Mineral Processing Operations Research Articles

Modeling and Simulation of Hydroxyapatite Recovery in the Desliming Circuit of the Tapira Industrial Plant, Brazil

The modeling and simulation of industrial mineral processing operations are traditionally used for cyclone sizing and optimizations of industrial operations. However, the main models used are based on the total population of particles in the pulp, thus not distinguishing the individual minerals. This article presents the results of an innovative method that investigated the optimization of the metallurgical recovery of P2O5 in the desliming circuit of a phosphate ore processing plant in Brazil. A survey campaign was carried out in the existing industrial circuit, followed by determining the partition curves for the overall particles and specifically for the hydroxyapatite particles. The results were used to calibrate the Narasimha–Mainza cyclone model. From a Base Case determined with reference to the industrial survey, three optimization scenarios were simulated through cyclone geometries and respective operating conditions changes. Simulated scenarios indicated the possibility of P2O5 metallurgical recovery increasing from 9.4% to 12.7% compared to the Base Case.

Fire and Water: Geometallurgy and Extractive Metallurgy

There is no doubt that mineralogy, texture, and microfabric, as primary characteristics of an ore, affect mineral processing operations. Their direct effects on extractive metallurgical processes and the associated optimization potential, however, are less well documented. Here, we examine the status of geometallurgical approaches in extractive metallurgy by focusing on the effects of primary ore characteristics in hydrometallurgical and pyrometallurgical processes. Two selected case studies illustrate the linkages. Using quantitative data analytics on ores and concentrates, the possibilities for optimized and sustainable metal extraction and waste valorization are discussed.

Baseline assessment of naturally occurring radionuclides in borehole water of Asikam-gold mining community in Ghana

The main source of drinking water and domestic usage for the population of Asikam in the Fanteakwa South Municipality is from hand-dug wells and mechanized boreholes. This study assessed naturally occurring radionuclides Radium-226(Ra-226), Thorium-232(Th-232) and Patassium-40(K-40) in the water from these sources. A random sample of 20 sampling points made up of 7 manually dug wells and 13 mechanically drilled boreholes were taken from Asikam Communities. The radioactive contents of the selected water sources were characterized and analysed using gamma spectrometry system with High Pure Germanium Detector. This assessment was carried out to determine the level of natural radioactivity that the processing of gold ore at the Asikam illegal mining site in Ghana exposes the public to. The mean activity concentrations of Ra-226, Th-232, and K-40 were obtained as 0.30 Bq/L, 0.49 Bq/L, and 2.44 Bq/L in the water samples respectively. The results from this study were found to be lower than the Guidance levels recommended by the World Health Organization (WHO, 2011; IAEA,2014) of 1 Bq/l for Ra-226 and Th-232. The estimated average committed annual effective dose for water samples was 0.17 mSv/yr which is lower than the 1 mSv/yr recommended limits for public exposure by the WHO. The cancer fatality risk and hereditary consequences from exposure to naturally occurring radionuclides which may result from the Asikam community's mining and mineral processing operations were evaluated and found to be insignificant. The findings of this study demonstrate radioactivity levels are within the range of natural background radiation levels as reported in the literature, and they compare favorably with findings from comparable studies conducted nationally and internationally. This study provides important baseline information for future research in the study area.

Environmental impacts and improvement potentials for copper mining and mineral processing operations in China

There has been growing concern among the public over the environmental impacts of the copper (Cu) mining and mineral processing industries. As an effective tool enabling interactions of all energy and material flows with the environment, Life Cycle Assessment (LCA) is used in many countries to identify environmental hotspots associated with operations, based on which improvements can be made. However, robust LCA research in this sector is lacking in China. This study aimed to fill this critical gap by investigating two typical Cu mining and mineral processing operations using different mining technologies, based on globally harmonized LCA methodologies. The results of the overall environmental impacts were obtained using a sensitivity analysis. Electricity (38%–74%), diesel (8%–24%) and explosives (4%–22%) were identified as the three main controlling factors. At the same time, the mineral processing stage was found to be the major production stage (60%–79%), followed by the mining stage (17%–39%) and the wastewater treatment (1%–13%). Global Warming Potential (GWP) was prioritized as the most important environmental issue (59%) across the selected impact categories. In addition, it was initially found that underground mining technology has better environmental performance than open-pit technology. Finally, the potential for improvement was estimated and discussed for the three identified controlling factors. Using GWP as an example, using green electricity can effectively reduce CO2 emissions by 47%–67%, whereas replacing diesel and explosives with cleaner fuels and explosives may contribute to lower CO2 emissions by 6% and 9%, respectively.

102 Application of Quantitative Mineralogy to Determine Sources of Airborne Particles at a European Copper Smelter

Abstract To ensure that regulatory compliance is maintained at mineral processing operations, worker exposure is regularly monitored. Determining the quantity and type of airborne particles permits the operation to identify the sources of dust, implement proper dust suppressant strategies, and ultimately, limit worker exposure. Conventional methods of analysis, such as chemical assay, are unable to rigorously differentiate between phases containing the same elements and may result in ambiguity related to identifying the source of airborne dust. A combination of Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) and chemical characterization has been used to evaluate personally taken size selective aerosol samples at key locations throughout a Cu smelter in Europe. Surface samples were also examined using higher resolution measurements. The Cu phases present in the workplace air samples are reflective of the activities performed at specific locations. Near the anode and electric furnace, the majority of Cu in the airborne dust is carried in metals and oxide phases (60-70%), and in the batch preparation area where Cu concentrate is received, significant amounts of Cu are carried in sulfide minerals (chalcocite, chalcopyrite/bornite, >40%). The results of the analysis will aid in the identification of the origin of emissions specific to location and activity, assist personnel in developing the appropriate mitigation strategies to limit workers exposure, and further understanding of the health risks associated with exposure. Additional metals of concern (e.g, Pb, As, and Cd) are also considered throughout this program. Speaker Biography Michelle Kelvin is a geoscientist and environmental mineralogist. She specializes in characterizing dust emissions that originate from industrial operations using modern geochemical methods and X-ray beam technologies.

Reliability analysis of the compressed air supplying system in underground mines

Despite the high cost and low efficiency, compressed air is mostly used in underground mining for ore extraction, hoisting, and mineral processing operations. Failures of compressed air systems not only threaten the health and safety of workers but also contribute to inefficient control of airflow and stopped all equipment that operates by compressed air. In such uncertain conditions, mine managers are faced with the big challenge to supply enough compressed air, and therefore, the reliability evaluation of these systems is essential. This paper aims to analyze the reliability of the compressed air system using the Markov modeling approach as a case study, Qaleh-Zari Copper Mine, Iran. To achieve this, the state space diagram was constructed considering all relevant states for all compressors in the main compressor house of the mine. The failure and repair rate of all main and reserve compressors were calculated for all possible transitions between states to obtain the probability of being of the system in each of the states. Moreover, the probability of failure at any time period was considered to study the reliability behavior. The results of this study show that there is 31.5% probability that the compressed air supplying system is in operating condition with two main and one standby compressors. The system probability that two main compressors are remain in the operation without failure for one months is 92.32%. Furthermore, the lifetime of the system is estimated 33 months when at least one main compressor is active.

Nanofiltration for treatment of Western Australian bore water for mineral processing operations: A pilot scale study

Limited freshwater availability, increasing competition for water among multiple users, cost of purification, corporate sustainability goals, etc., are the main factors driving many industries to focus on water quality and usage. Increasing water reuse and accessing alternative sources of freshwater are potential strategies to improve water efficiency. This paper aims to identify water treatment options that produce suitable water for flotation and other mineral processing operations. It investigates the performance of nanofiltration membranes in producing suitable water quality for the separation of minerals based on the ionic strength tolerance threshold at which impurities begin to impact the separation process. In this study, the membranes used could reject >95 % of divalent cations (such as Ca2+ and Mg2+) and >74 % of monovalent ions (e.g., Na+ and Cl−) under the conditions of 12 bar of transmembrane pressure and 65 % of the recovery. These rejection rates were found to be sufficient to produce fit-for-purpose water for mineral processing. In addition, the effect of pressure on the mass transfer mechanism of each membrane was determined.

Circular Economy Models in Industry: Developing a Conceptual Framework

One of the trends in sustainable economic development is the transition to circular business models, which aim to optimize goods and material flows by taking into account their cyclical nature at all production stages. Adapting circular business models to mining and mineral processing operations can serve as an impetus for mining companies to upgrade and move to a new level of technological sophistication. This article attempts to develop a conceptual framework for circular business models factoring in the nature of production chains in coal mining, power generation, and metal production to reduce production costs, expand the product range, improve sustainable development indicators, and deliver growth in company value. This article is based on desk studies that were aimed at analyzing the efficiency of circular models, organizing data on experience in rational resource use in the mining industry, and transforming basic circular models into adapted ones for the environment in which coal companies operate. This study developed a conceptual framework of options for the implementation and evaluation of circular business models using an interdisciplinary approach and taking into account the specific features of coal companies and the principle of a resource being valuable throughout its whole life cycle. The proposed conceptual framework of circular business models can be used by Russian coal companies to design corporate strategies and long-term development plans.

Molecular Dynamics Simulations of the Interactions between a Hydrolyzed Polyacrylamide with the Face and Edge Surfaces of Molybdenite.

Process water used in mineral processing operations corresponds to water recovered from the thickeners and tailings dams, containing residual reagents such as hydrolyzed polyacrylamides (HPAMs). These polymers depress the flotation of different minerals, and their effect on molybdenite has been experimentally demonstrated. The objective of this work was to study the interactions between a segment of a HPAM with the face and edge of molybdenite. The sigma profile, the radial distribution functions of the HPAM, and the orientation and atomic density profiles of water molecules on the face and edge surfaces of molybdenite were calculated. The results obtained from molecular dynamics simulations showed that the interactions between the HPAM and molybdenite are mainly explained by the interactions of the amide group with the faces and edges of the mineral. Molecular dynamics simulations also showed that the HPAM molecule rearranges in such a way that the amide group moves towards the molybdenite face or edge, and the carboxylate group moves away from the mineral surface. The results obtained in the simulations showed that the interactions of the HPAM with the molybdenite edge are slightly stronger than the interaction of this molecule with the mineral face. Simulations demonstrated that the presence of the sodium and hydroxide ions reduces the concentration of HPAM around the face and edge surfaces, which is expected to affect HPAM adsorption on molybdenite. The conclusions obtained through molecular dynamics simulations are in line with the results obtained in previous studies carried out at a macroscopic scale, which reported that HPAMs adsorb onto molybdenite particles and reduce their hydrophobicity.

An efficient method for computational flow-based simulation of heat transfer in a rotary kiln with pilot scale validation

• Counter-current rotary kiln 5.27 m long, operated with two different feeds of gravel. • Temperature measurements taken along the kiln under various operating conditions. • Novel fast efficient computational model developed to predict bed temperature. • Predicted temperature profile in reasonable agreement with the measurements. • Model allows rapid, but reliable assessment of kiln design and operating conditions. Rotary kilns are used to carry out heating and chemical transformation in several mineral processing operations. A series of experimental runs was carried out using the realistic but controlled arrangement of a pilot rotary kiln to obtain temperature data for the validation of a novel model that couples a computational fluid dynamics model of the flame to a granular bed model through heat transfer terms. The rotary kiln was 5.27 m long, with an internal diameter of 410 mm, and two different feeds of inert standard commercial gravel were used in the runs, with the kiln operating in counter-current operation. Each of the feeds was run through the kiln under various operating conditions (feed rate, kiln rotation speed, fuel rate and weir height), and kiln temperature profiles were measured during each run. The effect of various operating parameters on heat transfer within the kiln was then determined. A fast and efficient computational model of the pilot kiln was developed to predict the burner flame and heat transfer in the kiln; the granular bed was modelled using a one-dimensional model which was coupled in a pragmatic way to the computational fluid dynamics gas phase model. Dependence of the predicted temperature profile on operating parameters is in reasonable agreement with the measurements, and the model can be run rapidly for efficient assessment of a large number of design and operating condition options. While there have been an increasing number of papers published in recent years reporting very detailed models of the motion in granular beds in rotary drums that are extremely valuable for a fundamental understanding of issues such as segregation, such models are very computationally intensive, and are still not feasible for industrial-scale kilns in which the particles are small. This paper indicates that good predictions of process parameters such as bed temperature are possible without such very time-consuming computations. Moreover, the experimental temperature measurements will be useful for future rotary kiln studies.

Process simulation to determine blending and residence time distribution in mineral processing plants

Mineral processing plant performance depends on multiple factors, including the feed and the parameters to control the process. In this work, we show how to assess plant performance using geometallurgical modeling and dynamic simulation. Several models that describe comminution, classification, flotation, and residence time distribution (RTD) are implemented as modules and then connected to represent generic plant configurations. The estimation of the RTD is used to assess the ore blending generated within the plant through a methodology based on weighting the ore contribution at the plant discharge. Additionally, the RTD is used to display the ore permanence at different plant stages, which can be used as an operational input to anticipate the consequences of a perturbation in the feed. Different simulation scenarios are tested using synthetic data, including different plant configurations, time support for blending assessment, and ore feeding sequence. The results show that the simulation is sensitive to these attributes. Significant differences are detected in the generated product compositions when the plant configuration is changed. Also, distinct mine plans can be evaluated through simulation, predicting their processing performance. Therefore, the simulation tool developed can be used to evaluate real mineral processing operations and to test different operative strategies.

A review of the influence of blast fragmentation on downstream processing of metal ores

Rock fragmentation is one of the most commonly optimized blasting outcomes due to its significant influence on the efficiency of downstream operations. This paper reviews the influence of blast fragmentation on processing of metal ores. Two aspects of rock fragmentation that influence downstream mineral processing operations include the particle size of the run-of-mine ore and the degree of internal microfracturing in the fragments induced by blasting. The main influences identified include productivity of comminution equipment, energy consumption in comminution equipment and mineral recovery. An increase in blasting energy results in higher throughput and energy reduction in comminution circuits. Increase in blasting energy results in energy savings in the overall mining operations. However, when increasing the blasting energy, the environmental and safety impacts must be taken into consideration. Blast-induced microfractures increase the permeability of the fragments, therefore enhancing mineral exposure to leaching reagents and consequently may lead to higher mineral recoveries, particularly in heap and dump leaching operations which employ-one-stage comminution. However, the textural characteristics of the ore also influence the mineral recovery. Further research should focus on establishing the relationship between blast intensity and mineral leaching recovery for metal ores of different textural properties.

Characterization of Particulate Matter Generated at a Nickel Smelter Using Quantitative Mineralogy

Activities performed at mineral processing operations are capable of producing significant quantities of dust. To ensure that regulatory compliance is maintained throughout operation, dust levels are monitored by routine analysis of air filter samples. Determining the quantity and type of particulate matter present in dust allows for the operation to identify the sources of dust and where warranted, implement a dust suppressant strategy. Conventional methods of analysis, such as chemical assay, are unable to rigorously differentiate between phases containing the same elements and may result in ambiguity related to the identification of dust sources. By incorporating Quantitative Evaluation of Materials by Scanning Electron Microscope (QEMSCAN) into their routine monitoring programs, the Sudbury INO smelter has greatly improved characterization of the Ni and Co dust emissions generated at the operation. To determine specific activities responsible for emissions, bulk particulate matter was sampled from several key locations at the smelter that regularly produce dust. QEMSCAN was able to distinguish between critical subspecies of Ni and Co and mineralogical, and chemical signatures in the dust that are representative of locational activity were established. An apportionment of elements contributed by each source was calculated based on this information. The results of the characterization study assisted personnel in developing strategies to mitigate dust emissions that originate from the Smelter operations, and have general implications to occupational hygiene and environmental risk assessment.

Decarbonization of mineral processing operations: Realizing the potential of carbon capture and utilization in the processing of ultramafic nickel ores

Mining and mineral processing operations are responsible for 4 to 7 percent of greenhouse-gas emissions globally and are under a huge pressure to reduce their emissions. Decarbonization through CO2 capture and utilization is a lucrative option only when the captured CO2 can be utilized to bring down the costs such as in oil recovery from reservoirs where the injected CO2 increases the recovery. Unfortunately, in mining operations, the captured CO2 doesn’t have any utilization so far which is a primary reason of mining industry’s sluggish response for decarbonization commitments. Herein, we provide a first proof of CO2 capture and utilization in nickel mineral processing industry by using CO2 as a conditioning agent prior to froth flotation resulting in the conversion of monohydroxide complexes to carbonates which increases electrostatic repulsion between the valuable mineral and the gangue leading to enhanced froth flotation recovery. The inclusion of CO2 to the froth flotation improved the nickel recovery and grade by an extra 10% and 4%, respectively while permanently storing the CO2 at the same time. The study provides a strong motivation for decarbonatization in the industry through CO2 utilization.

Geochemical modelling of diethylenetriamine in tailings management areas

Diethylenetriamine (DETA) is an effective mineral processing reagent for the depression of pyrrhotite in the flotation of Cu-Ni ores. DETA is a chelating agent and forms stable complexes with Cu and Ni ions that cannot be removed with traditional mining effluent treatment. The recalcitrance of metal-DETA complexes to wastewater treatment can result in effluent quality that does not meet regulatory requirements. To better understand the behaviour of DETA in the tailings and effluent environments, the interaction of DETA with metal species was investigated via geochemical modelling using OLI Studio. The concentrations and specific species of metal-DETA complexes were modelled with varying pH levels and metal-to-DETA ratios. The results suggest that DETA is most likely to chelate with Cu2+, followed by Ni2+. Very little Fe2+ is expected to combine with DETA, especially when Ni2+ and Cu2+ are present. Moreover, both Cu-DETA and Ni-DETA chelates are stable over the pH range of 4 to 14. The modelling results agree with what has been observed in mineral processing operations. Sulphide precipitation was also investigated as a possible treatment technique and appears promising for the removal of Cu2+ and Ni2+ from DETA-containing effluent.

Application of Multivariable Data Analysis in Mineral Processing

Data analysis and application of machine learning (ML) have demonstrated successful performance in various data rich industrial applications. Mineral processing and metallurgical operations are considered suitable for implementation of novel ML-based algorithms. The key operating performance and product outputs are usually obtained from the lab measurements and analyses that can be expensive, complex, and time consuming. Therefore, the development and application of a soft sensor and/or a state observer is a useful option to be considered due to their ability to provide the distribution of desired outputs in a continuous manner. In addition, the motivation to apply a soft sensor (a data-based model) is to provide guidance and/or information feedback to the operator in charge of making operational decisions. The soft sensor was developed at Sherritt's Metal Plant in Fort Saskatchewan as a nonlinear neural network model and it was based on two years of plant historical data. The model was also validated based on historical data, live testing, and additional sampling of process streams during simultaneous sampling campaign.

Recent Advancements in Metallurgical Processing of Marine Minerals

Polymetallic manganese nodules (PMN), cobalt-rich manganese crusts (CRC) and seafloor massive sulfides (SMS) have been identified as important resources of economically valuable metals and critical raw materials. The currently proposed mineral processing operations are based on metallurgical approaches applied for land resources. Thus far, significant endeavors have been carried out to describe the extraction of metals from PMN; however, to the best of the authors’ knowledge, it lacks a thorough review on recent developments in processing of CRC and SMS. This paper begins with an overview of each marine mineral. It is followed by a systematic review of common methods used for extraction of metals from marine mineral deposits. In this review, we update the information published so far in peer-reviewed and technical literature, and briefly provide the future perspectives for processing of marine mineral deposits.

Effects of niobium macro-additions to high chromium white cast iron on microstructure, hardness and abrasive wear behaviour

Abrasive wear is a principal cost in mining and mineral processing operations. High chromium white cast iron (WCI) further reinforced with niobium carbide (NbC) shows promise to increase component wear lives. This work investigates the effect of niobium macro-additions on microstructure, hardness and high-stress abrasive wear behaviour of Nb-containing high-Cr WCIs. Eight alloys with Nb between 0 and 10.7 wt% were produced by sand casting. Increasing niobium carbide volume fraction (Nb-CVF) increased hardness from 724 to 812 HV (7.3 HV per 1% Nb-CVF). Abrasive wear resistance, assessed using the ball mill abrasion test in basalt (less competent) and quartzite (competent rock), showed clear beneficial effect of NbC macro-addition up to 11.4 and 7 vol% in basalt and quartzite, respectively. These correspond to life improvements of 37% and 7% per 1% Nb-CVF in the optimum range of Nb macro-addition, in basalt and quartzite respectively. Micro-mechanistic observations of worn surfaces showed that NbC particles not only protrude from the matrix but do so more than Cr-rich M7C3 carbides. In deep wear grooves created by quartzite, M7C3 particles were cut flush with the matrix, whereas NbC protruded, visibly impeding the progress of the abrasion event.

Gold and silver deportment in sulfide ores – A case study of the Freiberg epithermal Ag-Pb-Zn district, Germany

Deportment data is essential for the planning of mining and minerals processing operations. This need is particularly tangible for deposits of noble metals, such as gold and silver. Therefore, the current paucity of published gold and silver deportment data for individual ore deposits and districts – and the concomitant lack of understanding how this relates to salient geological and mineralogical features of these deposits – is surprising. In the present study, we apply a combination of bulk geochemistry, laser ablation-inductively coupled plasma-mass spectrometry, electron microprobe analysis, and mineral liberation analysis to gold- and silver-rich samples from the epithermal Freiberg Ag-Pb-Zn district, to investigate variability in gold and silver deportments, as well as the corresponding geological/mineralogical controls. The results show that the main carriers of gold are electrum and arsenopyrite, whereas silver is mostly hosted by Ag-sulfosalts (pyrargyrite, miargyrite, polybasite) and fahlore (freibergite). Deportments vary greatly between samples. These variations can be related to the relative abundances of different minerals within the samples, which in turn reflect their spatio-temporal position within the district. Comparisons with other epithermal Ag-Pb-Zn districts similar to Freiberg indicate that the results presented here are of general significance.

Biowaste-based biodegradable flocculants for clean and sustainable tailings management in industrial mining and mineral processing

Massive fluid tailings discharged from industrial mining and mineral processing operations pose numerous economic and environmental challenges. To remove water and condense tailings into sediment, we developed a novel bioflocculant from specified risk materials, a particular type of waste biomass from the animal rendering industry. By properly controlling key synthesis conditions, the bioflocculant successfully met industrial requirements for fluid tailings treatment, including enhanced short-term tailings settling and improved ultimate water removal extent. Settling tests using real industrial fluid tailings showed that the synthesized bioflocculant enabled an initial settling rate 4 magnitudes higher than the control case and achieved 93.2% the dewatering efficiency of a commercial flocculant (hydrolyzed polyacrylamide; HPAM). In contrast to HPAM, our bioflocculant can achieve tailings settling without gypsum, a common processing aid that can hinder downstream industrial operations. More importantly, growth tests using two common microorganisms (Saccharomyces cerevisiae and Escherichia coli) suggested that the bioflocculant can be easily degraded, indicating reduced negative environmental impacts after its use. Taken together, this study demonstrates the great potential of implementing a biodegradable bioflocculant from proteinaceous wastes for clean and sustainable management of mining and mineral processing fluid tailings.