Jiaodong gold ore-concentrating area is the third largest gold mining area in the world after the Lande gold mining area in South Africa and Muruntau gold mining area in Uzbekistan，and its proved gold resources exceed 4 500 t.Jiaodong gold ore-concentrating area formed in the Early Cretaceous tectonic regime transition period and has the characteristics of large-scale concentrated mineralization.This area is composed of a lot of super-large，large gold deposits and includes altered rock type，quartz vein type and interlayer fracture zone type gold deposit.The typical altered rock type gold deposits are Sanshandao，Jiaojia，Xincheng，Dayingezhuang，Xiadian and Dongfeng 171 deposits，and so on.The quartz vein type gold deposits include Linglong，Jinqingding and Denggezhuang deposits，and so on.The interlayer fracture zone type gold deposits are represented by the Pengjiakuang gold deposit.These gold deposits are mainly controlled by the regional faults，secondary faults and interlayer slide faults along the northern margin of the Laiyang basin.The gold deposits in Jiaodong mainly occur within the Mesozoic granite，minor whthin Jiaodong Group，Jingshan Group and Mesozoic strata.This paper selects the scientific problem of the source of ore-forming materials，and systematically analyzes the surface and deep-drilling samples sampled from the Jiaodong area by means of Au element geochemical analysis，in order to reveal the geochemical background characteristics of Au element in this area，and provides geochemical field constraints for discussing the metallogenic mechanism of high-intensity massive accumulation of Au element in this area.The results show that the average abundance of Au element (1.10×10-9) of the Jiaodong group is lower than that of Clark value of continental crust (1.21×10-9) and the value of continental crust of North China Platform，which shows the characteristic of gold deficit geochemical field.Moreover，the results also show that the gold geochemical background feild of the Jiaodong group is characterized by higher average Au abundance in the central area (1.35×10-9) and lower average Au abundance in the east and west of the Jiaodong area (0.95×10-9 and 0.76×10-9).The average abundance of Au element in the fresh rock samples of different rock types (Jiaodong Group,0.79×10-9；Mesozoic granites,0.77×10-9；Gabbro,0.63×10-9；Lamprophyre,0.93×10-9；Acidic dykes,0.82×10-9) from the deep drilling holes is lower than that of Clark value of continental crust and the value of continental crust of North China Platform，which also display the characteristic of gold geochemical deficit field.Therefore，there exists an Au element geochemical deficit field in the Jiaodong ore-concentrating area，combined with the evidence of hydrothermal activities in gold ore areas，we think the Jiaodong Group and the Mesozoic granite might partly provide the source of metallogenic materials for the formation of gold deposits in the Jiaodong area.
Rare metals are the key mineral resources of strategic emerging industries,which play an irreplaceable role in both the high-end equipment manufacturing industry and the field of new energy vehicles.In recent years, mineral geological survey work of lithium and other rare metal deposits have made breakthrough in West Kunlun，Xinjiang.Several lithium-beryllium and other rare metal ore deposits with large-scale and super-large prospecting prospets have been found.It is expected to become a lithium-beryllium emerging strategic mineral resources base in northwest and even the whole China.In Dahongliutan area，the main type of lithium-beryllium deposit is pegmatite-type.In view of many pegmatite type lithium-beryllium deposits，investigation and evaluation projects are being carried out，and good prospecting results are obtained.It shows that the potential of lithium-beryllium is huge in Dahongliutan area.However，there are few research reports on the resource potential analysis of pegmatite type lithium-beryllium deposits in this area.Therefore，the evaluation of the potential of mineral resources is helpful to find out the amount of lithium-beryllium resources in the study area，and provides the basis for systematic investigate.Based on the systematic data collection，field investigation and comprehensive research，this paper analyzed and evaluated the resource potential of pegmatite-type lithium-beryllium mineral in Dahongliutan area.The latest mineral resources potential evaluation method（geologic volumetric methods） was used in this study.Geologic volumetric methods is the average content of lithium beryllium mineral resources per unit volume of a typical deposit is extrapolated to the volume of the predicted area to estimate the amount of lithium beryllium mineral resources in the predicted area.And then，35 minimum prediction areas was circled，including 5 class A，8 class B and 22 class C.The resource reserves shallower than 350 m for Li2O and BeO were estimated to be 913.61×106 t and 27.18×106 t in Dahongliutan area.
Qimantage metallogenic belt is located in the western part of the East Kunlun Mountains.It is an important metallogenic belt in the western part of China.Superior metallogenic geological conditions have resulted in abundant mineral resources in this region.In recent years，a large number of mineral deposits related to intermediate-acid magmatic activities have been discovered in the Qimantage metallogenic belt.The genetic types of the deposits are mainly skarn，porphyry，high temperature hydrothermal，sedimentary metamorphic，sedimentary，hot water sedimentary-reformed and volcanic rock type.The minerals include copper，iron，lead，zinc and other metals.Tanbeixuefeng is a newly discovered tectonic altered type gold deposit in the region, which is located in the Qimantage back-arc rift basin，and the metallogenic geological conditions are very favorable.In this study，through 1∶10 000 soil geochemical survey in Tanbeixuefeng area，the results shows that Au is an important enriched element with a large coefficient of variation，indicating that there is superimposition of late stage mineralization.Moreover,R-type cluster analysis shows that Au and Bi are significantly positively correlated，indicating that Au mineralization may be related to mesothermal and low-temperature hydrothermal activities.Further analysis of geochemical characteristics of elements，combined with geological background，13 comprehensive soil anomalies dominated by gold have been delineated， trench prospecting has been carried out in AP7 and AP9 anomalous areas.A gold mineralization alteration zone has also been found，and three gold orebodies have been delineated in the zone.The gold orebodies are developed in the NW-trending structural fracture zone，as well as joint structure.The ore-hosting lithology is silicified altered rock and strong limonization.Several gold mineralization clues have been found on the surface，such as silicification，sericitization，and pyritization.Furthermore,based on the analysis of metallogenic geological conditions，the prospecting criteria of geology，geochemistry and structure are preliminarily established.Moreover，the genesis of the deposit is discussed and analyzed.Therefore，this study point out the prospecting direction in the Tanbeixuefeng area as follows：（1） The Au is already found in the No.1 mineralized alteration zone，thus the drilling should be carried out；（2） Compared the No.1 mineralized alteration zone，the prospecting should be focussed on the NWW fault；（3） Other unidentified Au high-value points in soil anomalies；（4） Other unchecked Au high-value points in soil anomalies，and Au and As combination anomalies should be strengthen prospecting work.It is a favorable area of prospecting for structural altered type gold deposits.Surface tracing and deep verification work in this area are expected to make breakthrough prospecting progress.
The greenstone belt around Victoria Lake in Northwest Tanzania is one of the famous gold metallogenic belts in the world，about 90% of the gold deposits are related to the BIF type gold deposits，but its overall research level is low，especially lack of researching on ore characteristics，gold-bearing properties，gold minerals and occurrence of gold，etc.Based on the study of ore characteristics and gold occurrence state of the greenstone belt gold deposit around Victoria Lake in Tanzania，the genesis of the deposit was comprehensively analyzed to guide ore processing and metallurgical process.By means of field observation，optical thin section identification，electron microscopy and electron probe analysis，the ore characteristics and occurrence of gold in PL7184 gold deposit have been systematically studied and analyzed.The results show that the PL7184 gold deposit belongs to altered rock type gold deposit controlled by ductile shear zone.It is a subclass of greenstone belt type gold deposit.Its gold orebodies mainly occur in shear fracture zone between banded iron-bearing formation rock and acid volcanic sedimentary rock.The gold ores are divided into four natural types in this area，they are dense disseminated pyrrhotite，sparse disseminated pyrrhotite，veinlet pyrrhotitand star-bearing point pyrrhotite.Among them，the dense disseminated gold pyrrhotite ore has the richest gold content，accompanied by strong pyrrhotitization，silicification and arsenopyrite alteration.The primary ore mineral symbiotic assemblages in this area are mainly silver-gold deposit+natural gold（small amount）+pyrite+quartz+chlorite+arsenopyrite+pyrrhotite.Some of the marenatural gold+pyrite+quartz+chlorite，natural gold（small amount）+pyrite+quartz.The content of Au in gold minerals is 65.63% to 85.36%，with an average of 74.77%.The content of Ag is 12.25% to 33.79%，with an average of 24.27%.The ratio of w(Ag)/w(Au) is 0.14 to 0.51，mainly concentrated in 0.25 to 0.34.The main types are silver-gold deposits，with a small amount of natural gold.The fineness of silver-gold deposits is 656.3‰ to 791.8‰，with an average of 734.5‰，and the fineness of natural gold is relatively high，the highest is 853.6‰.The occurrence of gold minerals is mainly intergranular gold，followed by encapsulated gold and fissure gold.Meanwhile，the particle size of gold minerals is mainly medium-fine grains，and the particle size is 0.01 mm to 0.07 mm in more.
The exploitation of mineral resources is accompanied by the destruction of ecological environment.For a long time，based on the idea of green mining industry，many scholars have conducted researches on green mine and green mining，therefore，a large number of technical materials and evaluation data are accumulated.In order to achieve the goal of high-efficiency，waste-free，harmless and ecological mining，Sanshandao gold mine has been continuously exploring and promoting green mining，and a series of green mining technologies have been innovated and excavated.However，there are no precedents and theoretical guidance in the early application of relevant technologies，and the investment problems of long cycle and high cost are faced，so it is particularly necessary to carry out the priority analysis of technology application.Based on the geological conditions of the mining area and the existing technological innovation achievements，the green mining technology system of Sanshandao gold mine was established，which is mainly composed of four key technologies and eight innovative technologies.On this basis，an optimized model of grey correlation analysis was put forward to evaluate and analyze green mining technology.Firstly，a hierarchical evaluation index system of green mining technology of target layer，criterion layer and index layer was constructed to systematically reflect the influence of various factors on green mining technology，and eight innovative technologies of Sanshandao gold mine were selected as evaluation objects.Then the combination weighting of AHP and entropy weight method was used to make up for the deficiency of subjective and objective weighting method，which makes the process of weighting tends to be reasonable.Finally the green degree of Sanshandao green mining technology was quantitatively analyzed by using the optimized model of three weighting methods and the traditional equal-weighting model，by comparing and analyzing the results of correlation degree of four models and ranking eight green mining technologies，the priority of green mining technologies of sanshandao gold mine was obtained.The results show that，among the evaluation indexes，the weight of personnel operation safety，mechanical and intelligent degree and the level of resource recovery and utilization is relatively large to green mining technologies.Among the technologies，the application of trackless intelligent equipment has the highest priority and contributes the most to the goal of green mining.This result indicates that the direction of technological innovation of Sanshandao gold mine should focus on realizing mechanical and intelligent mining.This result is helpful in guiding the work of decision-making department，realizing the ordering of green mining and reduce the cost of investmentt in Sanshandao gold mine.
The mining of gently inclined thin veins always has the problem of low production capacity and difficulty in mining.It is still inconclusive as to which mining method is more suitable for the mining of such ore bodies.The choice of mining methods is closely related to the economic benefits，production scale，safety recovery and resource recovery rate of the mine.Therefore，the preferred research of mining methods is particularly important.In order to solve the problem of optimizing mining methods for high-quality gently inclined thin veins，a comprehensive evaluation standard system combining variable weight analysis and TOPSIS was proposed to comprehensively evaluate various mining methods.Firstly，a comprehensive evaluation index system was established，taking factors such as mining cost，ore recovery rate，ore depletion rate，difficulty in controlling ground pressure，stability of stope，mining ratio of thousand tons，suitability of the project，difficulty in construction，field production capacity as considerations.Considering the constant power determined by conventional methods such as AHP，there may be a phenomenon of “state imbalance” when evaluating each candidate scheme，introducing a variable weight theory and appropriately adjusting its weight to ensure the balance of various factors.Then the superiority of each scheme was obtained by using TOPSIS method to approach the ranking method of ideal solution.Finally，taking the optimum selection of mining methods in a mine in Inner Mongolia as an example，four schemes were put forward，which were the two-step strip and close filling mining method （Scheme Ⅰ），the upward horizontal layered filling mining method for scraper mining （Scheme Ⅱ），the upward horizontal layered filling mining method for electric picking （Scheme Ⅲ） and the room and pillar mining method （Scheme Ⅳ）.The results show that the superiority of each scheme is 82.5%，32.8%，55.3% and 53.8%，respectively.Obviously the first scheme is the best one.The results are consistent with the engineering practice，which shows that the research idea has reference value for the optimization of mining methods，and provides a scientific and effective analysis method for the optimization of mining methods in future engineering.
In the numerical analysis of mine geotechnical engineering，it is of practical significance to study the construction method of 3D numerical model of complex cavities for the treatment of cavities.The pre-processing ability of geotechnical engineering simulation software is poor，and the current modeling method can’t well build complex geological body numerical model，and cannot fine divide the grid，resulting in the difficulty and work intensity of geotechnical engineering researchers in the early stage of modeling.In order to accurately analyze the law of surrounding rock movement and stress change of underground engineering, especially the stability of complex goaf formed by different mining methods and the stress change of ore pillar，the paper proposed and improved the 3DMine-surfer-rhino-ANSYS-FLAC3D multi-software joint modeling method.The method can solve the problems of 3D numerical model construction of complex goaf group and mesh generation of large number and small size ore pillars.The paper also described the specific modeling steps.The complex cavity group model constructed is closer to the reality，including the undulating form of surface DEM and more refined mesh of cavity and pillar model. At the same time，the total number of model grid elements is reduced，and the grid size of local key research areas can be adjusted according to the needs，so as to improve the accuracy of the calculation of key areas and accurately describe the stress change of ore pillars.This modeling method can be used to flexibly control the sequence excavation of different layers，stages and chambers of the layered ore bodies，and can be used to simulate the production sequence according to the engineering design at the early stage or the actual engineering production sequence at the later stage，so as to find a safe and reasonable mining production plan.A three-dimensional numerical model of goaf formed by shrinkage stoping method and chamber and pillar method was established by taking the mining of manganese ore body in Daxin mine of Guangxi as an example. Research results show that：（1） The Daxin manganese ore of shrinkage stoping method in mining area，empty part of the needle deformation is large，there are risks caving，the surface subsidence deformation is high;（2） The method of room and pillar mining zone，part of the pillar plastic failure，the surface subsidence deformation amount is larger;（3） Method of shrinkage stoping with cemented filling empty area：Fill in the blanks by stage filling area，after filling in the fourth stage，the surface settlement decreased significantly.In the vertical and vertical consolidation filling scheme，after filling one ore chamber with two ore chambers，the surface subsidence is smaller than that before filling，and the area with large subsidence becomes discontinuous. In the scheme of filling one ore chamber with another ore chamber，the surface subsidence deformation is one order of magnitude lower than the former two schemes，and the area of deformation area decreases and the continuity decreases.Among the three filling schemes，the one-filling and one-filling schemes have better governance effect，and the surface is more stable at the initial stage of governance.
The in-situ stress is the fundamental force causing damage and deformation of underground rock engineering.With the continuous increase of the mining depth，the ground pressure disaster of the mining area has gradually increased under the action of deep high ground stress.A large number of untreated goaf have been formed in the exploration and mining operations of the old and new areas of the Lanniping copper mine. Due to the influence of ground pressure，a number of collapse pits have been formed on the surface.In order to continue the safe and reasonable production work in the mining area，it is necessary to accurately measure the distribution of ground stress in the area and to optimize the layout of the roadway.The three-dimensional in-situ stress test was carried out on the three middle sections of the deep Lanniping copper mine by the stress relief method，9 sets of testing data in vertical direction are obtained.Meanwhile，the confining pressure rate test was carried out on the core sample，and the working state of 12 stress sheets was determined，and the distribution characteristics of the three-dimensional stress field were analyzed.The measurement results show that maximum principal stress，intermediate principal stress and minimum principal stress show an increasing trend with the increases of depth.The maximum principal stress values of the three measuring points in this test result are all high，the minimum value is 2 350 m，which is 28.62 MPa，and the maximum value is 1 900 m，about 43.1 MPa.According to domestic and international experience，the original rock stress field in the Lanniping belongs to the high geostress state.Combined with the layout of the stope and the specific mining method，the corresponding ground pressure testing measures and reasonable support methods should be adopted to ensure the safe mining of the mine.The original rock stress field is dominated by horizontal tectonic stress.The overall performance is NNW-SSW. According to the maximum shear stress theory，when the vertical stress at the top of the roadway and the vertical stress at the sidewall of the roadway are greatly different，the roadway layout should follow the formula of equal-stress axial ratio （i.e.，roadway gang width/roadway gang height = vertical stress at the sidewall of the roadway/vertical stress at the top of roadway），and then the roadway should be most stable.With the measurement results applied to maximum shear stress theory，the roadway layout is optimized，and a three-dimensional geological model is built within which the stability of the roadway is analyzed.Through analysis and comparison，it is found that the stress，displacement characteristics and plastic zone distribution of the surrounding rock in the rearranged roadway are superior to the original roadway.Therefore，the section size and stress distribution of the roadway should be considered to determine the optimal arrangement of the roadway in the actual engineering.The measurement results have important guiding significance for mine support design and safe production.
The evaluation of human-machine efficiency in plateau mines is one of the important issues related to high-efficiency mining at high-altitude.Compared with the plain area，it is more complex.The mining industry at home and abroad rarely develops the ergonomics of high altitude and cold or special and extremely difficult environments.The high-altitude，low-pressure，low-oxygen，low-temperature environment not only causes a significant reduction in personnel fatigue tolerance，but also negatively affects the ability and efficiency of personnel to operate equipment，and produces correlation feedback with complex production factors such as multiple types of work and continuous labor in mines.It has a superimposed effect on the decline of human-computer efficiency.Taking a copper polymetallic mine in Tibet as the research object，this paper investigated and analyzed the influencing factors of human-machine effectiveness of plateau mines and scores made by experts.From the three aspects of human factors，equipment factors and environmental factors，17 evaluation indicators were established and a comprehensive evaluation index system suitable for high-altitude mines was constructed. The weight of each index was determined by analytic hierarchy process，so as to clarify the weight of each influential factor index in each level and the whole.The multi-level fuzzy comprehensive evaluation method was used to construct the judgment matrix.The weight vector and the integrated fuzzy matrix were established to obtain the system membership vector.The evaluation results of the mine indicate that the ergonomic evaluation level of the mine is “medium”.The analysis of the evaluation results shows that the oxygen pressure in the environmental factors is low，which has a great impact on the physical condition of the employees and the operating state of the equipment.To improve the human-machine efficiency of the mine，the working environment at the construction site should be improved.Based on the analysis of human-machine effectiveness and the characteristics of high-altitude mines，this paper establishes an evaluation index system for human-machine effectiveness of plateau mines.The comprehensive scientific nature of evaluation was fully considered when setting indicators.The evaluation index system was weighted and the evaluation model was constructed.In order to reduce the influence of subjectivity on the evaluation results of human-machince effectiveness in AHP method，the analytic hierarchy process and fuzzy comprehensive evaluation method were combined to evaluate the human-machine effectiveness of plateau mine.The method has the characteristics of rationality，objectivity and scientificity to avoid artificial error.This model can provide an effective tool for the evaluation of the plateau mine management，provide support for the optimization of production organization in high-altitude and high-altitude mines，and provide a scientific basis for formulating reasonable countermeasures to improve human-effects.It has certain theoretical significance and practical value.It provides a certain reference for similar plateau construction problems.
The accurate evaluation of the classification of rock mass blast ability is of great significance to the design of blasting excavation and the safety and stability of geotechnical engineering.At present，scholars at home and abroad in the field of blasting have not reached a consensus on the evaluation method of rock blast ability.The factors affecting rock blasting are very complex，and the research indicators adopted by different scholars are different.By comprehensively considering the influence of the inherent properties of the rock mass and the actual blasting effect on the rock mass blast ability，six kinds of attributes including acoustic wave and wave impedance of rock mass，volume of blasting funnel，percentage of large blocks，percentage of small blocks and average eligibility rate were selected to predict the classification of rock mass blast ability.Considering the complex and varied geological conditions of engineering rock masses，according to the actual situation of several mines，55 sample data were selected，which cover quartzite，magnetite，skarn，diorite, gneiss,the lithology of marble，granite，limestone，metamorphic schist，dolomite，sandstone，etc..The sample raw data are from many rock mass engineering with different geographical locations and different geological conditions，which are representative.The PCA-SVM model and the SVM model were used to compare and analyze the explosive rock prediction results.Firstly，the same random seeds were used to ensure that the number of ore samples of the two models is the same as that of the training set and forecast set.Then，according to the data extracted by the principal component analysis and the raw data that have not been processed，the SVM models were established respectively，and the 11 prediction results were compared and analyzed.In the 11 randomized trials，the accuracy of PCA-SVM model was 100% at one time，there were 8 cases where one sample was misjudged,and 2 cases where two samples were misjudged.The number of misjudgments in the PCA-SVM model in a single random experiment is less than or equal to the SVM model.The average prediction accuracy of the PCA-SVM model is 90.1%，which was significantly higher than the SVM model.The results show that：（1） The prediction model based on principal component analysis and support vector machine eliminates the information overlap between the impact indicators and extracts four principal components which contain 98.38% of the original information.Compared with the standard SVM model，the PCA-SVM model not only reduces the dimension of the data，but also improves the accuracy of the rock explode grade from 78.5% to 90.1%.（2） The prediction results of PCA-SVM model are in good agreement with the actual situation.A small number of misjudgments mainly occur between some rock samples with small differences in characteristics.（3）The PCA-SVM prediction model based on the stratified random sampling technique ensures the randomness and difference of the sample data between the training set and the test set.This method is more scientific and reasonable than the general research model，and has a certain reference significance for the research of similar engineering.
With the extension of mining to the deep，the harsh mining environment of “three high and one flexible” is becoming increasingly prominent，among which the high temperature thermal hazard is a complex problem.In the process of mine production，under the influence of high temperature and heat environment，the air flow in mine roadway exchanges moisture and heat in high temperature and heat environment，which makes the air flow temperature rise，and then induces a series of problems，which eventually lead to a series of problems，such as difficulty in ventilation management，decline of production capacity，deterioration of working environment and so on.Because of the large depth of the mine，it is more difficult to ventilate and cool down the mine.During the period of mine ventilation，air flow is discharged from the surface along the shaft，roadway to the working face and through the return air shaft.During the above process，the air flow exchanges greatly with the mine environment in the shaft，roadway and working face，and the nature of air flow changes accordingly. Exploring the temperature variation characteristics of air flow in three stages of shaft，roadway and working face is helpful to determine the appropriate mining depth and choose the appropriate cooling mode. For deep mines，it is difficult to meet the need of deep mining only by using ventilation cooling technology.Reveal romantic from the perspective of thermodynamics in the heat exchange law ventilation circuit principle of finite difference method was used to calculate deep wellbore temperature，and in this roadway and the working temperature change trend was deduced，combined with the mine safety production permit back-stepping，temperature eventually acquire ventilation cooling recoverable under the condition of the limit depth formula.Guangxi copper mine zinc polymetallic ore body was sellected as engineering application test area，to analyzed the formula.The results show that the heat exchange model based on airflow can deduce the calculation formula of airflow temperature in wellbore，roadway and working face.Assuming that the working face temperature reaches the maximum allowable temperature for safe mining，the mining limit depth and the ventilation limit length of the roadway under this condition can be deduced reversely （when ventilation and cooling measures are adopted only）.Based on the actual conditions of the zinc polymetallic ore in the Tong-keng mining area，relevant data are brought in to verify that the calculated limit mining depth is in line with the reality，that is，the derived formula is feasible.
The technology of unclassified tailings high concentration backfilling has been applied to underground mining gradually.Because it has many advantages such as environmental protection，less dehydration，dispose more tailings.The grain size of tailings are getting smaller and smaller with the progress of beneficiation technology. This situation leads to the result of tailings concentration is unsatisfactory. Aiming at the difficulty of concentrating the super fine tailings of a lead-zinc mine in Jiangxi，this study explored the feasibility of adding flocculant to improve its concentration effect.On the basis of physical and chemical properties analysis for solid-liquid two phase coupling respectively under the condition of static and dynamic flocculation settlement of orthogonal test，we determine the tail slurry flocculating settling velocity in the enrichment，and by using the MATLAB software carry on the regression analysis of experimental data for the selection and dosage of flocculant，which provides the basis for the determination of optimal concentration of diluted slurry.Firstly，varieties and dosage of flocculants were determined through static natural settlement tests.Secondly，dynamic flocculation settling tests were conducted according to the varieties and dosage of flocculants that determined before.The influence of feeding speed to the clarity degree of overflow water and the underflow concentration were tested.The experimental results show that the feeding speed by 0.89 t/(m2·h) reduced to 0.60 t/(m2·h)，overflow water solid content gradually decreased，when the feed concentration 13.59%，the concentration of the AH-910-SH type flocculant is 20 g/t，the feeding speed is 0.60 t/(m2·h)，the underflow concentration reached a maximum of 72.82%，the overflow water solid content is 162.68×10-6 （<300×10-6），the superfine all backfilling flocculation sedimentation effect is best.This test provided theoretical basis to the rapid settlement technology of ultra-fine unclassified tailings.Thus，the test established the technical foundation of high concentration backfilling of ultra-fine unclassified tailings.The results of the study have certain significance for the application of continuous settlement technology of unclassified tailings.
Tailings reservoir is an important facility to store tailings, and it is a dangerous source with high potential energy, there is a risk of dam break.Once the tailings reservoir is crashed, it will seriously affect the safety of people’s lives and property and destroy the local ecological environment, so it is of great significance to evaluate and predict the safety of tailings reservoir. For the tailings pond is a nonlinear complex system, there are many uncertain factors in the process of safety evaluation and prediction of tailing pond, and the factors are interrelated and coupled, so the safety evaluation of tailing pond has uncertainty.In order to accurately evaluate the safety level of the tailings pond，the Huangjindong tailings reservoir was used as a sample，and the relationship between various factors in the safety of the tailings pond was analyzed.Comprehensive application of fuzzy multi-connection theory and analytic hierarchy process (AHP)，a comprehensive safety assessment model for tailings pond with five influencing factors and 26 influencing factors was constructed.The weighting coefficient of each subjective and objective index was obtained by AHP，and the evaluation index was graded. In order to quantify some qualitative factors，the fuzzy multi-connection degree theory was introduced to identify the uncertain factors affecting the safety of the tailings pond.The combination of certainty and uncertainty was considered to deal with the comprehensive integration problem, and the measured values of quantitative indicators of membership function were constructed.The results show that the comprehensive safety evaluation score of the Huangjindong tailings pond is 80.052，and its safety grade of the golden hole tailings pond is Ⅱ，and the tailings pond was in a relatively stable state.By calculating the degree of contact between the first-level indicators，the degree of opposition c is 0.0615，the degree of identity a is 0.5633，a>c，set pair potential is the same potential，and the investment and management of safe production should be strengthened.Using the five-element relationship function to calculate the uncertainty of five influencing factors，through calculation，safety management（B1），tailings dam（B2），tailings discharge（B3），flood discharge system （B4） and tailings transport and return water（B5），the uncertainty of the five indicators is 0.4013，0.4240，0.5132，0.0148 and 0.2644. By comparing the size of the uncertainty factor，tailings discharge（B3）>tailings dam（B2）>safety management（B1）tailings transport and return water（B5）>flood discharge system（B4）.In the end，tailings discharge is the most uncertain factor，and it is necessary to strengthen the management of tailings discharge.The evaluation results obtained by the model are consistent with the actual results，which provided a feasible method for the safety evaluation of the tailings pond.
The total amount of gold produced in China is among the highest in the world，and the massive mining of gold has led to a large accumulation of gold mine tailings.There are a lot of toxic and harmful heavy metals in gold mine tailings.How to deal with gold mine tailings in a safe and environmentally friendly way is a very intractable problem at present.Recycling gold mine tailings as cemented paste backfill（CPB） filling into the mine as support is currently a popular method to solve the problem.In order to explore the compressive strength and environmental effects of gold mine tailings after being recycled as CPB，the cementing ratio test，heavy metal leaching and solidification test of gold tailings was carried out.In the cementing ratio test，12 groups of samples were prepared，the cement-tailings ratio was 1∶6，1∶8，1∶12，1∶20，and the mass concentration was 77%，75%，73%.After a period of maintenance，the uniaxial compressive strength for 7 days，12 days and 28 days of 12 sets of test pieces were tested respectively.Finally，the optimum cementing ratio parameters were determined on the premise of considering the strength requirements of mining technology support and the economic cost of filling comprehensively.Heavy metal leaching test was carried out in two groups：48 hours leaching test of filling slurry and dynamic leaching test of CPB.The two sets of experiments were used to simulate the short-term leaching of the filled slurry and the long-term leaching of the CPB，and the purpose was to explore the environmental effects and potential pollution elements of the gold mine tailings after being recycled as CPB.After the heavy metal elements with potential contamination risks are identified by the leaching test，the corresponding curing agent was selected to carry out the curing test of heavy metals.The leaching of potentially polluting elements was tested again by adding different concentration of solidifying agent，and the concentration of solidifying agent which could eliminate the pollution risk of heavy metals leaching from CPB to groundwater was finally determined.Based on the above experiments，a safe and environmentally friendly method for recovering gold tailings is finally determined.The results show that The optimum cementation ratio of the gold tailings is 1∶8 for the cement-tailings ratio and 75% for the mass concentration.The leaching of harmful elements in the tailings can be effectively controlled after the gold tailings are recovered as CPB，which reduces the pollution to the environment.The As leached from CPB has potential pollution risk to groundwater，adding 3% FeCl3 to CPB can effectively avoid the pollution.
With the development of safety science，the scope of safety science research is not limited to accident prevention and risk control.The goal of safety management has gradually changed to the pursuit of coordinated operation of the whole system and the protection of people’s physical and mental well-being.And there are still frequent mine accidents and serious safety situation in China.In order to make the safety management of underground metal mines not only limited to accident prevention and hidden danger control，but also to make safety management better protect workers’ health and coordinate the operation of production system，combining with the generalized safety model，a safety management model of an underground metal mine was constructed，and the meanings and correlations of all levels of systems and elements in the model were described.In order to realize the information communication of all levels of systems in the generalized safety model，a method considering the fuzziness and uncertainty of evaluation data was proposed by using cloud model，AHP method and CRITIC method.It can also adjust the weight of each part by itself.Using cloud model to unify expert opinions and consider the fuzziness and uncertainty of evaluation data，AHP method to consider the subjective weight，CRITIC method to measure the objective weight and modify the subjective weight.The production system of an underground metal mine was divided into 12 microsystems，such as man-lifting system，etc.The weight of each microsystem was obtained after modification，and the safety assessment grade clouds of the mine and the microsystems were made.The results of evaluation examples show that the mine is in a safe state and the safety situation is stable，but it is necessary to make decision and deal with these problems，such as the low mean value of safety evaluation score of M2，M7 and M8 microsystems，the great fluctuation of safety score of M9 microsystems，and the low mean value and great fluctuation of safety score of M10 and M11 microsystems.Moreover，the weights of M2，M9，M10 and M12 microsystems after modification are relatively high，so we should pay attention to their safety management.The generalized safety model is no longer confined to accident prevention and risk control，aiming at ensuring the coordinated and efficient operation of the crowd and the machine group.It can better monitor the safety situation of the mine，protect the health of the workers and make the whole production system of the mine operate safely and efficiently.The evaluation method proposed in this paper is helpful to obtain the safety information of each system in the generalized safety model，and to obtain the evaluation results reflecting the fluctuation of mine safety situation considering the subjective and objective weights.
In recent years，the common problems faced by non-ferrous metal mining enterprises are overcapacity，declining prices and unstable operating environment.These directly lead to greater financial risks.Some enterprises are on the verge of bankruptcy.Cash flow is the blood of enterprise development.Therefore，it is very important to make an early warning study on the cash flow problems of the operation activities，investment activities and financing activities based on the characteristics of operation of non-ferrous metal mining enterprises.Analyzing the dynamic balance of cash flow in terms of quantity，time，and structure ratio，and standardizing the operating procedures such as time，mode，cash inflows or outflows，it can prevent financial risks and play a proactive role.This paper analyzed the cash flow influencing factors of business activities，investment activities and financing activities.Selected six horizontal variables including the net cash flow of operating activities，investment activities and financing activities，retained profits，provident fund and cash.Selected 10 flow rate variables such as operating inflow and business outflow，and 49 other auxiliary variables.The enterprise cash flow early warning model was constructed by using the system dynamics modeling software Vensim-PLE，and the main mathematical equations of the model variables were given.Taking a copper mining enterprise for further application.Statistical methods，early warning techniques and mathematical methods were used to estimate the model parameters based on the investigated enterprise data and the industry regulations.The main constant parameters were set，the sensitive factors were selected for simulation operation.Taking 2017 as the initial point of simulation，the simulation period is 2018 to 2022.The simulation results show that the annual mineral output of the enterprise increases，and the amount of concentrate also increases，and the operating inflow will change with the price fluctuations.Net cash flows from operating activities declined in 2019，2021 and 2022.The environmental investment and total outflow of investment is tilted upwards，the increase in untreated waste is significantly reduced，and the curve is tilted downwards.Investment inflows are smaller than investment outflows，it lead to a downward trend in net cash flow from investments.After the increase of investment outflow，the capital pressure has increased.Under the lack of own funds，the financing demand has increased，which has caused the increase of financing inflow，and the net cash flow for financing has tended to increase.The simulation results are consistent with the actual results，which shows that the cash flow warning model built in this paper has a good applicability.This paper suggests in general that the investment decision should collect the detailed data information as far as possible，forecast the future cash flow trend，know the cash balance situation in a timely manner，do a good job in advance to cope with the shortage of funds，improve the profitability of funds.In business activities，when the net cash flow is negative，it is necessary to reduce production costs and give priority to mining rich mines.When the net cash flow is negative in the productive investment activities，we need to do a good job in the optimization and raise funds in advance.In fund-raising activities，it should pay attention to the financing method and cost in order to control the funding time and avoid the risks arising from the collapse of the funding chain.
Zhenyuan gold deposit belongs to fine disseminated gold deposits located in Ailao Mountain.This type of gold ore is often associated with sulfide and carbon，which could diminish the gold cyanidation leaching efficiency and reduce the gold recovery efficiency in the next step.In order to guarantee the recovery rate of gold,the process mineralogy has to be proceeded to ensure the gold wasn’t been wasted due to the improper process.X-ray diffraction，X-ray fluorescence，Energy Dispersive X-Ray Spectroscopy，particle size test and mineral liberation analysis have been used to determine the chemical composition，mineral composition，particle size and the characteristic of Zhenyuan refractory gold ore obtained from Zhenyuan gold deposit.The X-ray diffraction，X-ray fluorescence，Energy Dispersive X-Ray Spectroscopy and mineral liberation analysis（MLA） shows that the main phase of the concentrate is sulfide（32.37% of pyrite，0.58% of stibnite and 0.46% of arsenopyrite），carbonate，silicate and the chemical component of concentrate is mainly iron（10.86%），sulfur（12.48%），silicon（18.56%）.Meanwhile 0.87% of arsenic and 5.55% of carbon（3.18% organic carbon and 2.37% inorganic carbon） have been found from the sample，which is harmful to cyanidation process. The particle size，encapsulation and exposure of pyrite，stibnite and arsenopyrite were analyzed with particle size test and MLA test. The particle size of sulfide is mainly between 10~75 μm，about 90%.A large number of sulfide is fully encapsulated（83.6%），only few of them are totally covered with gangue（0.9%）.Gold diagnostic leaching and MLA test were carried out to determine the occurrence state of gold.Sodium cyanide，acetonitrile，nitric acid and fire-assaying method has been used to determine the gold chemical content in native gold，sulfide，carbon and silicate.The gold diagnostic leaching result shows that 96.16% of gold is covered with sulfide and few is in the form of native gold or covered with silicate and carbonate.No gold is wrapped in carbon.MLA test could automatically diagnose different phase of gold ore based on electron software，energy spectrum and MLA software.It also could built standard data base of sample ore and calculate the process mineralogy data automatically.From the MLA test，the electron microscopy （SEM） images of sulfide and native gold has been collected and analyzed，which shows the similar result with gold diagnostic test that most of the gold is wrapped in sulfide. According to the mineralogy process which have proceeded，this gold concentrate is a carbon-baring sulfide gold ore.Since most of the gold is fully covered with sulfide，the sulfide removing process is becoming necessary.It is recommended that oxidation or grinding process should be proceeded before gold leaching process.
Refractory gold ore is a kind of gold ore which can not be effectively extracted by conventional cyanidation process after fine grinding.High-sulfur ore is the most common refractory gold deposit in China.Refractory gold concentrate is an enrichment of gold grades greater than 10×10-6 obtained by fine grinding re-election or flotation of refractory gold ore.In view of the complex mineral composition of refractory gold concentrate with high sulphur content and the characteristics that gold is often encapsulated in other minerals，the process mineralogy of a gold concentrate in Longnan Zijin was studied by means of multielement analysis，X-ray diffraction，mineral dissociation analysis and scanning electron microscopy.The mineral composition，the occurrence state of various phases and the associated law of gold were thoroughly analyzed，to provide theoretical basis for the selection of gold extraction process for gold concentrates.The results show that the S and As contents of the gold concentrate are 42.12% and 2.31% respectively，and the proportion of gold encapsulated by sulfide is 56.19%.The gold concentrate belongs to the refractory gold deposit encapsulated by sulfide.The main gangue in the gold concentrate are quartz and sericite.The main metal minerals in the gold concentrate are natural gold，silver-gold ore，pyrite and arsenopyrite，of which pyrite accounts for 79.6% and is the main carrier of gold minerals.The content of pyrite and arsenopyrite increased from 63.83% and 1.77% to 82.95% and 4.85% respectively，while the content of quartz and sericite decreased from 23.57% and 8.37% to 5.91% and 4.97%，respectively，when the particle size of the gold concentrate decreased from +0.075 mm to -0.045 mm.The size of gold minerals ranges from 1 to 10 microns，the Au content in gold minerals is 74% to 89%，the Ag content is 9% to 23%，and the Fe content is 1% to 9%.The main gold minerals are silver and gold deposits，accounting for 86.67%.In addition，there are a small amount of natural gold，accounting for 13.33%.The liberation degree of gold minerals is 30%.The encapsulated gold minerals are associated with pyrite，which is semi-encapsulated or completely encapsulated，and the encapsulated gold often occurs in the pores of pyrite grains.The degree of monomer dissociation of gold minerals increases with the decrease of sample size.That is，the regrinding of concentrate is beneficial to the exposure of gold particles，making gold particles fully contact the leaching solution，thus improving the leaching rate of gold.
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