Paste 2013 is done. I am told there were 380 attendees and 28o were turned away as they sought to come too late when all was full. So a successful conference! The proceedings is some 700 pages long and my name is amongst the editors. Indeed I read all the papers, reviewed many, and gave advice on editing of many. I made mistakes: I allowed some in that should have been elsewhere: I canned some that should have been in. That is the fate & verdict of a reviewer and editor.
If you were not among the 380 penned in a substandard hotel in Belo Horizonte by protestors, no matter. You can still learn as much as those who braved the trip and travails of Brazil in revolt and a revolting hotel.
Next week, I and a few selected friends present an EduMine webcast on advanced tailings management. There is still time to register and join us from the comfort of your office or home to hear the ideas that are new and controversial in tailings and the ideas and disputes so politely suppressed at Paste 2013. Do a Google search of edumine tailings Caldwell to get the link and data. I would be most honored if you joined us. And even now, if there is some topic you would like covered & addressed, let me know and I will sure have an opinion and give guidance.
Here is an email I got after the Paste 2013 conference from one heretic who sought to storm the portals of worship:
I have serious restrictions when you import technology or methods from one country or region to others without considering the differences that really happen. In this specific case of tailings disposal sometimes practitioners don´t understand or don´t see big elements that can lead to different conclusions or solutions, as seismicity, rain, deserts, flat terrain or abrupt topography, costs, labor, legislation, etc. Besides that, there are many aspects about paste behavior that are contradictory as liquefaction, dust, erosion by surface waters, oxidation, sulfatation, etc. Some authors say it can happen and those “paste lovers” usually point them as benefits or advantages. This was the objective of my paper: say to those that think that paste is a good solution for the Brazilian mining sector that it must be evaluated with care. It has some aspects that are positive and others that are negative. It is not the best alternative: it is one alternative to be considered. Just that.
The point is that there is a religion of paste and thickened tailings. This is unhealthy: science, the basis of engineering, is o’erturned in the interests of a ruling priesthood whose livelihood and first-class plane tickets depend on devotion to the cause and promotion of paste as the only solution.
I did not go to the conference; who wants to travel those vast, uncomfortable miles to hear hymns and psalms? Instead I went to a mine where the false promise of paste is manifest. Yet the mine is still in thrall to the mystery and still keeps the worship rituals alive. They cannot tell the truth: paste will not work and will not solve our problems. The gods are to be obeyed and sacrifice is still necessary!
I wonder why? Is this a meme? A madness that grips the human mind and pushes out reason and rationale thinking? Is this a lucrative pastime that greedy, lazy consultants and lazier clients will not eschew? I know not. I know only that this madness persists.
Here is more from the statement that was not made:
It must be clear, to everyone that works with tailings disposal, that paste is just an alternative to other methods. It is not the best one. It is not the worst. It has advantages and disadvantages. It seems to be necessary to state this because when you read many papers dedicated to paste that is not the impression that comes to your mind.
Just to give some examples, here are some references.
Hart and Boger (2005), in their keynote address for Paste 2005, Chile, mention about “suspensions at a high concentration, which in fact is where the industry must move if it is going to recover more water and effect more sustainable practices”. The use of filtered tailings certainly represent a better solution to recover more water and as a more sustainable practice.
In the same paper they also mention that “There have been on average five tailings impoundment failures per year since de 1980´s (Mining Journal Research Services, 1996): all could have been avoided through the use of paste or thickened tailings technology”. Of course this is a biased conclusion, because those failures certainly could be avoided if the dams have been well designed, constructed and operated. If it is not the case, what to say about the hydroelectric dams?
At this same seminar, the paper presented by Shuttleworth et al. (2005) refers to the advantages of using paste at the Bulyanhulu Project, as maximization of water recirculation, reduced risk of failure, minimum access time onto the tailings surface, increased storage capacity, reduced costs with construction of conventional tailings dam, progressive reclamation. It is known that before the use of paste, the tailings are filtered. If a filtered deposit is formed, instead of paste, all of these advantages would be increased, but the comparison uses only the slurry form of deposition.
When it is mentioned that the thickened tailings or paste reduces the water consumption, indeed it is unnecessary. Everyone working in the mining industry knows that if you install a thickener in your plant you will recover more water in the plant. Why we don’t see many plants with thickeners? In all economic analysis that we have participated, years ago, we never arrived to the economic benefits of putting the thickeners. In all cases the investment and the operational costs, mainly with flocculants, brought to net present value, resulted more costly than to discard the slurry and recover the water. And in Brazil, for example, normally you need another dam to store water for plant supply: in some projects there is a water dam, specific, and in others the tailings dam is that structure, to compensate the dry and rainy season.
But when you compare a plant in the Atacama Desert with another in a rainy region of Brazil, the importance of recovering the water in the plant or in the dam reservoir is completely different.
Also, quite often comparisons of paste or thickened tailings are made with slurried tailings disposal, and systematically showing that (again) paste is the best alternative.
In my opinion all these balances and comparisons have low values, because the reference bases change from place to place. Ex.: the cost of energy is different in Brazil as compared to Australia or to Peru; the climatic conditions in Brazil are different from Iran, or from the north of Chile or from Australia; the relative position of the plant and the TSF is different from place to place, or in some cases the plant is at a higher elevation or it is too far from the TSF, and in other places the contrary may be encountered. The cost of labor is different in Brazil as compared to Peru, or Australia, or the United States or in China. The cost of equipment is also different in Brazil when compared, for example, to Argentina or China. The cost of land is completely different in the area of the iron ore quadrangle, in Minas Gerais state, in Brazil, than it is in Australia, in the desert of Chile or even in other regions of Brazil. The availability of water also is very different if one compares a dry region and a rainy area (example: the desert in Chile, with Zero rain per year, and some areas in Brazil, with 2,000 mm/year). Also the topography is variable from place to place, with flat areas in Australia and mountainous regions in Brazil, with valleys and steep hillsides.
Only these aspects, not to mention others, are sufficient to destroy a successful alternative in Australia if you want to transport it to Brazil, or to another country with different conditions. So, evaluate the success of an alternative in one country and compare it to another country, certainly will result in comparing apples and onions. The majority of aspects are site specific: water reclaim, dust, erosion, beach profile, closure, acid generation, lower investment (CAP
Then I talked at length with KL who said that neither he nor Geoff Blight are welcome at Paste conferences for they both state that the same benefits can be had by judicious tailings management. He laughed and we drank a toast to truth and civil disobedience in the face of religion and upper class privilege.