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By G. Jim Cardwell

The question "what constituents should be determined?" is one that defies a simple answer, because earth scientist being what you are, the rock and mineral analyst will eventually be called upon to determine about three quarters of the elements in the periodic table. The concentrations of these analyses will range from as low as 1 ppb to 100% of the material being analyzed. The most important thing to remember about a quantitative analytical result is that it can only be an estimate of the concentration of the analyte present. A measure of the reliability of that estimate is given by statistically derived statements of the precision and accuracy of the measurement. When evaluating your data an understanding of precision and accuracy are of paramount importance. Precision is the measure of agreement between replicate values while the accuracy of a determination is the concordance between it and the true value. There is no quarantee, however, that a precise answer is an accurate one. The numerical difference between the two values is the error. When evaluating your data, the repeats analyzed with your samples will identify the precision and control standards of U.S.G.S. or Canadian Certified Materials quality will identify the accuracy. The main problem is this data is routinely withheld from the report, or was it ever included in the analysis of your samples?

Jan 1, 1983

By Henry Rumfelt

Strip mining in the domestic coal industry is contributing a greater proportion of overall production than at any time in the past. U. S. Bureau of Mimes statistics show that the percentage of total production mined in 1958 by stripping methods in- creased to more than 30 pct, up from 22 pct in 1951. The tendency to favor strip and open pit mining exists in other mining activities, but such trends are not as clearly outlined as in the coal industry. Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating over- burden and dumping it in the spoil position where it remains indefinitely). Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating overburden and dumping it in the spoil position where it remains indefinitely).

Jan 1, 1960

By F. Kitzinger

The possibility of increasing the efficiency of mineral processing plants by means of computer control has prompted metallurgists to examine their flowsheets more critically in order to develop practical control strategies. Control schemes in use to date generally rely on the automation of traditional and previously manually regulated control loops, for instance the addition of reagents to maintain a constant assay or a constant pH. This approach is predicated on the availability of well-established primary sensors such as pH electrodes or on-stream analyzers. Noranda Research Centre, in cooperation with Noranda Group concentrators, has developed a froth level monitor and a pulp density meter susceptible of application in this type of control. Although some of the basic principles on which they are based have been known for some time, their incorporation into the design of reliable, direct-reading instruments which can be interfaced with a computer, is be-lieved to be novel*.

Jan 1, 1977

By A. Wang

This paper defines the elements of a basic economic model for decision-making when considering a methane drainage system for an underground coal mine. A drainage system will require significant capital and operating expenses; hence the decision to utilize drainage must be made carefully. The model outlines the basic structure of decision-making and considers the costs and benefits when the methane is marketed and when the methane is vented to the atmosphere. The effects on mine safety and the dust levels in the mine are also considered, both in a general format and as economic variables. Sources of information for executing this decision-making are provided for an actual mine decision.

Jan 1, 1997

By F. H. Nehl

The U.S. Bureau of Mines investigated the selective electrowinning of Ag and Au from cyanide solutions contaminated with Cu with the goal of decreasing the amount of Cu co-deposited. Decreasing Cu co-deposited will reduce refinery costs. Direct current was applied to the cell in pulsed and square wave voltages at 0.7 A?h per 150 mL of solution. Times tested for each cycle ranged from 1 to 10,000 ms. Graphite, lead, and stainless steel were evaluated as electrode materials. Square wave e1ectrowinning at 70? C gave the best separation of Ag and Au from Cu. Applying 2.5 V during the duty cycle, 0.0 V the rest of the period, a duty cycle of 10 to 30 pct, and a period of 100 ms to 1,000 ms gave the following results: Ag concentrations decreased from 34 µ g/mL to 0.1 µ g/mL, Au concentrations decreased from 54 µ g/mL to 0.2 µ g/mL, and Cu concentrations remained almost constant at 560 µ g/mL.

Jan 1, 1993

By W. D. Monaghan, G. L. Mowrey, C. W. Ganoe

In addition to developing various types of coal-interface detection systems, the US Bureau of Mines is actively involved in developing a coal rib-thickness monitoring system for high wall mining applications. One particular system that shows promise uses a ground-penetrating radar system to detect the coal-air boundaries of coal ribs. Based on preliminary laboratory and field tests, results indicate that this method can be applied successfully in highwall mines to maintain a constant rib thickness. The coal seam should be relatively clean in the vicinity of the antenna (e.g., have minimal partings or dirt bands) for best results.

Jan 1, 1996

By R. S. Shepard

A quick glance at a-portion of the title of this discussion -'Rolling With The Punch" may immediately lead you to assume that I am about to expound on the so-called manly art of self-defense. So that you will not have been misled entirely we will devote our considerations to a far more important art and if I may, I should like to begin by quoting Vincent Van Gogh. According to a literal translation the artist in describing one of his famous paintings said "these peasants are eating their potatoes with those very hands that dug them from the earth' and put them in the dish". Vincent Van Gogh may not have realized at that time, that he could likewise have been describing what is probably one of the oldest of all arts - the art of Material Handling - an art that man with the aid of science has tried to improve since the beginning of time.

Jan 1, 1963

By K. Wangerud, B. S. Caruso

A water balance model with deterministic and stochastic components was developed and used for the Gilt Edge Mine Superfund Site, South Dakota, to evaluate risks of contaminated runoff discharging to surface waters based on assumed water treatment plant (WTP) rates for different remedial alternatives. The objectives of the modeling were to use a stochastic approach for analysis of precipitation based on historic records, and for probabilistic estimation of annual and monthly runoff from primary disturbed/mining activity areas that currently requires, or will need, treatment at the WTP, water storage and changes in a major pit, and risk of contaminated water bypass of the WTP to a downstream drainage. Subareas/source areas generating contaminated runoff requiring treatment were delineated. A simple water balance model was used based on precipitation inputs and evapotranspiration and groundwater losses. Annual and monthly precipitation records for Lead, South Dakota were used to estimate precipitation at the mine site. A lognormal distribution was estimated for monthly precipitation. The stochastic software package/Excel add-in “@Risk” was used to generate random monthly precipitation values using a Monte Carlo method based on the distributions. The average annual and monthly distribution of pan and lake evaporation, and groundwater losses were also estimated for the site. Stochastic outputs from the model for the end of each month and year included contaminated runoff requiring treatment, water storage in mine pits and the risk of WTP bypass given different assumed WTP rates. The probability of the time required to dewater the pits was also modeled.

Jan 1, 2002

By L. Franko, S. Klima

Wet-drum magnetic separators are used extensively for upgrading iron ore and for magnetite recovery in dense-medium circuits. In this study the performance of a continuous, laboratory wet-drum magnetic separator was evaluated with and without the application of ultrasonic energy when processing dense medium slurries. Test variables included magnetic-to-nonmagnetic ratio, solids concentration, and nonmagnetic materials. The results indicate that under certain conditions, the purity of the magnetic material increased after ultrasonic treatment.

Jan 1, 2001

By B. K. Cantrell, K. L. Rubow

The US Bureau of Mines and the University of Minnesota have developed design and performance criteria for a personal diesel exhaust aerosol sampler for underground coal mines. These are based on the premise that size can be used to separate diesel exhaust aerosol, which is mostly submicron in size, from coal dust aerosol, which is mostly greater than a micron in size. The sampler has three stages: a respirable aerosol preclassifier, a 0.8- µm aerodynamic diameter inertial impactor to collect mineral dust and a final filter to collect the diesel aerosol. Using a sample flow rate of 2 L/min and gravimetric analysis to within 0.1 mg, the measure sub-0.8 µm diesel aerosol has an a-priori limit of detection of 0.3 mg/m3.

Jan 1, 1992

By S. S. Peng

A hybrid boundary element-finite element model was formulated to model roof bolt reinforcement of the roof strata with bedding planes. This model was used to analyze the stress distribution around a rectangular opening with variables such as opening width-height ratio, number of bolts installed, number/location of bedding planes, in-situ stresses, etc. The most critical areas are identified and the number and length of roof bolt required are then determined. Two case examples are illustrated.

Jan 1, 1989

By M. J. Oliver, A. J. Nugent

Hydrogen Peroxide and Caro's Acid (H2so5) were used to treat cyanide containjng effluents. Significant reagent savings were achieved by using Caro's Acid. Weak Acid Dissociable (W.A.D.) cyanides were removed at near stoichiometric levels of Caro's Acid. Hydrogen Peroxide showed poorer efficiency in the presence of W.A.D. cyanide complexes, resulting in higher consumption rates. By using Caro's Acid, reaction catalyst requirements ar(! el.iminatnd, react.ion I.imes significant.I y rnduced and capita] costs for an effluent lreal.ment facility are minimal. The Efflox* Process ut ilisc�s this more efficienl oxidising reagent in a treatment system exhibiting a simple non proprietary control system with minimal peroxygen consumptions.

Jan 1, 1991

By Leonard Harris

It gives me great pleasure to be here today to tell you a little about how Newmont Gold chose to use roasting at its Nevada operations for the treatment of its refractory gold ores.

Jan 1, 1992

By Ian Hutchison, Michael C. Salmon

TRC'S INNOVATIVE EXIT STRATEGIES™ FOR MINE CLOSURE , MINE "EXIT STRATEGIES™", WHAT IS AN EXIT STRATEGY™?

Jan 1, 1998

By Bodo Peinemann

For more than 35 years Lurgi has been providing its fluid bed roasters on a world­wide basis. The current total annual capaci­ty of the 250 Lurgi roasters approaches 26 million mt of sulphide minerals, including gold-bearing flotation pyrite concentrates. While the stationary fluid bed has been uti­lized for roasting exclusively, Lurgi has now commercially introduced its Circulating Fluid Bed (CFB) technology for gold roasting in a successful effort to maximize gold re­covery.

Jan 1, 1990

By Kwadwo O. Adutwum, George M. Potter, Todd J. Harvey

Ashanti Goldfields Company (AGC) is the largest gold mining company in Western Africa. Their jewel operation is a highly inte­grated set of mines and plants situated in Obuasi, in the Ashanti region of Ghana. This operation is responsible for mining 5.5 mil­lion tonnes of ore at 4.6 git annually from a series of open pits and underground mines. The sulphide ore is highly refractory with untreated gold recoveries in the range of 30-40%. The milling facilities are quite varied and include an oxide treatment plant (OTP), a heap leach, a sulphide roaster circuit (PTP), a tailings treahnent plant (TIP) and the most recent, a sulphide treatment plant (STP). The sulphide treatment plant, the world's largest stirred tank biooxidation circuit, was commissioned in early 1994. This plant treats approximately 800 tonnes of refractory gold con­centrate per day with overall recoveries of75-85o/o(ll, Biooxidation was selected for its ease of operation and less exotic maintenance requirements as well as its ability to achieve comparable gold recoveries. Unfortunately, despite stirred tank biooxidation being one of the lower cost methods of treating refractory ores, it is still too costly for low grade refractory materials. GeoBiotics, Inc. has developed a proprietary technology that allows the economic treatment of lower grade refractory gold ores through heap biooxidation. AGC has a significant resource of low grade refractory sulphide ore. This ore is too low grade to warrant BIOX™ sulphide treatment and its oxide plant recov­ery is low at 35-45%. GeoBiotics and AGC have completed pre­liminary testing and economic analysis of heap biooxidation for this material. Additionally, the feasibility of producing a gravity concentrate from the tailings of the sulphide treatment plant has been explored. This concentrate would be coated onto the low grade sulphide and biooxidized concurrently. Gold recoveries for the biooxidized low grade sulphide have increased to 75% and the gravity recovery from the STP tailings has achieved 80% uti­lizing a Falcon concentrator. The preliminary economics of the proposed full scale plant are very favourable with a pre-tax IRR of 233% and a payback period of 6 months. This paper details the biooxidation testing, flow sheet devel­opment and preliminary economics of employing heap biooxi­dation for low grade refractory ore treatment at Ashanti Goldfields' Obuasi operation.

Jan 1, 1998

By C. A. Fleming, C. J. Ferron, P. T. O'Kane, D. B. Dreisinger

The platinum group metals (PGM's) are typically recovered by flotation, smelting of the flotation concentrate to matte, and matte leaching. Concentrates too low grade to be processed economically by the conventional process require a new treatment route. PLATSOL, a new pressure leach process, was developed for the Northmet deposit and dissolves in one step base and precious metals (PGM's and gold). Various options exist to recover all pay metals from the leach liquor. The preferred option to date involves a solid-liquid separation, followed by sulphide precipitation of gold and the PGM's, and copper solvent extraction using commercial solvent extractants. This paper briefly summarises the process and the effect of the main leach parameters. Application of the PLATSOL process to various feedstocks is also presented.

Jan 1, 2000

By Barry Cloutt

Western Mining Corporation Limited owns and operates the St Ives Gold Plant located near Kambalda, approximately 90 kilometres south of Kalgoorlie in Western Australia. Production commenced in March 1988 at a design capacity of approxi­mately two million tonnes per year. The plant was quickly expanded as a result of new ore discoveries in the district and has been processing ore since 1993 at the rate of three million tonnes per year. The plant has recovered over 50 tonnes of gold since the operation began, The plant was able to maintain acceptable recoveries throughout the plant expansion phases. Further gains in recovery were possible since there was still free gold in the tailings after approximately 24 hours of leaching. Testwork carried out on prospective orebodies showed that some contained considerable quantities of free visible gold, while others were seen to be semi­refractory using a conventional grind - leach circuit. Alternative treatment techniques were considered because a substantial amount of revenue was lost with the treatment of these ore bodies using conventional milling techniquies. The basis for all the investigations was to maximise the gold recovery from each orebody while minimising the effective cost per ounce of gold produced,

Jan 1, 1995

By J. Potter, A. Anani, C. Antonio

This research aims to test the hypothesis that the low retention rate of women in the mining industry is caused by workplace culture and policies established due to gender segregation. A quasi-experiment is developed to determine the cause-and-effect relationship between gender segregation-inspired culture and the retention of women. The experiment considers the impact of the job type and the operational environment. The analysis provides information on factors that cause low retention of women in the industry, the extent to which gender segregation plays a role, and insights that allow actionable and measurable changes in the industry.

Feb 1, 2023

By R. Tamir

This paper will describe the benefits of utilizing the decision support system, DSS to support the methodology of structured decision-making in the mining environment. It will outline the layers of the mining related decision making – 1. Creation of “one truth” situational awareness utilizing 2. existing planning, ERP, operational and monitoring agents, a. Expressing plan verse performance across mining phases and functions compared with the actual and trends to evaluate performance. b. Creating alternate courses of action and the implications up and downstream. 3. It will review the current condition were although a multitude of technologies resolve multi variable issues they do not interact in a way that assists decision makers throughout the organization in making high-quality decisions that will push the overall performance envelope. 4. The paper will show the benefits of integrating military methodologies to resolve multi variable complexed issues (operational, financial and other), operating in changing environments in order to meet time sensitive objectives with restricted resources. This is achieved by creating a shared situational awareness thru incorporating information from a multitude of data generating agents, creating COA, selecting the appropriate and turning it into a plan. The paper will discuss the implementation and suggest a path.

Feb 1, 2023