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By A. Noble

Linear circuit analysis (LCA) is a fundamental tool which has been used to evaluate mineral separation circuits during the preliminary design phase. Traditionally, the LCA methodology uses the analytic circuit solution to determine the relative slope of the circuit?s partition curve. This value is then used as an indicative performance measure suitable for the comparison and ranking of alternative circuit configurations. Unfortunately, the partition curve slope only reflects the separation potential of middling material. In most mineral systems, this material represents a small portion of the initial feed (due to liberation) as well as a small portion of the revenue potential (due to the incremental value). Respecting these limitations, the authors have developed new separation performance indicators which may be derived from the analytical circuit solution and used in LCA problems. These indicators inherently reflect the separation potential of pure material, providing a better indication of lost revenue due to misplaced material. The complete methodology has been integrated with prior software to produce the Heuristic Optimizer for Resource Separation Economics (HORSE).

Feb 23, 2014

"Geometallurgy is a discipline that seeks to improve the sustainability of the extraction of metals and minerals by promoting the smarter use of non-renewable resources, better energy efficiency and greater use of renewable energy. To achieve these goals, development of innovative technologies and approaches are being developed along the entire commodity value chain, starting with exploration and extraction and extending to reuse and recycling. This paper discusses the geometallurgy of industrial minerals with special emphasis on kaolin, a versatile industrial mineral applied in ceramics, paper, paint, plastics, rubber, pharmaceuticals, cosmetics, ink, sealants, adhesives, sanitary ware, glass fibre, toothpaste, animal feed etc. Aspects of kaolin extraction in south-west UK are analysed from a geometallurgical perspective. While geometallurgy already features in kaolin extraction, its role can be significantly expanded by combining advanced in-pit characterisation and orebody modelling with integrated planning and control of the refining and calcination process. This paper highlights the importance of innovation in realising the full potential of geometallurgy.CITATION:Glass, H J, 2016. Geometallurgy – Driving Innovation in the Mining Value Chain, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 21–28 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By A. F. Saavedra, N. E. Richards, C. J. McMinn

"The aluminum industry in general and Reynolds Metals Company in particular have continued to support development work for improvement of the Hall cell design and for alternative processes for the reduction of alumina. The evolution of the Hall cell design will continue into the next century as a result of further development of mathematical models, sophisticated control systems and new materials for cell components. This paper discusses the areas in which the new generation cell advances will differ from the present day design. Additionally, Reynolds Metal s has supported work for the development of a carbo thermic process to reduce alumina. Theoretical work has indicated that this process could possibly have economic advantage over the Hall process. Several complicated furnace configurations have been proposed to provide the conditions for successfully reducing alumina. The results of small pilot scale operation and most promising furnace design are discussed. For comparison, projected capital investment costs and operation costs are discussed. IntroductionThe evolution of the Hall-Heroult process will continue into the next century. This evolution will be influenced by economics, more .restrictive environment and worker protection requirements, and technological development. These factors will also cause changes in the competitive position of alternate processes for aluminum production.Several aluminum producers have made major investments in alternate processes for aluminum production in the past three decades and there is continued support in some companies for improvements in the Hall-Heroult process and for alternate processes. The more visible development work in reduction technology, not aimed at significant process changes, is in the areas of higher amperage cells with bus bar designs to reduce harmful magnetic effects, more advanced and automated feed, voltage and electrolyte composition control, improved energy efficiency and sol id waste disposal . Efforts to bring significant change to the reduction process are being made in development of materials that can function as inert anodes and cathodes. These materials could lead to the development of reduction cells with multiple bipolar electrodes operating on oxide feed and fluoride electrolytes. Development work on new processes was reduced in the last decade by several companies because of economic and technological realities. Reynolds Metals supported work on a carbothermic process to reduce alumina and produce commercial pure aluminum. This work progressed through small pilot plant operation, and resulted in development of furnace designs and operation regimes. This paper reviews how this and other technologies could influence the reduction of alumina beyond the year 2000."

Jan 1, 1988

By C. A. Rowland

Wet grinding rod mills have been used for 50 years to grind ores and to make specification sand. The application of wet grinding rod mills is well understood. Until recently, there have been very few installations of dry grinding rod mills. The basic principles learned from wet grinding rod mills that were used in the application of dry grinding rod mills are 1. It is possible to extrapolate the performance of 5' and 6' diameter wet grinding rod mills into larger diameter rod mills with the larger mills performing as predicted. Wet grinding rod mills as large as 14' diameter (inside shell) by 20' long using 19.5' long rods are in use operating satisfactorily. 2. Wet grinding rod mills generally grind more efficiently when the fines are left in the mill feed than when the fines are removed from the feed. 3. Wet grinding rod mills produce little tramp oversize and generally can be operated in open circuit except when very close control on the top size in the product is required. When operated in closed circuit, the circulating load is normally less than 100%. 4. The power required for the desired grind can be accurately determined from the work indices obtained from rod mill grindability tests on the material to be ground. Where required it is necessary to, apply inefficiency factors for oversize feed and for larger or smaller than normal- ratios of reduction. Recent applications for rod mills have developed where it is required that dry grinding be used. These recent applications cover the grinding of 1. Lead sinter, lead slag and limestone. 2. Iron ore. 3. Silica for making glass sand. 4. Cement clinker. 5. Coke.

Jan 1, 1968

By C. Harry Benedict

This paper, describing the leaching practice at the Calumet and Hecla mills, Lake Linden, Mich., is one of a series on milling methods and costs being published by the United States Bureau of Mines. GENERAL DESCRIPTION The reclamation plant is located along the shores of Torch Lake at a slightly lower level than the concentrator itself. The entire location of the original concentrator, in connection with the present reclamation plant, has been ideal, lore particularly as the leaching and flotation departments are common to both units. After 15 years of operation and with the reclamation sands just a little more than half exhausted it would appear that the remaining life of the deposit could be worked by the present plan, without decided changes or renewals of plant or equipment.

Jan 1, 1930

By Donald E. Zipperian

The studies described in this paper have established that flotation conducted in a column cell provided with gas generation by aspiration into surface tension lowered water, may considerably increase the efficiency and particle size range of a flotation process. Operation of a DEISTER FLOTAIRE ® Cell at several Southwest United States flotation plants under continuous rougher, scavenger and cleaner conditions has demonstrated the main positive features to be: (a) higher capacity per unit volume than conventional flotation equipment, (b) improvement of flotation of plus 0.210 m particles, (c) improved flotation of particles minus 0.037 m.

Jan 1, 1984

By C Tickell

Achieving occupational health and environmental noise objectives is a major consideration in the planning or operational phase of resource development and industrial projects to meet the needs of the workforce and community and comply with legislative requirements. For material handling systems, ventilation plants, mobile equipment, process plants and fixed infrastructure, noise emissions need to be considered at the design phase. The preferred approach is to provide noise emission technical specifications, but in many cases this is not stipulated. An occupational noise requirement, such as ‘not to exceed 85 dBA at 1 m’, is often provided, but this will not achieve the required occupational or environmental noise objectives and may cause overly stringent requirements when they may not be needed. It should be noted that when developing the technical specification, measuring compliance needs to be taken into account as, in some cases, measuring may be very difficult or even not possible.This paper will discuss the requirements for providing an effective noise specification that ensures the environmental and occupational noise objectives are able to be achieved and that, once installed, compliance can be measured. It discusses planning such as when to set the objective, correlating the appropriate objectives for the environmental and occupational noise requirements, allowing for measurement tolerance, providing a suitable criteria and data format for the suppliers to respond to and methodology to measure compliance. Different phases of a project require different approaches to planning for noise management and these will be discussed in the paper. Examples from 35 years of industry experience will be included.CITATION:Tickell, C, 2016. Preparing effective specifications for occupational health and environmental noise objectives in mining project design and delivery, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 781–788 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

The Kiirunavaara apatite-magnetite orebody is about 4 km long and approximately 100 m thick sheet-like body, which lies roughly in a north-south direction and dips from the horizontal plane along its entire length, in towards the town of Kiruna. The origin of this orebody has been a matter of controversy, with both magmatic and hydrothermal origins proposed. Traditionally and for practical purposes this rich apatite-magnetite ore has been divided into two main types: low phosphorous ore (B-ore) and high phosphorous ore (D-ore). Further the low phosphorous ore is divided into the low alkali (B1) and the high alkali (B2) ore.

Jan 1, 2006

By J. F. McIlwain

Cobalt-base hardfacing alloys used for wear resistance consist almost entirely of metals largely imported into the United States. As part of an overall research program to help alleviate this foreign dependency, the Bureau of Mines has been investigating an iron-base alloy system as a potential replacement for cobalt-base alloys for some uses. To ascertain the melting ranges, thermal analyses were made of cast heats of alloys containing, in weight percent, 59-61 Fe, 16-19 Cr, 8-9 Ni, 1 Mn, 1 W, 1 Mo, 0.5 Cb, 0.6 Si, 0.3 C, and 0-12 stoichiometric TiB2. Powder alloys within this range of composition, prepared by mechanical alloying, were sized and applied to mild steel test coupons by nontrans-ferred-arc plasma spraying. The resulting thin coatings were >95 pet dense, with bond strengths of 35 MPa and hardness of 400 to 840 DPH. Abrasive and adhesive wear test data were compared to those of a plasma-sprayed cobalt-base alloy. A range of boride contents resulting in most promising properties was determined for further research.

Jan 1, 1985

By L C. Taylor

Both the U. S. Navy and the U. S. Army are interested in knowing more about the loading applied to vehicles which are unfortunate enough to encounter a detonation of a buried mine in the course of performing their normal duties. The Dynamic Effects Laboratory at the University of Maryland has been involved in small scale testing for ten years to assist the Navy and the Army in understanding the loads that are applied to personnel carriers when a buried explosive detonates beneath them. This paper describes results from small scale tests conducted to determine the loading mechanisms on target plates when subjected to loading due to the detonation of a buried mine in saturated sand, dry sand, and water. Transparent target plates were utilized in order to determine the loading process beneath a floor board on armored vehicles. Various charge sizes were scaled in the laboratory accordingly to a standardized full size threat encountered in the battlefield. Tests were conducted in saturated sand, dry sand, and water keeping the stand-off distance of the target and the depth of burial of the charge constant. In the case of water impacting a transparent PMMA plate the crack propagation was recorded and the crack velocity is determined. Additional tests were performed in saturated sand by varying the stand-off distance of the target but keeping the depth of burial of the charge constant. The small-scale test results could be scaled to full scale by using verified scaling laws.

Jan 1, 2016

By Fred D. Wright

A drill unit designed by Bureau of Mines engineers for testing various types of rotary bits has been in use since April 1950 at the experimental oil-shale mine near Rifle, Colo. The unit has a hydraulic drill and feed system, which provides the wide range of operating conditions necessary for adequate testing of drill bits and for obtaining data needed for the design of production scale equipment. Through the use of this unit, it has been proved that rotary drilling of vertical holes for mining the benches of the oil-shale mine is much cheaper than percussion drilling, and it is believed that in the near future the rotary drilling of horizontal blast holes in the top heading of the mine will prove equally economical.

Jan 1, 1952

By Lon Santis, Michael Swisdak, David Leidel, John Tatom

The Institute of Makers of Explosives (IME) and A-P-T Research, Inc (APT) have developed and released a quantitative risk management tool, IMESAFR (IME Safety Analysis For Risk), for the commercial explosives industry. Consequence algorithms in IMESAFR are considered state-of-the-art. Generally, they mirror those in SAFER (US Department of Defense Explosives Safety Board quantitative risk management software). The science behind the software has now been assessed for its maturity. Results have identified areas where additional test consequence data could improve predictions. To address these areas, full-scale testing programs to provide the needed data have been formulated. Proposed testing efforts include work to: (1) improve characterization of explosive articles now absent from SAFER, and (2) refine modeling of the Potential Explosion Site (PES) types, particularly small metal structures, also not found in SAFER. Goals of each program as well as requirements for conducting the tests have been established. Testing results are to be used to improve the algorithms and to further the state-of-the-art in risk-based explosives safety.

Jan 1, 2012

By B. Currie

Maintenance of quality electrowon copper requires an electrolyte which has suitable chemical and physical characteristics. The proper design and operation of the solvent extraction plant is essential to the quality of the electrolyte sent to electrowinning. An aspect that is not well appreciated is that the return electrolyte can have negative effects on the operation of the solvent extraction plant. Poor SX plant operation creates below optimum electrolyte conditions. High Eh in the return spent electrolyte can degrade the SX reagent with large decreases in copper transfer capacity and increases in internal entrainment. The synergistic interaction of the SX and EW plants needs a single-source design approach to address the interactions. The design elements in the SX and EW plants required to manage the electrolyte conditions are discussed.

Jan 1, 2014

By F Shi, W Huang, D Seaman, K Runge

High Voltage Pulse (HVP) technology is a novel process that could potentially be the step-change needed in ore processability in the mining industry. The propensity of high voltage pulses towards mineral-enriched ore particles during treatment makes this technology selective and has the potential to enable ore pre-concentration by size separation. In this study, the potential for pre-concentration of a low grade copper-gold ore sample subjected to HVP pretreatment is investigated and compared to that achievable after mechanical breakage in JKMRC’s rotary breakage tester (JKRBT). The data show that a better pre-concentration result can be achieved after HVP processing than conventional breakage. The gold pre-concentration potential is much better than that observed for copper. 4D HVP pre-concentration characteristic curves were produced to assess the metallurgical performance possible as a function of energy input. The case study shows that when targeting a nominal metal recovery of 90 per cent for gold, the HVP pre-concentration technique can split the low grade ore (0.9 ppm gold and 0.28 per cent copper in the feed size 26.5-37.5 mm) into two components – a low grade oversize material (0.3 ppm gold and 0.15 per cent copper) and a high grade undersize material (1.0 ppm gold and 0.3 per cent copper). The mass split to the low grade is 23 per cent. Under this mass split scenario, gold recovery to screen undersize is 90 per cent and copper recovery is 85 per cent. The HVP treatment of this feed size requires a specific energy (spark) of 2.8 kWh/t.There is further research that would be required before industrial uptake of the HVP pre-concentration technology would be possible. This paper also outlines the research challenges that need to be overcome.CITATION:Huang, W, Shi, F, Antonio, C, Runge, K and Seaman, D, 2018. High-voltage pulse pre-concentration study using a low-grade copper-gold ore, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 327–338 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By A. Noble

"In coal and mineral processing, several numeric parameters are used to quantify the separation performance of unit operations. For density-based separations, the partition curve is used as the starting point for many stages of diagnostic analyses. The curve is often quantified by its midpoint slope sharpness, and this single value is subsequently used for technical evaluation, benchmarking, and comparison. While this analytical approach does depict misplacement by relative density class, it inherently prioritizes middling separation and does not consider process economics or the micro-price value of individual classes. An alternative parameter, the organic efficiency, does indirectly consider process economics, but it does not reveal information on the root cause of lost revenue or misplacement. In this paper, a new analytical approach, the partition moment of inertia, is introduced. This parameter reconciles the technical misplacement data derived from the partition curve with the economic data derived from micro-pricing. The result is a new analytical procedure that promises better use of performance data. IntroductionPartition curves are commonly used in the characterization, evaluation and simulation of various physical separators. In mineral processing, partition curve analysis is routinely applied to hydrocyclones, screens, density separators and other beneficiation technologies that are based on intensive physical properties. Graphically, the partition curve depicts the recovery of particles as a function of the physical property on which the separation is based, such as particle density, size or magnetic susceptibility. Given the probabilistic nature of many real separators, the partition curve often exhibits a characteristic S shape (Fig. 1), similar to a cumulative normal distribution. Other geometric features of the curve are also depicted in Fig. 1, including the high and low closeout, or bypass, values; the midpoint slope; and the separation cut point, defined as the property value with 50 percent recovery.Partition curve analysis was originally proposed to evaluate coal washability (Tromp, 1937). Given the limited computational resources at the time, the analytical methods relied heavily on graphical construction and interpretation of the curve. Owing to the simplicity of calculation and interpretation, many of these graphical approaches are still widely used for performance analysis today. The most common calculations are based on the slope of the partition curve at the midpoint. Increased slopes correspond to enhanced separation performance, as a perfect separation exhibits a stepwise transition from 0 to 1 at the desired cut point, that is, an infinitely large slope. One common formulation of this slope, the Ecart Probable, Ep, is derived by evaluating the slope between the 25 and 75 percent recovery points:"

Jan 1, 2016

By Michael J. Friedel

As part of an investigation aimed at improving the health and safety and competitiveness of the mining industry, the U.S. Bureau of Mines evaluated the application of common offset radar profiling, using a 250-MHz ground-penetrating radar (GPR) system, for the detection of fractures in igneous rock. A series of radar reflection surveys were conducted to detect and delineate the extent of fracturing at various granodiorite and gabbro quarries and outcrops located in Minnesota. The application of radar profiling for detecting joints, sheeting fractures, shear zones, and depth to water table was demonstrated to be feasible with minimal processing. Radar reflection interpretations were verified by visual inspection of the rock mass and field mapping of local structure. The radar reflection section provides a simple, rapid, and cost-effective means for mapping of shallow (less than 10 m) small-scale fractures (greater than 0.25 cm) in igneous rock masses (characteristic of velocities between 0.061 m/ns for gabbro and 0.125 m/ns for granodiorite). Depth or distance estimates to fractures are within 10 pct of the actual, and time-shift compensation is necessary only when topographic irregularities exceed 30 cm.

Jan 1, 2010

By H. G. Iverson

Solid state reactions of manganese with silica were investigated in high-temperature tests. Reactions of 0.5 to 4.0 moles manganese (Mn) with 1 mole silica (SiO2) at 1,100° C and of 2.0 Mn:SiO2 mole-ratio mixtures at 1,000° to 1,150° C yielded products consisting of a slag phase and a metallic phase. At 1,100° C, the slag phase from reactions of the low Mn:SiO2 mole-ratio mixtures was composed of SiO2 and rhodonite (MnSiO3), and the slag phase from the high Mn:SiO2 mixtures was composed of MnSiOs and tephroite (Mn2SiO4). The metallic phase from the corresponding low Mn:SiO2 mole-ratio reactants consisted of two manganese silicides, Mn5Si3 and Mn3Si; from the high Mn:SiOg mixtures, it was Mn and the manganese silicide (Mn5Si). For the higher mole ratios of MnSiO2 the manganese content in the metallic phase increased, while the manganese and silica contents of the slag phase remained nearly constant. The slags did not contain free or uncombined manganese oxide (MuO). For the 2.5 to 4.0 Mn:SiO2 mole-ratio mixtures reacted at 1,100° C, the maximum quantities of silica reduced and of the manganese in the slag appeared to become asymptotical at about 41 and 48 percent, respectively. A brominating procedure was developed that was highly selective in removing the metallic constituents from the reaction product, leaving the slag phase as residue. X-ray diffraction patterns were obtained on prepared silicides Mn5Si, Mn3Si, and MnSi.

Jan 1, 1967

By Margaret R. Egan

A study of the combustion emission products of rigid ventilation ducting was completed by the U.S. Bureau of Mines. The ducting was composed of fiberglass-reinforced polyester resin. Four properties of the ducting were evaluated: (1) propensity to ignite, (2) smoke characteristics, (3) gas emissions, and (4) heat release. Particle sizes, obscuration, optical densities, and production constants for gas and smoke were also calculated. These results provide comprehensive data about the emission products, detectability, and relative hazards of fiberglass-reinforced plastic ducting and other mine combustibles under realistic fire conditions.

Jan 1, 1990

By Zhijing Zhang

A thermodynamic structure model for alkali borate melts is developed to describe the distribution of structural groups in the alkali borate melts as a function of compositions. Fractions of threefold coordinated boron atoms and fourfold coordinated boron atoms in the potassium borate melt are calculated for the entire composition range and compared with results reported in the literature. The model has been used for structural interpretation for the borate anomaly in viscosity, which regards the borate anomaly as a manifestation of the various antithetical effects caused by the introduction of alkali oxide into boric oxide. It has been found that the viscosities of alkali borate melts increase or decrease according to the changes in rigidity and spatial connectivity of the glass network structure, which is a function of temperature and composition.

Jan 1, 2001

Geostatistical literature has been dealing with recoverable reserve estimation techniques for the last 30 years. There have been well established support correction techniques (Le. affine correction, indirect log-normal correction, etc.) to deal with volume -variance relationship globally in determining what will be the reserves above a cutoff grade during mining. Kriging has become the accepted technique in the mining industry for ore reserve estimation. Many large companies are using this method for gold and copper deposit modeling. In general, the estimates coming from kriging are smooth. The variances of the block grades estimated by kriging are often lower than the material that will be mined selectively. As a result, kriging tends to under estimate reserves at high cutoff grades and overestimates them in low cutoff grades. It is necessary to perform additional steps after kriging if the goal is to determine recoverable reserves at some cutoff and not the in situ resources. In the mining industry, it is becoming more and more common for the low grade heap leach projects to consider whether the higher grade portion of a deposit may be processed by a mill at higher profits. Similarly, a concentrator -refinery operations are implementing heap leach -SX-EW option for the lower grade portion of their deposit. These options are making it very critical to estimate the low and high end of the grade distributions more accurately. Ore reserve estimation is normally done by using widely spaced exploration data which has very small size support (Le. core samples). Selective mining is carried out on ore control that is based on closely spaced blasthole data normally averaged into larger polygons based on some cutoff grade. Estimated grades from exploration data need to reflect the variability of the grades of the selectively mined units if they are used without further adjustments to predict recoverable reserves.

Jan 1, 1997