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By Christopher Newman, Robert Dupuy, David Newman

"The development of a multiple level underground mine is a complex task in which geology, engineering, ground control, and unit operations are integrated into a single mine design. The components are inter-dependent and must function cohesively to ensure a profitable underground mining operation. To optimize reserve recovery, mine planning should begin from the lowest level and progress up. This limits any misjudgments or oversights of a given level affecting the underlying levels and ensures the ability to maximize recovery from each level.Mine planning should start with the exploration and characterization of the geologic setting. Once the reserve geology and quality is well understood, then mine planning can begin with respect to the following:,Orientation of mine works with respect to horizontal stress,,Access to the reserve,,Determination of opening widths,,Selection of back, floor horizons and pillar centers,,Selection of development and secondary mining heights,,Appropriate interburden thicknesses, and,Examine the stability of the multiple level mine through numer¬ical modeling.The multiple level mine design process and decisions are presented through a case history example. The theme is that there is one opportunity to “get it right” as well as many chances to overlook a small aspect within the design that will plague the mine throughout all levels and through the entirety of its operating life.INTRODUCTIONAs surface quarries reach their economic stripping limit and encroach on mineral and/or reserve boundaries, they approach the end of surface mineable reserves. Furthermore, modern urban sprawl has placed previously remote surface quarries within suburban development and neighborhoods, leading to significant increases in noise, dust, and vibration grievances by the community and regulators (Newman, 2017). Many mining operations have begun year-round production of underground reserves to meet growing market demands. This does not permit the typical sequence of stripping overburden in the winter to provide limestone to mine during the construction season. Underground stone mining operations in the United States commonly utilize a room-and-pillar mine layout with drill-and-blast production methodology for the development of the reserve. Within the Midwest and Eastern regions, thick and flat-lying limestone formations lend themselves to the utilization of multiple level mining layouts. While a multiple level mine plan will increase the overall recovery of the reserve, greater overburden depths, multiple level geometry, and the presence of discontinuities all require an emphasis on ground control for the planning and development of a safe and productive multiple level underground stone operation."

Jan 1, 2019

By Patricia Pride, Kurt Bettger, Jack Raymer

"INTRODUCTION The Jefferson Barracks Tunnel is in the final stages of design and is expected to go out to bid in the summer of 2016. The project is located in south St. Louis County along the west bank of the Mississippi River, about 13 km downstream of the St. Louis Gateway Arch. The project consists of a deep sanitary sewer tunnel, a deep pump station and several intakes. The intakes will divert sanitary flows into the tunnel and the tunnel will convey the flows by gravity to the Lemay No. 3 Pump Station, which will pump them up into the Lemay Waste Water Treatment Plant. The tunnel is about 5.4 km long and will be lined with 84-inch (2.1 m) fiberglass pipe. It drops at a gradient of 0.1 percent from south to north and will be bored through strong limestone using a hard-rock tunnel boring machine (TBM). The diameter of the TBM is anticipated to be about 3.4 m. The Owner’s original concept was for a relatively shallow tunnel so as to minimize construction and pumping costs. The preferred alignment ran close to the river, next to the existing force main, which was to be abandoned. Keeping the tunnel close to the force main would reduce the amount of shallow sewer work needed to connect the existing feeder sewers to the new tunnel. Several geotechnical investigations were performed, with shallowly focused geophysics and the borings all going exactly down the conceptual tunnel depth. Limestone bluffs run along the Missouri side of the river. These bluffs are pockmarked by sinkholes and riddled with karst. Large, well-known caves occur both north and south of the alignment. Karst features, including deep crevices and possible caves, were found in those early geotechnical investigations. Many of these features extended well below the level of the Mississippi River and would have been encountered by the tunnel. If a large crevice or cave were encountered, then the inflow of mud and water into the tunnel could have been large and possibly uncontrollable. Something had to be done to mitigate this situation. Pre-excavation grouting was considered, but the program would have been huge and extremely expensive. Using a closed-face TBM with bolted and gasketed lining was also considered, but that too was both risky and extremely expensive. The Owner could have abandoned the tunnel altogether and built a new force main, but that would have brought a whole new set of problems and was undesirable to the Owner. The last option was to move the tunnel away from the karst."

Jan 1, 2016

By William E. Robinson

Our earthly treasures are being quickly depleted. We have experienced what can happen in an energy crisis. You have read and heard all kinds of stories as to what caused this crisis. On the surface it would seem that all of a sudden a situation becomes a crisis whether it be fuel, potatoes, beef or whatever. Well, of course, they don't just happen. There is always a little fore-warning here, an indicator there. Someone recognizes a sign of potential trouble but is ridiculed when he forecasts it. We are running out of sand: Producers of aggregates who can say today ... "That couldn't happen to me", can well be awakened tomorrow to the cold fact of reality. It could come from any number of directions. Depletion is mostly foreseeable but zoning isn't. Legislation can also be sudden death to availibility. With the ever growing population moving into the rural countryside, available deposits are being sold either to developers or being zoned for restricted use. The fact that a gravel pit or quarry is located on a particular plot has not fazed some of the local planning boards when they decided to place the adjoining property in a residential Zone A. Proponents of zoning preach that such use is necessary to insure that the land will be put to its best use. Planning boards establish the best places for schools, homes, shopping areas, factories, etc., so that the individuals or groups are in harmony with each other. This is usually done to date without thought or consideration to the geological importance or potential of the area. Today over half of the United States is living under some form of land use restriction. Little consideration has been given to what lies under the ground to be zoned. Fortunately, the states are slowly getting around to geological surveying. I feel that it is about time that state and federal authorities institute governmental restrictions to prohibit or control local zoning ordinances which would deplete or deny an area of its natural resources. While I could continue for the balance of my time just on this facet of our industry's problems, my point is: How sure are you of your next load of sand? I could be well laughed at by some of you for saying that there is an alarmingly rapid disappearance of "nearby" sand and gravel reserves in many areas of the country. A questionable statement, except to those producers where depletion has already taken place.

Jan 1, 1974

By Ian Hutchison, Ted Sluder, Jack Caldwell, Don Moore

Introduction The Cannon mine at Wenatchee, WA has recently been brought into operation to recover gold from the sandstones of the Swauk formation. The mine is a joint venture between Asamera Minerals (US) Inc. and Breakwater Resources. A tailings impoundment was constructed to impound 2.7 to 3.6 Mt (3 to 4 million st) of tailings at 1.8 kt/a (2000 stpd) over about five years. This paper describes the design and construction of the impoundment. In particular, it describes the 100 m (300 ft) high earthfill embankment that is the main feature of the facility. Project environment The project is located on the outskirts of Wenatchee, a town of about 40,000 people. The town is situated on the flat alluvial terraces beside the Columbia River. The Cascade Mountains rise from the terraces in a series of ridges and valleys. The mine is at the foot of the Cascades. The tailings impoundment is in one of the steep valleys. The climate is mild and dry (Table 1). Site selection Twelve alternative sites within a 16-km (10-mile) radius of the mine were examined. Decision making theory was used to select the most suitable site. Advantages of the chosen site include its proximity to the mine and its low visibility from points of common public access. Also, the area was already heavily impacted by an existing silica quarry. The major disadvantage of the site is the need to pump tailings over a distance of 1.5 km (1 mile) and against a static head of 200 m (655 ft). Also, it is located in a gulch just upstream from the town of Wenatchee. Site geology The impoundment is generally underlain by interbedded sandstones and siltstones. The siltstones are often shattered. The sandstones are often friable. Both rock types are extensively jointed. Some isolated faulting of the sediments occurred before the area was covered with basalt flows. About 10,000 years ago, at the end of the ice age, the basalts were covered by 3 to 10 m (10 to 33 ft) of wind blown loess - a fine sandy clay and silt. River deposits filled the base of the valley to depths between 5 and 25 m (16 and 82 ft). Under the main part of the embankment, these materials were removed to expose bedrock. Ground water flow is generally through the more permeable layers. The permanent water table is about 5 m (16 ft) beneath the ground surface. Project and impoundment layout Figure 1 shows the layout of the mine, the mill, and the tailings impoundment. The tailings deliv-

Jan 8, 1986

By F. N. Earll

4.1 – DEFINITIONS 4.1.1-MINERALS, ROCKS, ORES AND NONMETALLIC MINERALS F. N. EARLL A mineral is a naturally occurring inorganic element or compound. Most minerals are distinctly crystalline in habit, and many commonly occur in well-formed crystals or crystalline aggregates, but a few species are characteristically amorphous or noncrystalline. Nearly 2,000 mineral species are now recognized but, perhaps fortun¬ately, a rather large proportion are rarely encountered. Even so, the application of modern mineral-detection and identification techniques reveals the presence of surprising numbers of mineral species, even in deposits of outwardly simple mineralogy. A rock is an aggregate of grains or crystals of one or more minerals. Some rocks are essentially monomineralic. Thus, limestone consists largely of the mineral calcite, and many sandstones are dominantly quartz. Most rock varieties, however, contain a number of mineral species, and their classification or identification depends upon the minerals present, their relative abundance, and such factors as rock tex¬ture and origin. Ore is defined as an accumulation or deposit of one or more minerals that can be exploited at a profit. The profit criterion commonly is taken somewhat liberally, however, for, although always present, the specific mineral content that constitutes a viable product is transitory. The term ore, usually, but no longer consistently, is restricted to the description of mineral deposits that are of value for their metal content. Nonmetallic deposits, although similar to metallic ores in many respects, generally are valued for the minerals or compounds present, as with rock salt (halite), rather than for individual contained elements, though such minerals as elemental sulfur are of much value. 4.1.2-ROCK TYPES F. N. EARLL Rocks arc grouped tinder three broad headings: (1) igneous rocks formed by the crystallization of magma; (2) sedimentary rocks formed by surface processes of weathering and deposition; and (3) metamorphic rocks, which may have been derived from either of the foregoing, but have undergone important physical and/or chemical changes through the application of heat or pressure, or both. The three groups can he further subdivided for convenient reference. Thus, igneous rocks are described as being abyssal or plutonic if formed at great depth, hypabyssal if formed at intermediate depth, and extrusive or effusive if formed at or on the earth's surface. The sedimentary rock group is similarly subdivided into clastic sediments and chemical precipitates. The clastic sediments form by deposition of preexisting minerals that were released from their place of origin by weathering and were transported to their point of deposition as discrete grains

Jan 1, 1973

By Lawrence M. Brennan

Early in 1971 the Peabody Design and Preparation group began engineering on a preparation plant which was to process eight mil- lion tons per year of raw coal. For the first five or six years this product was to be furnished 50% from surface mining operations and roughly 50% from underground operations. By early 1980, 1008 of the production was to come from underground mines. Because of the large annual commitment from Randolph Preparation Plant, it was essential that the plant operate with minimum down-time. As usual, capital costs were to be kept at a minimum. Before we discuss the details of design, it would be best to discuss the overall picture. Underground production to be pro- cessed through Randolph Preparation Plant was to be delivered by means of one mile overland conveyor from Baldwin #1 Underground Mine to the plant. Surface Mine production was to be delivered by means of 100-ton haulage units dumping in a 1,000-ton capacity hopper. Because of the changing production rates in both the underground and surface mines as well as the great difference in size consist, it was decided that it would be necessary to divorce the plant as much as possible from production. For this reason, twin 6,500-ton raw coal silos were constructed to separate the two coals as well as allow blending. The preparation plant itself, was to be designed to Operate two shifts per day, five days per week, at an average rate Of 2,200 tons per hour with a maximum rate of 2600 to 2800 tons per hour. Coal was to be delivered to our customers by means of rail haulage at both unit train rates and plant process rates. The surface mined coal, after discharging into the 1,000-ton R.O.M. hopper, is fed by means of two 72" wide reciprocating feeders onto a 72" wide steel cable belt. The steel cabled conveyor discharges the R.O.M. coal onto a fixed grizzly, scalping out a percent of the 6 x 0 coal. The balance is fed to a 12' x 27' Rotary Breaker. The material passing through 6" round hole screens is added to the 6" x 0" from the scalping screen. The 6" x 0" is conveyed to the top of one of the 6500 ton silos designated for surface coal. Material that is not broken to pass the 6" breaker screen is discharged to a bin and disposed of with plant refuse.

Jan 1, 1976

By Kevin Bell

The TRAC™ Program was developed to provide our clients with a mechanism that allows them to better manage site remedia­tion and closure costs. This program provides a fixed-price contract for site remediation and case closure and is well suited for large pro­jects with multiple PRPs, such as Superfund sites. Because Kvaerner is a large engineering/construction firm and not a consult­ing firm, we can offer this type of contracting mechanism that envi­ronmental consulting firms are hesitant or unable to provide. With TRAC™, Kvaerner assumes financial and technical responsibilities for carrying a site through the closure process for a fixed price. Liabilities carried on our client's balance sheet for site closure can be removed when they sign up forTRAC™. In many instances, a profit can be realized as the liability on the balance sheet may exceed our TRAC™ fixed-price cost to close the site. Bonds and other sureties securing the site can be released and set­tlement with other involved parties can be quickly reached. For a project to be considered for this program, it typically meets the following criteria: 1) The project site should be physically separated from other contaminated sites 2) A reasonable quantity of site investigation data must be avail­able including site-usage history with or without a projected fea­sibility study(ies) and/or remediation design 3) Access to perform all necessary work must be available. After a review of all site data, K vaerner develops a "risk menu" to manage financial risks. In this "menu", each compo­nent of the project is assigned a level of probability that the costs will occur. Then the base cost of each activity is "weighted" by multiplying the potential cost growth by the probability. This analysis assures that the financial risks are appropriately defined, weighted, and mitigated and a realistic fixed price is developed. Upon acceptance of our proposal and conclusion of contract negotiations, Kvaerner takes over future responsibility for clos­ing your site. This allows the client to: 4) Release reserves obligated on financial statements for the site (and potentially realize a profit if the TRAC™ fixed-price cost is less than our client's booked obligation) 5) Finalize cost settlement with other responsible parties, insur­ers, etc. 6) Redirect resources involved in the environmental manage­ment of the site 7) Cap legal and administrative costs In addition to performing the site cleanup and closure work, at our client's request we are able to: 8) conclude lease obligations for property 9) dispose of equipment and buildings

Jan 1, 1998

By D. M. Milne, H. H. Kanduth

INTRODUCTION The past few years has seen an increased interest in the determination of statistically valid properties of a rock mass. The increased use of computer modelling for the study of rock excavation behaviour has created a need for upper and lower statistical bounds for the properties of a rock mass being modelled. Obviously, to determine the statistical properties of a large volume of rock, many samples must be tested - an expensive proposition when using conventional testing facilities and procedures. As a result of high costs per sample, sufficient tests for statistically valid results are rarely done. In an effort to reduce both sample preparation and test facility costs, an instrument called the Bemek Advanced Rock Tester (BRT) was developed in Sweden. With a total weight of approx. 35 kg, the BRT is portable and sells at a small fraction of the cost of a conventional testing machine. It is comprised of a small 65 KN loading frame with attachments for a variety of tests (see Table 1) , a hand operated hydraulic pump, an electronic balancing unit and a programmable microprocessor. The microprocessor is capable of storing data, performing arithmetic operation on, and printing signals from, a transducer and two strain gauges. A detailed description of the apparatus is given by G. Swan et al. (1). The proposed test strategy involves first a 3-point flexure test on a notched core specimen, followed by a 4-point flexure test on the separated specimen halves. Finally, point load and Brazilian tests can be carried out on the quarter parts of the original specimen. Thus specimen preparation is kept to a minimum. These and other perceived advantages have prompted the purchase of this machine and an evaluation of its suitability to provide data on mechanical properties of intact rock for numerical modelling and rock mechanics design at Noranda's underground mines. Details of its performance evaluation and experiences with the unit are discussed in the following sections. [ ] INITIAL OPERATING EXPERIENCE During the commissioning stage the BRT had, or developed, a series of problems, some of which seriously affected its operation. Below are some examples. Poor documentation was the most serious problem encountered. Confusing instructions for the 4-point bend test installation and its microprocessor programing, as well as poor and ambiguous information on the calculation of gauge factors, are some of the difficulties which had to be overcome. Meehan~cal problems occurred, including failure of the hydraulic pump, as well as electronic difficulties with the microprocessor. Other problems with the printer, requiring its replaceqent, were fortunately covered under warranty.

Jan 1, 1986

By George J. Allen, Laura A. Allen

Introduction This section of the text presents a general review of the different types of concentrate marketing contracts. Too often the marketing strategy is ignored in the design phase of the project and the producer is left to the mercy of the buyer. Many items such as concentrate grade, impurity levels and moisture content of the concentrate my enhance, or severely restrict the producers ability to make a profit it. Close attention should be paid to the design of the concentrator which can improve the quality of the concentrates, thus the ability to increase the rider of potential buyers can be enhanced. Difficult at best, is the position of the miner who only has one outlet available for its production. Obviously, the trade offs must be evaluated. For example, concentrate grade vs recovery and grind/filtering capacity vs moisture of the concentrate all must be weighted against freight cost to a potential buyer. In addition, the above considerations must be weighed against the capital cost to the miner. This chapter is intended to highlight important articles that are included in short and long term agreements and to give a new miner/producer some insight into hat my or my not add value to the product. Unless the miner sells the product directly to a consumer such as a gold, or silver producer, or to a large enough operation that has a totally intergrated system to make a finished product, most miners are forced to sell to buyers who ultimately will refine and market the product. Types of Contract Agreements There are many types of contract agreements just as there are colors in the rainbow, however, most contracts fall into three basic categories. (1) Smelter Schedules: Designed for the small producer, the odd lot of concentrate, smelter flux and precious metal ore. Albeit custom smelters are becoming fever by the day, because of pollution control requirements and financial difficulties, most remaining custom smelters have a smelter schedule. A smelter schedule is a posted list of charges and conditions that the smelter will buy material from a seller. Smelter schedules exist for copper, lead, zinc, silver and gold (Handbook for Small Mining Enterprises, Montana Bureau of Mines). (2) Short Term Custom Contracts: Large mine producers frequently use Short Term Contracts where the seller has the buyer frame a contract that is tailored to the sellers’ production. The short term contract my be as long as one year. A spot sale qualifes as a

Jan 1, 1986

By Dan Urich

This paper covers the construction and operation of the Grate-Kiln system at the Humboldt Mine. The mine concentrator and pellet plant are located approximately 14 miles West of Ishpeming, Michigan, on the Marquette iron Range. Production of pellets began in mid-July, 1960.

Jan 1, 1962

By W. J. Maloney, H. E. Tuneblom, A. J. Smith

The development of a large regional water supply in Southern West Virginia faced several hurdles. This paper deals with the design and construction of the intake shaft where a combination of cutting edge mechanical excavation technologies were utilized to produce a world class project.

Jan 1, 1999

By E. P. Chen

This investigation involves the development of a two-dimensional continuum model for the description of jointed media. Specific application of the model developed here is for the potential geological disposal of radioactive waste in the layered sequence of fractured volcanic tuffs under Yucca Mountain, Nevada. This is currently being considered by the Nevada Nuclear Waste Storage Investigations Project, administered by the Nevada Operations Office of the U. S. Department of Energy. The work is a direct extension of the previous constitutive model by Thomas (1982) based on the work of Morland (1974). The main feature of Thomas's model includes two parts: a continuum approximation based on average discontinuous displacements across jointing planes within a representative elementary volume, and a material constitutive description based on linear elastic matrix material behavior and nonlinear normal and shear joint behavior between jointing planes. The mathematical descriptions by Morland based on strain partitioning among matrix material and joint sets allow multiple joint sets to be included in the model. However, the initial effort by Thomas to implement Morland's mathematical model included only a single set of joints. To make the material model reflect more realistically the field characteristics, the current work extended Thomas's model to include orthogonal sets of joints. The nonlinear elastic normal joint behavior is retained in the present model. Joint shear response was treated as linear elastic in the shear stress versus shear displacement relationship prior to attaining the stress level governed by the Coulomb friction criterion. Beyond this critical stress value, a horizontal line is assumed in the work of Thomas for the shear stress versus slip displacement relationship such that the shear stress remains constant while the slip displacement increases. Motivated by experimental observation, the current work generalized the shear response to allow a line with finite slope to govern the slip behavior beyond the critical stress level. The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Formulation of the Continuum Model The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Let us focus our attention on the set with normal n first. Let the jump dilation displacement and jump slip dasplacement associated with the [ ]

Jan 1, 1986

By Peter Keppler, Charles Jackson

WHY DO AN AUDIT? There is increased enforcement of environmental laws and regulations at State and Federal levels with attendant steep fines and even the possibility of jail sentences. We are all aware of environmental and public health and safety incidences (i.e., Love Canal, Bhopal) which have led to stringent laws and regulations (i.e., CERCLA, RCRA, SARA). In some cases, the courts have specified that a company institute an audit program as a condition of settlement of claims which related to lack of environmental control. The U.S.EPA issued an Environmental Auditing Policy Statement in the November 8, 1985 Federal Register (pp. 46504-46508) which encourages the use of environmental auditing by regulated entities. Elements of what EPA considers to be an effective environmental auditing program are outlined and briefly explained. These factors combine to indicate why there is a growing number of companies which have instituted an audit program. Briefly, the program can and should be used to monitor compliance with environmental regulations and corporate policy, to prevent violations, to improve policies and procedures, to raise the level of environmental awareness, to encourage communication among operations and all management levels about environmental problems, and to measure risks and control costs. AMAX Inc. has had an environmental audit program since the early 1970's. The AMAX Environmental Affairs Department, working with the Law Department, oversees and coordinates environmental audits and analyzes the findings which an audit reveals. Facilities are audited on a regular schedule; those having the greatest potential for environmental liabilities are audited at least annually; other facilities are audited less frequently. The question of who performs the AMAX audits was settled in favor of the audit team being independent of personnel from the facility being surveyed. Other methods of auditing could be the following: - Independent contractor (Appendix A) - Combination of independent contractor and in-house staff - Self-audit by site personnel The merits and demerits of who should conduct the audit can be analyzed to suit your particular needs. Next you need to decide on the procedure for the audit and the form for reporting and follow up. Environmental publications referenced in Appendix B can be helpful to you at this point. After deciding on the form of auditing, a schedule is prepared and followed to the closest extent possible. This schedule should be published and distributed to the sites so facilities know when they are being audited. This is not designed to be "a game of hide and seek." Various elements of the AMAX Audit Program are as follows: Team selection Pre-visit preparation Site visit Exit interview Report Using the audit Follow-up Team Selection The usual make-up of the team is the audit manager, the environmental specialist who normally provides assistance to the site or has knowledge about the operation, and a legal representative if his or her schedule allows. The legal representative will review the findings of the audit team if a personal visit is not timely or necessary. Size of the team can be expanded, but a minimum of the audit manager and the environmental specialist is best. Two sets of observations are better than one. The environmental specialist can also provide the rapport which is beneficial to creating the appropriate tone so that the site people will be as cooperative as possible. This is not to be an antagonistic exercise.

Jan 1, 1991

By C. Huang, S. Lin, Y. J. Wang

Introduction A mine characteristic curve is of great importance for both theoretical analysis and daily management of a mine ventilation network. Ventilation engineers are well acquainted with the ways of obtaining and using a mine characteristic curve that is conventionally associated only with single-fan networks. However, for a multiple-fan network, difficulty has long been recognized in defining the curve, not to mention, obtaining or using it. To extend the concept of mine characteristic curves for a multiple-fan network, a subsystem-based approach has been introduced by Wang (1992a). He defines a subsystem characteristic curve for a multiple-fan network and discusses the numerical procedure for constructing the curve. A graphical method of obtaining a subsystem characteristic curve for serial-parallel, multiple-fan networks has also been accomplished (Wang, 1992b). In spite of the maturity of the fundamental concepts related to and the numerical analysis tool for a multiple-fan ventilation network, information regarding the related laboratory tests is very scarce. To make up this gap, laboratory experiments have been done by using a two-fan experimental network. This paper presents the methodology and major findings regarding the construction and features of a subsystem characteristic curve. Characteristic curves and measurement fundamentals A characteristic curve A characteristic curve is a graphic presentation of the relationship between any two variables of a two-terminal component. It is typically defined in the form of a quantity-pressure curve for a ventilation component, which can be a single branch (airway), a fan, a regulator, a portion of a network or even a whole network. If a component is a single branch, the curve is called a branch characteristic curve. If it is a fan, then the curve is called a fan characteristic curve, and so on. Figure I illustrates the characteristic curves of some typical ventilation components. A general method for obtaining a characteristic curve from measurement is to apply an adjustable-pressure source between the two terminals of a component and measure the quantities corresponding to the different pressures. Mine characteristic curve A single-fan network can be easily divided into two ventilation components, the fan and the remaining network. The latter consists of only branches and regulators. Under this subdivision scheme, two characteristic curves can be constructed. They are the fan characteristic curve and the characteristic curve of the remaining network. The latter is referred to as the mine characteristic curve or the system characteristic curve. Although the general method for constructing a characteristic curve from measurement can be applied to obtain a mine characteristic curve, there is a shortcut for constructing the curve by introducing a mine resistance factor R. It is a constant if all of the resistance factors in the network are constant. R relates mine pressure H with quantity Q as in: H=RQ2 (1) For a given R, Eq. (1) can be directly used to plot a mine characteristic curve by assigning a series of Q values and calculating the corresponding H values. Hence a shortcut to constructing a mine characteristic curve is to measure one set of mine pressure H and quantity Q values, calculate the mine resistance factor R using Eq. (1) and then plot the curve. Subsystem characteristic curve Applying a similar scheme as is used for a single-fan system, divide a multiple-fan network into two components, a fan under consideration and the remaining network that contains all the other elements (branches, regulators and remaining fans) of the network. The fan under consideration

Jan 1, 1994

The paper describes the procedure of data inquiry on the structure of mineral production in Austria and selected results. Goal of the endeavor was to gain more tangible insights into the mining industry as a basis for regulation balancing economical, ecological and social aspects.

Jan 1, 2006

By Bijan Taheri, Behrouz Maghsodi, Monireh Heshami, Reza Kohan

A common problem recently encountered with the increase in the rate of input feed at Enrichment Plant 2 of the Sarcheshmeh Copper Complex is the loss of value to the tails, translating to lower recoveries. The feasibility of the direct transfer of part of the high-grade concentrate from rougher stages to an appropriate position along the circuit was studied, and two positions were proposed for direct transfer of the concentrate. One position was the feed flow into cleaner cells, and the other was the feed flow into the recleaner cell. The results indicated that transferring the concentrate from the first unit of the rougher stage to the feed flow into the cleaner cells was feasible, with no limitations, while the second position required the installation of a set of hydrocyclones. It was found that the transfer of concentrate to the proposed positions not only addressed the problem of limited cell capacity, resulting in debottlenecking of the circuit, but also improved metallurgical separation efficiency up to 1.4%.

By Nikhil Dhawan, Shrey Agrawal, Veeranjaneyulu Rayapudi

India’s steel vision of 2030 requires a huge amount of quality iron ore. The utilization of low-grade iron ores such as banded iron ores will play an important role to achieve the same production. The absence of alumina impurities in the banded hematite jasper (BHJ) ore provides it an edge over other low-grade iron ores. The conventional beneficiation techniques such as magnetic separation and washing were found to be ineffective to produce suitable feed (Fe ~ 60%) for the blast furnace. It was found that microwave exposure provides significant enrichment to the low-grade iron ore and can be used as a pretreatment step in the beneficiation of similar low-grade iron ores. The above study reveals that hematite phase is susceptible to microwave exposure which enhances the separation of iron values from impurities. Under optimum conditions, an iron-enriched concentrate with 61% Fe, 85% Fe recovery at 50% yield can be achieved from BHJ feed ~ 38% Fe. The pretreatment process for BHJ beneficiation includes only microwave exposure without any chemical additive and may prove economical and industrially feasible.

By L. Yuan, J. Soles, D. Bahrami, W. Tang, R. Thomas

Mine equipment fires remain as one of the most concerning safety issues in the mining industry, and most equipment fires were caused by hot surface ignitions. Detailed experimental investigations were conducted at the NIOSH Pittsburgh Mining Research Division on hot surface ignition of liquid fuels under ventilation in a mining environment. Three types of metal surface materials (stainless steel, cast iron, carbon steel), three types of liquids (diesel fuel, hydraulic fluid, engine oil), four air ventilation speeds (0, 0.5, 1.5, 3 m/s) were used to study the hot surface ignition probability under these conditions. Visual observation and thermocouples attached on the metal surface were used to indicate the hot surface ignition from the measured temperatures. Results show that the type of metal has a noticeable effect on the hot surface ignition, while ventilation speed has a mixed influence on ignition. Different types of liquid fuels also show different ranges of ignition temperature. Results from this work can be used to help understand equipment mine fires and develop mitigation strategies.

Mar 2, 2022

By C. Cristoffanini

A real-time transient pipeline simulation was used to model the operational pressure response in the concentrate and tailings pipelines of the Minera Los Pelambres copper mine in Chile. A high-fidelity simulator was needed to train the operators on safe operation of the pipeline for different scenarios. A simulator that solves the transient equations was used to dynamically predict the pressure and flow throughout the pipeline to provide real-time responses to operational changes such as opening or closing a choke valve, or sending a water batch. Slurry rheological properties were incorporated into the model. This paper presents the technical background of the pipeline simulation model and the study of slurry properties. The paper shows the results of the transient simulation for different operating scenarios such as start-up, shutdown and leakage, by presenting the hydraulic gradient curves for each case. Finally, the paper briefly presents how the simulator was connected to an emulated control system and used to train the operator, it demonstrates the most effective tool available to learn to resolve undesirable conditions.

Feb 23, 2014

By Ian Farrell, Josh Stowe, Eric Wingeard

Tailings transport system design is generally based on identifying the minimum and maximum process boundary conditions for pump selection and pipeline sizing. The approach is robust and well-proven. However, the approach has the potential to skew selections to operating scenarios that have a very low likelihood of occurring, such as the combination of high solids throughput and low tailings solids concentration. The approach can result in a tailings transport system design that is overly conservative. A probabilistic method-based approach captures the independent variability of design inputs and the combined likelihood of outcomes. This approach identifies the process conditions that have the highest likelihood of occurrence and are most applicable to equipment and pipeline selections. An outline of a probabilistic-based approach to tailings transport system design and the resulting selections is provided in this article. The probabilistic-based system design is compared to the outcomes from the traditional approach. The benefits and challenges to this approach are discussed and recommendations for utilizing this approach for tailings transport system design are provided.

Mar 31, 2021