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By J. Walden, J. Rhoades, R. E. Miller, R. Gibbs, P. Boman

Accelerometers and pressure transducers, mounted in suspension components, can be used to monitor the ride of haulage trucks. Presently, it is difficult to tell what caused a jolt to the truck using either pressure or acceleration data alone. When information from a global positioning system (GPS) is recorded at the same time as shock pressures or acceleration data, the exact location of an event can be determined. Mine management can then determine what caused the jolt to the truck. This research is part of a National Institute for Occupational Safety and Health (NIOSH) project called "Engineering controls for reduction of jolting/jarring injuries in surface mines." NIOSH is investigating how the work environment of haulage truck drivers can be improved. The US Mine Safety and Health Administration (MSHA) notes that, between 1986 and 1995, 60% of the back injuries were to haulage truck drivers in metal/nonmetal surface mining. Personnel from Phelps Dodge suggested that combining acceleration data with information obtained from a GPS could generate results with a variety of uses. Therefore, researchers at the Spokane Research Laboratory (SRL) began investigating how to tie acceleration and GPS data together. It was originally thought that this tool would be used primarily for road and truck maintenance. However, as research progressed, it became apparent that it would also be useful in providing feedback about equipment operations and identifying unusual causes of jolting. Experimental approach Available components that function well by themselves were linked for the purpose of proof of concept. Using a Modular Mining Systems (MMS) product called Vital Signs, SRL researchers took an Aero-Marine Products (AMP) acceleration recorder and hardwired it to MMS Dispatch equipment already installed on a truck. AMP is one of several manufacturers of acceleration recorders frequently used to monitor freight during shipping. MMS Dispatch is used for production accounting and truck dispatching and uses GPS tracking. Through Vital Signs, an analog or digital alarm signal can be recorded. Steve Rhoades, of MMS, wrote unique code that links the Vitals Signs data and GPS location and stores this data in an ASCII log file. SRL researchers installed the equipment in a Caterpillar 793 haul truck. The result was a working prototype. Figures 1 and 2 show the instrument installation in the truck. Discussion From 8:30 pm on Sept. 14, 1998 until 6:50 am on Sept. 15 1998, 899 jolts above a threshold of 2 g (1 g is the acceleration of gravity. It is either 9.81 m/s2 or 32.17 ft/ s2.) were measured on the test truck. Some sections of the haulage road produced most of the events, while

By Vance G. Leak

A technique for recovering copper and steel from metallic scrap has been developed by the Bureau of Mines based on preferential melting in molten salt baths at 1,150° to 1,250° C, The molten salt, preferably barium chloride or calcium chloride, both minimizes oxidation of the metals and promotes heat transfer. Cleanest separations (0.01 percent copper remaining in iron) have been achieved by pretreatment (dipping or spraying) with sodium sulphate or sodium silicate, which alters and coats the surface of the iron to inhibit the alloying or brazing with copper. An economic evaluation of the process was carried out on six combinations of sweating media and inhibiting reagents. On the basis of the postulated model, a cost of about $0.20 per pound of copper recovered has been determined for the sweating treatment operation.

Jan 1, 1973

By Jose R. Hernandez-Aguilar

"Three models to predict the effect of bubble size (Db) on metallurgical response were tested in a pilot-scale flotation column at Teck Highland Valley Copper mine. The column was fed with slurry collected from the Cu/Mo separation circuit. The first model was the one developed by Gorain et al. (1997), which assumes that the collection zone rate constant (kc) is inversely proportional to Db. The second model was the one proposed by Hernandez-Aguilar et al. (2010), which considers kc as an inverse square function of Db. The third model was the one developed by Yoon and Luttrell (1989) which provides expressions to describe the efficiency of particle collection (E) based on first principles. The results showed a significant bias between experimental and predicted data using the model of Gorain et al. (1997), possibly reflecting the model’s inability to explain the impact of bubble size, bubble rise velocity and flow regime on E. The model of Hernandez-Aguilar et al. (2010) well described the experimental evidence. The model of Yoon and Luttrell gave accurate and unbiased predictions. However, Yoon and Luttrell’s approach calls for a criterion to determine whether the flow regime is potential or intermediate, a subject that requires more fundamental research.INTRODUCTIONParticle collection, i.e., bubble-particle collision followed by attachment, is the basis of flotation. In a quiescent environment (such as the one observed in a column, or away from the impeller in a mechanical cell), a collision event can take place as long as the “degree of turbulence” caused by the rising bubble does not prevent particle and bubble to flow in close proximity. Upon collision, the particle slides on the bubble surface for a period of time. If the particle is hydrophobic, attachment occurs when the “sliding time” is longer than the “induction time”, which is the time required to thin and rupture the intervening liquid (usually water) film forming a three-phase contact angle. While the induction time is largely influenced by the degree of hydrophobicity of the particle, the degree of turbulence is governed by the bubble size. Generally, direct control of bubble size is not exercised by most mineral processing practitioners, in spite of its obvious importance. Studies to model the effect of bubble size on particle collection using fundamental approaches have been conducted (e.g., Anfruns and Kitchener, 1977; Webber and Paddock, 1983; Yoon and Luttrell, 1989; Dai et al., 1999). However, these models have been validated under highly idealized laboratory conditions (micro-scale experiments using single minerals and uni-sized bubbles), far from resembling those existing in practical industrial applications. Fundamental studies to interpret the effect of bubble size on particle collection in industrial environments are largely absent in the literature. Partly because of this lack of practical knowledge, many mineral processing practitioners perceive laboratory “bubble size” studies to be valuable academic exercises, but not something that can be directly applied to daily production issues."

Jan 1, 2011

By William Stewart, John Tinkler, Gary B. Hemphill

Of the 345 km long Taiwan High Speed Rail Project, connecting the cities of Taipeiand Kaohsiung, the 23 km alignment on Contract C230 required the construction of5755 m of shallow mined tunnels ranging from 137 m to 1285 m in length. All nine of these tunnels were mined using NATM methodology. On September 6, 2002, a collapse occurred in Tunnel T08 that affected approximately 50 m of tunnel. There was little warning. However, the crew was evacuated approximately 45 minutes prior to failure and thus, no injuries or loss of equipment. This paper will discuss the mining methods, jet grouting ground support, and the instrumentation selected for the rehabilitation and monitoring of the tunnel.

Jan 1, 2005

By M Kozikowski

The primary purpose of these investigations is to determine dewatering requirements and likely impacts associated with mining operations. Standard aquifer testing techniques were carried out at multiple locations within the Ord Range near Pardoo, Western Australia. Aquifer properties of an oxidised haematite orebody were calculated from test pumping data conducted in five fully penetrating test bores. Hydraulic properties of the Ridley magnetite orebody were calculated based on short term constant rate pumping tests, and packer tests. Packer tests were conducted in undeveloped and uncased exploration holes and diamond core holes. The new data sheds light on the hydrogeological properties of this previously unexplored region of Western Australia.Aquifer testing procedures for each bore included a preliminary step test followed by a constant rate test. Recovery data were collected in each bore over a period of four to six hours. Prior to testing, background water levels and water samples were collected in a network of monitoring and exploration bores to establish baseline water levels, gradients and water quality. Water quality within the bedrock of the Ord Range varies from 2000 to 5500 mg/L TDS whereas water quality within the alluvial sequence of the De Grey River is highly variable (400 to 2500 mg/L TDS), but is predominantly brackish with some water of potable quality which is used to supply Port Hedland. Test pumping supports the conceptual hydrogeological model that consists of a pod like orebody (aquifer) surrounded by low permeability waste rock (BIF), with very weak hydraulic connection to the adjacent alluvial systems. Calculated hydraulic conductivity from test pumping data across Pardoo ranged from 0.01 to 59 m/d, depending on deposit tested.A groundwater model was used to simulate dewatering required in proposed pits and to estimate the impact of dewatering on the surrounding shallow alluvial aquifers. Test pumping and numerical groundwater flow modelling indicate the proposed below water table pits can be successfully dewatered utilising in pit dewatering production bores. Yields from individual dewatering bores will reduce with time due to the reduction in saturated aquifer thickness.Based on the numerical groundwater modelling and field investigations the likely impacts to the adjacent De Grey River alluvial aquifer system (within the Priority 1 De Grey River Water Reserve) resulting from mining and dewatering activities is considered minimal. Recalibration of the groundwater model will be undertaken once several months of dewatering data are available.The aim of this paper is to present a range of aquifer parameters derived through standard aquifer testing techniques for an area previously unexplored in terms of hydrogeological characteristics. It is the goal of the authors to provide this comparison data set for future work in similar geologic media.

Jan 1, 2009

By A. Amiel

Tarkwa Gold Mine is owned by Gold Fields Ghana, IAMGOLD and the Government of the Republic of Ghana in a 71%, 19% and 10% ratio. The mine is operated by Gold Fields Ghana. This large, low-grade, open pit, gold mining operation is located in Tarkwa, in the Western Region of Ghana, approximately 320 kilometres by road, west of Accra, the capital of Ghana, West Africa. In the Financial year ended June 2007, the operation mined a total of 108 million tons of which 22 million tons was ore. The mined ore is processed through three gyratory crushers supplying two heap leach pads (north and south) and a carbon-in-leach (CIL) plant. Before the 6 Sigma project commenced, the current fragmentation was resulting in sub-optimal feed size to these crushers. It was decided to use 6 Sigma methodology to improve the fragmentation. A defect was defined as a fragmentation analysis indicating less than 95% passing 750 mm. The objective was to improve fragmentation in order to achieve a constant throughput to the north heap leach crusher of 1500 t/h, a 5% increase in pit loading efficiency and a 50% decrease in rock breaker hours, equipment damage costs and in-pit sheeting costs respectively. However, this was not to be achieved at the expense of grade control as Tarkwa is exploiting a low grade, high volume deposit and therefore ore dilution must be kept to a minimum. This paper is intended to take the reader through the various 6 Sigma phases of the project (define?measure?analyse ?improve?control), which have resulted in a 10% reduction in loading times, of which half has been attributed to improved fragmentation, as well as a substantial increase in blasted stocks. The focus has been on both drilling and blasting parameters as both processes had to be taken into account. These parameters are technical but personnel factors were also identified and dealt with as they arose. In order to measure the impact of any change in the process parameters on the fragmentation size distribution, cameras have been acquired. One has been installed looking into the bowl of the north crusher and the other one was dedicated to field observation, of individual blasts. Both are used for ongoing fragmentation analysis. At Tarkwa, mining efficiency is strongly dependent on good fragmentation as well as the presence of unblasted ?toes? on the pit floors. Crusher throughput depends on an acceptable ore fragment size. Compliance with plan for actual hole depths was temporarily monitored by manual hole dipping, but this is now being replaced with a fully automated drill data management system developed by Sandvik and Modular Mining. The Six Sigma methodologies, using control charts based on data collected in the field, allowed the mine to improve methods for the control of blasted material. It also enforced the implementation of a quality control programme encompassing the entire drill and blast process.

Jan 1, 2008

By Tim O’Neil

What prompted the merger of the two long-established American Mining Congress/National Coal Association (AMC/NCA) groups that combine the coal, hard-rock, industrial- and agricultural-minerals sectors of mining? Both associations have been facing similar stresses for several years - structural changes in their respective industries, the changing personality and role of government and well-financed and organized opposition groups. In 1993, the AMC board of directors undertook efforts at reorganizing the association. One board member, who serves on both boards, suggested it might be time to give serious consideration to merging the organizations. This is an idea that had been discussed more or less informally at least three times during my tenure at NCA. Negotiations toward a merger began after that and were consummated in February of this year.

Jan 1, 1995

Decision-making regarding plant-scale reagent dosage regimes and air rates is a topic of ongoing investigation and high importance. The current work explains some techniques that have proven useful in deciding on plant-scale flotation operating regimes. Specific focus has been placed on the reagents: frother and depressant, as well as some discussion around the control of air rate and froth depth. Air rate has been selected based on its effects on the froth phase. Froth velocity and froth height above the cell lip are the two variables measured and used to select the operating air rate. Pulp level is then adjusted to increase or decrease mass pull. A technique has been developed using the Anglo Platinum Bubble Sizer on an industrial flotation cell to determine the relationship between bubble size and frother concentration. This technique has been extended to measure the equivalent frother concentration or frothabilities of various streams on a rougher bank. A mass balance for frother was performed successfully, and this provided a better understanding of the way frother moved in the rougher bank. With this knowledge, more informed decisions can be made about frother addition required in subsequent flotation stages. For depressant, a new protocol for deciding on dosage rate has been developed. The depressant dosage should be based on the amount of fresh feed material reporting to a bank. Currently 400 g per ton of fresh feed has been assumed a reasonable starting point, with promising results. Improved froth stability and grades were observed. There is scope for more accurately defining the optimal dosage rate. Importantly, the combined effect of changing the chemistry and the hydrodynamics together has been demonstrated. A significant upward shift in the grade-recovery relationship for a cleaner bank was observed.

Jan 1, 2013

By A. E. Hall, R. N. Taylor, J. G. Taylor

The introduction of tunnel-boring machines to South African gold mines has created problems and challenges which accompany any new technique. This paper describes the experience gained in this field, especially in the design and erection of a tunnel borer and in boring and environmental conditions.

Jan 1, 1978

By Brian Hart, Roger St. C. Smart, James Francis, Mark Biesinger

"There are a number of challenges involved with the surface analyses of different mineral phases from process streams in a flotation facility. The first of course is to collect samples that are representative of the process and to ensure that they remain in a pristine condition prior to introduction into the instrument. In mineral processing, sample collection from the different streams is done on site and preservation involves simply removing oxygen from the sample by bubbling nitrogen or argon gas through the sample and snap freezing with dry ice.The second challenge in studying the surface chemistry of specific minerals is to find reliable methods of mineral phase recognition. In surface analysis of mineral particles confident mineral selection can be difficult with many multi-metal minerals (e.g. chalcopyrite, pyrite, sphalerite) and with precipitated, adsorbed, reacted and contaminant species in the outermost molecular layers.In this paper we show that principal components analysis (PCA) of ToF-SIMS data provides improvement in phase recognition, particle selection and associated variations in surface species. We will demonstrate, with specific examples, that this technique can be utilized to differentiate surface chemical factors promoting (hydrophobic species) or inhibiting (hydrophilic species) flotation.Species recognition based on the PCA method in a study of Cu transfer between chalcopyrite, pyrite and sphalerite mineral mixture clearly identified a statistical difference in copper intensities between the sphalerite and pyrite phases. A similar ToF-SIMS/PCA based study applied to concentrate and tails samples collected from the Inco Matte Concentrator demonstrated extensive CuOH and NiOH transfer between the chalcocite and heazlewoodite minerals. The statistical analysis has been able to confirm some mechanisms and deny others proposed to control recovery and selectivity giving more focus on the control factors.The ToF-SIMS PCA statistical analysis has elucidated differences in surface chemistries which illustrate the discriminating depressant action of adherent aluminosilicate (gangue) fine particles and adsorbed ions on the surface of sphalerite grains. In the flotation test concentrates, HIC conditioning resulted in the removal of these gangue fines thereby improving surface collector attachment efficiency, promoting a greater recovery of sphalerite."

Jan 1, 2007

By Muir DM, Ritchie IM, Gibbons SL

Fundamental studies on the transformations of iron oxides have been carried out and related to the solution conditions in the Becher Process. The results show that a number of iron oxide interconversion reactions occur in the aeration reactor with the products depending on the pH, temperature and oxidation potential of the aeration liquor. It is concluded that the lack of process control in the aeration reactor of the Becher Process significantly hinders the ability to predict and produce high quality single phase iron oxides of a consistent colour.

Jan 1, 1989

By William D. Hissem

While much technology has been developed and brought to bear in the area of blasting applications, the foundation work required for success in the muck pile begins with the drilling program.

Jan 1, 1997

By Gregory J. Chekan

This Bureau of Mines report presents three methods for designing bulkheads to impound water underground: (1) thin and thick plate design; (2) South African plug design; and (3) single and double bulkhead seal design. Related areas critical to the long-term effectiveness of underground water impoundments are also addressed. These include bulk-head anchorage, concrete specifications and placement, the grouting of permeable strata, and the sizing of barrier pillars. A case study involving hydrostatic tests conducted on a single bulkhead seal constructed in the Safety Research Coal Mine of the Bureau's Pittsburgh Research Center is presented in an appendix.

Jan 1, 1985

By Van H. Manning

The term war minerals has been applied t.o those ores and minerals that were largely imported. before the war. Among the mon important of these are manganese, essential for making high-grade steel for munitions and industrial use; graphite, for u,.akin1 crucibles; tin, for plating utAmsils and for bearing-met.al; mereury, used as fulminate t.o explode shells; pot.uh, for making fertilizer and explosives; tungsten and molybdenum, for high-speed t.ool steel; antimony, for hardening bul!et lead; chromite, for tool steel, for tan- , ning leather, and as a refractory lining in furnaces; magnesite, for :refract:A>ry linings; mica, as insulating material; platinum, for the manufacture of sulphuric acid and for electrical apparatus. When the United States entered the war it was clear that every ship would be needed and that the number available for importing minerals would be small. Hence a quick and thorough survey of domestic resources was necessary. . Throughout the war the scope and volume of the war-minerals work increased until it covered practically every mineral that was known t.o be or was liable to be in short supply.

Jan 1, 1919

By Elisa Alonso

Manufacturing firms that rely on finite resources have a stake in ensuring sustainable materials use. Higher material prices and uncertain material supply, consequences associated with scarcity, can be damaging to firms. Firms have a number of options to improve material sustainability including dematerialization, material substitution and recycling. However, these options require technological capability, capital investments and supply-chain infrastructure; firms may decide to make such investments only if material prices increase. Once decisions are made, the barriers and delays to implementing changes may harm firms. The impact of not reacting to changes in material supply on firms was examined for the case of different platinum-using industries. It was found that taking action is particularly important for firms when limited material availability leads to volatile market conditions. Industries can benefit especially if they ensure process flexibility and have options for changing their material use patterns.

Jan 1, 2010

By L. van Dyk

The project was aimed at evaluating the double-header trains implemented at Great Noligwa mine, looking at the changes from the old conventional trains to the new trains, and identifying possible improvements to obtain an even better and more productive tramming system. The methods used to evaluate the double-header trains at the mine included personal observations, time studies, personal interviews, technical research, safety analysis, cost analysis, production analysis, breakdown analysis, break test analysis, comparisons and working closely with engineering department and manufacturers. Issues that were evaluated are the improvements in safety, cost reductions, tramming congestion reductions, better efficiencies, labour optimization, enhanced driver safety and maintenance. Shortcomings of the double-header trains were identified and recommendations made to improve on the shortcomings. Findings of the evaluation study indicated the following: ?Drastic improvement on safety ?Extreme cost reductions ?Reduction in tramming congestions and bottlenecks ?Better tramming efficiencies ?Optimized labour placement ?Enhanced driver safety ?More effective maintenance. Although there is room for improvements, the double-header trains were implemented with great success at Great Noligwa mine. It is currently the preferred tramming methodology at Great Noligwa mine, and is also implemented at other Anglo Gold Ashanti?South Africa shafts. This tramming system has huge potential for growth, not only in Anglo Gold Ashanti, but in all other older mines that experience major tramming problems.

Jan 1, 2008

By Agnes Y. Lee

As part of the U.S. Bureau of Mines program to improve base metal leach systems, pressure leaching of galena (PbS) concentrates in fluosilicic acid (H2SiF6) solution was investigated. Lead extraction was 93 pct when PbS was pressure leached in H2SiF6 at 95° C with 2OO-psig O2 pressure for 40 min, using ferric nitrate [Fe(N03)3] as a catalyst. The effects of several catalysts, O2 pressure, time, and acid concentration on leaching were determined. The purified leach solution was electrowon to recover high-purity Pb metal. The H2SiF6 used in leaching and electrowinning can be recycled continuously. A flow diagram was proposed based on this investigation. Elemental sulfur (SO) was recovered from the leach residue by solvent extraction. A method was also developed for treating the flnal residue to segregate the important byproduct elements such as Ag, Cu, and Zn and enable their recovery by standard commercial processes.

Jan 1, 1990

By R. Benito

This paper describes the development of a life of mine schedule (LOM) for one of the world?s largest known sedimentary Copper-Cobalt districts located in the Katanga Province, Democratic Republic of Congo (DRC). A particular feature of the Tenke Fungurume LOM schedule is the considerable number of pits/phases for scheduling, each competing to provide the best ore available to a capacity constrained process facility. This paper discusses the main scheduling objectives and constraints, data pre-processing as a scheduling aid, the mine scheduling approach, and results and conclusions.

Jan 1, 2011

By Alvin Kaufman

To aid industry and Government in planning water developments the Bureau of Mines in 1963 canvassed mineral producers to determine water use in 1962. Water use by the mineral industry comprises only 2 percent of the water withdrawn by industry as a whole. The major water-using mineral industries are natural gas processing, phosphate rock, sand and gravel, and iron ore. Analysis indicated the following conclusions: 1. Total water use and new water intake is dependent on the quantity of material processed and the process water requirements of the particular industry or commodity. 2. Recirculation is dependent on the processing requirements of a particular commodity, the manner in which the water is used, cooling and condensing requirements in certain large industries, the quality of new water intake, and the need to treat new and discharged water. 3. Consumed water is dependent on the quantity of water recirculated, the temperature and humidity in the area, and the proportion of water used for cooling and condensing. 4. A threefold increase in water use by the mineral industry by 1985 is forecast.

Jan 1, 1966

By T. Tholana

South Africa hosts some of the world?s largest known resources and reserves of minerals that are strategically important to the global economy. The country?s mining industry contributes significantly to the national economy in terms of gross domestic product, export earnings, corporate tax receipts, remuneration earnings, and employment. Platinum, gold, and coal are significant minerals because they make the largest individual contributions to these economic indicators. Several factors impact the cash cost performance of operations that mine these minerals, thus affecting the future sustainability of these operations, which are generally ?price-takers?. It is therefore important that the cash cost performance of operations for these key minerals is analysed. Commercially available industry cost curves can be used for such analysis. However, some companies may not be able to afford to purchase these curves. This paper presents a simple Microsoft Excel® algorithm for constructing the curves. It also demonstrates how the constructed industry curves were used to analyse the cash cost performance of South African mining operations for the three selected minerals for the period 2007 to 2011, which included the 2008 global financial crisis. The analysis revealed that the operations were affected by several global and local factors during the review period. The work reported in this paper is part of an MSc research study at the University of the Witwatersrand. Keywords cost curve algorithm, economies of scale, cash cost performance

Jun 1, 2013