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By E. L. Chanturiya

During the mineral processing of pyrites sulphide ores of some deposits of Russia loss of gold with tailings and pyrite concentrates amounts up to 40%~90%. The problem of selective allocation of gold-bearing pyrite is crucial. There are 4 mineralogy-technological groups of pyrite determined in copper-zinc sulphide ores, based on the increase of contents of gold in pyrite. The gold associated with group 4 pyrite contents of 85% the total mass of gold found in the pyrite. The flotation behaviour of the enriched fractions of pyrite (98%), of the allocated from the ore of Gay deposit, were studied essentially in various conditions ?? and the charge of Butyl xanthogenate of potassium (ButX). Some products of selective pyrite flotation were investigated by methods of scanning electronic microscopy, energy-dispersive and X-ray spectral microanalyses, definition of specific resistance and thermoelectric moving force.

Jan 1, 2014

By Z. H. Zhang

Shizhuyuan is a world-class WO3, Mo, Bi and CaF2 poly-metallic deposit; it has rich reservation, but great difficulty in ore?s processing; thereby, for many years, it has been the target problem of beneficiation technologies. This paper, while briefly reviews its main scientific and technological advancement, pays special attention to the complete set of new technology and technical index achieved in recent years, which is characterized by using full-floatation flow-sheet as the backbone flow-sheet, explores some key factors influencing tungsten floatation, and presents a brief introduction to such new equipment as flotation column and comprehensive utilization of fluorite.

Jan 1, 2014

By Masakazu Niinae, Tasuma Suzuki, Mai Moribe, Yohhei Okabe

Bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 hour ON, 1 hour OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency.

Jan 1, 2014

By N. Schreithofer

Varying flow regimes, particle populations and consequently different types of bubble-particle interactions characterize the different zones of a flotation cell. The understanding of the role of the different zones of turbulent intensity on the particle-bubble interactions is of primary importance to optimization and scale-up of flotation processes and machinery. In order to study particle-bubble interaction in turbulent flow a completely new approach was taken. A laboratory scale stationary turbulence device was developed and built. The set-up allows the observation of particle-bubble interactions in various turbulence intensities, particle and bubble sizes and surfactant concentrations. The experimental set-up consists of a transparent, specially designed tank in which liquid flows between carefully designed and placed obstacles that create different turbulent flow fields. Bubble-particle aggregates are introduced into this turbulent zone. The behaviour of the aggregates, such as attachment /detachment of particles to/from air bubbles is recorded by a High Speed Imaging (HSI) system (5400 fps). The images are then analysed and the dependence of attachment/detachment process is described as a function of turbulent intensity in different conditions for different surfactant concentrations. This paper introduces this method to study particle-bubble interactions in turbulent flow and correlation to Computational Fluid Dynamics (CFD) simulation. CFD modelling is validated for two and three phase systems; liquid-gas with liquid and solid tracers respectively. The CFD simulations using the RANS k-S turbulence model showed good correlation to the experimental data and the experimental method is a promising tool for investigation of particle-bubble interaction in turbulent flow.

Jan 1, 2014

By Gamal Rashed

Coal bump is a sudden manifestation of the release of strain energy stored in a coal pillar (Peng, 2008). It is a very serious mining hazard that adversely affects the safety and productivity of the mines. Several case histories in mining have described coal pillars or faces of coal failing violently with an accompanying ejection of debris and broken material into the working areas of the mine (Campoli, 1987; Osterwald, 1962; Peperakis, 1958; Garvey and Ozbay, 2013). These failures resulted in large losses of life and total collapses of entire mine panels (Chase, Zipf, and Mark, 1994; Zingano, Koppe, and Costa, 2004). There are questions in the literature about whether or not the coal itself plays a significant role in bump. Rice (1935) mentioned that structurally strong coal is one of the key factors for bump; however, the strength of the Pocahontas #3 coal seam is low, and it bumped. Moreover, it is not obvious in the literature whether the strength of the tested coal samples is the inherent strength or if it is influenced by the shape or the size of the specimen. The main objective of this paper is to answer the following question: To what extent does the mechanical properties of the coal have an impact on the potential for violent failure? The best approach to answer this question is to compare the mechanical properties of two kinds of coals from bump-prone (Utah coal-Sunnyside seam) and non-bump-prone (WV coal-Sewickley seam). This comparison includes uniaxial compressive strength, modulus of elasticity, shear strength (cohesion and friction angle), and the burst index.

Jan 1, 2014

By I. Gombköto

To sustain the growth of industrial production necessitates the increasing of the amount of processed mined raw and secondary materials. As a side effect of raw material production, the amount of tailings material, - coming from mineral processing operations ? increases as well. Using wet technology, these tailing materials are generally transported and stored with the water used for previous operations. This habit could lead to dangerous situations. Enough to remember the disasters had happened to the last decade, safe tailings operations need to remove as much water from the solid as possible. Environmental, technical and economical needs should meet, therefore using a technology combining these specific needs could be necessary. Paste technology was introduced generally into tailings operations at the last ten years, as an answer to the call of the above mentioned challenges, however there are still many questions to answer within the frame of using it. The Institute of Raw Materials Processing and Environmental Process Engineering of the University of Miskolc has been dealing with mechanical process engineering, especially by the support of the EU project TAILSAFE Contract nº EVG1-CT-2002-0066 and the NKFP 3A/068/2004 Hungarian fund extensive research has been carried out about paste technology. Different test methods and materials were applied. Tested tailings materials were as follows: different fly ashes from coal power plants from Pécs ? Hungary, Gyöngyös ? Hungary, Neyvil ? India, different Croatian ashes, hazardous waste incineration plant ashes from Dorog ? Hungary, different kind of sands from Hungary, fine glass sand from Fehérvárcsúrgó ? Hungary, flotation ore processing tailing from Gyöngyösoroszi ? Hungary. Different additives, as gypsum, bentonite and cement were tested as well. The applied test methods were as follows: physical material testing (laser sizer, piknometer, different microscopes), X-ray diffraction analysis, settling columns, the three measuring pipes tube viscometer (16~27 mm pipe diameter), a hydraulic test loop with different pumps (40~53 mm pipe diameter, 0.2~4 m/s average slurry velocity range, 0%~52 % volumetric concentration range), rotational viscometer, Cassagrande yield locus tester and the slump cone test. This paper summarizes and systematizes the results of the aforementioned research as well as reports about the developed paste pipe transport design method based on the fine suspension ? coarse mixture model. The paper also reports about a systematic experimental series with different materials to establish criteria when high concentration suspensions behave like paste.

Jan 1, 2014

By Jochen Petersen, Caroline Muzawazi

The technical feasibility of ammonia leaching of PGM bearing Platreef flotation concentrates was investigated as an alternative method for the recovery of base metals prior to precious metal recovery. The composition of the concentrates includes 2.02% Cu and 3.17% Ni, and the major base metal minerals are chalcopyrite and pentlandite. Optimal leaching conditions were initially established in shake flask experiments to be a solution containing 4 M NH4OH, 4 M (NH4)2CO3 and a pH range between 9 and 10. These were used as base case conditions in column and batch stirred tank reactor tests, where the effects of total ammonia concentration and operating temperature were explored further. At optimal conditions nearly 100% Cu and Ni extraction were obtained in the batch stirred tank reactor, and 95% Cu and 60% Ni extraction was obtained in columns. The activation energy for chalcopyrite and pentlandite was 36 kJ/mol and 16 kJ/mol, respectively, in both reactors, indicating different reaction pathways for the two minerals. Gas-liquid mass transfer appears to be the limiting reaction step in columns much more than in tanks, and the degree of ammonia loss to air is significant. This initial test work indicates the feasibility of using ammonia leaching for this and similar materials as an alternative route to conventional smelting and refining prior to PGM recovery, but a number of technical challenges still need to be overcome.

Jan 1, 2014

By G. J. Arseneau

ABSTRACT Mineral resource statements are reported as tonnage (volume × density) and grades. Effort is expended to accurately estimate the volume and grade, but accurately determining bulk density is often overlooked. Oversimplification of density modelling can result in potentially serious errors in tonnage estimates and over- or underestimation of metal content. A reliable bulk density model requires an adequate database and a good understanding of density variability, along with grade and geology. In this paper, the author summarizes density measuring techniques, draws on examples of simple and complex grade-variable density domains, and discusses improved approaches for minimizing density estimation errors.

Jan 1, 2014

By Joshua Micah Hoffman

While it is easy to state that meaningful involvement of the community can play a critical role for a successful blasting operation, following through with this involvement is not an easy task. Structured Public Involvement (SPI) is a developed protocol for involving communities in project planning decisions and could be readily applied to the blasting industry. SPI was developed for the purpose of collecting quality public input about public transportation projects. The purpose of SPI is to bring about stakeholder satisfaction with potential projects by allowing controlled input from the stakeholders. It was designed and intended for democratic societies that have come to expect a voice in public projects. While blasting operations are not always in the domain of public projects, the fundamental process outlined by SPI can be useful for collecting feedback from the immediate public around blasting operations.

Jan 1, 2014

By Bengt H. Fellenius

"ABSTRACTAn example from a guidelines document for the Eurocode is discussed that addresses design for geotechnical strength of piled foundations in settling soil, generating drag force and downdrag. A modified example of geotechnical response is then analyzed in a failure mode, Ultimate Limit States (ULS), and stationary long-term state, Serviceable Limit States (SLS). It is shown that the Eurocode principles, when applied to correctly determined forces, results in an irrational and costly design. The results of the analysis of the modified example are applied to eight different codes pertaining to piled foundations from USA, Canada, Europe, and other countries. Several of the codes require that the drag force be included as a load in a ULS design, which an absurd and costly requirement, in some codes, in one case made even worse by combining drag force with live load. A major weakness of almost all codes is their minimal treatment and sometimes total absence of aspects of settlement of piled foundation. In contrast, my main argument is that design for capacity, whether in working stress approach, or by LFRD or ULS approaches, is not always safe unless a thorough settlement analysis shows that the design also meets the requirements of the SLS.1. INTRODUCTIONFirst, there were analysis, design, and construction establishing a State-of-Practice, SOP. Then, came codes and specifications summarizing the SOP, as interpreted by a committee. When the state-of-art, SOA, was not understood by that SOP-interpreting committee, the codes and specifications are uneconomical and, sometimes, also unsafe.The paper first presents an example quoted from two commentaries on the Eurocode 7 on design for geotechnical strength by the Eurocode (1997). The example is then modified to a more realistic case and analyzed in failure mode (ultimate limit states, ULS) and in the context of settlement (serviceability limit states, SLS). The analysis results are then applied to eight codes addressing piled foundation design and changes necessary for the referenced codes and specifications to be closer to the SOA are identified."

Jan 1, 2014

By D. Thibault, A. Akhiate, M. Brochu, E. Braud

Cast martensitic stainless steels, 13%Cr-4%Ni, having carbon contents between 0.018 wt% and 0.067 wt% were normalized, air quenched, and tempered at two different temperatures (550°C and 610°C). Their microstructures were characterized by optical microscopy and X-ray diffraction (XRD). Macro and microhardness, tensile strengths, and impact resistance were quantified for each material and condition. Results show that the prior-austenite grain size is constant through the materials but the percentage of reformed austenite, contained in the martensitic matrix, depends strongly on the material chemistry and on the tempering temperature and on its duration. It is observed that, independently of tempering conditions, an increase in carbon content increases the material hardness and tensile strengths, whereas the elongation remains constant. In contrast, the results of Charpy type impact toughness tests show a different trend. The material containing the average carbon content (0.034 wt%) is significantly tougher than the two other alloys. Surprisingly, the toughness of the steel containing 0.034 wt% carbon was found independent of the reformed austenite content. It is thus concluded that carbon and reformed austenite contents are not the only parameters affecting the toughness of these steels.

Jan 1, 2014

By Z. Pokrajcic

The traditional comminution circuit is a major consumer of energy ? both as electrical energy and through consumption of media and wear resistant liners. Up to 40% of electrical energy con-sumed at a mine site is attributed to comminution however only a few percent of this energy is used in the generation of new surfaces from size reduction. This paper describes the evaluation of modifications using simulation models based on two operating comminution circuits. The aim of these modifications is to decrease both the amount of electrical energy consumed in the size reduction process, known as direct energy, as well as to decrease the consumption of grinding consumables such as steel grinding media and mill liners, designated as indirect energy. The approach is two-fold: ??Employ, where possible, autogenous grinding techniques to eliminate the need for grinding media and reduce mill liner wear. ??Optimise the use of the grinding energy distribution in the comminution circuit by using more energy efficient grinding devices to target typically problematic features of a comminution circuit such as critical size material from the primary mill and overgrinding in the secondary mill. The investigations show that significant total energy savings, as high as 50% in some cases, can be achieved by employing the techniques described while maintaining circuit throughput and product size. Investigations also show potential benefits in downstream flotation processes as the product size distribution generated from the eco-efficient circuit is generally ?narrower? in shape for improved flotation performance and containing less material in the coarse fraction for overall better liberation.

Jan 1, 2014

By Y. X. Yang

Bottom ash is a solid waste stream in a Waste-to-Energy (WTE) processing plant during the combustion of the municipal solid waste (MSW). In the Netherlands, bottom ash contains typically about 18% metals originated from the MSW, and current industrial practice could recover about 10% metals through magnetic and eddy current separators. The remaining 8% as the finer particles is difficult to recover through current physical separation technology. Among various alternatives, vitrification is one of the promising options to immobilize the ash and recover the remaining metals. During vitrification a homogeneous glassy slag and a Fe-Cu based alloy were obtained. In the cur-rent study, the metal alloy recovered from the bottom ash originated from a Dutch Waste-to-Energy plant contains about 82 wt% Fe, 12 wt% Cu and 6 wt% other alloying elements and impurities such as C, S, P, Ni etc. The generated alloy does not have direct commercial applications, and separation of copper from iron-based alloy is critical to obtain the market value of both copper and ferrous constituents. To find a suitable processing route of this metal alloy, various alternative approaches have been considered for an efficient removal of copper from the alloy, and the focus in the present study was on the sulphide treatment at elevated temperatures of 1400 ~ 1500oC. The tested sulphide systems include pure FeS, FeS containing sulphide mixture (such as Na2S and Al2S3), pyrite (FeS2) mineral, ZnS containing sludge as an industrial waste. It was found that the carbon saturation of the alloy is proved to be an essential condition for a proper phase separation. The results showed that FeS mixed with Na2S, ZnS containing sludge and pyrite are effective sulphide systems for copper removal with a removal efficiency of 92% by using pyrite and 95% by zinc sludge at a S/Cu ratio of around 7 times of the stoichiometry. The copper content drops from 12 wt% to about 2 wt%. However, it is still difficult to remove copper completely from the alloy in a single step, and a multi-step operation is needed. The present research is expected to contribute both to the utilization of the metal recovered from bottom ash, and to the general recycling of steel scrap where copper removal from the steel scrap is a critical issue.

Jan 1, 2014

By Frederick Kuhnow

In open pit blasting, energy is released and transmitted through the geology. Negative effects can impact operations and can affect mine production. This paper presents recommendations for blast design to prevent damage due to ground motion from blasting on adjacent concrete structures of underground operations. It includes a case study describing a problem regarding an open pit mine expansion and asks whether production blasting will damage concrete shaft structures due to blast stress waves and blast-induced ground motion.

Jan 1, 2014

By Jae-Chun Lee, Rajiv Ranjan Srivastava, Min-seuk Kim, Byung-Su Kim

Recycling of spent hydrotreating catalysts (HTC) can potentially contribute towards the sustainable extraction of metal values. Treating such materials by hydrometallurgical methods to separate metals from the leach liquor of either acid/alkali media is a major step. In the present study, separation of molybdenum from HCl leach liquor of spent NiMo type HTC has been investigated by applying solvent extraction using Cyanex-923. For this, the chloride solution containing 973 mg/L Mo, 254 mg/L Ni and 1634 mg/L Al was taken as the aqueous feed. The parameters including contact time, concentration of the extractant, acid and chloride, and phase ratio were varied to investigate their effect on the extraction efficiency. The McCabe-Thiele plot suggests that > 99% Mo-loading using a 2-stage extraction process. From the molybdenum depleted solution, nickel was selectively extracted by Cyanex-301 leaving Al in the raffinate.

Jan 1, 2014

By C-D. Johansson, B. Ögren, B. M. Ludvigsson, K-Å. Johansson, R. Lindh, G. Berg, M. Maliarik

This paper presents the High Current Density (HCD) Silver Electrorefining Process. A 25-year history of development of the silver electrorefining process as well as associated equipment is given. The process is simple and robust, but at the same time highly automated. With low operating costs and man power requirement it allows consistent production of 99.99 % quality cathode silver. The process ensures that no toxic gases are formed in the working environment. Silver Electrorefining is a heart of a Silver Refinery plant covering the complete range of processes from casting of silver Doré anodes to casting of the bars of refined silver or/and silver granulation. The process has been successfully applied at 11 installations world-wide with plant capacities ranging from 30 to 1500 tpa.

Jan 1, 2014

By F. M. Zafar Kaifi

Magnesite producing companies rely on high grade purity MgO. The mineralogy of magnesite has a significant impact on the manufacturing of magnesite bricks. The manufacturing process of bricks companies utilizes 90% magnesite from 85%~90% MgO. The main objective of the magnesite bricks was to utilizes the indigenous raw material available in bulk quantity. With better under-standing of chemistry of the mineral species and strict control of bricks manufacturing/processing conditions can be better produce efficiently, a low cost high quality bricks with minimum detrimental environmental impact.

Jan 1, 2014

By Georgene Renner, Chee Theng, William Gleason

"With more than 900 booth spaces sold and 630 exhibiting companies displaying their wares, there was something for all 7,804 attendees on the exhibit floor of the 2015 SME Annual Conference & Expo in Denver, CO Feb. 15-18. The following is a sample of what was offered at the 2015 meeting.3D Laser MappingData collection and data analysis are changing how mining is done. One field in which technological advancements have made safer and more efficient operations possible is through site and slope monitoring.3D Laser Mapping, a United Kingdom-based company, was on hand at the 2015 SME Annual Conference and Expo to display its solutions for the mining industry, including its SiteMonitor4D system.The state-of-the-art laser measurementbased system was developed in partnership with geotechnical engineers and mining surveyors, and is a simple-to-use, reliable solution that has the flexibility and performance to function in a range of monitoring applications.The system measures and monitors the stability of rock faces, landslips and man-made structures, including ongoing, periodic measurement of volumes - stockpiles, cutbacks and waste dumps and has high-speed laser scanning for regular mapping of large areas by mounting the scanner on a vehicle.With specifications that other monitoring techniques cannot achieve, laser scanning opens up a new dimension in mine measurement and monitoring.www.sitemonitorsystems.comA.R. Wilfley and Sons Inc.Founded in 1919, A.R. Wilfley and Sons Inc. has been manufacturing dynamic-seal and static-seal pumps in Colorado for nearly 100 years, delivering its high-reliability, low-maintenance, heavy-duty process pumps and slurry pumps to the global mining industry. The family-owned company is now in the hands of the fifth generation."We are the dynamic-seal experts," regional sales manager Cesar Murillo said. "Most other companies are unable to do 100 percent dynamic seals and have to use mechanical seals or packing," he said, but Wilfley’s sealing technology does away with the need for mechanical seals and packing and their associated problems. As a result, solids and slurry handling capabilities are high, the pump can be run dry, and product dilution is eliminated. The pump can tolerate more misalignment, more cavitation, and more vibration in the pump during operation."

Jan 1, 2014

By Imre Gombköto, Zoltán Pap, Ákos Debreczeni, Sándor Nagy

Eddy current separators have become generally used in waste recycling industry during the last decade. There are many papers dealing with separation processes on eddy current separators, and also many article describes particle trajectory and different particle features affecting particle trajectory. These data are used in modeling as well. Within the frame of R&D project called ‚Fundamental research into the exploitation of the economic development potentials of critical raw materials in international co-operation - CriticEl?, authors are aimed for using Eddy Current Separator (ECS) as a mechanical separation step of high value critical elements recovery of selected WEEE’s like display panels, PCB’s. ECS, equipped with 305 mm wide belt, and a concentric magnetic rotor is used for experiments targeted development of methodology for determining separability of different particles on ECS. The subject of our work was to investigate the behavior of model particles with different shape, conductivity (aluminum and copper), orientation and size in order to separate Al and Cu according to the results of many experiments were carried out in this field. However it looks like that throwing distance of one particle is only possible to describe by a certain distribution for even the same particle within the frame of the same conditions. Sample mean and standard deviation are depending on some of the particle feature and acting forces. The paper is going to draft the first results on the relationship between distribution of throwing distance and particle properties.

Jan 1, 2014

By A. J. Dickson, A. M. Starfield

This paper reviews the progress made to date in the development of computer models of heat and moisture transfer from rock surfaces to the ventilating air in deep-level mines. The application of these programs to ventilation planning and design is discussed.

Jan 1, 2014