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By Lindsey Schneider, Steve Kirk, Michael Miglioretti, Jeffrey P. Kolzow, Kyle White

The US17 Spring/Fishburne Drainage Improvements Project utilizes a stormwater conveyance tunnel system of approximately 8,250 LF. The tunnel system includes two intersecting tunnels of differing diameter at a 40-degree angle. The intersection was constructed in soft-ground conditions. This paper discusses the design, geotechnical concerns, initial ground support, and final lining construction. The tunnels utilized two soft-ground TBMs excavated at 15 ft and 11 ft with ribs & lagging initial support. The final lining consisted of unreinforced and reinforced cast-in-place concrete with polymer fibers. Concrete final lining was successfully completed in March 2020.

Jun 13, 2021

By F. Dong, F. Yang, J. Wang, Z. Wang, D. Mingxia

Antimony oxide ores are important antimony resources, but their recovery is still a problem. In this paper, the adsorption behaviour and mechanism of dodecamine and quaternary ammonium salt on the surface of cervantite and quartz were investigated. The flotation behaviour of cervantite and quartz using quaternary ammonium salts and dodecylamine as collectors was studied by single mineral flotation experiments. The adsorbed amount was measured and infrared spectroscopy was used to study the ability of several cationic collectors to float cervantite and quartz. The results show that quaternary ammonium salts can simultaneously float the cervantite and quartz. It is difficult to achieve separation of the two minerals using quaternary ammonium salts as collectors. At pH>10, dodecylamine can float quartz but not cervantite, which can achieve reverse flotation separation of the two minerals. The difference between the abilities of quaternary ammonium salts and dodecylamine to float cervantite and quartz lies in the different ionisation properties of the two reagents. Quaternary ammonium salt is a strong electrolyte that is completely ionised in the pulp and exists mainly in the form of quaternary ammonium ions. Dodecylamine is a weak electrolyte and predominantly forms molecules under alkaline conditions. Keywords: Cervantite, quartz, dodecylamine, quaternary ammonium salts, flotation

Jan 1, 2020

By E. H., Edwerd H. Robie

WILLIAM CHURCH was one of the founders and the first president of the Detroit Copper Mining Co. and was the first man to interest the Phelps Dodge company in the possibilities of the Morenci district, in the '70's. One rather interesting story concerning him is told by James Colquhoun, at one time president of the Arizona Copper Co., in his "History of the Clifton-Morenci Mining District." It seems that a geologist visited the Detroit company's mines and gave Alec McLean, then mine superintendent, quite a lesson on the proper mineralogical terms for what he saw in passing. Later, McLean handed out a few of them to Mr. Church as they walked through the mine on a tour of inspection. The latter had even less regard for a geologist than he did for sulphide ore, which meant little indeed, for in those days the rich ore was all oxidized, and there was no money in the sulphides. So Church was completely unimpressed by the geological and mineralogical terms that McLean had acquired from the visiting geologist. Church turned on him and warned him that so long as he was a member of his staff he was to understand that there were only two kinds of rock in his mines-the one was smelting ore and the other was waste rock, and he was not to forget it.

Jan 1, 1942

By H. E. Pawson

Giant Yellowknife is located 600 air miles north of Edmonton on the north shore of Great Slave Lake in the Northwest Territories. In its 24 years of operation some 7,730,000 tons of ore have been treated to yield $175,000,000 worth of gold.The gold ore occurs at irregular intervals throughout a fold-like sericite schist zone cutting Precambrian rocks. The ore is characterized by 40 to 80% quartz - carbonate and about 10% pyrite and arsenopyrite. Considerable amounts of stibnite and antimony sulpho-salts are also present. Gold is finely divided in the native state existing in complex association with the sulphides. In most instances stibnite is barren but minor values are evident on occasion. Visible native Fold, quite prevalent in the early operating years, is, practically non-existent today. It was readily apparent from mineral dressing investigations conducted in .1944 that Giant ore would be difficult to treat. By 1948 a flow sheet had been established and operations began. In the ensuing years, changing ore characteristics necessitated modifications to some process steps and complete abandonment of others. By 1962 the major metallurgical problems were solved and all that remained was the refining of operating performance to its highest level.With one or two exceptions today's operation follows the practice established by 1962 (Fig. 1 - Flowsheet).

Jan 1, 1973

By Verya Nasri, Mehdi Bakhshi

"Fiber reinforcement has emerged as an alternative to steel bars in precast concrete segments due to advantages such as saving cost and reducing production time while developing a more robust product with improved handling and long-term durability. ACI recently drafted a new report as the first design guideline on FRC tunnel segments to provide specific guidance for this emerging technology. ACI document offers general information on the history of FRC precast segments from tunneling projects throughout the world; a procedure for structural analysis and design based on governing load cases, and a description of the material parameters, tests and analyses required to complete the design. This paper summarizes the design considerations in this ACI guideline prepared by the authors of this paper as the main contributors. Application of this guideline to design of a tunnel with an internal diameter of 5.5 m (18 ft) results in elimination of steel bars.INTRODUCTIONPrecast concrete segments are installed to support the tunnel excavation behind the Tunnel Boring Machine (TBM) in soft ground and weak rock applications. The TBM advances by thrusting off the completed rings of precast concrete segments that provide both the initial and final ground support as part of a one-pass lining system. These segments are typically designed to resist the permanent loads from the ground and groundwater as well as the temporary loads from production, transportation and construction. Tunnel segments are generally reinforced to resist the tensile stresses at both the Serviceability (SLS) and the Ultimate Limit States (ULS). With traditional rebar, a significant amount of labor is needed to assemble the cages and place the rebar, which results in higher production costs.Fiber Reinforced Concrete (FRC) can be used to enhance the production, handling, and placement of precast concrete segments. This is because of the uniform dispersion of fibers throughout the segment to include the concrete cover, which is very advantageous for resisting the bursting and spalling stresses. These stresses develop as a result of the high loads induced on the segments during the TBM jacking process. The presence of fiber in the concrete matrix helps mitigate against unintentional impact loads during segment handling and tunnel construction operations."

Jan 1, 2016

By A Bax, G Wardell-Johnson, W P. Staunton, J McGrath, J J. Eksteen

Since 2001, the AMIRA P420 gold processing technology project series has been studying the recovery of gold using gravity devices, with particular emphasis on the centrifugal units, Knelson and Falcon concentrators. The work has entailed the surveying of operating gravity circuits in Australia, Africa and North and South America.This paper reviews some of the results and lessons of these studies, including common circuit operating and design factors, which limit gravity recovery; pointers towards effective modelling of gravity circuits; and the contribution of gravity to overall gold recovery.CITATION:Wardell-Johnson, G, Bax, A, Staunton, W P, McGrath, J and Eksteen, J J, 2013. A decade of gravity gold recovery, in Proceedings World Gold 2013 , pp 225-232 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By W. A. Jankola, M. T. Martin

"The world's first zinc pressure leaching plant at Cominco's Trail operations started production in 1981. Sullivan zinc concentrate is leached at the rate of 190 tpd in a four-compartment autoclave at elevated temperatures and oxygen pressures to produce a zinc sulphate solution and elemental sulphur. Zinc extraction exceeds 98% and sulphide to elemental sulphur conversion exceeds 95%.The sulphur is recovered from the discharged slurry in the underflow of a hydrocyclone, and is upgraded as a flotation concentrate. The concentrate is dewatered, melted and filtered to produce a polished sulphur product of better than 99% purity. An alternative sulphur recovery process employs an unique sulphur separation method that recovers over 90% of the sulphur in the molten state. The remaining sulphur is recovered by flotation following flash discharge of the slurry. The product slurry containing the zinc sulphate solution and the iron-lead residue joins the existing roast-leach zinc plant for purification and zinc electrowinning.IntroductionIn 1981, Cominco Ltd. commissioned the world's first commercial zinc pressure leaching plant at their Trail operations in British Columbia. As part of a $700 million modernization and expansion program for lead and zinc started in 1977, the company installed the first o f two autoclave trains.Prior to pressure leaching, zinc production was closely tied to acid and fertilizer production. Sulphur dioxide produced from roasting the concentrates had to be converted to sulphuric acid. Thus, any expansion of zinc operations with the roast-leach technology would have required extensive modifications to the acid and fertilizer plants as well as to the roasters. Zinc pressure leaching, on the other hand, offered a one-step dissolution of zinc from the concentrates with high extraction, and production of elemental sulphur. The associated dust and sulphur dioxide generated in the roasting process are both eliminated from the working environment of the pressure leach facility. The flexibility allowed by producing elemental sulphur, and the opportunity to break the sulphuric acid link for about 25 per cent of the targeted 272,000 tonnes per year zinc production was very appealing. The process was successfully demonstrated at a pilot plant in 1977(1-6)."

Jan 1, 1985

By A Kobzev, C Robben

Sensor-based particle sorting of gold ores is the masterclass of preconcentration. The technical challenges of a grade in ppm scale makes a direct detection with currently available technology in milliseconds impossible. Consequently, the detection and classification of particles into ore and waste classes relies on detectable proxies which are the foundation for the classification. These must be reliable and repeatable across the ore bodies processed in future. A sensor-based particle ore sorting equipment must therefore be calibrated systematically by understanding the gold deportation in different lithological groups. Also, it must be in best operational state to minimise possible misplacement. The technical challenges are met by a stringent financial regime governing the business case. Many gold ore sorting projects require a stable grade of gold in the rejected waste significantly below 1gr/t. Two examples are introduced in this paper:  The pilot results and operational experience of X-ray transmission (XRT)-based particle ore sorting for pebble sorting of sulphide associated ore;  Laser-based particle ore sorting for pebble circuit of an orogenic, quartz associated gold ore. Usually, sensor-based particle sorters are installed in the crushing section of a plant. However, for large capacity plants, the number of equipment required, and the associated material handling costs result in significant capital and operating expenses for plants with 1200tph run-of-mine capacity. As a conclusion, it was decided to investigate sensor-based particle ore sorting applied to the pebble stream of two existing semi autogenous mills.

Nov 10, 2020

By D. T. Jordan, L. C. Coetzee, G. Kalenga, T. Mahlangu, W. J. Shipman

Although online free cyanide analysers are widely available and used in gold leaching operations worldwide, reliable automated free cyanide concentration control is not consistently achieved in many of these operations. Effective cyanide concentration control is complex owing to amongst others, the long residence times and ore feed variations. Model Predictive Control (MPC) has been proven to provide superior cyanide concentration control over traditional proportional-integral-derivative (PID) control, leading to savings in operational costs and reduced leachable gold losses. In the first example reported in this paper, MPC has improved control of the free cyanide concentration by keeping it within the required range 73% of the time during testing, compared to the previous PID controller that only achieved this target 30% of the time. This represents a 143% improvement. Another example demonstrates a 22% reduction in cyanide usage as a result of using MPC. MPC functionality is rarely available on the programmable logic controllers (PLCs) and control systems installed at gold plants, hence it is implemented on a personal computer (PC) networked to the cyanide analyser and plant infrastructure. Mintek has developed an embedded MPC that installs into the Mintek Cynoprobe analyser, adding MPC functionality without the need for additional PC and network infrastructure, reducing installation costs. This allows plants to minimise their expenditure on additional infrastructure while gaining the benefits of superior MPC technology for multiple cyanide dosage points. This paper will present results showing that the embedded MPC performs as well as Mintek’s existing PC-based StarCS MPC controller, making it a viable alternative for infrastructure-constrained gold plants. Keywords: Model predictive control, gold cyanidation

Jan 1, 2020

By Silvia Misk, Cristina Araújo, João Felipe Costa, Roberto Rolo

Linear estimation methods are widely used for resource evaluation. Among the existing linear estimation methods, ordinary Kriging (OK) was accepted as the best estimator to determine the average ore grade of each block. However, OK is inadequate for modeling small blocks in relation to data spacing, resulting in over-smoothed models. In this study, the results of the recoverable resource from the short-term model are compared to estimated models generated by the traditional method, i.e., OK, and non-linear methods. The conclusion is that non-linear methods improve the accuracy and precision of the long-term model when compared to the model generated by OK.

Jun 25, 2023

By R. Kuyvenhoven, A. Parbhakar-Fox, X. Prieto, J. Quevedo, L. V. Danyushevsky

This paper presents the results of a study focussed on determining the distribution of cobalt in different types of pyrite of the La Estrella IOCG deposit in Chile. In the IOCG mineral deposits, where copper is the main product, the quantification and distribution of cobalt is required to correctly define the technical and economic viability of recovering cobalt as a by-product. In the La Estrella mineral deposit, seven alteration and mineralisation events were recognised through both optical and automated electronic mineralogical analysis. Of these seven events, five different types of pyrites were identified, each with unique characteristics of the pyrite crystals. Through advanced elemental analysis of these five types of pyrites, it was determined that the concentration and distribution of cobalt within the pyrite crystal is dependent on the mineralisation event. The results indicate high cobalt concentrations in the early pyrite mineralisation events, associated with relatively fine pyrite grains, and cobalt generally occurring in a solid form in the pyrite core. The late pyrite mineralisation event exhibits the lowest concentrations of cobalt, with cobalt predominantly present along the outer periphery of the pyrite. These results are relevant from a metallurgical point of view because the preferential location of cobalt within the pyrite crystal will influence the maximum metallurgical recovery of cobalt. For this, a cobaltiferous pyrite concentrate must be formed which, according to the characteristics of pyrite, must be processed with the optimal solubilisation method. The overall objective is to ensure both good cobalt recovery and a high concentration of cobalt in the leach solution resulting from pyrite leaching. Keywords: Cobalt, pyrite, IOCG, copper, metallurgical recovery, solubilisation, Chile

Jan 1, 2020

By T. Gupta, T. Ghosh

Rare earth elements (REEs) and their compounds are essential in a multitude of mundane and sophisticated applications such as renewable energy technologies, catalysts, medicine, and defense applications. The global supply deficit could be attributed to the destabilization of REE market that has, as a result, incentivized indigenous production of REEs. Cost-effective and environmentally benign opportunities are being explored for the production of REEs from non-conventional mineral sources including coal and coal by-products to stabilize the supply chain. Coal from Healy coal mine and Wishbone Hill deposits in Alaska have been quantified for REEs and were found to possess elevated total REE concentrations as compared to world average levels (60– 70 ppm). The objective of the study was to concentrate the REEs in the froth phase by froth-flotation of the fine size fraction (< 75 μm). A Box-Behnken design of experiment was employed to ascertain the main and interaction effects of operational parameters on response variable by analyzing 3D response surfaces. Experiments were carried out to maximize REE recovery and concentration by modeling and optimization of three operating variables (frother dosage, pulp density (% solids), and collector dosage). Based on the results, the optimum flotation conditions for maximum recovery at an elevated concentration of REEs in the froth fraction was obtained at 4.2% solids and 32.7 ppm of frother dosage for Healy sample and 10% solids and 37.9 ppm of frother dosage for Wishbone Hill coal sample. The quadratic relationship between the input and response variable was found to be independent of collector dosage suggesting good surface hydrophobicity and floatability of the two coal samples.

By D David

The development of Western Australian magnetite deposits has lead to the design of some of the largest grinding mills and plants in the world. One of the projects demonstrates the efficiency gains possible by developing a simple yet thorough test program for circuit design. By drawing on the experience of current magnetite operations in Australia and the Mesabi and Marquette iron ranges in the United States, a basic flowsheet was developed. Through comprehensive testwork with AG, ball and stirred milling the flowsheet was optimized to take full advantage of each grinding mill’s strengths to reach the required final grind size. Laboratory work was verified in the pilot plant to optimize the energy efficiency of each grinding step while ensuring adequate liberation at each step for sufficient gangue rejection. By using three stages of grinding, the ball mill can best be employed in ensuring all top size gangue material is liberated and removed in the second magnetic separation step. The inclusion of the IsaMill, with its inherent steep product size distribution, as the tertiary grinding stage ensured that maximum grade was achieved and simplified the downstream process while giving further improvements in total grinding capital and operating costs. In this way the combination of the two technologies downstream from the AG mill is far more efficient than either would be on its own by reducing the total installed power by 1/3 and annual grinding media cost by 2/3.

Aug 8, 2011

By Z. D. Hora

Commercial production of barite commenced in British Columbia in 1940; shipments have been recorded from ten deposits, of which four are particularly significant: The Brisco, Silver Giant, Parson, and Mineral King mines. Parr of the barite production is a by-product of base metal deposits in which barite is a major gangue mineral. About one hundred occurrences are known. COMMERCIAL production of barite in British Columbia dates back to 1940. Production volumes rose and fell and reached 39,900 tonnes in 1972. The main producer is Mountain Minerals Limited . There are two principal areas of barite deposits in British Columbia: ( I) The southeast part of the province along the Rocky Mountain Trench , which is the source of all production to date. (2) Stratabound occurrences in northeast British Columbia in the Gataga-Ketchika rivers and Muncho Lake areas which are not yet developed. Of the approximately one hundred reported barite occurrences, only ten have recorded commercial shipments, some of insignificant amount. So far, four deposits have proved to be important producers: Brisco, Silver Giant, Parson and Mineral King. The Mineral King property is situated near the confluence of Toby and Jumbo Creeks, 35 km southwest of lnvermere. The lead-zinc-copper-iron-barite deposits, as described by Fyles (1959, 1962), replace Proterozoic Mount Nelson dolomites of the Purcell system on the limb in the trough of a complex, tight syncline. The mine operated from 1954 to 1967 and 2,097,900 tonnes of baritic ore that was processed for base metal concentrates and also produced 22,680 tonnes of by-product barite. Since 1970, some 136,000 tonnes of barite have been recovered from the old tailings pond. The deposit is now considered depleted. The Silver Giant mine is located 10 km northwest of Spillimacheen. Barite and lead-zinc sulphides replace Cambrian Jubilee limestone near their contact with the overlying Ordovician McKay slate. Mineralization is located in the nose of an overturned plunging anticline. Between 1951 and 1957 800,000 tonnes of baritic ore were processed for lead and zinc concentrate. After 1959 barite was also produced , first from open pit, and later from reworked tailings. Up to 1979 production of barite totalled approximately 180,000 tonnes. Two other producing mines in the area are descri bed by G.R. Manson (this volume). Large, bedded stratabound barite deposits are reported from northeastern British Columbia. Six major shale-hosted Industrial Minerals in Canada lead-zinc-barite occurrences are known in the Devonian Gunsteel Formation. These are: Driftpi le Creek, Mount Alcock, Cirque, Pie, Fluke and Elf. In addition, numerous occurrences of strati form blebby or nodular barite and locally massive white crystalline barite are known from the Driftpi le Creek and Ak ie River districts in Gunsteel shale and from the Kechika, Road River and Ware map areas from Silurian siltstone . The size of these deposits is impressive; the baritic horizon at Mount Alcock is reported to be 25 to 30 m thick , and dri ll ing results from the Cirque deposit indicate reserves of 30 mi llion tonnes of baritic lead-zi nc-si lver ore. Similar bedded barite deposits are also reported from Midway area, near the Yukon border.

Jan 1, 1984

This review provides a new and comprehensive summary on studying colloidal interactions encountered in mineral processing with representative examples for critical information, which are of great scientific and practical importance. Colloidal interactions play a vital role in mineral processing, including grinding, physical separation (particularly flotation), dewatering and tailings management (Fig. 1). Despite great energy input in comminution to liberate valuables from gangues, hetero-coagulation between valuables and gangues would prevent the separation of valuables from gangues. On the other hand, selective coagulation/flocculation to increase the size of desired fine particles could enhance physical separation and dewatering, while dispersion is needed for fine grinding. The importance of colloidal interactions is becoming increasingly significant as we process ever more finely disseminated low-grade ores as a result of inevitable depletion of high-grade ore deposits. To control the state of colloidal dispersions by creating favorable conditions, it is of paramount importance to study colloidal interactions in a relevant system and understand underlying mechanisms. 

In November 1999 Waihi Gold Mining Company commissioned its new crushing and conveying plant used to transport both ore and waste from the Martha Mine to its ore processing plant and also its tailings dam construction area. To date, a record monthly throughput of 854 000 tonnes throughput has been achieved. This paper outlines the measures taken subsequent to the commissioning of the system to achieve greater than design throughput and to mitigate the environmental and safety issues associated with operating the system in the middle of a town.

Jan 1, 2001

By Dennis J. Callaghan

This report is the result of information obtained from a review of related literature, personal inquiry and on-site examination of active surface coal mining operations. Four improved surface coal mine systems are described in detail and evaluated for feasibility, implementation requirements, environmental benefit and costs. Engineering feasibility emphasizes equipment availability, compliance to design requirements, practicality and industry rating. Implementation potential emphasizes immediacy, ease, acceptability and constraints. Special attention was given to environmental responsiveness, both with regard to the solutions to mined-land reclamation problems and to the concurrency of reclamation. Each system description includes a hypothetical model mine with a depreciation schedule, capital summary, estimated annual production costs, sales price computation, production and operating cost summary, and a sensitivity analysis of mine price to stripping ratio. A program plan and time schedule for demonstrating a selected mining system covers site selection criteria, mine data collection, criteria for controlling and budgeting costs and reporting findings. Ten additional mining methods and techniques are briefly described and evaluated. Common reclamation problems are listed and described. Sixteen state reclamation laws and regulations are abstracted. Sixty-nine references are listed in the bibliography.

Jan 1, 1976

The contractor examined L.T. White&apos;s Patent No. 3524680 and, finding it in need of engineering refinements, proceeded with a conceptual design of a variable wall mining machine. The contractor then proceeded to assess the feasibility of the variable wall mining machine measured against the criteria specified by the U.S. Bureau of Mines. The feasibility was judged from a physical aspect, a health and safety aspect, and an economic aspect. The Variable Wall Mining Machine was judged to be feasible on all three aspects provided that certain specified practices were adopted. Description The specifications and design and performance parameters of the Variable Wall Mining System as conceptualized are summarized in Tables I and II. The system consists of a side-cutting auger operating in a string of identical 12 ft. sections, along a 500 ft. retreating longwall face. In addition to the 41 identical sections, there is a special drive and discharge section at the head gate.

Jan 1, 2012

By Thomas V. Falkie

In bygone days, the mineral engineer spent most of his/her time on the technical aspects of designing, building, and managing mineral operations. In the last few decades, mostly since the 1960s, increasing amounts of engineering man power and time are spent dealing with federal, state, and local government agencies, laws, and regulations. It is not possible to plan, design, build, or operate mines, mills, smelters, or even office buildings without detailed consideration of government regulations and permitting requirements dealing with environment, worker health and safety, etc. The four chapters of this section provide an overview of the social, legal, political, environmental, and health and safety aspects of mineral enterprise. The section sets the stage for the working engineer/geologist in industry, government, consulting, or academe and points the direction for more detailed study in each of these areas.

Jan 1, 2008

By D. L. Moellenberg

Under various state laws enacted mostly within the last 20 years, reclamation requirements and standards for hard-rock mining operations have been established virtually everywhere in the western United States. Unlike the uniform and detailed coal mine reclamation requirements under the federal Surface Mining Control and Reclamation Act ( "SMCRA" ) and state programs mode led after SMCRA, the various state law hard-rock mine reclamation requirements are based upon a variety of objectives, and therefore are subject to varying standards from state to state. While the diversity of reclamation requirements complicates the determination of what reclamation measures will be required at any particular mine, there are valid reasons for this diversity. There are dozens of different commodities mined in the United States, and mining methods are different for each commodity. Local natural conditions such as climate, precipitation, geology, hydrology, and biology vary widely across the county. Site-specific conditions also affect mining and reclamation methods. Also, factors such as economics, land use, and environmental protection issues receive different priorities in different states and communities within those states. State reclamation requirements in general provide the flexibility to consider site-specific circumstances, allowing operators to design and engineer the best reclamation measures for each mining site. To the mine developer or manager, reclamation requirements must be translated into design, operational, and closure measures for mine planning. Each of these measures must then be assigned additional costs to be factored into the economic decisions for a particular mining operation. On a broader level, reclamation costs must be factored into decisions such as where to invest in exploration and mine development. The purpose of this paper is to provide a summary of the state non-coal mine reclamation requirements in twelve western states. This summary comparison may be useful as a starting point in considering how local reclamation requirements will impact potential mining costs.

Jan 1, 1994