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By C Garrido, J Barrera, H Alvarez, L Perez, S Ramirez

In recent years, there has had a greater recurrence of studies and projects that consider tailings filtration followed by dry stacking to reduce the consumption of fresh water, the space required for disposal, and, eventually, to reduce the costs of the project. In addition, this technique could be required to meet new environmental restrictions to extend the life-of-mine of existing plants or to enable the development of new projects, especially in areas of high social interest. This article is intended to describe the most relevant technical aspects of the design and implementation of an iron ore tailings filtering system and its final overland disposal as well as physical and metallurgical surveys, and laboratory and pilot testing. Furthermore, it is presented how these activities are inserted in the project development to rationalise the resources. The case under study considers an iron mineral wet magnetic concentration processing plant. The outcome tailings are dewatered by means of thickeners, where the overflow water is recycled back to the plant. The underflow slurry is pumped into intermediate storage tanks before proceeding with further dewatering and final disposal. The project consists of a tailings filtration plant, belt conveying systems, a temporary stockpiling system, trucking loading and transportation system, moisture-conditioning facilities (spreading and airing), and final disposal facilities (compacting). Due to the stickiness of the filtered tailings that governs the belt conveying system design, the operating moisture range must be established. Besides, proper technical aspects such as planning, executing, and analysing both the laboratory and the pilot testing data to validate process design parameters; selecting filters; defining spare filtering capacity; handling the out-of-range filtrated moisture; sizing the belt conveying system; configuring the equipment involved, must be considered.

Nov 8, 2021

The purpose and current practice of cable trusses in underground coal mines is briefly outlined and details of various cable truss designs are presented. The main part of the paper describes the in-situ performance of cable trusses installed as secondary supports in gateroads and recovery roads of longwall coalfaces. The performance analysis is based on the results of in-situ monitoring carried out at a number of sites at two underground coal mines within Australia. Truss performance has been assessed as load developed in relation to roof convergence, face position and time. Additionally, the influence of strata conditions, installation pattern/density, roadway layout and geometry have been taken into account. An analytical model has been developed to predict truss loads. The principal variables are listed and the basis of the model is described. Based upon behaviour observed in the field the model has been progressively upgraded and validated against measured performance. Guidelines on truss performance and factors which influence it are presented and the implications of these to the use of cable trusses is discussed. Possible methods for improving truss performance in certain strata conditions are outlined and some comments are made on the value of cable trussing compared to cable bolting in these situations,

Jan 1, 1992

By Fuller P. G

The purpose and current practice of cable trusses in underground coal mines is briefly outlined and details of various cable truss designs are presented. The main part of the paper describes the in-situ performance of cable trusses installed as secondary supports in gateroads and recovery roads of longwall coalfaces. The performance analysis is based on the results of in-situ monitoring carried out at a number of sites at two underground coal mines within Australia. Truss performance has been assessed as load developed in relation to roof convergence, face position and time. Additionally, the influence of strata conditions, installation pattern/density, roadway layout and geometry have been taken into account. An analytical model has been developed to predict truss loads. The principal variables are listed and the basis of the model is described. Based upon behaviour observed in the field the model has been progressively upgraded and validated against measured performance. Guidelines on truss performance and factors which influence it are presented and the implications of these to the use of cable trusses is discussed. Possible methods for improving truss performance in certain strata conditions are outlined and some comments are made on the value of cable trussing compared to cable bolting in these Situations.

Jan 1, 1992

By Allan Breitenbach

Leaching has been used since the 1600s on unlined ore dumps and since the late 1970s on lined leach pads for the recovery of metals from mined ore, the latter typically called ?heap? leaching and the former ?dump? leaching. Modern day run-of-mine (ROM) or crushed ore heaps are stacked in controlled lifts on lined leach pads and irrigated with a solvent solution (dilute alkaline cyanide for precious meals, dilute sulfuric acid for base metals and uranium). Conventional lined leach pads store process solutions and any storm water, snow melt and cumulative wet season surplus water by gravity flow to external ponds. Impounding valley leach pads (also known as valley fill heaps) differ from conventional leach pads by storing various combinations of process liquid solution and surplus water within internal ponds by using the interstitial pore volume of the ore. While impounding liquids within the heap is simple in concept, impounding leach pads are more complicated for construction and containment compared to conventional leach pads with external ponds.

Jan 1, 2012

By A. D. S. Gillies, A. Haghighat

"A study has been undertaken at the Missouri University of Science and Technology (MS&T) limestone Experimental Mine to determine new fans set up and wiring options.to install additional mine ventilation capacity. Selection for main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Available fans for ventilating the mine are Joy and Alphair axial fans each of 24 kW each and two Spendrup booster fans of 12 kW each. The installation of main mine fans on the surface and underground entails numerous considerations. Design of a ventilation network for the Experimental Mine incorporating surface and booster fans has been accomplished using Ventsim Visual program software. The ventilation network has been separated into two segregated parts. A main surface fan and a booster fan have been used in each segregated part of the network. The mine has had a vane axial Joy fan in place for many years. The Alphair 4800 VAX 1800 full blade adjustable pitch vane axial fan was selected and installed as the other surface fan and eventual replacement for the Joy fan. Main surface fans have been connected individually to booster fans in series. The Alphair main surface fan has been installed vertically. Four different wiring options and related cost estimations for addition of the new main fans to the ventilation network have been considered. The analysis resulted in an innovative steel frame design used to allow the fans, when necessary, to be moved to the side of the shaft so that blast pressures do not damage the blades. INTRODUCTION Main fans are the heart of a mine’s ventilation network and play a key role in supplying required airflow (Haghighat, 2014). The Missouri S&T Experimental Mine has been developed in uniform limestone with few stratigraphic features. The mine floor is approximately horizontal and water drains well. A study has been carried out on MS&T Experimental Mine. Selection of main fans has been undertaken according to the mine’s required performance specifications and fan characteristics. Ventsim Visual computer simulation has been used to assist in design of the ventilation network. Wiring circuits, fan foundations and flexibility have been considered as the three main parameters for surface fan installation at the Experimental Mine. Two surface and two underground wiring options and three surface set up options and related cost estimates for the new surface fan system were investigated. Frequent use of explosives in the mine occurs throughout each year. Flexibility in changing the position of a surface fan is important. A number of options have been considered for the location of a vertical main fan positioned on the upcasting shaft. The mine is used for a variety of purposes and flexibility has a high priority amongst design considerations."

Jan 1, 2015

By Cameron J. Clayton

Cumberland Resources Ltd. is currently planning to develop the Meadowbank Gold Project located some 70 km north of Baker Lake, Nunavut in the eastern Canadian Arctic region. The Meadowbank Gold Project currently consists of up to 6 main gold bearing deposits within relatively close proximity to one another which are planned to be mined primarily as a truck-and-shovel open pit operation and using conventional gold milling and extraction. The mining plan indicates that approximately 20 million tonnes of ore will be mined over a mine life of 8 to 10 years. The operation will generate approximately 160 million tonnes of mine waste rock and about 20 million tonnes of tailings. The site is located in an area of continuous permafrost with mean annual average air temperature of -11 °C and average annual precipitation in the range of 100 to 200 mm. Lakes cover a large portion of the site, including some of the ore deposits. The location of the site, and the physical environment, pose challenges to development. This paper presents some of the designs considered to effectively manage and utilize the waste products of mining at the project.

May 1, 2004

By C. J. Clayton, A. J. Haynes, D. A. Hickson, B. Thiele

The Meadowbank Gold Project, formerly owned by Cumberland Resources Ltd. and currently owned by Agnico Mines Ltd., is currently being developed approximately 70 km north of Baker Lake, Nunavut, in the eastern Canadian Arctic region. The Meadowbank Gold Project currently consists of a series of gold-bearing deposits within relatively close proximity to one another, which are planned to be mined primarily as a truck-and-shovel open pit operation using conventional gold milling and extraction. The mining plan indicates that approximately 20 million tonnes of ore will be mined over a mine life of eight to ten years. The operation will generate approximately 160 million tonnes of mine waste rock and about 20 million tonnes of tailings. The site is located in an area of continuous permafrost with mean annual average air temperature of -11°C and average annual precipitation in the range of 100 to 200 mm. Lakes cover a large portion of the site, including some of the ore deposits. The location of the site and the physical environment pose challenges to development. This paper presents some of the designs considered to effectively manage and utilize the waste products of mining at the project. Note that volumes, tonnages, construction concepts, and data presented in this paper are accurate for the time of writing and are subject to change and modification as the project progresses, additional modelling is carried out, and additional data are obtained.

Jan 1, 2007

By James P. Ludwig

While we are all aware of the need for reclamation of mine sites, few managers and engineers seem to be aware that good reclamation begins with the earliest plans for mining and processing of ores. Far too often the attitude that reclamation is an add-on to worry about at the end of the mining process dominates the thinking of mine engineers and management, A common result is that the reclamationist can be faced with mining and waste disposal designs that are nearly impossible to deal with effectively from an ecological perspective. Everyone of us has been victimized by the down time and maintainence cost that resulted from the purchase of an outwardly attractive, but poorly designed piece of equipment. When confronted by design defects in equipment, a distraught owner can always trade it in, call a consumer advocate, or follow up one of the "lemon laws" at either the federal or state level. A poorly designed mine for reclamation purposes usually cannot be treated either with ease or cost effectiveness. Good reclamation can be effectively prevented by the designs used when the mine was planned. The purpose of this paper is to share some of the experiences our firm has had with reclamation projects at mines in the Upper Midwest as these were influenced or controlled by mine design decisions. My aim is to sensitize mine planners and managers to planning processes they should consider, and hopefully use, early in the mining process to assure successful reclamation during and after mining. Many of the examples I will cite are from experience gained at the recently closed Jackson County Iron Company taconite operation at Black River Falls, Wisconsin. I am particularly grateful to Mr. Vern Metzger, mine manager at JCIC, for his unflagging support of good reclamation practices, employee training programs (which have included reclamation techniques), and his forebearance to put up with our group of ecologists. I realize that this was a time when there were significant internal and external pressures to cut all costs including reclamation efforts. The collaboration has been successful as you will soon see.

Jan 1, 1984

By J. M. Keane

SMEThis loaner is concerned with important criteria relative to the design of small flota¬tion concentrators. For the purpose of this discussion a small flotation concentrator is defined as a facility having a designed ore feed rate of 1,000 metric tons per day (MTPD), or less. The decision to design and construct a small flotation concentrator is the culmination of a series of logical steps relative to the ex¬ploitation of a potential ore body. The information required for a rational and timely decision regarding plant design and construction is usually contained in a feasibility report. The information required in a thorough feasibility report has been summarized (1) (2) as follows: Type of mine or plant and proposed daily, monthly, and yearly production of all intermediate and final products. Quantity of indicated ore reserves. Location of project illustrated by a map showing surroundings, trans-portation facilities, and existing utilities.

Jan 1, 1980

By M. Karmis

Subsidence planning and control must be an integral part of mine design in order to minimize the economic impact of underground mining on the surface. Pre-calculation of surface deformations which may cause damage to surface structures must be performed and dam-age criteria must be established, if the response of structures to such movements is to be determined and the extent of damages to be assessed. In this paper the Surface Deformation Prediction System (S.D.P.S.), which can be used to predict accurately the vertical and horizontal parameters of surface movements due to underground mining, is discussed. The Subsidence Response Modeling Program (S.R.M.P.). which can be applied to evaluate the response of buildings to subsidence-induced movements, is also reviewed. Finally, an example is presented demonstrating the applicability of these techniques for subsidence design and control.

Jan 1, 1990

By Mohammed Z. Islam

As cities are growing all over the world, the need for urban transportation facilities are on the rise. Designers (of these facilities) today are faced with a number of constraints for their design, of the most is the space limitation and impact of new construction activities to the community. A typical subway station, as the focus of this paper, is approximately 600 to 1000 feet long, 50 feet wide and 2 to 3 story high. With such a large volume of construction activities, it is easily realized why underground stations are becoming obvious choice for larger cities eventhough the cost could be 2 1/2 to 3 times as much as an aerial station and 4 to 5 times that of an at-grade station [O'Neil et. al.(1977)]. Since cost is an important factor which is always increasing, therefore, the designer should have a good planning, consider alternatives for design and come up with a realistic design with minimum impact to the community. This paper is about the geotechnical considerations that the designer should be aware of. PLANNING A 1977 report [O'Neil et. al.(1977)] on the construction costs for a number of underground subway stations indicate that about 4 0% of the cost is site-controlled, 35% is structural items, and 25% is finish and equipment. It is seen that of opportunity exists for cost savings in the site selection and proper use of the site. Once the site is selected, the cost of construction become controlled by urban conditions at the site, geotechnical conditions, station size and depth. Therefore, the design-solution is very much site-specific. The geotecnical designer should collect the following information at the early phase of the design:

Jan 1, 1993

By J. A. Holmes

Due to varying and complex mineralogy, the flotation tailings from the Chingola Concentrator have, for some years, contained upwards of 0.4% acid soluble copper. In 1968, an investigation was initiated, to determine a method for recovering this acid soluble copper. This initial investigation concluded with a recommendation to install a leach-solvent extraction-electrowinning plant at Chingola, to treat up to 900 000 tonnes of material per month, for an additional copper production of some 4 500 tonnes per month. The process consists basically of six stages :- Materials reclamation handling and preparation, acid leaching in air agitated pachucas, solid-liquid separation by countercurrent washing in thickeners, solution concentration and purification by solvent extraction, copper recovery by electrowinning, and residue neutralisation and disposal. This paper describes the development of the main parameters for design of each of the six sections, and gives details of the final plant design. Problems encountered in commissioning and initial operations are commented on, particularly insofar as they indicated any errors or misjudgements in the design. The choice of materials of construction is commented on in some detail.

Jan 1, 1976

By C. R. McKee

In-situ mining of hard rock deposits will only become successful as we understand the engineering parameters involved and the design limitations they impose. As recognized by Wadsworth1 the most critical area is the enhancement of permeability in a hard rock mass. Along with creating permeability, the appropriate flow and fragment size conditions must be generated to insure economic rates of mineral recovery. In this article our interest is confined to true in-situ processes in which boreholes are drilled from the ground surface or a mine drift to deeper strata. We assume that fractures and permeability enhancement will be due to explosives detonated in boreholes. Other techniques such as hydraulic fracturing do not produce the necessary size distribution to promote economic extract ion rates unless the medium is already highly fractured and interconnected. Notable exceptions where hydraulic fracturing is applicable are many oil, gas and salt deposits. For many in-situ processes, an array of explosive charges offers the opportunity of creating a distribution of many fractures not achievable by other techniques. Such a situation would be suitable, for example, to in-situ mine hard rock gold, uranium, copper or oil shale deposits and may enhance oil and gas recovery in certain situations. The purpose of our article is to review and extend the explosive permeability theory of McKee and Hanson 3,4,5 and to apply its results to derive design parameters suitable for in-situ mining.

Jan 1, 1981

By Charles V. Riley

While the late 1960's are known as the years of the public recognition of impending environmental crises, the 1970's will be known as the decade of public concern for improving the quality of that environment. One of the present major environmental concerns is the temporary disturbance resulting from coal surface or open cast mining. To realize that this concern will continue in the future, one need only observe the daily news media. Increasing energy demands in the U.S., a doubling of electrical power consumption each decade during the present century, and the projected needs for the remainder of the century are indica¬tions that coal surface mining as a major extractive industry will continue. Coal and lignite, prime energy resources and extremely abundant in these United States, in the face of seemingly limited gas, oil and uranium reserves, are both destined for expanded future use. Presently some extremely serious techno-logical and environmental problems are associated with the develop¬ment and use of nuclear power. It is true that the extraction and use of coal as an energy fuel poses disruptive problems for the environment, but the solutions to many of the problems are known or can be solved within a reasonable time framework. Certainly our national well-being and continued survival, as a free nation within the world community, automatically dictate the continued use of the coal resource for energy. Concurrently, those engaged in coal surface mining, with the temporary disturbance of the land and water resources, must also realistically conclude that public concern for maintaining and improving the quality of the environment will not diminish. Although as ecological, economic, social and aesthetic elements

Jan 1, 1972

By John W. Scott

INTRODUCTION The design criteria for a particular concentration and dewatering project will provide the formal basis for design of the process, equipment and facilities. These criteria will specify the required capacities and operating schedules for the equipment, as well as the quantity and quality of the feed to be processed and products obtained. The general climatic and geographical conditions at the site, specific information on soil or rock conditions; and applicable design standards and codes will also be included. The design criteria will generally be based on an interpretation of testwork carried out on the particular ore and site, and will thus parallel in detail and completeness this testwork. As the project moves from the early conceptual phases through to final detailed design, the design criteria will be developed and become more detailed as information is generated and made available for use. The design criteria are critical to the design effort as the formal specification to the designer of what and how much is to be processed, what and how much is to be produced, and where and under what conditions. The actual design criteria will be a formal tabulation of the design basis information developed for the project in question. For a preliminary study, this may consist of a single page of data; for a feasibility study several pages and for a detailed design up to several hundred pages and multiple volumes. Depending on the complexity of the process and the level of detail included, each project will be unique to some degree. The design process for a project normally progresses from preliminary conceptual phases through to a final detailed design. The criteria used for the initial concepts are generally developed from rough data and preliminary testwork on the ore in question. Regardless, the plant throughput and products are defined, thus giving a scope and definition to the study phase. In some studies a range of throughputs may be analyzed in order to arrive at the most economically attractive size for the proposed operation. This optimum size is then used as the design throughput for the more detailed design phases. Similarly as more testwork results are available and the ore characteristics and process become more well defined a continuous updating of the design criteria is undertaken.

Jan 1, 1986

By Paul M. Wiltcher

This paper discusses how benefits in engineering design can be achieved from combining existing GRP concrete design guidelines with carbon steel design codes primarily made possible due to the increase in the constitutive properties of modern composite rebar or GRP. It also examines the technical and practical considerations necessary to both construct and ensure the integrity of composite rebar during transportation and handling on site and the measures taken by Franki-Cementation Joint Venture to ensure the safe deployment of the GRP in the workplace on the Noord/Zuidlijn Project in Amsterdam between 2003 and 2006.

Jan 1, 2006

By Aaron Archer, James Parkes

This paper presents design considerations for the major underground elements of the pending BCRUA Phase 2 Raw Water Delivery System Project. These elements include two Lake Taps; an 8,800 LF, minimum 10-ft OD intake tunnel; a suction chamber with 6 Pump Shafts; a 30-ft diameter, 300-ft deep Main Shaft; a 2,600 LF Transmission Tunnel with 78-inch steel liner; and a 130-ft deep shaft on the Transmission Tunnel. The tunnels and shafts will be excavated through the Glen Rose limestone. The design development included consideration for technical requirements, easements, third party commitments, previous local project experience, and constructability based on contractor outreach.

Jun 13, 2021

By Joseph Goessling, Mark Kroncke, James Parkes

The I-35 Capital Expressway (CapEx) Central Drainage Tunnels will serve as a stormwater collection system for the forthcoming I-35 Capital Express Central reconstruction project through downtown Austin, Texas. The schematic level concept design included three tunnels, 10 to 14 ft ID, totaling 26,000 LF. Constructability reviews during design development indicated issues with the concept design including phasing of construction, conicts with future retaining walls, staging area concerns, and signicant mixed face tunneling. The design was updated to mitigate these risks. The revised design includes two tunnels, both 22-ft ID and totaling 33,000 LF, that will be mined almost entirely in rock.

Jun 23, 2024

By R. Schuerch, G. Anagnostou, R. Poggiati

"The paper presents dimensionless design diagrams for estimating the stand-up time of a tunnel face in saturated ground of medium-low permeability. The diagrams cover a wide range of ground parameters and apply to shallow tunnels (overburden less than two diameters). As the time-dependency of the face stability in water-bearing ground is associated with the consolidation process in the soil ahead of the tunnel face, the stand-up time is determined by means of hydraulic-mechanical coupled spatial stress analyses. The results presented are important for tunnel engineering practice, e.g. when estimating the feasibility of atmospheric interventions in the working chamber of a closed shield. INTRODUCTION The response of water-bearing medium-low permeability ground to tunnel excavation is time dependent. The time-dependency is due to a transient seepage flow process that is triggered by the excavation and develops slowly over the course of time. Experience shows that the short-term behavior the ground is more favorable than the long-term one: the deformations increase with time; the tunnel face may be stable initially and fail only after some time. The time over which the tunnel face remains stable is called the stand-up time. This paper investigates the time dependency of the tunnel face stability assuming that all time effects are due to consolidation rather than creep. This assumption is reasonable for shallow tunnels crossing water-bearing soils. In the problem under analysis, the unsupported tunnel face remains stable under the undrained conditions prevailing after excavation, but collapses before reaching the drained conditions prevailing at a steady state. The assessment of the stand-up time is important from an economical point of view for both mechanized and conventional tunneling through weak water-bearing ground, as a long stand-up time removes the need for face support or ground improvement works during standstills, thus saving time and money, while short stand-up times require hyperbaric interventions or the implementation of costly and time-consuming auxiliary measures."

Jan 1, 2016

By Alan F. Stewart, Douglas R. Piteau, Dennis C. Martin

Three examples of open pits where toppling failure controls the stability and design of the slopes are described. Two examples involve the design of overall slopes in base metal mines. The third example concerns the analysis and design of remedial measures to prevent toppling failure from occurring in a critical slope in a coal mine. The analytical techniques for assessing toppling failure on a rational basis are discussed for the three examples. This includes an assessment of the important parameters which govern the stability for the toppling failure mode. The geological setting and input data for each example are described, as are the important external or limiting factors pertinent to the sites in question. A statistical cumulative technique was used to assess one of the most important input parameters in the two examples involving overall slope design. Both deep-seated toppling failures, involving the entire slope, and shallow bench failures are considered. Results of the stability analyses and their related engineering significance with regard to slope stability and design are discussed. A sensitivity analysis of various parameters is effectively utilized. Design charts are developed and evaluated accordingly. In the example where toppling failure was unavoidable, the rationale for design of stabilization techniques to prevent toppling is discussed.

Jan 1, 1983