砂金粒度探采对比及对砂金勘探地质品位的影响

我国砂金粒度在探、采两阶段具有明显不同的特征，开采阶段拉勘探阶段砂金粒度具有增大的趋势，且随着砂金粒度的增大，探求两阶段相对应的砂金质量分数渐趋一致．砂金粒度变化是影响砂金勘探地质品位贫化的主要因素，特别是粗粒金（＞1mm）含量的多少，即砂金粗粒系数影响着砂金品位误差系数的变化．据统计我国72％以上砂金矿不同程度地存在着砂金勘探地质品位贫化的现象，为此应重新开展砂金”回头看”工作．

Grain Size Comparison of Placer Gold in Exploration and Mining and its Effect on Exploration Grade

The grain size of placer gold has distinct features in the two stages of exploration and mining. It has the trend of increase from the exploration stage to the mining stage. With the increase of grain size, the weight percentage of placer gold corresponding to these two stags gradually becomes concordant. The variation of grain size is a main factor which innuences the dilution of exploration grade of placer gold. The number of coarse-grained gold (>1 mm) , the coefficient of coarse grain, affects the error coefficient of the placer gold grade. According to statistics, the dilution of grade in the exploration for placer gold exists in more than 70% of placer gold deposits in China, so further work for placer gold should be done.