To achieve this purpose, a total number of 186 fullscale SAG mill works were investigated and the most effective parameters on SAG mill power,, feed moisture, mass flowrate, mill load cell weight, SAG mill solid percentage, inlet and outlet water to the SAG mill and work index were measured and utilized to develop the GEP model.
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was surprising that the Bond Rod Mill Wi average was kWh/t. Since the ore is unusually soft, the Rod Mill Wi is probably irrelevant in determining required power for the SAG mill. Drop Weight Tests Drop Weight tests were done at Hazen and analyzed by Contract Support Services, Inc. Table 4: Summary of 6 JKTech Drop Weight Tests
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A SAG mill is usually a primary or first stage grinder. SAG mills use a ball charge of 8 to 21%. The largest SAG mill is 42' () in diameter, powered by a 28 MW (38,000 HP) motor. A SAG mill with a 44' () diameter and a power of 35 MW (47,000 HP) has been designed. Attrition between grinding balls and ore particles causes grinding of ...
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SAG mills mimic the same shortcoming. It follows that in order to obtain the specifi c energy (SE) to achieve a certain transfer size, based on the 80 per cent passing value, an ineffi ciency factor must be applied to the SE of single stage ball mills, rod mills or AG/SAG mills when calculating power according to the Bond Third Theory method.
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• SAG Mill Design Test (Starkey, 2006). There are reasonable correlations between all the tests' data that generally allow any or all of the data to be used to design a SAG mill based grinding circuit for 'typical' ores of a moderate competence range. Issues have arisen where the expected SAG mill specific energy is greater than 10 kWh/t.
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where m p is in kW; D is internal mill diameter (meters), L is internal mill length (meters); J is total fractional charge loading of the mill; J B is the fractional mill filling by balls; ε B is the effective porosity of the charge, taken as ; ρ s and ρ b are true densities of rock and balls (tons per cubic meter), respectively; w c is the weight fraction of rock in water and rock in ...
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The correlation between the AG/SAG and ball mill circuit data is also very poor. Use of equation 2 shows a very different picture, the results being illustrated in Figure 7. This shows that on average the "M" operating work indices of AG/SAG and ball mill circuits are very similar and hence energy utilisation efficiencies are similar. Also
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SAG mill fractional total filling (J t) and ball filling (J b) are determined by solving the powerdraw or mill weight residuals given mill power draw or weight process measurements as inputs. SAG mill fractional rock charge filling (J r) is calculated by difference of the total and ball charge fractions, see Equation (11). J r J t J b (11)
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operation of SAG mills. SAG mills are currently the technology of choice in hard rock milling operations for reducing primarycrushed ore to ball mill feed. In recent years, the trend has been towards largersized SAG mills with diameters of m (34 ft) and above, with the largest being m (40 ft) in
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There are interactions between SAG mill operating parameters (bearing pressure, mill load weight, power draw and motor torque). The characteristics of the ore cannot be measured online and this will make MPC approaches difficult to calibrate. These characteristics includes: feed size distribution, hardness, breakage properties, microcracks ...
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These factors often translate to a higher unit power input (kWh/t) than an SAG circuit milling the same ore. but at a higher power efficiency (often assessed by the operating work index OWi, which if used most objectively, should be corrected by one of a number of techniques for varying amounts of fines between the two milling operations).
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Mill Weight Power Top Size Figure 4: Feed Top Size vs. SAG Mill Performance 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 13:00 14:00 15:00 16:00 17:00 kW Top size (mm) Top Size Power Mill Weight Figure 5: Feed Top Size vs. AG Mill Performance This is not say that ag mill performance ...
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Semiautogenous (SAG) mills are widely used grinding equipment, but some ore with critical particle sizes cannot be effectively processed by SAG mills and turned into pebbles. This research aims to analyze and compare the properties of raw ore and pebbles from a zinc and tinbearing ore. The results show that the contents of sphalerite, cassiterite, biotite, antigorite, pyroxferroite ...
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SAG mill water flow rate SAG mill power vs. wear geometry maximizing kWhr/ton tons/hour in combination SAG mill liner changeout life/cycle vs. tons/kg consumed. Ball mill liner efficiency based on liner geometry and its influence on kWhours/ton, total tons/life cycle, and P80 transfer to cyclones. Ball mill grind is based on different ...
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The standard JK drop weight test breaks single particles at five size fractions each at different energy levels by dropping a given weight from a certain height. ... and in feed size distributions caused the SAG mill throughput to fluctuate between 700 and 3000 t/h ... (Ecs) and breakage intensity (t 10 %) is described as a powerlaw ...
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Methods to Estimate AG/SAG Mill Grinding Power Requirements. (1) Using the results of SMC data. (2) Using SAG Power Index (SPI) data. (3) Using the 1989 Barratt method updated on Alex Doll's Web site (February 16, 2015) (3) Using Don Burgess' method (11th Mill Operators Conference 2012) They seem to give very different predictions for ...
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(1) Jx is the mill filling of component x, L is the mill effective grinding length, m as a fraction of total mill volume ( for 30%) P is the power evolved at the mill shell, kW wC is the charge %solids, fraction by weight ( for 80%)
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With our SAG mill running at % critical speed (mill RPM), the SER motor speed reference is 850 RPM or 85% of 1000 RPM. We are recovering approximately MW of slip energy; the power ...
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To date, CITIC HIC has cumulatively produced and delivered over 1,550 mineral grinding mills, with a total installed power of 3,900MW. Our largesize grinding mills hold a market share of 85% in the domestic mining market, and have been exported to more than 50 countries and regions. This means that we are a world's leading manufacturer and ...
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Thus the power to drive the whole mill. = + = = 86 kW. From the published data, the measured power to the motor terminals is 103 kW, and so the power demand of 86 kW by the mill leads to a combined efficiency of motor and transmission of 83%, which is reasonable.
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