Fractal Principle of Mineral Deposit Size Forecasting and Its Implication for Gold Resource Potential Evaluation in China

Mineralization distributions are very heterogeneous in nature. As large orsuperlarge mineral deposits are quite rare whether in time or in space, it is difficult to detectall the largest mineral deposits in a region in a limited period of time owing to the restriction oftechnology and exploration degrees-this is called 'not all discovered'. However, all discoveredlarge, especially superlarge, mineral deposits generally have a complete census in the geologicalliteratures. On the other hand, not all discovered small mineral deposits are recorded in thegeological literatures because for economic reasons people have not much interest in them-this iscalled 'not all recorded'. This practice often results in the observation truncations, that is, thedata points near the two ends in an observable population, which is obtained by fitting a power lawsize-frequency distribution to discovered mineral deposits in a given region, show concave-downdeparture from the correlation line fitted. The authors suggest that the size and number ofundiscovered deposits may be forecast by fitting a fractal size distribution to discovered mineraldeposit sizes between the upper and lower truncation observations and then extrapolating thescale-independent area to deposit sizes larger than the upper truncation limit. Based on thestatistical results obtained by the fractal size-frequency distributions of 394 discovered golddeposits with sizes greater than 2 t Au in China and 83 known gold deposits with sizes over 0.3 t Auin the Jiaodong area of China, the authors forecast according to the present commercial standardsfor gold ores that the total resources of undiscovered gold deposits ranging in tonnage from 50 to2000 t Au are more than 4500 tin China, and that in the Jiaodong area of China the total resourcesof potential gold deposits with sizes in the range of 30 to 650 t Au are about 700 t.

Mineralogical and Active Mechanical Excitation Characteristics of Filled Fly Ash Cementitious Materials

To reveal the influence of mechanical activation on the performance of fly ash, the microanalysis（the energy spectroscopy, XRD and SEM）, the distribution size of particle of fly ash and cement paste intensity of various age for different grinding time were studied. The relationships of the activity and the composition of fly ash, microstructure and the distribution of particle size by mechanical activation of fly ash were obtained. The internal glass beads with activity were released by grinding fly ash for a certain time. The particle specific surface area was improved and the hydration reaction of the interface and the surface active center was increased by grinding. The granularity distributing of fly-ash trended towards optimization. The polar molecules or ions were easier to intrude into the internal cavity of the vitreous body. The active silica and alumina of fly ash were rapidly depolymerized. Each performance index of fly ash was increased before grinding for 20 min. Cement paste intensity of various age increased along with the grinding time, and the early strength increase range was big, but the later period intensity increase range hastened slightly. The internal part of vitreous of fly ash was destroyed if the fly ash continued to be ground and the activity of fly ash was reduced. It is suggested that Guozhuang＇s fly ash should be ground for 20 min.

Influencing factors of pyrite leaching in germ-free system

The effect of mineral particle size, pulp potential and category of oxidant on pyrite leaching was studied. The results show that a smaller mineral particle size leads to a higher leaching rate of pyrite, and the optimum result with pyrite leaching rate of 2.92% is obtained when mineral particle size is less than 0.037 mm. The pulp potential reflects the leaching process. The increase of pulp potential can improve pyrite leaching. The leaching rate and velocity of pyrite can be enhanced rapidly by adding strong oxidant. The kind and the method of adding oxidant have important effect on the pyrite leaching. Appropriate concentration of Fe3+ can enhance pyrite leaching but the precipitation generated by high concentration of ferric ion covers the surface of pyrites and prevents the leaching process. The leaching rate increases with the constant addition of H2O2.