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By Anuradha Khetwal, Tala Tahernia

The estimation of TBM utilization rate can be problematic due to the uncertainty involved in the tunneling system reaction to various geology along the tunnel. Moreover, the impact of operational and management issues on TBM performance is unsettled. This includes the occurrence and duration of downtimes and the uniqueness of projects relative to the geology, machine type, backup system, site setup, crew experience, and operational restrictions imposed on the project by localities. The CSM2020 is a model based on discrete event simulation that predicts machine utilization for single or double shield TBM. This model was developed by the Earth Mechanics Institute (EMI) team, using the database of tunneling activities which was compiled based on field observation and measurements in pertinent projects. In the current study, CSM2020 was modified to simulate the workflow of slurry TBMs. The operating principle of slurry shield TBMs is different than open-mode TBMs. The model was verified by comparing results with a recently completed project in the United States. As a result, the model offers reliable utilization rate estimation in different types of TBM by implementing appropriate workflow.

Dec 1, 2022

By H. Maleki

The U.S. Bureau of Mines pioneered the use of borehole deformation gauges and overcoring techniques to measure in situ stress. These measurements provide input to structural mine design and support selection for specific geologic conditions. This paper presents recent stress measurements in a western U.S. coal mine where the orientation of the stress field remained relatively unchanged over distances of several kilometers. The horizontal stress magnitude increased with depth of cover and in relation to major geologic structures. Local variations in roof stress profiles were used to develop generic models relating stress arching to strata stiffness and the inelastic behavior of mine roof.

Jan 1, 1994

By James N. Brentz

This paper deals briefly with the problem of efficiently selecting the most cost effective haulage truck. Problems and factors are identified that effect productivity and operating cost. Despite the sophistication of computerized vehicle simulation programs, there is a wide disparity in accuracy and methodology, particularly in dealing with the various elements of cost.

Jan 1, 1984

By C. C. Harvey

As we move towards the 21st Century there are several factors that will influence the markets and processing requirements for industrial minerals. Traditional markets for many industrial minerals in the developed world are frequently stagnant or decreasing because of their maturity or due to environmental factors such as reclamation, recovery of byproducts, and recycling. Some industrial minerals are greatly affected by these factors, while others are either immune to or have adapted successfully to meet these challenges. In the developing countries of the world, there is rapid market growth and resource exploitation. The future of specific mineral commodities in several markets will be discussed.

Jan 1, 1997

By Thomas F. Stinson

Energy-producing states see severance taxes as attractive sources of increased revenues for otherwise tight budgets. Consumers in energy-poor states, however, protest that current rates are excessive and have moved to obtain a reduction. The US Supreme Court heard two cases questioning such taxes during its 1981 term, and Congress, in each of its last two sessions, has seriously considered measures placing a ceiling on severance tax rates. Although discussions usually focus on coal severance taxes levied by Montana and Wyoming, ramifications of changes in national policy are much larger, potentially affecting mineral taxes in all states. Severance taxes yield substantial revenues in some states, as illustrated in the accompanying table. In fiscal 1980, Texas collected more than $1.5 billion from such taxes, while Louisiana, Alaska, and Oklahoma collected $525 million, $507 million, and $436 million, respectively. Oil and natural gas production were the major items taxed. While the table shows only the 10 states with the largest severance tax collections, a total of 17 states had severance tax receipts exceeding $10 million in 1980. The enormous increases in severance tax revenue between 1970 and 1980 can be seen from the table by comparing columns A and B. For the 10 states shown, revenues increased from $650 million to $3.8 billion during that period, due to a combination of higher prices, increased production, and new or increased taxes. In most states, increases in prices and production were more evident than higher tax rates. Although the revenue increase is impressive, it understates the extent of changes occurring during the past decade. Since tax collections are shown for fiscal 1980, the full impact of the decontrol of domestic oil prices is not evident. Also, taxes on natural gas reflect controlled prices. When full de-control of natural gas occurs, significantly higher revenues can be expected in gas-producing states, even if tax rates, production, and world prices remain constant. These increases in severance tax revenues, coupled with further increases expected to accompany natural gas decontrol, have produced fears that a substantial transfer of income is taking place from residents of energy-poor states to those living in energy-rich areas. Others worry that increased severance tax revenues will be used to substitute for a substantial portion of state taxes that would have otherwise been collected from firms and individuals. The resulting improvements in tax climate, it is thought, may encourage firms and workers to migrate to energy-producing states. While these issues are often portrayed as pitting energy have-nots against the haves, such is not entirely the case. Much of the original impetus for limits on coal taxes came from Texas residents, the state collecting the most severance tax revenue. One way of gaining perspective on these concerns is by examining severance taxes per capita and as a percent of state tax collections (see columns C and D in the table). When this is done, Alaska, where 1980 taxes on oil and gas production totaled more than $1300 per capita (and 35% of all state tax collections), stands out as a special case. There, the state was able to eliminate some individual taxes, place revenues in a permanent trust fund, and consider offering a rebate of some previous income

Jan 4, 1982

By George L. Atwood

The Monsanto Company's Henry Mine is located 17 miles northeast of Soda Springs, in the southeast corner of Idaho. Ore being mined is phosphate rock which lies in the Permian Phosphoria formation. The ore is the raw material for Monsanto's three furnace elemental "P" plant near Soda Springs. The finished product from the furnaces is elemental phosphorus which is subsequently used in the manufacture of detergents, food preservatives, fire retardants and other consumer items. Mining is by open pit methods using 0-9 crawler tractors to rip and push-load rubber tired scrapers in stripping and mining operations. The equipment spread consists of six D-9G crawler tractors, four Caterpillar 6578 scrapers, eight Euclid S-24 scrapers, one Reich T750 drill and one Caterpillar No. 16 patrol plus various support equipment. Stripping is performed on a 12-month basis, two shifts per day. Mining is performed mainly in the summer months on a one shift basis. The hauling season begins May 15 and ends November 1 due to freezing weather and snow conditions. Annual production is 1,000,000 tons of phosphate rock and 2,500,000 to 3,000,000 yards of stripping. Stripping, mining and hauling is performed for Monsanto by Dravo-Soda Springs, a mining contractor. Dravo-Soda Springs owns, operates and maintains all equipment used in stripping, mining and hauling. The contractor is paid for stripping by the bank yard and for ore mined and hauled on a tonnage basis. The Monsanto elemental phosphorus plant began production in 1952 with ore being trucked to the plant from the Ballard Mine. Haulage was over public roads in 15, 24-ton semitrucks. A private haul road was constructed from the Ballard Mine to the Monsanto Plant in 1958 and 1959 to accommodate trucks with two twenty-yard trailers. This 11/ mile road was first used in the 1959 hauling season. In 1965, five new Kenworth tractors with two, 'forty yard trailers were introduced into the haulage system. These units carried 120 ton payloads and were used until

Jan 1, 1972

By T. Owen

Not since 1917 has a foreign company developed a standalone, grass roots gold mine in Russia. With. Russia's political changes of the late 1980s, development of mineral prospects once again beckons foreign investors. In 1990, Cyprus Amax began aggressively searching for such an opportunity. Early in 1997, production will commence at the Kubaka gold project located in the Russian Far East, near the Arctic Circle. The Kubaka project is a 1,750-tonne per day open-pit operation that will produce more than 300,000 ounces of gold per year. This paper discusses the challenges of locating such a prospect, doing business in Russia, developing supply lines, identifying work force capabilities, gaining government approvals, securing financing, arranging for gold sales and ultimately building a facility in this arctic region.

Jan 1, 1997

The future phosphate rock deposits in South Florida contain a significant fraction of dolomite. The high MgO content of the rock is undesirable in the production of phosphoric acid. Several flotation schemes have been attempted to separate dolomite from phosphate rock. Alternately, Selective Flocculation process has been suggested to separate dolomite from apatite. A high MgO content rock was simulated by a 30:10:60 synthetic mixture of apatite, dolomite and silica. Single mineral selectivity was observed in the mixed mineral systems apatite-silica and dolomite-silica with Polyacrylic acid (PM) and Poly(ethylene oxide) (PEO) flocculants respectively but not realized in apatite-dolomite system with PEO flocculant. Heteroflocculation, suspected to be the major reason for loss in selectivity, was minimized by addition of a Site Blocking Agent (lower molecular weight fraction of PEO). Process parameters such as size reduction schemes, flocculant/SBA dosage, and pH were investigated to achieve the desired separation. The selectivity obtained in binary mixed mineral tests was translated into the ternary mixed mineral system, viz. apatite-dolomite-silica. In this presentation surface chemical characterization of the samples and their flocculation behavior will be discussed.

Jan 1, 1994

By N. B. Aughenbaugh

Compacted clays are used as permeability barriers in many mineral engineering projects such as heap leaching, containment ponds, tailings disposal and earth dams. Source materials used for clay liners include a wide variety of sand, silt and clay admixtures that exhibit dramatically different engineering properties when densified. The permeability and plastic properties of fine-grained soils are reviewed with respect to the state of compaction as the water content varies. Be-cause they are weak in tension, compacted clays are susceptible to cracking when subjected to differential flexural movements. Designs of compacted clay liners must include an evaluation of their flexibility which is the ability of a fine-grain soil to bend plastically without cracking. This paper will also discuss the importance of flexibility with respect to soil types, compaction effort, failure mechanism and testing evaluation to the performance of clay liners in preventing seepage of pollutants from a containment site.

Jan 1, 1990

By Stephen Utter

This report summarizes the results of preliminary investigations concerning the influence of block caving mining upon adjacent mine openings and discusses possible methods for reducing critical rock pressures and damage to these openings. These investigations are one part of a general study of the rock mechanics of block caving by the Denver Mining Research Center of the Federal Bureau of Mines. The purpose of this part of the study Is to obtain an estimate of the stress concentrations around mine openings adjacent to block caving stopes for use in developing better designed openings and improving mining methods. When mine openings such as slusher drifts, grizzly drifts, and haulage drifts are damaged by rock pressures induced by block caving mining, the mining cost increases, mine production decreases, and ore recovery may be consider- ably lessened. Methods of mining that result in lower rock pressures and methods of design that enable mine openings to withstand these pressures are desirable. The development of these methods, in turn, requires a fuller understanding of the following: The stres concentrations around the mine openings and the changes in stress induced by adjacent mining; the physical properties, such as the compressive strength and modulus of elasticity of the rock surrounding the openings; and the support supplied by the concrete lining, timber sets, or other types of supports used in the openings.

Jan 1, 1962

By W. J. Kogelmann

Roadheaders, also called Boom Miners or Boom-type Tunneling Machines have been in North America since 1968, when first introduced by Willy Kogelmann, the founder of Alpine Equipment Corp. (?Alpine?). Roadheaders were invented in Europe in the late 1940s. Machines with in-line, axial cutter heads were developed in the former Soviet Union. The British Dosco DRCL is based on the Russian PK-3 roadheader. Roadheaders with transverse ?ripper? cutter heads were invented in Hungary (1). The Austrian-made Alpine Miners of VOEST-Alpine, purchased by Sandvik AB, are based on a 1965 Hungarian license. Roadheaders are widely used in the mining and tunneling industries because they can excavate drifts, entries and tunnels with cross sections of any shape and size, can handle mixed faces, work on steep grades, and negotiate tight curves and cross-cuts. A roadheader?s only major limitation is the strength and abrasiveness of rock and minerals to be excavated. This paper covers roadheader selection criteria, improvements in reliability, attachments for flexibility (Multi-Tool Miner), and automated support systems for increased cutting time for increased shift production.

Jan 1, 2008

By Stephen H. E. Phillips, Michael J. Beus

A pneumatic impact breaker is used to fragment the rock at the shaft bottom, replacing the drill and blast cycle. A backhoe-type mucker removes the broken rock. The operators are in protective cabs below the bottom work deck in the shaft. Preliminary testing has been accomplished at underground and surface test sites in Arizona. Seven, approximately 6.4 m deep by 7.3 m-diameter (21 ft by 24 ft) test holes, (a total of 45 m (148 ft)), were recently excavated in various rock types, including jointed and massive quartz monzonite and rhyolite. An average advance rate of .4 m/hr (1.24 ft/hr) has been achieved. This includes breaking and mucking the rock. Further data is being sought from an in-shaft demonstration.

Jan 1, 1981

By Cliff Holloway

The past year has been difficult for Canada's primary industries. The mining, oil and forestry industries have been hit by low prices and a reduced demand for natural resources. Foreign competition, militant environmentalists, the breakdown of the Asian and European economies and Canada's shrinking dollar have all put additional pressures on the commodity purchaser to buy smarter. It is easy to appreciate why operations and maintenance supervisors want the best performing product. It makes good sense. The challenge is to source that quality product while staying within the budget. The bottom line (price), however, often becomes the control- ling factor, usually at the expense of quality and performance. This is short-term thinking, often with expensive consequences.

Jan 1, 1999

By K. L. Purdy

Electron spectroscopy for chemical analysis (ESCA) was used to determine the-surface characteristics of products from operating Pb-Zn-Cu concentrators on the New Lead Belt of southeast Missouri and pure galena and sphalerite samples treated-with flotation reagents in concentrations similar to those used in the mills. The emphasis was on the action of surface modifiers such as Na2Cr207, starch, SO2, CuSO4 and NaCN in sphalerite flotation and in the galena-chalcopyrite separation. The objective of the investigation was to monitor the relative oxidation states of the mineral and reagent constituents and correlate these surface concentrations and oxidation states with flotation theory and practice. ESCA was able to follow the action of all the modifiers except NaCN. The existence of PbCrO4 on the surface of galena conditioned with Na2Cr207 was verified. The Pb in the bulk PbS-CuFeS2 scavenger concentrate was found to be significantly more oxidized than the Pb in the bulk PbS-CuFeS2 rougher concentrate. ESCA was found to be most useful for investigating the actions of modifiers rather than collectors due to the large amounts of sulfur and background carbon already present on the mineral surfaces. After calibration for the particular chemical system of interest, ESCA can yield semi-quantitative analyses of the oxidation states of many elements (except hydrogen, and helium) present in the outer 10 to 25 A of a sulfide mineral surface.

Jan 1, 1975

By Richard L. Bullock

INTRODUCTION TO COAL MINE PRACTICES To illustrate the trends and the proportions of the various methods used to mine coal underground, Fig. 1 is useful. However, of all the underground coal mining practices in the US, room-and-pillar mining still accounts for 96.5%. This percentage is divided as follows: conventional, machine cut-33.0%; conventional, hand cut -1.7% : and continuous mining-61 .8%. As was stated in Sec. 1, Chap. 7, the term "development" means different things to a coal miner and a metal miner. Though some of the ideas and concepts presented in the first two chapters of this section are valid for all types of mines, they apply particularly to mines using noncoal methods. In coal mines (and many other mines using coal mining systems) development refers to that phase of the mining cycle which advances several entries through the virgin seam, forming pillars by cross- cutting between the parallel entries. Because in the past, coal seams (as well as seams of potash, trona, oil shales, gilsonite, salt, and some uranium) have been much more uniform in their thickness, continuity, and quality, and because they often cover large areas, it has been possible to develop the room-and-pillar mine completely from a preplanned, systematic approach with a minimum of surface drilling information. As the better coal seams of the midwest and east are being depleted (or eliminated because of high sulfur), seams of poor quality and continuity will have to be mined. Also, seams that are not nearly so well known at greater depth will have to be taken as well as some of the steeply pitching and folded seams of the west. The American coal miner is only now feeling the need to do a much more complete job of prospecting the geology of the coal seams than he has ever done before. This is the only way that the risk of unknown rock conditions can be minimized. In many ways, surprises in the rock or coal seams are much more of a disaster to the coal miner developing a room-and- pillar mine than to his metal mining counterpart. Be- cause of the multiple entries, the complex set of the Federal Coal Mine Health and Safety regulations, and the totally dedicated design of coal mining equipment, coal mining systems do not have the flexibility to easily overcome changes in the seams mined or the rocks around them. Thus, if a wide parting of rock shows up unexpectedly in the middle of a coal seam entry being milled away by a continuous miner, it will either have to slowly "chew" through it, convert to a conventional mining system, or stop that particular entry. Likewise, if suddenly the coal disappears completely and in its place are the remains of an old creek bed, the "want" or "wash out" as it's called will usually have to be mined right along with the coal, by the same methods and with the same soft rock equipment, or the entry will have to be abandoned. For reasons such as these, coal seams today should be drilled from the surface just as thoroughly as the ore bodies in metal mines. Having once determined a more precise location of where the coal seams are located and which are suitable for mining, the engineer must still take a systematic approach to planning the mine as completely as possible. The initial series of entries must be planned to be driven either from the side hill portal or from the bottom of the shaft or slope. In either case, they should usually intersect the area close to the midpoint of the mass to be mined.

Jan 1, 1982

By C. Perea, O. Restrepo, C. Ihle, H. Estay

In this study, research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presented. Copper dissolution was conducted following a hydrometallurgical route, using monosodium glutamate in alkaline solutions. The effect of oxidizing agents such as hydrogen peroxide (H2O2) and potassium permanganate (KMnO4), and the efficiency of copper leaching with glutamate compared with glycine have been studied. Results, obtained at room temperature, showed 92% recovery of copper using 0.03 M hydrogen peroxide, 0.5 M monosodium glutamate at a pH of 9.44.

Mar 2, 2022

By S. K. Kawatra, J. A. Halt

"INTRODUCTION Iron ore beneficiation needs advances in areas such as process control, automation, burner and furnace designs, silica-free binders, and even alternative iron making routes. While some – like new binders – are only step-changes, all are tools that can help make the ironmaking industry more sustainable. This paper focuses on binders. Binders are added to iron ore fines before they are agglomerated. Binders are used to control the balling process and increase the mechanical quality (e.g. strength) of green-balls and pellets. Agglomeration usually follows thickening and filtration. Good-grade ores, which don't require upgrading, are wet ground to decrease particle size and increase specific surface area. Low-grade ores are often extensively upgraded through wet operations (flotation, dispersion and selective flocculation, magnetic separation, etc.). For both types of ores, thickening and filtration conclude the circuits so that moisture contents are lowered and the ores can be agglomerated. It's been known for a long time that thickening and filtration behaviors are influenced by zeta potential (Sandvik, 1979). Highly-negative zeta potential is good for dispersion while low zeta potential is good for filtration. So, the zeta potentials of iron ore particles are lowered with additions of acid or carbon dioxide, for example, to increase filtration rates and throughputs (Eisele et al., 2005). What happens to particles as their zeta potentials are lowered? Particles aggregate together, effectively forming larger particles. How stable then, are those aggregates during mixing and balling? Are they easily broken up during mixing (if mixers are even used)? Are they broken up during balling? Or, do the aggregates resist breakage so that the availability of ultra-fines, which are so beneficial for agglomeration (Stone, 1968), is decreased? For plants where high doses of bentonite are used as binder, the above questions may be of no concern. The bentonite adds the necessary amount of fines; however, even at those plants, the calcium and magnesium contents in the water affect bentonite's effectiveness (more magnesium and calcium means less effective bentonite). (Engesser, 2003) For plants where new silica-free organic binders are being developed and used, the above questions may need to be considered. The binder is only amongst the iron ore particles for a short period of time – until it burns away or thermally decomposes in the induration furnace – so the liberation, availability and distribution of fine particulates is very critical for the quality of balls and pellets. It was hypothesized that high zeta potential conditions would lead to good pellets, while low zeta potential conditions would lead to relatively bad pellets."

Jan 1, 2018

By R. G. Johnston

Minerals have many uses in paint systems. These roles include use as primary and extender pigments, sheen control, film durability enhancement, and rheology control. These and other uses of minerals in paints, and the effects of mineral quality variations on coatings performance are discussed. As coatings performance requirements become more demanding, tighter consistency of important mineral properties, such as particle size distribution and purity, is becoming increasingly vital. Future directions of mineral use to meet projected environmental restrictions and performance demands on coatings, including the use of advanced minerals technologies, are examined.

Jan 1, 1993

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By Jonathan G. Price

Silver-copper-lead deposlts in Precambrian, Permian, and Cretaceous red-bed sequences near Van Horn, Texas, have the following features In common: (1) mineralization controlled by steeply dipping fractures in sandstones, (2) lack of ore In overlying and interbedded limestones, (3) absence of igneous intrusions, (4) sulfide ores without typical hydrothermal gangue minerals, and (5) associated arsenic, molybdenum, zinc, and cadmium but not gold. Ore was probably deposited along fractures by reaction between low-temperature, oxidizing, metal-rich ground waters and sulfide-bearing waters or rocks. Detailed mapping and studies of fracture patterns indicate that mineralization occurred during Basin and Range extensional deformation, thereby postdating major Trans-Pecos igneous activity.

Jan 1, 1983