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Introduction Ore Processing Fire Assaying

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  1. One of the series of powdered rock samples is weighed in preparation for adding to the fire brick crucibles.The whole flux is thoroughly mixed with a known amount of carefully sampled powdered rock in a fire brick crucible.  This crucible withstands the heat of the furnace and is thick enough that only some of the inner wall reacts with the fluxes to become a part of the glass slag, which floats on top of the molten lead.
  2. The weighed powdered rock sample is added to the crucible. The assayer keeps a list that relates the sample identification to the position of the crucible.The crucible is heated so the  mixture of flux and rock sample melts (at a temperature lower than that of the rock alone as controlled by the flux composition).  
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