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By Peter Dietrich, Joseph DeMello, Norbert Fuegenschuh, Kerwin Hirro, Jeff Brandt, Mike Cole

This paper presents a successful case history of the ground improvement efforts and excavation of twenty-three cross passages between twin bore tunnels driven by EPB tunneling machines in Los Angeles, California on Section 1 of the Westside Subway Extension. Unique and complicated ground conditions local to the tunnel alignment include San Pedro sands, siltstone/claystone Fernando Formation, and zones of “asphalt impacted soils.” To provide water cut-off and soil stabilization, jet grouting was performed prior to TBM excavation at the location of many of the cross passages. However, upon investigating the cross passages prior to excavation, the subsurface conditions required additional measures and SEM tools to ensure successful completion of the project.

Jun 13, 2023

By M. Botz

Anatolia Minerals Development Limited (AMDL) is constructing the Çöpler Gold Project in eastern Turkey and commenced mining in the fourth quarter of 2009 with gold production scheduled to begin in the fourth quarter of 2010. The project is a 15,500 tonnes/day oxide heap leach with three-stage crushing, agglomeration, carbon adsorption and electrowinning for final metal recovery. Leach solution copper levels are expected to be relatively low during the first two years of production but will increase in later years due to higher copper content in the mined and processed ore. Over the mine life approximately 40 million tones of ore will be placed on the leach pad, which will contain about 35,000 tonnes of copper. Metallurgical testing indicates copper extraction will vary by ore type and, if controls are not implemented, may lead to copper levels exceeding 1,000 mg/L in pregnant solution. High copper levels in leach solution have the deleterious effect of increasing cyanide consumption and potentially overwhelming the ability of the carbon circuit to effectively adsorb the principal economic metals, which in this case are gold and silver. Using data obtained from laboratory leach column testwork, the heap leach facility was modeled using METSIM process simulation software to estimate the build-up of copper in leach solution over the mine life. Laboratory testwork was also performed to evaluate process conditions for treating a portion of pregnant leach solution via sulfide addition to precipitate saleable copper as copper sulfide (Cu2S).

Jan 1, 2011

By J. Chai

In order to find the behavior of dewatered unconsolidated strata during the process of injecting water through a borehole, a new type of fiber Bragg grating (FBG) sensing system was successfully used for the real-time strain monitoring of unconsolidated strata during a water injection process for a dewatered unconsolidated strata of a coal mine. The unconsolidated strata water injection test was implemented through a borehole at a depth of +115.83 to +135.15m. The employed FBG strain monitoring system and ground water level observation system were installed at the depth in the unconsolidated strata where the water injection was conducted through two different boreholes. The water injection pressures in the test were 0.1, 0.2, 0.3MPa respectively, and the total water injection volume was 4226.84m3. The relationships between the water injection pressures, water injection volume and the strain change of the unconsolidated strata, the stress and strain conditions of the unconsolidated strata before and after water injection, were analyzed. This paper presents the results of these tests, and shows that the dewatering compression of the unconsolidated strata is reduced with increasing water injection pressures and water injection volumes. Comparing the stress-strain conditions before and after water injection, it is found that the stress of the water injection strata is in tension, which confirms the theory that the settlement of the thick unconsolidated strata is directly caused by the reduction of ground water levels. The high sensitivity and stability of the FBG monitoring system used was able to realize the real-time strain monitoring of the water injection process within a deep unconsolidated strata. This FBG monitoring system and the test results presented are very important for understanding further treatment of settlement in unconsolidated strata.

Jan 1, 2012

By Paul C. Schmall, John F. Donohoe, Arthur B. Corwin, Derek Maishman

Ground freezing was utilized to provide complete stability of the excavation face and complete groundwater cut-off for the jacking of the three tunnel boxes for the Interstate 90 / Interstate 93 approach to the Fort Point Channel crossing. Through a wide range of geological conditions and large buried obstructions, the freezing provided complete stability of the face so that a 11.5 m (38 ft) high free standing vertical face could be mined without the need for any additional face support. Obstructions were incorporated into the massive frozen ground matrix, and held in place so that they could be excavated with a minimum of disturbance. The freezing provided an absolute groundwater cut-off, and permitted the work to be done without disturbance to the active rail system immediately above. With the use of instrumentation such as borehole thermocouples, the effectiveness of the freezing was guaranteed and the jacking proceeded with complete confidence and assurance of the ground conditions ahead.

Jan 1, 2001

By Steve Kral

For the past several years, copper producers have faced a tough business climate. Nagging low prices forced many them to reduce their production and make other drastic cutbacks just to breakeven. And sometimes even that did not work. But, like other downturns in the industry, this latest dismal copper market allowed technology to make further inroads into mining and processing operations. Now that the copper market appears to be making a turn for the better, those years spent investing in technology by equipment manufacturers and forward-thinking mining companies should begin paying off.

Jan 1, 2004

By John Davis Morgan

The uncertain world conditions of the present time require that the United States be prepared to meet: a. all-out nuclear war with attack on the United States b. limited wars (anything smaller than (a.) c. political, economic, and/or psychological warfare. Our present position as a major world power derives in large measure from our free institutions and our great industrial productivity, and our productivity in turn depends on an ever-continuing flow of raw materials from the earth - metals, minerals, fuels, and agricultural products. The United States, with only about 6% of the world's population, uses from one-third to two-thirds of the world's annual supplies of 'most metals and minerals. The United States strategic materials stockpiling program is designed to enhance our national security posture: as stated in the preamble of the Stock Piling Act, to decrease and prevent wherever possible a dangerous and costly dependence of the United States upon foreign nations for supplies of strategic and critical materials in times of national emergency. In times past, the Good Lord himself has ordered some stockpiling. The Book of Genesis in the Bible tells how Pharaoh of Egypt was directed to set aside one-fifth of the produce of the land in each of the seven good years to meet the needs of the seven bad years that were to follow: this would be a stockpile of about two years? normal use. Our cultural heritage often reminds us of the wisdom of stockpiling, as in the case of the stories about the provident squirrels that gather their nuts in an orderly manner in the f all to prepare for the winter's cold. And the old proverb about a bird in the hand being worth two in the bush points out clearly the value of something that is directly at hand.

Jan 1, 1960

By Evan J. Owen, Virginia T. McLemore

Rare earth elements (REE) and critical minerals are increasingly becoming more important in our technological society and are used in many of our electronic devices (such as cell phones, computer monitors, wind turbines, etc.), batteries, and magnets. Measuring REE and critical minerals in ashed coal approximates the REE and critical minerals in the fly or bottom ash remaining after coal is burned at a power plant, where REE and other critical minerals could be leached. In New Mexico, there are 26 coal fields in Late Cretaceous rocks in the San Juan and Raton Basins. These rocks are being characterized as part of the DOE’s CORE-CM (Carbon Ore, Rare Earth, and Critical Minerals) program. Higher concentrations of REE (as much as 2103 ppm total REE) are found locally in ashed coals from the basins. More chemical and mineralogical analyses are required to fully understand the distribution and origin of REE in these deposits. As the demand for REE increases because of increased need and short supplies, the dollar value per ton of ore rises, enhancing deposit economics, perhaps even from coal.

Feb 1, 2025

By S. Boone, J. N. Shirlaw

INTRODUCTION Soft, near normally consolidated clays generally provide ideal conditions for tunneling using Earth Pressure Balance (EPB) shields. It is easy to turn the clay into a low permeability, viscous spoil that can be pressurized to maintain the required face pres-sure. Despite this, there are records of relatively large, and often quite variable, surface settlements over EPB driven tunnels in soft clay. To understand this variation it is necessary to identify the various factors that contribute to settlement. Tunnels in soft clay are ideal for study these effects in the field, as an unsupported void will close almost immediately, due to the low shear strength of the soil. In the short term, deformation in a soft clay will occur at constant volume, so short term surface settlements can be related to movements at tunnel level. In this paper, data will be used from EPB driven tunnels in Singapore marine clay. In all of the cases discussed the lining consisted of precast concreted segmental rings erected in the tail of the shield. The marine clay in Singapore has been studied, among others, by Tanaka et al.(2001). The clay typically has a plasticity index of 40 to 60, and the undrained shear strength (SU ) can be derived from: SU = 0.22 svo' where svo' is the current vertical effective stress. Figure 1 shows a summary of undrained strength/depth plots used for design on two sections of Singapore’s North East Line. The stability of a tunnel in clay can be assessed by comparing the stability number (N) of the tunnel with the stability number at total collapse (NTC). The stability number can be calculated from the equation: N = (?Z + q – Pt)/SU where: ? = the average unit weight of the ground above the springline of the tunnel Z = the depth to the springline of the tunnel from the ground surface q = the surcharge Pt = the support pressure within the tunnel The stability number at total collapse depends on the size, geometry and depth of the tunnel, and typically ranges between 5 and 9. Charts for assessing the number at total collapse are provided in Kimura and Mair (1981), based on the testing of model tunnels in a geotechnical centrifuge. For tunnels in the Singapore marine clay, the stability number of an unsupported tunnel would be over nine if the tunnel ois more than 8m deep. As a result, a support pressure

Jan 1, 2007

By M. Adnan Göksel

Pyrite cinder is generated by roasting pyrite for sulfur dioxide production. It contains up to 62% iron, but also may contain other hazardous or toxic materials such as Zn, Pb, As, T1, Cd, Cu, Sn and S. Furthermore, the physical characteristics are not properly suited for conventional sintering. As a result pyrite cinder is considered to be unsuitable for iron and steelmaking or for outside storage because of its potential for causing environmental problems. In recent years industrialized nations have put increasing pressure on the manufacturers to either use such waste products or properly dispose of them. In this study, solutions to both the iron recovery and disposal problem were attempted by pelletizing the pyrite fines with internal carbon. The pellets, after hydrothermal hardening, were reduced and melted in a furnace for hot metal production. Hot metal of usuable quality was produced and the hazardous materials were either collected with the fumes or in the slag.

Jan 1, 1984

By Huiqin Yao, Dongmei Liu

The study investigated the potential use of low activity circulating fluidized bed combustion (CFBC) ash and phosphate tailings for the production of a filling material based on the cement. The phosphate tailings were used as aggregate and consolidated by cement and CFBC ash. The results showed that the bleeding rate and fluidity of all mixtures decreased with the increasing the amount of CFBC ash. The fluidity of filling slurry is highly related to the experimental factors such as the content of sulfur solid ash, B/A ratio, and mass concentration. The replacement of CFBC ash ranging from 20 to 40% led to a significant decrease in setting time and an obvious increase in compressive strength, but the above effect was obviously weakened when reducing the mass concentration and B/A ratio. The hydrated calcium silicate gel and ettringite generated from the hydration of cement and CFBC ash were the main sources of strength for the filling materials. When the recommended proportion was 1/6 binder/phosphorus tailings ratio, 76% solid content, and 40% CFBC ash replacement, the filling material still met demands on working and mechanical properties; at the same time, the utilization of CFBC ash and phosphorus tailings was maximized.

Oct 11, 2021

By U. Thorley

This paper presents an overview of surface mining activity in the Canadian oil sands and how the mine operators interact with the province of Alberta's Mine Financial Security Program (MFSP), which took effect April 1, 2011. The MFSP approach to reclamation assurance results in the government of Alberta sharing a portion of reclamation liability through the majority of an oil sand mine's life. In order to determine the potential fiscal magnitude of this shared liability, an examination of the expected costs of oil sands reclamation activities through a study of corporate asset retirement obligation (ARO) liabilities and other corporate disclosures is presented. The province of Alberta's Environmental Protection Security Fund (EPSF), which formerly secured oil sands mine reclamation activities is discussed. Reclamation costs in the oil sands are poorly understood. The MFSP provides what it characterizes as a conservative estimate of C$75,000/ha, while corporate disclosures by Canadian Oil Sands Ltd. place expected costs at C$180,000/ha. There is significant risk associated with the apparent uncertainty surrounding reclamation costs.

Jan 1, 2012

In recent years, Computational Fluid Dynamics, CFD, has been commonly utilized in the mining industry to model the fluid flow behavior in underground mine workings. This paper uses CFD modeling to simulate the airflow behavior in underground crosscut regions, where brattice sails are used to direct the airflow into these regions. Brattice sails are cost effective ventilation control devices for temporary or permanent use in underground mining. They can be used to deflect air into the unventilated areas such as crosscut regions. Their design and installation is a fundamental issue for maintaining a sufficient supply of fresh air and achieving effective air circulation and contaminant removal. At the same time, they should have little impact on the mine ventilation system. This paper presents the results of a two-dimensional CFD model, which examines the effects of brattice length on fluid flow behavior in the crosscut regions. The results of this study will assist in understanding the ventilation air behavior and in determining the optimum size of brattice curtain (sails), which provide a highly effective contaminant removal from the unventilated mine areas. This, in turn, helps the mine ventilation designers to meet the mine safety requirements.

Jan 1, 2009

By Edward P. Larsen

At our annual meeting in St, Louis, Mo. in February 1961, we presented a comprehensive paper (No. 61-B-22) on the subject of "Blending and Handling of Materials for Agglomeration". In that paper you will find a discussion on the difference between "blending" and "mixing". With regard to "blending" we brought out the facts of its usefulness for the preparation o materials in an agglomerated mass to attain controlled chemical and physical uniformity. "Mixing" was discredited as not being useful for the attainment of uniformity of any kind.

Jan 1, 1962

By Se-joon Kim, Jong-hwa Chun

"‘Gas hydrate’ is the common term for a solid material formed from the combination of various gases as ‘guest’ and water as ‘host’. A series of large-scale scientific drilling and coring programmes conducted since 2000 revealed that natural gas hydrate exists in a wide variety of accumulations in the sediments. The scaled-up onshore and offshore field production tests during the last decade show that gas production technology will be realized to make gas production from gas hydrates viable in the future, recognizing its potentials as one of the future sustainable energy resources.The total produced gas was approximately 470 m3 by the hot water circulation method over 6 days of operation in the permafrost-associated Mallik 2002 project in the Mackenzie Delta of Canada. In the Mallik 2007-2008 project, the gas was successfully produced stably by the depressurization method for 6 days, up to 13,000 m3 cumulatively. The depressurization method applied in the Mallik test was shown to be an effective way to produce gas from gas hydrates. The Alaska field trial to inject mixed gas of CO2 and N2 to exchange CH4 in 2012 was successfully done for the first time to produce maximum 1,270 m3 per day. A remarkable achievement was made by Japan when it completed its first offshore production test in the Eastern Nankai Trough, producing approximately 120,000 m3 of methane by the depressurization method over 6 days in March 2013. The technical challenges and scientific uncertainties obtained from Nankai Trough production test provide Korea with more considerations as to the aspects of well completion, reservoir formation and seafloor stability, sand control, flow assurance, environmental monitoring, and etc., due to the different geological setting and geomechanical properties of the Ulleung Basin in Korea."

Sep 1, 2014

By I. Nimmo

Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. Communications issues were resolved, better coordination of materials, improved situation awareness during startups, abnormal operations and an opportunity to make improvements during normal operations characterize the changes at the Worsley Refinery. This presentation will review the reasons for the change. Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. This presentation will review the reasons for the change, what changed and the process of changing the culture from reactive to predictive and what difference that has made.

Jan 1, 2011

In this paper, uniaxial compression tests were conducted on intact rocks and broken rocks that were reinforced by grouting, and the effects of grouting on the strength of broken rocks were analyzed. The results show that after grouting reinforcement, the bearing capacity of broken rocks with different lithologies increased, and their uniaxial compressive strength recovered by approximately 6%–16%. The results indicated that the stronger the rock, the smaller the strength recovery of the consolidated body formed after grouting. At the same time, using borehole camera observation and deep overburden strata separations, the fracture development characteristics of surrounding rocks of the gob-side retained entry were analyzed and divided into different regions. On this basis, a guided grouting method was proposed; that is, shallow hole grouting was first used in the plastic zone of the broken surrounding rocks to form the isolation layer, and then deep grouting holes were arranged in the elastic-plastic zone of the transition zone to guide the slurry flow to the shallow unfilled zone. Therefore, the broken surrounding rocks were reinforced into an integrated body and selfbearing capacity improved.

Jul 28, 2020

By M. van Elp, R. Saitua Nistal, P. J. M. Groot

Demand for construction raw materials depends on investment in housing, other buildings and infrastructure. The provision of these materials requires early knowledge of future trends in construction investment. By using scenarios possible future developments and bandwidths can be explored. Policy makers in government organisations as well as in the private sector can base their policy decisions upon these insights. In this paper we discuss the case of sand and gravel in the Netherlands. We will show that, depending on the future role of government and the degree of internationalisation, the long term demand for construction raw materials will strongly diverge. Nevertheless there are some common developments such as a decreasing population growth, a smaller share of the labour force in total population and a growing wealth. In different scenarios we will encounter different conditions for minerals provision and for sustainable development.

Jan 1, 2011

By T. C. Pool

Physical and chemical conditions permitting, in-situ leaching (ISL) of uranium offers a variety of advantages over conventional production methods including less surface disturbance and less solid waste. Commercial production of uranium by in-situ leaching techniques was initiated in 1963 in the Shirley Basin of Wyoming by Utah Construction. On a world-wide basis, ISL uranium production amounted to about 13.2 million pounds U3O8 in1999, approximately 16% of world output. Both acid and alkaline systems are used, the selection of which is primarily dependent upon groundwater quality and related reclamation requirements. ISL offers low capital costs per unit of annual capacity and is particularly flexible in adapting to changing market conditions.

Jan 1, 2000

By W. R. Reed

The National Institute for Occupational Safety and Health (NIOSH) uses light-scattering dust monitors (nephelometers) in its research to develop dust controls to reduce respirable silica dust overexposures in miners. Recently, the model 1500-pDR, an active nephelometer, was introduced by Thermo Scientific. Testing was completed to ensure compatibility with the metal/nonmetal mine dust personal sampling unit (M/NMDPSU). Results of testing demonstrated that gravimetric concentrations measured from the 1500-pDR are comparable to the gravimetric concentrations measured using the M/NMDPSU, without need for correction, under commonly observed dust loading conditions.

Jan 1, 2012

By J. E. Friant

Until 1956, drill and blast was the only way to excavate rock. In that year, a tunneling machine using disc type cutters economically bored a small Toronto tunnel. Its amazing 105 ft/day set a new world record and set the stage for a new industry. The Disc Cutter Role in Excavation Mechanical excavation of hard rock is by now deeply ensconced in the heavy civil construction industry. All over the world, from the Swiss Alp Melange to Hong Kong Granite, to New York Gneiss, huge Tunneling Boring Machines (TBMs) create transportation, water and sewer tunnels. Powerful machines, boasting as much as 6000 hp, bore through rock, excavating in excess of 1400 tons per hour. The tool that makes this tunneling phenomenon possible is the single blade, rolling disc cutter. These hardened steel discs, from 15 1/2 to 19 inches diameter are arranged on a rotating cutterhead, to cut concentric circles in the rock. As the machine is propelled forward under great pressure, rock below each cutter is crushed. But the efficiency of the cutterhead is derived from the science of cutter spacing (distance between cutter paths). The majority of the rock excavated is not crushed, but flakes off in chips and chunks. No pick, tooth, or drag type cutting tool can duplicate the performance of a disc cutter. The economic use of drag type tools is limited to as low as 5,000 psi UCS rock strength in massive formations. In weakly bonded, foliated rock, drag tools do better, but are still limited to rock generally less than 15,000 psi.

Jan 1, 2002