Blogs

Seven new Mining, Metallurgy & Exploration (MME) journal papers have just been published on Springer's Online First. 

To get your free download of these papers: (1) Go to www.smenet.org/login. Sign in with your email address and password. (2) Hover your mouse over "Publications and Resources" in the top banner. Click on "Mining, Metallurgy & Exploration (MME) Journal" in the pull-down menu. (3) Scroll down and click on the "Read the MME Journal Online" button. To see published issues, click on "Browse Volumes & Issues" in the blue banner.

Heap Leach Production Modeling: a Spreadsheet-Based Technique
by Mike Botz and John Marsden
Cite this article as:
Botz, M. & Marsden, J. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00129-0

Abstract
A variety of modeling techniques can be utilized to forecast metal production at heap leaching operations. These approaches reflect a wide range of complexity, flexibility, time to implement, cost, and accuracy. For many operators, a spreadsheet-based modeling technique is attractive since the calculations are directly accessible, models can often be developed by site staff, and the results are generally easy to extract and interpret. The authors have developed a spreadsheet-based modeling technique that provides a high degree of flexibility, while still considering detailed operating information for ore properties, leach kinetics, scale-up factors, lift height, and in-heap metal inventories. The technique involves establishing kinetic leach curves for each ore type to characterize metal extractions, followed by application of separate metal recovery curves to define the rate at which leached metals exit the heap in pregnant solution, taking into account delays due to the in-heap solution inventory. At any point in time, the difference between total metal extracted and total metal recovered is equal to the in-heap inventory of the leached metal. This modeling technique is particularly useful for larger multi-lift heaps where delays in metal recovery are appreciable due to in-heap solution holdup. The technique is also applicable to sites with multiple heaps, leach cycles, and/or metal recovery plants (e.g., carbon columns for gold; solvent extraction for copper). This paper describes the modeling technique, including input data required and methods for defining kinetic leach curves and metal recovery curves. The technique is compared against an alternative spreadsheet technique using a simplified in-heap solution inventory calculation to forecast metal production, which has proven to be effective at a number of sites.

A Field Survey of Rare Earth Element Concentrations in Process Streams Produced by Coal Preparation Plants in the Eastern USA
by Gerald H. Luttrell, Michael J. Kiser, Roe-Hoan Yoon, Aaron Noble, Mohammad Rezaee, Abhijit Bhagavatula, Rick Q. Honaker
Cite this article as:
Luttrell, G.H., Kiser, M.J., Yoon, RH. et al. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00124-5

Abstract
A field study was undertaken to experimentally measure the concentrations of rare earth elements (REEs) contained in the process streams generated by a group of 20 coal preparation plants located in the eastern USA. For each site, representative samples of clean coal product, coarse refuse, and fine refuse were collected. Each sample was then partitioned into preselected size and density classes by wet screening/sieving and float-sink testing. The resultant products were dried and subjected to laboratory analyses to determine ash contents and rare earth element concentrations including Yttrium and Scandium. A detailed analysis of the database generated by this exercise showed that coal-based products from these preparation plants contained significant quantities of rare earth elements. In particular, the coarse refuse streams currently discarded by the 20 plants examined were found to contain a sufficient tonnage of REEs to satisfy the current domestic demand for these important elements. The data also showed a strong positive correlation between ash content and REE concentration, which suggested that the primary association of REEs in eastern USA bituminous coal sources is likely within fractions containing inorganic impurities. This association was well described using a simple power equation relating ash content and REE concentration. The ratio of heavy-to-light rare earth elements was discovered to be significantly higher in organically rich fractions of clean coal, suggesting that mineral impurities intimately associated with carbonaceous matter have elevated concentrations of heavy rare earth elements. A similar trend was observed for a grouping of rare earth elements (Y, Nd, Eu, Tb, and Dy) that are likely subject to near-term supply shortages. Finally, the database showed that a linear correlation existed between La for many REEs of interest, although there were several notable exceptions for some high-value REEs (Lu, Pr, and Tb).

Experimental and Numerical Investigations of the Fluid Flow in a Hydroclyclone with an Air Core
by Renjie Ke, Chinmay Shingote, Jaikrishnan R. Kadambi, John Furlan, Robert Visintainer
Cite this article as:
Ke, R., Shingote, C., Kadambi, J.R. et al. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00131-6

Abstract
Hydrocyclone separators are widely used in various industrial applications in the oil and mining industries to sort, classify, and separate solid particles or liquid droplets within liquid suspensions, which are considered to be multiphase systems. Numerous valuable studies have been conducted in recent years to investigate the flow fields inside hydrocyclones. However, much of the information regarding the performance of cyclones in the literature has limitations and much of it cannot be considered as completely applicable to most real-world applications; many of the studies investigated the flow fields within extremely simplified hydraulic designs that are not representative of the complex geometries or large sizes which are typical in industry. Therefore, in this study, the two-phase flow system inside the actual hydraulic geometry of a milling circuit hydrocyclone is explored with the aid of both computational and experimental techniques (particle image velocimetry (PIV)). More specifically, the flow field with an air core has been investigated. In addition, the air-liquid two phases flow in a hydrocyclone might cause some challenges on both the computational and experimental sides. Two turbulence models are utilized in the numerical calculations: the Reynolds stress model and large eddy simulation. The computational studies are mainly focused on the local flow behavior and the prediction of the dimensions and shape of the air core. Different section planes of hydrocyclone are selected as planes of interest and divided into several fields of view (FOV) for PIV measurements. Two-dimensional experimental velocity vector maps are obtained in each of the fields of view. The computational results are validated globally using pressure and flow rate readings at the boundaries and locally by comparison to the PIV velocity vector maps and profiles.

Contribution to the Examination of the Mechanisms of Copper Loss with the Slag in the Process of Sulfide Concentrates Smelting
by Zivan Zivkovic, Predrag Djordjevic, Natasa Mitevska
Cite this article as:
Zivkovic, Z., Djordjevic, P. & Mitevska, N. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00125-4

Abstract
This paper presents the results of an experimental investigation into the distribution of copper in the slag of an industrial reverberatory furnace sulfide concentrates smelting process in the copper smelter RTB Bor (Serbia). The influence of copper content in the matte, the temperature and the height of the slag on the content of copper in the slag was determined as Cuoxide, Cusulfide and Cutotal and was based on possible mechanisms for the loss of copper in a silicate slag from the smelting of sulfide copper concentrates. The greatest quantity of copper in the silicate slag was found in the form of matte particles, which were captured in the slag as a result of the "flotation" of SO2 gas which was formed by magnetite reduction with FeS at the slag–matte interphase boundary.

Effect of Base Types on the Properties of MgO Particles Obtained from Dolomite Ore
by Mahmut Altiner
Cite this article as:
Altiner, M. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00122-7

Abstract
This study aimed to produce magnesium oxide (MgO) particles with different properties from dolomite ore using an experimental procedure comprising four stages: sample preparation (S1), HCl leaching (S2), precipitation (S3), and calcination (S4). Three different base sources (NaOH, KOH, and NH₄OH) were used as precipitant in the third stage to obtain magnesium hydroxide [Mg(OH)₂] from a leachate solution, which was obtained in the second stage. Next, Mg(OH)₂ particles generated by different alkali sources were calcined at various temperatures from 600–1000 °C for different durations (1–5 h). The effect of these base types on the properties of each product was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), atomic force microscopy (AFM), and wet chemical analyses. The experimental results indicated that each product was identified as periclase (MgO) mineral, which was produced with a specific surface area (SSA) of 4.49–44.54 m²/g depending on the production conditions. The surface roughness of the MgO particles increased with increasing calcination temperature. SEM analyses showed that MgO particles produced at a temperature of 600 or 800 °C were amorphous, indicating that the process was not influenced by the base type, but MgO crystals were smooth when the calcination temperature was 1000 °C. Finally, it was determined from all experimental findings that MgO particles produced via the addition of NaOH have superior properties (such as higher SSA and lower surface roughness) compared with MgO particles produced with KOH or NH₄OH as the alkali source. These properties led to great improvement of its usability in industry.

Upgrading of Phosphate Fines by Fatty Acid Flotation Using Amylase Enzyme as a Surface Modifier
by A. Yehia, K. E. Yassin, M. Amar
Cite this article as:
Yehia, A., Yassin, K.E. & Amar, M. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00126-3

Abstract
Phosphate fines (size ≤ 45 μm), from the Red Sea Region, Egypt, were subjected to beneficiation process to recover the phosphorite grains from such fines. The sample is characterized by low P2O5 content (18.78%) associated with gangue minerals such as silica (22.77% SiO2) and carbonate (2.01% MgO) indicating its low grade. Phosphate pre-concentrate was prepared by gravity separation, using Falcon, where 63.37% of the phosphate, with 24.94% P2O5, 1.46% MgO, and 10.54% SiO2, was firstly recovered reducing the mass flow to the subsequent beneficiation process. However, the gravity tailing was the feed for the reverse phosphate flotation using bench scale column flotation where oleic acid was used as a carbonate gangue collector and amylase enzyme as a phosphate depressant. Under the appropriate flotation conditions (0.1% amylase, 5·10−4 mol/dm3 oleic acid, and temp. 30 °C), phospho-concentrate assaying 0.61% MgO, 13.14% SiO2, and 27.85% P2O5 with a P2O5 recovery of 55.45%, was finally obtained without the use of expensive depressants, e.g., phosphoric acid or sodium silicate. A tentative flow sheet for the whole process was postulated.

Shielding Material Comparison for Electromagnetic Interference Mitigation for the Air Pump Motor of Personal Dust Monitors
by Jingcheng Li, Jacob Carr, Cory DeGennaro, Bruce Whisner, Patrick McElhinney
Cite this article as:
Li, J., Carr, J., DeGennaro, C. et al. Mining, Metallurgy & Exploration (2019). doi.org/10.1007/s42461-019-00123-6

Abstract
Since 2016, electromagnetic interference (EMI) of personal dust monitors (PDMs) with magnetic proximity detection systems (PDSs) has been observed in underground coal mines. The EMI causes the magnetic field measurements of a PDS to change, which, in turn, alters the calculated location of the miner relative to the machine. Any altered location calculation can potentially cause the PDS to fail to warn a worker who is at an unsafe distance from the machine, arousing a serious concern on safety hazard caused by EMI in underground mines. The search for EMI mitigation strategies led to the development and use of large shielding pouches and boxes to hold the entire PDM to reduce its magnetic emission. Research on these pouches and boxes found that although they were able to reduce the emitted radiation from the PDM, they also disturbed the magnetic field of the PDS, affecting its performance. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have focused on shielding internal PDM components rather than shielding the entire PDM. The PDM air pump motor is one of the PDM components that has been identified as a major source of electromagnetic radiation and has been selected for further study and tests. The measurements show that a small copper or aluminum foil enclosure can effectively reduce the magnetic emission of the motor by between 50 and 85% at 73 kHz. This study compares the test results of the air pump motor with various cost-effective shielding materials. The data provided in this paper can serve as a reference for shielding enclosure design of the PDM air pump motor to reduce its electromagnetic emission as one form of EMI mitigation strategy.