| abstract |
The concentration of a desired material in pieces of ore is determined by coating each piece with a fluorescent material that selectively adheres only to the exposed surfaces of the desired material. The pieces are then individually illuminated by ultraviolet radiation to fluoresce the selectively coated material. First photo-multipliers sense the magnitude of the fluorescence and a second photo-multiplier, which detects the shadow of the ore piece, yields an output proportional, after inversion, to the cross-sectional area of the ore piece. The magnitude value is then divided by the area value to indicate the concentration of the desired material in the ore piece, which may serve as a basis for automatically separating the pieces for further treatment. |