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By Bruno Vingiani, Alessandro Bertero

"The use of Artificial Ground Freezing (AGF) for temporary soil strengthening and seepage control is an effective alternative to grouting when dealing with soils whose degree of finesses would imply the use of highly expensive chemical grouts. However, compared to grouting, the application of this improvement technique usually needs a more accurate preliminary soil investigation campaign and a design assisted by specific calculation software. Besides a general description of the main features of this technique, the paper will describe a recent application of AGF carried out in Rome to underpass an existing metro station.INTRODUCTIONNatural ground freezing occurs seasonally or permanently (permafrost) in some areas of the globe close to the poles and can negatively affect the engineering performance of underground structures. On the other hand, Artificial Ground Freezing (AGF) is man-made controllable freezing process that can be used in foundation engineering to temporarily strengthen the ground and create a barrier to the passage of groundwater. During the process, the heat is extracted from the soil in a cylindrical shape around a number of freezing pipes installed into the ground. This action produces columns of frozen soil, which expand gradually till they merge and create continuous frozen wall. The thickness of this barrier can be regulated according to the specific project requirements. Nowadays, AGF technique is applied to a wide range of foundation engineering problems where soil stability and groundwater flows are an issue (Pimentel et al. 2011, Haß and Schäfers, 2013). Typical applications include the temporary stabilization and waterproof of the ground around the excavation profile of mined tunnels until the construction of the final lining (Figure 1).The case history described in this paper deals with a recent application of AGF carried out during the construction of metro Line “C” in Rome. Specifically, this technique has been applied to allow the construction of two single-track mined tunnels running underneath an existing metro station belonging to Line “A”. In that case, the AGF has been evaluated by the Designers as the only possible solution for improving the mechanical and hydraulic characteristics"

Jan 1, 1900

By Luca Pingue, Regine Jagow-Klaff, Franco Muratore, Carlandrea Albonico, Damiano Frontini, Rudolf Wernecké

This paper describes an artificial ground freezing (AGF) application carried out to ensure both watertightness and structural support for the safe excavation of four cross passages of the Forrestfield Airport Link (FAL) project in Perth. The line will deliver 8.5 km extension of the existing urban rail network connecting the growing eastern suburbs of Perth with the existing suburban rail network. The proposed soil improvement technique is adopted as a smart alternative to jet grouting from the surface since the use of heavy equipment with long vertical mast was not allowed due to the line underpassing an airport in operation. In this paper, details of the challenges and lessons learned during both design and construction phases are given. Furthermore, it is described the geometry and the installation of freeze pipes in presence of a massive steel frame, ventilation system and slurry pipes of the tunnel boring machine (TBM) in operation. It is also illustrated the web monitoring system to allow key personnel to follow in real time the development of soil temperatures, tunnel convergences and ground surface deformations as well as changes in the interaction between international parties involved due to the COVID-19 pandemic.

May 1, 2022

By P Mugebe, M Yahyaei, M S. Kizil, R Low

This paper seeks to establish an empirical relationship between the impact of mining technological innovation implementation and a company’s market value. The company’s market value is represented by its stock price. In a bid to ascertain the relationship, a stock price prediction model is sought to be established using the firm-specific factors impacted by the implementation of innovative technology. This work is performed under the watch of the prevailing macroeconomic factors. The background anchors in the understanding that the difference between the economic status of a mineral deposit and its uneconomic status lies in the level of mining technological innovation most prevalent at a given time (Hartwick, Olewiler and Preuss, 1986; Wellmer and Scholz, 2017; Wright and Czelusta, 2003). This is derived from productivity improvement, resulting in sustainable profitability due to technological innovation. Unfortunately, there is not an adequately established relationship that links this technological innovation impact to the share price performance of the mineral commodity company.

Sep 1, 2024

By Paweł Stefaniak, Natalia Duda-Mróz, Sergii Anufriiev, Wioletta Koperska

Due to the high environmental risks and negative impact of a failure, tailings storage facilities (TSFs) need constant monitoring. Advanced mathematical models have been developed in the past to predict the behavior of TSFs and raise alerts if needed. To be precise and reliable, such models need a spatial distribution of soil types within the dam as an input. Getting this data from laboratory measurements is time and costconsuming. In this article, we propose an ANN-powered algorithm, which allows us to accurately estimate the soil distribution based on a cone penetration test (CPT).

Jun 25, 2023

By Sepideh Javanshir

The process of liquid?liquid extraction of gold from chloride solution is complicated by the presence of many variables acting simultaneously in an unknown non-linear fashion for the determination of the final extraction efficiency. In practice, it is quite difficult to develop a model for predicting various properties of such process. Therefore, an alternative approach based on Artificial Neural Network (ANN) is considered to assist in the simulation process. Artificial neural networks (ANN) are powerful tools that can be used to model and investigate various highly complex and non-linear phenomena. This paper presents application of Multi-Layer Perceptions (MLP) to construct relationship that will be employed to develop a quantitative method for the estimation of the extraction efficiency as a function of hydrodynamical parameters such as stirrer speed, [AuCl4]- and DBC concentration, organic and aqueous flow rate. The model is shown to be in excellent agreement with the experimental data (R2 value for training and testing data was 0.9992 and 0.9915 respectively). Therefore, it can be used to optimize the parameters of liquid?liquid gold extraction with dibutyl carbitol (DBC).

Sep 1, 2012

In longwall mining, premining prediction of methane emission rate depends on a number of geological factors, geographical factors, and operational factors. These same factors also can impact the selection of a specific degasification system. This study proposes a principle component analysis (PCA) and artificial neural network (ANN) approach to predict the ventilation methane emission rates of U.S. longwall mines and the optimum combination of degasification boreholes based on the given characteristics of the mine. Artificial neural networks, more than conventional computer models, are adaptable systems that can solve problems such as non-polynomial or very complex relationships that are difficult to describe mathematically. Data on ventilation emissions and degasification system design were obtained from 63 longwall mines in 10 states and were combined with corresponding geological, geographical, and operational parameters for the period 1985-2005. PCA was used to determine the variables that most influence ventilation emissions and degasification system design. Different combinations of variables in the data set and network structures were used for network training, cross-validation, and testing. The resultant ANN models predicted ventilation methane emissions with a 90-95% accuracy and were superior to multi-linear and second order non-linear models. The ANN-based expert classification system was able to classify the design of the degasification system (no degasification, gob vent borehole, horizontal and gob vent borehole, and horizontal, vertical and gob vent borehole) with more than 80% accuracy. The models can be used as prediction and decision tools for the ventilation emissions and degasification system selection for specific site and mine-design conditions.

Jan 1, 2009

By Daniel Hodouin

Artificial neural networks (ANN) are of growing interest in a wide variety of applications. Pattern recognition, speech processing, financial analysis, signal processing and process control are at present the most successful ones. This paper is an attempt to illustrate the potentiality of ANN applied to mineral processing. An introduction to the technology of ANN is first proposed to describe the various components and to explain the various phases encountered in setting up a network. Then examples are given to illustrate the use of ANN dynamic modelling of mineral processing units or plants and in process control.

Jan 1, 1991

The South Wall Base Case Design for Mt Whaleback indicated that along portion of the South Wall a cigar shaped synclinal keel, contain- ing 14 800 m', of Dales Gorge Member ore, would be unkeyed and bed- ding undercut. The dry "ore lobe" slope would be 60m high, unbenched and approximately 170 m long. Stability analyses using specific design parameters established that artificial reinforcement could stabilise the slope and be economically justifiable. To implement the slope design reinforcement for such a complex geo- logical structure it was necessary that all functions pertaining to slope excavation be integrated and co-ordinated within the Mine Geotechnical Section. The objective being to minimise slope damage and thereby optimise the effect of design reinforcement. The successful excavation of the ore lobe in 1988, three years after the introduction of artificial reinforcement, was achieved by strictly main- taining the following parameters. 1. Accurate Geological Model 2. Controlled Perimeter Blasting 3. Controlled Excavation Techniques 4. Quality control -Reinforcement Installation 5. Additional Reinforcement.

Jan 1, 1989

It is a well known fact that the best method of rock reinforcement is to avoid physical ground support. This goal can be achieved by means of: - Increasing the rock structural strength - Geological definition and forecasting. - Sequencing the excavation - Smooth blasting In many cases however, extra ground support is needed in order to maintain safe working conditions. In an open pit, the structural strength of rock cannot be increased by lowering the pit walls due to economical reasons. Economy demands steeper walls and less waste to be hauled to the dump. The geological conditions can also often be extremely poor and unpredictable. For excavation sequencing and smooth blasting there are good possi- bilities, such as cleaning of the pit walls after the main excavation, arul- ing of long small diameter straight inclined holes, use of smooth blasting techniques and lightened explosives.

Jan 1, 1989

On September 4, 2007, Mine Safety and Health Administration, in alliance with the International Union of Operating Engineers and the International Association of Bridge, Structural, Ornamental, and Reinforcing Iron Workers, presented the first annual Mine Construction Maintenance and Repair?s Safety Contractor of the Year Award to Artisan Contracting, Inc., of Cape Girardeau, MO. Eligible contractors located throughout the United States were nominated. Artisan Contracting was nominated by Illinois Cement Company located in LaSalle, IL. Illinois Cement Company is a Division of Eagle Materials Inc., located in Dallas, Texas. Mr. Larry Frankum President of Artisan Contracting Inc., stated, ?While it is gratifying to receive a wonderful award such as this, we must not forget how fragile a good safety record is. We must constantly remain diligent in pursuit of maintaining safe work sites.?

Feb 1, 2008

By J. Diaz

"Antioquia region, in Colombia, is considered one of the areas with the highest mercury contamination in the world due to its use in gold recovery through artisanal mining, emissions to the environment between 100 and 150 tonnes of mercury are estimated by year. Therefore it became necessary to develop a project in which it was proposed aim to empower traditional artisanal mining community, or in different areas, such as gold mining in the region of Antioquia, in the implementation of safe mining practices and environmentally sustainable, from the introduction of clean technologies, in order to prevent or mitigate the impacts generated by traditional mining on the environment and the communities involved. In order to achieve this training to traditional mining community developed and technical visits to artisanal mining were performed in order to optimize operating processes and promote safe mining practices. In the project more than 1400 artisanal miners were trained.INTRODUCTION In the developing world, a combined 30 million individuals extract more than 30 different minerals using rudimentary techniques. Gold is the preferred mineral extracted by artisanal operators due to its high unit value and its market price, which has increased almost sevenfold over the last decade (Veiga et al, 2014). The artisanal gold mining sector in Colombia has 200,000 miners officially producing 30 tonnes Au/a. In the Northeast of the Department of Antioquia, there are 17 mining towns and between 15,000 and 30,000 artisanal gold miners (M. Veiga, 2010) (Upme, 2014). This production, however, has caused environmental problems, including high levels of river siltation and mercury pollution (Veiga et al, 2014) (UPME, 2007) (Cordy et al., 2013). The mercury contamination in Colombia by artisanal gold mining has been recognized by a number of researchers and local authorities for over a decade estimated that the annual mercury emissions from artisanal gold miners in Colombia in 2007 were between 50 and 100 tonnes, however given recent gold value increases and gold rush activity, current mercury emissions are likely much higher. Colombia is likely the world's 3rd largest source of mercury emissions from AGM after China (240 to 650 tonnes of Hg/a) and Indonesia (130 to 160 tonnes of Hg/a) (Telmer and Veiga, 2008) and is the world's highest per capita mercury polluter (M. Veiga, 2010)."

Jan 1, 2016

By P. Moreno

ABSTRACT: The Maras salt terraces, located between Cuzco and Urubamba in the Andes (southern Peru), are living examples of traditional Incan salt production, where present-day artisanal miners produce salt from shallow pans by solar evaporation. In these terraces, natural spring water, eight to nine times saltier than seawater, is used to produce the salt. The field observations and chemical analyses show that the poorly crystalline traditional salt is finer in particle size and contains impurities such as dolomite and gypsum. These differences are the result of shallow pond depth, contamination from wall erosion, and the nonsequential mode of salt crystallization.

Jan 1, 2011

By B. O. Odera

The Pt-based alloys have a high potential for replacing some Ni-based superalloys (NBSAs) used in the highest temperature and most aggressive environments, and vanadium would be a beneficial alloying element. Six alloys of average compositions Pt-26.6Al-9.1V, Pt-23.1Al-17.8V,Pt-9.6Al-21.1V, Pt-17.4Al-6.4V, Pt-22.3Al-7.9V, and Pt-6.0Al-10.1V (all in at.%) were manufactured by arc-melting and examined in the as-cast condition using scanning electron microscopy and X-ray diffraction (XRD). Five samples were heat treated at 1 000°C for 1 500 hours and water quenched, then examined. The phases were identified using energy-dispersive X-ray spectroscopy and the identities were confirmed by XRD. In most of the samples, the phases existing in the as-cast condition were different from those at 1 000°C after ~1500 hours heat treatment. A solidification projection, an isothermal section and a liquidus surface projection were determined for the Pt-rich corner.

Jan 1, 2012

By B. O. Odera

The Pt-based alloys have a high potential for replacing some Ni-based superalloys (NBSAs) used in the highest temperature and most aggressive environments, and vanadium would be a beneficial alloying element. Six alloys of average compositions Pt-26.6Al-9.1V, Pt-23.1Al-17.8V, Pt-9.6Al-21.1V, Pt-17.4Al-6.4V, Pt-22.3Al-7.9V, and Pt-6.0Al-10.1V (all in at.%) were manufactured by arc-melting and examined in the as-cast condition using scanning electron microscopy and X-ray diffraction (XRD). Five samples were heat treated at 1 000°C for 1 500 hours and water quenched, then examined. The phases were identified using energy-dispersive X-ray spectroscopy and the identities were confirmed by XRD. In most of the samples, the phases existing in the as-cast condition were different from those at 1 000°C after ~1500 hours heat treatment. A solidification projection, an isothermal section and a liquidus surface projection were determined for the Pt-rich corner.

Jan 1, 2012

By Dan Yang

Pile foundation designs are performed routinely based on geotechnical information available at the time of design, often with due consideration of large uncertainties inherent to soils and site conditions. These uncertainties frequently are the causes of piles being installed not the same as those designed, especially by factors beyond quality assurance and quality control. With a variety of both satisfactory and unsatisfactory pile test results from these nonconforming piles, the design engineers are required to examine the foundation performance as a whole against the project design requirements before signing off on them or calling for potentially costly remediation. Over the years, as-built analysis has been a consistent way of dealing with pile non-conformity and damage in our practice, avoiding many construction delays and it is an integral part of our pile foundation design. In this paper, the key elements of an as-built analysis along with several major bridge projects are presented.

Jan 1, 2010

By A. R. Kiani-Rashid

In this paper, the effect of aluminum content on the formation mechanism, volume fraction, morphology and particle size distribution of graphite has been investigated. Addition of aluminum on ductile iron causes some fundamental changes in iron-carbon phase-diagram and as a result, improves the graphite formation during eutectic transformation. The results reveals that aluminum compounds have been formed in the core of graphite nodules, thus aluminum plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminum content also leads to an increase in the number of graphite nodules and a decrease in the nodules size. By using EPMA, the segregation of aluminum and silicon between graphite nodules has been studied

Jan 1, 2010

Asarco's Sacaton unit, located near Casa Grande 45 miles southeast of Phoenix, Arizona, was brought into production in February 1974. Ore reserves are estimated at about 48 million tons at 0. 95% copper. Mineralization of the orebody comprises both sulfides and oxides, with minor amounts of gold and silver. Preproduction stripping of 40 million tons of overburden was accomplished in less than two years. Mining is done at the rate of 9,000 stpd ore with a waste-to-ore ratio of 4.6 to 1. 0. The mine is developed on 40 ft benches, and by 1979 underground block caving methods will be phased into the operation at a depth of 1900 ft. Ore is mined in the pit two shifts per day, seven days per week, and is hauled with 85 ton trucks to the primary crushing plant. Trucks dump their loads into a 165 st capacity pocket equipped with a chain curtain which controls the ore flow to the 6 ft 6 in. wide by 24 ft long (2. 0 m by 7.3 m) vibrating feeder grizzly. Grizzly bars are inclined at a 5º slope on the first half of the 0 feeder and 10 on the last half. Grizzly bars have 6 in. (13 mm) spacings which pass 60 to 70% of the mine-run ore. Grizzly oversize drops into a 48 in. by 60 in. (1. 22 m by 1.52 m) primary jaw crusher. Both the grizzly undersize and crusher discharge are collected on a 42 in. (1.07 m) conveyor belt operating 398 fpm (121 mpm) for transport to the 4,750 live st intermediate storage area ahead of the fine crushing plant. Capacity of the Sacaton primary crushing plant is a nominal 1150 stph (1043 mtph). It operates fourteen shifts per week with an effective crushing time of four hours per shift. An economical open-air design was used, but an enclosed operator control room is located on the upper level where the dump truck, feeder, and crusher can be observed. Oversize rocks are removed from the feeder or crusher by the 10-ton bridge crane. Direct operating costs for this well-designed primary crushing plant, including labor, power, supplies, and maintenance, are only 3.5 cents per short ton. An interesting feature of the Sacaton orebody is that the non-sulfide copper minerals, which are less prevalent than the sulfides, occur intimately with the sulfide minerals; for this reason, all ores as mined are treated in a flotation circuit using sulfidizing methods for oxide recovery.

Jan 1, 1978

By K. Parameswaran, A. Veek, A. Fernandez, P. Safe

ASARCO LLC (Asarco) Hayden Copper smelter, in Hayden, Arizona, has operated continuously (except for minor labor and economic curtailments) since 1912. The current plant configuration comprises INCO flash smelting, Peirce Smith (P-S) converting and fire refining/anode casting. In order to comply with the U.S. Environmental Protection Agency (EPA) 1-hour National Ambient Air Quality Standards (NAAQS) for sulfur dioxide promulgated in June 2010, the Hayden smelter had to increase overall sulfur fixation from approximately 95 % to 99+ %, requiring a retrofit of the existing converter department and upgrade of associated emissions controls systems. The Converter Retrofit Project (CRP) involved replacing the five existing 13’ diameter Peirce-Smith converters (2 blowing, 2 hot standby) with three new 15’ diameter Peirce- Smith converters (1 blowing, 1 hot standby) to allow for more effective process gas capture using the existing acid plant contact section. Significant upgrades were made to the acid plant wet gas cleaning section and converter primary gas handling system to improve capture performance, reliability, and sludge handling. In addition, a new tertiary gas capture system was installed to further minimize fugitive emissions from the converter aisle. The existing furnace tapping ventilation ESP was replaced with a new baghouse to enable at least 50% SO2 removal using high-surface-area dry lime injection, which was also implemented on the existing converter secondary gas baghouse system. The first two converters and all gas handling system improvements were started up in April 2018, and the third converter was brought online in November 2018. This paper presents the regulatory context; genesis and rationale for CRP; detailed description of the project; challenges during commissioning; system improvements implemented, and design considerations made, and systems performance and process optimization achieved since startup.

Jan 1, 2019

By S. A. McGhee

Introduction ASARCO's Ray Operations include an open-pit copper mine in the Mineral Creek Mining District of Pinel County. The district is located in east central Arizona, 132 km (82 miles) southeast of Phoenix, AZ, and 126 km (78 miles) north of Tucson, AZ. The mine lies 8 km (5 miles) north of the Gila River in Mineral Creek Valley, between the Tortilla Mountains to the west and the Dripping Springs Range to the east. The rich copper deposits of the Mineral Creek mining district were first noted by a US Army Officer in 1847. The Ray Copper Company was the first major operation in the area. The company was named after the Ray mining claim, which was one of the earliest recorded claims. After decades of sporadic and unsuccessful mining ventures, the Ray Consolidated Mining Company was formed in 1910. The company introduced one of the first successful block caving operations in the world. In 1933, the Kennecott Copper Corporation acquired the Ray Consolidated Mining Company and continued operation of the mine under the same name until 1943, when the property was renamed the Ray Mines Division of Kennecott. Underground mining continued until 1955, when the mine was converted to an open pit operation. In November 1986, ASARCO Inc. purchased the Ray Mines Division and related facilities from Kennecott. The purchase also included the Hayden concentrator and the Ray Smelter, located approximately 32 km (20 miles) from the Ray Mine. This paper summarizes the 54,400 tpd (60,000 stpd) in-pit crusher and overland-conveying system and the 24,200 tpd (30.000 stpd) copper SAG concentrator and tailings disposal system constructed at ASARCO's Ray Complex - Ray Operations. General description of facilities The Ray concentrator includes a sulfide SAG concentrator, a "relocatable" in-pit primary-crushing plant and overland-conveyor system, a concentrator tailings-disposal system and plant ancillary facilities, The major elements of the project include: • A relocatable Fuller-Traylor in-pit 1524-mm (60-in) x 2261-mm (89-in) primary gyratory crusher at the 442 m (1450 ft) mine elevation. The crushing plant has a nominal capacity of 54,400 tpd (60,000 stpd) of sulfide ore. • A 1524-mm (60-in) wide x 1253-m (4110-ft) long overland belt conveyor, which runs from the in-pit crushing facility to a transfer station serving both the Ray Concentrator and the existing Hayden concentrator railroad load-out facility. • A 1524-mm (60-in) wide x 152-m (500-ft) long stackerbelt conveyor, which delivers a nominal 27,200 tpd (30,000 stpd) of ore from the transfer station to a 23,600 t (26,000 st) live-capacity coarse-ore stockpile serving the Ray Concentrator. • A nominal 27,200-tpd (30,000-stpd) concentrator, including semiautogenous grinding, flotation, copper concentrate filtration and associated plant ancillary facilities. • A tailings disposal system. Flotation tailings are pumped from the Ray Concentrator to a 122-m (400-ft) diam. thickener, located 4.8 km (3 miles) southeast of the Ray Concentrator site. The thickener overflow is pumped to two 76.2-m (250-ft.) diam. concrete process-water reservoirs. The thickener underflow, at 45% solids, is pumped to a new tailings disposal site located at Elder Gulch. • An HDPE-lined temporary-containment area to collect material from Ray Concentrator plant upsets and local storm-water run-off from a 100-year, 24-hour rain event. •A reclaim-water system from the Elder Gulch tailing pond area to the Ray Concentrator. • A 610-mm (24-in.) diam. x 31.9-km (19.2 mile) long fresh-water pipeline from the Hayden fresh-water-well field system to the Ray Concentrator. The overall process design criteria for the new Ray Concentrator is based on a nominal throughput of 27,200 tpd (30,000 stpd) of ore at 90% plant availability. However, based on the maximum performance capacity of the installed grinding equipment, it may be possible to achieve a sustained operating level in excess of 36,300 tpd (40,000 stpd) when processing soft ores. The balance of this paper will cover the major process systems including:

Jan 1, 1995

By P G. Self, M D. Raven, R A. Eggleton

Investigation of an abandoned quarry near Rowland Flat in South Australia identified asbestiform antigorite as the fibrous serpentine mineral mined during the 1940s to 1978 for filler applications, not amphibole asbestos or chrysotile as reported in earlier investigations. Scanning and transmission electron microscopy (SEM and TEM) and selected area electron diffraction (SAED) of individual fibres were used to confirm the identification. Chrysotile is widely regarded as the only asbestos mineral in the serpentine group. Further work was done therefore, on the geology and mineralogy of the occurrence, and the health implications were reviewed. A zone of antigorite alteration, with associated talc, is traceable for 750 m along strike of recrystallised dolomitic siltstone within Woolshed Flat Shale of Neoproterozoic age. The antigorite formed, in part, by replacement of prismatic crystals of probable tremolitic amphibole. The deposit is proximal to the Williamstown Fault and the serpentine-talc alteration is possibly due to fluids expelled along the fault during late-stage deformation in the Early Palaeozoic Delamerian Orogeny. The antigorite comprises white to pale green bundles of lath-shaped fibres that occur either as randomly- arranged equant patches after amphibole or as cross-fibre veins, both intimately mixed with calcite. Highly fibrous product was mined from the weathered zone where calcite was leached during weathering. Gentle grinding releases fibres with a high aspect ratio (>10:1) that show a wide range of fibre thickness, including a significant proportion of fibres <0.25 ¦m width. Toxicological studies on fibrous antigorite from Poland and Italy indicate that the carcinogenic potential of this form of serpentine is similar to amphibole asbestos. X-ray diffraction (XRD) and fourier-transform infrared (FTIR) techniques readily distinguish antigorite from chrysotile. Determination of asbestiform habit and confirmation of antigorite mineralogy is most reliably done using electron microscopy, preferably with SAED capability.

Jan 1, 2008