In north Bayan Har gold metallogenic belt，one of the most important metallogenic belt in Central Orogenic Belt，is located in the Hoh Xil-Bayan Har late Indo-Chinese epoch orogenic belt.In this belt，the formation of late Paleozoic flysch-flyschschoid facies is the best developed sedimentary strata；late Triassic granitoids distribute along deep faults sporadically；NW-NWW trending faults developed extensively，which controlled the distribution of the intrusive rocks and the gold deposits.The microgranular disseminated gold deposit is the main type of gold deposits in this metallogenic belt，gold prospecting of this type has made some breakthrough recently，such as Dachang super large gold deposit has been found in recent years，and more prospecting achievement is expected.In this paper，by synthesizing the latest information from geology， geochemical prospecting and mineral deposits etc.，we build a GIS-based spatial database for the north Bayan Har metallogenic belt in Qinghai Province.Then a new regional exploration geological model of the microgranular disseminated type gold deposit（“Dachang” type） is established，in which the main prospecting symbols including the middle of the Trassic Bayan Har Group，the Trassic middle-acid intrusive rocks，NW-NWW striked linear structures，Au，As，Sb，Hg，Cu，Pb and Zn anomalies，Au-As-Hg-Sb-Cu and Sb-As-Hg combination anomalies，heavy concentrate anomalies of native gold，stibnite，cinnabar，realgar，orpiment， arsenopyrite， galena and sphalerite，placer gold mines，and the smallest prediction areas selecting from the prediction of potential gold resource in China.On such a basis，we established a suitable information quantity model of geological prospecting marks using the self-built and borrow model，combined with a study of the ore-controlling geological conditions and a summarization of metallogenic regularity.And the information anomalies mapping is finished in the study area according to the information computation method of Deposit Position Indicating System(DPIS).There are 38 prospecting area was delineated and evaluated，including 9 prospecting targets with level A，16 ones with level B and 13 ones with level C.And three key exploration areas，three fellow exploration areas and two reconnaissance areas are mapped out.Some new prospecting targets are delineated.
Jinshan gold deposit locates in Dazhuangzi-Jinshan-Xiaozhuang ductile brittle shear zone in north Qixia city，which is closely associated with basic vein rock in Mesozoic era.The fluid inclusions show that the ore-forming fluids are of low salinity and low-density NaCl-H2O-CO2 system characterized by rich CO2 in the early stage of mineralization.But after boiling action，it later becomes to be NaCl-H2O system formed at 2.33~3.00 km below the surface with a temperature of 165~280 ℃.Isotope studies show that the ore-forming fluids is mainly from magmatic water in the early stage of mineralization and much meteoric water were mixed into the ore forming system during the late stage，metallogenic materials originate from dikes of Mesozoic，and also from palanobasement of Jiaodong.Changes of Physical and chemical properties caused by boiling action and mixture of atmospheric precipitation is main metallogenic mechanism.
Bulansala gold copper deposit，located at the northwestern margin of the Junggar Basin，the southern margin of the Sawuer gold copper metallogenic belt.It was found that gold and copper metallogenic geologic condition was relatively superior.In order to find out the gold copper prospecting prospect，we applied geological mapping and pit engineering for exploration，32 gold copper vein and mineralized points were discovered，and it was estimated that the prospective resources of gold in the whole region is more than approximately 20 tons，and copper would reach up to more than 100 thousand tons，which belongs to large scale deposit.After the preliminary geological investigation，we considered genetic types of the ore deposit indicated the close relationship with convergent plate subduction island arc belt of tectonic altered rock type and quartz vein type gold deposits.It was pointed that NE-NEE fracture structure，granite diorite-porphyritic monzonitic granite contact zone as well as the eastern central volcanic institutions in the study area had a better ore-searching prospect.
In order to expand prospecting range at the Jinchang deposits，it is necessary to strength the comprehensive investigation and prospecting efforts in the deposits surrounding areas.According to previous research，it was believed that mineralized bodies in the Jinchang deposits was controlled by the granodiorite and diorite and the North-east，also the North-west and the nearly South-north trending fault.Through comparing the metallogenic element descriptive statistics，R-cluster analysis and factor analysis，it is found that the front halo and tail halo indicator elements in the mineral rights area belong to strong enrichment degree，and there are several stages of mineralization.By analogy the ore deposit，metallogenic model，metallogenic regularity，prospecting marks of Jinchang deposits，it is suggested the eastern and western region of the mine，and the contact region between Tianqiaoling Group，Tuopangou Group and Yanshanian granite porphyry intermediated-acidic Group，corcovadite，granodiorite porphyrite have greater prospecting potential.
Based on the study of fluid inclusion in gold-containing quartz vein of gold ore in Pingqiu，Jinping and its hydrogen and oxygen isotope composition，this thesis discusses property and source of ore-forming fluid. There are carbon dioxide gas-liquid two-phase and carbon dioxide gas-liquid three-phase based on the composition of fluid inclusion.The test data indicates that fluid inclusion in this area belongs to fluid in the medium and low temperature（159.5～351.8 ℃），low salinity （0.53%～16.71%）and low density（0.58～0.98 g/cm3）.The specific value of Na+/K+ in the fluid phase composition is less than 1，shows that this deposit has magmatic-hydrothermal character.Hydrogen and oxygen isotope composition: δD■is -49‰～-60‰，and δ18O■is 7.30‰～9.00‰.Cultellation in δD-δ18O diagram is distributed in the overrlap region of metamorphic and vivo.According to analysis by synthesis，ore-forming fluid of this gold ore may mainly include magmatic water mixed a lot of metamorphic water.Ore-forming fluid contained gold goes up along with shear zone and second level shear structure（host structure），settling in shear zone and fracture between interlaminations formed by anticline and shearing action，forming lenticular and layered quartz vein gold deposit.
Western Qinling Mountains is rich in gold resources，the area has a huge potential for prospecting.In order to investigate the mineralization extent of different ore-forming materilas，we analysis the fluid inclusion and stable isotope characteristics in the main mineralization stage of 19 main gold deposits from three metallogenic belts in Western Qinling Mountains，based on the results of previous studies.It was found that the metallogenic fluid of Western Qinling Mountain is a mixed origin consist by precipitation，metamorphic and magmatic water with characteristics low-pressure，low-temperature and low salinity，the ore-forming material is the mixed origin of magmatic and sedimentary rocks.From south to north，three metallogenic belts of Western Qinling Mountains have an obvious zonation features and it’s metallogenic fluid have a trend that shifting from mixed origin to deposit origin.
In order to solve the great difficulties in exploration with surface covered by the Quaternary and Neogene period at the Wangzulu ore block，three lines （line 188，196 and 204） was laid in the study area for anomaly delineationthrough introducing technology of controllable source audio-frequency magnetotelluric measurements.Combined with field geological survey，we interpreted the findings and roughly determined that the broken zone with gold presented a western trend until the Wangzulu ore block at the Zhaishang gold ore.It has been verified by drilling that No.9 and No.10 mineral vein of the Zhaishangore block almost extended to line 188 of the Wangzulu ore block.Additionally，quartz diorite bin vein was discovered in process of deep prospecting engineering，indicating that the ore-forming materials at the Wangzlu ore block mainly originated from the deep，and that showed the tremendous metallogenic potential.Practice demonstrated that，with the aid of controllable source audio frequency electromagnetic measurement for anomaly delineation，and with verification by deep drilling prospecting model in search of mineralized bodies，remarkable prospecting effect was obtained in the thickly-covered region of the western Qinling.
In order to predict the rock mass blastability classification more accurately，the evaluation model was established based on Principal Component Analysis and RBF Neural Network.Taking a mine rock mass for example，the four evaluation indexes（the rock mass density，compressive strength，tensile strength，the integrality index of rock mass） that affect the rock mass blastability were considered，and the sample data of 13 actual mine rock mass were counted.The sample data were processed by the method of principal component，the results were used as input factors of RBF network，and the level of rock mass blastability was used as output factor，the precision of rock mass blastability prediction can be more higher.The research results show that relative errors of predicting outcomes are all controlled within 5%，and compared with the prediction errors by BP neural network，the expected value relative errors of the four rock mass are reduced 71.94%，86.65%，73.20%，76.62%，respectively，the classification prediction accuracy are obviously improved.The model provides a better evaluation for the rock mass blastability classification analysis.
Due to the problems of low working efficiency，short cyclic footage，and high excavation cost of per meter roadway in traditional roadway excavation techniques such as air leg rock drill machine drilling and short hole blasting used in underground mines，in order to solve a series of mentioned issues，a new tunnel excavation technique，that is，medium length hole blasting technique of compound barrel straight cutting of equal diameter empty hole in tunnel excavating was well proposed in the present work.Meanwhile，corresponding blasting parameters of the technique were designed.Based on the YT-24 air leg rock drill machine drilling，short hole blasting，DF20-2BD drill jumbo drilling and short hole blasting，DF20-2BD drill jumbo drilling and medium length hole blasting，respectively，the field experiments of the specific mine were carried out under the condition of completing the same length （30 m） tunnel excavation.Some of data indicators were produced by three different methods.Namely，drilling and blasting such as drilling time consuming for each meter，drilling and blasting cost of per meter roadway and average cyclic footage were obtained in the experiments.The results showed that the developed technique can not only reduce the drilling and blasting cost，but also improved the average cyclic footage effectively by adopting DF20-2BD drill jumbo drilling and medium length hole blasting technique，which proved to be an efficiency and economical method of tunnel excavation.
The process mineralogy of polymetallic low-grade tailings of Liwu copper ore was investigated by chemical methods and microscopic observation.The results show that the major metallic minerals consist of pyrrhotite，chalcopyrite and marmatite.The major gangue minerals are quartz，chlorite，and plagioclase.The content of the coarse tailings of +0.097 mm is 63.2%，the copper content of the tailings of -0.200~0.074 mm is 57.12% of total copper，Znic content of the tailings of -0.200~+0.074 mm is 66.70% of total Znic.The distribution rates of the fine-disseminated gold and silver had a positive correlation with the distribution rate of copper.It was difficult for pyrrhotite，chalcopyrite and marmatite to liberate fully due to their complex intergrowth relationship.Compared to flotation，it is cost-effective that biohydrometallurgy is used to recover copper and znic from Liwu copper ore tailings.
In order to determine the proper stope structure parameters of room and pillar mining method in a phosphate rock Yunnan pravince，the limit span of stope were calculated in different depths using the mechanics analysis methods，and the stability analysis was conducted to determine the reasonable size of pillar. Research shows that，respectively，Terzaghi theory and equivalent weight of overburden rock hypothesis as the load on roof，under the mechanical theory the limit span of stope were obtained， according to the calculation results indicate：The Terzaghi theory only applicate to the shallow overburden pressure；When use the equivalent weight hypothesis as the roof load，elastic beam theory does not apply to deep ground pressure，each other in line with the actual mechanics theory，and the pillar stability analysis is used to determine the reasonable size of pillar.This study provide certain theoretical basis and reference for the theory and practical application of the optimization of stope structure parameters.
For improving the recovery efficiency of mining and increasing its productive capacity，the realization of the optimization of stope structure parameters requires following steps.Firstly，ANSYS software is adopted to carry out the numerical simulation analysis for the stope structural parameters of the twelve different mining programs，and then the relative targeted values are figured out，such as the maximum main stress of a stope，roof subsidence，sides displacement and maximum tension stress.After the careful analysis and selections，the following nine various feasible programs are finally selected out and each stope with the height of less than 14 m and the width of less than 15 m.Secondly，the orthogonal test range method （R Method） is carried out to take the significance analysis and calculation for the targeted values，which are obtained through the demonstrations of above programs，and finally we affirm that the optimal combination of the width and the height of the stope structure is respectively 9 m and 14 m.By applying the optimal stope structure into the field experiment，and taking the actual measurement for the roof subsidence of the stope，we come to obtain the maximum value with 19.91 mm，which makes the relative error of 7.48% comparing with the simulated results.Thus it shows and verifies the high accuracy of the simulated result.The finished stope experiment shows that if the optimal structural parameters by using the ANSYS-R method is carried out，which can not only ensures security and stability of the stope，but also can greatly improve the recovery efficiency and productive capacity of the stope.This method is also proved to be reasonable and reliable through the above experiment，and so that it can provide a decision-making basis for optimization of stope structure parameters design.
Due to the low production capacity of grinder，the grinding fineness can not reach the requirement of subsequent flotation，the poor result of flotation in Concentrating Mill of Jinchiling Gold Mine，Duan’s semi-theoretical formulate of ball diameter and the technology of accurate ball loading and addition were applied to calculate the initial ball scheme and extra ball scheme，besides，improve the grinding effect and flotation index by improving the site grinding process and increasing the mineral liberation degree.The industrial test results indicate that the adoption of accurate ball loading and addition method can bring a grinding mill production capacity increase by 5%~8%，grinding fineness of three ores increase by 7.16，14.03 and 12.13 percentage points respectively，electricity consumption decrease by 9.94%，11.47% and 10.14% respectively，unit consumption of grinding media decrease by 21.31%，15.84% and 17.83% respectively.Especially for the third ore，the degree of flotation tailings decrease by 35.29%，the recovery rate increase by 2.46 percentage points.The results indicated that the adoption of the technology of accurate ball loading and addition has bring a good production effect and a remarkable economic benefit，so it has a better using and popularizing value.
In order to retrieve gold resources from a quartz-vein type gold ore，the dressing tests using Knelson concentrator are conducted under the condition of coarse grinding.Based on the results of process mineralogy，the occurrence state of gold and disseminated features are analyzed.Combined with the production situation of serious loss in the gold tailings in the whole floatation process，the process of gravity-floatation joint technology mainly on Knelson concentrator is put forward to replace the previous whole floatation process.The results show that Knelson concentrator could recycle coarse free gold mineral when the gravity value is 60G，feeding speed is 3 kg/min，counterflush pressure is 0.04 MPa and fluidzed feeding volume is 3 kg/min.The obtained industrial test indexs show that compared with the single floatation technology，the gravity-floatation joint technology can lead to the increase of the recovery rate of gold by 19%.
In order to verify the feasibility of steel-fiber concrete superseding plain concrete in roadway support， the comparative analyses between these two kinds of support methods are performed from aspects of support theory，support effect and economic benefits.In theory，by analyzing strengthening mechanism of steel-fiber concrete and comparing the mechanical properties of them，this paper aims to analyze steel-fiber concrete’s adaptability to dynamic load.In support effect，field tests of the two support methods are conducted，aiming to investigate support effect in field and detect the roadway deformation.Economically，the economic factors in the process of drifting and supporting are analyzed comprehensively for the sake of economic evaluation.In conclusion，the research results show that the idea of steel-fiber concrete taking the place of plain concrete in roadway support is feasible in theory，reasonable in economy and reliable in safety.
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