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By Richard R. Klimpel

In this paper, the old and the new commercially available reagent chemistries for the improved flotation of sulfide minerals will be summarized. The reagent classes discussed are those that meet three criteria: 1) they are being commercially used and/or large scale plant tested in North America in the last few years; 2) they are clearly different in chemical structure than commonly used commercial reagents of the last few decades and are not simply mixtures of existing reagents and/or simple changes in cation, alkyl group size, etc. and 3) the structural formulae are clearly specified in the public literature.

Jan 1, 1994

By Marcel Haffen, Jean Janin

The purpose of grouting is to modify the permeability and strength characteristics of the subsoil in such a way that the planned structure can be efficiently constructed at a given location. This technique, which originally underwent considerable development in the field of dams construction is constantly evolving and it becomes more and more important in urban zones of intensive underground development for projects such as transport tunnels, stations, car parks, ect. Grouting becomes more and more indispensable whatever the natural characteristics of that subsoil ; such is the case particularly when the planned work runs through cohesionless granular soils, usually water-bearing such as alluvium, sands, disturbed ground, fill material, etc. The selection of the grouting method and the extent of treatment required at depends on two fundamental factors. 1º) nature and behaviour of subsoil to be treated. There is no need to stress the necessary of a good knowledge of geotechnical, hydrological and chemical characteristics of the ground to be treated. At the present time the specialists in these fields have available numerous methods of analysis, either laboratory or field tests, which enable to evolve a suitable treatment.

Jan 1, 1997

By S. K. Kawatra

In this paper three methods of on-stream analysis 1) Radiometric techniques, 2) X-ray tube techniques and 3) Neutron activation method are reviewed. Advantages and disadvantages of each method are discussed.

Jan 1, 1984

By D. Altizer, E. Thompson, K. F. Unrug

Because of frequent sudden changes in the geologic composition of strata, the extrapolation of rock properties obtained from core samples to the surrounding areas can cause problems. To address this issue, a method of rapid strength testing in situ using a borehole penetrometer is being developed. This method, as opposed to conventional laboratory testing, does not require rock samples to be retrieved and handled/machined before testing. Rock strengths are determined di¬rectly on the drill-hole wall. The latest development is a borehole penetrometer that requires only a 38.1-mm- (1.5-in.-) diam hole. The small diameter of the penetrometer body allows for the drilling of test holes with production mine equipment such as a roof bolter. The new penetrometer allows for the possibility of a broad application in coal mines, as well as in hard rock mines and tunneling. The principles of the apparatus are described and are illustrated with examples of its applications.

Jan 1, 2002

By Alfredo Dammert

The paper presents the results of a model built at the World Bank in order to analyze the aluminum industry. Bauxite demand for the year 2000 is estimated as a function of alumina refineries' requirements and of non-metal uses for bauxite. Bauxite supply by countries or regions depends on economic factors such as investment costs, operating and transportation costs, as well as on tariffs and levies. Various scenarios are considered as a result of varying the assumptions of the model.

Jan 1, 1984

By E. Yuksel

Noted as one of the 20 major economies of the world, Turkey is a semi-arid plateau between the Eurasian and the African continents. With its surface area of 780 thousand sq km, it supports a population of 70 million people. While the mining history of Turkey can be traced back as far as 7 000 B.C., mining currently generates only 2% of Turkey’s gross national product. Turkey has 77 of the 90 principal minerals that are mined world-wide. Currently, some 5 000 mine occurrences including copper, lead, zinc, iron, gold-silver, chromite, sepiolite, mercury, and coal deposits, soda ash, marble, zeolite, feldspar, magnesite deposits, as well as the world’s largest known borate deposits, have been discovered and partially explored.

Jan 1, 2004

By Stephen P. Harrison

The ventilation of coal mines has long been a major challenge for the mining industry. Prior to the 1969 Health and Safety Act, mine ventilation planning was almost entirely handled by individuals in mine operations and engineering who had extensive practical experience. Their background and expertise was sufficient to deal with existing ventilation problems and planning. A recent decline in the number of qualified individuals combined with more stringent state and federal regulations have necessitated a thorough engineering oriented approach to ventilation in mine planning design. To plan for an existing mine, a thorough ventilation survey must be conducted to determine the capabilities of the existing ventilation network. A ventilation survey also provides considerable useful data for long range planning. Essential information such as friction factors, entry resistance, and potential ventilation problem areas is gained from the survey data. With this information a comprehensive computer analysis can be conducted to evaluate alternative mine plans. This evaluation of mine plans is essential to minimize the number of shafts required while still maintaining the quality of mine ventilation. Using an existing mine as an example, this paper outlines a detailed procedure for organizing, con-ducting, and evaluating a ventilation survey. In addition, specific ventilation problem areas are isolated and alternative methods for their solution are considered. Furthermore, a long range mine plan is evaluated and the most feasible variation of the plan is selected.

Jan 1, 1980

By Palmer C. Sweet

Mining-related wastes, which are increasing, are being utilized more and more as valuable resources in Virginia. The Environmental Protection Agency (EPA) divides mining-related wastes into two categories: those generated from mineral extraction and beneficiation and those generated from mineral processing. Materials from both categories are produced in Virginia, where waste (by-product) materials are present at a variety of mining sites and processing plants; some of which have been exploited for various uses in the past and/or present. These materials include: used concrete recycled for roadbase material; pyrite coated with magnetite for use in portland cement; minor amounts of fly ash for use in concrete block, lightweight aggregate, and flowable structural fills; granite and diabase quarry fines for use as agricultural and asphalt filler; lime kiln dust for use in neutralizing and stabilizing coal refuse; soapstone aggregate for use in terrazzo heat retention panels; kaolin for use as a filler product and as an ingredient in white cement; slate quarry fines used as landcover and combined with aggregate for crusher run and as a filler in asphalt; and coal refuse for use as fuel in a lightweight aggregate plant. There are some materials available that have never been utilized, although several ideas were investigated to turn them into usable commodities. One such material is a high-alumina scrap produced as a by-product at a ferrovanadium processing plant. However, large quantities of waste materials from metal mining, industrial mineral, and fossil fuel operations remain to be disposed of in an environmentally safe and economic manner. In 1989, almost one million tons of fly ash were produced from burning of coal at eight coal-fired power plants in Virginia. Present uses for this waste such as an ingredient in concrete block, concrete aggregate, and in structural fills cannot dispose of all the available material; however, increased use of fly ash as a soil/rock substitute for structural fills and embankments may solve the problem of its disposal. Another waste material is calcium carbonate precipitate paste produced at a lithium carbonate processing plant and presently being used for back filling an on-site inactive underground limestone mine. Flue gas desulfurization (FGD) wastes in the form of CaS04 will probably increase threefold. If this material contains a minimum of 95 percent gypsum and negligible chloride, it may have a value to a wallboard manufacturer as we move toward the year 2000. Thought must be given how this increasing waste can be disposed of in an environmentally safe manner.

Jan 1, 1995

By A. Ang-Ug, L. Gurieff

"The Phu Kham Cu-Au mine in Laos is owned and operated by Phu Bia Mining Limited. The deposit is a complex and low grade Cu-Au porphyry ore. The rougher feed has a particle size distribution of 80% passing 110 µm, and the rougher concentrate is reground for cleaning to 80% passing 25 µm. The Cu losses in the cleaning circuit are primarily in the <12 µm fraction. A randomised paired ON-OFF test of magnetic conditioning in one of the two parallel cleaner 1 circuits was undertaken. The results showed that with magnetic conditioning there was approximately a 10% reduction in the <12 µm Cu distribution in the cleaner 1 tail to a 98% level of confidence. The Cu distribution in the <12µm fraction is a less variable measure of changes in the <12µm Cu recovery, therefore, this was used to evaluate the impact of magnetic conditioning. Subsequently, magnetic conditioning was installed in both cleaner 1 circuits and the plant results monitored after this installation. Comparing the plant results immediately before and after this installation showed that there was a 20% reduction in <12µm Cu losses to the cleaner tail. INTRODUCTION The Cu-Au, Phu Kham Mine (PKM) is located within PanAust's Phu Bia Mining Contract Area in Laos, approximately 140 kilometres from the capital city, Vientiane. PKM is PanAust's flagship operation and the significant cash flow generated by PKM has supported PanAust’s growth, while contributing to a strong balance sheet. PKM comprises an open-pit mine and a conventional milling and flotation operation that produces and exports a Cu and precious metals concentrate. The concentrate contains around 23% Cu, 6 ppm Au and up to 35 ppm silver. Process Overview The PKM deposit consists of complex heterogeneous mineralogy horizons of Cu-Au stockwork and skarn mineralisation. It contains areas of soft-leached zones, overlying transition zones and supergene chalcocite dominant secondary Cu mineralisation and clay-rich gangue. Areas of high As and Zn also pose a challenge in treating the highly variable ore. In addition, hardness of the ore increases with deposit depth. The ROM is hauled to a primary gyratory crusher to produce a coarse ore stockpile with size distribution suitable for the 13 MW semi-autogenous mill. The SAG product feeds two parallel ball mills each equipped with a cyclone cluster producing a product particle size distribution of 80% passing 110 µm. The conventional flotation circuit consists of two parallel rougher banks. The rougher concentrates feed the regrind cyclone where the underflow is split and reports to two parallel, 3MW, M10000 IsaMills. The regrind mill discharge combines with the regrind cyclone overflow with a product particle size distribution 80% passing 25 µm and reports to the Jameson cell."

Jan 1, 2018

By Liming Yuan, Isaac Zlochower, RICHARD THOMAS, Thomas H. Dubaniewicz, Teresa Barone

Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane (CH4)-air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway. Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) measured thermal-runaway pressures of lithium iron phosphate (LFP) cells as a function of free space within sealed enclosures and observed an inverse power relationship. A well-confined cell produced 4260 psia (294 bar) of pressure during a thermal runaway, far exceeding minimum pressure containment specifications for conventional explosion-proof enclosures. Results indicate that adding enough free space surrounding LFP cells can reduce thermal-runaway pressures to levels below that expected for CH4-air ignitions. Measured thermal-runaway temperatures were below the minimum autoignition temperature of CH4-air.

By H. Colijn

The ever increasing price of bulk commodities forces buyers and sellers in world markets to take a more careful look at methods for obtain¬ing accurate accounting of commodity trans¬actions in commerce and material utilization in processes. Depending upon the application of a sampling and weighing system or the use intended, inaccuracies can result in an eco¬nomic loss of income or a loss in quality of the process. It inevitably results in a loss of control of ones costs. The accuracy of samp¬ling and weighing systems is today extremely important, as they are recognized to be the key components of the overall management system designed to provide both quantitative and qualitative control. This paper will be confined to the weighing systems only and will deal with various as¬pects of system design, calibration and opera¬tions. Special emphasis will be placed on new developments and requirements in this field.

Jan 1, 1988

By Jonathan Ludlow, Robert A. Jankowksi

Introduction A longwall operator can make few changes to increase output, significantly reduce respirable dust, and decrease power consumption. Reducing drum speed, and thereby cutting with increased pick penetration, is one. This article defines the benefits of deep cutting in terms of reduced dust production and power consumption. It also identifies the practical aspects of high pick penetration in terms of shearer performance and coal loading. Before examining some practical aspects of reducing drum speed and looking at the theoretical background, it is worthwhile to summarize what is meant by high penetration and deep cutting, and what potential benefits and pitfalls may be expected. Deep cutting (in the sense of high penetration rather than wide web) can be defined in one or more of the following ways: • Cutting with an average pick penetration distance higher than that used in the past. • Cutting with a pick penetration higher than the longwall operator would have used if the advantages of deep and slow cutting were not considered. • Cutting with a well-designed shearer drum below 40 rpm. All these definitions are slightly arbitrary. They are given to provide a basis for discussion and to make the point that any move towards deeper, more efficient cutting can result in operational benefits. The benefits of deep cutting appear in many different areas. The most noticeable benefit, provided suitable instruments are available, is the reduction of airborne respirable dust. During an experiment on a longwall in the Pittsburgh seam, a nearly four to one reduction in dust levels was seen when drum speed was halved. Not all studies have shown such a big reduction, but it seems that some benefit is almost always obtained when drum speed is reduced. Production rate and specific power consumption are also affected (in a positive sense) by reducing drum speed or increasing pick penetration. Although these changes may not be as spectacular as those in dust level, they contribute to the economic return of the longwall operation. Similarly, improved washability through fines reduction may have a beneficial economic effect. Cutting with shearer drums operating at lower speeds does have some possible deleterious impacts that an operator should be aware of. For example, cutting reactions - loads imposed on the picks by the coal being cut - will be increased as a deeper cut is used. Steps must, therefore, be taken to ensure the stability of the shearer and provide an adequate haulage effort. These increased cutting reactions also result in higher loads on the power transmission system (gearboxes, ranging arms, pick boxes, etc.) from the shearer motor(s) to the pick tip. These higher loads must be anticipated and provided for with the necessary hardware. In particular, extra haulage power must be provided with low drum speeds, since haulage effort required increases roughly in proportion with pick penetration. Because the drum will be rotating more slowly or will have fewer picks, the load on shearer components will also be more variable. If suitable, robust equipment is not used, this increased vibration will decrease reliability. Benefits of Deep Cutting Lower dust levels, decreased specific power consumption, and improved product washability are the most noticeable benefits of reduced drum speeds. Although the benefits will vary greatly with mining conditions and the type of coal, some examples of what can be expected are described below. Reduced Dust Levels Figure 1 shows principal results of a study on the effects of reduced drum speed conducted on a longwall in the Pittsburgh seam (Ludlow, 1981). This figure shows that average dust production was reduced by about 70% when drum speed was halved. By making some assumptions about such quantities as coal density, it is possible to apply this proportional reduction to the quantity of respirable dust liberated per ton of coal mined. When this is done, two kinds of results are obtained: • At 70 rpm, about 1 g (15 gr) of airborne respirable dust is created for every ton mined (roughly one part per million). At 35 rpm, only 0.28-0.37 g/t (3.9-5.1 gr per st) of coal mined become airborne respirable dust. • At 35 rpm, nearly four times the amount of coal may be mined before the compliance level is exceeded, compared with 70 rpm.

Jan 3, 1984

By Ryan Lindmark, Guoxing Gu, Zhenghe Xu, Jacob H. Masllyah

Induction time is often referred to the time required to form a stable three-phase contact between a gas bubble and a flat or droplet surface in a liquid medium. It can be used to quantify the attachment process in aflotation system. Various techniques have been developed to measure this important parameter. Due to its importance in flotation systems and other processes, significant advances in refining the induction time measurement techniques have recently been made. This paper summarizes these recent advances and describes a novel method developed to monitor bubble attachment to a pendant bitumen drop or bitumen-coated flat surface. This visualization-based method offers a higher sensitivity and accuracy than the previously developed apparatuses in the induction time measurement. As an example, the induction time for oxygen bubble-bitumen attachment was measured at a fixed bubble size as a function of temperature in two different aqueous solutions. The results showed that higher process temperature is favorable for oxygen bubble-bitumen attachment and hence bitumen flotation. Addition of calcium to the aqueous solution slightly decreased induction time.

Jan 1, 2005

By Andrew W. Jenike

There used to be a time when bins were designed for total volume and placed in any available place of the plant. Poke holes were provided and feed was maintained by manual prodding, lancing, hammering, and by various mechanical flow-profiting devices. Little thought was given to what occurred inside the bins and why materials did not flow. Indeed, such mental effort was hard to justify while low-cost manual labor was plentiful, quality standards low, and rates of feed moderate. The past fifteen years have seen a drastic change in these conditions. We all know that labor for hard manual work is becoming unavailable at any wage, level. Standards of product uniformity are continuously rising. This uniformity is just as important in a fine ore feed to ball mills as it is in a cattle feed or in a flour mix. Rates of feed now frequently exceed 2,000 tons per hour per feeder. At that rate there is no time for, lancing or prodding. An efficient storage, plant contains a known available volume of bulk solid, and feeds it at the required time, at the prescribed rate, and without degradation of the product. A storage bin may also perform other functions such as blending of different grades, degasification of aerated, powders, isolation of different gaseous media. A contact bed of particles flowing by gravity in counter-current with a gas or liquid may be used as a continuous reactor. Gas or liquid pressures can be simply contained by, a sufficient head of flowing solid.

Jan 1, 1968

By William R. Nash

Introduction As ore grades decline and deposit depths increase, problems and costs of mining construction increase rapidly. Ground water greatly impacts the cost of mining construction. In developing or exploiting ore bodies or coal mines, stored ground water in waterbearing formations is often encountered. Man-made conduits or shafts are constructed, as are raise bores for ventilation (up to 6-m-diam or 20-ft-diam), or smaller diameter drill holes, used for either power cables or rock dust. In underground construction and mining, it is possible to inherit unmapped and abandoned drill holes either from oil or gas exploration, or from previous geological investigations. There also exists within underground work exposure to faults, fissures, and jointing. A mine development may encounter unknown aquifers or, unluckily, have an ore body that is an aquifer. Water may invade an existing underground structure, due to concrete deterioration or to damage that may occur to an existing shaft or tunnel concrete lining. An underground development may intersect a drill hole that was not properly grouted when abandoned. It subsequently formed a conduit or an active path to conduct water into the mine. Water inflow may range from insignificant to a magnitude sufficient to inundate an area or an entire underground development. Corrosion imposes major costs. In shafts, it can cause accelerated wear and deterioration, and subsequent early replacement of hoisting ropes. It can also cause deterioration, misalignment, and subsequent accelerated wear and replacement of timber and steel guides and buntons. Utility maintenance (power cables, air, water, and ventilation lines) also can become a problem. Corrosion imposes major costs. Skips and skiploaders provide a never-ending series of maintenance headaches when exposed to an ingress of water. Numerous problems are found in declines with invert and rail maintenance and with partitions in over-under coal mine slopes. Ground water interacting with an underground ventilation system can result in: • Increased ventilation resistance due to roof falls and the spalling of ribs caused by ice heaving. • Restriction in shaft or slope cross-sectional area due to ice buildup during winter months. This may be a safety hazard to access as well. • An increase in the moisture content entering the ventilation air that condenses underground and causes electrical and equipment maintenance problems. Underground structures also incur water-caused problems. The concrete lining in shafts, slopes, and tunnels may be subject to: • Active mine waters causing concrete and reinforcing steel to deteriorate - perhaps to the point of collapse. • Load redistribution around a concrete lining, caused by soil dislocation due to water movement. The resulting stress may be in excess of the calculated design loading. Backwall injection with grout of the completed concrete lining may solve these water inflow problems through low-pressure injections of cement and chemicals. This fills voids at the interface of the concrete lining with either the soil or rock excavation. Surface structures may be jeopardized by lowering the ground water table, resulting in surface settlements. Surface settlements can occur in buildings, headframes, hoist foundations, mills, conveyor structures, or in rail haulage. Areas of differential settlement can lead to derailments, improper wear of hoisting ropes on sheaves in headframes, and the misalignment of bearings and brakes. Mud jacking and compaction grouting may remedy these problems. To reduce operating costs, increase efficiency, and increase safety, inflow water to the mine should be minimized. For an operating mine with a water problem, a water inflow survey should be taken. Quantities of water flow should be examined at all accesses (shafts, slopes, bore holes, and raise bores) at the faces, haulages (rails or conveyors), and sump discharge. From this examination and quantity survey before and after heavy rainfalls, valuable data for elim-

Jan 3, 1984

By John A. L. Campbell

Surface dependent processes, such as froth flotation and flocculation, are important or potentially important techniques for combating some of the current major problems in coal preparation. In order to correctly apply or imporve a surface dependent process, it is of paramount importance to understand the interfacial phenomenon, especially the double layer properties, exhibited by the solid. The specific objective of this research was to determine the properties of the bituminous coal/liquid interface by an electrokinetic method, streaming potential, and to relate the findings, wherever possible, to the existing unit operations of froth flotation and flocculation. The electrokinetic properties of both the whole coal and its lithotypes were investigated. As part of the total investigation, the role played in the double layer by the reagents commonly employed in the surface dependent process was also established (1). These data will be presented at a latter date.

Jan 1, 1969

By J. Maiti, A. Bhattacherjee

A literature review on quantitative analysis of mine safely studies revealed that numerous investigators explored a wide- range of techniques, including the investigation of bivariate and multivariate statistical models. Although these researchers addressed various issues of accident causation and prevention, they, in general, did not investigate through the use of quantitative models the multivariate relationships of several factors affecting mine safety in a causal framework. In this paper, systems dynamics and structural equation modeling are presented to simultaneously represent and study the effect of policy variables related to accident prevention along with the factors causing accidents and injuries. The application of these models to a group of mines revealed that current training practices at these mines do not appear to alleviate accident occurrences. It is inferred that the use of these quantitative techniques can provide a new direction of research in mine-safety studies.

Jan 1, 2000

By F. Dudouit, M. M. Mohkam, F. Renault

The Pannerdensch Kanaal Tunnel is part of Holland’s Betuweroute high speed freight railway project linking Rotterdam to inland of Europe. It comprises of twin tunnels, 1620 m long each, with 8.6 m inner diameter. The Tunnel alignment is situated mainly in sandy formations and under high hydrostatique pressure. The over burden cover varies from relatively high to very low, sometimes much smaller than the diameter. One of the special features of the Pannerdensch Kanaal Tunnel is that, over some 250 m, the twin tunnels are to be bored in a back?lled sandpit. Some 490 000cubic meter of sand has been placed and compacted by vibro-?otation to refill the sandpit. The tunneling machine is a 9.8 m slurry shield manufactured by Herrenknecht. Tunnel lining is precast concrete consisting of seven plus one key universal segments. Other than the special feature of boring through re?lled sand, constraints such a slow overburden while crossing under Pannerdensch Kanaal and some lagoons, as well as high liquifaction potential of sandy formations, render this job very unique of the type. Fine studies were conducted in heading’s stability. And, confinement pressures were determined considering different risks of liquefaction and blowout problems. Both tubes have been successfully bored. Several sections have been monitored. The results are quite interesting and in accordance with contract technical conditions.

Jan 1, 2003

By Z. T. Bieniawski

After many significant advances in mining including development of sophisticated methods for strata characterization and numerical modeling analyses, the engineering design process in mining is as primitive as it was two decades ago. Yet, major advances in design methodologies have occurred in other branches of engineering. Is creative design in mining a myth only? Are we deluding ourselves when we talk about innovative mining design of today? What is the reality of the situation? This paper explores the methodology of creative engineering design as a new recognized discipline. It warrants applications in mining since design experts are sometimes unaware of their own decision-making processes.

Jan 1, 1988

By H. Nematollahi

Numerous magnesite deposits are found in the south part of Khorasan state, east of Iran. During the past few years, production of high-grade magnesite ore was possible only by using selective mining method. The decreases of high-grade ore imply upgrading of the low-grade ore. To do so, the objective for the first phase is to obtain a material which contains less than 2.5% SiO2. The present study was carried out based on three different samples. The results obtained in laboratory indicate that the direct flotation of magnesite by fatty acids led to acceptable result.

Jan 1, 2003