1、英文翻译原文PUMP AND CYCLONE DESIGN/OPTIMIZATION TO MAXIMIZE GRINDING CIRCUIT EFFICIENCYR. E. McIvor, Metcom Technologies, Inc., Marquette, MIABSTRACT :The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined sp
2、ecifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will de
3、liver those performances can be carried out. The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, “Circuit Classification System Efficiency” (CSE), is the fraction of “coarse” material inside the ball mill upon which grindin
4、g energy is deliberately expended, versus the remaining fraction of “fines” or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable, tar
5、get CSE for any given circuit can be estimated, for example by referring to a plant data base of CSEs. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE. This paper outlines the step-by-step, systematic method of pump and cyclo
6、ne selection which maximizes CSE. Numerous examples of its successful application are provided.THE FUNCTIONAL PERFORMANCE EQUATIONObservation of the feed and product size distributions going into and discharging from the mill in grinding circuits with low versus high circulating load ratios initiall
7、y led to the definition of “Circuit Classification System Efficiency” (or CSE, McIvor, 1988a), and subsequently the discovery of the Functional Performance Equation (McIvor, 1988b, and McIvor et al, 1992). The CSE is the fraction or percentage of “coarse” (usually in reference to the plus P80) size
8、material inside the mill, versus “fines” or product size material finer than the circuit P80. It can be readily calculated by taking the average of the percentage of said coarse material in the mill feed and mill discharge streams. As this also represents the percentage of the mill energy expended o
9、n targeted, coarse size material, it is directly proportional to overall grinding circuit efficiency and production rate. This is all clearly expressed in the Functional Performance Equation for ball milling circuits, for which the derivation has often been presented (e.g. McIvor, 2006).Circuit Prod
10、uction Rate=Total Mill PowerxCSExMill GrindingEfficiencyxMaterial Grindability of New Fine Product FACTORS AFFECTING CIRCUIT CLASSIFICATION SYSTEM EFFICIENCY Setting “Mill Grinding Efficiency” aside for this discussion, to optimize circuit performance we must maximize CSE within economic constraints
11、. This is achieved through the pump and cyclones (or other classifiers). The factors which collectively affect CSE have been presented elsewhere (McIvor, 2009), and are summarized as follows.For the circuit shown in Figure 1, the factors which we can manipulate to maximize CSE are the following.Figu
12、re 1. Typical Ball Mill Circuit.(1) The circulating load ratio: See Figure 2 (Davis, 1925 and Gaudin, 1939). Circuit efficiency increases with circulating load ratio, drastically so at the lower values. The increase in circuit production rate vs. circulating load ratio has been shown be a direct, li
13、near effect of increasing CSE.2Figure 2. Circuit Production Rate vs. Circulating Load (Davis, 1925; Gaudin, 1939).(2) Classifier basic (reduced) separation performance: The reduced cut size (d50c) is determined by the cyclone physical dimensions and feed slurry characteristics (for example, see Heis
14、kanen, 1993). The d50c is also the key determinant to select the cyclone(s) and pump needed to achieve the desired circulating load ratio. The finer the cut size, the greater the proportion of classifier feed reporting to oversize (underflow), and thus, by definition, the higher the circulating load
15、 ratio. The sharpness of separation is likewise influenced by the cyclone physical design (for example, new models like “Cavex” and “Gmax” provide sharper separation performance than their predecessors) and the feed slurry characteristics, in particular percent solids (again, see Heiskanen, 1993). T
16、he sharper the reduced classification, as measured, for example, by Plitts (1971) m, the fewer will be the fines reporting to the coarse product stream (and going on to the mill). As well, newer cyclone designs with better separation performance also require lower feed pressure for the same flow rates.(3) Water balance at the classifier: The portion of the cyclone feed water which reports to the oversize stream (the cyclone underflow) is
