Metal Mine

Development History and Basic Categories of Mine Backfill Technology

LIU Lang, FANG Zhiyu, ZHANG Bo, WANG Mei, QIU Huafu, ZHANG Xiaoyan

2021, 50(03): 1-10.

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Cemented paste backfill （CPB） is an important technology carrier to realize the green development of mining， which has made great progress in decades of mining practice. On the basis of summarizing the development process and basic categories of conventional CPB， the paper puts forward the coordinated development goals of CPB， solid waste disposal， goaf reuse， geothermal development， strategic resource reserve and intelligent control， and takes CPB energy efficiency as the main line of development. The evolution process of CPB technology is divided into four stages: volumetric backfill， structural backfill， functional backfill and intelligent backfill， respectively. Correspondingly， the concepts， functions and categories are discussed in detail.It is concluded that the current development stage of CPB is structural backfill. With the continuous development of mine production practice and science and technology， functional backfill and intelligent backfill will become the new development direction of CPB. It will further innovate backfill materials， backfill technologies and backfill equipments， and have an important and far-reaching impact on deep mineral resources exploitation and the transformation and upgrading of mines in the future.

Study on the Corrosion Behavior and Protection of Reinforcing Steel Bar in Cemented Backfill Bottom of Coastal Mine

QI Kuan, WANG Kun, LIN Zhixiang

2021, 50(03): 11-18.

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The exploitation of resources in coastal area is one of the trends of contemporary mining development. Cemented backfill bottom （CBB） stability is the key factor of underground safety mining. However， the CBB can be corroded and lose strength easily under the brine environment in coastal mines， posing huge threatens to the coastal resource exploitation. Based on the engineering background of a large-scale coastal gold mine in China， this study collects samples on site， simulates the internal corrosion environment of the filling false bottom by using self-made laboratory equipment， and uses electrochemical analysis and other interdisciplinary methods are used to study the corrosion behavior of HPB235 steel in the CBB. The strength test and XRD analysis of cement paste test block show that salt halide ion is conducive to the formation of hydration reaction products， and is beneficial to the early strength of cemented test block. The main reason for the instability of CBB is the corrosion of HPB235 reinforcement structure.And the steel electrochemical corrosion behaviors under different protective measures are studied by open circuit current measurement， potentiodynamic polarization test， electrochemical impedance spectroscopy （EIS） and weight-loss method respectively. The result shows that significant corrosions have been found in the unprotected steel bars. The corrosion rate is up to 4.828 g/m2/d. And the epoxy resin coating is proven to be an effective measure which can reduce the current density by 95.8% and the corrosion rate by 93.8%. However， the corrosion inhibitor can only be an auxiliary measure based on its limited effect.

Analysis of the Influence Factors of Paste Stirring Based on Discrete Element Method

LI Xue, LI Cuiping, YAN Bingheng, HOU Hezi

2021, 50(03): 19-27.

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Before the paste is pumped or self-flowed to the well， it must be fully stirred to keep it homogeneous， enhance pumpability and ensure filling strength. In order to study the effect of mixing process parameters on paste homogeneity， the rheological characteristics of the paste were explored firstly， and the slump experiments were carried out to measure the rheological parameters of the paste. Based on the rheological properties of the paste， the full tailing paste was regard as a wet particle group with strong viscosity， a paste discrete element model was established by using Hertz-Mindlin with JKR contact method to simulate the slump experiment. The experiment and simulation results were compared to check the model parameters. Based on the paste discrete element model， a two-axis screw conveyor numerical model was constructed to investigate the effect of different process parameters on the degree of paste mixing. The research shows that the filling rate affects the stirring effect， and the mixing effect is better when the filling rate is 0.6， and the optimal filling rate should be in the range of 0.5~0.7； the stirring speed can promote vigorous movement between particles， but the rotation speed too large will also reduce the mixing degree of the material and affect the homogeneity of the paste. When the mixing speed is 10 rpm and 30 rpm， the mixing degree of the slurry is better. Considering the discharge efficiency， 30 rpm is the optimal stirring speed of the conveyor.

Optimization Test of the Proportion of Phosphogypsum-slag Composite Cementitious Material

LI Hongye, YANG Xiaobing, WEN Zhenjiang, GAO Qian, WANG Yongding

2021, 50(03): 28-33.

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In view of the high cost of using cement as cementitious material for filling in Jinchuan Mine，new cementitious materials for mining are developed by utilizing local solid waste resources.Firstly，the physical and chemical analysis of the test materials is carried out，the orthogonal test of the strength of phosphogypsum-slag composite cementitious materials is done， and on this basis， the optimum proportion of phosphogypsum-slag composite cementitious materials is determined by the optimum test.Then，the factors affecting the strength of phosphogypsum-slag composite cementitious materials are analyzed， the microstructure of hydration products at different ages is observed by scanning electron microscopy，besides that，the cost of phosphogypsum-slag composite cementitious materials is calculated.The study results show that the early strength of phosphogypsum-slag composite cementitious material is lower than that of later strength； the optimum ratio of phosphogypsum-slag composite cementitious material is determined by optimizing the ratio of 7% quicklime， 30% phosphogypsum， 2% mirabilite and 61% slag powder； SEM showed that ettringite and C—S—H gel are the main hydration products， and with the growth of curing age， the structure became close and the strength increased continuously；and the cost calculation of the optimum ratio of phosphogypsum-slag composite cementitious material is carried out. The cost of cementitious material is 180 yuan/t， which is 44% lower than the cost of 38.5 non-standard cement used in Jinchuan Mine.The pipeline transportation characteristics of composite cementitious material filling slurry are measured， and the results can meet the requirements of gravity transportation in Jinchuan Mine.

Experimental Study on the Effect of Tailings Particle Size on Early Strength of Cement Paste Backfill

LI Hongbao, GAN Deqing, E Xinyu, CHEN Chao, LIU Zhiyi, ZHANG Youzhi

2021, 50(03): 34-39.

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In order to improve the utilization efficiency of classified tailings and realized the effective application of cemented paste backfill in mine， the strength test of different cement-tailing ratio （1∶6， 1∶12， 1∶20） and different mass concentration （65%，70%，75%） was designed based on the analysis of physicochemical properties for the unclassified tailings in Jidong area， in combination with X-ray Diffraction （XRD） analysis and scanning electron microscope （SEM） analysis， to study the effect of tailings grain on early strength of cemented paste backfill （CPB）， hydration products and pore structure. The research shows that the tailings particle size has a significant influence on early strength of CPB， that the fit to the cement hydration can be effectively improved when the tailings particles a certain fineness， as the particle size decreases， the early strength of the CPB is greater， and it is more sensitive to changes in the cement-tailing ratio and mass concentration. Based on the characteristic indexes of tailing， an early strength prediction model about tailing particle size， cement-tailing ratio and mass concentration was established， the correlation coefficient R>0.95， the error rate <2%， so the correlation is good， and the prediction result is reliable. It is suggested the cement-tailing ratio of cemented unclassified tailing backfill （CUTB） in Jidong area in the range of 1∶6~1∶8， and the mass concentration is higher according to the working conditions of the filling system. Under the same conditions of the mix proportion scheme， as the particle size of the tailings decreases， the C—S—H gel generated during the early hydration of the CPB， and the pore size and number also decrease， the macro behavior is the increase in strength. Finally，the test was designed in an iron mine in Jidong area，so as to further verify the reliability of the strength prediction model， the average error of the results was 3.49%， indicating that the model can accurately predict the early strength of CPB AND provide a basis for iron mine backfill design.

Study on Synergetic Mechanism of Ore Pillar-Filling Body System

HONG Wei, SUN Guanghua, LIANG Shibo

2021, 50(03): 40-45.

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In order to deeply analyze the co-action mechanism of ore pillar and filling body， aiming at the point-pillar filling mining technology， the system model of ore pillar and filling body was abstracted， and the mechanical model was constructed by using FLAC3D numerical simulation software. The co-action relationship and bearing mechanism of ore pillar and filling body were comprehensively analyzed from the whole and local perspectives.The results show that the filling body has four effects on the ore pillar， that is， increase the peak strength of the ore pillar， limit the radial displacement of the ore pillar， delay the failure of the ore pillar and strengthen the bearing capacity of the broken ore pillar. Under the action of the filling body， the bearing characteristics of the ore pillar were significantly improved， and the peak strength was increased by 34%.From the perspective of the whole， the mechanical behavior of the filling body in the bearing process of the system was shown as overall support-passive bearing-displacement constraint-joint bearing.The essential reason why the ore pillar becomes the main carrier in the early stage of loading was the difference of elastic modulus between them.From a local point of analysis，in the system，the central ore pillar and filling body interaction， mutual assistance，and in the process of bearing，the load-bearing mechanism has obvious synergism，to keep the whole bearing capacity of the plane， in addition， the stress stat of the filling body and ore pillar at the system height h=75 mm position was significantly higher than that of the system height h= 50 mm position. The above analysis can provide reference for the optimizaiton and design of mine stratified filling mining.

Study on the Broken Rock Zone of Roadway in Skarn Copper-iron Mine Based on Geological Radar

YU Qinglei, PU Jiangyong, LE Zhihua, CHU Jixiang, JIANG Zhaoyang, GAO Xiaolong

2021, 50(03): 46-53.

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The determination of broken rock zone of roadway can improve the pertinence and effectiveness of roadway support design. However， for skarn deposit， due to the difference of metamorphism，it results in great spatial variety of skarn physical and mechanical properties. Low strength and swelling in water of skarn rock brings difficulty for the determination of broken rock zone of roadway. Aiming at the problem of underground roadway support in weak skarn deposit， using geological radar to detect the broken rock zone of surrounding rock of roadway was introduced in the skarn copper-iron deposit of Taiping Mine. The distribution characteristics of broken rock zone of surrounding rock mass were analyzed and the influence of rock mass quality on the detected results was discussed.The study results show that the properties of the surrounding rock mass of roadway in Taiping Mine are complicated and the differences of the broken rock zones in the roadway are large. The thickness of broken rock zone of crushed marble roadway is mainly within 1.75 m， while the thickness of broken rock zones of altered diorite roadways and skarn roadways are widely distributed in the range of 1.25~3.25 m and 1.75~3.50 m respectively.The bigger the size of roadway is， the thicker the broken rock zone of roadway. The detecting accuracy of the geological radar for the broken rock zones of surrounding rock mass of roadway depends on the difference in dielectric constant of surrounding rock mass between in the broken rock zone and in the outer plastic zone and the weaker the quality of the rock mass is， the less obvious the border of the broken rock zones of roadway on the radar image is. When detecting the broken rock zone in the roadway supported by bolt-mesh-shotcrete， the metal mesh has a shielding effect on the electromagnetic wave of the radar.When the mesh grid is small enough， it will affect the detection result of the geological radar. This work that using geological radar detects the broken rock zone of surrounding rock mass of roadway provides a reference experience for the mines with similar geological conditions.

Experimental Study on Destruction Effect of Blasting Crater Under Unidirectional Initial Load

YANG Haitao, YI Haibao, WANG Guangcheng, ZHANG Xiliang, ZHOU Jian, LI Erbao

2021, 50(03): 54-60.

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Deep mines are usually faced with high ground stress mining environment， and high ground stress reacts to the process of rock blasting.In order to study the influence of unidirectional initial load on the blasting crater，the influence mechanism of initial load on blasting cracks was analyzed， and then the lateral blasting model tests and numerical simulation analysis were carried out.The results indicated that the degree of influence of the initial loaddepends on the magnitude of the explosion load and rock mechanical parameters. And the rock fissure zone was mainly controlled by the relationship between tensile stress and tensile strength. Within the range of the rock fissure zone， the closer to the center of the blasthole， the smaller the effect of the applied load on the fissure. When within the elastic deformation stage of the stress-strain curve of the concrete model， the initial load showed a certain inhibitory effect on the blasting effect. Compared with the no-load state， the unit consumption of explosives at 5 MPa and 10 MPa increased by 35.80% and 90.12%. And the K50 and K80 at an initial load of 10 MPa could be reduced by 1.65% and 0.44%， respectively， indicating that the initial load could also reduce the blasting block rate to a certain extent， which was beneficial to improve the blasting block distribution.The numerical simulation results were in good agreement with the model tests，the research results have certain theoretical guiding role in optimizing the blasting parameters for deep mining.

Study on the Controlled Splitting Blasting Technology of Large Blocks in Underground Mine

HU Zhihang, NING Yuying, WENG Shengjun, ZHAO Jianyu, XU Zhenyang

2021, 50(03): 61-66.

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The large blocks left in the roadway of Beiminghe underground iron mine are difficult to efficiently handle. The surface symmetrical metal energy-concentrating cover is used to realize the rapid splitting of the large blocks. Six sets of blasting tests are performed on the large blocks in the iron mine roadway. Compare the fragmentation distribution， average fragmentation and blasting morphology when the explosion height is 0， 1 explosion height and 2 explosion height， to study the influence of the explosion height and the unit consumption of the explosive on the crushing effect of large block in the parameters of the shaped charge. The results show that when there is no height， the fragments are mainly distributed in the interval of large size 60~80 cm； with the increase of the height of explosion， the fragments are mainly distributed in the interval of medium size 20~60 cm； the favorable height of the explosion makes the large size The average block size in the interval is reduced by about 10%， and the average block size increase in the medium-sized interval is about 30%~45%； under the same explosive height condition， the slight change of explosive unit consumption has little effect on the average value in the interval； the blasting shape is influenced by metal jet morphology， with the increase of the blast height， the degree of secondary crushing of large pieces increases， and the fragments change from axial symmetry to cross-symmetrical. The application of energy-accumulating blasting can effectively realize the controlled splitting of large pieces.

Optimization of Stope Structure Parameters by Caving Method Based on Response Surface Method

ZHOU Baokun, CHEN Xiaoqing, TIAN Yingchun, MA Dong, GONG Guohui, ZHAI Xiaodong, DENG Haoze

2021, 50(03): 67-73.

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In view of the problem that it is impossible to quantitatively analyze the waste rock mixing at the top， side and front of the ore drawing by sublevel caving without pillar， a similarity physical simulation experiment of in-situ replacement method was adopted to obtain the barren ore mixing amount in each part and find the key points of barren ore mixing in each part. 15 group of experiments were design by using Box-Behnken method in Design-Expert.The influence of the interaction among the sublevel height， the distance between roadways and the distance of ore collapse on the mixing of barren ore were systematically studied.A quadratic response surface model with mixed ore ratio as the response value was constructed.The optimal stope structural parameters were obtained by using the response surface analysis method.The optimization results were verified by in-situ substitution method.The results showed that:① The similarity physical simulation experiment of in-situ replacement method was carried out by using the original structural parameters of segmentation height， road spacing and ore collapse distribution spacing with the values of 12 m， 12 m and 3 m respectively.When the ore recovery rate was 80%， the mixing rates of front， side and top barren ores were 16.7%， 8.3% and 2.5% respectively， and the total mixing rate of ore was 27.5%.② Trough the analysis of response surface model， it was indicated that the segmentation height， route spacing and ore collapse step distance and their interactions all have significant effects on the ore mixing rate， the correlation coefficients fitted by the regression model were all close to 1， the predicted data of the equation were consistent with the actual data， and the optimized segmentation height， route spacing and ore collapse step distance were 16.59 m， 17.42 m and 4.02 m respectively.③ When the ore recovery rate was 80％，compared with the original structural parameters，it showed that the barren ore mixing rate on the front and both sides was reduced by 3.6% and 1.7% respectively， the barren ore mixing rate on the top was increased by 0.7%， and the total mixing rate was reduced by 4.6%，which indicated that the ore drawing effect was good.The above study results further indicated that the study approach that using in-situ replacement method to analyze the rule of waste rock mixing，and adopting response surface method to optimize the structural parameters has certain practicability and operability significance，and has certain reference value for the optimization of mine stope structural parameters.

Coupling Synergy Degree Evaluation of Mining Technology for Trackless and Rail Combined Mining in Underground Mines

LI Jielin, YANG Chengye, ZHOU Keping, LI Zhihong

2021, 50(03): 74-79.

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With the development of mining technology and the application of advanced mining equipment， most underground mines in China have gradually switched to trackless mining systems ， but rail mining systems have not been completely abolished， thus forming a trackless and rail combined mining system in some mining areas. In order to evaluate the synergistic effect of the composite mining process system composed of trackless and rail combined mining， based on the theory of coupling synergy degree evaluation and the coupling synergy degree measurement model， the trackless and rail combined mining area of Yunnan Tin Industry Co.， Ltd. was used as the project cases. Then， a coupling synergy evaluation system of mining technology system was constructed to carry out research on the evaluation of coupling synergy degree.The results showed that the benefit value T of the trackless and rail combined mining technology system of the Yunnan Tin Company was 0.65， the coupling degree C was 0.80， the coupling synergy degree D was 0.72， and the synergistic level of the system was "synergy". According to the evaluation results， the suggestions and measures for the optimization of the trackless and rail combined mining technology of the Yunnan Tin Company were proposed. The evaluation model and method provided a new idea for the evaluation of the synergy degree of other mining technology.

Study on Shale Permeability Based on Pore Structure

TIAN Jun, ZHAO Jinhao, ZHAO Lei, JIN Jiaxu, SHI Gaoke, ZHENG Xu, CHEN Tianyu

2021, 50(03): 80-87.

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Shale permeability is very important for exploration and utilization， and the micro pore structure is the main factor affecting shale permeability.In this paper， the TOC content and mineral composition of the shale of Longmaxi Formation and Niutitang Formation were determined.High-pressure mercury injection experiment and low-temperature nitrogen adsorption experimentwere carried out.The pore distribution and permeability of shale were measured.The effect of geological parameters and pore structure on shale permeability was studied.The study results show that: ① The number of organic pores increases with the increasing of TOC content in the shale sample， thus the porosity increases.The permeability of shale increases with the increase of clay mineral content. The pores in brittle minerals are poorly developed and negatively correlated with permeability and porosity. ② Ink bottle-shaped pore structure are distributed in the shale samples of Longmaxi Formation and Niutitang Formation. The pore throat is narrow and the interpore connectivity is poor. The pore size of the two groups of shales is between 4 nm and 40 nm， and the mesopores is the main channel for fluid occurrence and migration.③ The shale samples of Longmaxi Formation have a single peak distribution at a pore size of about 4 nm， and the shale samples of Niutitang Formation have a bimodal distribution at a pore size of about 4 nm and 7 nm.Relative to pore surface area and pore volume， pore morphology and connectivity have a more important effect on shale permeability.

A Brief Overview on the Mechanism and Kinetic Influencing Factors of the Pyrite Surface Oxidation

JIANG Wenrui, TU Zhihong, ZHOU Shu, WU Qi, DANG Zhi, HE Huijun, LIU Chongmin, LIU Jie

2021, 50(03): 88-102.

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Pyrite， as the most common metal sulfide tailings in the mining environment， is easily oxidized to form acid mine wastewater （AMD） in the supergenetic environment， which leads to a series of environmental pollution problems.Therefore， the study of pyrite surface oxidation mechanism and its kinetic influencing factors have always been a research hotspot in the field of environmental pollution control in mining areas.First of all， this paper summarizes the basic structure and physical and chemical properties of pyrite， points out that the pyrite surface oxidation mechanism and regularity study have important significance for reducing the acid mine drainage production in the first place， perfecting the defect in the application of pyrite photovoltaic material，effectively leaching associated precious metal from pyrite structure and improving the earth sulfur cycle.Then， the surface oxidation mechanism of pyrite was systematically reviewed from four aspects: the mechanism of forming AMD by pyrite oxidation， the biological oxidation mechanism of pyrite mediated by microorganisms， the electrochemical study of the surface oxidation mechanism of pyrite， and the transformation mechanism of sulfur elements in the surface oxidation process of pyrite. And then， the effects of humic acid， inorganic acid ions and common oxidants on pyrite chemistry， biology and surface electrochemical oxidation on pyrite surface oxidation kinetics were summarized respectively.Finally， it is pointed out that some in situ microscopic interface research methods could be used in the future to further strengthen the microscopic mechanism of the interaction between microorganisms and pyrite， explore the oxidation law of pyrite surface under multi-factor coupling action， and establish a model to predict the oxidation rate of pyrite under multi-factor coupling in natural environment.

Experimental Study on Beneficiation of a Low Grade Lead-zinc Sulfide Ore in Southwest China

TANG Youyou, CHEN Xiong

2021, 50(03): 103-109.

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In a low-grade lead-zinc ore in southwest China， the lead grade is 2.99% and the zinc grade is 1.57%. The associated silver grade in the ores is 10.80 g/t. Both lead and zinc mainly exist in the form of sulfide. In order to efficiently develop and utilize the low-grade ores， the heavy liquid floating sinking test and the flotation conditions tests of the raw ore were studied. The results showed that: ① The tests for floating sinking were carried out with heavy liquid aiming at the raw ores below 12 mm. When the density of heavy-medium suspension is 2.7 kg/m3， the lead grade and zinc grade of density greater 2.7 kg/m3 product are 10.48% and 5.37%， respectively， which is nearly three times higher than that of the raw ores. The loss rates of lead and zinc in density less than 2.7 kg/m3 products were 4.48% and 6.62%， respectively. ② The lead concentrate with lead grade of 69.26% and lead recovery rate of 95.21%， and zinc concentrate with zinc grade of 59.83% and zinc recovery of 84.26% were finally obtained from the raw ore in the low alkalinity pulp system by the flowsheet scheme of lead priority floatation， zinc and sulfur mixing flotation and then separation. The research results showed the feasibility of pre-separation and low alkalinity flotation of the ore， which has certain practical significance for the development and utilization of this kond of low grade lead-zinc ore.

Experimental Study on Process Optimization of a High Sulfur Lead-Zinc Mine in the Northeast Yunnan

Lü Chao, XIE Feng, XIE Lizhi, LI Bo, MA Yuanlin

2021, 50(03): 110-115.

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Aiming at the problem of the high zinc contents in the lead concentrate and high lead-zinc contents in the sulfur concentrate of a lead-zinc concentrator in the northeast Yunnan ， the experimental study on process optimization was carried out on the basis of the study on process mineralogy of the ores. The results showed that mineral species of the ores are complex， of which the granularity of galena and sphalerite are unevenly disseminated. The one-stage grinding process of "lead-sulfide mixed flotation， separation of the lead-sulfur mixed concentrate with sulfur inhibition and lead flotation， and zinc selection from the flotation tailings after sulfur-lead selection" was obtained on site. While galena， sphalerite and pyrite with fine-disseminated is not fully monomer dissociated. The study puts forward the process of "stage grinding and stage selection" for process optimization. The bulk lead-sulfur concentrate was regrinded and reselected. In the condition of regrinding fineness of -0.045 mm accounting for 70%， the lead concentrate of lead grade of 61.89% and lead recovery rate of 85.43%， and zinc concentrate of zinc grade of 49.05% and zinc recovery rate of 93.91% were obtained enventually. Compared with the indexes before optimization， the lead grade increased by 1.57% in lead concentrate and zinc contents decreased by 1.35% at the same time. The lead and zinc in the sulphur concentrate were lower， and zinc recovery rate of the zinc concentrate increased by 2.43%. At present， the site has completed the transformation of the dressing plant according to the optimized process. The vertical spiral mixing mill has been used for the two-stage grinding. The production operation is good， and the production indexes have been improved compared with the previous production.

Study on the Beneficiation Processing of A Gallium-Containing Skarn-Type Scheelite in Linzhi， Tibet

LI Daihui

2021, 50(03): 116-123.

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The WO3 grade in a skarn scheelite in Xizang province is 0.52% and the gallium content is 19.08 g/t. The scheelite is of coarse grain size and belongs to medium-coarse grain dissemination. In order to develop a reasonable beneficiation process， representative ore samples were selected for beneficiation process tests， and the recovery process of associated element gallium was explored using leaching process. The test results showed that: ① under the condition of grinding fineness of -0.074 mm accounting for 75.0%， sodium silicate as inhibitor， 733 as collector and sodium carbonate as regulator， tungsten coarse concentrate with WO3 grade of 12.34% and WO3 recovery rate of 64.91% was obtained through the closed-circuit test of one roughing， two cleaning and two scavenging. ② Tungsten concentrate with WO3 grade of 66.20% and WO3 recovery rate of 95.12% was obtained through the closed-circuit test process of tungsten warming cleaning with coarse tungsten coarse concentrate as feeding ore. ③ The optimal leaching conditions of gallium as a associated element are as follows: stirring temperature of 90 ℃， H2SO4 dosage of 350 g/L， leaching time of 6 h， leach aid agent CaF2 dosage of 2.5 g， liquid-solid ratio of 8∶1， stirring speed of 300 r/min. The leaching rate of gallium is 62.55% in the best condition.

Recovery of Lithium from a Granite Type Spodumene by Gravity-color-flotation

LIU Guangxue, PENG Tuaner, LIU Lei, LI Shulei

2021, 50(03): 124-129.

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The consumption of lithium resources in China is increasing by years. The grade of domestic ore-type lithium resources is low， and the development of brine type lithium resources is difficult. The lithium concentrate products can not meet the domestic production needs. A foreign spodumene jigging middling ore was purchased as an additional product of imported lithium concentrate. In order to explore its beneficiation process， the beneficiation test was carried out based on the research results of ore properties using gravity-color- flotation combination process. The results showed that: ① The content of Li2O in the sample is 3.60%. The main valuable minerals are spodumene， and the main gangue minerals are feldspar， quartz and mica. The granularity of spodumene is more than 1 mm， and the granularity of gangue and aggregate is more than 2 mm. ② When the density of heavy liquid is 2.85 g/cm3， spodumene concentrate with Li2O content greater than 5.5% can be obtained with a higher recovery rate. The predicted results of two-stage continuous heavy medium cyclone separation obtained by computer simulation are in good agreement with the experiment results， and the industrial promotion feasibility is high. ③ The coarse raw material beyond 0.5 mm adopts the process of screening classification and heavy suspension separation. Under the condition of medium density of 2.70 g/cm3， the heavy liquid tailings with yield of 21.76% and Li2O grade of 0.18% can be discarded. The metal loss of Li2O in the heavy liquid tailings is only 1.09%. ④ After the separation of heavy liquid concentrate by color separator， the grade of Li2O was increased from 5.73% to 6.18%， the concentrate quality was improved by one grade， and the recovery rate of Li2O was as high as 89.23%. ⑤ Color-separation tailings， heavy liquid middlings and ores below 0.5 mm were regarded as mixed middlings with the Li2O grade up to 2%~3.57%， a flotation concentrate with Li2O grade of 6.53% and Li2O operation recovery of 91.51% was finally obtained through "one roughing， two cleaning and two scavenging" with self-developed EL as spodumene flotation collector. The whole process test separation index is excellent， which effectively reduce the cost of grinding and has a certain value of engineering promotion and application.

Experiment Research on Gold Extraction Process of A Gold Leaching Residue by Oxidizing Roasting and Leaching

XU Hailong, LI Yanjun, WANG Shaoxing, LIU Jie

2021, 50(03): 130-135.

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The grade of Au in the gold leaching residue from a gold smelter in Jiangxi Province is 2.7 g/t， which has a high recovery value. However， the contents of harmful impurities S and As in the leaching residue are high up to 7.54% and 1.98%， respectively， mainly in the form of pyrite and arsenopyrite. The gold particles wrapped in the two minerals are also extremely difficult to be separated under the condition of ultra-fine grinding. In order to effectively recover the gold particles in the tailing residue， a process of oxidation roasting and leaching was adopted to treat the sample based on its properties. The leaching test was carried out under the conditions of pH value of 12， leaching agent JC dosage of 5 kg/t， stirring leaching time of 6 h. The optimal roasting conditions were determined by condition test as follows: roasting temperature of 500 ℃， roasting time of 30 min， air flow of 500 mL/min， and leaching fineness of -0.038 mm accounting for 98.85%. Under the optimal roasting conditions， the grade of Au in the leaching residue is reduced to 1.0 g/t， and the leaching rate of Au reaches 65.52%. The results of chemical analysis and thermogravimetric analysis showed that cracks and pores appeared in the samples. The sulfide ores such as pyrite and arsenopyrite are transformed into oxidized ores during roasting， which reduce FeOOH cover and the consumption of leaching agent， and thus facilitate the leaching reaction. The research results provide reference for the utilization of refractory gold deposits of the same type.

Study on Process Mineralogy of an Iron Ore in Hebei Province

GAO Chunqin, ZHANG Lin, WANG Hailiang

2021, 50(03): 136-141.

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A certain iron ore in Shahe County，Hebei province，is rich in iron and contains valuable elements such as sulfur and cobalt. In order to study the process mineralogical characteristics of the ore and formulate a reasonable beneficiation scheme for achieving the comprehensive utilization， the research about material composition，ore structure，embedding characteristic of the major minerals，degree of dissociation of the value minerals were carried out by chemical analysis， XRD， microscope and MLA. The results showed that the contents of Fe，CO and S are 39.98%，0.017% and 1.89%， respectively. Fe is mainly in the form of magnetite，Co and S are mainly in the form of pyrite. The main gangues minerals are carbonate minerals like calcite and dolomite. The ore is mainly massive structure and granular structure. Magnetite and pyrite are mainly medium and fine particles， which are closely related to each other， so better monomer dissociation degree needs to be obtained by fine grinding.According to the results of process mineralogy，the mineral process of “discarding by dry magnetic separation， grinding，iron selection by low intensity magnetic separation，flotation for cobalt and sulfur” is recommended for the ores.

Study on Process Mineralogy of Bottom Blown Smelting Slag

WANG Jinliang, ZHOU Rui, LIU Yuan, LIU Yanqing, LUO Xianping

2021, 50(03): 142-147.

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In order to recycle the valuable metals in the copper slag， the analysis methods， such as XRF， XRD， SEM， EDS and BPMA， were used to study process mineralogy of the bottom blowing smelting copper slag. The main composition of smelting slag， main minerals components， copper phase occurrence state were found out. The embedded characteristics， disseminated granularity and dissociation degree of the important mineral phases in the slag were studied. The results showed that: ① The main valueable metal in the smelting slag are Cu， Fe， Pb and Zn， and the impurity components is mainly SiO2. ② The main minerals in the smelting slag are matte， iron olivine， ferrite and glass phase. The main copper-bearing minerals are matte， metallic copper， chalcopyrite and copper oxide， and the contents of matte is the highest， with the distribution rate of 92.69%. ③ The distribution of particle size of matte in the smelting slag is not uniform， mainly in the form of granule or round point distribution in the slag， which is closely related to the distribution of lead sulfide， iron olivine， glass phase and ferrite. ④ The metal copper is mainly long granular and round granular， and most of the produced copper was wrapped or connected by ferrite， iron olivine and glass phase. ⑤ Ferrite is lobate matted crystal after amplification. Ferrite is closely related to metal copper and matte and is closely associated with iron olivine and other sulfide ores. ⑥ Iron olivine is closely related to metal copper and matte， wrapping or aggregating the ferrite phase， which formed the base phase of molten slag. ⑦ The glass phase is filled between ferrite， iron olivine， metal copper and matte， take the role of the adhensive. ⑧ The monomer dissociation degrees of metal copper and matte are low， which are 46.13% and 33.81%， respectively， and mainly distributed in the range of 0.020 and 0.038 mm. Therefore， it's important to paid attention to the recovery of fine matte and metal copper when recycle the coarse matte and metal copper.

Study on Process Mineralogy and Floatability of a Cryptocrystalline Graphite in North Korea

FU Kaibin, XU Xin, HOU Puyao, LONG Meiqiao, TIAN Li, ZHA Wei, BAI Guiqi

2021, 50(03): 148-152.

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In order to investigate the process mineralogy of a cryptocrystalline graphite ore in North Korea， analysis methods of chemical analysis， X-ray diffraction （XRD）， and scanning electron microscope （SEM） were used to systematically study the chemical composition， mineral composition， particle size distribution， carbon phase and ore structure of the raw ores， and the preliminary process exploration was carried out. The results showed that: ①the fixed carbon content is 70.29%， which is the main valuable element， indicating the raw ores belonging to low-carbon graphite. Carbon mainly exists in the form of graphite， carbonate and organic carbon， and contents are 70.29%， 4.21% and 2.80%， respectively. The ore is steel-gray， with fine crystalline scaly metamorphic structure， dense block structure， reticulated vein structure， and white reticulated calcite， quartz veinlets and speckled and scattered calcite-quartz aggregate can be seen. The contents of graphite， quartz， calcite， sericite， pyrite are 70%， 15%， 8.0%， 5.0% and 1.0%， respectively. The relationship between graphite and gangue mineral inlay is complex. ②Based on the process mineralogy and the separation and purification process of cryptocrystalline graphite， the stage grinding and stage separation process is preliminarily adopted with emulsion kerosene as collector， MIBC as foaming agent and sodium silicate as inhibitor. The graphite concentrate with fixed carbon content of 87.40% and recovery rate of 93.11% was obtained by "two roughing， seven cleaning and one scavening". In order to obtain high quality graphite concentrate， the combined process of "flotation and chemical purification" was considered to be adopted.

Geological and Geochemical Characteristics and Ore-prospecting Prediction of the B.Houayluang Gold Deposit in Bak-Ou County，Laos

XUE Yunsong, LI Xiangtao, ZHOU Wei

2021, 50(03): 153-163.

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B.Houayluang Gold Deposit in Bak-Ou County， Laos is located in the extension part of the southern Sanjiang metallogenic belt in Yunnan Province， which is an important metallogenic area of hydrothermal type Pb-Zn deposit， volcanic sedimentary type Cu deposit， porphyritic-magmatic hydrothermal type Cu-Au deposit and sedimentary type deposit. In order to find out the potential of copper-gold polymetallic mineral resources in the mining area， based on the working results of geological， remote sensing， geophysical and geochemical exploration， exploration engineering investigation and so on in the area，the geological and metallogenic background， geological and geochemical characteristics， metallogenic model are analyzed，and three prospecting target areas are divided in the study area，i.e. western prospecting target area （Ⅰ），eastern prospecting target area （Ⅱ） and southern prospecting target area （Ⅲ）.The area of western prospecting target area （Ⅰ） is about 13.63 square kilometres， two faulted structures are developed in the area， five geochemical comprehensive anomalies （HT1， HT2， HT4， HT5， HT6） are delineated， one gold mineralization point is discovered in B.Houayle， seven gold mineralized bodies are disclosed through the trench and stripping engineering， mineralization occurs mainly at the contact edge of altered sericite， diorite， limestone and other epimetamorphic rocks， and it is predicted that the target area （Ⅰ）has good prospecting potential for Au deposit.The area of eastern prospecting target area （Ⅱ） is about 5.18 square kilometres， one geochemical comprehensive anomalies （HT3） is delineated， two copper mineralized veins are discovered in the quartz fracture belt， andesite is the surrounding rock， and it is predicted that it has prospecting potential for Au or Cu deposit in target area （Ⅱ）.The area of southern prospecting target area （Ⅲ） is about 1.88 square kilometres， A NE-SE fault passes through the west side of the area， the B.Houaykha gold mine point is discovered， two gold mineralized bodies （belts） are disclosed through the trench and stripping engineering， mineralization occurs mainly in altered andesite， and it is predicted that the target area （Ⅲ） has prospecting potential for Au deposit. It is concluded that the formation of mineralized bodies may be related to the lithology， rock mass or fault structure， this deposit belongs to structural meso-epithermal hydrothermal type gold deposit.Based on the above discussion results，some prospecting indicators from the aspects of geochemistry， structures， alteration of surrounding rock and mineral assemblage are proposed，which have an reference significance for Au-prospecting in Sanjiang metallogenic belt in China.

A Measuring Method in Situ Based on Combined analysis of BIF Iron Ore

LIU Shanjun, YU Moli, WANG Dong

2021, 50(03): 164-168.

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The determination of iron ore composition is very important to measure iron ore quality. The traditional method has the defects of heavy workload， low efficiency and long period. It is difficult to determine the content of all components in iron ore only by using single spectra. In the study， Anshan type iron ore was used as experimental samples. The reflectance spectra and emission spectra of the experimental samples were combined. The composition contents of samples were determined by application of spectral analysis technology. The results showed that the contents of Fe3O4， Fe2O3 and SiO2 in the samples， as well as the grade and magnetic susceptibility can be inversed by combining reflectance spectra and emission spectra. Then the model was applied to the field. The distribution of iron ore was basically consistent with the iron ore enrichment in the mining area. The average predictive residual of the grade in iron ore was 3.5%. The prediction results of the model were ideal. The method has the advantages of low working strength， conveniently， quickly， efficiently and no pollution. It can reduce the test error on the basis of further model optimization in the future. It provides a new technical method for intelligent perception of rock and mineral resources ， unmanned mining， intelligent mining and intelligent ore blending in the future.

Study and Development of a Simulation Teaching Experiment System for Mining Subsidence Based on MATLAB and FLAC3D

WANG Lei, TENG Chaoqun, JIANG Kegui

2021, 50(03): 176-183.

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The mechanism and laws of rock formation movement and surface subsidence in mining operation are the core basic theories of Mining Subsidence Science. The relevant teaching content is complex and abstract， which is the focus and difficulty of course teaching.In view of the poor classroom effect of conventional teaching methods， and many shortcomings of existing computer simulation teaching of mining subsidence，this paper comprehensively integrates the principles and methods of mining subsidence， the current hot issues of mining subsidence studies and the advanced simulation teaching design methods， a simulation teaching experiment system for mining subsidence based on the MATLAB and FLAC3D is construsted.The system mainly includes two modules:① The simulation module of rock formation movement mechanism based on the coupling of MATLAB and FLAC3D. This module aims at the teaching content related to rock formation movement in mining， and realizes the simulation of the rock formation movement mechanism and the law of formation movement through the complementary function coupling of MATLAB numerical calculation and expression and FLAC3D numerical simulation. ② The simulation module of surface subsidence law based on MATLAB GUI. This module is aimed at the related teaching content of surface subsidence in mining， and based on MATLAB GUI，developed three surface subsidence law simulation sub-modules，namely，mining subsidence prediction principle simulation， intelligent parameter inversion principle simulation and mining subsidence law simulation， and realized the temporal and spatial law of surface subsidence simulation. The system developed in this paper has a friendly interface and simple operation， and students can fully understand the mechanism and law of rock movement， the principle of mining subsidence ， and carry out innovative experiments of solving related prediction parameters by using the human-computer interface， so as to effectively improve the quality and effect of teaching. Teaching practice shows that students' comprehension can be greatly improved， and the innovative spirit and learning interest can be cultivated by using the constructed teaching experiment system. The research results of this paper is help for effectively solving the bottleneck problem in the teaching of Mining Subsidence Science.

Risk Assessment of Collapse Disaster in Goaf of Metal Mine Based on Attribute Recognition Theory

JIN Hao, CHEN Yanhao, ZHOU Zongqing, CHENG Shuai, SUN Zizheng, SHANG Chengshun, WANG Chao

2021, 50(03): 184-190.

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The risk assessment of goaf collapse disaster is the key to ensure safe production in mining area. Based on the improved attribute mathematics theory，a risk assessment model of goaf collapse disaster was established，and the risk grade of goaf collapse disaster was evaluated. Firstly，geological factors， mechanical properties，goaf parameters and construction factors are selected as the first-class indicators of attribute evaluation. Secondly，using the principle of importance and the difficulty of obtaining，the four primary indicators were divided into 14 secondary indicators. Thirdly，the analytic hierarchy process method was used to assign weights to the attribute evaluation indicators， and analyze the attribute measure. By constructing the attribute measure function of each evaluation indicator， the single-index attribute measure was calculated and the comprehensive attribute measure was improved. Finally ，the numerical simulation was applied to conduct risk assessment of goaf collapse，and the 3D simulation model of goaf and its surrounding rock was established by FLAC3D software，and the distribution law of plastic zone was analyzed. Based on the established risk assessment system and confidence criterion，the field parameters of Gongchangling mining area were verified，and the risk grade C2 of collapse was evaluated，which indicated that the goaf had medium risk，and the evaluation results were in good agreement with the actual field conditions，which verified the reliability of the evaluation model.

Study on Closed Dust-removing and Purification Technique of Back Dust of High-deep Straight Shaft

ZOU Changfu

2021, 50(03): 191-197.

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The metal mine has high concentration of deep dust， long duration， wide pollution range， and serious damage to the workers. In order to solve the problem of dust return pollution at the unloading port of high-deep straight shaft， aiming at the characteristics and production status of the unloading operation of shaft，the characteristics of the dust returning from the unloading of shaft were analyzed， and the induced air volume generated by the dust return after the unloading of shaft was studied. Based on the study on the characteristics of the returning dust and the induced air volume， control measures for the closed dust extraction and purification were proposed. Combined with numerical simulation of Fluent software，the key technology of closed dust control and dust extraction air volume were studied in depth， the closed dust control method of well pass was improved，and the dust volume was determined.Aming at the continuous operation characteristics of unloading operation surface，a new dust control technology of air curtain on unloading working surface with large cross section and open space was put forward，combined with rigid closed system， the complete airtight dust control of the well pass was realized.According to the current production status of high-deep straight-through shaft in Xiadian Gold Mine，the application on the dust-removing and dust-cleaning technology of shaft was done.The results indicated that after the treatment ，the total dust concentration in the shaft was reduced from 378.3 mg/m3 to 5 mg/m3， and the dust reduction efficiency is 98.7%. The respiratory dust concentration was decreased from 133.3 mg/m3 to 3 mg/m3， and the dust reduction efficiency reached 97.7%，the dust control effect was good. The surrounding environment of the wellhead before and after treatment was obvious.The study results show that the full airtight system combining air curtain dust control and rigid airtight could realize the transparent and airtight dust control on the unloading working surface of large cross section open space，and is equipped with the high-efficiency wet dust collector suitable for treating air volume，which is help for solving the problem of dust pollution in high-deep straight shafts.

Study on the Optimization of Protective Measures in Plain Area Downstream of Dam Break of Overhead Tailings Pond

LI Shujing, LIU Xiaofeng, WU Ligong, XIAO Lixing, YAO Chi, JIANG Qinghui

2021, 50(03): 198-205.

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The safety risk of overhead tailings pond is huge， and it is easy to cause major safety accidents. Therefore， it is of great significance to study the evolution process and downstream protection measures of debris flow in overhead tailings pond. Aiming at the tailing pond with open plain terrain in the downstream， through two methods of model test and numerical simulation， the sediment deposition thickness and inundation range of each position in the downstream of the dam body under different layout forms of the downstream retaining dam are studied. On this basis， the layout forms of the downstream protective retaining dam are optimized. Based on the analysis of the downstream sediment deposition thickness and inundation range after dam break， it can be concluded that:① the retaining dam has the dual function of retaining and diversion， and the diversion is divided into transverse diversion and longitudinal diversion. ② the function of the retaining dam is different with different dam body angles: the larger the angle between the dam body is， the more obvious the retaining function is； the smaller the angle between the dam body is， the more obvious the diversion function is. ③ The retaining dam with an included angle of 128° is the best protective measure ， because the angle of the dam type can slow down the impact force of the discharged sediment on the dam body， and the two-way diversion of the dam type increases the flow range of the discharged sediment， reduces the thickness of the downstream sediment deposition， enables the sediment to be effectively discharged around， and reduces the harm to the downstream residents. The research results can provide decision-making basis for the optimization of downstream protective measures of tailings pond.

Photocatalytic Degradation of Ethyl Xanthate in Wastewater by Co-g-C3N4/La-TiO2 Composite Material

ZHANG Yaxuan, YAO Zhenlong, WANG Zunsheng, WANG Cunhui, OUYANG Erming

2021, 50(03): 206-213.

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In order to degrade the flotation agent ethyl xanthate remaining in the beneficiation wastewater， a composite photocatalytic material Co-g-C3N4/La-TiO2 was prepared by the sol-gel method. The morphology， crystal structure， photochemical properties and surface chemical properties of the samples were characterized by SEM， XRD， UV-Vis， PL and XPS spectrum.The effects of catalyst dosage， simulated wastewater pH， initial concentration of ethyl xanthate and time on the photocatalytic effect were studied. Free radical capture experiments have also been carried out to determine the active groups that play a role in the photocatalysis process. The results showed that La and Co in Co-g-C3N4/La-TiO2 exist in the form of La3+ and Co2+. The band gap decreases and the absorption band edge was red-shifted， thus the photocatalytic efficiency is high. Under the conditions of catalyst dosage of 1 g/L， ethyl xanthate concentration of 60 mg/L， and pH of 10， the degradation rate of ethyl xanthate reached 99.1% after 60 minutes of photocatalysis reaction. Holes （h+）， hydroxyl radicals （·OH） and superoxide radicals （·O2-） all have a great contribution to the degradation of ethyl xanthate during the process of photocatalytic oxidative， and the degree of contribution is ranked as ·OH＞h+>·O2-.

Study on the Adsorption of Cd（Ⅱ） in Simulated Wastewater by Tailing Algae-Montmorillonite System

XIA Ling, TAN Jiaqi, WU Li, SONG Shaoxian

2021, 50(03): 214-220.

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Mine wastewater contains cadmium and other heavy metal ions， which are highly toxic， and its direct discharge will cause serious pollution to the surrounding water and soil and harm human health. Tailings algae（Didymogenes palatina XR）， which is of heavy metal ion tolerance， isolated from lead-zinc mine tailings mixed with montmorillonite and then the mixture were regarded as research object to explores the adsorption effect for Cd（Ⅱ） removal in simulated mine wastewater. The surface characteristic of algae-montmorillonite system was observed by scanning electron microscope， and the function types of the samples were determined by the FTIR and XPS and adsorption mechanism was analyzed. The results showed that the saturated adsorption capacity of single tailing algae and montmorillonite is 97.21 mg/g and 40.57 mg/g when the solution pH is 5.5. Under the same experimental conditions， the saturated adsorption capacity of tailings alga-montmorillonite system with a mass ratio of 1∶5 is 60.07 mg/g， which is 20.12% higher than the theoretical adsorption capacity of 50.01 mg/g. The characteristic groups on the surface of tailings algae cells played a crucial role in the process of fixing cadmium in the system， and the phosphorus-related groups not only participated in the fixing of cadmium in the system， but also participated in the formation of tailings alga-montmorillonite system. Mixing the tailings algal with montmorillonite and using the samples for the removal of Cd （II） in the simulated wastewater， not only improved the maximum adsorption capacity of the sample for Cd （II） removal， but also enhances the repairation stability in the process of mine wastewater. The results is of great significance in the repairation of wastewater containing cadmium.

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