Cut-off Grade Research Articles

Determination and choice of optimal cut-off grade value using 3d modeling on the example of domestic bif deposits

Ukraine is in 10 countries with the largest reserves of iron ores, and the iron ore industry and metallurgical complex are budgetary sectors economically important for the country. For now the mining and metallurgical complex is experiencing not the best of times, and experts say that Ukraine is not using its potential, as it should. One of the main steps in inventory calculation is the determination of boundary value. Boundary value is calculated on the basis of geological, economic, technological and social aspects. Using only geological information, you can calculate the most favorable boundary value using geostatistics.
 The main cut-off parameter that determines reserves quality of ferruginous quartzites, which require enrichment by magnetic separation, is iron associated with magnetite Femagn. The paper proposes a tool for choosing the optimal cut-off grade values for evaluating BIF deposits using the example one of the West Azov group deposit. Comparison of cut-off parameters for reserves calculation of iron ores within the Azov Group deposits is carried out.
 To find the optimal cut-off grade Femagn using geostatistics and spatial modeling, we analyzed the dynamics of changes in the amount of reserves from changes of cut-off grade Fe. Fluctuations in average Fe grade also were took into account. The paper substantiates the optimal cut-off grade values of Fe associated with magnetite in the range of 12–14 %.
 The interval of the largest changes in reserves quantity with an increase is fixed for range of 12–18 %. Beyond this interval there is a minimal fluctuation of ore reserves quantity as a result of cut-off grade’s changes.
 In order to find optimal cut-off grade values using geostatistics and spatial modeling, it is necessary to follow the dynamics of reserves’ quantity changes depend on Fe cut-off grade, as well as to take into account average Fe grade fluctuations when changing cut-off grade.

Quantifying the criteria for classification of mineral resources and reserves through the estimation of block model uncertainty using geostatistical methods: a case study of Khoshoumi Uranium deposit in Yazd, Iran

ABSTRACT Investments and progress of mineral projects depend on the quantity (tonnage) and quality (grade) of mineral resources and reserves. This study examines the impact of various criteria used in the classification of mineral deposits or parameters defining these criteria. The data used in this study include the uranium assay analysis from 127 exploratory boreholes, which were then subjected to a three-directional variography after statistical studies to identify regional anisotropy. A grade block model was built using the optimal parameters of variograms and with the help of kriging estimator. Then, by using different methods of estimating the block model uncertainty including kriging estimation variance, block error estimation, kriging efficiency and slope of regression, classification of mineral reserves was carried out in accordance with the JORC standard code. Based on different cut-off grades, the tonnage and average grade were calculated and plotted. An innovative quantitative method based on the distribution function of the mentioned parameters and the fractal pattern of separation of populations was used for the classification of mineral reserves. The existence of the least difference between the use of standard and fractal patterns in the slope of regression method indicated less error and was a proof of more reliable results.

Effect of Cutoff Grade and Stripping Ratio on the Net Present Value for Hamama Gold Project, Eastern Desert, Egypt

This paper represents an attempt to examine the effects of Cutoff Grade (COG) and Stripping Ratio (SR) on the Net Present Value (NPV) for the proposed gold mine in Hamama area, hence to attain best operating condition corresponding to the optimum COG and SR in the proposed gold mine. Discount Cash Flow (DCF) model has been established to calculate NPV by taking the change in the COG and SR into account. This detects the effects of COG and SR on the NPV of this project. The actual production and cost data of Sukari Gold Mine (SGM) of Egypt have been taken as an indicator in creating DCF for the proposed gold mine where maximum NPV results proved the optimum COG and SR.

Simultaneous stochastic optimization of production sequence and dynamic cut-off grades in an open pit mining operation

An open pit mining operation is a complex system that constitutes several components or processes. An optimal production sequence that defines timing of extraction and a dynamic cut-off grade policy that defines the supply of materials from sources to destinations within the system are crucial to the success of an operation. In current practice, separate sequencing and cut-off grade models achieve these important milestones as part of strategic planning. This paper presents a mathematical model that derives the optimal extraction sequence and cut-off grade policy simultaneously considering grade uncertainty and stockpiling. A framework of genetic, maximum flow and cut-off grade algorithms solves this complex non-linear problem. An application of the method at realistic copper and gold mining operations reveals the value (up to 29% increase in discounted value) of stockpiling as well as risk quantification under uncertainty.

Application of meta-heuristic optimization algorithm to determine the optimal cutoff grade of open pit mines

The optimal cutoff grade leads to maximizing the profit or the net present value (NPV). One of the most important issues in open pit mining is cutoff grade optimization with regard to NPV maximization over the mine life. The most famous method that applied for cutoff grade optimization is the Lane methodology. Mining capacity, concentration plant capacity, and refining plant capacity are the three major parts of the abovementioned methodology and further, more time value of money and ore grade distribution are considered in Lane method. Repeated and cyclic calculations are the most disadvantages of lane methodology and therefore, in this research, the imperialist competitive algorithm (ICA) as a robust meta-heuristic optimization method has been applied to calculate the optimal cutoff grade. The accuracy of calculation was set to 0.001% and also the production of each unit and the NPV have been determined by ICA method. The optimum cutoff grades have been obtained from 0.232 to 0.135% in mine life time and NPV was calculated 37,750 billion Iranian Rials but the range of cutoff grades that calculated by Lane method was from 0.233 to 0.155% and NPV was determined 37,434 billion Iranian Rials. The results of this study showed that the determination of the optimum cutoff grade by the ICA has high accuracy and more speed of calculation in comparison with traditional lane method.

Determination of optimum cut-off grade of an open-pit metalliferous deposit under various limiting conditions using a linearly advancing algorithm derived from dynamic programming

In the process of planning an open-pit, the determination of optimum cut-off grade plays a vital role. The classical approach of Lane's algorithm yields infinitely many solutions when the metal price is very high and mining, milling and refining costs are low. This problem has been addressed through a new algorithm. This study deals with the optimization of cut-off grade of a real-life case study of an open-pit copper mine in India considering fixed annual production of mine, mill and refinery facilities. However, the optimization ignores uncertainty in input parameters. The optimization has been carried out with the objective of maximizing the discounted total profit in terms of Net Present Value (NPV). As the process of determination of optimum cut-off grade of the deposit is dependent on many parameters which can suitably be addressed using a linearly advancing algorithm derived from dynamic programming approach. Considering a precision of 0.01% in the grade interval, the optimum cut-off grades, the amount of metal produced per ton and the NPV have been evaluated. Accordingly, the optimum cut-off grade of the Malanjkhand copper deposit has been found to be 0.32% amounting to a maximum NPV of ₹ 12123 million. The calculation reveals that the life of mine is 37.5 years and the average mill head grade optimises to 1.12%. The results also reveal that the present value of net cash-flow increases in the initial years, reaches a maximum value at a certain mid-life time and then declines with the depletion of the reserve. The NPV finally reaches a zero value at the end of mine life corroborating the general trend as seen in other mining organisations.

Cobalt enrichment in a paleo-karstic bauxite deposit at Yunfeng, Guizhou Province, SW China

Cobalt can be enriched in a variety of different geologic settings, while it is mainly produced as a by-product of sediment-hosted stratiform Cu deposits and magmatic Ni-Cu deposits associated with mafic and ultramafic rocks. In this study, we report elevated Co concentrations in a paleo-karstic bauxite deposit at Yunfeng, Guizhou Province. Whole-rock chemical analyses indicate that Co is concentrated in carbonaceous ferruginous clay layers (167–962 ppm, average 383 ppm, n = 5) and siderite layers (47–439 ppm, average 213 ppm, n = 7) within the bauxite deposit. The positive correlation between Co and S, together with petrographic and EPMA analyses, suggests that Co occurs primarily as Co-rich/bearing sulfides/sulfoarsenides rather than cobaltiferous oxides/hydroxides as in most lateritic Ni-Co deposits. Many of the Co concentrations measured in this study are higher than the minimum grade (300 ppm) or cut-off grade (200 ppm) for economic exploitation of Co from sulfides or arsenides. Basing on these results, we put forward the scientific significance of Co enrichment in paleo-karstic environments and the potential importance of Co resources (as by-products of aluminum production) in bauxite deposits.

Investigation of the mechanism for selective flocculation process using natural iron ore tailings

A huge quantity of iron ore tailings was generated every year from the iron ore washing plants during beneficiation. These discarded tailings were stored in the tailing pond. Safe storage and handling of these tailings are a major concern to the management. Due to depletion of high-grade ore, the government of India had reduced the cut-off grade from 55 to 45% because of the shortage of the iron ore reserves. Ultrafine particles present in the tailings cannot be treated effectively by the conventional methods due to particle size limitations. For Indian iron ore, associated gangue mineral alumina is the major source which causes problems in the blast furnace. Removal of alumina from the iron ore of ultrafine size is a hill task. A selective flocculation approach was employed to the iron ore tailings which contain 50.98% of Fe (T) with 8.86% of Al2O3 assay. It was observed that, when applying a selective flocculation process, the concentrate contains more than 63.48% Fe (%), 2.5% Al2O3 with 31.196% recovery (%). The mechanism was investigated using zeta potential analysis, FTIR analysis, etc.

Dilution risk ranking in underground metal mines using Multi-Attributive Approximation area Comparison (MABAC)

The contamination of ores with wastes or materials of lower than the cut-off grade is referred to as dilution. Dilution is an undesirable phenomenon that, on one hand, reduces the product grade and, consequently, reduces the sales prices and, on the other hand, adds an extra cost to waste production. Therefore, studying and evaluating the dilution risk is important in mining, and especially in underground mining. In this work, using a powerful decision-making method, i.e. Multi-Attributive Approximation Area Comparison (MABAC), the dilution risk and ranking it in underground mines are assessed. For this purpose, the most important parameters affecting the dilution in 10 mines of the Venarch manganese mines are first identified and then weighed using the Fuzzy Delphi Analytical Hierarchy Analysis (FDAHP) method. Then using the MABAC method, the dilution risk score for each mine is estimated, and subsequently, various mines are ranked as the dilution risk. Then with the implementation of the Cavity Monitoring System (CMS) and measurement of the actual dilution values, the mines are ranked in dilution. The correct matching of the results of these two rankings indicates that the MABAC method is highly effective in the ranking of the risk. At the end, the risk ranking of the mines is done using the TOPSIS method, and the lack of full compliance with the results of this method with the actual values indicates that the MABAC method is preferable to the TOPSIS method.

Strategic planning of an underground mine with variable cut-off grades

We present a mixed-integer programming model for solving the long-term planning problem of an underground mine. This model, which establishes the sequence of mining for a horizon of 20 years, determines which lens of the geological model will be mined and in what order, while respecting the operational constraints. For each lens to be mined, a specific cut-off grade has to be selected to maximize the net present value. The choice of a cut-off grade affects the volume and the average grade of each lens, which increases the size of problems to be solved. To reduce the computation time, different acceleration strategies and a Fix-and-Optimize heuristic are proposed. Computational experiments on instances of different sizes are performed to (1) assess the quality of the solution found by each method and (2) present the impact of the variable cut-off grade.

A New Methodology Based on Hill of Value for Ore Reserve Selection in Long-Term Planning for Block Caving

The underground mining evolution for block cave mines in Chile and worldwide has made important strides in the last decades. Nonetheless, reserves determination in the initial stages of these types of projects—mainly for long-term planning—is not studied in as much detail as it should be, especially regarding the impact on the final value of the enterprise. Today, the first estimation of the size of a block cave mine, typically expressed in tons, tends to determine very large footprints and ore bodies. The resulting large-scale mine is obtained by applying the marginal cut-off grade (COG) to determine reserves. Yet, in many cases, it is possible to obtain an equal or higher benefit, extracting fewer reserves in less time, with a smaller active area, which significantly reduces the project’s uncertainty. To explore scenarios obtained by applying a higher marginal COG in the initial phases of the project, the Hill of Value methodology is used to estimate the net present value (NPV) in relation to the production rate and the COG. However, the application of this methodology considers certain simplifications that generate results which are not completely satisfactory in specific cases. This paper suggests an improvement of this method to obtain more reliable results regarding determination of a COG profile that will optimize the NPV of a block-cave project. The methodology was developed and applied in a massive polymetallic deposit with zinc, lead, and silver mineralization, corresponding to a real block caving project. The methodology provides NPV results that differ by approximately 15% in comparison to the real mine plan, while also being considerably simpler and faster to calculate. In summary, the proposed methodology provides a reasonable and fast procedure to estimate higher than marginal COG that increases the NPV of block cave mine projects.

Pre feasibility study in hydrometallurgical treatment of low-grade chalcopyrite ores from Sarcheshmeh copper mine

Chalcopyrite heap leaching is not yet a commercial reality, not just because of its lower recovery or slower kinetics, but rather, because of the economic impacts lower recovery and slower kinetics impose to the operating cost of the process. Considering the importance of the financial analysis on the economics of the operation, in this research, the economics of hydrometallurgical treatment of low-grade chalcopyrite deposit at Sarcheshmeh mine as a function of ore grade and extraction recovery were investigated. First, a brief history and theory of chalcopyrite ore leaching has been reviewed, showing that bio heap leaching at a possibly higher temperature with forced aeration is the only viable technique in treatment of low-grade chalcopyrite ores. In the economic feasibility study section, an operating cost estimate, capital cost estimate and economic analysis for a plant with 7000 tons per year copper cathode production capacity as a function of ore grades, acid consumption and heap leaching recoveries were investigated. Preliminary capital cost and operating cost estimates were made within two scenarios for a plant utilizing bio heap leaching, solvent extraction and electrowinning of low-grade chalcopyrite ore. The operating cost, for instance, was shown to be between US$5.99/kg to US$4.29/kg of copper cathode for extraction recoveries of 30% to 50% in a scenario where the construction of new SX and EW plants are required (Scenario 1). The operating cost was shown to reduce to US$5.36/kg to US$3.66/kg, for a similar recovery range, if the current SX and EW facility can absorb the bio heap leaching solution (Scenario 2). Using the operating cost data and the current copper selling price, the ore cut-off grade as a function of copper extraction efficiency was identified. The economic analysis showed that for an ore containing 0.28% copper, 7000 tons per year of copper cathode production requires a total investment of 38 million US dollar. The internal rate of return for such a plant was shown to vary between −2% to 27% for copper extraction efficiencies between 30% to 50% (Scenario 1). The sensitivity analysis of the similar plant showed that a copper selling price of US$5/kg, for instance, can even make the 50% copper extraction efficiency economically unacceptable for scenario 1.

An example of uraniferous leucogranites in the Rössing South-West deposit, Namibia

The southern Central Zone (sCZ) of the Neoproterozoic to early Palaeozoic Damara orogenic belt hosts significant uranium deposits in Namibia. Rössing South-West, a leucogranite-hosted uranium deposit in the sCZ is partitioned into two sections; north-easterly and south-westerly sections with the latter (termed mining licence 120, i.e. ML121) forming the locus of this investigation. The deposit lies within the vicinity and to the west of the Welwitschia lineament which served as a conduit for mineralized fluids along with the Rössing and Husab deposits. Mineralogy and major and trace element geochemistry of the uraniferous leucogranites in ML121 suggest they are S-type granites derived from a sedimentary source as evidenced by the presence of igneous phases of garnet and cordierite together. Microscope and electron microprobe results from 133 powdered, drill core and hand samples prove that the deposits host similar primary uranium mineralization (chiefly uraninite which mainly exist as independent uranium minerals) and similar secondary U mineralization. At Rössing-SW U minerals include uraninite, coffinite, pitchblende, betafite, uranophane, betauranophane, carnotite, gummite and might partially exist as Th isomorphs. Mineralization at all locales is associated with post-tectonic D and E-type sheeted leucogranites containing quartz, alkali-feldspar and variable amounts of plagioclase producing rocks of variable compositions from tonalite to alkali-feldspar granite. Total reserves calculated at a cut-off grade of 100 ppm were reported as 171 Mt of ore at 376 ppm for Rössing and 205 Mt of ore at 497 ppm for Husab (probable). The Rössing-SW orebody is open-ended however total inferred resources stand at 304.4 Mt of ore at 235 ppm while measured resources stand at 8830t ore at circa 231 ppm. A comparison of the geological parameters (uranium mineralogy, leucogranite petrology and geochemistry) suggests similar ore composition. Consequently, ore from Rössing-SW's ML121 area could be processed at existing metallurgical plants (such as at Rössing or Husab) with a probable increase in U3O8 yield.

X-ray-transmission based ore sorting at the San Rafael tin mine

San Rafael is the largest underground tin mining operation in the world. The main methods for processing the ore are gravity separation and flotation. In 2016 a new addition to the plant was an X-ray transmission (XRT)-based ore sorting island. The objective was to reject waste from a marginal development waste dump, and it is now also treating low grade material from the underground mine. XRT sorting discriminates particles on a planar projection of the density of matter attenuating X-ray radiation. Physical separation is achieved by means of an array of high speed air jets. The feed grade of approximately 0.6% tin is concentrated to 2.8% tin in the product at recovery of 90% in about 19% mass yield to product. This enriched product fraction from the sensor-based ore sorting plant feeds into the main plant.The plant, which is designed for 3600 tonnes per day, went into operation in 2016. The total capital expenditures of 24 M$ US were paid back within 4 months. The projected contribution to the production of refined tin for the year 2017 was 6000 tonnes. In summary, the positive impacts were:–Value added from previously sub-economic waste that can be mined with lower costs.–Increase of productivity in the main wet sections of the plant.–Reduction in cut-off grade and increase in reserves.–Reduction of environmental impacts.The paper describes the project from concept, through the development phase, including test work confirming feasibility, to a discussion of operational data and includes shared experiences from operation and maintenance.

The Occurrence and Concentration of Rare Earth Elements in Acid Mine Drainage and Treatment Byproducts. Part 2: Regional Survey of Northern and Central Appalachian Coal Basins

Many modern industries rely on rare earth elements (REEs) to produce products that are essential to both civil and defense applications. In a prior study (Vass et al., 2019), the authors showed that REE grades in acid mine drainage (AMD) and associated byproduct precipitates from AMD treatment (AMDp) warrant evaluation as a feedstock for REE production. The current work extends that effort through a broad survey of 141 AMD treatment sites in Northern and Central Appalachia. In this study, 185 raw AMD and 623 AMDp field samples were obtained and analyzed to assess the REE and major metal concentrations. Results show that an average of 282 μg/L and 724 g/tonne of REEs occur in AMD and AMDp respectively. Additionally, both basins contained similar distributions of REEs, and these distributions tended to favor heavy and critical REEs when compared with traditional REE ore deposits. Geospatial analysis identified a total resource of 340 tonnes stored at the 141 sites sampled in this study. While this analysis did not quantify the basin-wide REE inventory, it does indicate the impact that processing cut-off grades will have on the overall AMDp resource base.

A Sequential Optimization Model of Cut-off Grade and Project/Location Selection in Open Pit Mining

A Sequential Optimization Model of Cut-off Grade and Project/Location Selection in Open Pit Mining

Development of a bulk ore sorting model for sortability assessment

Bulk ore sorting (BOS) has the potential to reduce processing costs and improve mine economics. A factor that impedes its acceptance is the lack of a method to assess ore amenability to sorting. In this study, a fractal model of metal distribution was used to assess an ore’s bulk sortability. A BOS model was developed where metal distribution properties were characterised, optimum cut-off grade for sorter operation was determined, and economic potential of BOS was evaluated.For the developed model, the metal distribution within the ore deposits was recognised as a fractal structure. Two parameters were introduced, namely the grade factor and fractal dimension, to quantitatively characterise ore properties in terms of grade magnitude and heterogeneity. The mass balance of the sorter operation was modelled as a function of the characterised ore properties and the optimum cut-off grade was determined based on model calculations. The economic potential of BOS was evaluated in terms of the net smelter return and compared with that when no BOS was implemented.Based on the developed model, the bulk ore sortability of different ore properties was assessed with a hypothetical underground copper mine. The developed BOS model provided a powerful tool for ore sortability assessment and is expected to encourage academic research and industrial practices of BOS.

Simultaneous stochastic optimization of an open pit gold mining complex with supply and market uncertainty

ABSTRACTA mining complex can include multiple mines, stockpiles, waste dumps and processing facilities. Traditional optimization approaches are often based on sequential optimization of the various components in the mining complex leading to suboptimal solutions. They also do not account for uncertainty in critical inputs, resulting in misleading forecasts. This paper presents an application of a stochastic framework that simultaneously optimizes mining, destination and processing decisions for a multi-pit, multi-processor gold mining complex. The framework accounts for supply and market uncertainty via stochastic orebody and commodity price simulations as inputs to a unified optimization model. The case study notably assesses the impacts of integrating market uncertainty as input that influences all components of the production schedule. Additionally, cut-off grade decisions are determined by the simultaneous optimization process, considering material variability and operating constraints while reducing the number of a-priori decisions to be made. This approach generates solutions that capitalize on the synergies between extraction sequencing, cut-off grade optimization, blending and processing while managing and quantifying risk in strategic plans, which ultimately leads to more metal production and higher net present values.

Geology and mineralization of the Cu-rich Mumbwa district, a potential IOCG-type system at the eastern margin of the Pan-African Hook batholith, Zambia

The Mumbwa mineralized district is located approximately 200 km west of Lusaka, at the north-eastern margin of the Pan-African granitic Hook batholith. Polymetallic sulphide occurrences in the area have been known for hundreds of years, but more recent geophysical and geochemical investigations led to the discovery of a copper-rich hydrothermal system, mostly associated with late-stage syenite intrusions of the Hook batholith. The extent of the hydrothermal system is not known, but to date two main centres have been identified, the Sugar Loaf and Mutoya.Sulphide mineralization occurs along regional-scale lineaments, following a 25 km-long NNW-trending corridor. Mineralized host rocks are characterized by brecciation, often pervasively replaced by magnetite-hematite, and by strong metasomatism with multiple - and often superimposed - alteration cycles, from potassic, to carbonate, sericite-chlorite and amphibole-apatite-carbonate. Sulphur isotopes suggest that a mixture of magmatic and sedimentary-derived evaporitic fluids were critical in providing sulphur and metals. Late syenitic intrusions triggered the relevant hydrothermal circulation and favoured the mineralization processes.Diagrams plotting key element geochemistry and alteration indexes highlight vectors to alteration and mineralization and suggest that the sulphides preferably concentrated in rocks affected by hydrothermal iron oxides in association with sericite-chlorite alteration.At the Kitumba prospect (in the Sugar Loaf mineralized centre), granitic to syenitic bodies host a hypogene copper mineralization (mostly chalcopyrite), that was subsequently overprinted by pervasive and deep supergene mineralization (malachite, chalcocite, chalcosiderite, cuprite, digenite, chrysocolla, bornite, native copper). Supergene mineralization has been identified in boreholes to depths exceeding 700 m. Reserves at Kitumba are estimated at 27.9 Mt with an average grade of 2.2% copper at a 1.0% copper cut-off grade. Gold is present, although generally at low grades.In the Mutoya centre, metasedimentary rocks alternate with felsic intrusions. Two prospects have been identified, characterized by large areas of magnetite-hematite breccias hosting sulphide mineralization with predominantly pyrite and minor chalcopyrite.An affiliation to the iron oxide copper gold (IOCG) category is discussed. Many, but not all of the distinctive IOCG features, are present in the studied area.

Enrichment of critical elements (Nb-Ta-Zr-Hf-REE) within coal and host rocks from the Datanhao mine, Daqingshan Coalfield, northern China

This paper discusses the modes of occurrence of critical elements and their origins in the studied coal and associated rock samples (partings and roof strata) from the Datanhao coal mine, Daqingshan Coalfield, Inner Mongolia, northern China. The studied coals are enriched in trace elements including Zr, Hf, Th, Be, F, Zn, Ga, Nb, Mo, Cd, In, Sn, Ta, Hg, W, Pb, and rare earth elements and Y (REY). Zirconium, Nb, Ta, and Hf are largely associated with anatase in the studied coal and non-coal samples. The main carriers of REY, Th, and U in both coal and non-coal samples are Ca-bearing REE-phosphate minerals, most likely monazite, although U is partly associated with organic matter. Fluorine in the Datanhao coals is mainly associated with kaolinite.Most partings identified as volcanic ash-derived tonsteins from the Datanhao Mine exhibit negative Eu anomalies that, along with the common presence of equant-shaped euhedral volcanic quartz (beta-quartz), indicate a felsic volcanic source located in the Xing'an-Mongolia Orogenic Belt. Other probable sources of clastic material into the basin include the pre-Cambrian granites from the adjacent uplands, which may be responsible for the light rare earth element enrichment of the studied deposits, and associated metamorphic rocks from the adjacent uplands.Owing to acidic hydrothermal fluids, which are most likely related to the Yanshanian (Jurassic to Early Cretaceous) intrusive activity and/or low-temperature basinal waters circulating within the coal-bearing unit during the epigenetic stage, most of the coal benches from the Datanhao mine are also relatively enriched in middle rare earth elements. On the other hand, some coal and non-coal bench samples from the middle Datanhao section are enriched in heavy REE. This, along with the presence of abundant syngenetic or early diagenetic carbonate minerals, indicates deposition in an episodic alkaline environment, the origin of which is mostly probably attributed to evaporation and/or saline water inputs resembling a playa lake environment.As the concentrations of Zr, Hf, Nb, and Ta are all close to or higher than the respective industry cut-off grades or standards for these critical elements, the Datanhao coal seam has potential economic significance for these as an important by-product of the coal mining.