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By Larry Stearns, Lori Tiefenthaler

Remediation of contaminated soil represents a significant market for application of Deep Soil Mixing (DSM). Eighty-one percent of U.S. Environmental Protection Agency (EPA) Superfund Program’s site remedies have involved contaminated soil. Contaminated soil is frequently treated by In-situ Solidification/Stabilization (ISS). ISS treatment of contaminated soil involves mixing binding agents into soil using DSM techniques. DSM is a core business for many DFI members. Members may improve and broaden their services to clients by learning about the recent ISS treatment of contaminated soil at a Superfund site. ISS treatment is part of the EPA-selected remedy for a Superfund Site in the metro New York City area. The property has seen heavy industrial use for more than a century. Soil at the site is contaminated with a variety of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) including coal tars and heavy metals, principally arsenic and lead. Beginning in 2017 and continuing through 2018, approximately 150,000 cubic yards (115,000 cubic meters) of soil will be treated by ISS at the case study site. Portland cement and slag cement are mixed into the soil by DSM techniques using GPS guided excavators to immobilize the hazardous constituents within the treated soil. ISS treatment by DSM will contribute to redevelopment of this valuable property. This paper will describe ISS constructability and performance, case study grout mix design with geotechnical results for strength and permeability, and deep soil mixing techniques. INTRODUCTION In-situ solidification and stabilization (ISS) is a deep soil mixing (DSM) technique applied in the environmental remediation field to physically encapsulate, or chemically bind, contaminates of concern such that the impacts to human health and the environment are mitigated. Common remediation applications of ISS include mixing cementitious reagents into contaminated soils to form a monolithic mass with desired performance characteristics, and the installation of vertical subsurface walls designed to control groundwater movement. A key characteristic of ISS is that the contaminated soils are treated in their existing location at the project site and then are left in place after treatment. Typical performance characteristics of the ISS treated soils include improved unconfined compressive strength (UCS), reduced hydraulic conductivity (HC), and reduced leaching potential of soil contaminants. Increased shear resistance of the treated soil may also be a performance requirement where seismic loading is a concern.

Jan 1, 2018

By S. Gaillard, E. Cauda

"Diesel particulate matter (DPM) is an occupational health hazard in underground mines. It generally occurs in the submicron range, and is often present in the mine atmosphere with significant concentrations of dust particles that tend to occur in the supramicron range. Since dust can interfere with analytical methods to measure DPM, it is often removed from a sample stream using impactor-type size selector (diesel particulate matter impactor, DPMI). Because the DPMI physically removes oversized particles from the stream, its performance may be gradually reduced with aging. Sharp-cut cyclones (SCCs) represent an alternative size selector for DPM sampling applications, with a major advantage being that, by design, they should not be susceptible to rapid aging. This paper presents results of a field study designed to compare the performance of aged versus new/clean DPMIs and SCCs in an underground mine. DPMI aging resulted in clogging of the device, and eventually a reduction of its effective particle cut size – though, when sample flow rate was maintained, DPM sample mass collection was not affected until significant aging had occurred. Under the conditions present for this study, effects of SCC aging were observed to be minimal by the end of the study period. INTRODUCTION Submicron particles are increasingly recognized as significant respiratory health hazards (Cantrell and Watts, 1997; Kenny, et al., 2000; Ristovski, et al., 2012). Diesel particulate matter (DPM) represents a major source of submicron particles in both public and occupational environments (Kittleson, 1998; Abdul-Khalek et al., 1998). Due to their work around large equipment in confined spaces, underground miners have some of the highest exposures to DPM (EPA, 2002; Grau et al., 2004). DPM largely consists of solid elemental carbon (EC), commonly known as “soot”, and organic carbon (OC) that may be sorbed to EC particles (Kittleson, 1998; Abdul-Khalek et al., 1998). EC and OC can be measured by thermal-optical methods such as the NIOSH 5040 Standard Method (Birch, 2016), and their sum is referred to as total carbon (TC). While the complex nature of DPM does not allow for its direct measurement, both TC and EC have been accepted as suitable surrogates for monitoring occupational exposures to DPM (Noll et al., 2007 and Birch, 2016)."

Jan 1, 2018

By D. Krawczykowski, D. Saramak, T. Gawenda

"Annual world zinc consumption is as high as nearly 14 millions of tonnes. Approximately 50% share of zinc is used for corrosion protection in processes of continuous galvanization and the hot dip processes. In the latter, two zinc containing residues are produced: zinc ash and hard zinc, which constitute around 10% each. Paper concerns the method of possible separation of metallic zinc from the non-metallic zinc compounds from the zinc ashes – the waste product of hot dip galvanization process. The investigative programme covered the comminution tests of the feed (zinc ash) in selected crushers: jaw crusher, roller crusher and impactor. Results of investigations show that application of individual crushing device results in various breakage of the feed sample. Impact force caused the highest increase in finest particles size fractions of the product, while metallic and non-metallic fractions were comminuted differently. The compression force, in turn, caused the selective comminution, i.e. the breakage of metallic zinc was observed in a higher degree. The presented approach appears to be an economical supplementary method of initial recovery of metallic zinc from metallurgical zinc waste. For the high demands for the zinc in the world and the need of corrosion protection, the method presented in the paper helps in more effective zinc recovery and environmental protection.INTRODUCTION AND METHODOLOGY World production of metallic zinc during last decade shows a slight increase and in recent years its consumptions reach 14 millions of tonnes. Figure 1 shows world production of zinc in the time period 2009 – 2016. Main directions of zinc utilization include: - Galvanization - Production of zinc alloys - Brass and bronze production - Semi-manufactures of zinc - Chemicals The major share in global zinc consumption constitute galvanization process (Bright 2007). Two main types of zinc galvanization are: hot-dip galvanizing (HDG) and electro-galvanizing."

Jan 1, 2018

By Ventsislav Stoilov, Angel Angelov, Ivan Korolev, Antti Remes, Todor Pukov, Stoyan Gaydardzhiev

"The process modeling and simulation studies aim for better process operation and favorable environmental impact. The objective of this work is to set up a simulation model of the Assarel copper flotation circuit for planning and optimization of the process with the aim of increased metal recovery. The model is parameterized based on laboratory flotation tests of ore samples from the Assarel mine together with mineralogical studies by X-ray diffraction (XRD) and Mineral Liberation Analysis (MLA). A combination of several techniques allows reliable identification of mineralogical composition of the selected samples. The changes in the proportion between sulfide minerals in various products along the circuit have been also documented. Further, this information is used in the simulation model and in data reconciliation procedures for establishing mass balance. The simulation accuracy is studied by comparing the simulations with the plant survey based mass balance. Constructed simulation model can be used to run alternative process scenarios. As an example, the flotation circuit performance with different reagent regimes is simulated based on data from batch flotation tests. Two reagents were considered for this purpose, dithiocarbamate-based one and xanthogen formate/mercaptan blend. It has been revealed that these reagents do not have the same influence on the selective flotation. The one improves flotation of gold and overall recovery but without notable selective action. In contrast, the other showed better selectivity towards copper, rejecting more gangue and lowering gold recovery. The model is also applicable for process optimization studies with different feed compositions, flowrates and circuit configurations. INTRODUCTION In the pursuit for elevated technological indicators, finding an optimal set of process parameters fully utilizing the potential of the equipment is a key factor to success. Over the past decades, there has been a substantial development in flotation circuit optimization through performance benchmarking using metallurgical modelling and steady-state computer simulation. Practical simulation engineering tools are based on experimental data obtained from laboratory tests and from plant surveys and operation data. With the help of flotation models, it is possible to study grade-recovery response with different feed compositions and throughputs, and with various cell-operating parameters, as well as to evaluate and design different flowsheet configurations. Outotec’s HSC Chemistry® software, which incorporates simulation and mass balancing modules alongside with several other tools, can assist with this optimization (Mattsson et al., 2015)."

Jan 1, 2018

By G. I. Voiloshnikov, V. E. Dementyev

"One of the most important advances in the world gold metallurgy is the introduction of adsorption technologies for processing of ores and concentrates. «Adsorbent-In-Pulp» process allows to eliminate pulp filtration that is especially important during processing of clay and slime bearing ores. “Adsorbent-In-Leach” process is one of the ways for processing of preg-robbing (carbonaceous) products. High efficiency, increased metals recovery, decrease in capital and operational costs, possibility of easy control and adjustment are the advantages of adsorption processes. Anion-exchange resins and activated carbons are used as adsorbents. This paper presents Irgiredmet experience on gold adsorption technology using both adsorbents (RIP, RIL, CIP, CIL processes). It includes results of long-term studies of different theoretical and practical issues of adsorption processes. Irgiredmet started development of ion exchange technology (RIP, RIL) in 1964. Laboratory and pilot plant tests were conducted to develop process design criteria for 15 RIP plants of the former USSR. During this test work a great number of newly synthesized resins including strong- and medium-base resins was studied, different types of adsorption feed (ores and concentrates) were tested; some theoretical regularities of adsorption process were investigated; the technology of two stage adsorption for silver gold ore, improved flowsheet for gold elution and resin regeneration, designs of technological equipment for adsorption, elution, electrowinning processes including pulsation columns, electrowinning cells etc. were developed. Irgiredmet took part in commissioning of practically all RIP plants in the former USSR. Due to its efforts RIP process became to be the standard technology. Last Irgiredmet RIP projects include the development of adsorption technology using medium-base resin for the three mines owned by GC Petropavlovsk (Amur region, Russia). The complex of the testworks on activated carbon gold adsorption technology including the search of prospective activated carbons; study on gold adsorption mechanism; development, testing and introduction of process flowsheets and the equipment for their realization was conducted. The original gold elution process was developed. The developed CIP technology was firstly introduced at Lebedinsky gold plant (Yakutia). Now carbon adsorption technology is widely used at Russian gold mines as CIP, CIL, CIC processes. The most relevant example of CIP introduction is Svetlinsky gold plant (Ural, Russia) with capacity 8 Mt of ore/ year."

Jan 1, 2018

By Sanjay Chaudhuri, V. K. Kalyani, Pradeep Kumar Singh, T. Gouri Charan

"Indian coal industry is the world's third largest in terms of production and fourth largest in terms of proven coal resources. Indian coal deposits are generally of high ash content varying from 24 to 50%. The coking coal reserves of India constitute about 12% of the total coal inventory, and the coals are washed in washeries, before being used for metallurgical purposes. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells. Extensive studies were carried out for understanding the performance of an operating conventional flotation plant. The performance studies revealed that appreciable quantity of clean coal is being lost in the tailings due to varied reasons and the required quantity and quality was not achieved. In this study, laboratory Flotation experiments were carried out to examine the cleaning characteristics of the said tailing and to determine the effective process parameters for recovery of clean coal at desired ash level ( 16-17%). Response Surface Methodology was applied to investigate the operating conditions of the Froth Flotation for modeling and optimization. Primary study reflects that there is a possibility to recover clean coal at 16-17% ash level with a yield of about 60-70% from that Flotation tailing of feed ash about 28%.INTRODUCTIONMost of the Indian coking coals are difficult in cleaning characteristics and high ash content due to its drift origin and its age of formation for more than 225 million years. Indian coking coal reserve is limited about 12% of total coal reserve. The minerals are homogeneously mixed with the coal macerals. The open cast mining practice and mechanized mining methods are being adopted to meet the increasing demands of coals resulting in generation of more coal fines and subsequently the quality is deteriorated. Indian good quality coking coal reserves of higher seams are fast depleting and hence coking coals of difficult cleaning characteristics of lower seams (LVC) are being now explored. Due to increased mechanization of coal mines to cope up the increased demand and followed by size reduction of lower seam coals in search of better liberation , the coal fines are increasing by leaps and bounds. The processes used for washing coking coal is Jigs, Heavy medium bath and Cyclones for the sizes upto 0.5mm, while the coal fines are washed in spirals and conventional flotation cells."

Jan 1, 2018

By Patrick J. Hannigan, Geir Veslegard, Frank Rausche, Rozbeh B. Moghaddam

A common type of deep foundation used in Norway to support bridge structures is the drilled pipe piles (piles) filled with concrete reinforcement after installation. The standard installation practice is the use of down-hole hammers. Complex geology and difficult subsoil conditions in Norway causes a high variability of soil and rock layers which in turn make for differences between actual subsurface conditions and those expected from geotechnical exploratory borings. This situation is strongly noted when the foundations are not fully socketed, and the rock layer is sloped. In this particular case, special testing procedures are required to assess the drilled pile base material and evaluate the rock-socket to ensure full contact between the foundation base and the rock surface. The local standard practice to verify the latter condition, consists of coring and visually evaluating the material recovered at the bottom of the drilled pile. This paper presents a case where the coring and visual inspection were not possible and alternatively the geological material encountered at the base of the deep foundations was evaluated using force-displacement measurements. Two 1016-mm (40in) diameter open-end drilled piles identified as P02-04 and P02-05 were tested and evaluated using in-situ force-displacement data prior to filling the piles with concrete. Test results showed an average displacement of 7mm (0.28in) corresponding to 35MPa (5.1ksi) stress level for P02-04, and 7.2mm (0.28in) corresponding to a stress level of 38MPa (5.5ksi). Based on testing results, both drilled piles were within the established material assessment criterion presented by the local authorities. INTRODUCTION This paper presents a case study in Norway where the material encountered at the base of an open- end drilled pipe pile (pile) was evaluated using force-displacement data. In the deep foundation industry in Norway, it is a common practice to install piles to support transportation structures. Once the piles reach the embedment elevation, and the pile base is assessed, these are filled with concrete. In projects where sloping rock is the supporting layer, and all nominal loads are supported by the pile base resistance, assessing the material encountered at the pile base to ensure full contact with the rock becomes critical. The local practice to make this assessment consists of the use of weighted tape, coring, or inspection cameras. However, similar to any other testing and evaluation methods, these come with their own limitations. The variability associated with the use of the weighted tape, accessibility for the coring equipment to complete a coring process, or the conditions at the foundation base such as murky water or thick drilling fluids could significantly impact the photo or video quality taken at the pile base. In such conditions, it is important to consider alternate testing methods to evaluate the material at the foundation base.

Jan 1, 2018

By Hillary Williams, Ronghao Li, Christopher Marion, Kristian E. Waters, Devin Hundt

"Zircon is an important mineral for ceramic, foundry, casting, and refractory applications; and it is the worlds primary source for zirconium. Zircon can also contain large and valuable proportions of other valuable metals, such as rare earth elements and hafnium. The Nechalcho deposit (Northwest Territories, Canad), is a hard rock REE deposit, which looks to recover zircon for its Zr and REE content. In this deposit, zircon is finely disseminated and associated with predominately silicate gangue minerals. Most of the work to date has focused on the beneficiation of mineral sand deposit, which typically remove silicate gangue minerals through physical separation steps. Therefore, the separation of zircon from silicate gangue, such as quartz, by flotation, has received little attention. This work used zeta potential measurements and microflotation experiments to understand the interaction between zircon and six different collectors (sodium oleate, sodium dodecyl sulphate, dodecylamine, SM 15, K-octyl hydroxamate and Florrea 7510). The results were compared with those of quartz. This study indicated that selective separation of zircon from quartz without the use of selective depressants or activators is likely challenging. The findings suggested sodium oleate and SM 15 only offered selective flotation of zircon in highly acidic conditions. Separation by the flotation of quartz is possible using sodium dodecyl sulphate, dodecylamine and K-octylhydroxamate. However, selective separation is highly dependant on collector dosage, for dodecylamine, and the selective activation of quartz, for sodium dodecyl sulphate and K-octyl hydroximate. Florrea 7510 offered poor recoveries for both zircon and quartz.INTRODUCTIONZircon (ZrSiO2) is a nesosilicate mineral which has a wide variety of applications, due to its hardness, opaqueness and resistance to heat and corrosion. Its major end uses are in ceramic, foundry, casting, and refractory applications (Bedinger, 2017). Zircon is also the most abundant zirconium (Zr) bearing mineral in the earths crust and is the principal economic source of Zr (primarily used in alloys for heat and corrosion resistance) and zirconia (ZrO2) (primarily used in ceramics) (Bedinger, 2017; Milnes and Fitzpatrick, 1989). Zircon forms in silicate melts and can often contain large proportions of other valuable metals such as rare earth elements (REE), and hafnium (zircon is the primary source of hafnium) (Bedinger, 2017; Belousova et al., 2002; Orlova, 2007). A common chemical formula showing the range of substitution in zircon is (Zr,Hf,Th,U,REE,Ca,Fe,Nb,Ta)(Si,P)O4 (Orlova, 2007)."

Jan 1, 2018

By S. V. Bogdanov, S. I. Grishaev

"The article presents the materials about the appropriateness of the use of rental indices to assess the effectiveness of the use of deposits of rare earth elements (REE). The authors suggest from the standpoint of rent payments to rate for the owner the possibility of using the anticipated rental income as the indicator for the analysis of preferences and economic significance of enrichment of extracted raw materials in the emerging field of rare earth metals (REE). Usually from ore mined at the fields, for flotation technology to produce concentrates with collective REE, then they are subjected to chemical-metallurgical processing of the received products are divided into pure oxides, chemical compounds or isolated from them pure metals and alloys. This commercial product is shipped to the buyer. REE were a non-renewable natural resources, so the calculations for determining differential and specific rent showed that during the development of the technologies of mineral processing of a specific field it is necessary to consider what the expected rental income depends on the magnitude of differential rent is related to the volume of production of REE for the whole planned period of exploitation of natural resources. This income is determined by the amount of stock field. For long-term exploitation of the deposit is observed in almost direct proportional dependence between the annual differential rent and the rental income. The decrease in rents in the long run is determined by the change in the composition of ores included in the extracted raw materials and the balance between light and heavy REE. The largest 70% reduction of the rent projected for ""cerium"" fields, while for ""yttrium"" these losses are considerably smaller. Tomtor, Chuktukon and Katuginskoye Russian deposits are characterized by a level of rent that is comparable to the mastered foreign sources of REE. Thus, the enrichment of minerals with REM in the domestic deposits is quite competitive at the world level. INTRODUCTION Deposits of rare earth metals (REE) are non-renewable resources that should be developed and used so that it would be possible to provide a reduction due to payment of appropriate resources for future generations. This compensation, due to the reduction of natural resources, can be carried out both in natural and in economic terms (1). When analyzing economic compensation options, particular attention should be paid to rental income in assessing the attractiveness of using different REE deposits. It is known that absolute and differential rents are summands when calculating the value of natural rents. The value of the absolute natural rent is proportional to the unit price of the product obtained from mineral raw materials and sold on the commodity market. Limitations, as well as the use in production processes and business, contribute to the gradual reduction of natural resources, which increases their consumer value and affects the price of commodity products from primary raw materials."

Jan 1, 2018

By Joshua Brien

DEEP SEABED MINING IN NATIONAL JURISDICTION: KEY CHALLENGES The talk focuses on the key challenges that arise from deep-seabed mineral exploration and development within areas of national jurisdiction, including legal and institutional challenge and options to address these challenges. Joshua Brien has acted for a range of Governments throughout the world, including smallisland States and the developing world. This has included engagement in matters before the International Court of Justice, the Tribunal for the Law of the Sea in contentious and advisory proceedings, including provisional measures applications and prompt release cases.

Jan 1, 2018

By J. Bouchard, A. Clapperton, L. Ebacher, N. Singh

"Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Froth flotation is used to produce nickel and copper concentrates. As is the case at other operations, the presence of magnesium is detrimental to the flotation products. In the past year, the exploitation of a new deposit has increased magnesium in the feed. Thus, it has been challenging to meet the required ratio in the final nickel concentrate. In search for a consistent solution for this problematic, an empirical flotation simulator making use of selectivity curves was developed. The circuit was expressed as a system of linear equations, which considered the distribution of copper, nickel and gangue minerals in the different streams. The relative quantities of each mineral are given by the separation efficiency curves of the various banks in the circuit. Three sources of data were used to calibrate the simulator: historical plant data (metallurgical balance), infinite dilution bench-scale flotation tests, and direct sampling of flotation cells. The calibrated separation curves were used to predict the recovery of the different species based on a single mineral recovery. Validation of the simulator showed good fit for the valuable minerals. The simulator was then used to infer the optimal operating conditions of the flotation circuit to optimise magnesium oxide content of the nickel concentrate. Simulation of two re-arrangements of the circuit gave a promising solution with a Fe:MgO ratio 2.42 times higher than the minimum value.INTRODUCTION Canadian Royalties Inc. owns and exploits the Nunavik Nickel project: a copper and nickel deposit in Nunavik, Quebec. Figure 1 shows the location of the mine site. After crushing and grinding, froth flotation is used to produce nickel and copper concentrates. The flotation circuit is designed with multiple stages consisting of bulk copper/nickel flotation, copper/nickel separation, and a separate nickel circuit (bulk float and cleaning)."

Jan 1, 2018

By M. Kadiyski, V. Stoyanova, E. Visariev, V. Stoilov

"The present study deals with copper losses in slag from copper smelting. Copper slag cooling at Aurubis Bulgaria is traditionally done in pits. A new type of slag-cooling is introduced in the site, involving cooling ladles. In a previous study, the ladle cooling process was studied in detail, showing an improvement in the recovery of copper in the slag after flotation. The main reason for better recovery of copper is the increased cooling time, which allows for the accumulation and aggregation of copper droplets. The effects of the newly introduced slag cooling process are studied using optical microscopy and scanning electron microscopy. Cooling in pits and in ladles is compared, based on copper droplet size, distribution and content. Specialized image processing software is employed on images taken with an optical microscope. The results are then compared with a similar technique, available in SEM software. The availability of phase-analysing image software in combination with electron dispersive X-ray spectroscopy makes it possible to study the morphological properties, distribution and chemical composition of the copper droplets. The obtained results confirm the initial conclusions about size, distribution and composition of the copper-bearing particles. A large amount of copper particles is examined showing an obvious increase in their size from pit- to ladle cooling. The results show an increase in the average size of the droplets, which doubles from pit-cooling to ladle-cooling. There is a well-pronounced tendency of decrease of the percentage of droplets in the smallest fraction (<5 µm) in the ladle-cooled slag. In addition, the number of droplets in the larger fractions increases, compared to the ones in the pit-cooled slags. It is believed, that the developed methodology for analysis provides a relatively quick and reliable solution for comparison of the cooling rates in the slag. INTRODUCTION In the process of copper smelting and converting, iron-silicate slags are produced that contain various amounts of dissolved and entrained copper. Different physical and chemical techniques are employed for the valorisation of the remaining metals in the slag – magnetic separation, leaching, roasting, flotation, etc. According to Gorai et al (2003), about 2.2 tons of slag is produced per ton of metal. In 2016, about 20 million tons of copper have been produced globally (www.icsg.org). At an average of 0.5 percent copper content after treatment, these slags contain more than two hundred thousand tons of copper which is lost due to inefficient processing."

Jan 1, 2018

By T. McCallum, C. Cooper, C. Lewis

"Following a successful solvent extraction (SX) pilot plant demonstration in 2016, CYANEX® 600 has been used commercially to recover molybdenum from concentrate leach liquor since March 2017. Consistent with the piloting results, the commercial plant has achieved expected molybdenum recovery, a significant reduction in base consumption, and a step-change improvement in physical performance. This paper highlights the optimization activities and plant performance from startup through normal operation. INTRODUCTION Historically, tertiary amines have been the most commonly used extractant for molybdenum and rhenium recovery. Tertiary amines utilize a protonation of the ligand combined with an anion exchange mechanism as proposed in equations (1-2). R3N + H+ ???R3NH + (1) 4R3NH+ + Mo8O264- ???(R3NH+)4Mo8O264- (2) In addition to the transfer of Mo and Re, the amine transfers acid and other anions to the strip liquor. The undesirable transfer of other species increases base consumption during stripping, impacting operating costs. Additionally, lower solubility of molybdenum-amine complexes create operational challenges, resulting in diminished physical performance. The presence of colloidal Si in concentrate leach liquors and the formation of Pickering Emulsions adds to the physical plant performance challenges with the amine extractant. CYANEX® 600, a phosphinic acid-based extractant, uses a cation exchange mechanism proposed by equation (3). 2(H2R2) + MoO22+ ??(HR2)2MoO2 + 2H+ (3) The cationic exchange mechanism eliminates chemical transfer of acid and other anionic impurities and avoids some of the physical challenges of the amine extractant (emulsion and 3rd phase formation). In addition, the reagent offers high selectivity for Mo over Re, which may be desirable in certain moly pressure oxidation (POX) flowsheets. Alkali base (ammonium hydroxide, sodium hydroxide, sodium carbonate, etc.) is used for molybdenum stripping. Therefore, reduction or elimination of chemical acid transfer from extract can significantly reduce base consumption in strip. Extensive laboratory and pilot plant testing was completed to evaluate the use of CYANEX® 600 for molybdenum recovery at Freeport-McMoRan’s Bagdad operation. The test work and pilot demonstration confirmed a reduction in base consumption along with improved selectivity. In addition, the evaluation highlighted a step-change improvement in physical performance over the incumbent amine extractant. The decision was made to convert the commercial operation to CYANEX® 600 in March 2017."

Jan 1, 2018

By Georgy Cherkashov, Livia Ermakova

Active development of the exploration and further exploitation of deep-sea minerals requires special emphasis on the protection of the marine environment. The complexity of this subject lies in the fact that potential impact and effects of future mining activity are not completely known. One of the main sources of potential impact near the seafloor, as it expected, would be a generation of sediment plumes, their dispersion and redeposition of sediment. Meanwhile, their dimensions, rates of dispersion and redeposition are a big issue. Other plumes are expected in the surface layer as a result of discharges of processing waters and particles after sorting on board of mining vessel, and their features are also not clear. At the same time, understanding of these aspects would be crucial for definition of environment impact area, delineation and designation of different types of protected areas (Areas of Particular Environmental Interest, Impact and Preservation Reference Zones) and future assessment of environmental impacts. Attempts to address these issues demonstrated wide variations between the data of field experiments on the one hand and the results of analytical and numerical models on the other. According to in situ measurements, plumes were detected at a distance vary from one to less than 20 km [e.g., Burns et al., 1980; Sharma et al., 2001; Nautilus Minerals, 2008 etc.], whilst some models show results up to 100 km [Rolinski S. et al., 2001] and more. It seemed that results of in-situ experiments are preferable, but they were not many indeed. However, these data were used in different investigations rather widely, but their focus, as far as we know, was not on the matters related directly with plumes.

Jan 1, 2018

By K. B. Han, S. Winkler, M. J. Benoit, M. J. Worswick

"Automotive heat exchangers are fabricated by forming multi-layered aluminum (Al) alloy brazing sheets into the desired geometry and subsequently passing the assembly through a furnace for brazing. As manufacturers seek to use thinner gauge and higher strength sheet to reduce vehicle weight, forming of the Al alloy sheets has become a challenge. Warm forming has previously proven to allay these forming concerns, but no consideration was given to the effect of increasing the forming temperature on brazing. Recently, it was shown that annealed sheet was more susceptible to the detrimental phenomenon of liquid film migration (LFM) during brazing if formed above 150°C, while work hardened sheets showed no increased susceptibility to LFM with increasing forming temperature, up to 250°C. In the current study, the brazing performance of simulated battery cooling plates was investigated. The plates were fabricated both from fully annealed and work hardened sheets. Brazing was assessed by microstructural evolution during a brazing cycle. The post-brazed microstructure varied with strain and forming temperature in plates made from annealed sheets, while no variation in microstructure with location or forming temperature was observed in plates formed from work hardened sheets.INTRODUCTION Since the 1970’s, one common method of fabricating automotive heat exchangers has been by forming multi-layered aluminum (Al) alloy sheets, and subsequently brazing the formed components together in a controlled atmosphere furnace. The Al alloy sheets used are comprised of at least two Al alloys roll bonded together, but can consist of additional layers, depending on the application; at minimum, the sheets are comprised of a core and clad layer. The core layer, often an AA3xxx alloy, remains solid throughout processing and provides strength to the assembly. The clad layer is always one of the AA4xxx series alloys which, due to their high silicon (Si) content, have a melting temperature range well below that of the core alloy. When the sheet is passed through the brazing furnace, the clad alloy melts to provide the brazed joint filler metal throughout the assembly, while the core alloy remains solid. In order to achieve cost and weight savings, heat exchanger fabricators have used Al alloy sheets with reduced thickness. However, deformation and brazing of these increasingly thin components remains a concern (Zhao & Woods, 2013). Furthermore, springback has been observed after forming sheets of higher initial strength (i.e. work hardened conditions), leading to flatness issues of formed components. Consequently, the ability to form high quality brazed joints is difficult in components formed from higher strength brazing sheets."

Jan 1, 2018

By A. Gueciouer, A. Akkouche, K. Chalah, A. Benmounah

"Drilling solid waste is a typical industrial solid waste, and it is a major pollutant source to ecological environment. Generally, waste management dewatering systems separate solids and fine particles from the liquid phase of drilling fluid, thereby leaving a clarified aqueous solution and allow the cleaning of waste fluids. Typically, dewatering waste management systems clean drilling fluid through coagulation, flocculation and/or mechanical separation. Chemicals used in dewatering are based on the coagulation-flocculation process, which it facilitate the removal of suspended solids and colloidal particles. The factors which can promote the coagulation-flocculation are velocity gradient, contact time, and PH. The objective of this work is to optimize a formulation adequate for dewatering based on the coagulation-flocculation process used coagulant (Aluminum sulphate), anionic flocculants (Partially Hydrolyzed Polyacrylamide) and anionic polyelectrolytes (in solid form with linear chain with very high molecular weight). The results obtained show the good efficiency of the coagulant and flocculants. INTRODUCTION Rig site dewatering of drilling fluids with recycling of processed water can help an operator to comply with environmental rules by reducing volumes of waste and reducing long term liabilities. It can also reduce disposal costs and provide a cleaner drill site overall. Most of the environmental concerns during the 1980s involved hazardous materials and toxic wastes. Drilling fluids, many of which are chemically benign, have escaped many of the difficult-to-comply-with rules and regulations. During the 1990s, however, operators may be required to submit a written plan for liquid waste reduction for even nonhazardous materials. Many states and local agencies may institute total bans on oil field wastes. Drilling rigs typically produce about 1 bbl of liquid waste for every 1 ft of hole drilled. Thus, a typical drilling operation can produce a large quantity of waste [1]. To improve the dewaterability of sludge, different pretreatment processes have been widely studied and developed including thermal, chemical, magnetic, mechanical, acoustic, electric, electro-acoustic and their hybrid treatment processes [2]. Rig site dewatering (figure 1) is the process of injecting coagulants or flocculating chemicals into the mud entering a large clarifying centrifuge. Coagulation occurs when the solid and allowing it to be attracted to other solids by van der waals forces. Flocculation is the binding of individual solid particles into aggregates of multiple particles. It is physical, rather than electrical, and occurs when one segment of a flocculating polymer chain absorbs simultaneously onto more than one particle [3]."

Jan 1, 2018

By S. Sheng, Y. G. Huang, W. Chai

"Polyacrylamide (PAM) is a typically synthetic depressant and may be used as a depressor of pyrite. The modification of polyacrylamide may improve its physicochemical properties and performances. Sulfonated polyacrylamides (SPAM) with different sulfonation degree (SD) were prepared using sodium sulfite as the sulfonating agent, and the interactions of SPAM and pyrite were investigated by the adsorption experiment in this work. The adsorption tests of SPAM on pyrite were conducted as a function of sulfonation degree, pH value and contact time. Pyrite and SPAM were constructed and optimized through MS software. The interaction mechanisms of sulfonated polyacrylamide and pyrite were simulated by molecular dynamics simulations. The results show that the adsorption capacities of SPAM at neutral and weak alkaline conditions are higher than that at acidic and strong basic conditions. The high sulfonation degree favors the adsorption of SPAM on pyrite surface. The adsorption process can be described best by the pseudo-second order kinetic model. Molecular dynamics simulations show that the adsorption of sulfonated polyacrylamide on pyrite is better than that of polyacrylamide. Sulfonated polyacrylamide can be used as a potential depressant of pyrite with the main interacting mechanism of hydrogenbond force.INTRODUCTIONPyrite is the most abundant sulfide mineral and often associated with valuable minerals such as galena, chalcopyrite, sphalerite, molybdenite, gold, diaspore as well as coal (Forrest et al., 2001; Jaiswal et al., 2015; Maier and Dobiáš, 1997; Qiu et al., 2017; Xin and Liye, 2010). Froth flotation is the most popular method to remove pyrite from valuable minerals. Pyrite could be floated as the flotation concentrate either by its hydrophobicity or activation by metal ions (Chandra and Gerson, 2009). What is more, pyrite could be seperated as flotation tailing by adding highly selective depressants including inorganic and organic modifiers. Polysaccharides polymers and lignosulfonate-based biopolymers are common natural organic depressants (Deng et al., 2017; Mu et al., 2016). While the synthetic organic products have proved to be particularly versatile in terms of molecule tailing capability and controlled structures (Boulton et al., 2001a; Raffa et al., 2015)."

Jan 1, 2018

By Wei Sun, Chengwei Li, Zhiyong Gao, Yuehua Hu

"Grinding for mineral liberation is a prerequisite for a successful flotation separation. Different grinding media produce mineral particles with different morphologies and surface properties. In this study, the surface physicochemical properties of fluorite particles produced by ball and rod mills were systematically investigated through single mineral flotation experiment, wettability measurement, X-ray diffraction (XRD) test and scanning electron microscopy (SEM) observations. The XRD observations reveal that the surface exposure degree for both mill particles follows the order {111} > {110} > {100}. The difference lies in that the rod mill ones have a higher exposure of more reactive {110} and {100} surfaces, leading to a stronger interaction with the collector. The difference also leads to their higher elongation and lower roundness values of rod mill particles which are beneficial for the particle-bubble attachment by shorting the induction time. The wettability and flotation results show that the rod mill ones have a lower critical surface tension and a greater hydrophobicity when treated with the collector solution and accordingly perform a higher flotation recovery. This work, for the first time, revealed the importance of the exposure of crystal surfaces in determine the shape factors and reactivity of the mineral particles and will help provide guidance for optimizing flotation separation and particle surface modification. INTRODUCTIONFluorite (CaF2) is the most important source mineral for producing F-based chemicals and materials which are widely used in industrial, environmental, and medical fields [1, 2]. In ore deposit, there are two kinds of occurrence forms of fluorite mineral. Firstly, the fluorite mainly coexisted with the gangue minerals like calcite (CaCO3) and quartz (SiO2). Because of their similar density and fine-grained dissemination in ore deposit, ball mill grinding before flotation separation has been widely applied to produce relatively fine particles [3]. Secondly, the fluorite is often associated with other valuable minerals with higher relative density such as scheelite (CaWO4) and cassiterite (SnO2). Due to their obvious density differences and coarsely grained distribution in ore deposit, rod mill grinding before gravity separation has been usually used to produce more uniform particles and avoid over-grinding [4-6]. After the gravity separation, a flotation separation is also employed to beneficiate the fluorite [7]."

Jan 1, 2018

By Richard Mills

Autonomous Underwater Vehicles (AUVs) are proven technologies used across market segments for survey, exploration and environmental monitoring tasks. When coupled with other autonomous platforms or sensor packages AUVs become part of an holistic system approach to exploration and environmental assessment and monitoring. Recent developments have seen AUVs deployed remotely with instantaneous access to data via the cloud. Our goal is to deliver the capabilities of each of these elements and present a cohesive data set with automated processing tools over a cloud based interface. nmanned Technology AUVs The HUGIN AUV System is the most commercially successful AUV ever built. Operated as a single vehicle, or as part of a swarm, HUGIN’s area coverage rate is unrivalled. Equipped with a comprehensive sensor package including Kongsberg’s synthetic aperture sonar, it collects a data set. Some of these data are processed in-mission to enable operators to readily access it when the vehicle is recovered. HUGIN is well suited to mining survey and exploration. Capable of reaching 6000 metre depths and conducting missions greater than 60 hours, HUGIN collects seabed sonar imagery, sub-bottom profiles, laser and camera images plus environmental data, with sensors running concurrently.

Jan 1, 2018

By Yu. E. Emelyanov, A. V. Bogorodsky, R. N. Nabiulin, S. V. Balikov

"The paper describes the results of the study of gold-copper flotation concentrate atmospheric oxidation at different sizes of material, varying oxidation time, with air or oxygen blow. The study showed the low rate of sulphide oxidation during oxidation of flotation concentrate at a feed size (P98 -74 µm). The coppery recovery into solution was 48%; the recovery of gold by subsequent cyanidation reached 86%. Preliminary flotation concentrate grinding to P98 -20 µm provided oxidation of 90% of copper minerals, 80% of arsenopyrite and 15% of pyrite. The gold recovery by atmospheric oxidation of a fine-ground flotation concentrate increased by 59%, from 36% to 95%, the NaCN consumption reduced by 21 kg/t, from 30 to 9 kg/t. INTRODUCTION Processing of sulphide gold-copper ores and concentrates using conventional cyanidation technology results in higher reagent consumption and lower gold recovery. Destruction of sulphide minerals and extraction of copper from a processed product prior to cyanidation is essential for improving efficiency of precious metals recovery and reducing main reagents consumption. Atmospheric oxidation (AO) is one of the most promising hydrometallurgical methods of refractory gold-copper concentrates processing, along with biooxidation and pressure oxidation. The nature of this approach lies in oxidation of sulphides at 90-95°C, in acidic or alkaline conditions, with bubbling of oxygen or air, after preliminary ultrafine grinding (1-4). The following reactions of sulphide oxidation occur during atmospheric oxidation of a gold-copper flotation concentrate. Pyrite is oxidized with the formation of ferric sulphate (1) and elemental sulphur at low temperatures (2), whereas some portion of elemental sulphur reacts to form sulphuric acid: FeS2+3,75O2+0,5H2O=0,5Fe2(SO4)3+0,5H2SO4; ?G=-1144,02 kJ/mol (1)"

Jan 1, 2018