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Plant Designed using Unrepresentative Sample (9 replies)
You need to understand geometallurgy of deposit:
- samples representative of deposit for grade and spatial location, based around ore types, miner plan, etc.
- comminution and flotation tests on these samples
Sadly what you are seeing is very common. Often in an operation, the feed will change, and this can happen for many reasons, and change in mineralization is a very common issues. For this reason many large operations continually run test on the ore (current and future from drill programs) to verify how it will respond. Performing the same tests you would have done to design the plant is a very good idea. This can also tell you what you may need to change (grind time, reagent type and dosage, and similar). You will be generating your own grade and recovery curves, which are unique to each operation.
Often simple changes can yield significant results.
http://www.911metallurgist.com/geology-prospecting/geological-sampling-theory
http://www.911metallurgist.com/geology-prospecting/representative-sample-selection
The point is that the company who built the plant needs to guaranty recovery/grade based on a mineral composition, now the mineral has change and we need to find a way (test, mineralogy etc) to compared the pilot test done with test with new mineral and find the curves. This is the common practice I supposed. I am not referring to the future work based on the changes of the mine in future. Thanks to all.
Some one needs to perform the testing. The company who designed and built the plant would base any guarantees on the metallurgical data given in the original tender, if the feed to the plant does not agree with this data, some one has to perform tests to see how it should respond and what changes may and can be made to improve the results. But in all likelihood this will occur again during the life of the operation and should be planned for.
Was there any metallurgical variability testing performed as part of the flowsheet development program which led to the plant design? If so, then it should be possible to assess current plant performance based on the variability samples from the areas currently being mined.
"now the mineral has changed"- Ore not change 🙂 (*) But I guess the idea. Ore for startup is different to ore tested in the past. Do you know where ore was extracted for those tests? I recommend to study the variability of ore in mine (a geometallurgy study) looking for similarities ,and review the mining plan according to them in order to guarantee results for first years. Meanwhile, new tests are mandatory.
(*) A possible exception is that "mineral" has been altered by weather, like old tailings or heaps.
In fact the pilot test for designing the plant was done only with one expected mineral (lower grade) but since the time was exceeded to start the plant, now the mineral has lower grade. We are going to study the changes on mineralogy, liberation etc to compared with the original sample. And develop a curve showing recovery/grade with the original and new sample. This is important due to the guaranties given by the constructor , so thanks to very one.
Your approach - one of comparing the grade-recovery curves for the original sample and the current feed is appropriate.
It is unclear if it is intended to perform new tests with the original sample, or simply use the data obtained with the original sample. Either way, the test program will have to include a component to manage sample aging (if original sample) and subtle change in the base experimental response due to differences in equipment, technician(s), and/or test procedures. Otherwise, it will be very difficult to prove without doubts the findings - especially if the results are such that the penalty clauses under the performance guarantees would be applied.
Yes I will perform a test at the lab. with the new mineral grade (lower in grade) and also compared the original results with the mineral (6 years ago) and finally to have the results on running the plant (start up new plant). thanks to all. Of course penalties would be applied unless we can demonstrate that the mineralogy has change, grace , liberation etc of the new mineral compared with the old one, so i kind of curves i should developed to show how the new material affect the process.
I agree that the retention time is of course depend upon some other factors i.e the nature and behavior of the mineral subjected to processing, feed volume, pulp density, liberation size, the medium of classification and the categories of concentrate, middling and tailings.
We started a new processing plant, the feed grade is much lower than the project expected (6 years ago) and accept the plant based on the original recoveries. We have another Plant Designed using Unrepresentative Sample!
How we can improve the recovery and expected concentrate grade because this different feed grade of mineral to be process now? We are suggesting to run laboratory, with the new mineral and compared the liberation, etc, please comment.
I think testing the new material and comparing with original mineral use for the design would be a solution, however I need a way to compare both situation with new and old text. Any formula grade/recovery curves for different material?