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Archive for the ‘Engineering – General’ Category

I am told that yesterday’s posting was hard to read.  So rather than write tonight, let me simply post some pictures I took from a public road of tailings facilities closed by the Peruvian regulators.  Not sure how long the gabion baskets will last.

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The exterior surface of most tailings, waste rock, and heap leach facilities include:

  • A top deck which is the flatter surface that forms the top surface of the facility. This is usually sloped at between one and five percent, primarily to promote runoff.
  • The sideslopes which are easily covered if they are inclined at about five horizontal to one vertical (5H:1V) but which in practice may be as steep as 1.4H:1V.

Covers on the top deck are less subject to erosion, slope instability, and soil creep than covers on sideslopes. Thus different covers may be appropriate at the same facility on the top deck as compared to the sideslopes.  Here are a few idle thoughts on sideslope covers for mine waste facilities. (more…)

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Subaqueous disposal means placement of tailings into or beneath a water cover. Deposition of tailings into a lake is the most common subaqueous method. In many instances the embankment dam is constructed as a water retaining structure and the impoundment is filled with water into which the tailings are discharged. (more…)

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Mike Jacobs of Goldcorp presented the keynote address today at Paste 2014 in Vancouver.  His topic:  Where mining meets the public–and why water is so important? He told us that Goldcorp annually publishes the statistics of the use of water at all its mines.  Commendable. Then he told us of the First Nations prayer ceremonies at the opening and closing of water seasons at their mines.  Incredible. (more…)

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The first official day of conference sessions at the Paste 2014 conference here in Vancouver.  Sean Wells, Director of Research for Suncor presented the opening keynote address. I cannot possibly here recount all he said.  All I can do is note a few points that he made that stuck with me.  In due course, his PowerPoint presentation will be available through InfoMine.  Get it and take deep thought over it, for his points are provocative, timely, and scary. He noted that the problems of oil sands tailings management are all about scale.  They oil sands produce so much tailings that the shear volumes and areas needed introduce problems not encountered in conventional tailings management.  I have heard it said that the two oil sands mines, Suncor and Syncrude, produce more tailings per day than the combined total of all the other mines worldwide.  His point is made. (more…)

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Day one of the  conference Paste 2014.   Actually the actual conference begins tomorrow.  Today there were short courses and meeting of friends and fellow travellers on the mining journey.  The most beautiful was a lovely lady from Brazil who is studying at the university of British Columbia for a semester and will be a mining engineer in a year or two.  We chatted over lunch and if she is, as I believe she will be, the future of mining, the profession is in good and beautiful hands. (more…)

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Lesson learnt: in all O&M tailings management manuals put in a requirement to observe the penstock more carefully when tailings discharge water is not going through it—look carefully to see if water from another source is exiting the pipe and find out why.

This is a new lesson learnt. This is something I had not before now thought of.  But on the basis of what I saw and did today, a necessary action.

Add it to your O&M manual.

Here are some pictures of this situation:

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If you have a penstock and seek to know more, contact me.

 

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More than twenty-five years ago, I spent six months in Oak Ridge, Tennessee opening the Jacobs Engineering office.  Then we won a job that required me to move to Pasadena, California.  This week I am back in the state and see much change.  Highway 40 from Oak Ridge to Knoxville was a quiet road.  Now it is continuous commercial development and an eight-lane freeway.  The weather is still perfect and the people still have that wonderful can-do attitude.

Those miners I have been with this week are so American.  Their attitude is always:  that is a great idea–we can do it; but here is a better idea–what do you think?

So we leapfrog from issue, to question, to idea, to analysis, to solutions.  And the outcome is a positive advance based on mutual agreement.

Did you know that Tennessee is a mining place?  One of the largest producers of zinc concentrate?  Some of the mines are one-hundred and more years old.  Of course there is still some coal mining, but I know little of that.  As the picture above shows, natural gas is a thing I thought not off way back then.

The food is great:  meat and sauces, fries, and sweet tea.  Then there are those many variations of Jack Daniel’s that I cannot get elsewhere.  Right now I type to the tune of Winter Jack: “A seasonal blend of apple cider liqueur & Jack Daniel’s Tennessee whiskey.”  Magnificent.  No wonder mining is so smooth.

I am told the regulators are great people to work with.

So the mines advance with the usual issues to be dealt with: too much vegetation in waterways & spillways; seepage through rock embankments; tailings pools too close to dikes; the threat of hurricane-induced probable maximum precipitation; and the New Madrid earthquake that makes this a region where seismic stability analyses are no deal and a big deal.

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Today my attention was directed to the new Guide For Mine Closure Planning.   The guide is prepared by IBRAM which is short for Instituto Brasilero de Mineracao, or in English the Brazilian Mining Association.  Well worth downloading and perusing if your interest lie in mine closure. The guide is focused around these seven guidelines: (more…)

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There is much talk these days about how high tailings facilities are being designed and constructed.  Short-term memories at work.  In 1980, I designed and permitted a tailings facility to 1,000-ft high.  It never got built.  But here is its story, nevertheless. (more…)

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