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By Emily Sing, Ashim Gajurel, Thomas Pennington, William Brown

The Pardee Chemical Feed Shaft Project involves construction of two new chemical feed shafts to improve raw water treatment capabilities at the East Bay Municipal Utility District’s (EBMUD) Pardee Reservoir in Valley Springs, California. The project includes construction of two 250-foot deep, 16-inch diameter stainless steel chemical feed shafts that penetrate an existing 8-foot diameter concrete lined conveyance tunnel. The design approach required the shafts be installed using top-down drilling methods and within a strict verticality tolerance (0.1%). Innovative precision drilling techniques ensured that the shafts penetrated the tunnel in their planned locations and the installed chemical feed lines would function as designed. Challenges included extremely limited access to the tunnel because of a requirement to maintain the tunnel in service during construction. This paper discusses the overall project’s design and construction approach, including unanticipated conditions that the project team faced and how these conditions were managed and overcome through collaboration between the contractor, designer, and owner.

Dec 1, 2022

By Eduardo Rojas, Pedro Landeros

El Teniente Mine expansion plans are currently under development and construction stages through an integrated project strategy that will allow the continuity of future mining. The deepest sector corresponds to Andes Norte Project that faced rockburst risks during tunneling in a completely different manner, implementing different actions for the mitigation of seismic hazard and seismic risk management, based on the following main aspects: rock mass preconditioning techniques such as destress blasting and hydraulic fracturing, improvement of rock support design with the inclusion of elements with higher energy dissipation capacities, use of mechanized equipment for the most critical activities in addition to re-entry protocols and improvements in geological, geomechanical and seismic data collection procedures to reduce the uncertainty of rock mass behavior. The current seismic risk management strategy integrates all of these elements and is the basis of construction methodologies in use, supporting the technical feasibility of tunneling in high-stress environments.

Apr 26, 2022

By J. P. Golightly

The structure and occurrence of nickeliferous laterite profiles are described and explained in terms of mineral solubility and drainage conditions. Complete profiles, from top to bottom, include: limonite zone; nontronite or silica zone; and saprolite zone. The middle zone is present only where drainage is sufficiently slow to allow saturation conditions to build up with resulting quartz or smectite precipitation. This precipitation may occur in any climate at a water table or in tropical climates with a long dry season. The degree of serpentinization of the laterite parent rock is important in determining the nature of the saprolite zone. Unserpentinized peridotite produces saprolite ores with hard residual rock cores, nontronitic or amorphous saprolitic rims, and fracture fillings of garnierite and quartz. Ser-pentinites yield relatively homogeneous serpentine saprolite, with minimal quartz or garnierite.

Jan 1, 1979

By B. C. Paul, R. Q. Honaker, M. Huang

Froth flotation is now, the most commonly used method for cleaning fine-coal fractions in coal-preparation plants. Past research and industrial practice have demonstrated that froth flotation achieves excellent separation efficiencies for fine coals having only a small fraction of middling particles. However, the efficiency of froth flotation decreases sharply as the concentration of middling particles increases. This is due to the flotation of high-ash particles that have a small amount of hydrophobic coal present at the surface. Because gravity-based processes are much more efficient for the treatment of middlings, the application of centrifugal washing for fine-coal cleaning was studied with an emphasis on the primary cleaning of fine-circuit feed. Results are shown of a parametric study that used a semibatch Falcon centrifugal concentrator. The results of the study revealed that separation performance is a function of particle size, bowl geometry, feed solids content and feed rate.

Jan 1, 1996

By Rasik H. Raythatha

Calcium carbonate is perhaps the most widely used mineral in the world. With total consumption of all calcium carbonate exceeding over 25 million tom per year, within this class of filler, a relatively smaller segment of precipitated calcium carbonates (PCC) is often misunderstood as a commodity product and bundled in the same category as ground calcium carbonate. However, each material has a distinctly digerent role and characteristics. Precipitated calcium carbonates are used to influence specific performance in a specific application whereas ground calcium carbonate is used primarily to reduce cost in many applications. In this paper, attempts are made to demonstrate the role of nano-fine-PCC in improving shear-thinning characteristics of common and specialized sealants and automotive underbody coating and how such "nano-particle" cal- cium carbonate properties can be exploited to process PVC plastics while reducing overall cost. We also review the role of precipitated calcium carbonate as "nano" material and why it must be viewed as a specialty additive.

Jan 1, 2003

By K. Pietruszka

The article presents the concept of the application of the Finite Element Method (FEM) and ABAQUS software in the global monitoring of changes in the rock mass and on the surface of the area, as a result of backfilling the workings. Waste materials applied for stabilizing old mining workings can have a strong influence on the rock mass and surface. According to the regulations, this process should be carefully monitored, especially in terms of the safety of surface structures and rock mass stability. The article presents the concept of an analytic and graphic presentation of the results of the measurements of old workings, applying the Finite Element Method and ABAQUS software in model studies. The main purpose of such interpretation of the geodetic observations results is the application of methods providing wide possibilities to present the geometry of workings, their changes and the influence of the rock mass and surface.

Jan 1, 2008

By Kevin Sharman, Peri Mehling

A detailed assessment of acid rock drainage (ARD) potential was conducted at the Quintette Coal Mine site in northeastern British Columbia The site is unusual in that the coal seams contain low sulphur levels as compared to eastern coals (typically less than 0.5%), and the non-coal wastes generally do not to have the potential to generate acid on the basis of static ABA tests. The presence of small iron-stained seeps on the pit walls indicate localized sulphide oxidation, while the overall mine site drainage has remained of excellent quality with extremely low levels of metals after approximately 15 years of mining. Thus the site provides an excellent comparison to more problematic coal mine sites. For the Quintette assessment, static acid-base accounting (ABA) analyses of individual samples were compared to criteria for potentially acid generating materials developed for the U.S. Appalachian coal, as well as criteria developed in British Columbia for hard rock mines. Geologic units were characterized by the percentage of samples, or weighted thickness, that was deemed potentially acid generating (PAG). Links were then made to actual seepage and water quality emanating from geologic units around the site. Seeps at the site demonstrate a large range in pH (2.32 to 8.18). The few acidic seeps (pH < 4.0) were found to contain elevated levels of sulphates, dissolved iron, manganese and aluminum, consistent with the metals typically of concern in Appalachian coal mines. Other heavy metals that were detected in acidic seeps at Quintette included copper, zinc, nickel and cadmium. The use of simple ABA tests, and comparison of individual sample results with the Appalachian and British Columbia criteria, was found to be useful in predicting the probable sources of the small localized acidic seeps.

Jan 1, 2000

By Dipl. -Ing. H. -J. Sager

The ‘Westerschelde Tunnel’ underpasses the estuary of the Schelde in the Netherlands. The tunnel will consist of two tubes which are driven by two hydroshields (slurry shields). The tunnels will each have a length of approx. 6.6km and a bore-diameter of 11.33 m. Demanding ground conditions had to be considered during the design of the shield machines. Loose sands, extensive clay formations and high ground water pressures of up to 6.5 bar will be encountered during the tunnel drive. The tunnelling activities will start in the middle of 1999 and are scheduled to end by the end of 2001.

Jan 1, 1999

By R. J. Sweigard, R. V. Ramani

Three case studies were undertaken to investigate the role of land use potential evaluation in reclamation planning and to determine the impact of regional differences on final land use plans. The three surface mines studied were representative of operations in the Appalachian, Interior, and Northern Great Plains provinces. The scope of the investigations included a survey of regional characteristics, a detailed investigation of the mining operations and site conditions, and an assessment of local land use planning activities in the area of the mines. Special attention was given to key factors that presently determine the use of reclaimed land. Also, for each case study, the postmining land use potential was evaluated using site planning principles. Specifically, the environmental, economic, and social impacts of several potential postmining land use plans were considered.

Jan 1, 1987

By T. E. Wilson

The length of Alaska&apos;s coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, the decision-making process is complex because various factors govern the viability of the submarine tailings disposal (STD) option. An expert system, called the Submarine Tailings Disposal Expert System (STADES), was developed to help mining project planners explore the feasibility of STD. A review of the existing literature, supplemented by engineering recommendations, on the various aspects of the marine disposal of tailings formed the knowledge base for the expert system. The shell used to develop the expert system was LEVELS.

Jan 1, 2003

By G. Rinelli, Paul R. Jr. Smith

Preparation for flotation begins with dragline mining, pumping, washing, screening, and desliming. Slimes, nominally -150 mesh material, constitute large quantities of phosphate and water which are a disposal problem. Older techniques involve sizing at about 35 mesh for separate coarse and fine treatment. The plus 14 mesh fraction does not require concentration. Coarse treatment includes agglomerate spiralling, belt flotation, thickening, scrubbing with sulfuric acid, de-oiling for reagent removal, and cationic flotation of fine quartz. A recent trend is to screen at coarser than 35 mesh size and eliminate coarse particle treatment, sacrificing some grade of this product. Techniques for flotation concentration of the fine size fraction are discussed.

Jan 1, 1976

By R. A. Metz, M. A. Bryant, J. C. Goodwin, T. B. Faddies, L. D. Kornze

The Mercur Gold Mine is located 56 km (35 air miles) southwest of Salt Lake City in north central Utah. In July 1981 Getty Mining Company made the decision to put Mercur into production. The first gold bar was poured in April 1983. This paper provides details on: 1) the history of the camp, 2) past production, 3) geology of the deposit, 4) the exploration and development program, 5) ore reserve estimates, 6) detailed geologic pit mapping, 7) production blasthole sampling techniques and 8) the use of geostatistics (kriging) in handling assays and gold extractions to produce the required mill feed.

Jan 1, 1992

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 O. Tsuge, G. Hoffman

ITmk3®(Iron Technology Mark III) is an innovative new ironmaking technology whereby high quality iron nuggets are produced directly from iron ore fines and coal in a rotary hearthfurnace1). The reaction mechanism has been investigated in detail through fundamental laboratory research2)3), and the ITmk3 process has progressed from the laboratory to commercialization by the success of the pilot plant tests initiated at Midrex’ Technical Center and at the Kakogawa Bench Plant (KBP) located at Kobe Steel Ltd. Kakogawa Steel Works4)5). Pilot operations have demonstrated rapid production of the iron nuggets with complete metal/slag separation at a relatively low operating temperature. The Kakogawa Bench Plant (KBP) in Japan has logged 21 days continuous operation during which high quality iron nuggets were produced directly from fine ore and coal. The operation technology and the engineering data obtained from these pilot tests were instrumental for the scale-up of the ITmk3 process for the Mesabi Nugget Corp. pilot demonstration plant, which is located at Cleveland Cliffs Inc. Northshore Mining iron ore pellet plant in Silver Bay, MN. The ITmk3 process is an ideally suited technology for siting at the iron ore mine, as it allows the economical production of a value-added merchant iron product.

Jan 1, 2003

By M. Scherzinger, M. Dr. Mazurkiewicz

Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests and generated results and conclusions are the subject of this paper. It covers tests with different jets imposed on rock samples during compressive load as well as without any loading.

Jan 1, 1992

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

The Northside Storage Tunnel Project in Sydney includes over 20 km of TBM driven tunnels, over three km of declines and major caverns and pump rooms. The paper describes methods used for design on the project. Emphasis is given to the refinement of the use of empirical rock mass classifications, and to the use of discontinuum numerical methods. The use of empirical rock mass classifications in Sydney sandstone has usually led to conservative design because the systems are based on a random orientation of joints in the rockmass. Because the joint sets are usually oriented in a way that is beneficial for tunnelling, limits must be placed on the parameters used in the classifications system. The paper discusses these limits and the derivation of the parameters. The use of numerical methods in Sydney sandstone is discussed. Continuum methods have their uses, but discontinuum methods are preferred. The use of UDEC has been validated against a previous project, the New Southern Railway. Recommendations are given for UDEC models. In Sydney&apos;s geology, so advantageous for tunnelling, the challenges of this project have been to make the best use of the good conditions, while maintaining safety for the workforce and the future operators of the project.

Jan 1, 1999

By R. Tanaskovic

Unfavourable climatic conditions in stopes are of significant economic and social importance due to the following reasons: - Working effect is much lower leading to decreased output and work productivity disregarding implementation of mechanization. - Manpower operating capability decreases much faster under unsatisfactory climatic conditions. Under normal climatic conditions a workman would expend much less effort in line with a shorter effective time for the achievement of identical production effects since the work would be more efficacious. The objective of study of problems and climatic conditions is to make the working environment in mines suitable for normal development of operations. Lowering of mining works to increasing depths and winning of a growing number of small orebodies over a broad area makes the problem of creating suitable climatic circumstances more complex. Mining costs are growing due to bench conditions in line with decreasing metal content in the ore, so frequently the investments required for creating favourable climatic conditions represent, in addition to the selection of mining technology, a very important parameter when making decisions regarding exploitation. As known, the basic factors affecting climatic operating conditions in mines-are: temperature, humidity and speed of air flow, implying that the climatic operating conditions are closely related to mine ventilation. Usually, the concept of unfavourable climatic operating conditions includes increased mine air temperature and humidity and low air flow velocity so that heat exchange between human organism and the working environment is impeded or reduced to minimum. Metal mines in Yugoslavia are characterized by the existence of a large number of active faces - stopes and horizons and lowering of mining operations to increasing depths, so that face ventilation solutions are more and more complex. Since its foundation (1961), our Institute is engaged in investigation of factors influencing climatic circumstances improvement of calculations for air distribution and distribution control in complex ventilation networks and study of problems related to ventilation of large volume and irregular configuration faces, as well as application of gained knowledge in our mines. The paper presents the knowledge and experience gained in the case of Lead and Zinc Mine "Trepca" - Stari Trg.

Jan 1, 1980

By Robert D. Hansen, Basil S. Fee, Richard R. Klimpel

Despite the importance of froth flotation to the mineral industries as a means of separating various minerals, the commercial flotation reagents used have varied little in the last twenty years. Numerous articles and books are available describing existing flotation chemistry and its application, e.g., Fuerstenau (1962), Fuerstenau (1976), Aplan (1980), Somasundaran (1980), King (1982), Leja (1982), Ackerman, et. al. (1984), Crozier (1984), Hansen and Klimpel (1985). There are many reasons for this lack of significant new reagent development including the general utility and relative cheapness of collectors, such as xanthates, and frothers, such as methyl isobutyl carbinol and the glycol ethers. Another important reason is the inherent complexity of the flotation process itself coupled with highly variable and difficult to standardize feed materials which make reliable reagent comparisons difficult and seriously limit the use of theoretically based studies to "predict" new or optimal reagents. In addition, the higher cost of "specialty flotation reagents demands that their performance attributes be significantly greater than existing general all- purpose commercial reagents – something often difficult to prove in practice. Faced with this situation, a detailed applications research pro- gram [Klimpel (1980 ab, 1982, 1984 ab), Klimpel, et. al. (1982)] was organized from 1979-1985 on mineral flotation with the following goals: 1) the development of appropriate batch laboratory flotation testing techniques sensitive enough and statistically reliable enough to identify small differences in performance between different flotation tests (i.e., between various reagents, even those with relatively minor chemical structural changes); 2) the identification of mathematical models with appropriate numbers and types of parameters that have maximum statistical power to statistically distinguish between various time-recovery profiles; 3) the generation of laboratory and corresponding plant scale data in sufficient quantity and consistency so that the highly interactive nature of the "flotation system9&apos; of chemistry/ equipment/operating conditions could be quantified; and 4) the invention and development of really new and unique reagents for giving improved flotation performance. The goal #1 was achieved [Klimpel (1980b. 1984b), Meyer and Klimpel (1984)l by basically using a simple automated paddle device for consistent

Jan 1, 1986

By R. Herrera-Urbina, D. W. Fuerstenau

A large number and a wide variety of chemical reagents are used in flotation processes for wettability and Eh control, particle agglomeration/dispersion and bubble stability. A historical account of the use of flotation reagents through the years since flotation was introduced as a viable and economic process for the concentration of sulfide minerals is given and a review of old and modern postulates of their interaction with minerals is presented. Although the results of surface and colloid chemistry studies with well characterized mineral/flotation reagent systems have advanced our understanding of the role played by these chemicals in the flotation process, many questions remain unanswered. Moreover, new flotation reagents are needed to solve the challenge posed by the treatment of problematic-type ores and fuel deposits that have increasingly become the source of our raw and energy materials. Because of the depletion of high-grade and relatively easy-to-process ores, flotation scientists and engineers are confronted with finding more specific and selective flotation chemicals to effectively and economically concentrate minerals. The development of new flotation reagents is vital for cleaning fine coal and processing polysulfide, polymetallic ores, and mixed oxide/sulfide ores.

Jan 1, 1989