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By Frank F. Aplan, Edward C. Jr. Dowling, Richard R. Klimpel

Thirteen kinetic models that mathematically describe the flotation process have been statistically evaluated for the flotation of copper, lead and zinc ores. Comparisons have been made for a variety of circuits involving roughing, cleaning, scavenging and regrind followed by cleaning. Variations in collectors, frothers, depressants and activators have been considered. Based on the statistical criteria used for the evaluation, and the reagent, circuit and ore variations studied, the most reliable flotation models have been identified and subsequently used to characterize the metallurgical results.

Jan 1, 1986

By Rudolf E. Pfister

One of the Swiss transalpine highways includes two remarkable tunnels: the 16.3 km long Gotthard Road Tunnel and the 9.3 km long twin tube Seelisberg Tunnel, both presently under construction. Large diameter shafts up to 900 m long are required for ventilation. Excavation techniques for rock formations ranging from loose sedimentary rock to granite and very hard siliceous limestone were carefully evaluated. The methods finally applied include excavation of shafts in hard rock, conventional drilling and blasting, excavation by ripper-tooth excavator ("Big John") in marlstone, shield protected heading in loose material and soft rock, and tunnel and shaft lining, both by poured concrete and by prefabricated elements. A critical review of the success of these methods can now be made after a five year construction period.

Jan 1, 1976

By S. Tuylu, D. Adiguzel, U. G. Akkaya, A. Bascetin

"One of the main problems for storing of the tailings is acidity occurrence due to several factors such as existence of sulfuric minerals and also the pollution in seepage waters by mobilization of metal ions, which holds great risks in terms of environmental regulations. Because of these specified reasons, tailing materials to be used in a SPD formula should have comply with some specifications. Among these properties; oxygen content, temperature, matrix suction and pH are the most important parameters. In the study, the relationships between the parameters mentioned are investigated to reveal optimum paste design layout. The lowest amount of seepage water obtained from the paste layers in the pilot cabinet was found as 2150 ml from 3rd layer. As for the maximum seepage water and the average of the all 11 layers were found as 4909 ml from 6th layer and 3273 ml respectively. The reactions occurring according to the oxidation, as seen at seepage water of second and third layers, decreased the pH of system to the under of 7 value. Additionally, when the seepage water of first layer’s EC value is 2.93 mS/cm, the EC value of second layer is increased at 3.54 mS/cm. The other parameters are evaluated with the obtained results of the tests to determine the optimum storing conditions for SPD.INTRODUCTION Conventional waste disposal methods, although widely used, pose great environmental risks. One of the most important issues is acid mine drainage (AMD). Tailings of metallic mines contain heavy metals, aggressive chemicals and hazardous materials. In the presence of oxygen and water, an oxidation reaction can occur, causing a decrease in pH of the environment, and heavy metals that are present in the environment can dissolve easily. Subsequently, heavy metals can pollute underground water basins, creating a great amount of danger for the ecology and potable water resources. Another important risk associated with conventional waste disposal methods is accidents related to the waste dam. Higher volumes of water and tailings (usually 15% solids and 85% water by weight) are sent to waste dams, making it very difficult to control the stability of the dam under conditions such as static and dynamic loads (seismic activities, vibrations caused by blasting, etc.), flooding, and seepage. In case of an accident or failure, the spread of great amounts of mud containing hazardous chemicals and heavy metals can harm the environment of the dam site significantly (Bascetin et al., 2014). In the paste technology, depending on the type of ore, tailings used in the paste mixture can contain sulphide minerals (such as pyrite and pyrrhotite). These minerals are known to be reactive with water and oxygen to produce acidity (sulphuric acid)."

Jan 1, 2015

By Christopher J. Bise

INTRODUCTION Face haulage in underground mines and pit haulage in surface mines are the principal domains of rubber- tired haulage vehicles. In underground mines, cable- reeled or battery-operated shuttle cars and diesel-powered load-haul-dump vehicles are used; trucks are primarily used in surface mines. Although many concerns go into the selection of rubber-tired haulage vehicles, such as clearance and tire life, the most important factor from a mine-planning standpoint is the production capability of the vehicle in the mine environment. Therefore, this chapter will address this topic. UNDERGROUND FACE-HAULAGE VEHICLES The selection process for underground face-haulage vehicles is, in some respects, much simpler than that of the other haulage systems discussed to this point. It is simpler because these vehicles, which transfer the mined material from the face to the intermediate haul¬age system, are manufactured in various size ranges to cope with the confinement of underground opening widths and heights. However, since these vehicles oper¬ated in an intermittent fashion in conjunction with a constantly advancing face, the system's lack of perma¬nence and overall dynamic nature create a more diffi¬cult situation for predicting productivity. The emphasis in this section will be on prediction of productivity. There are three fundamental steps that must be taken to analyze the productivity potential of any face¬haulage system: l) Recognize the geologic (seam thickness, etc. ) and mining (opening widths, etc.) constraints that affect the velocity/clearance aspects of the haulage equipment, and select equipment from manufacturers' specifications with these con¬straints in mind. 2) Secure the elemental times of the face-haulage system. 3) Incorporate the elemental times into an accepta¬ble mine plan. By recognizing the geologic and mining constraints that affect the system layout, parameters, such as vehi¬cle payload, tonnage to be hauled per cut, and haulage distances, can easily be determined. Elemental times can be developed in two ways: 1) In an existing operation, a time study of the dynamic system can be conducted by placing three time-study engineers at the following static locations; (1) near the loading machine, (2) near the change-out point outby the face, and (3) near the dump. By synchronizing their watches and recording the actions of the haulage vehicles at these three locations, their time studies can be reduced to provide elemental times, such as vehicle tram rates (empty or loaded), vehicle discharge times, and loading rates. 2) In the absence of an existing operation, average values for the elemental times can be provided from other mines operating in similar condi¬tions, or by the manufacturers themselves.

Jan 1, 1986

By M. C. Baumann

The Getchell Mine is located in Humboldt County, Nevada, approximately 70 km northeast of Winnemucca. Slope management has been a critical factor in the feasibility of mining operations since they began in the early 1930's. Although underground entries began in 1937, underground production was limited because hanging walls consisting of clay gouge and crushed rock tended to collapse into the workings. Controlling these collapses required extensive timbering. Due to these poor ground conditions, surface open-pit mining was the primary mode of production from 1938 to 1967 with only minor contributions from underground operations. Mining was suspended in 1967 due to economic pressures. From 1960 to 1967, the previous operator mined the property in three open pits. Initially, these pits were constructed with footwall benches, but these failed. These failures were aggravated by construction of 60° slopes in footwalls with shale partings dipping into the pit at 43° to 60°, resulting in large planar failures and wedge failures. In response, the previous operator adopted a slope parallel to the bedding planes.

Jan 1, 1993

By Theodore Triplett

To assess the value of various subsidence mitigation techniques, twelve linear foundations were constructed above a longwall mine. The structures were monitored during and after undermining, and footing curvatures at the time of cracking were compared with predicted values. An unreinforced concrete footing sustained substantial damage. Other footings received varying degrees of damage, with inclusion of a sand layer significantly affecting performance. A post-tensioned concrete foundation suffered minimal cracking. Also, a technique developed by the Bureau of Mines is presented for determining the subsidence, slope, curvature and strain of the ground surface.

Jan 1, 1986

By J. Bartrum

Kidston Gold Mines is a 14 000 tonnes per day rated operation located 280 kilometers west of Townsville in Queensland. The principle shareholder is Placer Development Limited. Kidston's orebody consists of 44.2 million tonnes graded at 1.79 g/t gold and 2.22 g/t silver. Production commenced in January, 1985, and despite a number of control, mechanical and electrical problems, each month has seen a steady improvement in plant performance to a current level of over ninety percent rated capacity.

Jan 1, 1985

By D. A. Rice

In pelletizing magnetic iron ore concentrates, about 6 to 18 lb of bentonite binder are added per ton of concentrate during balling to give green and dry strengths to the unfired pellets. The dry bentonite is mixed into the filtercake following the magnetic concentration circuit of the plant. The filtercake contains about 10% moisture, and the water may be of highly variable composition, depending on the particular concentration circuit, its source, and the ore being treated. A knowledge of the parameters that influence the balling operation is essential for optimal efficiency in producing balls strong enough to survive the treatment during transportation from the balling device to the furnace and during the firing operation. Furthermore, very weak unfired pellets probably contribute to high dust losses and poor furnace control. The factors that determine the strength of unfired pellets have received considerable study (1,2,3,4). Tigerschiold and Ilmoni(l) pointed out the significance of the surface area of the particles being pelletized. Merklin and Childs(2) reported on the effect of material size consist, chemical additives such as soda ash, lime, balling time, ball size, and the moisture content of green balls. Iwasaki and Zetterstrom(3) examined the detrimental effects of fatty acids on the pelletizing process. Stone(4) correlated the zeta potential of bentonites with the strength of unfired pellets. He found that, in general, a high negative charge on the bentonite is conducive to good balling. Although studies of pelletizing in the iron ore industry deal with a complex multicomponent system consisting mainly of the iron mineral, bentonite, and water, the last of these has received little attention, particularly with regard to the possible effects of mill water chemistry on the pelletizing process and the strength of unfired pellets. It is widely known that the composition of mill process water is an important variable in unit operations such as flotation, thickening, and filtering and that impure water can lead to poor metallurgical results. The results of the present study indicate that the chemistry of the mill water may be an important variable in the balling operation as well. Knowledge about this variable should contribute to lowering bentonite and oil consumption and to improving furnace performance. Such knowledge can also assist those who use balling in evaluating commercial bentonites for plant use as well as those investigating balling from a more fundamental point of view In this study we have examined 1) the effects of replacing mill process water in the magnetic concentrate filtercake with pure water, and 2) the effects of several chemical impurities that are commonly found in mill process waters upon the strength of unfired pellets. The results are interpreted in terms of the zeta potential of the bentonite and magnetite particles. The data lend support to a suggested mechanism whereby the electrostatic attraction of oppositely charged particle surfaces causes bentonite-bentonite and magnetite-bentonite bonding. This mechanism would also explain why several chemical additives e.g., sodium carbonates and phosphates, have such marked effects on increasing the strength of unfired pellets.

Jan 1, 1971

By Robert E. Ennis

Several important economic variables must be studied when planning a major underground conveyor haulage system if the objective of tow cost haulage is to be met. The purpose of this paper is to call these economic factors to the attention of the mine planner and encourage their serious consideration. To illustrate, the importance that some of these variables hole for the mine operator who wishes to reduce costs and maintain sound belt haulage practice, these areas of discussion will be covered. 1. Selection of economical flite lengths. 2. Economics of wire rope frame vs. rigid frame conveyors. 3. How idler design affects conveyor costs. 4. Economies in drive design. 5. How speed affects conveyor cost. 6. P.V.C. vs. Neoprene belt - what savings? 7. Maintaining, conveyor investment through maintenance. 8. Miscellaneous factors affecting the cost of belt haulage.

Jan 1, 1967

By P. Hambach

Murer Company, Andermatt, Switzerland, can claim to have done pioneer work in the construction of inclined shafts. This happened in 1968/69, when we decided to bore with a Wirth tunnel borer an inclined shaft, 1100 m in length, 3.0 m in diameter, and with a grade of 65%, in the 2400 kilo pascall per sq. cm granite of the Montblanc Massive. The whole excavation was accomplished in ten months which, at least for European conditions, can be claimed as a record. It was, at least to our knowledge, the first inclined shaft to be bored full-face (Fig. 1). Encouraged by the experiences and performances attained at Châtelard, we approached other projects of the same kind. We were awarded, together with Hochtief Ltd., Essen, a contract from Schluchseewerke, Freiburg, Germany, in December 1969, for the construction of a penstock for the Hornbergstufe at Wehr, Germany, with a diameter of 6.3 m. This inclined shaft with a grade of 55% is located in Schwarzwalder granite with a compressive strength of up to 2000 kilo pascall per sq. cm, about 31,000 psi. As no exact geological data were available about the rock to be worked, and a fault zone from 80 to 150 m long had to be faced, as well as a few individual fissures of varying thickness, it was decided to use the multi-stage method. The 3-m diam tunnelling machine which had driven the oblique shaft at Châtelard had now finished work, and an immediate beginning was made with driving the pilot staft. This was very welcome to the contractor, since exact information about the type of rock present and the inflows of water was required immediately and before the final borehole diameter was fixed, for the purpose of dimensioning the supports to be subsequently installed.

Jan 1, 1974

By F. Wolf, R. Ellmies

"Fluorspar is one of the most important industrial minerals. It has a wide range of applications, for example it is used in the steel and aluminum industry, and is also the raw material to produce hydrofluoric acid, Teflon or Gore-Tex. There are only a few major fluorspar mines worldwide, with China being the most important fluorspar producer (U.S. Geological Survey National Minerals Information Center, 2017). At Okorusu, Namibia, fluorspar has been mined with conventional open pit mining methods from 1955 until 2014 from a large scale metasomatic fluorspar deposit with seven identified orebodies. There are about 7 million tons of measured resources left with an average grade of 27.5 % CaF2. This paper is based at an MSc thesis at Technical University Freiberg and describes the design of an underground mine for the A and D orebodies with an annual production rate of 100,000 t acid-grade fluorspar product. By comparing different mining methods and adapting variants of access to the underground orebodies the paper will emphasize on the selection of a suitable mining technology, with a special focus on the economic considerations to decide about the most profitable operation. INTRODUCTION Mining holds an important part in the economy of Namibia. In 2016 11.1 % of the GDP was made through mining activities with 22 active mines (The Chamber of Mines of Namibia, 2016). Only one of them consists an underground mining operation. The global annual production of fluorspar is approximately 6 to 7 million t (U.S. Geological Survey National Minerals Information Center, 2017). Okorusu produced on average about 50.000 t annually in recent years (U.S. Geological Survey National Minerals In-formation Center, 2015). Okorusu Mine is Namibia’s only fluorspar mine. Fluorspar was mined in an open pit mine with four individual pits (A-D) since 1980. In 2014 the mine closed due to the increased stripping ratio and beneficiation problems. The mine assets were bought by Gecko Namibia. Currently Gecko uses parts of the processing plant for beneficiation of graphite from a neighboring mine. Figure 1 shows a panoramic view with the four pits and the mine village. The intent is to develop a concept for the further underground development of the mine. There are still about 7 million t of measured resources left in the deposit, with an average grade of 27.5 % CaF2. This study focusses on the underground mine design. The above-ground plant and facilities are considered as remaining unchanged."

Jan 1, 2018

By Sathit Tandanand

Geological differences among various coalfields restrain the applicability of subsidence prediction using existing European methods. To modify these methods for domestic conditions, the Bureau of Mines, U.S. Department of the Interior, developed a method of assessment to evaluate the lithological effects on subsidence in the Northern Appalachian basin by examining data collected from 16 longwall panels in the coalfield. The assessment is partially completed, and the results to date show that the ratio of maximum subsidence to the extraction thickness, known as the subsidence factor, can be expressed in terms of the width-to-depth ratio by a simple exponential equation which has a coefficient tentatively considered as the subsidence index. This index varies with the lithology of a particular site and can be expressed in terms of the percent distribution of weak and strong rocks in the overburden.

Jan 1, 1982

By R. J. Mirville

Flocculation is an important step in the treatment of coal preparation waste waters. The effects of polymer charge and molecular weight and solution pH and ionic strength on the adsorption and flocculation characteristics of a series of polymeric flocculants on some typical waste water constituents have been studied experimentally. The results indicate that the nature and extent of flocculation are strongly system-dependent. For the case of coal, both adsorption and flocculation behavior can be correlated with the polymer conformation in solution. For the mineral constituents, on the other hand, adsorption and flocculation depend also on the surface properties of the solid.

Jan 1, 1979

By D. Malhotra

Metallurgists are continuously striving to improve recovery. But optimization of profits and/or revenue dictates that recovery can be sacrificed at the expense of throughput. However, recently there has been significant interest in the concept of retreatment of tailings to enhance recovery and hence revenue while maintaining high throughput. The authors discuss the technical and economic factors that need to be considered in evaluation of the feasibility of retreatment of tailings including the potential feed streams (i.e., rougher tailings, cleaner tailings, etc.) and processing options (i.e., physical beneficiation, chemical processing, etc.). A case study for base metals is discussed.

Jan 1, 1994

By E. Woodburn, Harrison R. Cooper, R. Putman

The key to concentrator automation is practical means for obtaining continuous assay data from concentrator streams. The technique most successfully used is x-ray fluorescence analysis. The practical reality of on-stream x-ray analysis has been achieved through effort over the past twenty years, marked by an occasional breakthrough, but more typically a step-by-step development to which many individuals and organizations have contributed. The net result of this progress is the present capability to install on-stream x-ray analyzer systems on a turn-key basis. It is now possible to provide all components of an x-ray analysis system as a completely engineered unit which can be put into immediate use, minimizing needs for specialized application know- ledge to benefit from continuous assaying in process control. The economic factors which influence the choice of system and limitations of the x-ray fluorescence technique for slurry analysis are reviewed.

Jan 1, 1976

By J. J. Schwoebel, M. J. Mavor

Rapid coal extraction techniques in gassy mines may strain a ventilation system if a degasification approach is not utilized. Design of mine ventilation systems requires estimates of gas emission rates from unmined coal into the existing mine workings. A degasification system for a specific property can be properly engineered to improve mining economics if the proper geologic and reservoir information is collected. This paper describes methods to determine the degasification rates for horizontal boreholes and vertical (stimulated and unstimulated) wells and the rate of gas emissions into the mine workings. The methodology is demonstrated by a specific example. Horizontal boreholes drilled in advance of mining are demonstrated to be the most effective means of coal seam degasification and reduction of gas emissions into mine workings. The significance of the paper is that few published methods for these estimates are available

Jan 1, 1991

By K. Zabrusky

Epithermal vein systems are often modeled as simple, discrete high grade structures within low grade host rock. However, geologic setting and structural preparation influence how such vein systems form. In structurally complex areas, veins may follow several structural trends and occur on a variety of scales. Geologic and grade modeling within such complex structural regimes can be difficult as individual veins cannot be delineated from host rock based on grade alone. Structurally complex areas require a different approach than traditional discrete vein modeling. Presented herein is a study of a structurally complex area that hosts vein mineralization to be mined underground. All veins could not be modeled discretely, so an alternate approach was needed. Major structures were modeled using surface and underground mapping and were then used to create a structural trend for the area. This trend was used to guide 3D grade shell construction. The grade shells replaced 3D vein solids for grade estimation in order to mitigate the influence of high grade samples. Structurally guided grade shell construction offers a more effective modeling method than discrete vein modeling in deposits that are structurally complex.

Feb 23, 2014

By Gordon T. Clark, Stephen H. Gleaton

This paper discusses the conceptual design of cut-and-cover tunnels currently being considered as one of the replacement options for the earthquake damaged, elevated double-deck highway and seawall built in downtown Seattle 50 years ago. The 4.8 km (3 mile) long, 6-lane improvement consists of 1.6 km (1 mile) of at-grade roadway with aerial interchanges, 1.6 km (1 mile) of large two-level cut-and-cover tunnels along the Elliott Bay waterfront, and retrofit of the 50-year old, 1.6 km (1 mile)long Battery Street tunnel and north transition to grade. Construction of deep cut-and-cover tunnels, in complex glacial geology overlain by hydraulically placed fill immediately adjacent the existing sea wall, will require extensive use of concrete diaphragm walls, ground improvement and dewatering. The potential liquefaction and lateral spreading of the fill materials in this active seismic region pose significant design challenges and risk.

Jan 1, 2003

By P. Soupios

Seismic geophysical methods have long been used by geologists and geophysicists to delineate subsurface features. These techniques work because different types and strengths of soil and rock transmit energy at different velocities. The Crosshole-Downhole tests (CH-DH) and seismic refraction survey (RS) are among the most used methods in engineering applications to obtain the elastic properties of subsurface layers. As a result, seismic methods have evolved into a cost-effective tool for rapidly determining depth to bedrock in engineering and construction projects. The seismic methods are best suited to sediment thickness analysis, bedrock quality determination and detection of the presence of weaknesses in the bedrock before the erection of any civil engineering structures such as bridges, tunnels, dams and portals. Seismic methods are also useful in estimating the rippability of bedrock ahead of construction. These methods are particularly useful for large-scale projects that require a significant number of drill holes, resulting in a substantial investment of time and costs for drilling. The CH-DH and RS methods are typically comparable in total cost to drilling, but provide significantly more information in 2-D and 3-D and therefore reduce the likelihood of conceptually oversimplifying the subsurface conditions. The above mentioned methodologies were considered to be the most appropriate geophysical methods for investigating the shallow structure and the dynamic soil properties of the area where the Ilarionas Dam is scheduled to be constructed. The main target of this work was to prove the potential of geophysical methods in providing accurate information to the civil engineer and to obtain information on the dynamic soil and rock properties for earthquake design analyses for the dam construction. Specifically, nine refraction seismic profiles and three cross-hole-downhole seismic tests were implemented to determine the subsurface conditions of the study area. The tests determined the shear and compression wave velocity profiles versus depth and other crucial parameters such as Young and Rigidity modules. Furthermore, they allowed the detailed 2-D mapping (along several profiles of the study area) of the subsurface variation of the soil and rock dynamic moduli.

Jan 1, 2006

By C. J. B. Dreyer, H. A. Robinson

Only South Africa can be considered in terms of resources of amphibole asbestos. There are two asbestos producing fields, one in the Northern Cape Province (producing only crocidolite), and one in the Eastern Transvaal (producing only amosite). This chapter discusses the banded ironstone sequence in which amphibole asbestos occurs, and the genesis of the fiber is briefly reviewed. Also, the properties and characteristics of amphibole asbestos are discussed and compared to those of chrysotile. Approximately 300 000 t of arnosite and crocidolite are produced annually. Crocidolite has a potential for a fivefold increase of production chat could be sustained beyond the year 2000. An estimate of the resources of the various producing fields in South Africa is made. The mining methods are also reviewed and evaluation techniques are discussed. The only two types of amphibole asbestos exploited at present in South Africa are amosite [the white colored amphibole asbestos) and crocidolite (the blue colored asbestos). As is well known, crocidolite has been mined in South Africa from the early part of this century, and amosite since the early 1930's. Since these dates, asbestos mining has developed into a significant mining industry. The annual production of crocidolite is approximately 170 000 to 200 000 t. and amosite production is in the region of 80 000 to 100 000 t. CLASSIFICATION OF AMPHIBOLE ASBESTOS Four types of amphibole asbestos are produced economically in the world today: (1) crocidolite, the fibrous equivalent of riebeckite, (2) arnosite, the fibrous equivalent of grunerite, (3) trernolite, and (4) anthophylite. The names trernolite and grunerite apply equally to the crystal and fibrous forms of these minerals. For comparison and clarification purposes, the six known varieties of asbestiform minerals known in the world are shown in Table 1. All the asbestos minerals were originally developed as cross fiber seams in veins or fractures, or were controlled by the lithology. Post- fiber effects caused slip, sheared, and folded fiber seams. Crocidolite and amosite occur in banded ironstone of early Proterozoic age of the Transvaal Supergroup. The fiber seams are developed in certain defined lithological units in the banded ironstone sequence. The lithological units have a remarkable lateral persistence with respect to their chemical nature and physical appearance. Vertically, the banded ironstone sequence displays a heterogeneous nature. Commercial Applications The features and properties that make amphibole asbestos commercially attractive are: 1) The long average length of the fibers is good for greater wet strength in composites. 2) The high tensile strength of crocidolite makes it superior to all other types of asbestos. 3) It is characterized by dispersion in most liquid media, particularly amosite in water. 4) Since the surface charge of amosite and crocidolite is negative, the fibers produce an open lattice work in water with a high bulk volume giving excellent filtration rates and rapid drainage in a wet asbestos cement mix. 5) The insulating properties of amphibole asbestos mats are still important, particularly in a corrosive environment, despite the introduction of many other synthetic insulating materials. 6) Corrosion resistance, particularly acid corrosion resistance. 7) Due to the high modulus of amphibole fibers, resins reinforced with these fibers exhibit

Jan 1, 1986