Mine tails dewatering - How to extract more water??

[BT2000]

Our tails contain 50% water and are very fine (90% < 150microns) We want to extract more water before placing on the tails dumps, for two reasons; to recover more water and to increase the density of our tails dumps. Recovering more water will relieve pressure on our water supply. Increasing the insitu density of our dumps will also increase the useful life of our tails dams. The density we acheive in our dumps currently is ~1.37t/m3

Any advice/experience would be appreciated

 

[PBroad]

I would like a little more information before giving site specific suggestions but what you may be looking for may be paste deposition of tailings

http://www.tailings.info/paste.htm

You may want to read some excellent papers on why dams fail

http://www.tailings.info/dams.htm,

http://www.pincock.com/Perspectives/Issue11-Tailings.pdf

or

http://www.wise-uranium.org/mdas.html

If you have a long transport distance removing water before the dam may not be the best solution. You may want to instal dewatering wells around the dam, or look at explosive compaction of the dam so that you can expand its capacity. INCO in Sudbury did this in 2003, but if not in the area you may want to talk to any soils compaction expert who uses explosive compaction (There was a papet on this in CIM Bulletin Dec 2003)

broadpeng@rogers.com

 

[Kivi]

This is a big question, and as PBroad mentioned, transport distances also play a part as using higher densities of slurry requires positive displacement pumping which is more expensive, but lower cost to run/per solids througput. Paste or higher density tails deposition on surface is the trend for overall cost savings. It is dependent on factors at the location. One of your factors is water, so as you have done you should look into this. Hire a large consulting company (if you have LOTS of money)or get a small scoping study done by an independent consultant to get you on the right track. This will save you tons of time. the small studies can usually be passed on directly for preliminary engineering.
Regards,

 

[BT2000]

Kivi

As you mention it we have an expert coming to see us tomorrow!

The issue of pumps is another issue we are working through. Can we set up pumps in series, about 1.5km apart without having cavitation problems? I know that we can use small tanks and re-mixers to maintain positive head on all the pump inlets, yet a cheaper option would be to have them all on one line and use some type of controllers & VF drives to maintain positive inlet head at each pump. Can you think of a company that specializes in this type of installation?

 

[Kivi]

bt2000,
depends on which continent your project is on.

 

[BT2000]

Australia

What information do you have?

 

[Kivi]

Patterson & Cooke out of South Africa are very good at that sort of thing - pumps and piping of slurries. But in Australia, I am not sure of who would be good, there are a ton of consultants down there.
Good luck

 

[Backfill]

BT2000,
We were not as fine, had a 65 mesh grind, but our overall tails density was very close to yours when we switched from sub-aqueous to sub-aerial deposition. Nothing fancy on the tails pumping side, just diligent deposition cycling and water management on the tails.

The water reclaim benefits occured rapidly. The design intent was to switch from a clearwater pond against an earthen dam to a 'solid' beach against the dam, and ultimately permitting upstream construction. It took about eighteen months, but worked nicely. There were two benfits expected and realized: 1) construction costs went from engineered earthfill to coarse rockfill. 2)Tails densification worked well, allowing 2.5 times the original amount of material within the originally permitted footprint.

This was at 7,000 ft elevation in the state of Utah. Given your additional many months of sun, shouldn't have too much difficulty in Australia. Incidentally, the original literature (and consultant) guidance on our effort came from South Africa, though through their Denver office. The only discrepancy we had with them was we said we could build upstream, which we did. Its now completed and successfully reclaimed. Deer, bunnies, whole nine yards. Squirrels like the rocks.

Food for thought, if your material will release its moisture under sunlight. We diminished our overall water requirements even though we were increasing the effective evaporation across the tails beach. If you need the water in your plant, you may have to go the paste route as the threads above indicate. Higher pumping costs, but with your grind the wear shouldn't be too bad.

Good luck. Give me a holler if you need more detail.

 

[BRT549]

I had a similar problem dewatering calcine tailings. A Derrick vibrating screen did a good job bumping up the % solids, and we used a flocculent to improve water clarity and get even drier filter cake. I think they are an established presence in Australia, although they manufacture in Buffalo, New York, USA. They have a number of models to choose from, and have a good testing facility.