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By Paloma Lazaro, Moe Momayez

Heat-related illnesses (HRI) are relatively common in both hot surface and underground mining operations. When workers are exposed to extreme heat or strenuous work in a hot environment, they become prone to heat stress. Heat strain is the result of the body’s response to external and internal heat stress. It is therefore vital for the conditions leading to heat strain be detected and treated in a timely manner. Heat-related illnesses are manifested by exhaustion and heat stroke. The predicted heat strain (PHS) [ISO 7933 (2004)] model has been developed to predict the health condition of the worker in terms of core body temperature and water loss. The PHS model tested in this study is based on eight physical parameters that are measured at different intervals during a work shift. They include air temperature, humidity, radiation, air velocity, metabolic rate, clothing insulation, posture, and acclimatization. The model predictions are then compared with a direct physiological measurement, such as core body temperature. We present the results of an extensive study that monitored and predicted body’s response to heat stress under different environmental and working conditions. The PHS model provided reliable results in most instances in comparison with other prediction methods currently in use in the field.

By Paul R. Smith

The Colorado School of Mines Research Institute (CSMRI) was founded in 1949 to fill mining industry and government needs for minerals research and development. The operations of scores of mines, mills, and plants around the world are based on the results of work done by the Research Institute. Among other things, the Research Institute conducts studies in geology, mine planning, mineralogy, size reduction, minerals processing, and hydrometallurgical techniques in extractive metallurgy. Many CSMRI projects also involve energy and environmental considerations. What follows is a summary of some of the studies in which the Research Institute has been and is currently involved, as well as some comments on trends and developments in the industry.

Jan 2, 1982

By PETER ROBINSON, KEVIN BARBER, OLIVER WHATNALL

The investigation and uptake of filtered tailings continues to grow around the world, but cost and scalability are deterrents for mining companies. Filtration technology that is currently in use is unable to meet the needs of many operations and projects that would otherwise adopt filtered tailings. For tailings to reach the desired moisture content for dry stacking, the majority of processes require pressure filtration, with significant upfront and ongoing maintenance costs. Given the comparative lower costs associated with low-pressure Viper vacuum belt filtration, this technology has the potential to alleviate dependency on high-pressure applications and make efficient dewatering and handling of tailings a more economic and sustainable solution.

By W. H. Dickinson

The performance of seven antiscalants spanning a range of chemistries was evaluated for control of calcium carbonate (CaCO3) formation in gold processing applications. Three preferred chemistries were identified which provided up to 100 percent inhibition in static jar tests when applied at 30 ppm dosage. The three products were further evaluated using a model carbon extraction circuit developed for this application. The test circuit enabled direct measurement of calcium carbonate formed on the carbon from a supersaturated solution under dynamic conditions. The antiscalants lowered CaCO3 buildup on the columns by 15 - 26 percent compared to untreated controls. Impact of the antiscalants on the rate and extent of gold loading onto a carbon adsorbent was evaluated in laboratory carbon-in-pulp (CIP) studies. The antiscalants generated a 25 - 35% increase in gold loading at gold extraction efficiencies up to 65%. On-site testing at a gold processing facility demonstrated that 10 ppm of the preferred antiscalant was able to fully suppressCaCO3formation in thickener overflow water.

Feb 27, 2013

By Douglas W. Fuerstenau, Pradip Pradip

The design and development of selective flotation collectors has been the key to the remarkable success of flotation in beneficiating complex, difficult-to-process ores. Sustained research efforts in the field over the past hundred years have led to delineating the scientific basis of selective mineral flotation in terms of the crystal chemistry and the surface and colloid chemistry of minerals including their solubility, and the aqueous solution chemistry of added reagents. It is now well-established that the electrical double layer theory (EDL) is the most powerful means of quantifying the relative strength of mineral-reagent interactions in the case of nonsulfide minerals. We illustrate the utility and the power of the EDL in delineating the science underlying selective mineral flotation with the help of a few examples taken from our own work, in particular on the selective flotation of rare-earth minerals (bastnaesite) from associated semisoluble minerals (barite and calcite) using alkyl hydroxamate collectors and the flotation separation of lithium-containing minerals (spodumene) from associated alumino-silicate minerals with oleate (fatty acids). Both of these mineral separation systems are of contemporary research interest and of immense value to the industry today. Recent advances in utilizing molecular modeling computations, particularly in the context of quantifying the effect of crystal chemistry and the relative distribution of adsorption sites available on mineral cleavage planes, are also reviewed.

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By P. Hickey, J. Spenceley, T. J. DeMull

Development of the Batu Hijau Project was successfully completed in the fourth quarter of 1999 with the final handover and start-up of ore processing facilities. The development project had started more than three years earlier, in August 1996, when the Owner, PT. Newmont Nusa Tenggara (PTNNT), awarded an EPC contract to Fluor Daniel (FD) for design and construction of the project including: copper concentrator, port, power plant, town site, and infrastructure. PTNNT managed the development of the mine and procurement of mine equipment with its own forces. Bringing the Batu Hijau copper deposit into production was the largest mining project ever undertaken. Development of Batu Hijau was a complex project involving the work of tens of thousands of people in all parts of the world to complete engineering, manufacture and deliver equipment, supply materials, and build the plant. The ore deposit is located on the tropical island of Sumbawa in a remote and undeveloped section of Indonesia. The location and environment presented challenges for all phases and aspects of the project. To meet the challenges, the project team combined good planning and teamwork to best utilize the resources available. This approach assured continuity of personnel through construction to operations and minimized cost, resulting in completion of the project ahead of schedule and under budget.

Jan 1, 2001

By R. E. Moore

Refractories are unique ceramic materials, which are used in large quantities in steel making furnaces, metal smelting vessels, and glass melting tanks. They are required to possess high thermal shock properties and good slag corrosion resistance as well as creep resistance at high temperatures. Therefore, they are made from very refractory minerals such as lime, periclase, corundum, spinel, and zirconia. Slags are vitreous materials produced as a residue in steel refining processes. They cover a wide range of compositions and may contain pure oxides, silicates, and sulfides as well as fluoride phases depending on the melting and smelting processes. These minerals exhibit spectacular cathodoluminescence color under electron bombardment; therefore, cathodoluminescence (CL) microscopy is found to be a superior technique for the characterization of refractory corrosion by slags. Examples included in this study are (1) reaction of fluorine containing mold slags with ZrO2-C nozzle refractories promoting crystallization of the Cuspidine, Ca4Si2O7(F,OH)2, (2) corrosion of fusion cast refractories in TV panel glassmaking furnaces and formation of glass defects, and (3) reaction of spinel based castable refractories with copper smelting slags.

Jan 1, 2001

By Ludger Suarez-Burgoa

At the Porce III Underground Powerhouse Complex in Colombia, the observational method (Peck, 1969), was used to provide information to an underground wedge and a 2D Finite Element Method numerical models, both used to estimate the mechanical behavior of the hoisting rock mass. The observation process consisted in collecting fault events in the field and in interpreting Multiple Point Borehole Extensometers and Surface Convergence Displacement Points readings. The calibrated models were employed to predict the behavior of the pillars formed between the machine and transformer caverns. The observational method is an important activity during excavation of large openings and provides arguments to understand the rock mass mechanical behavior.

Jan 1, 2008

The 23rd annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held at the Tucson Marriott University Park Hotel, Tucson, AZ on Saturday, Dec. 3, 2005. The Mining Foundation of the Southwest is a non-profit organization. It educates the public about the mineral industries and reports outstanding accomplishments in the fields of mining and the earth sciences. This year’s inductee, guest of honor and featured speaker at the banquet will be Pierre Lassonde, president of Newmont Mining and resident of the World Gold Council. He is one of Canada’s leading gold analysts.

Jan 1, 2005

By Dominick Mandalari, David Mast, Heather Ullinger, Juan Granja, Amanda Foote

The City of Akron will construct the Northside Interceptor Tunnel project, a U.S. EPA/ DOJ CSO Long Term Control Plan Project. The system will provide at least 10.3 million gallons of storage in a 16.5-foot finished ID and 6,660-foot-long rock tunnel. The system will reduce both overflow volume and number of overflow structures on the Cuyahoga River. The project includes deep drop shafts and more than 3,000 linear feet of 48 to 96-inch I.D. sewers installed by trenchless construction methods. This paper will discuss the project background, ground conditions, and other challenges overcome during the design phases.

Jun 13, 2023

By Robert M. Semple, Harvey W. Parker

INTRODUCTION Two promising innovative tunnel support systems are being developed by the Civil Engineering Department of the University of Illinois. One of these is a lining which can be placed by a slipform located immediately behind and contiguous with a tunneling machine. Recent advancements in construction materials appear to provide the breakthrough required to make such a system feasible and practical. The lining material which permits this construction scheme is wire fiber reinforced concrete made with high, very early strength regulated-set cement. Parts I and II of this paper relate to this slipformed liner. Part I discusses the material and equipment required to install the liner. The "Extruded Liner System" (ELS) has been devised to place the lining. This ELS concept is briefly described and a tentative development program is outlined. In Part II, the physical properties and practical construction aspects of the liner material are discussed and a program for structural testing of 10-ft diameter prototype tunnel supports is presented. Part III contains descriptions of improvements to conventional steel-rib tunnel supports. It is shown that square tubular box sections are structurally superior to wide flange sections for complex loading conditions often encountered in rock tunnels. Analytical studies and tests on connections have been performed to evaluate their structural behavior. These are presented along with a program for comparative large-scale tests on horseshoe-shaped frames with a 10-foot span. This research is being conducted by the Department of Civil

Jan 1, 1997

By J. Geisler

When addressing Germany’s resource supplies, we need to distinguish between those domestically available and imported ones. Resource extraction ostensibly competes with the designation of protection areas. However, the parallel existence of wildlife and plant life, and operations in the areas used for resource extractions is continually underestimated. The European Commission has compiled guidance documents facilitating the extraction of resources from protected areas. With regard to resource productivity, the market appears to be the appropriate instrument for minimising resource consumption. Policy makers are now called upon to create a legal framework leading to a consensus accepted by society.

Jan 1, 2011

By Charles Merguerian

In medium- to high-grade metamorphic terrains such as found in New York City(NYC), rock mass texture and mineralogy are important factors in predicting TBM penetration destiny. Integration of data from over two decades of traditional field and tunnel mapping suggest that hard-rock TBM penetration in the NYC area depends upon textural, mineralogic, and structural control. The bedrock of NYC consists of many different lithologic units of varying age, composition, texture, and metamorphic grade including many varieties of intrusive rock. In addition, brittle faults of numerous orientations cut the polydeformed crystalline bedrock, producing zones of highly fractured and disturbed ground and high water inflows. Pre-bid compilation of published bedrock data, drill core analysis by geologists to establish lithologic and mineralogic trends, integrated surface geologic mapping along a proposed alignment, and targeted petrographic and geotechnical investigations to characterize the rock mass conditions together constitute an important prelude to successful subsurface bidding and tunneling. A carefully planned program of as-built geological mapping, structural analysis, fracture class mapping, and monitoring of machine performance data provide important information for adjusting to changed conditions. In complex terrains, a clear understanding of the structural geology of any proposed tunnel line is the simplest and most cost-effective method to mitigate losses encountered during TBM tunneling.

Jan 1, 2005

By James Corcoran, Richard McLane, Joseph DeMello, Eric Carlson, Hans van de Vrugt

The Los Angeles County Transportation Authority’s Purple Line Extension Phase 1 is a $3.12 billion (USD) design-build, underground heavy rail project, connecting an existing station at Wilshire Boulevard and Western Avenue and extending west 3.92 miles under Wilshire Boulevard and terminating approximately 550 feet west of Wilshire/La Cienega Station. The project alignment runs through the heart of the world famous La Brea Tar Pits and one of the world’s largest urban oil elds. This paper presents a case history of the planning, design, and construction efforts to achieve successful construction of the bored tunnels through Reach 3 of the alignment. Further, this paper outlines the proactive partnership between the owner, Los Angeles County Metro (Metro), the Design Builder, Skanska-Traylor-Shea oint enture (STS), and Southwest Geophysics who provided the geophysical services. Specically, the project included background review of historic site data (e.g., oil eld maps, building foundation plans, historic aerial photographs, etc.), geophysical demonstration testing to ascertain the capability of borehole magnetics to detect oil wells, directional drilling of thousands of feet of horizontal and vertical boreholes, collection of high resolution magnetic gradiometer data along vertically and horizontally cased boreholes as well as the collection of surface magnetometer data, discovery (“ground truthing”) of detected geophysical anomalies, and abatement of potential obstructions within the tunnel alignment.

Jun 23, 2024

By Kevin Beirne

Most people involved in the mining industry are familiar with student-industry co-op work-study programs. Many colleges and universities have used them for years. Northern College’s Haileybury School of Mines student co-op program adds a new dimension of productivity to the college and the mining industry. The college is located in Hailey-bury, Ontario, Canada. An example of the program’s success is the school’s relationship with Sabin Metal’s SMC (Canada) Ltd.’s McAlpine Mill in Cobalt, Ontario. Students gain practical knowledge and experience while industry gains an eager-to-learn worker. And many of the college’s advanced research services are made available to industry to supplement their own capabilities. The McAlpine Mill was established to provide custom milling of slags and ores. It also recovers metal values from other products of the primary and secondary precious metal industries.

Jan 1, 1999

By Jim Owens

The methodology of quarrying changed significantly in the Indiana limestone industry in the 60 years between Sept. 11, 1941 and Sept. 11, 2001. The former was the date of the Pentagon groundbreaking ceremony, while the latter was when the building was damaged by American Airlines Flight 77. So too, though to a lesser degree, did the machinery and methods used to fabricate the stone. The rededication ceremony on Sept. 11, 2002 marked the end of the Phoenix Project, as the rebuilding effort was named. The story of this remarkable project illustrates what the American construction(and Indiana limestone) industry can accomplish when working toward a common goal.

Jan 1, 2005

By AMAN SONI, JONATHAN G. BAGGETT, Nino Ripepi, JUAN J. MONSALVE, Richard Bishop

Underground stone mines are vulnerable to karst void formations due to the erosion of carbonate rocks by groundwater flow. The voids or cavities may lead to hazards including ground collapse and sudden outflow of clay-rock sediments during the development of the mine. This study evaluates the effect of karst voids on the strength of pillars in an underground room-and-pillar limestone mine. Ground-penetrating radar (GPR) surveys were interpreted to map the void boundaries inside a karst-affected pillar. A combination of LiDAR scanning and virtual discontinuity mapping is used to formulate the discrete fracture network (DFN). Discrete element modeling (DEM) helps simulate the effect of karsts and discontinuities in the pillar models with varying stress. It is observed that the cavities may lead to a significant reduction in pillar strength. Apart from posing a hazard to miners and machinery, any advance into these cavities may disrupt mine operations. This research serves as an initial step toward understanding the importance of pillar design in underground stone mines affected by karst voids to prevent local instability or pillar failures.

Sep 1, 2022

By Carlo Sampaio, Moacir Veras, Aaron Young, Carlo Petter

"Three major challenges for the mining industry are the minimization of energy use, water consumption and environmental impact. Therefore, any technique that reduces milling waste, decreases water usage and shrinks impact during mine life must be considered a major innovation in mining.To these ends, one of the most impactful developments in mining within the last 10 years has been the expanded use of high technology sensors to create preconcentrations of mine ore (Jönsson, 2014). The most common sensors used are charge-coupled device (CCD) cameras, that allow through a red, green and blue (RGB) coloring system, the separation of minerals with different colors, tones and, in many cases, with differences in brightness.More recently, the development and use of dual energy X-ray transmission (DE-XRT) to enable the separation by atomic density of the constituent minerals within a given rock has become a reality. Within this work, a rapid bibliographical review of the CCD and DE-XRT methods and examples of their usage within mining and the industrial minerals sector are presented.Sensor-based sorting in miningAutomation within mining is one of the industry’s current goals. Sensors of various kinds have been used as steps toward automation in recent years, from improving the safety and productivity of haul trucks through the use of cameras and global positioning satellites (GPS), to the divination of slope failures. Just as with other mining areas, sorting has improved dramatically and made great steps toward automation in recent years (Wotruba et al., 2014).Sensor-based sorting (SBS) uses spectromatic sensors to identify intrinsic characteristics of particles and separates them by either mechanical or pneumatic means into different product streams (Wotruba et al., 2014). SBS can be used with great effectiveness to improve gravimetric beneficiation through the selective separation or preconcentration of run of mine ores (ROM)."

Jan 1, 2015

When it comes to safety in the mining and extractive industries, success is literally a matter of life and death. Anything short of perfection is not acceptable. In recent years, the mining industry in the United States has made tremendous strides in terms of health and safety for its workers. Part of that success has come with an increased focus on the issues of safety, an intense examination of procedures, liberal sharing of best practices and a focus on the synergy between safety, reliability and environment. During his closing keynote address of the Safety Management & System Reliability Conference in Minneapolis, MN on Nov. 15, Joe Driscoll, vice president of Great Basin Gold, showed a calendar from the coal fields in Pennsylvania from the early 1900s. The calendar marked the number of mine-related deaths each month. Some months, the number was as high as 50. It was an illustration of how far things have come, but there is still much more work to be done.

Jan 1, 2013