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By Jr. Wallace

This paper describes the importance of mine ventilation and air conditioning in the operation of a nuclear waste repository. It discusses the impact of ventilation on determining the number and size of shafts and access drifts to and within a repository horizon. The paper also describes the need to maintain separate ventilation systems for waste emplacement and construction operations. The requirement to have filtration capabilities for exhaust air from waste emplacement areas is discussed. Because radioactive high level waste will induce high temperatures in the emplacement drifts, the ability to cool an emplacement drift for re-entry requirements is important. The paper discusses strategies to cool an emplacement drift and the possibility of using continuous airflow to control temperatures in these drifts.

Jan 1, 1991

By J. R. R. Bowling, A. McFadden, M. Francoeur

The abstract discusses the increasing use of extensive duct-fan systems in underground hard-rock mine development. It highlights the challenges of designing these systems, particularly the risk of partial vacuum and the need for careful booster fan positioning. The paper explores factors influencing the design of these systems, including component limitations, operational wear margins, and power constraints. It also defines the concept of partial vacuum and its impact on ventilation ducts. The authors propose an algorithmic approach for specifying the location and blade pitch of in-line booster fans to prevent system failure.

Mar 17, 2022

By David A. Summers

In May 1975 the U. S. Bureau of Mines contracted with the University of Missouri-Rolla, Rock Mechanics and Explosives Research Center to develop a Hydrominer modification to a long-wall shearer unit, wherein the rotating pick-laced drums and connecting gear drives are replaced by a water jet cutting head.1 The concept of the water jet cutting head is based on using the high localized energy of the water jets to isolate a slice of coal by cutting a slot under, at the back of, and at the top of the web. The plow blade of the head then advances into the cut and wedges the pillar over onto the conveyor (Figure 1). There were several potential advantages foreseen for the system of which perhaps the most significant were the elimination of coal dust from the working area2 and the ability, with a variation in nozzle geometry, to cut webs of greater depth with a small increase in equipment horsepower. The University initially designed the head, based on experiments carried out in the laboratory, under an earlier Bureau of mines contract. The experiments showed that it was more advantageous to work at a pressure of 10,000 psi with an estimated flow rate of 50 gpm than go to the higher pressures and lower flow rates which have been advocated elsewhere.

Jan 1, 1977

By C. L. Karr, D. E. Goldberg

This paper considers optimization of the design and operation of an air-injected hydrocyclone (AIHC) via a genetic algorithm (CAI. The AIHC is a mineral separating device, developed by the U.S. Bureau of Mines, that combines the selectivity of flotation with the capacity and simplicity of hydrocyclones. GA's are search procedures based on the mechanics of natural genetics. Computer results demonstrate the ability of a GA to rapidly locate design and operating parameters that improve AIHC performance. A computer model of the GA-designed AIHC predicts improved recovery over that currently being obtained with an AIHC in operation at the U.S. Bureau of Mines Tuscaloosa Research Center.

Jan 1, 1990

By S. K. Sharma

The Bureau of Mines' Tuscaloosa Research Center is conducting research to develop a basic understanding of solid-liquid separation in order to improve the dewatering of fine particle slurries. In the present investigation capillary suction time (CST) of kaolin slurries was determined. The average specific resistance of the cake was also determined by fitting the CST data to the theoretical equations used in this paper. The experimental data were analyzed by a powerful computer-based method, chemometrics, that uses statistical techniques to remove error and to find the number of physically significant factors contributing to the data. Results showed that two significant factors explain the CST data.

Jan 1, 1991

By N. S. Tanious

This paper summarizes the results of an investigation into possibly the largest coal pillar failure in the USA. The newly opened drift mine is located in Southeastern Kentucky and worked an 11 feet thick coal seam, all other mines in the District worked seams 4-5 feet thick. The initial mine development consisted of 14 main entries (Fig. 1) which were driven in two sets of 7, under increasing depth of overburden. As the left seven entries came under deeper overburden the pillar ribs began sloughing which caused many of the concrete-block ventilation stoppings to crack. The mine management stopped the advance in the left seven and continued with the right seven entries. During the spring of the following year development resumed in the left seven, rib sloughage occurred again and this time severely cracked many stoppings and many were totally disintegrated from the excessive deformation. Within few weeks the sloughage was so heavy that many of these entries behind the active face were filled with piles of sloughed coal slabs. When the face reached a depth approximately 1150 feet, the sloughage became a slow, massive squeeze. The entry convergence (closure) reduced their height from 11 to 7-8 feet and the squeeze spread back to shallower depth covering an area roughly 300 pillars.

Jan 1, 1989

By R. J. Sweigard

One possible alternative for disposal of flue gas desulfurization (FGD) by-products is use as backfilling support material in highwall mine adits. The finite element method was used to analyze the variation of stresses and displacements within and around a highwall adit backfilled with FGD materials. The engineering properties of the rock material and the optimum mix proportioning of the FGD materials were obtained from laboratory tests. Finite element analyses show that, for the case in question, the roof displacement would decrease about 48 percent and the peak stress could be decreased about 58 percent. The study indicates that fairly weak FGD materials can eventually lead to stability of backfilled highwall adits.

Jan 1, 1996

By Rick Frechette, Greg Nelson

"The 2018 Elko Roundtable was held at the Red Lion in Elko, NV on March 15, 2018. The gracious host was once again Knight Piésold. Attendance was robust with representatives from more than 14 mining properties across Nevada representing nine corporations. Total attendance was at its highest in almost a decade. A high level of interest was also gauged by the number of companies with multiple attendees.The topic of water in mining was clearly a factor in creating the large show of interest. In terms of industry trends that are tracked annually, this topic had been absent from the list for more than 10 years (Deloitte, 2018) but was squarely planted there this year. And deservedly so. Three attending companies are signatories of the International Council on Mining and Metals (ICMM) which espouses a firm stance on water stewardship (ICMM, 2017).How’s the water?It is reported that water scarcity affects more than 40 percent of the world’s population (Deloitte, 2018). Consumption of water in the United States, based on the last detailed census, entails only 1.5 percent usage by the mining industry. The largest users are reportedly thermoelectric power and irrigation, combining for more than 75 percent of the U.S. consumption. During the prior census period, water usage at mines was up dramatically (USGS, 2014).Mine water source usage is primarily a mix of ground water and saline or fresh surface water resources. Over the previous period, saline sources experienced the greatest percentage in growth as a mine water source, nearly doubling in use. Nevada ranks second as a state nationally in mine water consumption. California is the leader, and Nevada is immediately followed by Utah and Alaska (USGS, 2014).Water rights in Nevada and the ongoing litigation at the state level, particularly over the Humboldt River basin, have elevated the concern over the supply of water and have raised the interest regarding the topic of water across the mining industry as well as within other industries.The Elko Roundtable meeting began with a safety share and introductions, and included each attendee mentioned a water problem or solution that he or she would like to discuss during the day. An interesting list of subtopics was developed from this round robin and yielded the following most common themes:• Mine pit dewatering during operation and pit wall stability.• Draindown from tailings dams and heap leach pads and dealing with this at closure.• Post closure pit lakes, pit lake water quality and associated water rights."

Dec 1, 2018

By S. K. Kawatra, J. E. D. McDonald, S. C. Roache

"The formation of geopolymers from mine tailings using cold-bonding processes is known to be possible. Numerous cold-bonding methods exist, but the hydrothermal processes involving high temperatures and pressures in the presence of steam have been found to be the most ideal. This paper presents the results of successful preliminary studies to apply hydrothermal bonding processes to mine tailings agglomerates. Particle-size analysis revealed the particle size of the tailings waste to be 80 percent passing at 35 µm. The compressive strengths of the tailings pellets were shown to increase with time in the curing vessel, closely approaching the 400 lbf of standard iron ore concentrate pellets. These strengths are sufficient to allow use of the tailings pellets as aggregate materials for asphalt and cement. Additional applications may be possible, including reprocessing to extract more valuable materials and usage as agglomerated road-bed materials, backfills for building foundations, and replacements for sand and lime in cement.IntroductionMine tailings are a waste byproduct of ore concentration and are available in large quantities across the world. Despite their abundance, they have received little attention or consideration for beneficial use. One reason is that the chemical nature of the material is not well known. Another factor that has hindered direct usage is the fine particle size. This raises the questions: what is the composition of the tailings, and how can such fine solids be beneficially used? Because the mining industry produces concentrates, the tailings may be treated as concentrates and processed in the same fashion, but it would be inefficient to consider full sintering or induration conditions for materials that have little ore content. To achieve sustainable operation, the development of technologies to use these tailings is necessary. Mine tailings should not be considered waste, and an “out of sight, out of mind” mentality does not represent a sustainable solution for the future.One iron ore mine in Michigan is estimated to have accumulated more than 400 million metric tons of tailings during its last 30 years of operation, with an additional 180 million metric tons accumulated before the ore body is depleted. These mine tailings currently have no practical use, largely due to a scarcity of knowledge of their true physiochemical nature. It is thought that lack of quality control of the waste material prevents its use, but variability in the unprocessed ore prevents a consistent waste stream composition. The fact that the tailings are available in such great quantities makes them an extremely attractive resource. However, developing a sustainable, low-cost means of repurposing the mine tailings waste as a construction material may only be completed once the tailings are physically and chemically understood. Due to the high silica content of the material studied, cold bonding was determined to be the most viable method for processing the tailings into a usable product."

Jan 1, 2016

By Y. C. Guan

The cementation of gold on to copper and zinc in ammoniacal solutions has been studied using rotating disc electrodes. The cathodic reduction of aurous ammine was studied on a gold rotating disc electrode and the anodic dissolution of copper and zinc was studied in the absence of aurous ammine. The cementation rate was found to be a first order with respect to the concentration of aurous ammine and to be proportional to the square root of the disc rotating speed. Based on the results obtained, it was concluded that the cementation reaction was controlled by mass transfer of aurous ammine to the reaction surface under the experimental conditions.

Jan 1, 1995

By P. B. Altringer

The Bureau of Mines, U.S. Department of the Interior, is investigating biodegradation of cyanide as a means of decommissioning heap leach operations. Biological oxidation decreased weak acid dissociable (WAD) cyanide in process solutions1from 50 to 170 ppm down to 0.1 ppm. The tests were conducted both in trickling column reactors, using quartz as the growth surface, and in upflow columns, using activated carbon as the growth surface. In addition, exploratory tests indicated that bacteria will destroy residual cyanide in leached ore. A flowsheet has been proposed for closure of heap leach operations in which the metals processing portion of the plant, possibly the carbon adsorption columns, or a collection pond is used as a bioreactor. The cyanide in the process solution is destroyed in the bioreactor and the treated water is used to rinse residual cyanide from the spent heaps. The water is recycled until the effluent WAD cyanide concentration meets discharge standards.

Jan 1, 1992

By R. Y. Wan

Newmont Gold Company has advantageously used the capabilities of mineral oxidizing bacteria to develop a process for pretreatment of low grade sulfidic and carbonaceous-sulfidic refractory gold ores. The biooxidation process results in the oxidation of the sulfidic minerals with increased exposure of gold for subsequent gold recovery. The biooxidized carbonaceous-sulfidic ores cannot be heap leached with cyanide because of the "preg-robbing" characteristics of the carbonaceous matters in the ores. An alternative heap leach process using ammonium thiosulfate was developed to extract gold from the "preg-robbing" biooxidized ores. The ammonium thiosulfate leach process has been successfully practiced both in laboratory and pilot plant testing. Satisfactory test results encourage the continuation of process development.

Jan 1, 1996

By Eva K. Fernandez, Paul Y. Louie, Derek S. Adams, Renée L. Fippin

The Folsom Area Stormwater Improvement Project is part of SFPUC’s flood resilience efforts under the Sewer System Improvement Program. This 4,000-foot-long, 12-footinside- diameter tunnel will help reduce the risk of flooding in San Francisco’s low-lying Inner Mission neighborhood. The project is in a high seismic hazard zone and extends through a complex geologic corridor that includes full-face soft, compressible Bay Mud, Colma Sands, and full-face rock with several stretches of mixed-face conditions. Additional challenges include removal of 99 piles beneath an existing box sewer, tunneling under commuter rail tracks, and an underground tie-in. This paper examines these challenges and how they are being addressed.

Jun 13, 2023

By Paul Shimizu

BHP Robinson contracted Minnovex Technologies to implement a Comdale Expert System at their greenfields operation in Ely, Nevada. The expert system has resulted in a significant increase in tonnage. Other benefits have also been realised, including a reduction in operation upsets (having a positive effect on downstream processes, i.e. flotation) and reduced production variances between crews. The expert system is written in a unique manner using trend based logic with minimal hard limits. The result is a robust system that requires minimal operator supervision while producing very high results. The development, success and acceptance of the system can be attributed to the strong team that was assembled for this project. The team not only consisted of BHP Metallurgists and Minnovex but most importantly included operations.

Jan 1, 1998

By B. Hornsby

At the Mount Isa mine, Mount Isa, Qld., Australia, sublevel open-stope mining is used for copper ore while both sublevel open-stope and cut-and-fill methods are used for the silver-lead-zinc ores. Production in 1979¬80 was 4 730 000 t (5,200,000 st) copper ore and 2 590 000 t (2,850,000 st) of lead ore. The deepest mine level currently is 960 m below the surface. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size, Shape, and Dip The mine is located in the valley of the Leichhardt River in Lower Proterozoic sediments of the Mount Isa group. The regional strike of the sediments is north¬south and they have a persistent westerly dip of about 1.1 rad (65°). In the mine area, the Mount Isa group comprises a sequence of alternating bands of dolomitic shales and siltstones some 3.2 km (2 miles) in width. It is bounded on the east by greenstones and quartzose sediments of the Eastern Creek volcanics, and on the west by the Mount Isa fault, west of which occur schists and other metamorphic rocks. The ore bodies as currently known at Mount Isa are restricted to the Urquhart shale, a formation of thinly bedded pyritic, dolomitic, and volcanic shales some 1070 m (3500 ft) thick. Towards the top of the Mount Isa group sediments, copper and silver-lead-zinc ore bod¬ies occur as contiguous but discrete entities and are mined and treated separately (see Figs. I and 2). Argentiferous galena, sphalerite, pyrite, and minor associated sulfides occur in distinct concordant bands throughout the Urquhart shales. Wherever these bands are grouped together in sufficient density they constitute silver-lead-zinc ore bodies with widths varying up to 36.6 m (120 ft). Other mineralized bands are common in intervening beds. Individual ore bodies persist for many hundreds of meters concordant with the strike and dip of the enclosing shales. Intersections of these beds with fold axes provide local zones of enrichment but otherwise the mineral content of the ore bodies varies only slightly throughout the extent of the dip and strike. Chalcopyrite is the only important primary copper mineral. It occurs in association with pyrite and pyrrhotite as disseminated flocks and as vein fillings throughout irregularly shaped zones of folded, brecciated, and re¬crystallized Urquhart shale. These zones, which are lo¬cally termed "silica-dolomite" bodies, are broadly transgressive to the shale bedding and confine all significant copper mineralization to the virtual exclusion of silver¬lead-zinc mineralization. In some areas, the downward percolation of acidic water through faults and shears has caused extensive leaching of the coarse-grained carbon¬ates to depths in excess of 610 m (2000 ft), but most of the silica-dolomite remains unleached and the ground is competent. The majority of lead ore being mined is north of the main shaft pillar (R62, U62) area. The major lead¬producing areas for many years have been the Black Star ore bodies (2 and 5 ore bodies) and the Racecourse ore

Jan 1, 1982

By Walter C. Jr. Sherman

6.1-SOIL MECHANICS WALTER C. SHERMAN, JR. 6.1.1-DEFINITION Soil mechanics is concerned with the behavior of soils in relation to the design, construction and performance of engineering works. In this context, soils include all uncemented materials, such as, gravels, sands, silts and clays, either naturally or artificially deposited, and, under certain conditions, weakly cemented, badly broken or weathered rocks. Many types of mine wastes have physical properties similar to those of soils and thus are amenable to analysis by the principles of soil mechanics. The principles of soil mechanics are used to solve such problems as the stability of various types of structures with respect to failure of the supporting soils, determination of soil pressures and deformations in the design of foundations and retaining structures, analyses of seepage and under seepage, and stability with respect to sliding of excavated and natural slopes and embankments. 6.1.2--SOIL PROPERTIES Soils are classified on the basis of index properties, such as, particle-size distribution and plasticity characteristics. The Unified Soil Classification System1 used to classify soils for engineering purposes is shown in Table 6-1. Other physical properties important from an engineering standpoint include natural water content, density, permeability, shear strength and compressibility. Physical properties are evaluated on the basis of carefully conducted laboratory tests. Procedures for laboratory testing are presented by Lambe. 2 Soils, either of natural or artificial deposition, are complex three-phase materials consisting of solids, water and gas (usually air or water vapor). One of the most important principles in soil mechanics is based on the concept of effective stress in the soil-water system. A stress, a, applied to a saturated soil is taken partly by the soil particles (effective stress, a'), and partly by the water in the voids (neutral stress or pore water pressure, u,) so that a' = a - u,. Only the effective stress affects the mobilization of frictional resistance between soil particles. In partially saturated soils, the pore-water pressure is negative due to capillary effects. The effective stress relation remains valid for small negative pore pressures, but anomolies arise if the soil is significantly unsaturated. In this case, the pore pressure is commonly assumed as equal to the pore air pressure, u,, so that [ u' = u - u..] 6.1.3--SOIL EXPLORATIONS Soil explorations are carried out by borings or test pits. Hvorslev3 has reviewed procedures and boring requirements, such as, type, depth and spacing employed. In general, soil strata are logged and representative exploratory samples are recovered for classification purposes and for determining the subsurface soil profile, which is constructed utilizing also knowledge of the geology of a site. Undisturbed samples are recovered if the properties of the undisturbed soil are required, as generally is the case. The undisturbed soil sampler consists of a thin-wall tube

Jan 1, 1973

By L. Sandbak

The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestones, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods. TRJV has been working to optimize ground support and mechanize top cut drift sizes and eliminate operating hazards associated with jackleg drilling. Safety Factor analysis based on bolt strengths has allowed us to pursue larger sized top cut drifts and to evaluate bolt length sizes and spacing. Switching from jackleg sized drifts of 10?W x 10?H to a mechanized 12?H x12?W top cut drift design has the potential to decrease overbreak, provide more uniform drift design sizes and bolt patterns, and increase ore production by at least 38%.

Feb 23, 2014

By J. Ye

A comprehensive flotation study has been carried out on a Chinese fluorspar ore using the packed flotation column developed at Michigan Technological University. The results are compared with that of a conventional mechanical flotation method on the same feedstocks. Key factors controlling flotation performance of both methods are evaluated based upon a simple statistic design. The flotation concentrate produced in one stage of the packed column has 4-S% higher recovery and much lower silica impurity content than that produced by up to six stages when a conventional mechanical cell is used. The results also show that the packed column flotation process is particularly suitable for recovery of finer fluorspar particles.

Jan 1, 1992

By R. P. Stahura

In many ways, conveyors are the lifeline of mining and processing operations. Like arteries in the human body, they continuously supply materials to and carry finished products and waste away from vital on-going operations. And like arteries, when the conveyors are running with less than maximum efficiency and productivity, it spells serious trouble for the operation's overall health. Inefficient conveyors suffer carryback, leading to the build-up of materials on idlers and other expensive components. They spill and leak material at loading zones and conveyor transfer points, causing accumulations that can damage the belt, wear moving components, and increase both clean-up labor and maintenance expense. They wander or mistrack, spilling material and endangering personnel and conveyor components including the belt itself. And through these inefficiencies, they multiply the operation's hidden costs. These added expenses are created in lost production, increased downtime for service and maintenance, and the cost of the replacement of prematurely worn equipment. In addition, the attitude that inefficiency is "good enough" is recognized elsewhere in the organization; as a result, other departments relax or operate at less than peak performance. Quality goes down and with it employee morale.

Jan 1, 1992

By A. A. Terchick

In 1970 U. S. Steel acquired the physical assets of mine, mine property, and preparation plant of the Crystal Block Coal Company near Thacker, Mingo County, West Virginia. The facility, identified as U. S. Steel Mine No. 20, is administered and operated as a production unit of U. S. Steel Gary District, Gary, West Virginia. Mining operations of the No. 20 mine are conducted in the high-volatile Alma seam. The preparation plant, which originally had a capacity of about 150 tons per hour (tph) of raw-coal feed, had process circuitry consisting of a Daniels heavy-media vessel for cleaning the plus-1/4-inch raw coal, a McNally-Pittsburg feldspar jig for cleaning the 1/4 inch by 28 mesh, and Daniels flotation cells for treating the 28 mesh by 0. No water-classification system existed. Refuse tailings from the plant were pumped to several surface lagoons which were decanted to the stream. The settled solids were removed and trucked to the coarse-refuse disposal area. Water make-up requirements were supplied by a small mine-water surface reservoir and augmented with stream water. Expansion of production from the property required an increase in preparation-plant raw-coal-feed rate capacity from

Jan 1, 1974