Today the issue of the cost of tailings management arose yet again. I have previously blogged on this topic–see this posting, also repeated below if you choose not to redirect. Today in this posting, I repeat two of the answers I received from people who may know. Contact me if you seek their names. Here is the first answer to my queries:
We have the following:
- Semi-custom cost models for the design, construction, operation and closure of slurry and dry-stack tailings facilities (these are pretty detailed and build up unit rates using manpower and equipment rates)
- A basis for doing statistically based cost estimating to accommodate uncertainties in unit costs, methods of tailings deposition and, if necessary, tailings disposal sites
- Results from the above models that we have based on projects we have designed for Canada and Argentina
As you know, the unit costs of tailings disposal varies by an enormous amount depending on the country, geology, climate, total volume, pre-conditioning, disposal method, site geometry, tailings chemistry, available construction materials, quality of the engineering, etc. We have seen ranges from under $2/t for large desert mines, to up to $15/t for small mines in very difficult circumstances. The above models allow one to break down the costs in a systematic way to see roughly how much the individual factors are contributing and why there are differences from project to project.
Here is the second reply:
We do not have benchmark cost data for tailings. As you well know, the issue is that every tailings dam/impoundment is project specific. Not only is terrain a major factor, but so is the climate, waste composition, etc.
That being said, this is the type of project that we can provide on a consulting basis. We can either put together a series of potential tailings projects that address all of the earth moving, liner, catch basins, etc. and provide a CAPEX and sustaining CAPEX, OPEX summaries.
The best approach would for us to develop models to your specs. We can put together models that will calculate the earth moving requirements, supplies and then produce a series of tables with the equipment, labor requires, supplies (fuel, liners), etc. We can also provide you with either customized programs using our Sherpa software platform.
Here is my previous posting on this topic:
It costs between $1 and $40 a ton to build, operate, and close a mine tailings facility. That is as specific as I was able to be when answering a question today in response to an enquiry from Australia. There is a surprising paucity of data out there on the cost of tailings management. We have details of salaries & wages. We know the compensation of mining company executives. We know how much it costs to engage and retain even the most expensive consultant. But we have no data-base on tailings costs.
There are many reasons for this mystery. First is that tailings management costs are site-specific. Second is that they are not very exciting—most folk want to know what they should earn, and care little about tailings costs. Third, nobody has set out to gather and publish the data. Forth, most mines probably do not know or care.
Maybe we should plead with the folk at CostMine to address this cost deficiency. Maybe CostMine could survey mines and ask them what their tailings costs are and publish the data to our edification & delight.
Failing that we are left with the old-fashion methods: list operations; list quantities; establish unit rates; and work it all out. There is only one man that I would trust to do it accurately. Contact me if you want his name.
Keep in mind that as in all mining estimating, you will have to attend to varying degrees of accuracy depending on the mine planning phase. It in prefeasibility, the accuracy is low; if in feasibility, the accuracy is reasonable; if in detailed design, the accuracy should be precise; if constructing & operating, the costs are actual; and if going to closure, well best shudder, pay, or say you are bankrupt.
I would guess that in a nice climate, the cost of conventional slurry, hydraulic fill tailings deposition is $1 to $3 a ton. Add $2 to $3 if the climate is arid and you have to desalinate or pump long distances. Get involved in thickened tailings and the promise (false) that it offers, and you must add $3 to $5. I do not comment on paste tailings on surface, for I do not believe it is viable at any cost.
If you choose to filter press and dry stack, you are in for $5 to $10 a ton. But consider the cost savings associated with a lesser water cost. And beware the potential need to add cement to control moisture content and get a required strength. Cement is expensive.
And if you go for polymer amendment remember the sky is the limit. Polymer amendment works—that I can attest—but even the consultants are costly.
In conclusion, do not seek industry averages, for they are meaningless. Get a qualified cost estimator and work out the detailed costs.
I think the reason companies don’t give tailings costs is not because they don’t care but because tailings is not a stand-alone operation. For example, thickeners, pumps, pipelines are often included as part of the process plant cost center. If waste rock is intermittently used to raise the dam, this may be included in the mining cost, also support equipment costs (eg backhoe) used on tailings may actually belong to the site services group and included there. So if a company reports a tailings cost it may not include all costs. One could dig through the various cost center numbers to pull out a tailings cost but it gets complicated to track intermittent costs on a monthly basis.
Most companies track the labour and material costs to place tailings. It’s pretty small. One mine I worked at spent about $1 per tonne in capital, but the TMF also was used to store PAG mine waste. When compared to overall cost, TMF costs are very small, and perhaps that’s why they don’t receive a lot of attention.
edit this on May 9, 2013 at 6:00 pm | Reply The Cost of Mine Tailings Management « Engineering.BlogNotions – Thoughts from Industry Experts
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As mentioned in the above comments, so many of the activities relating to tailings dams can be absorbed by the mining operation as a part of their day-to-day activities. Since every tailings dam is unique, there are always additional costs that apply to that environment, mineralogy, permitting, etc. that cannot be surveyed or generalized in a model. We can create cost models for the actual activities – earth moving, blasting, liners, etc. but we can’t model the permitting, local opposition, etc.
Jennifer Leinart, CostMine