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By B. Briggs

Over the past 15 years, the tunneling industry has pushed towards a higher degree of mechanization in nearly every phase of construction. The overall objective of the mechanization was to increase production and the level of safety in tunnel operations. However, the overall complexity of some systems have been a hindrance to a seamless transition to the newer technologies as increased maintenance requirements and re-training of skilled workers has altered the benefit curve for some innovations.

Jan 1, 2010

By A. F. Peterson

There is no single mining problem at Benson that does not exist at some other mine. There are four, however, that require special attention primarily because they occur together and have an influence on each other. These are the nature of the mineral occurrence, the shape of the ore body, the operating schedule, and the climate. It is the purpose of this paper to describe mining practices in relation to these four factors. Iron ore was first noticed in the Star Lake area early in the nineteenth century. Prior to Jones and Laughlin leasing the facilities built by the Defence Plant Corporation, several companies tried to mine the ore body but gave it up as uneconomical. While there is a little high grade (40%) magnetite, most of the ore contains 20 to 25% iron and not enough was known prior to World War II to design a profitable operation. By 1943, and certainly in the years that followed, technological developments in ore dressing and mining not only put the magnetite into the category of a commercial ore, but made possible the concentration of the non-magnetic iron mineral, martite. This last development nearly doubled the ore reserve. Jones and Laughlin bought the DPC holdings in 1946 and has since expanded the plant to its present capacity of 4,400 gross tons of concentrates daily or 1,600,000 gross tons per year. Magnetite makes up 62% of this production at the present time, but it will be necessary before long to bring martite production up to about 45% of the total because of the ratio of the two ores in the reserves. To keep the plant supplied, 14,000 to 15,000 tons must be mined and crushed daily, with a ratio of concentration that varies from 2.8 to 3.4. The ore body is 12,000 feet long and varies in width from 600 to 1,500 feet. The waste rock is, for the most part, a granite gneiss, and the overburden, of which little is left, is a glacial drift sand. For the entire reserve, there is a half ton of rock for every ton of concentrate, but the stripping ratio is more than one to one at present because of the existence of more rock in the upper mining levels in relation to the ore. The dirt stripping or development work that cannot be handled by company facilities is contracted to an outside firm. The need for this diminishes every year and will soon disappear. The deposit looks like a "J" in plan, with the long leg running approximately north and south and the short leg to the west. The primary crushing plant, consisting of a 54" gyratory followed by two 18" gyratories and a 1,500 foot conveyor belt to the fine crushers, is located on the third level where the long and short leg of the mine meet. The widest part of the pit lies just the north of the crusher. The mine is operated on a lease that expires in 199l0 There are two fee owners, the Benson Iron Company, which owns slightly overhlf of the reserves, and the Newton Falls Paper Company, which owns the balance. There is no appreciable difference in the mining on the two fees, so the ore is removed in strict proportion to calculated reserves during each year. Basic mining equipment consists of eight 45 yard electric shovels, a fleet of twenty-five 22 ton end dump trucks, eleven churn drills for nine inch blast holes, and two small percussion drills for four to five inch holes, There are the normal auxiliary items, such as dozers, graders, wagon drills, and two drop-ball cranes. Power is purchased and, where practical, is used at 4100 volts. Pit drainage pumps can handle a maximum of 11,500 GPM from the several sumps, but water is a problem only during the spring or when a sudden thaw follows a heavy snowfall.

Jan 1, 1958

By Hal McVey

Introduction The role of marketing in the minerals and mining industry takes on different degrees of importance depending on the commodity, but nowhere are sales and marketing more important than in industrial minerals. This article compares industrial minerals marketing with the marketing of other mining and mineral products. Marketing in Mining Some broad generalizations on the marketing of industrial minerals in relation to other mineral products can be made without getting bogged down with exceptions to generalizations. Two totally different areas of mineral production are crude oil and natural gas, and metals, including ores and concentrates. Although these commodities are the basis for two completely different industries, they share two things in common from a marketing standpoint: • Their value per unit volume is usually high enough so that they can be transported great distances. • Their specifications are readily definable and, therefore, the quality of a standard product from a production run can be communicated by stating certain chemical and physical features. This permits sales to be consummated by telephone, telex, and letter, without the need to pretest the products under use conditions. In regard to the first item, industrial minerals, as opposed to oil, gas, and metals, are in most instances site specific. Location of the point of production in relation to the point of use is of paramount importance based on a generally lower unit to volume value. This means that transportation is a major factor, with the cost of getting the mineral to market commonly exceeding its f.o.b. value. Coal marketing has many characteristics in common with industrial minerals. Coal sales can es-

Jan 11, 1983

By Robert E. Mazurak

Mines and plants for sale, downsizing, bankruptcies, consolidation, slab imports, minimill growth displacing traditional integrated steel-making. These are some issues for North American iron ore and integrated steel producers. But the blast furnace still remains the workhorse of the ironmaking industry. And direct reduction and other alternate ironmaking technologies have yet to make any serious inroads in North America. How come? This article addresses the current state of primary ironmaking in the changing North American steel industry, the direct reduction market and new technologies under development that may hold some promise.

Jan 1, 2003

By Thomas J. Kuli, Tim Rape

When a fan or blower breaks down or becomes worn, customers have two choices. They can replace it or they can have it repaired. In the past, replacement was the preferred option, especially when the equipment was severely damaged or worn. Now, however, customers are discovering the benefits of repairing or rebuilding. Even when the cost of repair is more than 60 percent of the cost of a new fan, customers are choosing the repair option. The cost savings can range from 20 percent to 80 percent. In many cases, the quality of the repaired part or component will exceed the quality of the original. This is because repair engineers have an advantage over the original designers. They can see how the existing fan performed — or failed to perform — in a specific application.

Jan 1, 2005

By John L. Kaplin

The underground construction for the Phase I Combined Sewer Overflow(CSO) Project is on an impressive scale by any measure, appearing more so in a midsize city like Providence, RI. The Narragansett Bay Commission recently completed $350 mil-lion in construction to improve the water quality in Narragansett Bay. This project included a number of serious challenges, delays, and disputes. Looking back on this complex project completed within budget, it is hard to consider the work as anything other than a success. Along the way, this outcome did not always appear certain.

By S. Ersayin, I. Iwasaki

The application of a magnetic field was shown to be effective in controlling iron losses in a pilot-scale cationic silica fIotation in the processing of magnetic taconite concentrates. The design of a magnetic field distribution device and batch flotation test results using a 1.42-m3 (50 cu ft) WEMCO flotation cell are reported. Major losses of iron units in froth products were in the -25-µm (-500-mesh) fraction, and the application of a magnetic field decreased the flotation of fine magnetite, thereby improving the selectivity of separation. The "as-received" sample was sufficiently magnetized, and no further benefit was gained by the magnetizing treatment. The selectivity was somewhat adversely affected by demagnetizing the sample, though its effect was minimal due to the magnetic field. The device is simple in construction, low cost and may be readily installed in existing equipment. Key words: Iron ore, Flotation, Taconite concentrates, Cationic silica flotation, Magnetic field, Flexible magnetic sheet, Magnetizing, Demagnetizing

Jan 1, 2003

By R. D. Rein

The Henderson mine is a large continuous panel caving operation in central Colorado. The orebody is roughly 760 m by 910 m and will be extracted from two production levels. Each level is divided into three north - south panels 244 m to 317 m wide. The general arrangement of a production level and its associated undercut drifts is shown in Figure 1. The production drifts (3.6 m by 3.7 m) are spaced 24 m apart center to center and have undercut drifts (3.4 m by 3.8 m) 17 m directly above them. The production drifts are interconnected with drawpoint crosscuts (4 m by 4.3 m) driven on 12 m centers. Drawpoint crosscuts receive substantial brow steel and concrete support prior to undercutting. The brow steel is a 15 cm by 46 cm wide flange beam with a 2.5 cm wear plate to box in the 'cave' side of the beam. The concrete is a minimum of 0.3 m thick and the batch design results in 27 500 kPa strength. The finished drawpoint opening is 3.7 m by 3.2 m with a choke area of 3.7 m by 2.4 m. (Figure la) Undercutting and bell formation is accomplished by blasting rings of 7.6 cm holes drilled from the undercut drifts. The rings have a burden of 2.0 m and six rings develop one complete bell.

Jan 1, 1985

By James R. Arnold, Cindy S. Jones, Michael F. Gleason, John O. Marsden, John G. Mansanti

INTRODUCTION The Chimney Creek Gold Mine (Gold Fields Operating Co. - Chimney Creek) is located 47 miles northeast of Winnemucca, Nevada, at the northern end of the Osgood Mountains. The operation is a wholly owned subsidiary of Gold Fields Mining Corporation, the North American branch of Consolidated Gold Fields PLC, London, England. The plant started up in November, 1987, less than three years after discovery of the orebody and three months ahead of schedule. Ore is mined in an open pit and is processed by combined dump leaching and milling techniques for gold and silver recovery. The mine is set to produce approximately 150.000 ounces of gold and 50,000 ounces of silver per year over a 12 year life at current reserve estimations. The mine was designed and constructed at a cost of $79.3 million with engineering and construction services provided by Davy McKee Corporation, San Ramon, California. Key Gold Fields operating staff were involved in the design of the facility from the start of the project: The Mine Manager, Plant Superintendent, Plant General Foreman, Maintenance General Foreman and Chief Metallurgist were all involved full time on the project within 5 months of the first ore discovery. Emphasis was directed at optimizing operating efficiency and in particular minimizing labor costs in the plant. It was recognized that a high level of instrumentation and control would be required to achieve this. The risk associated with the instrumentation and control systems implemented was to be minimized by using equipment and systems that had been proven in industry while utilizing the most cost effective, state-of-the-art technology available. The reliability of the overall control system was considered to be critical in view of the cost of downtime associated with the gold extraction plant. BRIEF PROCESS DESCRIPTION The dump leaching process treats approximately 1.2 million tons per year of low grade ore at an average grade of 0.035 oz/ton. Run of mine material is dumped on a lined leach pad and weak cyanide solution is applied by drip irrigation. Pregnant solution run off is pumped to carbon columns in the milling plant for gold recovery and the barren solution returned to the dump leach circuit. Average gold recovery is 60%. This process has little instrumentation and control associated with it. The milling operation treats 700,000 tons annually of higher grade ore (0.200 oz/ton initially, dropping to an average of 0.135 oz/ton after first two years). Recovery is directly related to head grade (fixed tail assay effect) and currently averages 96%. A single pass through a jaw crusher reduces run of mine ore to minus 12 inches. The ore is stockpiled and reclaimed by loader for grinding in a two-stage milling circuit consisting of a SAG mill and ball mill, the latter in closed circuit with hydrocyclones. Cyanide and lime are added into the SAG mill to start dissolution of gold as early as possible in the circuit. The ground product leaves the milling circuit at approximately 78% minus 200 mesh and is fed to an unique "double thickener" leaching-recovery circuit. This circuit has been discussed in detail in a paper by J. G. Mansanti et a1 (1). Two thickeners are arranged in counter- current configuration with three leach tanks. Overflow solution from the first thickener is treated by carbon-in-columns (CIC) for gold recovery with 85% of the soluble gold recovered onto this carbon. Underflow slurry from this thickener is pumped to the leach tanks, with a total retention time of 12 hours, and then gravitates to the No. 2 thickener. Overflow solution from the second thickener is used as a wash in the first thickener. Underflow slurry from the second thickener is treated in a carbon-in- pulp (CIP) scavenging circuit to recover the remaining 15% dissolved gold. Gold-loaded carbon from both the dump leach and milling circuits is stripped in batches using the Zadra hot caustic- cyanide elution process. Gold (and silver) is recovered from the hot strip solution by precipitation with zinc dust and the product recovered on Funda pressure filters. The precipitate is retorted to remove any mercury and then smelted into buttons. The buttons (approximately 80% gold, 15% silver) are shipped to an independent refiner in Salt Lake City, Utah, for further treatment.

Jan 1, 1990

By M. D. Baker

Coal-water slurry preparation requires fine grinding and cleaning of coal by flotation. Finer grinding leads to increased ball wear and its effect on the surface properties of coal becomes of concern. Marked ball wear tests were performed to study the effects of oxygen, pH, the soluble species of coal and the addition of pyrrhotite on ball wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel balls during grinding. Electrochemical measurements on a mild steel electrode in coal slurries and SEM observations of grinding ball surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1989

By M. P. Hoffman

The U.S. Bureau of Mines is developing a roof bolter with a computer-controlled drill head that will increase the safety of roof bolting in underground coal mines by allowing miners to be relocated to a safe area. To ensure secure anchorage, acceleration and strain data are broadcast from an instrumented drill steel to a data acquisition system. These data are analyzed, correlated, and transformed to pro-vide information about roof strata, then are sent to a supervisory computer executing National Institute of Standards and Technology's real-time control software. The supervisory computer sends setpoint commands to proportional-integral-derivative control loops to control drill thrust, position, revolutions per minute, and torque.

Jan 1, 1994

By M. Zuckerberg, E. Mader, R. Pasyar

We describe a new software product designed for the net present value optimization of multi-open-pit blended ore operations in which it is desired and/or necessary to dump some or all of the waste rock produced in the course of operations back into the voids created in the process of ore extraction. The software product simultaneously decides over the entire life-of-mine which material to mine in which year, once mined what to do with it, and where to put that material which it has decided to waste, all subject to annual blend and capacity constraints.

Jan 1, 2007

By Raivo Maripuu

The Boliden Group encompasses Sweden's foremost operations related to the mining and production of copper, lead, zinc, precious metals and metallic by- products. It is also the dominant swedish producer of sulphur-based heavy inorganic chemical products and fertilizers and has an international trading organization covering, in adition to the group's basic products, industrial minerals and oil. Boliden's activities in- clude the marketing of proven Boliden technique and know-how. Boliden Metall - the mining and metallurgical company within the Boliden Group - produces about 13 million mtpy of ores at mines in northern and central Sweden. Boliden has, over the years, become a specialist in processing poly- metallic sulphide ores and its eight concentrators presently serve 15 mines. Boliden has a long history of close cooperation with Swedish and foreign manufacturers in developing new products and processes.

Jan 1, 1979

By Christopher Haycocks

Self-supporting, open stoping underground mining methods are some of the earliest, starting with the prehistoric flint mines of Europe and the Egyptian gold mines of Nubia in the time of the pharaohs. When the early miner created an opening, it had to be inherently stable and self-supporting to enable him to continue. Therefore, as mining progressed beyond simple gophering, self-supported open stoping methods were devised to meet the needs of individual ore bodies. Timber for support appears in mines as early as 1000 BC, but this was for no more than local ground control. The ingenuity of mining engineers through history has so refined open stoping methods that today they produce more tonnage than any other mining system. Self-supported open stoping finds its application in moderate to strong rocks that exhibit little jointing or fiagmentation. Good back, hanging wall, and footwall conditions that require no more than incidental support are an essential part of these mining methods. Open stoping methods find applications in all inclinations of ore body from flat to vertical, and where ore movement may be either mechanical or under the influence of gravity. Table 18.0.1 demonstrates the range of ore bodies suitable for open stoping, with particular reference to their dip and the deposit thickness. Most of the flat-dipping applications use ore pillars for overall support and ground control that may be recovered under some conditions after completion of normal stoping practices. In steeper ore bodies, rib, crown, and sill pillars used to block out the ore may be recovered subsequent to the completion of stoping. Open stopes are frequently filled to facilitate pillar recovery. Two of the methods, vertical crater retreat (VCR) and shrinkage stoping, utilize fragmented ore for temporary support in the stopes. In these two cases, the stope is not strictly open until after drawdown.

Jan 1, 2008

By R. C. Kirkman

Your interesting and well-written paper brings up the issue of the purpose or use of a mineral property appraisal, specifically the value of these evaluations when the quality and quantity of the mineral resource to be exploited have not been thoroughly investigated. I am not a practicing professional in regards to valuation of limestone investment opportunities. I simply wish to make a few generic observations about the appraisal process in order to stimulate meaningful thinking by appraisal professionals whose reports may be reviewed by professional investors and "laypersons" alike. It is my contention that the analysis given in your paper is very thorough, considering the data that was made available to you. But I would not like to be the person responsible for investment decision making without having a feel for the risk involved. Therefore, the reviewer must classify this type of analysis as relatively "subjective" because they have not received an indication of the inherent risk involved in exploiting a mineral resource. This risk can best be quantified by using probabilistic methods in conjunction with the quality and quantity of the mineral to be produced. Most appraisals passively ignore this problem. Specifically, you have accurately identified the various costs and values entering the economic appraisal process. These can usually be quantified with a great deal more certainty than the capability of the resource to provide 25 years of quality material. Also, in Cases A (West Virginia)and B (Alabama), you are fortunate enough to have previous operations data. What if there had never been production from these properties? How does a potential mineral property investor evaluate the resource capability to meet various projected financial outcomes without spending a good deal of up-front capital to drill and delineate enough quality resources for a 20-plus year operation. These questions pose a substantial risk to any potential mineral investor. Only probabilistic methods should be used to quantify this type of problem, short of drilling and metallurgical testing. I might be considered a "layperson," not being familiar

Jan 1, 1991

By Milton E. Wadsworth

The evolution of engineering education and research has been profoundly influenced by computer technology and has concomitantly followed changes in this technology. Today, virtually all faculty have access to at least two hierarchies of computers: desk personal computers and at least one echelon higher (workstations or a variety of mid-sized computers). Most faculty have access to three or even four hierarchies: the two listed, plus super-mini and super computers. The ready availability of computers at a low cost has increased dedicated and site-specific computer technology. This has permitted universities to move into the field of macro-engineering, to address increasingly complex problems in resource recovery, manufacturing and many other areas, including important societal problems, like the environment. The creation of university research centers indicates the growing importance of macro-engineering involving large systems of interactive components. Funding agencies have increasingly favored such centers since they cross disciplines, generate inter-university consortia and foster university-industry programs.

Jan 1, 1992

By A. C. Lyons, A. J. Reed

INTRODUCTION A trend which is obvious in the United Kingdom and is thought to be evident in other parts of the Western world is the disproportionate rise in the cost of tunnel mining labour compared with other tunnel cost increases. This disproportionate increase in labour costs has been accompanied by, and may be the result of, a shortage of skilled working labour. To combat this problem there has been a steady increase in the use of machines for excavation and for the erection of tunnel linings to keep the amount of skilled labour working below ground to a minimum. The typical tunnelling cycle, where the ground needs continuous support can be excavation, temporary support, temporary lining, grouting and permanent lining. It is obviously an advantage to combine as many of these operations as possible and carry out as much as possible by machine. Machines have been developed which will, either alone or used in combination with a shield, excavate and, when necessary, temporarily support the excavation. If a segmental lining is used, it can be so designed that it will form the permanent lining and reduce the cycle time and skilled labour requirement to a minimum. In cases in which the ground can be cut accurately to a smooth profile and will stand without support for a sufficient time, the lining can be expanded against the ground and the necessity of grouting eliminated. In cases in which ground will not stand without support, the usual method is to use a bolted lining and to grout behind it preferably as the shield is shoved forward. Whichever technique is used (this is largely determined by the ground) it is an advantage to make the segments as large

Jan 1, 1974

By J. Nowak

Polish power industry is based on brown and hard coal combustion and transferring the heat into electric power. Over 99% of lignite is used as a fuel in power plants. Lignite is mined on in open pits. Therefore very deep (for example 300 m in Belchatow open pit) excavations having great volume are formed. Thus such type of mining has the impact on land degradation. In order to reduce this effect, at the earliest possible moment the cap rocks are dumped in the pit but at the safe distance from the mining face. Due to the big amounts of lignite delivered to the power plant, there are shortages of solids for filling the pit after completing the mining operations. Geotechnical properties of dumped combustion by-products depend on the lignite type, combustion technology and ashes haulage methods. The paper presents lignite combustion methods used in Poland and their impact on properties of ashes and methods of their transport determining the parameters of dumped wastes. Geotechnical, physical and chemical test results concerning transport and deposition of hydraulically active ashes from the Belchatów power plant are presented. The critical role of geotechnical properties in selecting the deposition technology and post mining management of open pit excavations was showed. The importance of filling the post-mining spaces for restoration the useful function of brown fields and for neutralization of negative effects of mining activity, was underlined.

Jan 1, 2006

By Omar A. Muhtadi

Brohm Mining Corporation, in conjunction with Geobiotics, Inc. has nearly completed a pilot heap biooxidation test on sulfidic ore from the Gilt Edge Mine near Rapid City, South Dakota. Some results from the pilot testing have shown the correlation between the extent of biooxidation and the increase in cyanide gold recovery seen in the laboratory. Bench scale testing showed approximately a 1: 1 correspondence between percent biooxidation and percentage increase in gold recovery. The economics of large scale biooxidation were also evaluated in terms of increased gold recovery versus the time and cost of biooxidation. In the pilot test, the rate of biooxidation became limited by the acid water neutralization system. Later in the test, measures were taken to overcome this problem. Results from bench scale column bioleach testing showed that the Gilt Edge sulfide ore is quite amenable to biooxidation with a substantial increase in gold recovery with just partial biooxidation. Direct cyanide gold recovery of 51 % on ore crushed to -3/8" was enhanced to 82-85% after oxidation of37% of the sulfide as measured by iron. Laboratory experiments also showed that the slow rate of biooxidation of this ore could be accelerated by removal of metal sulfate build up from the leach liquor. The combination of these normally non-toxic metals became inhibitory to biooxidation if not removed by the neutralization circuit.

Jan 1, 1995

By John F. MacDonald

This paper describes the driving of a 400 m long by 25 m diameter highway tunnel through sensitive, overconsolidated silts and clays. The design concept requires the construction of the permanent support system, consisting of 24 concrete filled perimeter drifts, before excavating the mass core. General construction procedures used during the construction of the perimeter drifts are described.

Jan 1, 1985