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By J. R. Allan

Loki Gold Corporation of Vancouver, B.C. is developing the Brewery Creek Mine, an open pit heap leach gold mine, 55 km East of Dawson City in Yukon, Canada. Mineable reserves are 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797 000 oz) of gold. Ore processing will employ a cyanide heap leach using run of mine ore. Permitting this mine has drawn significant attention because the heap leach technology, while proven in other jurisdictions, has not been used in Yukon. Engineering design of the heap leach was similar to that for heaps in more temperate climates, with the added issues of permafrost and cold weather operations. Solution balance with seasonal placement of ore and year -round leaching requires very large pond capacity for spring thaw conditions.

Jan 1, 1996

By Paul D. Tomlingson

Maintenance costs in the mining industry often account for as much as 18-20% of total operating costs and with the cost of labor and materials rising, they threaten to become an even larger percentage of the total. Yet, without an effective maintenance program costs can soar beyond what they would be without a program. In other words, when production equipment is down, there is no production and no product to sell in the marketplace. This cost of downtime in lost product far exceeds the actual cost of maintenance, which is defined here as labor and materials. Thus, mine management must have an effective maintenance program to avoid downtime and meet production targets. Attaining an Effective Maintenance Program Many mine management and operations supervisors believe that an effective program is a function of how hard they push maintenance. Yet, when vital production equipment is inoperable and production is lagging, no amount of pushing helps. In actuality, maintenance has little control over its own destiny and needs support from other departments to deliver good service. Success of the maintenance program depends on gaining control of those factors that directly influence maintenance. Consider the following. Organization-The maintenance organization must be structured for maximum responsiveness to production needs. Unfortunately, some needs are immediate and many are unknown in advance. The maintenance department has little control over them. These outside influences limit the department manager's ability to control his own organizational structure. Preventive maintenance procedures-Routine lubrication, equipment inspection, minor adjustments and the like are controlled mostly by maintenance. Yet, scheduling preventive maintenance depends also on the availability of equipment controlled by other departments. Planning-The purpose of planning maintenance jobs is to ensure that the best use is made of maintenance resources. If the production department creates an environment of running repairs and emergencies, there can be little planning. Even well-planned jobs will suffer if there is less than full cooperation in carrying them out. As a consequence, the maintenance department is not blocked from planning, but the value of its planning is reduced. Scheduling-Maintenance scheduling should be a joint effort. Although maintenance does the planning, production must agree to the scheduled maintenance of its equipment. Workload-As a service organization, the maintenance department has limited control over its workload because it must consistently respond to other department's demands. At best, maintenance controls only the fixed portion of its workload-utility work, janitorial service, maintenance shop work, and assigned repetitive and preventive maintenance duties. Unscheduled and emergency work are initiated by operations. Major maintenance actions require full cooperation. Labor productivity-The effective use of labor is tied to other key functions of maintenance. These include organization, preventive maintenance, planning, scheduling, and emergency work. An area type organization, for example, can often respond more quickly to immediate needs than a centrally controlled maintenance group. Yet, area maintenance can result in lower labor productivity unless tight control is exercised. One of the advantages of a good "detection-oriented" preventive maintenance program is early discovery of problems and better opportunity to schedule corrective work in advance. Under planned work conditions, use of labor can be more productive. Complete planning and scheduling can minimize time spent on each job, increase effectiveness of supervision, and improve labor productivity. Finally, if emergency work is minimized, there are fewer delays, less lost time, better coordination, and more productive use of labor. While labor productivity is an important factor in carrying out maintenance, it also is influenced by outside factors. However, few realize the impact of being able to improve maintenance productivity. By improving the productivity of 30 men from 30% to 40%, maintenance could accomplish the same work value as if it had added 7.5 men working at 40% productivity. 30 (1800) (40%) = 21,600 man-hr/yr 30 (1800) (30%) = 16,200 man-hr/yr Difference = 5,400 man-hr/yr 1800 (40%) 7.5 men Leadership-The maintenance department can have significant control over its own leaders, the front-line foremen, but they must

Jan 12, 1982

By Susan G. Bilhorn

A number of studies have been conducted in active and inactive mine environments using continuous monitoring and data acquisition systems to detect various parameters. In addition to the information obtained for research purposes, these monitoring systems can provide a means to remotely collect required information (such as radon daughter concentrations and air velocity) and control various conditions (such as fan operation and air door position) in numerous working sections of an active mine. Selection of detector locations and placement, which are critical to obtain the information and control desired while not inhibiting mine operations and influencing the detector readings, are covered in this paper.

Jan 1, 1984

By C. J. Lewis

Considerable amounts of the world's known reserves of elemental sulfur are found near the surface in areas of volcanic activity both active and inactive. Because such deposits cannot in general-be mined by the well-known Frasch process, and because other methods of recovery have not proven to be economically competitive except in isolated instances, at present these reserves remain relatively undeveloped. However, projections of world sulfur demand indicate that new sources of marketable sulfur will be needed in future years 2/, 19/. For this reason, recovery of elemental sulfur from these near-surface deposits is of continuing interest. Solvent extraction as an approach to recovery of elemental sulfur from open pit-mined ores of these non-Frasch deposits has received considerable attention particularly at the research and development level 3 /, 7/, l l /, 16/, 21/,23/, 29/ This method has been and continues to be attractive because it presents the potential of high sulfur recovery and purity of product coupled with a relatively simple process flowsheet in which low energy requirements and reasonable operating costs are thought to be possible. However, the physical and chemical characteristics of the native-sulfur ores, of elemental sulfur, and of the known solvents, have presented difficulties in the development of solvent extraction processes. Up to the present time, viable processes have not been realized within the framework of sulfur marketing conditions.

Jan 1, 1970

By E. R. Palowitch

On February 5, 1973, Eastern Associated Coal Corp began shortwall mining in their Federal No. 1 Mine, thus marking the first attempt in the United States at modern shortwall mining, i.e., using a continuous miner to extract coal open-ended from pillars 100 to 200 feet wide, under the protection of a self¬-advancing roof support system (1)1/. Since then, four additional shortwall faces have been operated. While the number of face-years of shortwall experience in the United States is limited, this experience has been anything but uniform. Differences in operator motivation, coalbed parameters, geologic conditions, panel dimensions, and face equipment all have contributed to a wealth of knowledge which can provide guidance for the design of future shortwalls. The purpose of this paper is to review the history of shortwall mining in the United States and to assess its value to the U.S. coal industry in terms of the health and safety of the miner, the percentage of coal recovered, coal production, worker productivity, and relative cost performance.

Jan 1, 1976

By G. L. Smit

The Buffelsfontein Gold Mining Company is situated in the Klerks-dorp district of the Province of the Transvaal in the Republic of South Africa, approximately 100 miles west of Johannesburg. Gold production commenced in January 1957 and Uranium treatment of residue slimes as a by-product started in July 1957. The mining property is 5435 mining claims in extent, the equivalent of 7,988 acres or 12.5 square miles. The mine was initially exploited by the Pioneer Twin Shaft System, consisting of a 26 feet diameter down-cast shaft and a 22 feet diameter up-cast shaft, sunk in the north-west area of the mine to cater for the hoisting and ventilation requirements for a milling rate of 150,000 tons per month.

Jan 1, 1964

By Raymond F. Moran

The history and development of the FMC Coke process has been reported in numerous presentations over the past 10 years (1, 2, 3, 4, 5, 6) but a short review is desirable, especially regarding the aspects that are influenced by the coal to be used. F'MC has been developing this process in pilot facilities since 1956 and in a modest sized plant in Kemmerer, Wyoming since 1960 (Figure I). This plant produces strong uniformly sized coke briquettes from a completely non-coking coal, namely Elkol, a sub-bituminous coal of the Adaville seam. Since operating commercially, over 300,000 tons have been produced, 90% of which has been used in electric phosphorus furnaces and some 10% of which went for trials in iron blast furnaces. We believe that this commercial use of non-coking coals is a unique experience in the history of coke manufacture.

Jan 1, 1975

By N. Damiano, C. Zhou, R. Jacksha, J. Srednicki

Modern electronic devices and systems used to enhance miner safety and health are becoming commonplace in underground coal mines. The ability for these devices and systems to function properly in the presence of electromagnetic emissions from other electronic and electrical devices and systems is not entirely understood. To investigate potential electromagnetic compatibility issues of critical mine electronic devices and systems, researchers from the National Institute for Occupational Safety and Health (NIOSH) are conducting surveys of electromagnetic emissions in underground coal mines. This paper presents the measurement system, methods, and results of electric field electromagnetic emission surveys conducted in three underground coal mine environments in the frequency range of 10 kHz to 1000 MHz. The survey data show that in some environments electric field electromagnetic emissions in underground coal mines approached or slightly exceeded limits as defined by other industrial sectors.

Mar 2, 2022

By P. D. Rao

Although phosphorus is a very important biogenic element, its concentration in coal is generally low. Phosphorus concentrations typically range from 0.001 % to 0.229% in raw coals of the contiguous 48 states. Some Alaskan coals in the Cook Inlet region contain horizons unusually high in phosphorus. A foot by foot analysis of deep drill core, containing 70 ft. of sub bituminous 'C' coal from the Beluga coal field, Alaska, showed certain increments contained as high as 17.03% P2O5 in the coal ash; 1.01 % P on a moisture-free coal basis. Crandallite has been identified by electron microprobe analyses as a phosphorus numeral in these coals. The authors could quantify calcium, barium, strontium and phosphorus concentrations from the coal attributable to crandallite. These high phosphorus coals provided a unique opportunity to study the association of phosphorus in coals using chemical fractionation for exchangeable cations and acid extractable elements. Since the source of high phosphorous horizons in Cook Inlet coals is attributed to volcanic ash, it is suggested that the profiles of acid extractable phosphorous concentration may be useful for coal seam correlations.

Jan 1, 1992

By P. Schumacher, M. Fein

"INTRODUCTION Newmont’s Twin Creeks operation, part of its Nevada operations, produces gold from two large open pit mines. Mined ore is processed at one of three on-site facilities: a refractory mill with two autoclaves, an oxide mill and heap leaching facilities. Twin Creeks also processes various off-site sourced concentrates and ore including high grade underground ore from the Turquoise Ridge joint venture with Barrick Gold Corporation. This paper discusses Twin Creeks’ strategic mine planning process which is part of an in-depth continuous improvement program called “Full Potential.” The process involves cost analysis, phase design validations, life-of-mine production scheduling optimization, mill blending strategy and stockpile management. Through this Full Potential strategic planning, Twin Creeks is creating significant value by increasing near term free cash flow and life of mine net present value (“NPV”) and achieving cost reductions. TWIN CREEKS OPERATION Twin Creeks is one of the major gold producers in Newmont’s Nevada operations (see Figure 1, 2 and 3). Located approximately 15 miles north of Golconda, Twin Creeks produced approximately 28 % of the Nevada operation’s 2013 gold production of 1.8 million ounces (Newmont 2014). The production included Turquoise Ridge sourced gold ore from the joint venture (75% Barrick Gold Corporation, 25% Newmont).At Twin Creeks, there are two large open pits, named Mega Pit and Vista Pit (see Figure 4, 5 and 6). There are 3 to 5 phases in Mega Pit and 2 to 5 phases in Vista Pit depending on the gold price assumption. There is also an underground exploration project at the bottom of the Vista Pit. Twin Creeks produces gold from a variety of ore types requiring different processing techniques depending on economic and metallurgical characteristics. To ensure the best use of processing assets, engineering and processing groups at Twin Creeks utilize a Mixed Integer Linear Programming (“MILP”) model to guide the flow of mine sequences and material routing to various process facilities (Kawahata, Schumacher and Hufford 2013)."

Jan 1, 2015

By Richard B. Berg

Chlorite veins in the Silver Star district (40 km southeast of Butte) were of little interest to those who were mining gold and silver in the late 19th century. It wasn't until 1975 that unusually pure magnesian chlorite of the variety clinochlore was identified from a ?talc? claim in this district. In 1977 tests by Cyprus Industrial Minerals showed that this chlorite was suitable for use in ceramics. Mining begun in that year continues. These replacement veins of chlorite in Precambrian quartzofeldspathic gneiss differ from the metalliferous veins to the northwest in both attitude and mineralogy.

Jan 1, 1982

By Stanley V. Lachmansingh

Bauxite can be regarded as a mixture of hydrated aluminium oxides the predominant constituent - and oxides of iron and titanium, silica and silicates. Heterogeneous and non-crystaline, most bauxites vary in average composition from one deposit to another both in terns of impurities as well as the proportion of Gibbsita and the Monohydrates Diaspore and Boehmite. Iron levels (as Fe2O3) can vary from less than 1% to as high as 30% with the alumina content ranging from 40 to 6o%,. Gore than 90% of all bauxite mined in Guyana is used as feed for the - production of refractory grade calcined bauxite. There are -however, several speciality grades used in various industrial applications and these are characterised by the quality of the bauxite in particular ;,with regards to iron and silica levels which generally have to be low. The main speciality grades are designated Refractory, Abrasive and Chemical. Bauxitte is also used in the production of nigh alumina cements,, activated bauxite end in the manufacture of electrical insulators.

Jan 1, 1977

By F. W. Brackebusch

Paste is a high density mixture of water and fine solid particles with a relatively low water content (10-25%) such that the mixture has a consistency as measured by the ASTM slump cone test from slightly greater than zero up to nearly 12 inches (305mm). Particles of different size classes will not segregate or settle when the paste is not being agitated or when it is stationary in a pipeline. Cement may be a component of paste. Larger particles of aggregate can generally be added to a paste without greatly changing the pipeline transport characteristics. A paste may bleed water slightly when it is allowed to be motionless for periods of up to several hours, but the solids do not become so dense that the paste cannot be easily re-fluidized. The dividing line between the definition of a high density slurry and a paste is not sharp. It is a practical matter that must be considered when designing a pipeline transportation system. If the pipeline is very short, there is very little risk of plugging the pipeline with a high density slurry when flow is stopped for short time periods. With longer pipelines the mixture must remain stable without motion for periods as long as several hours to avoid pipeline plugging. The fine particles in a paste mixture can be composed of mine tailings or naturally-occurring clays, silts and fine sands. The mineralogy of the particles thus can have a wide variety from quartz and feldspar to clays, micas and even salts.

Jan 1, 1993

By Greg Bold, Mahmood Khwaja, Yuannian (Jerry) Wan, Michael S. Schultz, William Simcoe

Beaver Creek Clean River Project will satisfy the consent decree requirements by capturing and treating combined sewage overflows. The project consists of, approximately, 2,700 feet of 30-inch trenchless pipe installation, a new screening/disinfecting facility, an expansion of an existing diversion structure, and a 72-inch internal diameter, 530-foot long mined tunnel. The tunnel portions are being progressed as early release packages. This paper presents the geotechnical exploration program and the subsurface conditions encountered; interpretation of the geotechnical conditions; and, approach to developing stand-alone packages for the tunnels to mitigate construction and schedule risks and continue to advance the project.

Jun 13, 2021

By G. Kazonich, S. L. McGill, J. W. Walkiewicz

Naturally occurring minerals and reagent-grade compounds were tested to determine their receptivity to microwave heating. The maximum temperature achieved for the samples and the time required to reach temperature are reported. A description of the microwave oven and a thermocouple technique that accurately measures and continuously records the temperature of samples during irradiation are reported. Extractive applications using the generated microwave data were investigated. Stress fracturing at mineral grain boundaries in a gangue matrix was shown. This should significantly affect grinding energy requirements and liberation properties. A method to produce a magnetic phase on pyrite surfaces, a method of using microwave heating to retort cinnabar concentrate, and a roast-leaching microwave treatment of chalcopyrite ore are described.

Jan 1, 1987

By T. J. Driscoll

The effect of coatings on the incendive properties of aluminum alloy 6061-T651 in air-6.4%CH4 was studied for collisions between rusted steel and both uncoated and coated projectiles with incident energies as high as 300 J (220 ft-lb) and velocities as high as 200 m/s (660 fps). These conditions were intended to simulate the rough handling of equipment in coal mines. The ignition probability using uncoated alloy projectiles increased with increasing relative humidity and appeared to be influenced by atmospheric ozone content. The incendive properties of both the uncoated and coated alloy depended on the type of rust used, but the dependence of the coated alloy was very different from that of the uncoated alloy. A number of coatings developed in the last 25 years were found to offer protection from ignition and to remain largely intact for occasional collisions or collisions randomly distributed over the coating surface, but probably not for repetitive collisions at any given point on the coating. These protective coatings utilize a hard anodized aluminum alloy surface coated with one or more layers followed by heat treatment of the coating. Coatings containing Teflon and MoS2 and thicker than 50 µm (2 mils) appear to be most effective.

Jan 1, 1987

By V. N. Kolesnikov

The gold-silver deposits of the northern Primorye region are located in the eastern part of the East Sikhote-Alin volcanic belt, where the belt overlaps the Kema island-arc terrain of the Aptian-Albian age. There have been four deposits and numerous mineralization points found in the NE-trending Kema metallogenic belt that is about 1000 km long and 100 km wide. The known mineralization is of epithermal type, controlled by faults, and concentrated in quartz, quartz-fluorite-adularia, and, less commonly, sulfide-quartz vein systems hosted by the Upper Cretaceous-Lower Tertiary volcanic rocks. The vein systems extend for hundreds meters along strike, varying from tens centimeters to 50-60 meters in width. They are surrounded by wide zones of low-temperature hydrothermal alteration containing some gold-silver mineralization for which the commercial value was not studied during the early exploration. The ore bodies contain from 1 to 50-80 ppm of Au and from 1 to 1000 ppm of Ag. Gold is native, associated with quartz, and represented by particles from tens of microns to 1 mm in size. Silver occurs in native form as a constituent of argentite, pyrargyrite, stephanite, and other sulfosalts. The test work carried out for three vein systems 20 years ago showed that gold might be easily and almost completely recovered from the ore by cyanide treatment. The paper describes the geology and mineralogy of the deposits, Salut and Primorskoye, that are the most studied properties of the Kema belt. It also presents the data available on disseminated gold-silver mineralization in stockworks, altered explosive breccias, and wide zones of low-temperature hydrothermal alteration. This mineralization should be explored for possible exploitation as large open-pit, heap-leach deposits.

Jan 1, 1998

By C. P. Newman, T. Gray, G. Beale, T. Cluff

Predictive geochemical and limnologic modeling of pit lakes is an important aspect of modern permitting. One of the key assumptions of many predictive pit-lake models is that highwalls and pit backfill become unreactive once submerged by the filling pit lake. Existing pit lakes provide useful data to test this assumption. The Sleeper pit lake (northwestern Nevada) is near hydrologic equilibrium and contains good-quality water that generally meets regulatory requirements for pit lakes. Despite the overall stable geochemical composition, seasonal trends in the hypolimnion indicate the generation of solutes and fluctuations in pH. This work applies mass balance, analysis of subaqueous pyrite oxidation, and trends in solute concentrations to evaluate the potential causes of long-term solute generation in the hypolimnion of the Sleeper pit lake. Results will aid in refining the effect that inundation of highwalls and waste rock has on ultimate pit lake chemistry and long-term closure planning. In the case of the Sleeper pit lake, ongoing solute loading does not substantially change the closure plan at this time as influent groundwater contains abundant alkalinity. INTRODUCTION As mine pit lakes become more widespread, regulatory agencies are increasingly requiring advanced predictive modeling of pit-lake geochemistry during permitting. The end goal of all those involved in these permitting actions (i.e., the mining company, the regulatory agencies, and the public) is to have pit lakes become geochemically and hydrologically stable for the long term, which may then allow mining permits to be relinquished. The modeling endeavors therefore are important to inform long-term closure of pit lakes. The conceptual models and numerical methods used to predict pit-lake water quality are complex and require substantial amounts of data and a variety of assumptions (Castendyk et al., 2015). One of the common modeling assumptions is that solute generation via acid mine drainage is eliminated (or at least decreased) by the filling of the pit lake and inundation of highwalls and any in-pit waste rock. However, few studies have reported on observations that support or refute this assumption. The water-quality record of the Sleeper pit lake is an ideal dataset with which to test these assumptions. The former Sleeper mine is located in northwestern Nevada (Fig. 1), and has been inactive (in terms of ore extraction) since 1996. The mine extracted Au and Ag from the famous high-grade Sleeper vein and associated widespread stockwork mineralization (Nash et al., 1995). Water quality in the pit lake has been monitored since the cessation of dewatering in 1996. The current pit lake actually occupies three separate sub-pits, the Sleeper, Wood, and Office pits (Fig. 1). The Sleeper and Wood pits undergo regular water-column monitoring using a conductivity-temperature-depth (CTD) probe, and sampling for dissolved inorganic constituents at several depths (~10, ~130, and ~330 ft. below lake surface). Groundwater quality is also monitored using a series of wells (Fig. 1).

Jan 1, 2019

By Arthur A. Brant

Your chairman has asked me to deal with questions of education relative to our present and projected trends in the field of mineral expiration. First comes our definition of education--and education is not the merely formal acquiring of academic knowledge, but the understanding, using and projection of knowledge into our channels of life and thought activity. This past year makes us realize the extent to which price and economic cut-off may stimulate or curtail exploration,, But exploration does not consist solely in the discovery of sources of material. There is just as inspiring and imaginative a territory in the develop¬ment of uses and application--and no one in our base metal industry but would hope that our educational processes would fertilize those springs of inspiration that lie dormant in us all, toward the- imaginative conception of new uses--lead roofing cloths or felts, non-tarnishable copper utensils, further zinc solid state application. Thus an educational pattern should seek to develop imagination and thinking beyond--the possibility of that small but oh so difficult step just ahead of the existing,

Jan 1, 1959

By R. Bryce, T. J. Doughty, K. Stoll

Sulfate-impacted mine waters are under regulatory scrutiny to reduce total dissolved solids (TDS). There are several options to reduce TDS. One option is transforming the soluble sulfate into insoluble ettringite. The Water Company LLC (TWC) patented a process for sulfate removal through ettringite formation by reacting directly with metallic aluminum. Freeport-McMoRan (FMI) and TWC have collaborated to design, build and operate a 10-gallon-per-minute (gpm) ettringite pilot plant to establish reagent consumption, plant availability and full-scale design criteria. Using metallic aluminum as the primary aluminum source for ettringite precipitation eliminates the addition of other ions, resulting in significant demineralization. The pilot plant achieved greater than 98% water recovery, greater than 90% reagent efficiencies and maintained reactor sulfate levels below 250ppm. BACKGROUND Ettringite is a hydrated calcium, aluminum, sulfate mineral with the following formula: Sulfate-impacted mine waters are under regulatory scrutiny to reduce total dissolved solids (TDS). There are several options to reduce TDS. One option is transforming the soluble sulfate into insoluble ettringite. The Water Company LLC (TWC) patented a process for sulfate removal through ettringite formation by reacting directly with metallic aluminum. Freeport-McMoRan (FMI) and TWC have collaborated to design, build and operate a 10-gallon-per-minute (gpm) ettringite pilot plant to establish reagent consumption, plant availability and full-scale design criteria. Using metallic aluminum as the primary aluminum source for ettringite precipitation eliminates the addition of other ions, resulting in significant demineralization. The pilot plant achieved greater than 98% water recovery, greater than 90% reagent efficiencies and maintained reactor sulfate levels below 250ppm. BACKGROUND Ettringite is a hydrated calcium, aluminum, sulfate mineral with the following formula: Ca6Al2(SO4)3(OH)12•26H2O Ettringite readily precipitates in high pH water and by doing so, removes sulfate from impacted waters. The SAVMIN process, piloted in South Africa, is one method to produce ettringite. In this process, aluminum hydroxide is the aluminum source. The Cost Effective Sulfate Removal (CESR) process is similar to SAVMIN, but uses a proprietary aluminum source instead of aluminum hydroxide. Outotec and Veolia also have their own versions of the process using their specialized process equipment. TWC patented a version of ettringite precipitation using metallic aluminum as the aluminum source for ettringite formation. The benefit of using aluminum metal is that no additional ions are added to the process. At high pH, the raw aluminum corrodes in water causing hydrogen gas generation as the water is chemically reduced. This reaction is shown below:

Jan 1, 2019