Ore Grade Research Articles

ПОСТРОЕНИЕ И СРАВНЕНИЕ РЕГРЕССИОНЫХ МОДЕЛЕЙ ОБОГАЩЕНИЯ ЗОЛОТОСОДЕРЖАЩЕГО СЫРЬЯ В ЦЕНТРОБЕЖНОЙ ОТСАДОЧНОЙ МАШИНЕ

Decreasing ore grades is a common challenge for every gold mining country in the world. Deposits of low-grade and complex ores are increasingly brought into production. These ores are typically treated by hydrometallurgical methods, for example, heap leaching. Meanwhile, the use of cyanide and its alternatives poses a risk for the environment. Thus, the development of gravity methods including jigging in a centrifugal-field is becoming an attractive option of low-grade and complex ore processing. Two mathematical models have been developed using the regression method to predict grade and recovery characteristics of the products of a centrifugal jigging machine (CJM) with variable process parameters including jig chamber rotational speed, pulsation frequency and vibration amplitude of a movable cone, underscreen-water flow rate. The models are based on the results of the field trials of a pilot centrifugal jigging machine designed by JSC Irgiredmet at existing gold-processing plants. Mathematical modelling provided a means of the process parameters ranking according to their impact on the separation process. A model has been identified that ensures a more accurate prediction of the separation process variables (metal recovery in concentrate) when the CJM's adjustable parameters are changed. The object of the study is the centrifugal jigging method of gold-bearing ore separation. The scope of the study is mathematical modelling of gold-bearing ore separation using CJM. The objective of the study is the determination and ranking of the CJM's process parameters according to their impact on the separation process, identification of a model that ensures a more accurate prediction of the separation process variables. The methodology of the study involves finding the correlation between gold grade/gold recovery into the separation products and the CJM's adjustable parameters. The method of the study is regression analysis

DETERMINING A RESILIENT STOPE BOUNDARY FOR UNDERGROUND MASS MINING PROJECTS

Uncertainty-based stope boundary optimization is a complex part of underground mine planning, especially in mass mining projects and notably block caving. Besides, grade variation and grade uncertainty are significant sources of error in mining projects. This paper presents a procedure to determine a resilient block-cave stope boundary considering the ore grade uncertainties. The procedure applies the floating stope algorithm, the maximum upside/minimum downside, and the value at risk for design evaluation. The floating stope algorithm is customized for block caving and is used to determine the stope boundary over some simulated grade models. The idea fits into a multi-criteria decision-making problem. Finally, the most resilient stope boundary is selected by considering several criteria and the TOPSIS method. According to the results, the resilient stope boundary covers an area where the mineable reserve is 977 Mt with an average copper grade of 0.51%.

The Union's Knowledge Strategies to Reach Success in the Implementation of Remote Operating Centers (COR)

Current conditions in metal mining, increasing operating costs, lower ore grades, and deeper deposits, make it necessary to take technological breaks to allow for high operating and production efficiencies. In Chile, there are integrated operations centers at the project level. The implementation of state-of-the-art technology has encountered problems such as the lack of a business perspective co-constructed in a political-technical system that breaks with the rigidity of the usual criteria and practices. The resistance to the redistribution of power so as not to perceive these centers as an operational anomaly to overcome the preference to operate manually is generating doubt of their real contribution of value. A transformation cannot be imposed but must be co-created. The knowledge of the trade union networks opens to the company culture possibilities of action that, in the face of a paradigmatic change, emerge to constitute value. This work shows the knowledge strategies to turn unions into cognitive assets to achieve success in the implementation of COR.

Overall Dynamic Optimization of Metal Mine Technical Indicators Considering Spatial Distribution of Ore Grade Using AADE

In optimizing the production of a metal mine, either the overall dynamic relations between technical indicators or the spatial distribution of the ore grade are usually considered, but few studies have considered both factors together. These two factors in combination have a greater effect on the optimization of mine production in terms of economic benefit and resource utilization than they do individually. We proposed an overall dynamic optimization model of technical indicators of metal mine production that considers the spatial distribution of the ore grade to better optimize the technical indicators and improve sustainable development of mineral resources. We incorporated an adaptive mutation strategy and adaptive control parameters into a differential evolution algorithm (AADE) in order to overcome the drawbacks of the differential evolution algorithm in solving this optimization model. The adaptive mutation strategy and adaptive control parameters were used to increase the rate of convergence and improve the search for a global maximum. To assess the performance of AADE, we used a real case and four test functions (the Sphere, Griewank, Rastrigin and Rosenbrock functions) in tests that compared AADE with a standard genetic algorithm, a standard differential evolution algorithm and the recently developed adaptive differential evolution algorithm. The results indicate that the optimization model we created is better aligned with mine production processes than current optimization models. In optimizing the technical indicators of metal mine production to maximize economic benefits, AADE performed significantly better than the other three algorithms tested in terms of convergence rate and global search ability.

Computational Cut-Off Grade Modeling: A Review

An entry into the mining profession is associated with many sectors that affect the environment, economy, and livelihood. Here, we have concentrated on the ore grade obtained from the extraction of the mining region. These ore-grade materials have limited on the mining region. Still, demand increases day by day-also affects the ore-grade level of materials as the supply situation. So, we have reviewed computational-based research on cut-off grade modeling techniques.

Stochastic Final Pit Limits: An Efficient Frontier Analysis under Geological Uncertainty in the Open-Pit Mining Industry

In the context of planning the exploitation of an open-pit mine, the final pit limit problem consists of finding the volume to be extracted so that it maximizes the total profit of exploitation subject to overall slope angles to keep pit walls stable. To address this problem, the ore deposit is discretized as a block model, and efficient algorithms are used to find the optimal final pit. However, this methodology assumes a deterministic scenario, i.e., it does not consider that information, such as ore grades, is subject to several sources of uncertainty. This paper presents a model based on stochastic programming, seeking a balance between conflicting objectives: on the one hand, it maximizes the expected value of the open-pit mining business and simultaneously minimizes the risk of losses, measured as conditional value at risk, associated with the uncertainty in the estimation of the mineral content found in the deposit, which is characterized by a set of conditional simulations. This allows generating a set of optimal solutions in the expected return vs. risk space, forming the Pareto front or efficient frontier of final pit alternatives under geological uncertainty. In addition, some criteria are proposed that can be used by the decision maker of the mining company to choose which final pit best fits the return/risk trade off according to its objectives. This methodology was applied on a real case study, making a comparison with other proposals in the literature. The results show that our proposal better manages the relationship in controlling the risk of suffering economic losses without renouncing high expected profit.

Properties governing the flow of solution through crushed ore for heap leaching

Heap leaching of low grade ores and waste rock is often limited by the hydrology of the bed, which determines the rate of dissolution of the target mineral. The lead author has performed physical and hydraulic testing of a large number of ore samples considered for heap leaching. The data was reviewed to develop relationships between the hydrology and the physical properties of the ore. Compressibility of the agglomerates under load was found to increase with silt + clay (−75 μm) content as high contents of silt and clay result in the destruction of porosity under load. The residual moisture held up in the bed after draining under gravity was found to be proportional to the surface area calculated from the PSD, assuming the bed is a collection of spheres. The residual moisture was also proportional to the sand content (−4.75 mm), as a result of the domination of capillary forces over gravity forces at lower particle diameters and smaller interstitial spaces. The pressure drop versus flow relationship during saturated flow was modelled with a modified form of the Carman-Kozeny equation, whereby the particle radius is replaced with a hydraulic radius. The ratio between the experimentally determined hydraulic radius and the hydraulic radius calculated from the PSD surface area was used to calculate the tortuosity. Since the minimum particle size of the PSD is not exactly known, minimum diameters of 0.002 mm, 0.02 mm and 0.2 mm were used to calculate the PSD surface area. A value of 0.2 mm was found to provide the most physically realistic tortuosity values of between 1.48 and 4.44.

Lexicographic goal programming approach for a short-term mining planning problem

This article addresses a short-term mining planning problem. There are four objectives to be minimized: the deviations in grades and ore proportion in particle size ranges of the plant goals, the deviation in the waste mass to achieve the stripping rate, and the number of truck trips between mining fronts and discharges. The problem was solved through the lexicographical goal programming (LGP) method, which generates solutions that can guarantee a more comprehensive analysis of the decision-making process. The LGP method was tested by using several scenarios of a Brazilian mining company. These scenarios differ in the number of excavators and the tolerances concerning meeting the plants' ore grades. In the results, the impact on the values of the other objectives is analysed of varying the number of excavators and the tolerances in the plants' grade targets.

Modern trends of technological advancement in iron ore processing

The authors discuss evolution of technologies and procedures in iron ore processing. It is emphasized that an iron ore treatment approach is governed by the type and nature of dissemination of metallic and nonmetallic minerals. Iron ore is mostly processed using magnetic, magnetic–gravity or magnetic–flotation separation. High grade ore with the iron content of 60–63 % is utilized without dressing, immediately after crushing and size grading. Magnetic and flotation circuits are used in processing of the most rebellious and finely disseminated low-grade ore. The ore pretreatment technologies feature the trends of introduction of press–rollers, which reduces energy inputs by 10–30 % as compared with the semi autogenous grinding. The essential improvement of size grading efficiency is reached via inclusion of fine sifting in the grinding circuits. Due to persistently growing demand for high-quality concentrate, fine sifting is also included in the finishing processing of rough concentrates. One of the methods to produce ‘super concentrates’ is the reverse cation flotation of rough iron concentrates using collectors composed of mono-, di- and ether amines, as well as their mixtures, including alcohols. The need to dress ROM hematite ore and to after-treat magnetic separation tailings of magnetite ore initiated engineering, manufacturing and commercial-scale introduction of high-gradient and highduty magnetic separators based on permanent rare earth magnets with the field density to 1.7 T. These machines have much smaller weight and consume much less energy than the high-gradient separators based on electromagnets. The promising method for hematite ore treatment is the reverse cation flotation. The use of the described processes, technologies and equipment allows production of concentrates with the iron content higher than 70 % and the silicon content less than 2 % at the iron recovery more than 90 %.

The influence of ore grade decline on energy consumption and GhG emissions: The case of gold

With the rush of metal consumption in the last decades and the expected raw material demand driven by the clean and digital transition, a growing concern has emerged about the decline of ore grades. Research of the effect of ore grade decline on energy consumption during the processing of metals has conventionally been addressed using historical data and LCA analyses. This paper provides another approach using a computational model developed with specialized software, HSC Chemistry, to analyse this relationship using gold as a case study. Gold was selected as it is a precious metal widely used in various applications, from jewellery to electronic circuits and will be key for digitalizing the economy. Considering all mineral processing stages, it was verified that the specific energy and associated environmental impact would experience exponential growth as ore grade in the mines decreases. As one of the most energy intensive stages is comminution, fuelled by electricity, the associated environmental impact is very much dependent on the electricity mix of the producing country. This approach allows for an evaluation of the future production's environmental impact for gold.

In-situ analysis of the Al-Fe-Mn-Cu oxide oxygen carrier for chemical looping applications

A novel Al-Fe-Mn-Cu oxide oxygen carrier, termed Gen3, was developed by NETL and prepared using natural ore and pigment grade materials. Gen3 was subjected to 10 cycles of reduction-oxidation (redox) through confocal laser scanning microscopy (CLSM) and thermogravimetric analysis (TGA), separately. TGA results indicated that Gen3 shows promise as an oxygen carrier, repeatably lending approximately 6% of its mass to oxygen carrying capacity. CLSM characterization led to the identification of different swelling behaviors among particles of ‘smooth’ (spinel-S) vs. ‘rough’ (spinel-R) surface morphologies, labeled based on appearance before redox cycling. Spinel-R particles exhibited homogeneous chemistry and porosity. Spinel-S particles showed much more localized porosity, specific to high-Cu areas. Gen3 particle volume increased 60% for spinel-S particles and 30% for spinel-R particles over the course of 10 redox cycles. All conditions showed some degree of separation of the complex Al-Fe-Mn-Cu spinel. Primary observed phases included Al-rich spinel, Fe-rich spinel, and Cu/CuO. Al-rich spinel and Cu/CuO in exposed Gen3 at times formed a lamellar structure of alternating Al-rich and Cu-rich layers in exposed Gen3 near areas rich in Cu. An additional Si-O-K-type phase was also observed that likely arose from the impurities involved in pigment grade materials and natural ores. Segregation increased with level of exposure. Si-rich regions and Fe-rich spinels showed extremely low porosity; a more evenly mixed Al-Fe-Mn-Cu spinel showed moderate porosity; Cu and Cu-rich spinel by far showed the highest porosity.

Centrifugal Concentration of Mandailing Natal North Sumatera Gold Ores Using Knelson Concentrator

Gravity concentration is the type of separation process of minerals based upon the difference in density. This technique has been known for centuries. It has the ability to separate the valuable minerals with relatively low production cost and little environmental impact, such as gold ores. Separation of gold from gangue minerals by using gravity concentration has been used for decades. In fact, it has the limitation to process fine particles. In attempt to recover fine particles using gravity concentration methods, the technique has been developed by combining centrifugal force. One of wellknown devices, Knelson Concentrator, was used to separate gravity recoverable golds (GRG) from the gangue minerals of Mandailing Natal (North Sumatera) sulfide complex gold ores with -200# of particle size. The head grade of ores was 5 g/t of gold. The ores were separated by using Knelson Concentrator with variation of pulp density, feeding rate, and water fluidization pressure. The results have proved that these three variables have particular impacts on gold recovery. The recovery of gold was increased by the increasing of pulp density until it reached the optimum level in 25% of solid with 86.9% of gold recovered, and then decresed by increasing of pulp density into 84.88% of gold with 30% of solid in pulp. It has the same trends in variation of feeding rate and water fluidization pressure. The highest point with 87.08% of recovery and 17.88 g/t of concentrate grade was anchieved at 25% of solid, 0.7 kg/minutes of feeding rate, and 2.7 kg/cm2 of water fluidization pressure.

Leaching/Bioleaching and Recovery of Metals

Hydrometallurgical processes for metal extraction are becoming more and more popular as average ore grades are declining and huge tonnages of tailings and recycle materials containing valuable metals are being accumulated all around the world [...]

Dynamic analysis of future nickel demand, supply, and associated materials, energy, water, and carbon emissions in China

Nickel demand is increasing globally and in China as a result of increasing demand for its traditional applications and the transition in energy and transportation sectors. Meanwhile, nickel production is associated with significant energy, water and carbon emissions, which are expected to increase due to increasing demand, decreasing ore grade, and production processes shift. In this paper, we analyse material-energy-water-climate nexus associated with nickel use in China using a dynamic material flow-stock model and several scenarios for nickel demand in traditional applications, energy supply technologies, and electric vehicles, and its supply from primary and secondary sources. The results indicate that nickel demand is expected to increase in all scenarios and stabilize between 2034 and 2040. Secondary supply could cover between 51 and 65% of the demand by 2050 if China is restricting scrap import, while up to 85% without restriction. Average annual energy associated with nickel production constitutes between 2.6 and 6.9% of total electricity consumption in China in 2018. Importing scrap reduce between 27 and 42% of cumulative energy. Average annual CO2 emissions constitute between 0.2 and 0.52% of the power sector emissions in 2018, and average annual water constitutes between 0.09 and 0.31% of total water consumption in industrial sector in 2015, mainly attributed to indirect water consumption.

Nickel Laterites—Mineralogical Monitoring for Grade Definition and Process Optimization

Nickel laterite ore is used to produce nickel metal, predominantly to manufacture stainless steel as well as nickel sulfate, a key ingredient in the batteries that drive electric vehicles. Nickel laterite production is on the rise and surpassing conventional sulfide deposits. The efficiency of mining and processing nickel laterites is defined by their mineralogical composition. Typical profiles of nickel laterites are divided into a saprolite and a laterite horizon. Nickel is mainly concentrated and hosted in a variety of secondary oxides, hydrous Mg silicates and clay minerals like smectite or lizardite in the saprolite horizon, whereas the laterite horizon can host cobalt that could be extracted as a side product. For this case study, 40 samples from both saprolite and laterite horizons were investigated using X-ray diffraction (XRD) in combination with statistical methods such as cluster analysis. Besides the identification of the different mineral phases, the quantitative composition of the samples was also determined with the Rietveld method. Data clustering of the samples was tested and allows a fast and easy separation of the different lithologies and ore grades. Mineralogy also plays a key role during further processing of nickel laterites to nickel metal. XRD was used to monitor the mineralogy of calcine, matte and slag. The value of mineralogical monitoring for grade definition, ore sorting, and processing is explained in the paper.

AI4R2R (AI for Rock to Revenue): A Review of the Applications of AI in Mineral Processing

In the last few years, jargon, such as machine learning (ML) and artificial intelligence (AI), have been ubiquitous in both popular science media as well as the academic literature. Many industries have tried the current suite of ML and AI algorithms with various degrees of success. Mineral processing, as an industry, is looking at AI for two reasons. First of all, as with other industries, it is pertinent to know if AI algorithms can be used to enhance productivity. The second reason is specific to the mining industry. Of late, the grade of ores is reducing, and the demand for ethical mining (with as little effect on ecology as possible) is increasing. Thus, mineral processing industries also want to explore the possible use of AI in solving these challenges. In this review paper, first, the challenges in mineral processing that can potentially be solved by AI are presented. Then, some of the most pertinent developments in the domain of ML and AI (applied in the domain of mineral processing) are discussed. Lastly, a top-level modus operandi is presented for a mineral processing industry that might want to explore the possibilities of using AI in its processes. Following are some of the new paradigms added by this review. This review presents a holistic view of the domain of mineral processing with an AI lens. It is also one of the first reviews in this domain to thoroughly discuss the use of AI in ethical, green, and sustainable mineral processing. The AI process proposed in this paper is a comprehensive one. To ensure the relevance to industry, the flow was made agile with the spiral system engineering flow. This is expected to drive rapid and agile investigation of the potential of applying ML and AI in different mineral processing industries.

Determination of Gold Particle Characteristics for Sampling Protocol Optimisation

Sampling, sample preparation, and assay protocols aim to achieve an acceptable estimation variance, as expressed by a relatively low nugget variance compared to the sill of the variogram. With gold ore, the typical heterogeneity and low grade generally indicate that a large sample size is required, and the effectiveness of the sampling protocol merits attention. While sampling protocols can be optimised using the Theory of Sampling, this requires determination of the liberation diameter (dℓAu) of gold, which is linked to the size of the gold particles present. In practice, the liberation diameter of gold is often represented by the most influential particle size fraction, which is the coarsest size. It is important to understand the occurrence of gold particle clustering and the proportion of coarse versus fine gold. This paper presents a case study from the former high-grade Crystal Hill mine, Australia. Visible gold-bearing laminated quartz vein (LV) ore was scanned using X-ray computed micro-tomography (XCT). Gold particle size and its distribution in the context of liberation diameter and clustering was investigated. A combined mineralogical and metallurgical test programme identified a liberation diameter value of 850 µm for run of mine (ROM) ore. XCT data were integrated with field observations to define gold particle clusters, which ranged from 3–5 mm equivalent spherical diameter in ROM ore to >10 mm for very high-grade ore. For ROM ore with clusters of gold particles, a representative sample mass is estimated to be 45 kg. For very-high grade ore, this rises to 500 kg or more. An optimised grade control sampling protocol is recommended based on 11 kg panel samples taken proportionally across 0.7 m of LV, which provides 44 kg across four mine faces. An assay protocol using the PhotonAssay technique is recommended.

The use of solar energy in the copper mining processes: A comprehensive review

The copper mineral processing industry faces complex scenarios with increased demand, highly variable energy prices, falling ore grades that increase energy consumption, and increasing concern about the industry's carbon footprint. To reduce the risk imposed by these scenarios, the industry is looking at the use of renewable energy sources. Considering that the most important copper mines in Chile are situated in regions with high radiation levels, solar energy has the potential to be an attractive and sustainable source of energy. This paper provides an overview of the current solar technologies and how they have been applied to address some of the challenges faced by the copper mining industry today. It describes the use of solar thermal and solar photovoltaic technologies to produce power and heat for the copper mining processes. Indeed, solar photovoltaic technologies can be used to produce electricity for the comminution machines, electro-refineries and water pumping while solar thermal technologies are useful for electricity generation, heat production, thermal leaching and drying of copper concentrate. The review also analyzes, from a broader perspective, the potential of these technologies in the operation and design of new solar copper mineral processes. It is concluded that there several feasible options to integrate solar energy into the copper mining processes.

Kajian Perolehan Hasil Bijih Timah Berdasarkan Ukuran Butir Terhadap Variabel Magnetic Separator Skala Laboratorium

Industrial-scale Magnetic Separator is used to process tin ore by separating magnetic and nonmagnetic minerals using a belt conveyor speed and splitter opening only one variation. Based on this, this research is intended to obtain a more varied and optimal combination of variable settings in the recovery of tin ore yields. The method used is quantitative data analysis method by obtaining nonmagnetic minerals using a combination of splitter openings and belt conveyor speed based on grain size, calculating the content of tin ore in non-magnetic minerals using the Grain Counting Analysis method and calculating the composition of tin ore recovery. The research was conducted based on grain sizes of 60 mesh, 80 mesh, and 120 mesh using a combination of splitter opening sizes of 0.2 cm, 0.4 cm, and 0.6 cm and using a belt conveyor speed of 27.12 cm/s, 28.15 cm/s, and 28.40 cm/s. The sample used for each grain size is 9,000 grams with repetition for each combination of variables, namely 30 times. The results of this study obtained the highest yield of tin ore at grain size of 80 mesh as much as 1,753.7 grams in 8,920.3 grams of non-magnetic minerals with tin ore grades of 19.66% using a combination of speed 27.12 cm/s and splitter opening 0.2 cm. Based on the results of the study, the tin ore contained in the non-magnetic material processed by the Magnetic Separator, the grain size of 80 mesh is higher than that contained in the grain size of 60 mesh, while the grain size is finer than 80 mesh, the lower the recovery of tin ore contained in the non-magnetic material. Meanwhile, the larger the splitter opening and the speed of the conveyor belt, the higher the nonmagnetic minerals obtained.

Genesis of langrial iron ore of hazara area, khyber pakhtunkhaw, parkistan

The Iron Ore of Hazara area has been studied at seven locations for detail mineralogical and genesis investigations. Thick bedded iron ore have been observed between Kawagarh Formation and Hangu Formation i.e Cretaceous-Paleocene boundary. At the base of Hangu Formation variable thickness of these lateritic beds spread throughout the Hazara and Kohat-Potwar plateau. This hematite ore exists in the form of unconformity. X-Ray Diffraction technique (XRD), X-ray Fluorescence Spectrometry (XRF), detailed petroghraphic study and Scanning Electron Microscope (SEM) techniques indicated that iron bearing minerals are hematite, chamosite and quartz, albite, clinochlore, illite-montmorillonite, kaolinite, calcite, dolomite and ankerite are the impurities present in these beds. The X-ray Fluorescence (XRF) results show that the total Fe2O3 ranges from 39 to 56% and it has high silica and alumina ratio is less than one. Beneficiation requires for significant increase in ore grade. The petroghraphic study revealed the presence of ooids fragments as nuclei of other ooids with limited clastic supply which indicate high energy shallow marine depositional setting under warm and humid climate. The overall results show that Langrial Iron ore is a low-grade iron ore and can be upgraded up to 62% by applying modern mining techniques to fulfill steel requirements of the country.