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Re: [NGMMG] Re: Virginia and Truckee

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  • Ken Ruble
    This is very interesting. I hope you post more like this in the future. I would particularly like to know how flotation works. I know about
    Message 1 of 56 , Apr 28 8:23 PM
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      This is very interesting. I hope you post more like this in the future. I would particularly like to know how flotation works. I know about hydrophilic/hydrophobic but I don’t understand why this lifts out the gold but not the non-metalics.
       
      Ken
       
      Sent: Sunday, April 28, 2013 8:13 PM
      Subject: [NGMMG] Re: Virginia and Truckee
       
       

      I missed participating in this discussion, as we were on vacation in New Zealand, but maybe it is better late than never?

      I am a geologist, and have worked extensively in Nevada, including in exploration and production at gold mines in the Elko area. Most of the gold deposits in northern Nevada [which is the 4th largest gold producer in the world] are often referred to as "micron" or "no see'um" as the gold is very fine grained, and often tied up in arsenical pyrite. As such this mineralization never formed placers that the early prospectors found.

      The current Nevada gold rush started in 1962 with the discovery of the Carlin mine, but there wasn't too much interest [$35/oz old price] until the mid to late 1970's when Freeport discovered the Jerritt Canyon mines [and the federal control of the gold price was lifted. After that time exploration [and discovery increased, with considerable success achieved by Newmont, Barrick, Freeport/Independence/Anglo Gold, and Placer Dome in particular.

      Up until about 1993, when Independence discovered and developed the Murray mine at Jerritt Canyon essentially all of this mining was done by open pit methods, but as the large, near surface targets were explored drilling focussed more on deeper deposits that are mined by underground methods.

      Unlike historical underground mining, very little of the current generation of underground mines have shaft access; instead, they are access through declines or "ramps". While the declines are longer, it is far less costly to access the deposits in this manner. It also permits the use of larger-scale trackless haulage equipment.

      Essentially all of these mines use some type of ground support for the mine workings, but is most often rock bolts, screen mesh [essentially chain link fence type material] and "shotcrete", which is a concrete sprayed onto the mine workings. There is essentially no timber used anymore in these mines.

      The underground mines in northern Nevada are large scale operations, regularly producing more than 1,000 tons per day, dwarfing the production of the historical shaft mines that we model. In fact the advancement of modern mining technology bears little resemblance to what we focus on with our modeling.

      TED

    • Ken Ruble
      This is very interesting. I hope you post more like this in the future. I would particularly like to know how flotation works. I know about
      Message 56 of 56 , Apr 28 8:23 PM
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        This is very interesting. I hope you post more like this in the future. I would particularly like to know how flotation works. I know about hydrophilic/hydrophobic but I don’t understand why this lifts out the gold but not the non-metalics.
         
        Ken
         
        Sent: Sunday, April 28, 2013 8:13 PM
        Subject: [NGMMG] Re: Virginia and Truckee
         
         

        I missed participating in this discussion, as we were on vacation in New Zealand, but maybe it is better late than never?

        I am a geologist, and have worked extensively in Nevada, including in exploration and production at gold mines in the Elko area. Most of the gold deposits in northern Nevada [which is the 4th largest gold producer in the world] are often referred to as "micron" or "no see'um" as the gold is very fine grained, and often tied up in arsenical pyrite. As such this mineralization never formed placers that the early prospectors found.

        The current Nevada gold rush started in 1962 with the discovery of the Carlin mine, but there wasn't too much interest [$35/oz old price] until the mid to late 1970's when Freeport discovered the Jerritt Canyon mines [and the federal control of the gold price was lifted. After that time exploration [and discovery increased, with considerable success achieved by Newmont, Barrick, Freeport/Independence/Anglo Gold, and Placer Dome in particular.

        Up until about 1993, when Independence discovered and developed the Murray mine at Jerritt Canyon essentially all of this mining was done by open pit methods, but as the large, near surface targets were explored drilling focussed more on deeper deposits that are mined by underground methods.

        Unlike historical underground mining, very little of the current generation of underground mines have shaft access; instead, they are access through declines or "ramps". While the declines are longer, it is far less costly to access the deposits in this manner. It also permits the use of larger-scale trackless haulage equipment.

        Essentially all of these mines use some type of ground support for the mine workings, but is most often rock bolts, screen mesh [essentially chain link fence type material] and "shotcrete", which is a concrete sprayed onto the mine workings. There is essentially no timber used anymore in these mines.

        The underground mines in northern Nevada are large scale operations, regularly producing more than 1,000 tons per day, dwarfing the production of the historical shaft mines that we model. In fact the advancement of modern mining technology bears little resemblance to what we focus on with our modeling.

        TED

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