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By V. Rajaram

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) imposed a no-blasting specification (blasting is restricted to the construction shaft and shaft bottom or boot) on the Deep Tunnel project in 1988. This was prompted by numerous complaints from the residents in the vicinity of the project, and controversies experienced on previous projects from blasting the rock overlying the tunnel. This paper will describe the methods utilized by two major contractors who are driving 20 km (12.5 of tunnel along with drilling over 36 shafts under this restrictive specification. The impacts on design, construction, schedule, cost, and the environment are detailed.

Jan 1, 1991

By C. O. Brawner

INTRODUCTION My first major involvement on a rock mine slope stability project was in 1966 after I had become a principal of Golder Brawner & Associates in Vancouver, Canada. I received a request from Kennecott to evaluate two serious rock slope failures adjacent to the concentrator on their British Columbia molybdenum property near Alice Arm, BC, which was under construction. A rock slope up to 200 ft* high had been excavated at a design angle of 700. The inspection indicated that several large blocks of about 1000 cu yd each had failed on steeply inclined joint surfaces. Stability was reduced by extensive seepage caused by heavy rainfall. In addition, considerable overbreak had occurred, indicating excessive blasting had been used to excavate the slope. A program was developed to rock bolt potentially unstable blocks that could slide on dipping discontinuities. Some rock was scaled back to the inclined joints, and drain holes were drilled to reduce water pressures. The project was completed successfully and within reasonable economics. As a result of this success, enquiries were received regarding other mining projects. This indicated the potential demand for rock slope engineering. As a result, I took one month off to meet and discuss rock mechanics and slope stability with various people internationally. These included D. Coates in Canada, E. Hoek in England, K. John and L. Mueller in Germany, M. Rocha in Portugal, and the US Bureau of Mines in Denver, CO. Early misconceptions Based on involvement in projects during the next few years, it was concluded that there were a considerable number of misconceptions that existed among some geologists and mining engineers dealing with surface rock mechanics. Some of these included: • Water is a lubricant. This is incorrect. Water reduces the shear strength along discontinuities due to buoyancy, which reduces frictional strength. It also reduces the cohesion of clayey-type rocks. • The optimum pit slope angle in rock is 45°. The optimum slope angle for safety and economics is variable and is influenced particularly by structural geology, water pressures, mine blasting practices, and the depth and degree of weathering. • The flattest angle for slope stability is dictated by the angle of repose of broken rock, about 370. Where clayey-type rocks or clayey infill in discontinuities exists, failure can occur at much flatter angles, requiring flatter slopes or artificial stabilization. • Uniaxial and triaxial tests provide the necessary shear strength parameters to design rock slopes. Most failures in rock slopes are controlled by directional discontinuities. Therefore, the direct shear test is the correct test to evaluate strength parameters for most problems.

Jan 1, 1987

By S. Sener

In this investigation, the changes in the grindability of both ulexite and colemanite related with the different structural modifications created by the heat treatment were examined with respect to work index (Wi). The effects of the heat treatment temperature and time on grindability index were also investigated. It was observed that, heat treatment significantly affected on the grindability of ulexite. The work index of original ulexite was found 7.11 kWh/shton and decreased to 3.5 kWh/shton level within 200-480°C for 60 minutes. On the other hand, the work index of original colemanite was found as 6.48 kWh/shton and no appreciable change was observed when heated up to 320°C. Thermally assisted comminution can be used to improve the grindability characteristics of ulexite. Besides, the different behaviour of ulexite and colemanite under heat treatment can be used for their separation. The artificial mixture of ulexite and colemanite could be separated with over 90% recovery by utilizing their different grindability characteristics by thermal treatment, semi-autogeneous grinding and screening.

Jan 1, 1999

By Michael von Seebach

High-pressure grinding rolls subject the feed material to pressures of 200 N/mm? During this process considerable size reduction and the Formation of flakes occur. This paper describes the basic consideration For design and operating of this type of mill. It is also shown that the particle size distribution resulting from this process is typical for grinding processes but untypical for crushing processes. High pressure grinding rolls are designed in size of up to 2.8 m roll diameter allowing feed material top sizes of 250 mm. The rigid frame, bearing and drive - train design allows a broad application of the high-pressure grinding rolls operating the machine in open or semi-closed and closed circuit for dry and moist feed materials. Operating results show that capacity increases of up to 100 % can be accomplished with this technology. The high-pressure grinding roll also, allows for lower operating and maintenance costs due to energy savings of up to 20 L and reduction of wear to less than 1 76 for dry and less than 0.1 5 for wet grinding. Other advantages of the high-pressure grinding rolls are smaller equipment sizes than a ball or SAG-mill for a given capacity resulting in lower building sizes with reduced capital in- vestment costs.

Jan 1, 1987

By D. E. Ranta, M. G. Hester

The ore reserve modelling of stratiform uranium deposits to be mined by selective underground mining methods must be done with consideration of the erratic nature of the ore-forming processes that produced the mineralization. Estimation methods that model the uranium grade as a smooth transition between high-grade and low-grade drill hole intercepts tend to greatly overestimate the ore tonnage. Care must be taken to first establish realtistic ore pod geometries and then estimate the grade of the reserve units within the pods.

Jan 1, 1992

By J. Zhai, Z. Yin

"The electrokinetic and flotation behaviors of ilmenite using lead ions as the activator and sodium oleate as the collector were studied. The results of microflotation show that the flotability of ilmenite can be improved by lead ions obviously. The isoelectric point of ilmenite increases from 5.32 to 7.7 after the addition of lead ions because of the adsorption of Pb2+ and Pb(OH)+. The results of zeta potential measurements and the collector adsorption density calculation show that the adsorption of sodium oleate on the ilmenite surface via chemisorptions in addition to electrostatic interactions. Besides, the adsorption density calculation results show that as the addition of lead ions as the activator, the adsorption amounts of collector are greater than those without activation which is in aggrement with the flotation behaviors. INTRODUCTION Ilmenite, as an oxide mineral of formula FeTiO3, is usually used as the main resource of the extraction of titanium (Bulatovic and Wyslouzil, 1999). There are many researches showing that the conventional methods, such as gravity separation, magnetic separation and flotation, do not work efficiently as expected (Mehdilo et al., 2015; Zhu et al., 2011). Nowadays, to produce ilmenite concentration feasibly and efficiently, these separation methods above are combined for a reason that the raw ilmenite ores are characteristic of poor, fine and complicated. Moreover, surface modification, such as surface dissolution method, microwave irradiation and oxidation roasting, is applied to improve the flotability of ilmenite currently (Welham and Llewellyn, 1998; Zhang and Ostrovski, 2002). Generally, fatty acid salts are used as the collector for the flotation of oxide minerals and sodium oleate is usually used as the collector for the flotation of imenite ores (Fuerstenau and Pradip, 2005). The mechanism, such as individual ion electrostatic adsorption, chemical adsorption, ion–molecule dimeric complex adsorption, and the coadsorption of ion and molecule, have not been discussed systematically using sodium oleate as the collector in the flotation of ilmenite (Somasundaran, 1983). Under the activation circumstance using the lead ion as the activator and sodium oleate as the collector, the interaction mechanism seems to be still unclear. In the present study, the interaction mechanism between ilmenite and sodium oleate using lead ion as the activator are studied by microflotation, zeta potential measurements and adsorption density calculation. EXPERIMENTAL Materials and reagents Pure ilmenite minerals were obtained from Panzhihua, Sichuan province, China. The minerals were ground in a porcelain mill with an agate ball. Following that, the prosucts were sieved, and the samples of -0.074+0.038 mm size fraction were used for the microflotation experiments. The results of XRF show that the content of titanium element is 30.58%, showing that the purity of ilmenite is above 90%. On the basis of the results of XRF, it is determined that the purity of ilmenite is very high and meets the needs of microflotation"

Jan 1, 2017

By R. Addison, T. Swendseid, R. Kehmeier, D. Larsen, J. Uhrie

"The development of a mining project necessarily progresses through many steps, beginning with the identification of a mineral resource and continuing through project construction. Several classifications of engineering study development are described, including preliminary economic assessment (PEA) or scoping studies, prefeasibility studies (PFS), feasibility studies (FS) and regulatory codes, each with a specific project organizational objective. This paper addresses the PEA, PFS and FS types of reports that are used by companies to evaluate projects, meet regulatory requirements and seek financing. The minimum requirements for engineering studies, focusing on the needs of financial institutions considering investment in a project, are outlined. IntroductionThe financing of mining projects in recent years has come under increased scrutiny by financial institutions owing primarily to an increasing percentage of projects whose capital expenditures had overrun project budgets or had failed to produce the economic returns anticipated during the project development process. Often, unfavorable project outcomes are not the result of widespread failures of the project engineering process but arise from inadequate engineering in limited specific areas of the project scope, such as overestimated mineral reserve, inadequate mine design, insufficient metallurgical testing or underestimated capital costs. Mill facilities and process infrastructure typically are responsible for up to 80 percent of the capital expenditures required by greenfield mining projects. They are often the project areas where capital costs are inadequately developed, and consequently are the areas highly scrutinized by financial institutions. This paper offers a perspective on the level of engineering expected by financial institutions as a prerequisite to committing support to developing mining projects.The evaluation of a mining project from exploration through development and production is a lengthy and complicated process. Mine development commitment activities for a potential project are initiated when a mineral resource is identified and continue through to the start of construction. The technical feasibility and the economic viability of each project are determined during the phases of mine development with more detailed engineering data required at each stage. There are at least four levels of engineering studies during development that are commonly acknowledged by the mining industry:"

Jan 1, 2016

By S. J. Aparo

Phosphate mining and beneficiation in the State of Florida are presently being carried on by 12 different mining companies with a total of 21 mining and flotation plant locations. Their combined production of both washer rock and flotation concentrate was approximately 28,000,000 long tons in 1968. This accounted for 70-72% of the total U. S. production and close to 30% of the world's output of this mineral. From this extensive activity in the Florida phosphate field, one basic flow sheet for beneficiation of the ore has developed over the years as the most commonly employed. In fact, all of these plants with the exception of two beneficiate Florida pebble phosphate using a basic operation as illustrated in Figure I. The two plants which differ from this general approach are not using raw matrix as feed. In one instance, +14 mesh pebble is ground in a rod mill to release free silica which is subsequently removed in a cationic froth flotation circuit using an amine acetate blend and kerosene. This technique generally results in a 4-7 BPL unit upgrading of the feed pebble. The other exception to the standard flow sheet illustrated in Figure I is an operation which is beneficiating tailing piles. In this case, the material is first subjected to cationic froth flotation in order to upgrade the feed to a point comparable to normal matrix. Thereafter, after, the phosphate is floated in an anionic rougher circuit followed by cationic flotation of the silica in a cleaner circuit.

Jan 1, 1969

By E. B. Fitch, D. A. Dahlstrom

Liquid-solids separation is common to practically all mineral and coal processing as the bulk of beneficiation plants employ water as the major processing vehicle. The growing usage of hydrometallurgy has increased the importance of liquid-solid separation as acidic and basic solutions result in greater amounts of colloidal solids, with their consequent greater difficulty of separation, the economic need for chemical recovery to minimize this operating cost, and the usual necessity of employing more costly construction materials. The three processing steps covered in this section have significant capital costs. Drying, particularly, has an important operating cost because of the obvious need for energy to evaporate the water or solvent. Several common factors influence all three liquid-solid separation steps. Particle Size and Size Distribution. In general, finer particles have slower settling and filtration rates. The specific surface area is increased, which means a lower solids concentration in the thickener underflow and discharged filter cake as well as a grater moisture content to be evaporated in the drying step. Therefore, overgrinding or excessive attrition should be avoided. Consideration should be given to optimum particle size consistent with entire plant operation performance and recovery. Solids Concentration. Increased feed solids concentration will generally minimize required equipment size and costs in all three liquid-solid separation steps. Most thickeners are designed on the basis of unit area required, expressed as square feet per short ton of dry solids per day (square meters per metric ton per day) which will usually decrease with increased feed solids concentration. Filtration rates also increase as the required flow through the capillaries of the filter cake decreases. Dryer capacity increases and less energy per ton of final product is required to evaporate the associated moisture. Particle Shape and Surface Characteristics. Generally, optimum shape is a spherical particle of zero porosity. As either of these factors degrade away from the desired state, difficulty increases. This is particularly true in drying, where porosity can decrease drying rate significantly if the moisture must first reach the particle surface by diffusion

Jan 1, 1985

By Ralph E. Magnuson

The quality of our environment is of great importance to all of us. Today, there is a great public concern about the degradation of our air, land, and water and the resultant slow death of our planet Earth. The miner has always been concerned with his environment. Historically, mining has been a part of the frontier. As a result, the miner has pioneered and developed many parts of the world. In the beginning, he had to hack out a place for his mine, himself, and his family. He was given accolades and praise for his accomplishments. Now, however, he is attacked as a ravager of the landscape. It was and is no different on the Marquette Iron Range in Marquette County, located in the Upper Peninsula of Michigan. Iron ore was discovered in 1845 and mining was begun by 1848. Over nearly 1 ¼ centuries, a total of 379,197,000 tons have been shipped to market. Ports, docks, railroads, and towns all had to be built in order to get that tonnage out to iron and steel makers. In those early days the environment had to be mastered, not pampered.

Jan 1, 1970

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By Jacek Galas, Stanislaw Lenczowski

The image of the flotation froth surface in the mineral processing plant contains the information about its composition. This information can be very useful for a technological process automation. Images, captured in the optical part of the measurement system were read by the computer, then were transformed and analysed digitally. The set of image parameters, extracted from an image transforms, was evaluated by statistical analysis. The recognition algorithm constructed in this process allowed to estimate the froth composition.

Jan 1, 1995

By Reed S. C. Rogers

The breakage parameters of phosphate ore were determined by batch first-order grinding studies in a laboratory ball mill according to the procedures described in the text by Austin, Klimpel and Luckie, using a slurry density of 70 weight percent. The results were scaled to five larger mills of 0.56 m diameter by 0.91 m length (2 ft. by 3 ft.), 0.82 m by 1.52 m (3 ft. by 5 ft.), 3.36 m by 7.90 m (11.5 ft. by 25 ft.), 4.41 m by 9.10 m (14.5 ft. by 30 ft.), and 5 m by 11.1 m (17 ft. by 36 ft.), assuming equilibrium ball charges for the full-scale mills. The results were used to predict product size distribustions and capacities for batch grinding in the 0.56 m and 0.82 m diameter mills and open circuit grinding in the 0.82 m diameter and larger mills using a one-large/two-small reactors in series model fitted to the residence time distribution measured in the 4.41 m diameter mill. The simulated results were compared to plant data for ranges of mill capacities. It was found that the simulated product size distributions were in good agreement with the experimental values below the 70% passing sizes, but did not agree so well in the top sizes. The predicted capacities were in approximate agreement with experimental values for the pilot-scale mills, were about 7 percent too high for the 3.36 m and 4.41 m diameter mills and about 25 percent high for the 5 m diameter mill. Use of the Bond method with the measured Work Index of the phosphate ore gave capacity predictions that were 45 to 150 percent too high.

Jan 1, 1985

By R. K. Singhal, D. B. Stewart

A variety of equipment is being used for roadheading and tunneling in the mining industry. In United States drum-type continuous miners are used most extensively. In Europe and Canada mine roadways are driven mainly by roadheaders. The application of tunnel boring machines to coal mining is somewhat recent. Such machines are however being used on major projects driving main mine entries.

Jan 1, 1985

By Norm Greenwald

The Environmental Protection Agency ("EPA") has been attempting to develop a federal regulatory program for mine waste under Subtitle D of the Resource Conservation and Recovery Act since 1986. Recent regulatory and legislative events are now bringing this goal closer to reality. This paper discusses the mining industry's perspective on a number of the issues currently being addressed at EPA's Policy Dialogue Committee and in Congressionally-sponsored negotiating sessions.

Jan 1, 1992

By Geo. A. Wells

Abstract The consumption of barytes in certain paints polyurethane foams, seamless, flooring, glass, brake linings, plastisol caskets for food containers and in fluids used for gastrointestinal X-ray examinations rely on tie unique properties of barium sulfate, There are no readily available mineral substitutes. Barytes are also the essential raw material for the manufacture of industrially important barium chemicals. High quality barite ore has become scarce throughout the world. Processing ore into quality end products is both capital and energy intensive. These factors have tended to limit availability and increase prices which have encouraged the use of alternates and restricted market growth.

Jan 1, 1980

By Clarice L. Amaral, Ricardo Melamed

Clay-coating has been used as an environmental technology tool for the immobilization of toxic elements. The mechanisms of arsenate retention in clays suggest that not only the system pH is of fundamental importance in the process but also the character of metals and ligands that compose the electrolyte system. The goal of this study was to investigate the interactions between system pH and electrolyte ions on the retention of arsenate in an Oxisol soil. The sorption of arsenate decreases with the increase in system pH, reflecting the competitive sorption of arsenate with OH groups. Solutions containing Ca tend to favour the immobilization of arsenate in a relatively broad pH range.

Jan 1, 1998

By M. E. Gershon

Extensive efforts are under way toward applying computer techniques to mine production scheduling problems. These efforts are concentrated in four areas: optimization, computerization of traditional methods, heuristics, and simulations. These areas complement each other rather than compete. Characteristics of each are discussed toward enabling the engineer to evaluate specific systems that may be encountered. Alternative approaches within each classification are described as well as the motivation for each.

Jan 1, 1987

By J. A. Finch, B. J. Huls

Accurate level detection is required to make full use of level in optimizing control strategies for flotation columns. Techniques based on pressure and electrical conductivity are compared. Pressure and conductivity profiles give good agreement on level. Level calculated from single and multiple pressure values became more accurate using, in order, one, two and three sensor locations. The level estimate remained in error, however, because, unlike the collection zone, froth zone bulk density varies with height. A conductivity probe continually updating the conductance profile is a practical method of obtaining an accurate level.

Jan 1, 1990

By Rolando V. Cuaño

For geostatistical applications, heterogeneous spatial phenomena are better modeled as mixtures of populations. However, the modeling of the constituent populations can become complex. The alternative mixture model offers a simplified approach to the w modeling problem. The model is applied and tested on the Walker Lake data set. Compared to the univariate ordinary kriging model, the alternative model generates less biased block estimates.

Jan 1, 1996