Mining sequence is one of the key drivers for obtaining the objectives of a projects such as maximum NPV, achieving product blend, maintaining strip ratio or all of these and more.
Whether long term planning or medium term, the different sequence of mining in a schedule can vary the production, blend, strip ratio, cash flow and NPV largely. Hence it is essential to experiment on the effect of different sequence of mining in order to choose one that is aligned to the company and its objectives.
GEOVIA Minex provides a powerful yet simple tool to generate mining sequence files, which can then be used in a target scheduler.
In order to invoke the Minex sequence generator create a new schedule, display the pit reserves and select the menu : OP Schedule DB > Display > Sequence Generator
Type a file name. Select Strip Block offset and click Auto Generate. Next click on “Save File”. This will create a .dsq file which has a sequence of mining with the chosen strip offset and block offset.
The significance of strip and block offsets are explained in the image below. The image shows a one strip and four block offset. For a strip offset there will be an offset between of the number of strips before the subsequent bench is opened. For block offset there will be an offset of the number of blocks chosen between the advancing faces in adjacent strips.
In order to understand the sequence generated visually the replay option can be tried. To do so click on the Replay tab.
As shown above first browse for the sequence file created using the Browse button. Next click on “Load and Display Sequence File”. Make sure the reserves database has been displayed prior to that in a colour that you want. In the reserves database image above, it has been coloured by benches.
Next click the Play button and watch the sequence progressing on the screen. Once completed do not forget to press the Stop button. Any further operations done without pressing the stop button makes Minex susceptible to fail.
It is suggested to create multiple sequence files in this manner. The sequence files are editable text files. If the format is maintained, they can be manipulated in any text editor. Sequence files can be combined, edited etc. For those who want to try further – sequence files can be generated in csv format using excel as well.
Try to discover the effect of the following
Sequence generated for certain strips and blocks can be combined. Try to create a sequence that starts in the middle and progresses on either side.
How to use sequence files Sequence files can be used in target scheduling. In the target scheduling menue once the targets has been set, in the movement parameters choose dsq. Then browse for the dsq file created.
Run the Schedule by clicking OK. Once the schedule has run create a schedule detailed report. Cash flow, strip ratio, quality etc can be reported for each sequence files. It is essential to compare the effect of using the different mining sequence. For instance below is a comparison based on cash flow from different sequence. Similar graphs can be done for strip ratio in each period, and compared.
The graph below is for individual scenario with a particular sequence file.
Sequence files can also be used in detailed equipment based scheduling. In the Equipment movement option choose Movement files, change the file type to all files. And select the sequence file. The equipment will then follow the generated sequence.
Similar sequence files can be generated for Dumping. Contact GEOVIA for details.
Dassault Systemes has combined the powers of SIMULIA isight and Minex to simulate different mining sequence and help you optimize your mining schedule. Please contact GEOVIA for more details.
Ranajit is a qualified Mining Engineer with over 22 years of experience in mine planning, consulting, operations, logistics, exploration and feasibility studies. Ranajit has previously worked for the Steel Authority of India, Santa Fe Mining in Chile and JSW Steel in India. He specializes in GEOVIA Minex and Surpac.