each alternative is calculated asStep 11: According to the closeness coefficient, determine the ranking order of all alternatives。 It is clear that The order of
all alternatives can be determined according to the descending order of 。3 Case study: Golegohar Iron Mine in Iran
The Goelgohar Iron Mine is located about 55 km southwest of Sirjan in the province of Kerman, Iran, between 55°11′50″E and 55°12′40″E longitudes and 29°13′0″N and 29°17′0″N latitudes。 This mine with an altitude of 1750 m above the sea level is situated at the center of a triangle comprising the cities of Kerman, Shiraz and Bandar Abbas。 The Golegohar deposit forms
in six separate anomalies at a confinement of about 10 km length and 4 km width。 The total ore reserve of the mine is approximately 1135 million ton。 This with metamorphic rocks of Paleozoic consists mostly of gneiss, micaschist, amphibolite, quartzschist, marble, dolomite and calcite types of rocks。 Anomaly No。 3 is the biggest anomaly at this mine。 On the basis of exploration work, the total ore reserves of anomaly No。 3 are calculated as 616 million tons with an average grade of 54。3% Fe。 Location of this mine is shown in Fig。 2。 Table 1 shows physical and mechanical characteristics of ore deposit of the third anomaly [21]。 Also, the results of determination of the granular composition in the dump of the Golegohar Iron Mine for various blasting patterns are given in Table 2 [22]。
4 Primary crushers
Typical primary crushers in open pit mining were gyratory, double toggle crusher, single toggle crusher, double-roll crusher, low speed sizer, impact crusher, hammer mill and feeder breaker。 These crushers were introduced as following。 In gyratory crusher, a conical shaped element is supported in a flared shell or frame creating a chamber wide at a top and narrow at the bottom。 The center element is caused to gyrate about its fulcrum point causing it to advance and retreat with relation to the shell。 Double toggle crusher consists of a stationary and a moving jaw so positioned as to provide a wide opening at the top and narrow at the bottom。 The movable jaw is fixed at the top and the motion is generated through the toggle arrangement。 The rock is squeezed with each motion of the moving jaw, broken and dropped by gravity to a lower position。 In single toggle jaw crusher, the motion is created by the eccentric shaft at the top of the jaw。 The maximum motion is at the top of the jaw。 The rock is squeezed with each motion of the moving jaw, broken and dropped by gravity to a lower position。 The double-roll crusher, a crushing device in which breakage occurs between a pair of rolls that rotate in opposite directions, is used for crushing particles into a size range of 1–50 mm。 The minerals of rock particles placed between the rolls are nipped and then crushed as they pass between the rolls。 Particles smaller than the gap between the rolls tend to pass through uncrushed, whereas those larger than the opening are nipped andcrushed。 The maximum size of particles that are nipped without slippage depends on the amount of friction, the distance between the rolls, and the diameter of the rolls。 The size of the product depends on the crusher set, i。e。, the distance between the rolls。 In low speed, sizer tows toothed rolls revolved in a chamber at low speed and high torque。 The teeth are so arranged that the crushing is accomplished by shear。 In impact crusher, one or two 模糊TOPSIS方法对初级破碎机英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_92562.html