砂金

The eastern Laizhou Bay is an important potential area of littoral placer gold deposits of China, in Which both eluvial-deluvial and alluvial placer gold deposits are found. And placer gold anomaly is discovered in the littoral sand barrier, beach, subaqueous bar, subaqueous estuarine delta, seawater shallower than 14m, ancient lagoon, ancient alluvial layers and ancient coastline.

莱州湾东部是我国滨海砂金矿重要的成矿远景区，区内已探明有残坡积型和冲积型砂金矿床，并在滨海沙堤、沙滩、水下沙坝、水下三角洲、水深小于14m的浅海海域及古岸线、古泻湖、古冲积层中发现砂金异常，特别是海区的发现，为我国浅海砂金的调查开阔了新的前景。

Based on the Reserve Database of Mineral Resources in China (1997), this paper established the geological model, grade model, tonnage model and grade-tonnage model of 394 placer gold deposit s in China, which involve frequency histograms and cumulative frequency distributing graphs.

依据"1997年全国矿产储量数据库"资料，对全国 394个砂金矿床建立了地质模型、品位模型、吨位模型、吨位—品位联合模型，模型类型包括频率直方图、累积频率分布图；分别总结了砂金矿床品位及吨位分布的典型数学地质特征。

According to a couple of international seminars attended by the author of this paper and his on-the-spot investigation of alluvial gold fields at Yukon District of Canada in the year of 1989, an analysis and summary of the mining art and ore dressing of alluvial gold in Canada were made by the author himself.

根据1989年在国外期间参加的两次研讨会，以及对育空地区砂金产地的现场考察，归纳分析了加拿大砂金采选技术。200多座家庭式生产经营的中、小矿山，构成育空地区和全加拿大砂金产量的大部分。

The fingerprint features of placer gold has been a important method to seek primary gold.

砂金指纹特征是利用砂金寻找原生金的重要手段之一。

Gold placer deposits are controlled by drainage system land form and source of gold materials.They occur in the special Qat river terrace and Qtpu sandy conglomerate beds. Burial depth of the deposit is 5￣12m,with gold placer grade between 0 131 and

砂金矿受水系，中低山地形地貌格局和金物质来源的控制，赋存在特定的Qat河流阶地和Qtpu层位砂砾层中，层位稳定，矿床埋深5～12m，砂金品位0.131～0.235g／m3。

The northern part of the Greater and Lesser Xing'an mountains is located in Northeast China, where is abundant in gold placers.

大、小兴安岭北部位于我国东北，砂金资源丰富，采金历史悠久，出产&狗头金&，是国内外著名的砂金产地。

Besides, a few gold placers were formed in Early Pleistocene Epoch and Early-Middle Holocene Epoch.

现存砂金矿主要形成于晚更新世晚期，此外在早更新世及全新世早—中期也有少量砂金矿生成

For metallogenic environments, the neotectonic movement and climate are 2 most important factors. The neotectonic movement controlled the exposure, weathering and migration of primary provenance, the formation of valleys, the evolution of river systems and topography, and etc. The climate factor played important roles in the whole history of gold placers, especially in the formation of secondary provenance, the sorting and concentration of placer gold, the conservation and regeneration of gold placers, and etc.

在成矿环境方面，新构造运动对砂金矿的形成演化具有重要控制作用，主要表现在促使原生源暴露地表、风化、迁移，控制河谷的发育、水系与地貌的变迁等；气候因素贯穿于砂金成矿全过程，尤其在次生物源的形成、砂金的分选、富集、保存、&再生&等方面发挥重要作用。

The main primary provenance of placer gold are rock gold deposits. The tributary gold placers and weathering crust of free gold-bearing are prime secondary sources.

提出砂金成矿主要原生物源是岩金矿，次生物源中以含游离金的风化壳及支谷砂金矿为主。

In comparison on size, shape and quality of native gold between gold placer and original gold minerals, based on the study of native gold quality in the two types gold deposits and analysis on reproductive significance of gold placer mining areas, the preliminary discussion on hydrochemical mineralization factor of gold placer was made.

通过从砂金矿和原生金矿中自然金在粒度、形态、成色等方面特征对比，两类矿床中自然金成色的关系研究以及砂金过采区再生产意义的分析，对砂金水化学成矿因素进行了初步探讨。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。