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By Keat Chuan Chew, Qiao Yue Tung, Teoh Yaw Poh

"1 INTRODUCTION With a land area of 718 square kilometres housing a population of slightly over 5.4 million, as of 2014 (Department of Statistics Singapore 2015), Singapore is a highly urbanised city. Transport infrastructure is critical to keep the country and economy highly connected and functional as the population in Singapore continues to grow. The importance of a robust transport infrastructure is recognised by the Ministry of Transport in Singapore, which is working towards bringing 8 in 10 households within a 10-minute walk of a train station by 2030 (Ministry of Transport 2015). This gives rise to the rapid expansion of the rail network in highly urbanised Singapore, resulting in more tunnelling work having to be carried out in closer proximity to existing buildings. Such tunnelling work is expectedly more challenging and complex, and if not managed effectively, will impose higher risk to the adjacent buildings. Hence, the Building and Construction Authority (BCA) has implemented specific control measures to mitigate such tunnelling risks and to ensure safety of the public. 2 CHALLENGES FACED BY TUNNELLING WORK IN SINGAPORE 2.1 General Challenges of Tunnelling in Singapore With the increasing densification of the rail network in a highly urbanised setting, rail projects in Singapore are faced with several key challenges. One such construction challenge is constrained construction sites brought about by network intensification. Alongside the growth of the rail network, shown in Figure 1, other infrastructure networks in Singapore are also continuously growing. Underground interchange stations between networks become increasingly common, forcing each underground interchange station to be constructed deeper and in closer proximity to existing buildings (Figure 2). Singapore is not alone in facing this issue. The same can be observed in cities like London, in which its myriad network of subway lines pushes new lines and interchange stations to be constructed deeper."

Jan 1, 2016

By S. Eugene Mills

Twenty-five years ago, when I began my sales life marketing minerals, there was little or no contact between sales people and production people. In those days, it was not uncommon for me, as a salesman, to learn of production problems existing in my company from my customers. Today, in my opinion, any successful mining company must keep production people fully aware of circumstances that effect service to the users of the product. Basically, feldspar is presently consumed by the glass and pottery industries the same as 100 years ago. The consuming public little realizes the origin of so many things they use daily and take for granted. Feldspar is utilized in the glass that contains our Coca-Cola, Pepsi, wines, liqueurs, beer and the assorted gob¬lets from which we drink these lovely brews, the industrial glass upon which all industry depends, the bathroom plumbing fixtures that make life so different from the days of the out-house, the beautiful and durable china we enjoy at mealtime. The electricity we use requires insulators that demand feldspar. In our home ap¬pliances, automobiles, toys and airplanes, we find feldspar. I could go on and on, hopefully soliciting your help in making our taxpaying and non-taxpaying fellow man aware of the burdens he may acquire when unthinking, over-enthusiastic environmentalists foist unnecessary hardships upon the mining industry. Feldspar is marketed primarily sized from 20 mesh to 325 mesh. The glass industry requires feldspar ground 20 mesh to 40 mesh size; the pottery industry requires material from 150 mesh to 325 mesh size. One large glass plant may require up to 100 tons per day and more, whereas a small plant may use less than 5 tons per year. A large pottery plant may require as much as 50 tons per day, a small potter only 500 lbs. per year. The feldspar

Jan 1, 1977

By Thomas A. Wilson

Mountain Pass, California is located 96 km southwest of Las Vegas, Nevada, and has an exposed surface orebody within view of Interstate Highway 15. Mineral prospecting in this region dates back to about 1860 followed by the discovery and subsequent mining (1870-1895) of silver bearing veins on the north slope of nearby Clark Mountain. In contrast to the four lane divided interstate highway of today, all supplies needed for mining during this early history were transported by wagons from San Bernardino which is 320 km west. Many small lead mines were active in the area during 1917-20, and a small gold mine operated in 1941-42 within 100 m of the orebody presently being worked. In 1949 two prospectors searching for uranium with a Geiger counter discovered a radioactive vein outcrop at Mountain Pass. Further investigation revealed the presence of a large amount of a light-brown, heavy mineral to a depth of about 2 m. A sample of this unidentified mineral was submitted to the Boulder City, Nevada, U.S. Bureau of Mines where a spectroscope examination shoved high level rare earth oxides, carbon dioxide, and fluorine. These results indicated the mineral was bastnasite.

Jan 1, 1982

By Martial P. Corriveau

The preparation of coal is essentially the same for export as it is for the domestic market. The big difference, I would say, is that, while coal for certain domestic uses (utilities, for instance) need not always be of the highest quality, as long as it is uniform, the buyer of coal for export invariably demands a well-prepared, top-quality product. And he is willing to pay for it, as long as he knows what he is buying. This is where quality control enters the picture. The day is long past since the export market was the dumping ground for coals which could not be sold on the domestic market. Today, the export buyer wants American coals not so much for a price but for the necessity of blending the American coals with foreign coals to achieve the desired chemical and/or physical characteristics, To blend intelligently, he must know in detail what are the qualities of the coals to be blended. Sampling and chemical analysis facilities at the piers provide the information on the coals exported, These facilities are maintained for the export buyer by independent laboratories; however, in one instance, the buyer operates his own laboratory. With very few exceptions, and Clinchfield?s Moss No. 3 mid-volatile coal is one, cargoes shipped overseas are loaded as blends of two or more coals. Up to now, foreign requirements have not been too clearly defined; therefore, shippers must be prepared to blend mixtures of the desired combination. Successful blending requires an accurate knowledge of the coals shipped. And this makes it necessary for the coal producer to maintain his own control laboratory.

Jan 1, 1959

By T. P. Weldum

INTRODUCTION Cleveland-Cliffs' operations in Michigan have been utilizing fully autogenous grinding for over four decades. This is but one of the key characteristics of the iron ore processing method that was developed for the extremely fine grained, low grade deposits of the region. Liberation size of the hematite and magnetite ranges from about 30 to less than 1 micron. Typical grinding fineness target to achieve silica grade in the concentrate is 80 to 90% passing 25 microns, or a P80 of approximately 20 microns. After primary grinding, the magnetite ore is first upgraded by rougher magnetic separation. It is then ground to final product size, sent through thickener-sizers utilizing selective flocculation, upgraded again by finisher magnetic separation, and then brought to final silica grade by reverse amine flotation. Hematite ore follows essentially the same route, less the magnetic separation stages. Concentrate is filtered and pelletized, along with con- trolled additions of fluxstone, to ready it for shipping. Iron ore pellets on the water of the Great Lakes have a value of approximately 1.5 cents per pound. GRINDING PROCESS DESCRIPTION Details of the Empire magnetite grinding process flowsheet have been presented by Greenwood and Rajala (1992), and more recently by Rose et al. (2002). The Tilden comminution process for either magnetite or hematite is essentially identical, with the exception of some variations in the excess pebble treatment methods (McIvor and

Jan 1, 2004

By Kathleen A. Altman

INTRODUCTION The basic premise of the ideas presented in this paper are as follows: Engineers believe that "theoretically" it will work. Operators ask what they must do to make it work. And, people can screw it up. r Today the challenges conf onted during the engineering, startup and operation of mines are becoming more complex. As mining and processing professionals, we are called upon to trav­el all over the world, are subjected to a wide variety of climates and must deal with a numerous cultures and people. Historically, for the majority of the people working in the mining industry, the primary challenges related to projects have focused on the differing perspectives of the disciplines involved. For example, geologists focus on resources and reserves, mining engineers relate to tons or tonnes, metallurgists count ounces or pounds or kilograms of product, mechanics emphasize availabil­ity, human resources personnel deal with absentee rates and turnover and accountants watch the bottom line ($$'s). As the world has become "smaller" and the mining industry has become more globalized, the puzzle is becoming increasingly difficult. Even the most experienced in the crowd of mining profes­sionals are oftentimes surprised by the types of problems that are encountered. Try as we may, we cannot anticipate the complex­ity of dealing with the human side of an operation.

Jan 1, 1998

By Henry Antwi

The decade of the 1990s promises to be one of increasing internationalization for domestic minerals producers as they scramble to enhance relative positions in highly competitive, international minerals markets. This "international mining rush" is fueled by developing countries seeking international investment capital to explore for, develop and exploit sizable mineral endowments in an attempt to support the increasingly popular, but expensive, wave of democracy and selfdetermination sweeping the world. This "fuel" typically takes the form of revised mining codes and, often, lucrative investment incentives. These incentives include favorable tax rates, royalty provisions, relaxation of import/ export constraints, depreciation schedules, profit repatriation and other variables that can positively impact mineral investment decision making. Concomitantly, in their attempts to address real and perceived short- and long-term woes associated with enhancing competitive positions internationally, many domestic explorers and producers are attracted to the prospect of finding high-grade deposits in relatively virgin areas. Combined with the investment incentives provided by foreign governments, these high-grade deposits promise lucrative potential returns from projects having short payback periods. Classic examples of this mutual desire to intensify international mining efforts by domestic producers are illustrated by activity levels in countries like Chile, Bolivia and Venezuela in Latin America and, more recently, in Eastern Europe and select locations in the former Soviet Union. As US corporations scurry to send fact-finding, technical, evaluation and financial teams to these presently popular locations, one area of the world has received little attention - Subsaharan Africa. Specifically, the country of Ghana (formerly the Gold Coast) deserves more attention than it appears to be receiving from North American mining companies.

Jan 1, 1992

By Ammar Henchiri

INTRODUCTION A current need of the phosphate industry is the development of process technology for treatment of high carbonate content ore. About 75 to 80 percent of the world phosphate reserves (1) are associated with carbonate gangue, which is not amenable to treatment by the existing techniques. Numerous laboratory and pilot plant studies have been devoted to carbonate-phosphate separation. Different techniques were involved (washing, sieving, attrition, flotation, calcination, and leaching). For technical and economical considerations, flotation appears to be an efficient process for this problem. Separation of carbonates (calcite and dolomite) from igneous phosphate is applied in industrial plants in Brazil, Finland, and South Africa. But, for sedimentary phosphate, no industrial realization exists at this time, with the possible exception of some plants in China. The main problems with sedimentary phosphates are: • high substitution by CO3-2 and F- for P04 -3 in the apatite lattice. • larger surface area of the phosphate particles because their surface is porous and irregular. • tendency of sedimentary minerals to produce more slimes in conditioning than the crystalline minerals, hence, larger dosages of collectors are required for sedimentary minerals. Investigations reported in the literature indicate that most processes developed for sedimentary carbonate-phosphate separation involved inverse flotation of carbonates using fatty acids as collectors (2), (3) associated with phosphoric acid (4), monosodium phosphate (5), F- (6), or SiF6 -2 (7) as phosphate depressants. Later investigations, conducted by A. Henchiri and G. Baudet (8), (9), (10), (11), (12), (13) in the BRGM technology department, of phosphoric esters revealed that these reagents are selective collectors for carbonate-phosphate separation. The above investigators developed a process which used phosphoric esters to collect carbonate minerals and sulfuric acid or sodium fluorosilicate as depressants for phosphate. Extensive comparative tests for different processes on the same phosphate sample show that the process developed at BRGM is one of the most promising methods proposed for sedimentary phosphate-carbonate separation. It should be pointed out, however, that phosphoric esters make abundant froths. The handling of these excessive froths will be a problem in an industrial-scale plant. This paper outlines test work performed in order to optimize and to improve the efficiency of the flotation process on a sedimentary phosphate ore selected from the Sra Ouertane orebody. The Sra Ouertane flotation process, illustrated on Figure 1, first removes carbonate minerals by inverse flotation and then recovers phosphate as a froth product, leaving quartz as a cell product.

Jan 1, 1993

By Klaus Rieker

"Since the mid-19th century the River Emscher in the German Ruhr District has been used for disposing of wastewater. In the early 1990s, it was decided to replace the existing open wastewater system with a sewer system and to restore the River Emscher to its natural state. The major Emscher conversion project is divided into a large number of individual schemes, with construction phase 30 being the largest. By applying the pipe jacking method, interlinking tunnels with section lengths in excess of 1,100 m are constructed. USAGE OF THE EMSCHER OVER TIME The 85-km long river Emscher flows right through the Ruhr District. It has its source to the east of Dortmund and flows into the river Rhine near Dinslaken (Figure 1).The Emscher has been used to dispose of wastewater since industrialization began about 200 years ago. Intensive coal mining over the years led to considerable subsidence causing stagnant sewer areas which in turn led to typhus and other deceases. Thus in 1899, the Emschergenossenschaft was founded to create an efficient interceptor system for a catchment area of 865 km² through lining, raising and Emschergenossenschaft decided to free the waterways of the Emscher system from sewage and to improve them in ecological terms by 2020. A budget of 4.5 billion euros was earmarked for this purpose.The construction of sewer conduits began in order to no longer transfer the wastewater into the Emscher. The currently ongoing construction of the “Emscher Interceptor” - the main sewer - represents the heart of the Emscher conversion project. The interceptor will run along the river over a length of 51 km. Three pumping stations are required to confine the sewer’s depth to elevations between 15 and a maximum of 40 m below the surface. Since early 2012, the Emscher has been free from wastewater east of the Dortmund-Deusen clarification plant. There are two further clarification plants situated along the Emscher, which treat the still contaminated river water down-stream. Once the Emscher Interceptor is in operation, they will receive wastewater solely from the tunnel system."

Jan 1, 2016

By Juan Ares, Enrique Fernández, Alejandro Sanz, Francisco González

"INTRODUCTION Crossrail is a subsidiary company of Transport for London created for the construction of a new transverse train line 118 km long between Maidenhead and Heathrow in the West, and Shenfield and Abbey Wood in the East, including 21 km underground below London. Crossrail C305 Eastern Running Tunnels project is the biggest contract within Crossrail Project and involved boring 11.8 km of twin tunnels through London’s city center. Crossrail C305 Project interfaced with different contracts along its alignment and therefore logistics and solutions had to be developed to minimize disruptions or interferences with other contractors and the neighborhood. The paper describes this innovative approach. C305 CONTRACT APPROACH C305 contract was split into three drives, to be excavated by four EPB TBMs 7.1m diameter, as shown in Figure 1. •,Drive Y: 8.2km long between Limmo Peninsula and Farringdon Station in the city center •,Drive Z: 2.7km long between Pudding Mill Lane and Stepney Green Junction •,Drive G: 0.9km long between Limmo Peninsula and Victoria Dock Portal in the East. Crossrail C305 Project scope of works included the excavation of TBM tunnels and shafts at Limmo Peninsula and Stepney Green (including 17m span turnout caverns), along with the requirement to traverse station and shaft structures of other Crossrail contracts. Limmo Peninsula Site was a strategic element as it was the only access point on the tunnel alignment with sufficient available area at the surface for tunnelling logistics and also connected to the Lea River, tributary of the River Thames which facilitated marine operations for segment supply and muck removal. These were the reasons for operating Drive Y & Drive G TBMs from that location. Drive Z TBMs were originally planned to be launched from Stepney Green to Pudding Mill Lane, supplying the TBMs during Drive Z excavation from Limmo Peninsula site through the excavated section of Drive Y between Limmo and Stepney Green. During the early stages of the project, a value engineering proposal with a new tunneling strategy was agreed wherein the Pudding Mill Lane contractor would provide space for TBM assembly and operation in their portal, allowing for reversing Drive Z excavation and launching the two TBMs from Pudding Mill Lane. This optimization reduced some of the shaft requirements at Stepney Green which were contingent upon critical enabling works and provided program certainty and cost savings for the full Crossrail Project. It allowed for the reuse of both the Drive Z TBMs for Drive G excavation from Limmo to Victoria Dock Portal thereby saving on the procurement of two TBMs, in addition to easier logistics for both Drives Y&Z, therefore de-risking the TBM excavation process and the C305 Project program completion."

Jan 1, 2016

By A. Ang-Ug, L. Gurieff

"The Phu Kham Cu-Au mine in Laos is owned and operated by Phu Bia Mining Limited. The deposit is a complex and low grade Cu-Au porphyry ore. The rougher feed has a particle size distribution of 80% passing 110 µm, and the rougher concentrate is reground for cleaning to 80% passing 25 µm. The Cu losses in the cleaning circuit are primarily in the <12 µm fraction. A randomised paired ON-OFF test of magnetic conditioning in one of the two parallel cleaner 1 circuits was undertaken. The results showed that with magnetic conditioning there was approximately a 10% reduction in the <12 µm Cu distribution in the cleaner 1 tail to a 98% level of confidence. The Cu distribution in the <12µm fraction is a less variable measure of changes in the <12µm Cu recovery, therefore, this was used to evaluate the impact of magnetic conditioning. Subsequently, magnetic conditioning was installed in both cleaner 1 circuits and the plant results monitored after this installation. Comparing the plant results immediately before and after this installation showed that there was a 20% reduction in <12µm Cu losses to the cleaner tail. INTRODUCTION The Cu-Au, Phu Kham Mine (PKM) is located within PanAust's Phu Bia Mining Contract Area in Laos, approximately 140 kilometres from the capital city, Vientiane. PKM is PanAust's flagship operation and the significant cash flow generated by PKM has supported PanAust’s growth, while contributing to a strong balance sheet. PKM comprises an open-pit mine and a conventional milling and flotation operation that produces and exports a Cu and precious metals concentrate. The concentrate contains around 23% Cu, 6 ppm Au and up to 35 ppm silver. Process Overview The PKM deposit consists of complex heterogeneous mineralogy horizons of Cu-Au stockwork and skarn mineralisation. It contains areas of soft-leached zones, overlying transition zones and supergene chalcocite dominant secondary Cu mineralisation and clay-rich gangue. Areas of high As and Zn also pose a challenge in treating the highly variable ore. In addition, hardness of the ore increases with deposit depth. The ROM is hauled to a primary gyratory crusher to produce a coarse ore stockpile with size distribution suitable for the 13 MW semi-autogenous mill. The SAG product feeds two parallel ball mills each equipped with a cyclone cluster producing a product particle size distribution of 80% passing 110 µm. The conventional flotation circuit consists of two parallel rougher banks. The rougher concentrates feed the regrind cyclone where the underflow is split and reports to two parallel, 3MW, M10000 IsaMills. The regrind mill discharge combines with the regrind cyclone overflow with a product particle size distribution 80% passing 25 µm and reports to the Jameson cell."

Jan 1, 2018

By Rocky Gunderson

When operations begin early next year at the $100-million Port Kembla coal loading facility in New South Wales, Australia, a sophisticated computer system, directed by two of Hewlett-Packard&apos;s HP1000 mini-computers, will perform a number of functions ranging from monitoring and reporting arrivals and departures to maintaining a library of events for up to one year. The three-processor HP1000 system configuration, valued at $215,000, is one of the largest single orders, in terms of dollar value, ever submitted in Australia for Hewlett-Packard&apos;s line of engineering and manufacturing minicomputers. The processors will be linked in a fully "backed-up&apos;&apos; configuration using Hewlett-Packard&apos;s fourth generation distributed networking system, DS/1000-IV, making the system one of the most sophisticated in Australia. Interfaced to a number of weightometers and programmable logic controllers (PLCs), the computers will be the heart of a coal inventory system for the facility which, in its first phase, will be capable of handling more than 13.5 Mt/a of coal. The computers will report on all plant functions, including conveyor belt and water spray operations. Specifically, the system will: • Monitor and report all coal movements related to road and rail deliveries, dispatches from ship loaders, and interstockpile transfers. •Maintain a &apos;&apos;running log" of all events pertaining to overall plant operations, such as conveyor starts and stops and anti-pollution spray activation. • Accept and maintain plant data entered manually or acquired automatically from various remote locations via either visual display units (VDUs) or PLCs. • Maintain complete historical records of all transactions and related plant events for up to one year. • Provide a facility for stockpile management, modeling-type programs, and training or other simulation activity. The facility was designed with the following characteristics in mind, based on an analysis of requirements for an automated coal loading operation that would optimize productivity and be flexible to change and grow with facility needs and changing technology: • Continuous Operations-Due to the need for continuous plant logging and control, the overall facility will be capable of uninterrupted, 24¬hour operation. • Handling Current and Projected Workloads-The facility will be capable of not only handling current workloads, but also any additional workloads required during future coal loading operations. • Expansion-The facility will be capable of expansion, for a minimum cost, at any time with minimum disruption in operations. • Single Source of Supply and Maintenance-The facility will be supplied and maintained by one supplier, through hardware and software maintenance support contracts. System Configuration Two HP1000 minicomputers, each with 500K bytes of main memory, will be front-ended by a pre-processor with 256K bytes of main memory. These three systems, active, backup, and front-end, will be interconnected into a triangular array, as shown in the accompanying diagram. Under normal conditions, the front-end will transmit plant status data to one of the main systems, whose primary function will be to monitor coal flow and maintain a relevant dialogue with operators. The front-end, therefore, handles all communication with the plant PLCs, effectively removing this overhead from the current plant monitor (either of the two main systems). The front-end pre-processes and post-processes all information flowing from the plant monitor to the PLCs and vice versa, thus effectively handling all communication between the two units. A second main system will handle reporting, administrative, and modeling functions, and will also be capable of performing both front-end and monitoring operations. Linking all

Jan 11, 1981

By C. E. McFarland, N. W. Kirshenbaum

Cortez Gold Mines is located about 75 miles southwest of Elko, NV. Activity in the mining district dates from 1862. The current operation developed from a 1963 joint venture of Webb Resources, The Bunker Hill Company, Vernon F. Taylor, Jr., and American Exploration & Mining Co. Three years later, the USGS discovered gold on the property following a regional geochemical survey. Drilling in 1966 and 1967 identified 3.4 million st of oxide ore grading 0.28 oz Au/st, and a 1700 st/day countercurrent decantation mill was commissioned in 1969. Heap leaching started in 1971 on low grade ore and continues to the present. The mill was shut down in 1976 following exhaustion of known oxide reserves. Mobile equipment was sold and the proceeds committed to local exploration. In 1980, a new plan of operations was developed starting with existing low grade and newly discovered mill ore. The mill resumed operations in 1981 and has been operating to date. A series of metallurgical innovations, culminating in the commissioning of a new fluid bed roaster in the summer of 1990, has enabled treatment of a series of increasingly refractory ores. Current partners in the venture are Kennecott Corporation, Vernon F. Taylor, Jr., and Placer Dome U.S. Inc., manager of the operation. Idaho Mining Corp. holds a 7.5% carried interest.

Jan 1, 1992

By C. P. Lazzara, F. J. Perzak, C. C. Hwang, C. D. Litton

Fire development and spread along conveyor belts in ventilated ducts were investigated experimentally and theoretically. Various types of conveyor belts used in mining applications were ignited and burned in a full-scale gallery under various flow conditions. The flame spread rates depended strongly on the ventilation air speed. The time-temperature traces of gas and belt obtained at 12 feet from the entrance show that a rapid belt surface temperature change takes place prior to a change in the gas temperature, indicating that radiative heat transfer from the flame to the belt surface plays an important role. Further, anomalies in the flame spread rate in the vicinity of 1.5 m/s air speed (i.e., much greater rate than that observed at either higher or lower speeds) can be explained through the mechanism of flame tilt and the resultant view factor between the flame surface and the belt surface. In order to correlate the fire spread with material properties of the conveyor belts (such as the specific heat, the thermal conductivity, and the pyrolysis temperature) and the fire environment (such as the gas temperature and the ventilation air speed), a theoretical model has been developed. This model is based on the experimental observation that the radiative heat transfer is the dominant mode of energy transfer ahead of the flame front. Agreement between the theory and the experimental results is good.

Jan 1, 1991

By K. Anim, C. Calderon-Arteaga

Located in Mojave, CA, The Soledad Mountain mine is an Open pit Heap-Leach gold Mine, which is operated by Golden Queen Mining Company LLC. under private capital. Open pit mining began in 2015 while full production was reached in 2016. The open pit mine feed a processing plant that can process more than 13K tons per day of ore which is sent to a heap leach pad. The Soledad Mountain project is a poly metallic deposit with Au and AG being recovered as payable metals. As the mine became bigger after moving to the east pit phases, Golden Queen was facing new challenges to control the production and accurately determine KPIs to improve/increase the production. To maximize returns and asset value, a new fleet management system (FMS) was adopted and implemented. The new FMS has enabled the mine to interconnect the different stages of the mining, as well as to recognize issues and implement the necessary corrections. With the associated increase in complexity in the process, the requirement of the ore control system to accurately predict ore feed characteristics is critical to maximizing metal recovery. Implementation of new daily and weekly plans were needed to ensure the ore delivery and meeting the tonnage goals, while allowed the equipment operators to better geolocate and to maximize the equipment production. These conditions alongside with Golden Queen’s drive to increase profitability and maximize net asset value has created challenges. These challenges are numerous and multifaceted. However, the ability to accurately route the material from the mine, is critical to site success and some of these challenges have been overcome by the adoption of the new FMS, the implementation of daily and weekly plans and upgrades in the ore control workflow. Examples of how the integration of the new systems allowed golden Queen to improve production strategy, are discussed in this article.

Mar 2, 2022

By Rory P. A. Ball, Mark Briggs, Martin Dix

"Tunnel professionals should inform project stakeholders on the reality that tunnel projects are not 100 percent devoid of the need for excavations or public inconveniences during both design and construction phases. Competing stakeholder objectives to limit these disruptions must be weighed against the need to mitigate risks and to produce a constructible, operable and maintainable end product. Perhaps the approach we should take with stakeholders, also known as Authorities Having Jurisdiction (AHJs), is sharing memorable case studies that bring to life the potential risks so often buried within lengthy risk registers. This paper provides a sobering case study describing what can occur if the presence and/or location of utilities and other obstructions are not fully understood due to restrictions placed on exploration or mining operations. In this instance, the Microtunnel Tunnel Boring Machine (MTBM) encountered a buried concrete structure, followed by rows of abandoned wood piles, before finally colliding with an active high-pressure gas main under a bustling coastal highway. Multiple stakeholders imposed tight logistical and other work restrictions, compounding the difficulties experienced during the drive. However, the difficulties were effectively managed through the project team’s proactive collaboration and communication with everyone involved. INTRODUCTION Some of the most important decisions that influence the ultimate success or failure of a project may not be made by design engineers. Instead, these decisions are often made by project stakeholders and third-party agencies. Tasked with protecting the best interests of their users, these agencies are cautious of potential impacts associated with project construction and subsequent use. Unfortunately, actions required (or restricted) by stakeholders often result in unwanted ripple effects that negatively affect the very users they are trying to protect. For example, a mandate limiting a shaft site to an unreasonable size may be intended to reduce local business impacts, but may actually increase impacts as more supply and truck hauling is required."

Jan 1, 2016

By L. Rudolphy, P. Tähkiö

"The cPlant is a modular flotation plant which has been designed to minimize capital expenditure and risk. The plant is based on a number of standard modules, for both flotation and ancillary equipment, which can be configured to give the required flowsheet for the ore being treated. All of these modules can be rapidly deployed and erected onsite, minimizing not only engineering time and site preparation but reducing the time taken to get the plant up and generating revenue. Given the paradigm shift in flotation circuit design that has been employed in the cPlant it may allow smaller, previously uneconomic deposits to be exploited and create a more cost efficient upgrade route for existing plants. This paper introduces the cPlant and presents a case study comparing EPC cost and development timing of a cPlant against a traditional flotation circuit design. INTRODUCTION In the development of any mining project the cost associated with process plant engineering, equipment procurement and installation can affect the financial viability of a project. This is of special significance for smaller scale mining projects which perhaps don’t have the mine-life or revenue generation to justify the payback on a modern processing facility. Listening to customer feedback and understanding the challenges that small to mid-sized projects can face lead Outotec to the development of the cPlant. Modularization of mineral processing plants isn’t a new idea with a number of examples being reported in literature for gravity gold (Cabot, Trudel and Cabot, 2001; Gray et al., 2006), dense medium separation (September and Abate, 2006) and even hydrometallurgy (Saario et al., 2013). All these plants have been developed to try to improve on the traditional economics associated with fixed processing plants. Using standardized modules to construct a plant reduces engineering time and design costs which can both be beneficial to the outcome of a project. In addition the modular nature of the plant lends itself to transport to remote sites and rapid installation with only minimal site preparation required. A plant of modular design also has several other advantages over its conventional cousins. Firstly it is relatively easy to expand by duplicating existing modules. Secondly the modules can be treated as building blocks for the process and rearranged if a change in conditions requires flowsheet adjustment. Thirdly, there is potential to disassemble and remove the modular units at the end of the mine life. The ability to easily disassemble, re-pack and transport the plant to a new location not only is important to the long term environmental footprint of an operation but can also be seen as a bonus to an operator that has a number of small ore deposits. If applied in this way modular plants have the potential to create a whole new operating model for previously unviable ore deposits."

Jan 1, 2016

By R. J. Sweigard

One of the foremost problems in reclaiming prime farmland is compaction of the subsoil which is caused by the reclamation equipment. Wheel tractor-scrapers are most commonly used to replace subsoil and have been blamed for the majority of the compaction problems. Two methods of alleviating this problem that are presently being considered are mechanical subsoil loosening machines and truck- shovel combinations for subsoil handling. A field study was conducted in which dry bulk density measurements were taken in an effort to determine the effectiveness of truck-shovel combinations and subsoil loosening equipment in reducing bulk density in comparison to typical scraper replacement.

Jan 1, 1987

By William P. Walsh

In December 1983 the author undertook an investigation in east Texas which was organized to learn the feasibility of applying geophysical techniques over shallow lignite deposits. The work embraced experimental high resolution seismic reflection and offset Wenner resisitivity sounds over three 4 to 4 mile test sections. This site also was sponsored by Woodward-Clyde Consultants (WCC) and a consortium headed by North American Coal Corporation. The principal objective of this investigation was to learn whether the aforementioned geophysical techniques could be applied over shallow lignite deposits (i.e. located at approximately 100&apos; to 300&apos; in depth) and consequently provide structural and stratigraphic information useful for resource and reserve characterization. A secondary objective was to determine if these same techniques could disclose the nature of the overburden and the distribution of ground water therein.

Jan 1, 1985

By L. E. Bowman

Efficient filtration of fine kaolin particles plays a crucial role in processing of raw kaolin to a marketable product. Oftentimes, filtration Is the rate controlling step of the whole process. As a consequence, plant production is dependent, to a great extent, on the rates being achieved In filtration. In order to alleviate the bottleneck in production, Nalco Chemical Company initiated a reagent development program to chemically enhance the performance of the filtration units. Filler aids of different classes were synthesized for evaluation. These include reagents whose primary mode of functionality were: coagulation, flocculation, thickening, and combinations of the preceding. All reagents that were synthesized and tested were listed under the appropriate Food and Drug Administration sections of the Code of Federal Regulations. This paper discusses the development and application of a new reagent that Improves the filter production rate with minimal Impact on filter solids. The results of laboratory filter studies along with plant data are presented and discussed. Plant data indicate that this reagent is capable of increasing production rates by as much as 35% on various clays of coarse particles to the finest fractions, as well as clays that are calcined. The reagent&apos;s Impact on solids content, re-slurrying characteristics, Brookfield and Hercules viscosity, and drying is within the standards set by plants who have evaluated and now use this product.

Jan 1, 1993