MIME 413 & 513 – Mine Planning Optimization under Uncertainty – Fall 2014 Lecturer: R. Dimitrakopoulos
Whittle Parameter File The Whittle parameter file contains the following general information, for further details please consult Whittle’s help documents (can be accessed within the software). It is important to note that although the information below is a list of what may be contained in a parameter file, the inclusion of all the above parameters is not required for it to serve its purpose. Dimensions of a block are the X, Y and Z directions, respectively. Origin coordinates related to the origin of the model framework is at the outer corner of the block with coordinates 1,1,1. Dimensions of the model framework are expressed as the number of blocks in the X, Y and Z directions, respectively. General formatting requirements provide the number of decimal places to be used for the input and output of various quantities, other than those associated with specific elements. Active blocks indicator specifies which blocks you want Whittle to work on when doing the optimizations. There are three possible indicators, and are defined as follows: o Active blocks indicator of 1: all of the blocks in the model framework are considered for mining. o Active blocks indicator of 2: only the blocks within sub-regions are considered for mining. The sub-regions do not need to fill the model framework. If blocks occur in the Model File in regions not included in a sub-region, they are rejected. An active blocks indicator of 2 can be useful in certain unusual circumstances. o Active blocks indicator of 3: only blocks provided in the Model File are considered during optimization. That is, the rest of the blocks in the model framework are completely ignored. Restart interval lets you specify the time between dumps. Dumps refer to the Pit Shells node which periodically dumps all of the data from memory to its Work File to enable a later restart. This can be extremely helpful if, for example, a long optimization run is terminated because of power failure. If the restart interval is left blank, restart dumps occur every two hours. Reference mining cost is the cost of mining waste of undefined rock-type at the Reference Block. Cost of mining waste of a defined rock-type at the Reference Block is obtained by multiplying the Reference Mining Cost by the appropriate rock-type mining CAF (cost adjustment factor). Cost of mining waste of any type at a particular block is obtained by multiplying the cost of mining the same rock as waste at the Reference Block by the positional mining CAF for the block in question. Mining dilution factor - Example: A five percent dilution would be effected by a mining dilution factor of 1.05. The dilution is applied by increasing the tonnage of mineralized parcels, regardless of whether there is any waste (non-parcel tonnage or parcels with no
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MIME 413 & 513 – Mine Planning Optimization under Uncertainty – Fall 2014 Lecturer: R. Dimitrakopoulos
elements) in the block. This can lead to a negative waste tonnage for an individual block and, in regions of the pit that are entirely mineralized, negative stripping ratios are possible. Mining recovery factor is applied to take into consideration the loss of ore due to mining at the edge of the orebody or during transportation to the mineral processing plant. The mining recovery factor allows an overall mining recovery to be applied. General default block tonnage is used by the Reblocked Block Model node and by the Pit Shells node (where the active blocks indicator is set to 1 or 2) for blocks that are not specified in the Model File. Default block tonnages can be blank (meaning undefined), or a value that is zero (to represent air), or positive. Ore selection method flag controls how Whittle selects ore for processing from the available parcels. There are two possible flag settings: 1 and 2. o Ore selection method flag set to 1 – Selection by cut-off
Ore is selected by comparing the grades of the material with precalculated processing cut-offs. If the material does not satisfy the cut-offs, it is treated as waste.
If more than one processing method is applicable, the grades are compared with the cut-offs of each in turn, in the order in which they are specified in the Parameters File.
o Ore selection method flag set to 2 – Selection by cash flow
Ore is selected by comparing the cash flow that would be produced by processing it, and the cash flow that would be produced by mining it as waste. If the cash flow from processing it is higher, the material is treated as ore. If not, it is treated as waste. If more than one processing method is applicable, the one that produces the highest cash flow is used.
Air flags are used to specify the treatment of air blocks or undefined blocks in the model: o Air flag A controls whether air blocks are included or excluded, during pit optimization. There are two possible flag settings: 1 (included) and 2 (not included). o Air flag B controls which air blocks from the Model File are included in the Results File. There are three possible flag settings: 1, 2 and 3. o Air flag B set to 1: air blocks are not included in the Results File, regardless of whether air blocks were included or excluded during optimization. o Air flag B set to 2: only those air blocks are included in the Results File that would be "mined" as part of the largest pit extended into the air. The positional mining CAF flag controls whether or not the positional mining CAFs are used by the Pit Shells node and the Analysis nodes (Analysis program). There are two possible flag settings: 1 and 0. Positional mining CAF flag set to 1: the positional mining CAFs in the Model File are used by the Pit Shells node and the Analysis nodes.
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MIME 413 & 513 – Mine Planning Optimization under Uncertainty – Fall 2014 Lecturer: R. Dimitrakopoulos
Positional mining CAF flag set to 0: the positional mining CAFs in the Model File are not used by the Pit Shells node nor are the Analysis nodes. The positional processing CAF flag controls whether or not the positional processing CAFs are used by the Pit Shells node and the Analysis nodes. There are two possible flag settings: 1 and 0. Positional processing CAF flag set to 1: positional processing CAFs in the Model File are used by the Pit Shells node and the Analysis nodes. Positional processing CAF flag set to 0: positional processing CAFs in the Model File are not used by the Pit Shells node nor the Analysis nodes. The print unprocessed mineralisation flag controls whether or not the Pit Shells node and the Analysis nodes report the total tonnage and element content of any mineralised material that is mined but not processed. These quantities can be useful when reconciling the results of different runs. There are two possible flag settings: 1 and 0. Revenue Factor values in the pit shells node are used to scale base case prices up or down, in order to control which nested pits are to be produced. Regarding Sub Regions; Parameter Files with no sub-regions are valid, but then the Slope Set node will demand an Additional Arcs File, which will have to contain all of the required arcs. Block limits specifies the size and location of a sub-region by its lowest and highest block numbers in the X, Y and Z directions. Sub-region default block tonnage Default block tonnages are used by the Reblocked Block Model node and by the Pit Shells node (where the active blocks indicator is set to 1 or 2) for blocks that are not specified in the Model File. If the density of rock varies within the model framework, but the variation can be simulated by allocating different default block tonnages to different sub-regions, then sub-region default block tonnages can be useful. Slope angle should be provided along with information of the bearing and the slope. Bearings are expressed in degrees, clockwise from the positive Y direction – usually north. It is very important to note that bearings are given instead of wall positions. Any walls at right angles to the bearings, in a particular slope region, will have the given slope applied. Slopes are expressed in degrees from horizontal. Number of benches to consider for arc generation may control the accuracy of slope reproduction. The more benches that you specify, the greater the accuracy, and the longer the optimization will take. Grade dependent expression information must include an expression identification code, the expression usage and the definition of the expression. The element type code is an alphanumeric code of from 1 to 4 characters which identifies a particular element in the model. It is not case sensitive. Examples: GOLD, Cu. The position in the Model File specifies the position of the element data.
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MIME 413 & 513 – Mine Planning Optimization under Uncertainty – Fall 2014 Lecturer: R. Dimitrakopoulos
The element formatting requirements provide the number of decimal places to be used for the input and output of element quantities in a parcel, total quantities and grades. The selling cost per unit is the cost involved in selling a unit of the element, where a unit is defined by the values used for quantities of the element in the Model File. The price per unit is the price for a unit of the element where a unit is defined by the values used for quantities of the element in the Model File. It is used with the Revenue Factors to determine element prices for different pit shells. Rock-type information must include the rock-type code, the rock-type mining CAF, the rehabilitation cost per tonne and the processing throughput factor. The rock-type code is an alphanumeric code of from 1 to 4 characters which identifies a particular rock-type in the model. It is not case sensitive. Examples: OXID, SULF, WTHR. The rock-type mining CAF is the ratio between the cost of mining this type of rock as waste, and the cost of mining undefined blocks. The rehabilitation cost is the cost associated with rehabilitating waste dumps chemically, visually and ecologically. This cost is applied if the material is treated as waste, but not if it is processed. Processing-method/rock-type for open pit mining must include processing method code, rock-type code, processing cost and element information. The processing method code is an alphanumeric code of from one to four characters. It identifies the processing method to be used. It is not case sensitive. Examples: MILL, HEAP, CIL. The rock-type code, which is not case sensitive, must be one of the codes defined for a rock-type. The pairing of the method and type codes indicates that parcels of this rocktype may be processed by this processing method, if it is economic to do so. If a rocktype, even one containing elements, occurs in the Model File, but is not paired with a processing method here, it will be treated as waste. Processing cost the effective processing cost is used for calculating cash flows as well cut-offs. Element type code must be one of the codes defined for an element above. Cut-off control flag dictates whether or not the element(s) are cut-off controlled. This is only relevant when ore selection is by cut-off. Element processing cost per unit is the cost that can be calculated based on the units of each element input into the process, where a unit is defined by the values used for quantities of the element in the Model File. It is in addition to the general processing costs. Processing recovery fraction is the processing recovery (e.g. 0.93) at high grade for this element. Processing recovery threshold is a grade that is subtracted from the actual grade of each parcel before the processing recovery fraction is applied.
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