Based on flotation research on a complex hard-processing oxide polymetallic silver ore in Gansu,the optimal flotation process is suitable for this ores.In process,gold and silver concentrate are optimally obtained with high effective mixed collector D-421 and high effective mixed frother Z-205,then lead concentrate is achieved by flotation with regulator Na2S,D-421 and Z-205.The recovery of Au and Ag can be greatly improved in the test.The production practice indicates that the technology conditions are reasonable with stable production indexes.

Starting with the six aspects such as formation temperature,formation water salinity,depositional rate,organic matter abundance and type,microbial population and shallow inhibition effect,this paper analyzes in detail each factor influencing the microbial activity,the growth and reproduction of methane bacteria and the generation of biogas of the Neogene-Quaternary in Hetao basin.It is revealed that the favorable layer of biogas source rock development lies to the upper and middle sections of the Pleistocene in Hetao basin.

The analysis of natural gas composition and carbon isotopes of methane confirms the existence of biogenic gas around the Tertiary Pliocene series and the Quaternary Pleistocene series in the Hetao basin. Detailed organic geochemistrcal data shows that the biogenic gas source rock of the middle and upper Pleistocene series in this area contains a high content of organic matters and typesⅡ2 and Ⅲ kerogens. The organic matter in the biogenic gas source rock is in low-mature stage, which is benefit for the formation of biogas. In addition, this article establishes a generation-evolution model of biogas, taking into account the region geology feature and temperature affection on the biogas generation, and puts forward that the best vertical extent for biogenic gas formation in the Hetao basin is in the middle of the Quaternary Pleistocene series, between 685 meters and 926 meters.

The exploration of biological gas in the Huhe Depression of the Hetao area has become the new domain of searching reserves while the exploration degree of biological gas is relatively low.According to the characteristics of seismic reflection such as amplitude,continuity,interior configurations and exterior shapes,three types of seismic facies are recognized on the seismic reflections of the Pleistocene in this area,including medium-intense amplitude continual paralleling or sub-paralleling sheet facies,variable amplitude weak-continuity and medium continuity and paralleling or sub-paralleling sheet facies,disorderly facies.Furthermore,the distribution map of seismic facies has been compiled for the Huhe Depression,and the sedimentary facies of wells He 1 and He 5 have been analyzed using the core data.In the end,the seismic facies have been transferred into sedimentary facies,and the results show that the shallow lake,semi-deep lake and shore lake sub-facies were mainly developed in the study area.It is no doubt that this research will have a guiding effect on the exploration of biological gas in this area.

Aim To explore the shallow gas about pleistocene and pliocene strata in Huhe Depression and research,the gas genetic type and accumulation geological faetors.Methods The composition of shallow gas and geo-chemical characteristics of source rock were tested.The samples of granularity was analyzed and the slice of drill core was identified as well.Results It has the geological conditions of biological gas reservoirs: organic matter abundance is high,gas generating capacity is good,Porosity and permeability is of superiority.Type of pore structure is mainly primary pore.The thickness of Glauber is salt,distributing widely and steadily,which can form favourable traps,ranged from 4 m to 34 m,and the main type of gas reservoirs belongs to alternate auto-storing gas derivation.Conclusion With the above research,it has indicated that the favourable exploration targets for shallow gas lies in ridgy areas relatively between two sub-depressions.

河套盆地呼和坳陷第四系、上新统气源岩厚1200m以上,有机碳平均含量0.59%,有机质类型为混合型及腐殖型,未成熟,处于生物化学生气阶段,具有大规模生气能力.大量水文浅井冒气泡,证实了生物气的存在.储层为浅湖、半深湖相粉细砂岩、泥质粉砂岩,成岩程度低,岩性疏松,孔隙度大于20%,储气能力强.第四系150～300m段发育泥岩及芒硝、腐殖土,具有较强的封盖能力,是比较理想的盖层段.生物气富集的主要控制因素为圈闭.通过类比,河套盆地成藏条件与柴达木盆地相似,资源潜力大,勘探前景好.