Ore Loss Research Articles

Gubici i razblaživanja u rudnoj žici br. 4 u rudniku Zletovo, Republika Makedonija

Zletovo mines have a tradition of exploration and exploitation of vein lead-zinc ores for almost a century. Ore losses and dilutions have always been imperative in production since traditional old methods of mining and low-productivity mineralization are used. In conditions of classical and sub-level method excavations used, the calculated ore losses in ore vein No. 4 are 13.5%, while at the level of all excavations in the Zletovo mines dilution averages at 10%. Ore dilution is also an important technical parameter and several possible variants were calculated. When analyzing the dilution that occurs during the preparation of the sub-level corridor with parameters such: different drop angle (45-60o), constant thickness of 1.47 m as the average vein thickness in the calculated ore reserves, width of the sub-level corridor of 1.57 m or to the width of the ore vein No. 4 were added 10 cm (left and right to 5 cm) as much as is taken in the calculation of the planned dilution and height of 2.5 m as suggested for this mining method, it can be noticed that the planned dilution during this method of mining ranges from 26.3% to 42.3%. In conditions of use of this underground method of excavation, parameters are selected that allow for the indicated lowering of the dilution. Namely, the thickness of the ore wire would be 1.47 m, the mining width would be 1.57 m, only 10 cm (left and right up to 5cm) to the thickness of the ore vein will be added, the height difference between the consecutive levels would be 7.5 m, dip angle of 45 to 60°, and with the excavation the whole ore vein would be covered in height. On the basis of these parameters, models were prepared in which the ore vein would have a different dip angle, from which the values for the planned ore dilution ranged from 6.7 to 7.8%, which is significantly lower than the average dilution in the Zletovo Mine.

ANALYSIS OF ORE LOSSES AND DILUTION FACTORS IN BAUXITE UNDERGROUND EXPLOITATION

<p>In this article are presented the analysis of ore losses in bauxite underground exploitation as well as the manner and possibility to increase recovery factor of ore deposit and exploitation with minimum of diluted ore with overburden. The largest losses of ore are the caracteristics of the mining process itself and the results of model studies of the ore losses and recovery for the various parameters of sublevel - transverse caving method are given in the article.</p>

Failure of hanging roofs in sublevel caving by shock collision and stress superposition

Hanging roofs or high hang-ups, a common problem in sublevel caving mining, usually result in a large ore loss and undermine mining safety. This paper analyzed the formation of a hanging roof and showed that increased confining pressure and reduced free surface were its main characteristics. In order to break down a hanging roof, a new method based on shock wave collision and stress superposition was developed. In this method, two blastholes containing multi-primer at different positions are simultaneously initiated at first. By doing this, a new free surface and a swell room can be created. After these holes are fired, a long delay time is given to the next blasthole so that the fragments from the first two-hole blasting have enough time to fall down. This new method was applied to three hanging roofs in one production area, and all of them were successfully broken down. Field inspection indicated that almost no damage was caused in the nearby drifts/tunnels due to the new method. In addition, the far field vibrations were found to be smaller than the maximum vibrations induced by some other blasts.

Control of Ore Loss and Dilution at AngloGold Ashanti, Iduapriem Mine using Blast Movement Monitoring System

Blast Movement Monitoring (BMM) system is a new method of determining material movement during blasting in order to minimise ore loss, dilution and sometimes misclassification. The BMM system was introduced at AngloGold Ashanti Iduapriem (AAIL) Mine in the first quarter of 2013 as a result of reconciliation challenges at the start of operation at the Ajopa Pit in the first quarter of 2012. Since the introduction, there has been improvement in reconciliation, but the cost implication became worth assessing because of dwindling gold price. The main objective of this paper, therefore, is to assess the benefits or otherwise of BMM system on blast induced movement at Iduapriem Mine. The study comprises data collection on BMM system at AAIL and its analysis, as well as cost and benefit analysis. From the BMM data analysis, it was observed that, the bottom flitch of the blasted material moved more than the top flitch in the horizontal direction while the reverse was the case for the vertical movement. The cost-benefit analysis from four shots analysed revealed that there was a benefit of $753 835 which translates into 650% return on investment. Thus, the use of the BMM system has positive financial impact on Iduapriem Mine. Continuous use of the system as a grade control practice has, therefore, been recommended for the Mine, especially with shots containing ore. Furthermore, a dedicated team for this task has been recommended to enhance efficiency. Finally, high precision GPS has been suggested to be added to the detector instrument to make surveying of pre-blast and post-blast BMM points easier and faster. Keywords : Blast Movement Monitoring System, Ore Loss, Dilution, Misclassification, Reconciliation

Control of Ore Loss and Dilution at AngloGold Ashanti, Iduapriem Mine using Blast Movement Monitoring System

Control of Ore Loss and Dilution at AngloGold Ashanti, Iduapriem Mine using Blast Movement Monitoring System

A study on the draw laws of caved ore and rock using the discrete element method

Isolated physical draw experiments are conducted to investigate the shape of the isolated extraction zone (IEZ) and its main influencing factors. After validating the reliability of using Particle Flow Code (PFC) for draw simulation, various numerical models are constructed to investigate the draw laws of caved ore and rock under multiple drawpoint conditions. The results show that particle size, drawpoint size and column height have negligible effects on the IEZ’s shape, which is mainly controlled by mass drawn, and that the ore loss ratio decreases with increasing drawpoint size and caved ore layer height and increases with increasing drawpoint spacing.

Characterisation and reduction of ironstone ore by CO gas

Ironstone ore can be a valuable source of iron and silicon for the production of silicomanganese and other alloys. This paper provides analyses of the chemical and phase composition of ironstone and information on the reduction of ironstone by carbon monoxide at temperatures in the range 800–1150°C. Ironstone was provided as crushed and a lumpy ore. Crushed ironstone ore contained higher Fe2O3 concentration (40.6 wt-%) and lower SiO2 content (44.3 wt-%) compared to the lumpy one (21.2 wt-% Fe2O3, 68.9 wt-% SiO2). The main phases in the ore detected by XRD and SEM/EDS analyses were haematite and quartz. Two major reactions were observed upon heating ironstone in CO atmosphere, namely; partial reduction of iron oxides and formation of fayalite. The rate of fayalite formation increased with increasing temperature. Ore porosity significantly decreased upon heating. Ore softening and partial melting started at 1100–1150°C with a significant negative effect on iron oxide reduction. The weight loss of the crushed ore increased with increasing temperature to 1000°C and decreased when the temperature increased further to 1150°C. The weight loss of lumpy ore decreased with increasing temperature from 1100 to 1150°C. Based on the analysis using LECO oxygen analyser, the degree of iron oxide reduction in the crushed ore was estimated to be 82.4% at 1000°C, 68.8% at 1100°C and 33.1% at 1150°C. The degree of iron oxide reduction in the lumpy ore was 79.5% at 1000°C, 82.7% at 1100°C and 47.2% at 1150°C. No metallic iron was detected by XRD in samples heated in CO atmosphere at 1150°C, although a small amount of metallic iron was observed in SEM/EDS analysis. Equilibrium phases in the reduction of ironstone ores by CO were calculated using MPE model and compared with experimental data, these calculations also provided useful data on behaviour of ironstone during reduction at different temperatures.

Monitoring ore loss and dilution for mine-to-mill integration in deep gold mines: A survey-based investigation

Monitoring ore loss and dilution for mine-to-mill integration in deep gold mines: A survey-based investigation

Blasting parameter optimization of medium-depth hole caving for steeply inclined thin veins

On the basis of the industrial experiment of medium-depth hole caving in Jinchanggouliang Gold Mine, the authers carried out the optimization research of hole pattern blasting parameters. ANSYS/LS-DYNA was used to make several schemes of numerical simulation. Then the distribution features of the blasting stress fields under different hole pattern parameters and the formation process of the fractured blasting regions under the constrained blasting effect of narrow vein were obtained. The results show that when the resistance line is between 0.8 and 1.2 m, under the same hole spacing, the effective stress peak of the central free surface decreases with the increasing resistance line; when the hole spacing is between 0.9 and 1.6 m, it increases with the rising hole spacing under the same resistance line. As the bore hole density coefficient increases, the stress increments slow down, and the ore loss and dilution aggravate, if the bore hole density coefficient is more than 1.5. Comparison of all the schemes displays that the 1.0 m×1.4 m hole pattern parameter is the best. After employing the optimization results for the field experiment and with the CMS evaluating the blasting effect, the actual blasting zone volume covers 91.8% of the designed volume. The blast, with sound effect, did not cause the top and bottom side wall orebody to cave.

Нормирование потерь и разубоживания медно-никелевых руд в системах разработки Талнахского и Октябрьского месторождений с закладкой выработанных пространств

Нормирование потерь и разубоживания медно-никелевых руд в системах разработки Талнахского и Октябрьского месторождений с закладкой выработанных пространств

Unplanned dilution and ore loss prediction in longhole stoping mines via multiple regression and artificial neural network analyses

In recent years, stoping methods have been magnified as an extraction strategy in underground hard rock mining. According to a report from Austrade (2013), in 2013 70% of underground metal mines in Australia utilized open stoping, sublevel stoping, various narrow stoping methods, and other types of stoping and caving methods to extract ore. In addition, 51% of underground metal production in Canada relies on open stoping methods (Pakalnis et al., 1996). A disadvantage of popular stoping methods is that many mines are severely affected by dilution problems. Pakalnis (1986) surveyed 15 open stope Canadian mines and concluded that 47% of the operations suffered from more than 20% dilution. Likewise, Henning and Mitri (2007) reported that approximately 40% of open stoping operations in Canada suffered from 10% to 20% dilution. Dilution can be defined as ‘the contamination of ore with lower grade material’, and it can be generally classified into two categories: planned and unplanned. Planned dilution, also referred to as primary or internal dilution, is contamination by low-grade material within the ore block; whereas unplanned dilution, also known as secondary or external dilution, is contamination by lower grade material exterior to the ore block. Both of these dilute the ore stream value. Ore loss can similarly be classified as planned and unplanned. Planned ore loss represents the ore-grade material that has been excluded from the mining block at the stope design stage, whereas unplanned ore loss is the part of the mining block that remains in the stopes after mining. This study includes unplanned dilution and ore loss, which can be attributed to as overand underbreak in underground stoping production. These phenomena can be divided into dynamic and quasi-static types; the quasistatic type occurs after blasting, while the dynamic type occurs immediately (Mandal and Singh, 2009). The dynamic overand underbreak types are the main interest of this study, and a new terminology, ‘uneven break’ (UB), is used to identify it. To extend the definition of dilution, UB can be defined as the tons of mined unplanned dilution (positive) or ore loss (negative) per ton of ore mined, expressed as a percentage.

Lead and zinc dust depositions from ore trains characterised using lead isotopic compositions.

This study investigates an unusual source of environmental lead contamination - the emission and deposition of lead and zinc concentrates along train lines into and out of Australia's oldest silver-lead-zinc mine at Broken Hill, Australia. Transport of lead and zinc ore concentrates from the Broken Hill mines has occurred for more than 125 years, during which time the majority was moved in uncovered rail wagons. A significant amount of ore was lost to the adjoining environments, resulting in soil immediately adjacent to train lines elevated with concentrations of lead (695 mg kg(-1)) and zinc (2230 mg kg(-1)). Concentrations of lead and zinc decreased away from the train line and also with depth shown in soil profiles. Lead isotopic compositions demonstrated the soil lead contained Broken Hill ore in increasing percentages closer to the train line, with up to 97% apportioned to the mined Broken Hill ore body. SEM examination showed ceiling dusts collected from houses along the train line were composed of unweathered galena particles, characteristic of the concentrate transported in the rail wagons. The loss of ore from the uncovered wagons has significantly extended the environmental footprint of contamination from local mining operations over an area extending hundreds of kilometres along each of the three train lines.

Blast-induced dynamic rock fracture in the surfaces of tunnels

Hanging roofs or high hang-ups, a common problem in sublevel caving mining, usually result in a large ore loss and undermine mining safety. This paper analyzed the formation of a hanging roof and showed that increased confining pressure and reduced free surface were its main characteristics. In order to break down a hanging roof, a new method based on shock wave collision and stress superposition was developed. In this method, two blastholes containing multi-primer at different positions are simultaneously initiated at first. By doing this, a new free surface and a swell room can be created. After these holes are fired, a long delay time is given to the next blasthole so that the fragments from the first two-hole blasting have enough time to fall down. This new method was applied to three hanging roofs in one production area, and all of them were successfully broken down. Field inspection indicated that almost no damage was caused in the nearby drifts/tunnels due to the new method. In addition, the far field vibrations were found to be smaller than the maximum vibrations induced by some other blasts.

Generating synthetic data for simulation modelling in iron ore

Simulation modelling is a practice commonly used in the mining industry to evaluate alternative process designs. Such modelling is typically undertaken as an optimisation study to increase the efficiencies, productivity and product quality of operating mines. In this situation real short-term grade variability data of extracted ore are available from production records as input data into the simulation. There is also a need for simulation modelling to be performed before mines are approved for construction to clarify the grade variability characteristics that can be expected from the operating mine and assist in the optimisation of the process design. In this situation no historical short-term grade variability data are available. To achieve meaningful and reliable results from a simulation it is necessary to have input data for the ore to be extracted from the pits, representative of the short-term grade variability that would be expected for the operating mine. This paper describes an example of a path taken to generate realistic input data. A method described as composite cut-off criterion was used to distinguish ore from waste which gave substantially greater recovered tonnage at target grade compared to the conventional quadrant cut-off grade criteria. The only data available for the project was resource model data in the form of kriged block models, which are known to underestimate true ore grade variability. To achieve realistic results from the simulation it was essential to increase this variability while maintaining the accurate average grades. Areas of certain deposits that were modelled using both kriging and conditional simulation estimation techniques were quantitatively compared to establish the comparative variance and the kriged data was modified to match the conditionally simulated variance. A realistic mining model was generated via a process of discretisation and regularisation of the resource blocks. Quantitative assessment demonstrated that this method adequately compensated for ore dilution and that adjustment for ore loss was not required due to an ore skin surrounding the edge blocks. The conditioned data were then used to generate a schedule of daily mine extraction, considering grade variability, tonnage, equipment constraints and extensive blended-in-blended-out pre-crusher stockpiles to feed into the process design simulations. For the pre-crusher stockpiles a number of alternative allocation criteria were examined for ore being extracted from the pits to identify the best method in achieving reduced variability through the daily scheduling system. The study concluded that a single analyte separation criterion produced acceptable variability with minimal complexity. The blending efficiency of manually stacked and reclaimed pre-crusher stockpiles was studied to determine a realistic blending efficiency within the pile. A recommended method of building and reclaiming was determined to give maximum blending efficiency. Finally, the data were used as input into process design simulation models; simulation from crusher feed to ship loading demonstrated that control of shipment grade variability was achievable and that the conditioning of the data delivered realistic results.

Peculiarities in Setting Norms of Extraction in Underground Ining of Diamond Ore

Methodological approach is considered in this article which refer to evaluation of reasonable ore loss and dilution in mineral extraction in underground mining of kimberlite ore deposits in mine “International” and “Mir” of OJSC “ALROSA” concerning to the of descending mining in slices and consolidating stowing in worked-out areas with mechanized (continuous) mining. This work shows us the condition of conformation loss and dilution in mining and also computation algorithm

Reconciliation principles for the mining industry

Reconciliation involves the collection of tonnage, grade (quality) and contained metal (product) data from disparate and hopefully independent sources. Examples are exploration data, production sampling data from blast holes or draw points, and process plant data. These data may be compared by means of ratios (factors). The F1 factor usually relates short term (ore control) model tonnages, grades and metal content to ore reserves depleted. The F2 factor usually relates received at mill (measured by the mill) tonnages, grades and metal content to delivered to mill production tonnages, grade and metal content. The F3 factor is F1×F2 and enables a comparison of a mine’s (measured by mine) ability to recover the tonnage, grade and metal content estimated in ore reserves. The F1 factor measures the accuracy of orebody knowledge in the ore reserves to the demarcation of ore and waste by ore control (short term model). The F1 factor may be used to check and calibrate the selectivity of mineral resource models and/or planned dilution assumed in transfer from mineral resources to ore reserves. The F2 factor enables a check on unplanned dilution entering the ore stream between ore control and the mill. By using the factors it is possible to calculate a monetary value on improvements in the accuracy of orebody knowledge, selectivity and the effects of dilution and ore loss. Reconciliation should be an implicit part of the mining process, and reconciliation targets should be a key performance indicator for well run mines.

Study of Ferrous Material Reduction Based on Thermal Reserve Zone of Modern Blast Furnace

Through analyzing and inspecting the raw materials conditions and process conditions that affect ferrous material reduction in the thermal reserve zone, the article indicates that for the three commonly used ferrous material of blast furnace, sinter, pellets and lump ore, sinter is easiest to reduce and lump ore is most difficult to reduce. And increasing of the size of ferrous material promote the reduction of the ferrous material slightly. With the increase of batch weight, weight loss of ore and coke decrease at first and then increase. With the increase of the ratio of coke/ore, the extent of reduction of ferrous material had not significantly improved.

A comparative study between sequential Gaussian simulation and kriging method grade modeling in open-pit mining

Grade estimation is very important in designing open pits. In the process of grade estimation, underestimation can result in loss of economic ore, whereas overestimation would unnecessarily increase stripping ratio. Normally, kriging method, which suffers from underestimation and/or overestimation due to smoothing effect, is used for grade estimation. To overcome drawbacks of the kriging method, more efficient techniques such as conditional simulation can be applied. In this paper, utilizing sequential Gaussian conditional simulation, grade models were constructed for Sungun copper deposit situated in the North West of Iran. According to the obtained results, it was observed that conditional simulation can effectively cope with the weakness of kriging method. Also, it was observed that as compared to the kriging method, grade distribution, resulted from the conditional simulation, is almost identical to that of the real exploration data. Accordingly, using conditional simulation, the amount of mineable ore was significantly increased, and also, average net present value as the mines’ most important economic indicator was improved by 40%.

Laboratory Test and Particle Flow Simulation of Silos Problem with Nonhomogeneous Materials

Underground mine caving may induce collapse of the ground during ore caving, particularly when there is a loose material on top of the mine. In the present paper, a laboratory test is performed to model this mining problem which is followed by a particle flow simulation to simulate the interaction and movement between the two materials. For this nonhomogeneous problem, an interesting columniform channel for the loose material is formed during the drawing in both the experiment tests and the numerical modeling. The formation of this channel greatly affects the efficiency of ore drawing and the stability of the mine caving. The numerical modeling can be used for the optimization of ore drawing, ore drawing management and the prediction of ore loss and dilution indexes. The importance of the moisture content on ore drawing process and the efficiency of ore drawing are also investigated by both experimental and numerical tests, and useful results are found from the present study.

Cavity 3D modeling and correlative techniques based on cavity monitoring

According to the mining method for Dongguashan Copper Mine and Tongkeng Mine in China, and with the help of the cavity monitoring system(CMS) and mining software Surpac, the 3D cavity models were established exactly. A series of correlative techniques for calculating stope over-excavation and under-excavation, stope dilution and ore loss rates, and the blasting design of the pillar with complicated irregular boundaries were developed. These techniques were applied in Dongguashan Copper Mine and Tongkeng Mine successfully. Using these techniques, the dilution rates of stopes 52-2#, 52-6#, 52-8# and 52-10# of Dongguashan Copper Mine are calculated to be 2.12%, 8.46%, 12.67% and 10.68%, respectively, and the ore loss rates of stopes 52-6# and 52-8# are 4.41% and 3.70%, severally. Furthermore, according to the design accomplished by the technique for a pillar of Tongkeng Mine with irregular boundary, the volume, total length of boreholes and the dynamite quantity of the pillar are computed to be 1.2 × 104 m3, 2.98 km and 10.97 t, correspondingly.