The shaded figures represent ideal conditions for right angle bending. Tonnagecutoff model and average gradecutoff model for a single ore deposit qingfei wanga,b, jun denga,b. The mine call factor mcf is generally expressed as the gold called for versus the gold accounted for. Forecasting the gradetonnage curves and their uncertainty at. Database and grade and tonnage models, 2008 by donald a. You can click the add button under curves to add more grade tonnage curves to the graph. The relationships between grades and tonnages are analyzed by examining the correlation coefficients of these variables. Three types of copper depositsporphyry, stratabound, and massive sulfideare described, and the distributions of tonnages and grades for 267 deposits are compared with normal and lognormal frequency distributions. Including a ni grade increase in comparison to the previous estimate from 1. The grade tonnage curve for the fresh zone is shown in figure 3 below. You will be asked to provide a file name and storage location for the new pdf file. Grading on a curve austin community college district. As infill drilling is added, the shape of the gradetonnage curve changes.
These cumulative curves were then validated against 70 years of historical world average ore grade using production input by ore type from 1800 to 2000. Geostatistical simulation technologies1 provide an increasingly recognized tool to model geological uncertainty and quantify. Independent report on the nickel laterite resource agata north, philippines 20 2 in comparison to the august 2010 resource there is an increase of 4. Figure 1 grade tonnage curve for the niobium mineral. Other factors that must be taken into account in the calculation of cutoff grades but may not be quantifiable are represented by uothx. Highgrade goulamina lithium deposit resource expansion. Capital investment in mining projects requires the quantification, understanding and assessment of risk in gradetonnage curves. Gradetonnage curves, orewaste selection and planning. Tonnage cutoff model and average grade cutoff model for a single ore deposit qingfei wanga,b, jun denga,b. Assessment of uncertainty in gradetonnage curves of a multivariate lateritic bauxite deposit through minmax autocorrelation factor transformation. A guide to selecting the optimal method of resource estimation for multivariate iron ore deposits c devitry1, j vann2 and h arvidson3 abstract when only widespaced drilling is available, for example at concept, prefeasibility and feasibility stages, properly implemented linear estimation including ordinary kriging predicts grade tonnage. For the fresh zone the following relationship is seen from the gradetonnage curve. Cutoff grade determination for the maximum value of a.
In this case a curve breaker can limit the professors ability to apply a curve. Locomotive tractive effort and power calculations tractive effort calculations. Improving the economics of lowgrade projects srk consulting. Creation of customised reports including grade tonnage curves. As the criteria for ore classification becomes more selective, the tonnage above the cutoff grade of the deposit decreases. For this purpose, in a first step, a set of simulated images of the orebody provide the grade tonnage curve and an uncertainty. Fractal model of gold concentrations in the channel samples in the ten selected drillholes. Because of the resistance produced by curves, they pose an added difficulty when located on grades. Locomotive power calculations greenville, south carolina. The grade tonnage curves display the tonnage above the cutoff grade and average grade of a deposit relative to cutoff grade. Forecasting the gradetonnage curves and their uncertainty. For this purpose, in a first step, a set of simulated images of the orebody.
To keep the combined resistance of grade and curve from overwhelming trains, grades are often compensated by being reduced on curves so resistance remains constant. A common variation of grading on a curve is to use a variety of different methods to adjust the test grade in some way. If the highest grade is a 97%, then a 3point curve is all that is allowed, even if the mean is 60%. As many professors establish the curve to target a course average of a c, citation needed the corresponding grade point average equivalent would be a 2. Selection and gradetonnage relationships springerlink.
As the cutoff grade increases, the average grade of the deposit also increases as. Table 3 the complete cutoff policy for base case using grade tonnage curve. In order to avoid serious errors in calculating a gradetonnage curve, we must be able to define clearly the relationships existing between estimates and the corresponding true values. The gradetonnage curve for updated inferred resources at west zone is shown in figure 4. Grade nb205 06 tonnage curve mrima orebody inferred resources no cutoff applied cutoff. At a cutoff grade of 2% tgc the deposit will have a balance of 20. How to curve an exam and assign grades david richeson. In practice, blocks are selected according to their estimated value and not according to their true unknown value. Assessing risk in gradetonnage curves in a complex copper. Pdf assessment of uncertainty in gradetonnage curves of.
It is shown that this constitutes an improvement over the prediction of the grade tonnage curves obtained via standard sequential gaussian simulation and median indicator. Forecasting grade tonnage curves at the mehdiabad deposit boll. Improvements in grade tonnage curve prediction via. First, a force of 2 to 5 pounds per ton of train weight is. The gradetonnage curve for the fresh zone is shown in figure 3 below. The distributions and relationships of grade and tonnage among some nickel deposits by m. Provide a name for the grade tonnage graph in the windows toolbar. An application of sequential gaussian fractal conditional simulation is presented, using actual sparse, irregularly spaced open cut gold data, to predict the grade tonnage curve associated with a single mining bench. Tonnagecutoff model and average gradecutoff model for a. Most of the time, this type of grading boosts the students grade by moving his or her actual percentage up a few notches or boosting the letter grade. Forecasting gradetonnage curves at the mehdiabad deposit boll. The results of carrying out this method through a complete orebody of a large tonnage seem to justify the labor involved thereinthe tonnage checks with the standard method to within 1. Forecasting the gradetonnage curves and their uncertainty at the mehdiabad deposityazd, central iran.
Ni 43101 technical report dasa uranium project mineral resource update, central niger for global atomic corporation csa global report. Conversely, as the cutoff grade is lowered, the tonnage of the deposit increases. Mineral deposit grade and tonnage models and numbersof undiscovered deposits. Sedimenthosted gold deposits of the worlddatabase and. Therefore, the metal tonnagecutoff curve and tonnageaverage grade curve are achieved, as shown in fig.
Most of the time, grading on a curve boosts the students grades by moving their actual scores up. In many cases, the ratio calculated is between the average grade in grams of gold per tonne of ore. Goulamina a large tonnage high grade lithium deposit the updated resource estimate at goulamina confirms a highgrade and bulk tonnage lithium deposit. The tonnagegrade curve provides two key characteristics for the deposit under investigation. Mineral deposits vary widely in terms of their physical continuity and homogeneity of grade distribution.
Figure 1 grade tonnage curve for the niobium mineral resource estimate mrima hill deposit figure 2 surface plan view of resource model showing continuity of high grade zone. Figure 5 gradetonnage tables and graphs for indicated and inferred resources this shows conceptual gradetonnage relationships only and is derived from inferred and indicated resources for which economic viability of realising tonnage above any given grade cutoff has not been assessed at this time. Grade and tonnage relationships among copper deposits. For the fresh zone the following relationship is seen from the grade tonnage curve. In order to avoid serious errors in calculating a gradetonnage curve, we must be able to define clearly the relationships existing between estimates and the. As the criteria for ore classification becomes more selective, the tonnage above. The distributions and relationships of grade and tonnage. Change of support maps this and allows the resource geologist to identify the potential gradetonnage curve at the time of mining grade control drilling.
This new grade and tonnage model is remarkable in that the estimated parameters of the resulting grade and tonnage distributions are comparable to the previous model of mosier and others 1992. Posted by dave richeson on december 22, 2008 march 23, 2011. Both tonnage and grade of sulfide deposits associated with komatiitic rocks follow lognormal distributions. Pulp densities indicate by means of a tabulation the percentages of solids or liquidtosolid ratio in a sample of pulp. Assessing risk in gradetonnage curves geostatistical association. Leapfrog geo can display multiple grade tonnage curves on one graph. From the gradetonnage curve, the relationship between the volume tons available for mining and the cutoff grade as well as the resultant average grade above the cutoff grade can be determined. This figure is valuable in two waysdirectly, because for each unit process and operation in milling the optimum pulp density must be established and maintained, and indirectly, because certain important tonnage calculations are based on pulp density. Chapter 11 gradetonnage curves, orewaste selection and planning problems. The approach used for this study is to select various cutoff grades and use the financial optimization model to determine which combination of tons. Usually, the more variable the grades are the more complex the geometry is and the less reliable the curve is silva and soares, 2002. The export button in the windows toolbar saves the current grade tonnage graph as a pdf file. A grade tonnage curve combines two or three equations together to produce one of the more important tools for analysing the data indicating the potential amount of material obtained when varying the cutoff grade applied.
A notable change is in the reporting of silver in more than 10 percent of deposits. Revisiting the cumulative gradetonnage relationship for. Dynamic visualisation of single or multiple planes through advanced reserve reporting with ability to break down by support for a large number of blocks with. We have tried t o s h o w that in fact there are more fundamental questions and that a gradetonnage curve. Singer and others published grade and tonnage models find, read and cite all the research you need on.
Understanding cutoff grade 4 tonnage, grade, and costs. The model was used to create cumulative gradetonnage curves, representing 1,778 million metric tons mt of mineable copper. The distributions and relationships of grade and tonnage among. A guide to selecting the optimal method of resource. Assessing risk in gradetonnage curves in a complex copper deposit 373 introduction capital investment in mining projects requires the quantification, understanding and assessment of risk in gradetonnage curves. Grading on a curve is a term that describes a variety of different methods that a teacher uses to adjust the scores her students received on a test in some way. The tractive effort required to move a train consists of numerous factors, but for most applications only four need to be considered. Gradetonnage curves are a visual representation of the impact of cutoff grades on mineral reserves.
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