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Thread: Mud Rush phenomina - solid/plastic transisition in ore passes

  1. #1
    Posted by Phil Lovering on November 01, 1999 at 21:55:13:

    I am trying to find information on the phenomena known as a ‘Mud Rush’. This occurs in the ore passes of underground mines where the material in the ore pass suddenly changes from a sold mass to a virtual liquid. When the ore pass is opened the material flows out engulfing the people and equipment in the exit area.

    I am researching this as I believe that the Particle Size Distribution and moisture levels play a significant role and urgently need to find a method of preventing any re- occurrence

    Thank You

    Phil Lovering




  2. #2

    Re: Mud Rush phenomina - solid/plastic transisition in ore passes

    Posted by Joseph A. Dos Santos on November 03, 1999 at 16:25:01:

    In Reply to: Mud Rush phenomina - solid/plastic transisition in ore passes posted by Phil Lovering on November 01, 1999 at 21:55:13:

    Dear Mr. Lovering,

    This is a long shot. It may or may not be of help.

    In soils mechanics their is the phenomenon of quick clays. These are clays that are very solid and stable in-situ but when disturbed, say by heavy machinery, they liquify and run like mud. There instability is often linked to their geoligic history. Stabalizing chemicals have been leached out of these clays. This is well known in the Scandanavian countries where undersea clays have uplifted and the salt has been leached out over geolgic time.

    There is the story of the German tanks and equipment being bogged down during the invasion of the scandanavian peninsula. The Germans studied their history and were able to stabilize the ground by spreading salt ahead of their advancing equipment.




  3. Re: Mud Rush phenomina - solid/plastic transisition in ore passes

    Posted by Lyn Bates on December 08, 1999 at 10:41:45:

    In Reply to: Re: Mud Rush phenomina - solid/plastic transisition in ore passes posted by Joseph A. Dos Santos on November 03, 1999 at 16:25:01:

    Liquifraction of wetted particulate materials is not uncommon in the transport of ores. Similar changes of state occur in the 'working' of centrifuged materials and filter cakes and other damp powders. 'Quick clay' is a related phenomenon in soil mechanics and the infamous Abervan disaster took place when a spoil heap was infiltrated by excess water. In each case the capacity of the fluid to fully occupy the voidage space in the bulk relieves the particle to particle contact pressures and allows the material to behave as semi-fluid, of highly variable viscosity according to the degree of freedom of the particles to rearrange and shear within the fluid media.

    Warren Spring Laboratories published wome work on the safe transportable moisture content for ores, following an investigation into the sinking of vessels made unstable by the settlement of bulk cargo to the extent that the moisture occupied the voidage and allowed the rolling of the vessel to move the cargo. Air entrainment or injection produces flushing and flooding by similarly displacing the particles from intimate contact pressures.

    The problem of evaluating this behaviour is that the nature of the particle structure, and how this may re-arrange to higher densities, has a high bearing on the materials stability. For example clays have a plate-like form and can therefore be stable under load at a particular moisture content, until an applied shock re-alignes the particles from a random to a more parallel arrangement.




  4. #4

    Re: Mud Rush phenomina - solid/plastic transisition in ore passes

    Posted by Paul Griffin on December 23, 1999 at 01:33:42:

    In Reply to: Re: Mud Rush phenomina - solid/plastic transisition in ore passes posted by Lyn Bates on December 08, 1999 at 10:41:45:

    The mud rush in metalliferous ore passes is well recorded in the mining literature.Refer to these excerpts from Western Australias Mines Departmenthttp://notesweb.dme.wa.gov.au/exis/SIR.NSF/85255e6f0052056085255d7f00607219/a702a32c41580e714825609d004d6b9d?OpenDocument )and (http://notesweb.dme.wa.gov.au/exis/SBULL.NSF/85255e6f0052056085255d7f00607219/6a10563c87ef79a64825609d004a893b?)
    The rush is generally due to an accumulation of water in the ore pass, either due to flooding or water burst on an upper level, drainage of water from the rock in which the ore pass is excavated, or deliberately added to overcome a blockage. It is common practice in the industry to assist the movement of blasted rock both in the stopes and in the orepasses by using water, often to wash away the finer rock, which then frees the bigger rocks to fall.
    I think it is important to differientiate that though called mud rushes, they are usually not due to liquifaction of a soil as such, becuase the ore is generally blasted or crushed hard stone.
    When the movement of the ore starts, the fine component of the broken ore forms a slurry, which then transports the larger rock.

    The natural phenomenom of a LAHAR, which is a landslide associated with the collapse of a volcanic calderera lakes is a similar event. I understand some lahars in the province of Taranaki in New Zealand have been recorded which travelled over 20km, and transported rocks the size of a house.

    Mud rushes have occured in mines which are associated with soils or processed tailings, notably Mufulura (sp?)in Zimbabwe.



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