| 摘要 |
A method of and apparatus for sorting pieces or particles of radioactive ore where the particles are moved through the apparatus in an asynchronous or non-constant manner. The particles are moved one at a time to a position in front of a radiation detector where they are temporarily stopped. The counts from the particle are accumulated with respect to time. In a control unit of the apparatus there is data representing a cut-off grade radiation rate and early upper and lower decision limits are established with regard to the cut-off rate. As soon as the accumulated count/time ratio from the detector exceeds the upper limmit or falls below the lower limit, the control unit is able to provide a decision to accept or reject the particle. If the particles are not closely sized then the size of each particle is determined before it is positioned in front of the radiation detector and the size determination is used to modify the cut-off grade and upper and lower early decision limits. Particles which are well above cut-off or well below cut-off (i.e. above the upper early decision limit or below the lower early decision limit) are disposed of very quickly. Those particles having a value close to cut-off assessed for a longer time. A maximum assessment time is determined for the ore and accuracy required. Because the particles may be assessed for only a short interval, the throughput is increased considerably over prior art arrangements where the feed rate is synchronous or constant and the rate of feed is set for assessment of the smallest and most difficult particles handled. |
