Ore Flow Research Articles

Analysing the flow of wet iron ore in an industrial transfer chute using discrete element method

Analysing the flow of wet iron ore in an industrial transfer chute using discrete element method

Study on the Macro-Fine Mechanical Behavior of Ore Flow Based on the Discrete Element Method

The mechanical behavior associated with the flow of ore-rock bulk materials is an important factor leading to the instability and failure of the shaft wall of the ore storage section in ore passes. It is of great significance for accurately understanding the stability failure characteristics of the shaft wall in the ore storage section in the ore-drawing process to understand the flow characteristics and internal mechanical transfer mechanism of ore-rock bulk. The flow characteristics, contact compactness, stress distribution characteristics, and contact force probability distribution of the ore-rock bulk are analyzed by the discrete element method, which realizes the quantitative characterization of the damage degree of ore-rock flow and reveals the damage mechanism of the shaft wall in the storage section of the ore pass. The results show that (1) in the process of ore-rock particle flow in the ore pass storage section, the macroscopic flow pattern of ore-rock particles changes from a “—” shape to a “V” shape, and the friction between ore-rock particles, particles, and the ore-pass wall is an important reason for the change of the macroscopic flow pattern; (2) the probability distribution of contact force strength between the particles decreases exponentially in the whole ore-drawing process, in which the strong force chains play a major role in the stability of the bulk system; and (3) the overpressure frequency and overpressure coefficient could be used to quantitatively characterize the wall damage degree under the action of ore-rock flow. The dynamic lateral pressure fluctuates periodically in exponential form and decreases, and the dynamic load formed by the ore-rock flow mainly acts on the lower part of the ore storage section.

Analysis of induced stress during construction and production stages of drawbells in block caving mines

Drawbells are large constructions that allow the flow of the broken ore at the production level within the drawpoints. The results of drawbell construction are crucial for a successful mine plan extraction in a block caving mine. Analysis and integration of all the topics related to a drawbell can improve the performance of the surrounding area of drawbells, particularly the damage associated to induced stress during the different stages of a block caving operation. The improvement of operational aspects related to the drawbells would decrease the risk of failure, particularly in deep mines subject to large stresses, which are more likely to experience sudden violent or progressive failure. A large-scale numerical model was developed to analyse different mining sectors using sub-models. It was found that the geotechnical response is highly correlated to the stress field, which also controlled the resulting seismicity. In a scale of a drawbell, the drawpoint drift roof and the bridge pillar between the drawbell and the undercutting level were found the most critical zones in the design. When geological structures are present, they can be activated in the construction at an earlier stage and, therefore, could easily become critical in the resulting rock mass damage.

Оперативное измерение горной массы в процессе погрузочно-доставочных работ

The article discusses an automated control system for underground mining of copper-nickel ores and the weight control system as a part of this system. The main functions of the weight control system are described, as well as the requirements towards this system, the principle of applying the proposed algorithms and the results of implementing this system at an existing mining operation. The experience of measuring the rock mass during loading and hauling operations is described in terms of operational management and control of actual quantitative and qualitative parameters of ore flow in the multistage process of the ore grade stabilization in underground mining. The obtained results help to solve the challenge of controlling the LHD bucket load while ensuring the required parameters and operating conditions for the following application scenarios: (1) control of the transported rock mass for each haul cycle with the accuracy of ±6%; (2) control of the transported rock mass by a particular LHD per shift with the accuracy not worse than 1% for 60 haul cycles per shift; (3) for the operations with high moisture content of the transported load, it is possible to account for the stuck material for each haul cycle; (4) no special requirements to the weighing process; (5) minimization of the operating costs for calibration and maintenance; (6) high reliability due to minimum amount of hardware; (7) no degradation of the method when using readings of the hydraulic system; (8) unification of the system. The accuracy and reliability of the data obtained gradually increases during the operation when the test measurements are made about once a month. The disadvantages include: (1) impossibility to use the metrological level for measurements; (2) dependence on the technical condition of the onboard hydraulic system; (3) partial dependence on the LHD mileage. A conclusion is made that the process of ore grade stabilization should be multistage, and the measurement of the rock mass during the loading and hauling operations is one of the mandatory methods for implementation of the geometallurgical tasks.

Multistage dynamic optimisation of ore flow for underground metal mines

ABSTRACT The purpose of transportation dispatching in underground mines is to achieve efficient connection and operation cycles between different stopes while ensuring efficient ore transportation from stopes to a mill. The transportation system of large underground mines is a typical complex transportation network with large-scale transportation equipment, which involves both continuous and batch transportation succession and the blending of ore with different grades. The equipment dispatching has an important impact on the ore flow rate, grade, and transportation costs. Therefore, the ore flow needs to be optimally controlled from the perspective of multistage dynamic ore blending. A new model is presented to optimise the ore transportation process considering the ore flow rate, grade, equipment, and transportation network constraints, which aims at minimising transportation costs. The model is verified through a case study of the Sanshandao gold mine in China.

A numerical sensitivity study – The effectiveness of RFID-based ore tracking through a simulated coarse ore stockpile and the impacts of key process variables

The ability to understand ore characteristics in real-time during mining processes is vital for ensuring product quality control. However, it is challenging to continuously track ore flow from the mine to the mill due to the blending of ore batches, especially within stockpiles. This paper presents a numerical study of copper ore tracking through a coarse ore stockpile. A discrete element model of a 3D stockpile was created using the EDEM software to evaluate the effectiveness of using RFID tags for ore tracking. To identify the primary variables and their effect on ore transport and tracking through the stockpile, a sensitivity study was conducted to investigate a range of process variables, such as ore size distribution, ore size range, RFID tag size, wall friction, the trajectory of charging particles and stockpile charging methods. The results show that the stockpile model is not sensitive to variables such as the ore size distribution, ore size range and RFID tag size, while wall friction, stockpile feed belt speed, segregation in the ore flow region and contact model have a significant effect on ore blending within the stockpile. It was found that the overall performance of RFID-based ore tracking through the stockpile is poor. For cases with only one or a few tags per ore batch the order in which the tags are read did not provide a good representation of the ore distribution for most scenarios This sensitivity study provides insights into new tracking strategies given the poor performance of RFID tracking shown by the simulation study.

Critical Issues of Ore Flow for the Raise Caving Method

Ore flow has been identified as one of the critical points of developing the novel mining method Raise Caving (RC). The focus of this contribution is on the key issues of ore-flow and on how to encounter them to enable a safe, efficient, and economic mining operation.In the de-stressing phase of RC, narrow, tabular de-stressing slots are developed via raises, only the blast swell is drawn, and hence they stay filled with blasted material at all times to support the hanging wall in order to prevent early caving and dilution ingress. To simultaneously enable a free surface at the top for blasting, the extracted amount from the bottom needs to be monitored consistently. Another point in the narrow de-stressing slots is to prevent hang-ups by an adequate slot thickness. Hang-ups in higher zones are especially critical as they are difficult to resolve and may lead to unnoticed hanging wall caving.In the following production phase, production stopes are developed in the de-stressed area behind the slots. During this phase, the stopes are always filled with blasted material as a support for the hanging wall. They are only drawn-empty at a later point after the stopes are fully established. The most important issue for production stopes is to prevent early dilution in order to extract the deposit economically. Additionally, the free surface needs to be prepared for upcoming blasts. To optimize the extraction, a uniform flow towards the draw-points needs to be created. The mentioned points can be addressed by a proper mine design and draw strategy. The parts of the mine design include the draw-point spacing, the draw-point position, and the draw-bell layout. Further on, the draw strategy must enable a uniform draw, guide the ore down the inclined stope, and prevent early dilution. The critical points mentioned in this contribution are approached by the R&D with empirical, numerical, and analytical means.

A Data-Driven Soft Sensor for Mass Flow Estimation

Transporting iron ore by conveyor belts is widely used in the mining industry. The measurement of the mass flow of ore is essential for equipment protection purposes, preventing the conveyor belts from being overloaded, and for operational control purposes, when accounting for the production of equipment during a period of time. The equipment most used in measuring the mass flow of ore are conveyor belt weighers installed on conveyor belts. As they present a high acquisition cost and require a specialized team for maintenance, the installation of these scales is limited to just a few points of a mineral exploration plant. The present work proposes the development of machine learning techniques to estimate the mass flow of ore in a conveyor belt that is not equipped with a belt weigher. The virtual sensors were designed using current, torque, and motor speed data from a conveyor belt and iron ore flow measurements from a belt weigher installed on a different conveyor. Two of the proposed virtual sensors were implemented in a programmable logic controller of a belt conveyor in a mining area, where it was possible to verify the performance of the virtual sensors in a real situation. As a result, the proposed virtual sensors were able to measure the ore flow with an acceptable error rate compared to a physical belt weigher. The accounting of the production of the proposed sensors also proved to be close to the total production accounted the physical belt weigher.

Flow characteristic evaluation of iron ore for design of bunkers and chutes with different liner materials

Powders and bulk solids have to be handled and stored in all industries, ranging from powders, food, and pharmaceutical substances to raw materials such as cement, coal, and iron ore, as well as dry materials such as fly ash and moist bulk solids such as filter cake and clay. All these materials must be transported, conveyed, or otherwise handled. Thus, the characterization of powders and bulk solids in terms of flow properties is critical. The objective of this paper is to establish the flow characteristics of typical Indian iron ore for the design of test rig bunkers and chutes at different moisture levels.In this paper, the effect of moisture content on the iron ore's flow properties and its interaction with various liner materials is studied. Experimental tests were carried out for various moisture levels to determine the critical levels of moisture which adversely affecting the flow properties of bulk solids. A Jenike ring shear tester (RST) is used to find flow properties like bulk density, wall yield locus, internal friction angle, and wall friction angle of iron ore when it is interacting with different liner materials, i.e. SS 304 2B, Hardox400, Sailhard, and Chromium carbide. The results shows that 11.9% is the critical moisture level. Further, based on this, conical hopper half angle and critical opening size are evaluated for the design of mass flow bunkers and chutes.

Conceptual structure of on-line information and control system toward stabilization of ore flow quality

Underground mineral mining operations in the Norilsk Regions currently involve some essential changes connected with the requirement to maintain the production output at the wanted level and at demandable safety. In the meanwhile, the quality characteristics of minerals produced gradually worsen. In such situation, it is necessary to find a cardinally new approach to improving the crude ore quality by stabilizing composition of ore flow in the course of mining. The article discusses stabilization of ore composition in underground mines via modernization of information and control systems as a case-study of copper–nickel ore deposits in the Norilsk Region. The conceptual structure of the information and control system aimed at the ore flow quality stabilization is described. Such information and control system structure for the ore flow quality stabilization should provide all production control units with prompt and reliable data on the ore quality and its stability both for ore in situ and produced. The flowchart of the information acquisition, transfer and processing with the subsequent elaboration of a plan of strategic and tactical actions is critical and can, in the long view, become a mighty ore flow stabilizer capable effectively and considerably reduce variability of produced ore composition in the overall ore flow in a mine. The developed package of managerial, engineering and production activities makes the ore flow quality stabilization a controllable process. Its implementation allows enhancing technological efficiency not less than by 2 times, which can greatly improve performance in the whole mining and metallurgy sector.

Discrete element approach to determining rock mass pressure on ore pass walls

A critical safety factor of ore pass walls is the correct evaluation of rock flow pressure on the walls at the design stage. This study uses the discrete element method to determine load of rock flow on the ore pass walls. This method is the most effective in modeling ore flow through a trapdoor. On the other hand, modeling of each discrete particle can create an illusion that the model automatically takes into account all typical phenomena of granular medium. From this point of view, the method of discrete elements can be discredited in practice. Therefore, it is necessary to describe the methodology of constructing and correcting the discrete element and finite element models of ore passes. At the first stage, the grain size distribution of rock flow is analyzed, and the representative sample volume is determined. At the second stage, the shear tests are performed at the particle–particle and particle–ore pass wall contacts. It is required to implement both tests as the difference between internal and external friction angles can be assumed to be the cause of bridging (a silo phenomenon). At the third stage, due to essentially different kinematics of shearing andconical pile formation, the calibration criterion is chosen to be the angle of repose. The fourth stage is the bridging modeling and comparison of the model data with the analytical results. This stage is only limited to the numerical modeling as there are yet no fully developed techniques to reconstruct bridging in ore passes on a laboratory scale. At the fifth stage, the numerical experiments on filling an ore pass and on ore outflow from it are carried out. The results are transferred to a finite element method program.

Feasibility of Broken Ore Flow Simulation in Block Caving Mining Method Using Attribute Stochastic Medium Theory

In this paper, to reveal the flow characteristics of broken mineral-rock of block caving, we present the Attribute Stochastic Medium Theory that combines an attribute block model with stochastic medium theory. An attribute block model was established to fit discrete target regions. A void transfer model and data structure were established based on stochastic medium theory. Our key contribution is that we propose Attribute Stochastic Medium Theory and present the concept of draw-out index and block fragmentation index. It can be used to analyze the flow characteristics of rock block under different drawing heights and different fragmentation conditions. We implement the flow algorithm and simulation with C++ programming. The results show that mineral elemental grade information of the ore-drawing body was obtained, and when the block fragmentation index remains unchanged, with the increase of the draw-out index, the ore-drawing ellipsoid develops gradually, the eccentricity increases gradually, and the average depth of the depression increases gradually. In the isolated extraction zone (IEZ), the length of the long half-axis of the IEZ increases linearly with the increase of the ore-drawing height. But the length of the short half-axis and the eccentricity of the IEZ increase nonlinearly with the increase of the ore-drawing height, showing a general power exponential relationship. Under the condition of constant draw-out index, with an increase of the block index, the eccentricity of the ellipsoid decreases. This method could obtain the properties and flow characteristics of caving ore and rock. Combined with in situ test of ore drawing. This method could provide guidance for the design of ore drawing bottom structure and ore drawing plan.

Safe and effective methods for mining thin tilt and steeply dipping deposits with ore drawing via mud flow

For mining of thin (1–3m) tilt (15–45°) ore bodies, it is recommended to use the mining method with induced mud–water–stone flows to deliver broken ore up-dip the bodies in combination with scraper handling of ore along the strike and water jet washing of ore when forming columnar pillars, including underhand ore cutting, with division of blocks into many long stopes along the block strike, heading of one or two tilted accumulation and haulage rooms to be close-looped with the long stopes, scraping of broken ore to the tilt accumulation and haulage rooms and mud flow of ore along these rooms. This method can increase the stoping capacity as per the number of stopes in a block: for example, in a 160 m wide, only two tilt rooms are required to be headed between levels. The artificial mud flows in mining (or re-mining) of thin and steeply dipping ore bodies which have their girtwise bottom boundary skewed at 15–45 °, are no less effective. For the purpose of mining (re-mining) of such reserves, it is proposed to use a process flowsheet as follows: broken ore flows under gravity to the lower part of the extraction block and, then, along the tilted bottom of the block, it goes down under the action of gravity and energy of water flow in the mode of the mud–water–stone flow to the ore intake room on this level. In this case, as against mechanical haulage, the mud flow of broken ore essentially enhances the ore production output owing to the high capacity of the mud flow, and greatly reduces the scope of the preparatory and actual mining operations connected with the block bottom formation.The study was supported in the framework of the Target Financing Program of the Ministry of Education and Science of the Republic of Kazakhstan, Program No. 2018/ВR05236712.

Prediction of ore flow quality in a potash mine with regard to the ore face-to-shaft haulage logistics

The industrial know-how, analytical estimation and special experimentation proves that reduction in quality variation of the ore feed for processing can essentially raise productivity and improve final product quality at cheapening of the production at the same time. In pota sh production, the ore quality stabilization by the potassium content criterion enables a high economic profit owing to the increased recovery of the useful component, reduced consumption of chemical agents, saving of power and fuel, decreased losses of KCl with tailings, deloading of salt dumps and tailings ponds and, finally, the environmental destressing. Alongside with the technological blending of ore flow (reclaiming rooms, reservoirs, warehouses, etc.), there are potentially much cheaper managerial approaches. The quality control method includes the use of certain data acquisition, transfer and interpretation facilities arranged underground, relevant software support, as well as control units to operate the mine logistics. At the present time, the level of automation at Belaruskali meets all requirements imposed on the quality control of ore flow to outlet shaftAt the Mining Department of the Belarusian National Technical University, the service simulation procedure is developed for mine faces with various heading and cutting machines in specific geological conditions (mineral seam structure, mineral quality) and geotechnical conditions (seam thickness, cutting head width, face advance velocity, mining flowsheet, downtime duration, etc.).

Visualization and Assessment of Hang-Up Phenomena Using Vertical Transparent Ore-Pass Models

Limestone is one of the most important mineral resources, and it is only one mineral that can be fully supplied by domestic producers. Generally, a certain amount of ores is stored in the ore passes temporally after blasting excavation, and extraction is carried out from the bottom of the ore pass. However, the hang-up phenomena in the ore passes sometimes occurred and some cases are recently reported. Once the hang-up phenomena in the ore passes occur, it will cause serious problems. In this study, ore flow experiments in the vertical ore passes were conducted using ore pass models which was composed of transparent acrylic tubes, and the conditions of hang-ups were discussed. Since the ore passes were assembled with transparent tubes, it was also possible to observe the hang-up phenomenon directly. To discuss the effect of cross-sectional shapes of ore passes, two kinds of ore-passes, that is, circular and square shapes of cross-sections, are prepared. Using various sizes of ores, the relation between ore size and cross-sectional area was also discussed. It was found that the hang-up phenomenon almost did not occur when the ratio of ore pass size to the mean grain size of ores exceeds the value of 5. It was also found that the circular-shaped ore passes were a little preferable to avoid ore pass hang-ups compared with the square ore pass. The same procedure was applied to the mixed ores which two types of ores with different mean diameters are mixed. In this case, also, the results were almost the same as the results obtained by single-size ores. 3D-DEM analysis was also conducted, and the validity of the experiments was discussed.

Crusher to Mill Transportation Time Calculation—The Aitik Case

Comminution is a major contributor to the production costs in a mining operation. Therefore, process optimization in comminution can significantly improve cost efficiency. The mine-to-mill concept can be utilized to optimize the comminution chain from blasting to grinding. In order to evaluate the mill performance of the ore from a specific location of the deposit, a direct link needs to be established between the mill performance and the place of origin in the mine. Today, technology enables the accurate positioning of drilling, loading, and dumping points in the mine, making the ore flow between loading and crushing more transparent. However, the material flow from the crusher to the mill is not yet fully understood and monitored. This paper presents the development of an ore transportation model, based on the virtual silo concept, between the crusher and the mill for Boliden’s Aitik mine in northern Sweden. The proposed model helps to establish a link between in situ ore location and mill performance. Two transportation time calculations are used, one based on mass balance, and one based on momentary values. Historical data are used to test the capabilities of the model and the results are compared with the transportation time calculated from the mean capacity values, commonly used in previous studies to connect mill parameters with in situ ore location. The comparison of the results show that the mean parameter-based values can be as much as 50% lower than the transportation times, even in normal operation. In the tested times, the transportation time based on momentary values systematically underestimated the cumulated times. The developed model will also serve as a starting point to analyze the effect of geotechnical parameters, in addition to drill and blast design, on the mill performance of the blasted ore.

Применение численного и физического моделирования при проектировании конструкции рентгенолюминесцентного сепаратора, предназначенного для разделения руд, содержащих люминесцирующие минералы

The paper demonstrates the application of numerical and physical modeling to justify the design of the X-ray fluorescence separator’s material handling system. The Rocky DEM software package is a numerical modeling tool that uses the discrete element method as a mathematical apparatus. In order to increase the efficiency of the X-ray luminescence separation, the authors suggest including an additional element in the separator’s material handling system, i.e., a drum spreader that combines a handling device and an actuating mechanism. It was found out that the best loading of the drum spreader cells, in which the number of several pieces in one cell is reduced by at least 15%, is provided by a Vibrating feeder conveyor with a triangular cross-section of the profiled part of the tray compared with the tray of parabolic cross-section. In addition, the triangular section provides a double decrease in the number of pieces with rotational movement around their axes and, accordingly, an increase of at least 5% in the average velocity of the ore flow movement along the tray. The simulation of the material handling system has shown the need to reduce the height of the end partition of the drum spreader between the cells to 45 mm, which eliminates the collision of ore pieces with the partition and subsequently, their movement in the direction of rotation of the drum spreader on its outer surface, as well as the unpredictable escape of the ore pieces beyond the working space of the separator.

Performance Analysis of a Silo-SlideGate-Feeder System to Regulate the Ore Flow by DEM Simulation

Performance Analysis of a Silo-SlideGate-Feeder System to Regulate the Ore Flow by DEM Simulation

Informational aspectsatmodel of power consumption by main drainage facilities of iron-ore mining enterprises

The work investigates into variable informational approaches to modeling power consumption by main drainage facilities of ore mining enterprises with underground mining method. Methodological recommendations for using the models are also designed. The research deals with general methodological approaches to model formation with both power consumption indices fordrainage facilities and corresponding costs. Logistics of model formationis substantiated, namely,combination of classic multifactor regression modeling with modern digital modeling methods –automated control systems used for drainage facilities.Principles of building fuzzy logic controllers and algorithms of their functioning under multichannel control are determined in detail. Theimproved fuzzy logic-based variant is proposed and combined,with correlation analysis,to provide the basis for developing algorithms of the automated control systemsof electric power consumption. There is an example of developinga “road map”for implementinga generalized algorithm forautomated control systemspower flowsfor two current cases –a selective tariff with limiteddaily contract-based powerconsumption and that witha variable tariff.It is established that application of the two-rate hourly tariff with its conditional distribution (Night/Peak) instead of thethree-ratetariff(Night/Half-Peak/Peak) on a single-use basis leads to a thirteen percentincrease ofdailypowercostswith a single-channel controloftheore flow and a sevenpercent increase withtwo-channel control(ore flow and drainage simultaneously). The use of fuzzylogiccontrollers enables minimizing these losses.

ASSESSMENT OF THE COMPLEXITY OF OCCURRENCE AND GEOLOGICAL VARIABILITY OF THE QUALITY OF HIGH-GRADE ORES DURING THE DEVELOPMENT OF THE C-2 DEPOSIT

The work is devoted to a very topical issue - predicting quality indicators in underground mining of ore deposits. In this work, the conditions and ways of improving the quality of ores during mining were studied on the example of deposits of rich ores in the northern flanks of the Talnakh and Oktyabrsky deposits of Talnakh. The studies were carried out in specific conditions at the mining enterprises of the Polar Division of the Public Joint Stock Company Mining and Metallurgical Company Norilsk Nickel.
 The northern deposits of the Talnakhskoye deposit represent the main prospect for replenishing the retired production capacities for the extraction of high-grade ores. The significant heterogeneity of the distribution of the metal content in industrial reserves of rich copper-nickel ores is the primary cause of high fluctuations in the quality of ore flow, which requires the use of the most advanced mining technologies to control the quality of ores during extraction.
 The process of forming the required quality level of mined ores at the mines of the Polar Division of PJSC MMC Norilsk Nickel is of paramount importance. However, during the development of deposits of «rich» ores in the ore stream «mine - processing plant», significant fluctuations in the quality of the ore mass are formed, which lead to losses of metals in the process of concentration and during metallurgical redistribution, thereby reducing the economic efficiency of the entire mining and metallurgical complex, as determines the relevance of the work.