral is concentrated The process begins by crushing or grinding the o re to the degree of fneness needed to e xtr act the min er al mat erial c ontained within Then the mineral is physically separated by leaching using a perco lating liquid to remove soluble parts fotation or solvent extraction Flotation is a chemical and physical process in which the ground ore is mixed with water and a foaming agent The slurry is then agitated much as if in a washing machine and bubbles are cre ated T he mineral mat erial attaches t o the bubbles and foats to the top to be skimmed of This pro cess makes it possible to a cce s s low er grade min eral deposits that otherwise would not be utilized Solvent extractionelectrowinning SXEW is a process that is used in copper production The process uses electricity to extract the metal from a solvent solution and attach it t o a cathode SXEW has increased in use since the mid1980s partly because it can recover copper from low er gr ade ores that otherwise c ould not be processed For both coal and minerals the processing step is referred to as benefciation the processing of coal and ores to regulate size remove impurities and improve quality Some minerals undergo further refnemen t sometimes by a smelting process to obtain the desired degree of purity Once this level of purity has been achie v ed the mineral is ready for commercial use whether gold for electronics and jewelry c opper for plumbing or electrical wire or one of many other potential end uses US P er Capita C onsumption of Miner als and C oal 20 18 Miner al P ounds C ement 67 5 Cl ays 155 C oal 4 206 C opper 12 Ir on Or e 256 L ead 12 Phosphat e R ock 1 82 Salt 384 Sand and Gr a v el 7 345 St one 9 9 24 Zinc 6 Mang anese 6 Ur anium 2014 0 1 5 NMA calculations based on pr eliminary US GS EIA and US C ensus Bur eau data PR ODUC TION and PREP ARA TION P r epar ation