Thickness Of Ore Body Research Articles

Microseismic Monitoring and Disaster Warning via Mining and Filling Processes of Residual Hazardous Ore Bodies

The thick ore bodies in the Xianglushan tungsten mine have been irregularly mined, forming a super large, connected irregular goaf group and tall, isolated irregular pillars inside. At the same time, there is a production capacity task of recovering residual and dangerous ore bodies. This poses the potential for serious ground-pressure disasters, such as roof caving, pillar collapse, and large-scale goaf collapse during mining. Based on the actual needs of the site, we established a microseismic monitoring system. After analyzing the mining and filling processes and their relationships, and, combined with the distribution characteristics of microseismic multiple parameters, we constructed a ground-pressure disaster warning mode and mechanism. We analyzed the stability of the goaf, further formed a warning system, and achieved disaster warning. In response to the current situation of the difficulty of early warning of ground pressure in the Xianglushan tungsten mine, continuous on-site monitoring of existing goaves, point pillars, and strip pillars, as well as analysis of stress changes during dynamic mining and filling processes, we explored scientific and reasonable early warning mechanisms and models, understanding the relationship between the changes in microseismic parameters during dynamic mining and filling processes and ground pressure, studying and improving the reliability of underground microseismic monitoring and early warning, and achieved the internal connection between building early warning systems and the prevention of ground-pressure disasters. The results indicate that the mining and filling process of the ore body is the main factor in maintaining a stable and balanced distribution of underground ground pressure in mining engineering. Microseismic monitoring can invert the evolution of ground pressure and form a feedback system with ground-pressure warning, achieving mine safety management.

Chemical Characteristics of Industrial Geological Parameters and Their Implications in Uranian Overview of Pa Lua - Pa Rong Area

This study investigated the geological properties of the uranium ore found in Pa Lua - Pa Rong area for potential industrial exploitation. A combination of field measurements, modeling and several mathematical approaches were employed to characterize the geological properties of the uranium ore. We found: i) The thickness of the ore bodies ranges from thin to medium, exhibiting varying degrees of instability (Vm = 83.8÷102.8%). The average U3O8 content indicates that the ore bodies belong to the poor ore type, with an unevenly distribution (Vc = 57.9÷100.9%); ii) The morphology and structure of the ore bodies are highly complex, exhibiting irregular variations. The thickness of the ore bodies shows a positive correlation with the uranium content in each body (R = 0.6-0.7); iii) The variograms of the U3O8 concentration and the thickness in various directions exhibit a spherical pattern, indicating an autogenous effect. The most significant variation in uranium content aligns with the dip direction (50°±12.5°), while the least variation aligns with the strike of the ore body (140°±12.5°). The variations in ore body thickness are more straightforward and consistent with those of the uranium content. In summary, these findings provide valuable insights into the characteristics of uranium ore in Pa Lua – Pa Rong area. The results contribute to a better understanding of the geological processes and can inform some effective exploration strategies for uranium resources in this region.

Stability Analysis of Gentle Dip Thick Ore Body Mining Based on the Integration of SURPAC-FLAC3D

Issues of large exposed roof area, poor stability, and significant roof support workload are prevalent in the mining of metal ores with gently inclined thick bodies. In response to these challenges, a downward cemented fill mining method has been proposed to enhance the stability of the surrounding rock and filling body. By integrating SURPAC and FLAC3D software, a three-dimensional numerical model that conforms to the actual geological morphology of the mining area was established. Numerical calculation results indicate that after the first stage of ore body excavation, the surrounding rock settlement mainly occurs in the roof and the hanging wall of the -65m level, with the hanging wall settlement primarily concentrated between the 3rd and 4th vertical exploration lines. The filling body demonstrates a weak compressive stress capacity, leading to a gradual transition of compressive stress to the surrounding rock of the mine stope. As the excavation level increases, the compressive stress on the pillars also increases, forming a compressive stress concentration area at the -65m level. A mixed plastic zone of shear and tension is generated in the roof and hanging wall, while a shear plastic zone is present in the inter-pillar area. The findings of this study offer valuable insights to ensure the safety of mining in gently inclined thick ore bodies.

Геохимическая зональность рудной залежи Ново-Учалинского колчеданного месторождения (Южный Урал, Россия)

Novo-Uchaly essentially zinc (CZn>>CCu) VMS deposit is one of the largest in the Urals. Currently, it is under additional exploration by fans of underground drilling wells and mine workings. The paper describes a novel geochemical zonation of the sulphide deposit (the example of Cu, Zn, Au and In), discusses conditions of formation and factors that caused its complication. We carried geostatistical calculations in addition to the analysis of the zonation of the deposit. The ore deposit is represented by a large subvertical ribbon of a whimsical structure, inclined southward, which is confined to the wing of an inverted large anticlinal fold, cut by mafic dikes and characterized by a complex, combined geochemical zonality. The distribution of Cu and Zn is generally asymmetric. Copper-rich ores tend to the northern wedge of the deposit, and to the south, along its declination, the concentration of Zn increases, while Cu decreases, and the middle part of the deposit is represented by zinc-rich ores. In the section, copper maxima are more often noted in the footwall side of the deposit, and zinc — in the hanging side. The intrusion of a thick gabbro-diorite dyke and subsequent dynamometamorphism, including hydrothermal solutions, caused the redeposition of more mobile Cu in the near-contact zones of the dyke and areas of swell of the ore body thickness. Within the swell of the thickness of the deposit, in the hinge of the fold of the 2nd order, rich copper-zinc ores occur, which are enriched by Zn, Pb, Au, Ag, In, Ba and some other rare elements. The similarity of their behavior in ores is confirmed by their high positive pair correlation. In the ore body, the distribution patterns of gold and indium are rather symmetrical. High concentrations of gold and indium are confined to a sharp bend in the ore body, and small indium maxima occur in the footwall of the ore lode. As a result of dynamometamorphism, the deposit acquired a whimsical structure with the formation of thick swells; ores were significantly recrystallized, and locally enriched by non-ferrous and precious metals.

Change in seismic activity and rockburst hazard in stoping at SUBR’s Kalia deposit

Seismic activity at the rockburst-hazardous deposits of SUBR causes sudden failures in underground excavations in the course of room-and-pillar mining. The regional forecast used seismological observations with determination of coordinates and energy of seismic events. This made it possible to find out that the most of seismic events was connected with natural concentrators: abrupt changes in the thickness of ore bodies down to sterile ground and faulting. Using the kriging method, the contour map was constructed for the sheetlike bauxite deposit thickness in Kalia Mine, in block 5u, Level -1220 m, being mined using the room-and-pillar system. The thickness map of the ore deposit is superimposed on the mining plan. For locating source sites of seismic events relative to the deposit, the vertical sections of the latter were constructed in different directions. The results obtained indicate the susceptibility of the ore body thickness to the effects of seismic events. Using the spatial model section, the seismic circumstances of a rock burst were determined. The numerous studies prove the dependence of energy of a seismic event on the distance between its source and a failure point. The rock mass envelope around an extraction panel where rock falls and failures take place in underground excavations after a seismic event is determined. It is revealed that the total released energy of rocks directly depends on the volume and span of the mined-out stope. With decreasing size of the test block along the strike, the specific energy density increases. The forecast calculation of the total energy of seismic events for the next excavation panel is performed. The procedure to detect the increased energy activity areas is developed. It makes it possible to locate high energy sources in advance.

Justification of underfill in mined-out voids in cut-and-fill stoping

The paper considers the issue of assessing the proportion of unfilled voids in ore mining by the cut-and-fill method with cemented paste backfill. The efficiency of such mining systems is directly related to the proportion of backfill in the mined-out voids. The underfill of such voids may lead to negative processes in undermining, such as rock movements, dynamic events induced by rock pressure and growth of water-conducting fractures. The mined-out void fill factor is the coefficient A which is the ratio of the backfill volume to the void volume. According to standards, it should not be less than 0.98. Such value of the coefficient governs an unacceptable underfill sometimes. The paper substantiates the maximum underfill with regard to the recently predominant transition to the cut-and-fill mining method, as well as the causes of the increasing underfill, such as the uncontrolled roof failures. Based on the statistical processing of in-situ data, it is shown that the proportion of the neglected underfill can reach 0.13% under the most  unfavorable conditions, which is lower than the rated value of the allowable underfill and isincapable to lead to a significant change in the nature of rock movements. The calculated values of the mined-out void fill factor are 0.995–0.998 at the mineable ore body thickness of 20–50 m. Thus, in the modern conditions of copper–nickel ore mining, particularly at Talnakh, the fill factors in the cut-and-fill stoping practice need to be adjusted. The fill factors obtained in this study can be used for the more reasonable calculations when solving issues related to rock mass movements, which, among other things, can have a positive influence on the cost of protection of undermined objects.The authors appreciate participation of members of Norilsk Nickel’s Polar Division Yu. N. Nagovitsin, M. P. Sergunin, A. A. Kisel, A. A. Bazin and A. K. Ustinov in this study.

Substantiation of mining systems for steeply dipping low-thickness ore bodies with controlled continuous stope extraction

Purpose. The solution to one of the important problems of the underground mining method is to substantiate cost-effective, technologically feasible and safe variants for mining steeply dipping low-thickness ore bodies. Methods. Mining systems are substantiated on the basis of a detailed analysis of the developed and existing experiential variants for mining steeply dipping ore bodies, identifying production and economic disadvantages, as well as their causes. Findings.As a result of the research, the pillar raise performance in the mining system with ore shrinkage has been substantiated. The main parameters of the proposed variants for mining systems with ore shrinkage, intended for expansion-type supports and borehole breaking, have been substantiated. A design has been developed of fastening the material-running raises (MRR) and ventilating raises (VR) on the working and ventilation horizons to ensure their performance in the mining system with ore shrinkage. Originality. For the first time, dependences of dilution and labour productivity on the ore body thickness and the type of ore breaking for blast-hole stoping and borehole breaking for a single and “twinned block” have been obtained. In addition, a certain dependence of the loading and delivery performance on the average fractional composition, as well as on the delivery distance, has been obtained. Practical implications. The research is characterized by scientific innovations created for the first time, which are able to ensure the efficiency and safety of mining operations, while creating the ability to manage the loss of minerals and dilution in the block, as well as reaching their calculated optimal ratio in order to achieve the most cost-effective production rate.

Numerical Investigation on Stratum and Surface Deformation in Underground Phosphorite Mining Under Different Mining Methods

With the ending of deep-concave open-pit phosphorite extractions and gradual exhausting of shallow mineral resources, stoping of phosphorite seams has entered or will enter into underground mining. Particularly for excavating slightly inclined thin and medium-thick phosphorite orebodies, roof and surface control under different mining methods is crucial for safe and efficient exploitations. In this study, the study area is located in Kunyang Phosphorite Mine characterized by slightly inclined thin and medium-thick deposits. Based on the occurrence conditions, orebody thickness, dip angle, and more factors, the mining methods of underground phosphorite are selected, including room and pillar mining, cement backfill mining, and caving mining. Numerical analysis on roof deformation and surface subsidence under the three methods is performed. The results show that the amount of roof and surface subsidence decreases successively by the caving method, room and pillar method, and cement backfill method. The maximum roof and surface subsidence by the caving method is 45.7 and 13.3 cm, respectively. Regarding shallow orebodies, the open-pit slope is obviously disturbed by the caving method and room and pillar mining method. Hence, slope displacement monitoring should be emphasized. Compared with the other two methods, the backfill mining method can use mined wastes as backfill materials and has less influence on the roof and surface during stoping and is better at controlling slope stability.

Applicability of manmade bottoms in extraction panels toward sustainable stoping with caving at deep levels in mines

The authors discuss applicability of manmade bottoms (MB) in extraction panels, with fast reinforced-concrete support platform at the ore drawing and haulage level in stoping with caving. The structural components of the proposed-design MB capable to stand high overburden pressure in mining of thick ore bodies using the systems of stoping with caving in the conditions of unstable ore and enclosing rocks, including deep-level mining.

Numerical simulation of the effect of priming methods on result of ore fragmentation in fan-patterned long hole blasting and its application

Fan-pattern long hole blasting is a common method which is widely applied in the sublevel or level mining methods in deposits in which the thickness of ore body is thick and the dip of ore body is steep and the country rocks are comparatively hard. The effect of priming methods on result of ore fragmentation is very important and numerically analyzing its mechanism has a theoretical and practical significance. In this paper, we investigated the damage and fragmentation grain size of ore body in according to the priming methods such as collar, middle and bottom priming by using Ansys Autodyn in detail. The simulation result showed that the producing rate of fine ore and boulder were 9.4% and 36.7% in the collar priming and 5.6%, 26.3% in the middle priming and 5.5% and 23.0 % in bottom priming respectively. This shows that the bottom priming method is more advantageous than the others. The practical design for field application of the fan-pattern long hole blasting was carried out by JKSimblast and the expected result has achieved.

Frame mine structure for underground mining of thick ore bodies

The article describes the research results on the convergent technology for underground mining of thick ore bodies using a frame mine structure. The brand-new concept of the stability evaluation in anthropogenically altered rock mass uses the inter-disciplinary design solutions developed within the scope of nature-like convergent technologies. The nature-like convergent framing technology based on the modern deformation concepts ensures the highest stability of the load-bearing structures in mines. For the quantitative evaluation of the in-situ stress field variation in the course of mining, a new index is proposed – the influence factor. This index-based estimate shows that the strongest effect on the size of induced tensile strain zones in thick ore body mining is exerted by the mining systems with caving. The authors present the stress–strain analysis of the frame mine structure, the mechanism of tensile strain zones, and the level of deformation in enclosing rocks, ore and various-purpose pillars. The design and construction sequence of the new mine structure, as well as the related safety, eco-friendliness and efficiency of mining are demonstrated. A casestudy of stage-wise preparation and extraction of an ore site is presented, including the first stage of formation of artificial separation and protection pillars and the second stage of open stoping with borehole blasting by sections and using VRC.The study was supported by the Russian Science Foundation, Project No. 19-17-00034.The authors highly appreciate participation of N. G. Vysotin, A. M. Yanbekov, S. S. Shermatova, M. A. Kosyreva, Ch. V. Khazhyylai, V. I. Leizer and E. D. Yakusheva from the Research Center for Applied Geomechanics and Convergent Technologies in Mining at the NUST MISIS College of Mining in this study.

Study on monitoring and variation law of strata movement induced by caving mining of slowly inclined large and thick orebody

Study on monitoring and variation law of strata movement induced by caving mining of slowly inclined large and thick orebody

Evolution of secondary stress field during underground mining of thick ore bodies

Rapidly evolving economic crisis generated by the unbalanced confrontation between the technosphere and biosphere dictates finding and implementation of a drastically new technology paradigm of development in the mineral mining sector based on the novel models and ideas about transition to nature-like geotechnologies. Regarding anthropogenic change in subsoil in the course of mineral mining, it is necessary to study the evolution of the secondary stress field in space and time as the structure of this field exerts a dominant influence on parameters of promising mining technologies. The study was supported by the Russian Science Foundation, Project No. 19-17-00034.

Substantiation of the parameters of open stoping mining method with abandonment of unrecoverable pillars

Relevance. Developing inclined ore bodies of low and uneven thickness using mining systems with caving results in great losses and dilution, deteriorating the conditions for ore gravitation. As a consequence, it becomes necessary to slice the barren rock in the lying side to form slopes with the desired angle. There are also characteristic ore losses at the dead end of the drawing drift independent of the ore body thickness, therefore acquiring a significant role under a lesser thickness. The height of the sublevels, limited by the ore body’s inclination, leads to a considerable amount of preparatory and development operations. The absence of actual in-process monitoring of useful component content in the ore drawing doses often leads to increased dilution rates due to the drawing of barren caved rocks of the previously worked overlying sublevel. Thus, the technological solutions search and their design parameters substantiation for the conditions of inclined ore bodies of low thickness is an urgent scientific and technical problem. Research aim is to substantiate the parameters of the open stoping mining which provides for leaving unrecoverable pillars which ensure the drawing of the maximum volume of pure ore under the cantilever of the hanging side rocks. Research methods. The work used a comprehensive research method based on search and design of technically rational options for geotechnology, their technical and economic assessment and mathematical modeling, and determination of stable parameters of mining system structural elements – the chamber span and the pillar width. Results analysis. The optimal variant of the open stoping mining system has been determined. In comparison with the basic technology of sublevel caving, the specific consumption of preparatory and development operations per 1000 tons of mined ore has been reduced by 34%, the cost of mined ore – by 12%, and ore losses and dilution – by 2 and 2.9 times, respectively. The stable parameters of the chamber span and pillar width have been established. Conclusions. The developed technology of sublevel open stoping with double chambers with frontal ore drawing using remote-controlled loading and hauling machines and subsequent caving of unrecoverable pillars of minimum width allows to significantly increase the efficiency of mining.

Study on the Safety Technology in the Process of Mining the Inclined Thick Orebody in a Mine

Study on the Safety Technology in the Process of Mining the Inclined Thick Orebody in a Mine

Rationale for the parameters of steeply inclined ramps of kimberlite pits deep horizons exposing

Research aim is to substantiate optimal road grade when operating 4WD dump trucks and to develop analytical method of calculating the volume of additional spacing of non-mining slopes of an opencast from motor transport lanes placement when exposing deep kimberlite pits with spiral routes. Research relevance. Transition to steeply inclined ramps and 4WD dump trucks is a basic trend in improving the efficiency of deep kimberlite pits mining. In this regard, the issues of substantiating road grades and developing the method of calculating the volume of additional spacing of non-mining slopes of an opencast from motor transport lanes placement are becoming increasingly relevant. Research methodology. When substantiating road grade for 4WD dump trucks the physical principle of minimal action was used as well as dump trucks tractive and dynamic, braking and fuel conditions together with some experimental data. A new notion of “specific action” has been introduced. Optimal grade by the criterion of specific action complies with minimum energy for mined rock lifting under maximum hauling capacity. The elaborated analytical method of calculating the volume of additional spacing of non-mining slopes of an opencast is characterized by the integrated record of basic process parameters of uncovering. Graphical method of finding the angle of the non-mining slope has been proposed being a controlled parameter at uncovering with steeply pitching ramps. Results. It has been determined that optimal grade value by physical criterion of specific action are determined by the dependences between transmission efficiency, road speed and specific fuel consumption by 4WD dump trucks and the total traction resistance in slopes. For CAT-745С dump trucks optimal values slopes for macadamized roads within the range of 0.18–0.24. The patterns of basic mine engineering factors influence on the volume of additional spacing of slopes from motor transport lanes placement. Major effect on the volume of flattening is brought about by the depth of the pit, spiral ramps grade and ore body thickness. So, the introduction of steeply inclined uncovering is primarily recommended in kimberlite open pits when mining thin ore bodies. Scope of results. The obtained results may be applied in deep kimberlite open pits design and operation when introducing 4WD dump trucks. The results may also be applied in ore open pits when uncovering deep horizons by spiral ramps.

Overall Design and Optimization of Mining Sequence in High-Stress Environment of Thick Orebody

After entering deep mining, the stress concentration level because of engineering excavation is considerably greater than the strength of the engineering rock mass. Here, we consider the engineering impact of a high stress environment in the deep mine plan, integrate the high-stress environment and its evolution with the mining process into the mining plan, and realize the balance of improving the stress state and getting the maximum net present value. Using Map3d boundary element simulation software, we planned two vertical and four horizontal mining sequences for deep and thick orebody backfill mining, respectively, and then analyzed the changes in stress and rock mass energy because of mining disturbance. The results show that the surrounding mining sequence can effectively improve the mining stress environment and increase production capacity. Using large-spaced dispersion and mining sequence from the middle to both ends can gradually redistribute the stress to adjacent areas, thus reducing the degree of stress concentration.

МОДЕРНИЗАЦИЯ СИСТЕМЫ РАЗРАБОТКИ МАЛОМОЩНОГО МЕСТОРОЖДЕНИЯ БОГАТЫХ МЕДНОКОЛЧЕДАННЫХ РУД

The purpose work. Substantiation and selection of a safe and effective option of mining technology of the experimental block in the pilot industrial mining of the Skalistoe deposit. Method of research. Analysis and synthesis of project solutions, experience in mining inclined low-thickness ore bodies, economic and mathematical modeling and optimization of the parameters of options mining systems in the conditions of the experimental block. Results of research. As a result of research it was established: - the sublevel caving mining system with the parameters adopted in the project does not guarantee the completeness of the extraction of reserves and the effectiveness of mining operations. Project indicators of extraction by sublevel caving technology with frontal ore drawing are overestimated and difficult to achieve in these geological and technical conditions (combination of low thickness and angle of ore body); project scheme for the delivery and transportation of rock mass seems impractical due to the significant volume of heading workings and increased transportation costs; - eight technically rational options of various mining systems were constructed, most relevant to the geological and technical conditions of the deposit. Five variants of the sublevel chamber system and pillar caving, a project variant of sublevel caving technology with frontal ore drawing and two options flat-back cut-and-fill system were considered; - for mining the Skalistoe deposit, according to the results of economic and mathematical modeling, optimal by the criterion of profit per 1 ton of balance reserves of ore is a option of the technology of chamber extraction with dual chambers, frontal drawing of ore by remote-controlled load-haul-dump machine and subsequent pillars caving, as having the greatest profit; - the calculations justified stable spans of dual chambers (25.3 m) and the width of panel pillars (3 m). With an allowable span of 25.3 m, the roof of the dual chambers will be stable with a safety factor of 1.41, and a panel pillar with a width of 3 m has a sufficient margin of safety (more than 1.6) in the whole range of ore body thickness variation; - the proposed scheme of delivery and transportation of rock mass, which allows to reduce the volume of tunnel works by 26% and the average length of transportation by 10-15% compared with the project. Findings. Developed in the process of modernization the technology sublevel chamber system with double-chamber, compared with the project technology, it is possible to significantly increase the efficiency of mining of the low thickness deposit of rich ores Skalistoe by reducing the specific volume of preparatory-rifled work by 34%, the cost of mined ore by 12%, losses and ore dilution – by 2 and 2.9 times, respectively.

The genesis of regolith-hosted rare earth element and scandium deposits: Current understanding and outlook to future prospecting

Rare earth elements (REE) and scandium (Sc) have become strategical and critical resources to nations worldwide. Currently, regolith-hosted REE deposits in South China and the neighbouring regions provide more than 90% of the global heavy REE (HREE) production. Recent discoveries highlight the potential of exploitable Sc resources from regolith-hosted deposits. Hence, knowledge about the nature and ore-forming processes of these REE and Sc deposits is important to facilitate identification of favourable geological and geomorphological environments and thus to guide exploration of these deposits. Previous studies have confirmed that felsic and mafic-ultramafic rocks are favourable parent rocks for the formation of REE and Sc deposits, respectively. Apparently, these parent rocks are already enriched in REE and Sc, both geochemically and mineralogically, during their petrogenesis. Favorable protolith for the formation of regolith-hosted REE deposits includes granites, syenites, and volcanic rocks with most of the REE hosted in weathering susceptible minerals, for example, synchysite, gadolinite, and hingganite for the HREEs, and allanite, titanite, apatite for the LREEs. Clinopyroxene-rich mafic-ultramafic rocks are ideal protolith for the formation of regolith-hosted Sc deposits. During weathering, REE are liberated during decomposition of the parental minerals and mainly sorbed on clay minerals, notably kaolinite and halloysite. A critical transformation from poorly crystallized, nano-sized halloysite and kaolinite to much more crystalline and larger vermicular kaolinite is observed with progressive weathering. Adsorption capacity of the clay minerals significantly decreases in this transformation, thereby, REE adsorption becomes unfavorable and desorption dominates in the shallow soils, whereas efficient adsorption on the clay minerals could take place in deep regolith. Weathering behavior of Sc is different from the REE. A case study from Australia reveals that Sc is initially sorbed on smectite after decomposition of parental Sc-rich clinopyroxene. Subsequently, Sc is sorbed on neoformed Fe oxyhydroxides, thereby efficiently retain in the shallow Fe-rich duricrust, when smectite is dissolved in more advanced weathering. Mobilization, re-distribution, and accumulation of REE and Sc to form deposits are closely related to the groundwater flow and adsorption-desorption processes of these elements on the supergene minerals. Transport of REE would be dominated as free cations in shallow, acidic soils but the importance of REE-carbonate complexes dramatically increase with depth, facilitating the mobilization of HREE. Moreover, external elemental input from local groundwater would result in precipitation of supergene REE minerals, for example chernovite-(Y) at the Zudong deposit in South China. Supergene processes are key in controlling the formation and preservation of ore bodies. Alternating episodes of intense and weak erosion are favourable to form giant regolith-hosted deposits, whereas an equilibrium state between weathering and erosion also plays a role in the ore formation. Intense erosion would accelerate chemical weathering and liberation of REE and Sc from the protolith for ore formation, whereas intervals of minimal erosion are also required for preservation of thick ore bodies. Pre-concentration of REE and Sc in parent rocks, and favourable supergene environments for the ore formation and preservation remain for further studies. Key scientific questions awaited to be solved include the petrogenesis of geochemically and mineralogically favorable protolith as ground preparation for the supergene ore formation and the concentration mechanism of REE and Sc in this process. Moreover, it is crucial to decipher the occurrence of REE and Sc in different clay minerals and Fe oxyhydroxides in these deposits, and the associated sorption-desorption mechanism. Application of visible light-infrared spectroscopy to the exploration of regolith-hosted REE and Sc deposits deserves particular attention in the future endeavour.

Research on sublevel open stoping recovery processes of inclined medium-thick orebody on the basis of physical simulation experiments.

The gently inclined medium-thick orebody is generally viewed as difficult to extract. This paper presents a sublevel open stoping using long-hole with back filling method, particularly for inclined medium-thick orebodies. This method not only changes the temporal sequence of ore stoping and realizes transportation using gravity and trackless devices, but also improves production capacity and efficiency. Nonetheless, this method also has some disadvantages; for example, the orebody has more contact with country rock, and the method has a more complex loss and dilution process. This paper starts with the analysis of the results of physical simulation experiments that examine the interactive relationship among the lower stope footwall dip angle, the footwall surface roughness, draw point interval and production blast ring and concludes their influence on the ore-recovery ratio in each production cycle. Secondly, based on physical simulation results, the multivariate linear fit was carried out on the SPSS using the dimensional analysis method. Thus a statistical model was developed for investigating the influence of gently inclined medium thick orebody, the footwall dip angle, the footwall roughness and interval of draw points on the recovery ratio, which can accurately forecast the ore-recovery ratio under different parameters in the physical simulation process. The optimal structural parameters obtained from physical simulation and statistical analysis was then applied to industrial experiments. Based on the 3D laser scanning during in-suit experiments, it was found that the lower stope had an 82% recovery ratio and an 18% dilution ratio, while the upper stope had a recovery ratio of 85% and a dilution ratio of 12%. Moreover, the production capacity could be up to 600t/d. The physical simulation and industrial experiments both demonstrate that the new mining method can be adopted for the safe and efficient mining of gently inclined medium-thick orebodies.