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By Terry M. Hertel

Zortman Mining has spent approximately three years evaluating the metallurgy of the sulfide ores from the mining area of the possible expansion project. As the test program proceeded, an interesting series of events took place which changed the scope of the work. During the agglomeration work, one of the control columns was inadvertently set up without the addition of lime to the material prior to loading and subsequent leaching. The gold recovery from this column was comparable to those columns that had a lime addition of 10 pounds per ton of ore. In fact, the gold recovery curve had a much steeper slope than those of the other columns. Furthermore, the pH of the pregnant liquor from the "no lime" column recovered to typical levels as fast as the solutions from the "lime" columns. These observations led to the concept that rinsing the ore with water prior to cyanide leaching could be advantageous to the heap-leach process.

Jan 1, 1992

By J. W. C. Wong, T. A. Songberg, S. D. Miller, J. J. Jeffery

Natural degradation of cyanide has been widely used by the gold mining industry for removal of CN from cyanidation processing wastes. However, little documented study has addressed the decay and fate of cyanide within residue storage ponds. 'fhis paper describes a study on the cyanide behaviour in a residue storage pond at the Boddington Gold Mine in Western Australia. Depth profile samples were collected from the active residue storage to determine the distribution of CN forms and complexing metals throughout the settled residue.

Jan 1, 1991

By Hans von Michaelis

It is appropriate that this opening session of HAZPAC '91 and Randol Gold Forum CAIRNS '91 should address the question of what the two industries can learn from each other. The panel is made up of members with experience in both industry. Several are experts on managing both hazardous waste and the mine/mineral processing environment. There is a marked difference in the regulatory needs with respect to treating and disposing of mining and mineral processing wastes, and "hazardous" or industrial waste materials. The topic of this paper is on the things that the two industries have in common: Many of the processes and technologies that are being used or are currently being developed for treatment of hazardous waste are the same or similar to the processes that have been used for decades or k,nger in the mineral processing industry. Hazardous waste treatment and remediation of contaminated solid and/or groundwater is a relatively new industry. Many of the practitioners in this new industry are relatively inexperienced in most of the "new" technologies that are being applied or developed.

Jan 1, 1991

By Ehsan Alavi, Daniel Cressman, Tatiana Chiesa, Robert Mayberry

The City of Toronto’s Coxwell Bypass Tunnel (CBT) is currently being constructed by North Tunnel Constructors ULC. The scope of the CBT project includes construction of approximately 10.5 km of 6.3 meter finished diameter rock tunnel, five large diameter (20 and 22 meter) storage shafts and eleven tunnel connection drop shafts, along with associated deaeration and adit tunnels. This paper describes progress on the CBT to date and reviews the approach taken in both design and construction of the tunnels and shafts to mitigate risks and reduce cost and schedule of construction.

Jun 13, 2021

By Camilo Quintero, Frank Cesario, John Kinnear, Brian Boye

In this paper, an innovative approach was adopted to automatically calculate the effects of tunnel induced settlement on buildings and utilities. The approach resulted in increased output quality, consistency, reduced time, cost savings and a greater ability to respond quickly to design changes. The techniques described have been applied to the Fairbank Silverthorn Storm Trunk Sewer System project, located within the City of Toronto. The automation allowed a very large area of topography, tunnels (6 km), buildings (9000) and utilities (over 1000) to be rapidly evaluated. Visualization of the settlements and impacts also allowed the project design team to optimize the system design to mitigate the settlement impacts.

Jun 13, 2021

By P Cochrane

Our ability to generate information and transport it about the planet on super highways of optical fibre is about to change the way in which we communicate, work and live. There is not a single aspect of our future that will go untouched by the communication and computing revolution that Is now upon us. The change we are about to witness will overshadow the impact of the printed word, industrial revolution and physical transport. The next major wave of information technology (TT) development will focus on the delivery of information and experience on demand, in the right form, at the right time, at the right price, to fixed or mobile terminals anywhere, over networks of optical fibre, radio, satellite and optical wireless. Bandwidth, distance and time will no longer be significant cost elements as service and access become dominant.

Jan 7, 1996

By Dafydd Chandler, Milissa Hirst, Charles Hurst, Gary Snyder, Leszek Glodkowski

The Delaware County Regional Water Quality Control Authority (DELCORA) will be adding tunnel infrastructure to its wastewater conveyance system. This program involves the construction of a conveyance/storage tunnel and related facilities. The proposed 12- foot to 14-foot (±) finished diameter, TBM mined deep rock tunnel spans over 8.5 miles and lies approximately 80 ft-120 ft below the surface. The system is connected to the surface by at least five vertical online shafts and one offline shaft with associated 800ft long adit. This paper provides project details including data on the geologic conditions in which the tunnel will be constructed.

Dec 1, 2022

By Brad Grothen

What is the most economical way of tunneling in mixed ground that may experience high pressures? Non-continuously pressurized, mixed ground Tunnel Boring Machines (TBMs) are being utilized to deal with a wide range of geology. Continuous improvements in these mixed ground machines allow for ever-increasing efficiency and reduction of project risk due to unexpected conditions. We will explore the performance of recent mixed ground machines throughout the world and then look at how new improvements to mixed ground machines will enable excavation of an expanded range of ground conditions. These conditions include mixed ground with low fines, mixed face rock, and fracture/fault zones with high pressures where in the past a Slurry TBM may have been utilized.

Dec 1, 2022

By P. Danson, D. A. White, S. Bashir

Composite ion exchange materials made of SnO2, TiO2 and MnO2 can be used to remove radioactive contaminants from nuclear waste streams. In several cases their selectivity and capacity are enhanced by mixing hydrous silica into the matrix. MnO2-SiO2 materials are especially useful for a number of reasons, such as their selection of heavy elements over caesium. Distribution constants and determinations of exchange capacities show that in many instances the properties of the composites are better than those of the oxides alone, while the presence of a chelating agent has been found to reduce the uptake of nuclides considerably. Methods are being developed for the bulk manufacture of the materials. Further work on sorption mechanisms is required to explain anomalous results, particularly the variation in exchange capacity for different elements and the ability of the oxides to sorb colloidal material in alkaline solution.

Jan 8, 1992

By Maryam Motamed, Jeremy Stone, Leigh Anne Zhang

Controlling and predicting ground movements are essential to the design of shoring systems. The Courthouse Commons tunnel in San Diego, California, included a 56-foot-deep temporary shaft as a launching point for tunneling using the Sequential Excavation Method (SEM). The rectangular shaft was unique in that it was surcharged on one wall by an 11-story building and employed a hybrid support of excavation design. An array of geotechnical instrumentation was used to monitor lateral and vertical movements at the ground surface. This paper compares the measured ground movement with the predicted ground movement from various excavation stages

Dec 1, 2022

By Jürg Künzle

Underground construction is a matter of dealing with the inherent uncertainty of subsurface geology. If the encountered conditions are less favorable than the expected ones, the execution of excavation, support, ground treatment or lining works is likely to require more or different efforts than anticipated, thereby delaying the works and increasing the costs. The 2019 first edition of the FIDIC Emerald Book model contract (FEB) addresses many of the issues to which underground works give rise, including those related to differing site conditions (DSC). This paper examines how under the FEB disputes arising from or in connection with DSC could or should be avoided.

Jun 13, 2021

By Ali Hashemi, Anna P. Perry

The PQ Deeps (PQD) is a production zone located at Newmont’s Musselwhite Mine in northern Ontario. Development started for the PQD in late 2017, and the first stopes were mined starting in early 2021. Unlike most historic longitudinal stoping of narrower orebodies at Musselwhite, the PQD is a wider orebody following the plunge of a fold hinge and is extracted primarily by transverse stoping. Some geotechnical challenges were experienced during early stoping efforts, necessitating design changes throughout late 2021 and early 2022 to optimize the stope design. This work describes the mining methods and design changes to transverse PQD stoping based on geotechnical lessons learned during early stoping efforts.

Jan 1, 2023

By W. S. Fyfe, G. V. Albino, Ekawat Sitthithaworn

The mineralisation is associated with a composite diorite to quartz monzonite stock of Permian to Triassic age that intrudes Devonian carbonate strata. In the intrusive rocks it is associated with potassic alteration and in the carbonate wall rocks it is hosted by prograde garnet-rich and retrograde epidote-rich skarn. Both porphyry and skarn mineralisation include disseminated and fracture-controlled mineralisation, the latter probably accounting for the major part of the contained minerals. Copper, gold, silver and zinc are strongly positively correlated within the mineralised zones, although there are small differences in metal ratios between the different ore types; molybdenum appears to be negatively correlated with copper and gold. Ore minerals include chalcopyrite, magnetite and pyrite in porphyry-type mineralisation and bornite, chalcopyrite, pyrite, magnetite and lesser haematite in skarn.

Jan 12, 1993

By George Schmitt, Ted Dowey, Grant Millener, Sean McAndrew, Eric Jordan

The Rondout-West Branch Bypass Tunnel is being built to bypass a substantial leak in New York City’s primary water supply tunnel. The 13,500 foot long tunnel travels 600 feet under the Hudson River through the same troubled geology and high pressure water inflows that the original tunnel did in the 1940s. A Robbins TBM traversed this geology and built gasketed segments. Nine thousand two hundred feet of 16 foot diameter interliner was installed and backfilled within the segments. Finally, reinforced cast in place lining was placed. This paper addresses the challenges and the multi-tasking approach the contractor utilized.

Jun 13, 2021

By M J. Thomson, P T. Burgin

The economic growth of Hong Kong and adjacent territories in Southern China is, to a considerable extent, dependant on air transportation, but the present Kai Tak Airport is incapable of expansion to meet future needs. After years of study, agreement was reached to build a new airport on the island of Chek Lap Kok, some 34 km remote from Hong Kong, with an ultimate capacity of 87M passengers and 8.9 Ml of cargo per annum. Apart from the building of the airport and its associated infrastructure (including a new town), other similar massive construction works have been necessary in the form of land reclamation from the sea and existing outer lying islands. The construction of bridges, tunnels, railways and highways are also an integral part of the project. The paper provides a broad overview of the concepts of the scheme (called The Airport Core Programme) and highlights some of the major operations and equipment being used in the projects, whose cost at 1992 prices was reckoned to he Hong Kong (HR)$l63hn.

Jan 7, 1997

By NA NA

Hausherr UK Limited Win Order from Italian Cement company Cementerie Di Sardengnu SpA, Qualler Hall complete head gear switch in three weeks, Chief Mins Inspector 'cautiosly optimistic' on safety standards at Privatised Pits.

Jan 11, 1996

By Robert Gordon, Leduar Ramayo

This paper reviews the application of the magnetotellurics method for deep earth imaging, specifically its recent use to better understand original mineral emplacement processes. Resistivity information from newer innovative applications of the technology for nearer surface imaging also provides valuable insights into near surface structure, which in some cases has led directly to new discoveries.

May 10, 2023

By Rafael Ramos, Leonel Quispe, César Chávez

El programa de trabajo de campo realizado consistió principalmente en el cartografiado de la concesión minera EMADSUR I y el muestreo de estructuras (vetas y cuerpos). Los resultados preliminares del estudio geológico en el proyecto Livitaca confirmaron la presencia de mineralización tipo skarn y tipo pórfido de Cu-Mo-Au con diseminación de sulfuros rodeado de un amplio halo de alteración fílica-argílica. Vetas angostas, principalmente entorno de los cuerpos de skarn, tienen contenidos elevados de Au-Cu-Pb-Ag.

May 10, 2023

By Evan Brinkerhoff, Steve Chorley

The largest hard rock TBM ever to bore in the USA, an 11.6 m diameter Robbins Main Beam TBM, recently underwent a planned in-tunnel diameter change to a more compact 9.9 meters. The first-of-itskind conversion process for the Main Beam TBM was undertaken 2.8 km into the bore and was not done inside a shaft or pre-excavated portal. This paper will detail the unique dual-diameter machine designed for the Mill Creek Drainage Relief Tunnel in Dallas, Texas, USA, machine performance, and successful size conversion process that took place in early 2021—a process that utilized the four C’s of construction to enormous benefit: Communication, Cooperation, Collaboration and Coordination.

Dec 1, 2022

By John D. Hanifin, C. Kevin Moon, Eric C. Wang

Value Engineering on Connecticut DOT’s Walk Bridge selected the trenchless option for utility relocation to address the channel crossing’s environmental concerns. The design and construction considerations of the twin micro-tunnel drives and associated shafts are presented. Key challenges included vertical alignment selection to achieve minimum one-tunnel diameter stable cover within thin glacial till underlying extremely soft clay, limited choice of pipe and joint materials meeting stringent non-metallic conduit requirements, thermal grout backfill application, and the close proximity of temporary trestle piles. Mitigation measures were developed for potential point loading pipe damage from remnant boulder fragments in the annular space.

Dec 1, 2022