Grinding mineral processing

L. G. Austin, K. R. WeUer, and I. L. Kim, "Phenomenological Modelling of the High Pressure Grinding RoUs," XTTII International Mineral Processing Congress, Sydney, AustraUa, May 1993, pp. 87—95. 

A. J. Lynch, Developments in Mineral Processing, Vol. 1, Crushing and Grinding Circuits Their Simulation, Optimisation, Design, and Control, Elsevier, Amsterdam, the Netherlands, 1977, 342 pp. 

The holdup of material in a continuous mill determines the mean residence time, and thus the extent of grinding. Gupta et al. [International J. Mineral Processing, 8, 345-358 (Oct. 1981)] analyzed published e)merimental data on a 40 X 40-cm grate discharge laboratoiy mill, ana determined that holdup was represented by = (4.020 — 0.176 WT)F , (0.040 0.01237 WT)S, - (4.970 0.395 Wl), where... 

FIG. 20 33 Effect of percent solids on the wear of mild steel halls, net weight of 325 mesh material produced, and pulp viscosity after grinding magnetic taconite for 60 min [Iwasaki et al.. International J. Mineral Processing, 22, 345A360 (1988).]... 

FIG. 20-35 Drais wet-grinding and dispersing system (U.S, patent 3,957,210) Draiswerke Gmbh, [Stehr, International J, Mineral Processing, 431—... 

Mular, A.L. and W. R. Bull, W.R. (Editors), Mineral Processes Their Analysis, Optimization and Control, Queens University, Ontario (1969) Mular, A. L. and N. A. lull, N.A., The Selection of Cyclone Classifiers, Pu ps and Pump Boxes for Grinding Circuits, Mineral Processing Plant Design , AIME, New York (1978)... 

Once the comminution process is completed, the succeeding operations in mineral processing are taken over by what is known as separation. Regardless of the method or methods used, the aim is always the same-to take a natural aggregate of minerals (an ore) and separate it into two or more mineral products. In general, the products of separation are (i) the concentrate which contains the valuable minerals and (ii) the tailings which contain primarily materials of little or no value. It may be borne in mind that minerals have been liberated, either by grinding or by chemical means, must usually be sized prior to... 

Separation processes, as could be seen from Figure 2.1, position themselves at the back end of the sequence in operations in the mineral processing flowsheet. The front-end operations has been found virtually to terminate with the liberation or the size-reduction processes involving crushing and grinding. It is important to limit the amount of size reduction to that at which adequate liberation is accomplished. The term adequacy is related to the cost involved in comminution and to performance of the concentration methods that follows. The concentration is obtained by separation processes which rely on differences in the properties of the particles, the physical and physico-chemical characteristics of minerals. In this context, it will only be relevant to refer to Table 2.5 which presents a summary of the processes along with the properties of the minerals that are exploited. 

Kitschen, L. P., Lloyd, P. J. D. and Hartmann, R. Proc. 14th ltd. Mineral Process. Congr. (Toronto, 1982) 1-9. 1. The centrifugal mill experience with a new grinding system and its application. 

Adam, K., Natarajan, K. A. and Iwasaki, I., 1984. Grinding media wear and its effect on the flotation of sulphide minerals. International Journal of Mineral Processing, 12(1 - 3) 39 - 54 Ahlberg. E. and Broo. A. E., 1988. Proc. Inter. Symp. Electrochem. In Mineral and Metal Process. 

Bulut, G. and Atak, S., 2002. Role of dixanthogen on pyrite flotation solubility, adsorption studies and E h. FTIR measurements. Minerals Metallurgical Processing, 19(2) 81-86 Cases, J. M., Kongolo, M., de Donato, P., Michot, L. and Eire, R., 1990. Interaction between firely ground galena and pyrite with potassium amylxanthate in relation to flotation, 2. Influence of grinding media at natural pH. Inter. J. Miner. Process, 30 35 - 67... 

Natarajan, K. A., Riemer, S. C., Iwasaki, I., 1984. Influence of pyrrhotite on the corrosive wear of grinding balls in magnetite ore grinding. Inter. J. Miner. Process, 13(1) 73-81 Nesbitt, H. W., Bancroft, G. M., Pratt, A. R., Scaini, M. J., 1998. Sulfur and iron surface states on fractured pyrite surfaces. American Mineralogist, 83 1067 - 1076 Neeraj, K. M., 2000. Kinetic studies of sulphide mineral oxidition and xanthate adsorption. Doctor thesis of Virginia Polytechnic Institute and State University. A Bell Howell Company UMI dissertation Services... 

Vathsala, K. A. Natarajan, 1989. Some electrochemical aspects of grinding media corrosion and sphalerite flotation. Inter. J. Miner. Process, 26(3 - 4) 193 - 203 Walker, G. W., Stout, J. V. Ill, Richardson, P. E., 1984. Electrochemical flotation of sulphides reaction of chalcopyrite in aqueous solution. Inter. J. Miner. Process, 12 55 - 72 Wang Dianzuo, 1983. Structure and reactivty of organic depressant on flotation. Nonferrous Metals, (2) 47-51... 

Wang, X., and Xie, Y., 1990. The effect of grinding media and environment on the surface properties and flotation behaviour of sulphide minerals. Miner. Process Extra Metall. Rev., 7 49 - 79... 

Yelloji Rao M. K. and Natarajan, K. A., 1989c. Effect of galvanic interaction between grinding media and minerals on sphalerite flotation. Inter. J. Miner. Process, 27(1 - 2) 95 - 109 Yelloji Rao M. K. and Natarajan, K. A., 1990. Effect of electrochemical interactions among sulphide minerals and grinding medium on the flotation of sphalerite and galena. Inter. J. Miner. Process, 29 175 - 194... 

D. Espig, V. Reinsch, Computer aided grinding circuit optimization utilizing a new mill efficiency curve, Int. J. Miner. Process. 44 15 (1996) 249-259. 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

Herbst et al. [International J. Mineral Processing, 22, 273-296 (1988)] describe the software modules in an optimum controller for a grinding circuit. The process model can be an empirical model as some authors have used. A phenomenological model can give more accurate predictions, and can be extrapolated, for example from pilot-to full-scale application, if scale-up rules are known. Normally the model is a variant of the population balance equations given in the previous section. 

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