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By Xiaodong Ma, Marek Pawlik

Introduction Guar gum is a natural nonionic polysaccharide. Guaran, the functional polysaccharide in guar gum is a chain of (1?4)-linked ß-D-mannopyranose units with a-D-galactopyranose units connected to the mannose backbone through (1?6) glycosidic linkages. The poly-mannose chain is randomly substituted with galactose units at a mannose-to-galactose ratio of 1.8-1.0 [1]. Cheng et al. reported that the molecular weight of natural guar gum is 1.935 • 106 [2]. Robinson et al. found that the molecular weights of five grades of commercial guar gums ranged from 4.4 • 105 to 16.5 • 105 [3]. Guar gum is frequently used as a depressant of naturally hydrophobic gangue minerals (e.g. talc) in the flotation of PGM-bearing ores, and according to Harris et al. a wide variety of modified guar gums are available for this application [4]. The Canadian potash industry utilizes natural guar gum as a blinder of water-insoluble slimes in the flotation of potash (sylvinite) ores, a process that is carried out in a saturated KCl/NaCl brine. The role of the polysaccharide is to prevent a primary amine collector from adsorbing onto these unwanted fine minerals. Hydrophobic interactions between basal cleavage planes and the polymer appear to be involved in guar gum adsorption on talc [5,6]. Liu and Laskowski stressed the importance of metal impurities on mineral surfaces that can serve as the active sites for polysaccharide adsorption [7]. This postulate was consistent with the later observation that, in addition to hydrogen bonding, the adsorption of guar gum onto talc was strongly dependent on the surface concentration of magnesium sites [8,9]. In this case the adsorption process was visualized as metal-polysaccharide complexation facilitated by the cis-configuration of the hydroxyl groups of mannose monomers. Hydrogen bonding and chemical interactions with metal sites were also suggested by Rath and Subramanian in their studies on guar gum adsorption on biotite mica [10]. In a recent study, Wang et al. demonstrated that hydrogen bonding is the main driving force behind guar gum adsorption onto talc [11]. Their data also show that the adsorption density of guar gum on alumina is about five times lower than the adsorption density on talc. Pawlik and Laskowski reported that the amount of guar gum adsorbed on illite was independent of ionic strength over a wide range of salt concentrations [12]. The adsorption density of the polysaccharide on illite did not measurably change with ionic strength from that of distilled water to about 50%-saturated KCl/NaCl potash brine (~3N KCl/NaCl). However, guar gum adsorption on dolomite dramatically decreased over the same range of ionic strengths, and no reliable explanation of that phenomenon was proposed [12]. The water structure-breaking or structure-making capabilities of background ions are usually ignored when discussing adsorption mechanisms of polymers. The concept of “structure breakers” and “structure makers” was first introduced by Gurney, and Frank and Wen who postulated that each ion is surrounded by three distinct regions of water structure [13,14]. In the first layer, water molecules are tightly bound to the ion. The second region extends farther away from the ion and is referred to as the region of structure breaking. Only at larger distances, where the ionic field is weak, water molecules form the “normal” ice-like structure. It is also now recognized that the first layer can be further divided into the primary and secondary hydration shells. Small, strongly hydrated ions reinforce the “normal” structure of water and the region of structure breaking disappears. In contrast, large less-hydrated ions disturb the ice-like structure and generate an extensive region of structure breaking. Experimentally, these two effects can readily be distinguished through viscosity measurements. Increasing concentrations of structure-breaking ions result in a decrease of the viscosity of aqueous solutions. On the other hand, increasing amounts of structure-makers significantly reduce the viscosity of water. Alkali metal cations form a sequence known as the Hofmeister series. The Hofmeister series - Cs+, K+, Na+, Li+ - orders the cations from the least hydrated to the most hydrated. Based on literature viscosity data for aqueous

Jan 1, 2005

By L. Tonc

In 2004, the engineers at the Deer Creek Mine located near Huntington, Utah initiated the ventilation planning to exploit a remote area of the mine?s reserves. This area was located under a mountain which would not allow for the incorporation of an additional shaft or portal access near the proposed longwall panels. With this constraint along with the desire to maintain a two entry gate road system and the expected condition of frequent coal wash outs a ventilation plan was established. Different options were examined that included; increasing the current exhaust fan power, adding another exhaust fan installation, converting the ventilation fans in the active portion of the mine to a forcing system, and modifying the ventilation system in the active area of the mine to a push-pull system. The push-pull ventilation system was ultimately selected. This paper details the design process of the ventilation system upgrade, the procurement process for the new fans, and the new fan startup testing.

Jan 1, 2009

By K. E. Wood, K. J. DiRocco, L. A. Becker

The Russia Wharf segment of the Silver Line Phase II Project for the MBTA incorporated ground freezing and underpinning during New Austrian Tunneling Method(NATM) tunneling through timber pile foundations, urban fill, and abandoned wharf structures beneath two historic 7-story buildings with steel frames and masonry facades. During construction, the project team implemented an extensive program to monitor, evaluate, and mitigate the ground and building movements caused by the various construction activities. Mitigation included freeze cycling and building raising/lowering to compensate for ground movements and safely maintain the serviceability and occupancy of the buildings. In this paper, we present the history of the freeze, tunnel construction, and thaw-related movements that occurred and the building response that we observed.

Jan 1, 2005

By Steve Kral

The mining industry is no stranger to hard times. Throughout its history, the industry has faced the ups and downs of commodity prices, difficult-to-mine-and-process ore bodies, labor issues and other problems. Throughout it all, though, the mining industry continues to provide the materials needed for society —even in the face of attacks by those who seek to cripple the industry or have it go away. The reason the mining industry survives, of course, is that mankind requires the products the industry produces. And, in recent decades, the industry has developed new technologies and improved on existing ones to produce those products in environmentally sound ways. At the same time, the economic benefits have been enormous to communities throughout the world where mining takes place.

Jan 1, 2002

By James J. Graham

Uravan, Ambrosia Lake, Gas Hills and South Texas are all historic names in US uranium. These mining areas supplied the uranium that brought the United States into the nuclear age during the 1960s, and fueled the birth of nuclear energy for peaceful uses — a promise of nearly limitless, clean energy for the world’s future. That promise still exists today, but it is hard to hear over the rhetoric of environmental activists and politicians. Nuclear power offers dependable electricity with limited environmental impact at stable prices. Nuclear power releases no greenhouse gases or particulate matter into the atmosphere. High level nuclear waste (HLW), although long lived, is readily controlled and compact. In the United States, generating 1 billion kWh of electricity with coal produces 47 kt (52,000 st) of solid waste (ash and sludge), compared to 3.6 t (4 st) of HLW produced by nuclear.

Jan 1, 2002

By L. Xinghua

Limonite is a general term for a group of amorphous iron oxide and iron hydroxide materials. It is considered as one of the very refractory iron ore types due to its wide variation in chemical composition, iron content, moisture content and easily sliming in the course of comminution. Iron grade of test sample is 25.48%, the iron minerals are mainly limonite; and the gangue minerals consist of quartz and feldspar in majority, secondarily silicate minerals. In this test work, high intensity magnetic separation (HIMS)-cationic reverse flotation and magnetic roasting-low intensity magnetic separation (LIMS) tests were conducted on limonite ore. The test results show that the concentrate with iron grade of 50.97% and recovery of 68.50% can be obtained by HIMS-cationic reverse flotation technique; while using magnetic roasting-LIMS technique, the better concentrate indexes of iron grade of 60.36% and recovery of 89.71% are achieved, and the iron grade of tailing is only 4.42%. Therefore, the magnetic roasting-LIMS technique is a better suitable method for beneficiation of low-grade limonite ore. Keywords: Low-grade limonite; Mineralogy; HIMS; Cationic reverse flotation; Magnetic roasting; LIMS

Feb 27, 2013

By J. Harrison Daniel

Were the legislators and politicians responsible for the closing of the U.S. Department of the Interior?s Bureau of Mines (Bureau) in March 1996 fully aware of what they were doing? Throughout the United States? history, the domestic mining and minerals industry has been largely responsible for the nation?s growth and prosperity that had made it a world leader. The mining and minerals industry made it possible for the young nation to catch up with Europe during the Industrial Revolution, played an essential role leading to victories in World Wars I and II and was a core ingredient for continued economic growth. For a number of decades, America?s import dependency on non-fuel mineral materials has continued to increase. (USGS Mineral Commodity Summaries). Developing domestic resources to meet current and future demands ? particularly those resources considered to be of strategic and critical value to national security ? is necessary. Federal involvement is required since many of these resources are located on public lands. Another reason for federal involvement is that the success of the industry depends on long-range research programs and advances that may take up to 25 years to become commercially available. This situation requires federal partnership to coordinate the programs necessary to collectively involve the industry, individual mining companies and colleges and universities. So, how was it possible to close a federal agency that had contributed so much to the nation?s welfare in a mandated 90-day period, with more than 1,200 employees losing their jobs?

Jan 4, 2010

By Darrell Gillis

Recent accidents in the United States underground Coal Mines and the on-going carnage in Underground Chinese Coal Mines has shown the danger associated with the lack of communication infrastructures in an underground environment. The US Mine Safety and Health Administration (MSHA) have introduced legislation that states all Underground Coal Mines must have two-way voice and personnel tracking capabilities by 2009. If Coal Mining companies are being forced to deal with this problem Tunneling Companies will not be far behind. This paper will examine current practices and best case technology to deal with these issues.

Jan 1, 2007

By R. H. Zeng

Many subsidence researchers in the U. S. have developed new empirical function methods to predict subsidence, or attempted to validate some empirical functions developed by foreign researchers for use in the U. S. An attempt is made in this paper to develop a new empirical function to predict a surface subsidence basin due to longwall mining. In the U. S., the emphasis of empirical methods for the subsidence prediction over longwall panels has been in large part on determining the profile functions for the major cross-sections of a subsidence basin. In this approach, the surface monuments are usually laid out along the major cross-sections and thus, the subsidence profiles developed are restricted for subsidence prediction along the major cross-sections. However in practice many monuments or surface structures for which subsidence prediction for damage evaluation is required, are not laid out along the major cross-section of the basin. In such cases, it is difficult to get either the empirical profile function for the cross-sections where these structures are located or to predict their subsidence based on the profile function developed for the major cross-sections. Therefore, there exists a strong need to develop a subsidence basin function with a reasonable degree of accuracy, which can be determined or confirmed by the data of scattered monuments on a surface basin. The same subsidence basin function can also be used for prediction of subsidence for any arbitrary points over a longwall panel. In 1982, He (1) proposed the clastic theory, for which he developed the basic differential equations describing the movement and deformation of overburden due to underground mining, and performed the selection of best solution for the equations. He found that the Weibull dietribution is the optimal solution. The Weibull distribution has three parameters that vary to fit the subsidence profile so well that the profile function derived from it provides a high degree of accuracy in subeidence prediction. However the results

Jan 1, 1986

By Samer Sadek

The Georgia Department of Transportation (GDOT) undertook an exploratory feasibility study to one of the most ambitious tunneling projects in the United States. HNTB Corporation was retained to perform the study, deemed the Atlanta North-South Tunnel, which is approximately 7 miles long and consisting of four lanes (or six lanes) starting at the southern terminus of SR 400 extending to the south connecting with the northern terminus of I-675, providing substantial relief to the Downtown Connector (I-75/I-85), the most congested portion of Atlanta?s freeway system. This paper summarizes the analysis performed during the first phase of this challenging assignment which, if constructed, would be one of the longest roadway tunnels ever built in the United States.

By A. D. S. Gillies

Diesel engine particulate matter pollution is a matter of concern currently in underground mines worldwide. A number of real-time Diesel Particulate Matter (DPM) monitors have been developed in recent years; two of these by the National Institute of Occupational Health and Safety (NIOSH) in the US. One, the D-PDM, is based on an adaption of the successful NIOSH?s Personal Dust Monitor (PDM) unit which is being taken up very successfully for mine respirable dust monitoring. The D-PDM measures all particulate matter within a sub-micron range as classified nominally at 0.8 micrometers by a purpose developed cyclone. The other, the FLIR Airtec, measures the Elemental Carbon (EC) component of DPM by a laser scattering approach. Both instruments have been evaluated underground in robustness and reliability testing in coal mines by the authors. Real time DPM monitors allow greater understanding of the sources and levels of DPM pollution in underground activities. They allow engineering evaluations to determine how conditions can be improved or mining personnel relocated to lower concentration levels. Studies are discussed that examine DPM concentrations from vehicles under varying ventilation conditions. Some of these concern tests undertaken during high activity longwall face moves. They focus on evaluating DPM during the various phases of the face Chock Shield moves. An initiative in some mines has been to limit the number of vehicles in the mining section or panel by the use of a Tag Board or Traffic Controller at the panel travel road entrance to manage exhaust DPM and gases. Diesel tags or tokens are used to control the number of vehicles entering a section or panel and so limit level of pollution. Summation of DPM levels from points monitored throughout a panel demonstrates increasing DPM levels from influence of additional equipment in series within the ventilation circuit. An alternative approach is to invest in underground continuous real-time monitoring of exhaust gases, DPM and section air quantity and integrate this information to determine whether an additional vehicle can enter without exceeding diesel target limit. This optimizes the access of diesel vehicles and replaces the existing manual tag board system. Real-time DPM monitoring allows the industry to pin-point high exposure zones such as those encountered where various vehicles work in areas of constrained or difficult ventilation. Identification of high DPM zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce underground miners? exposures.

Jan 1, 2012

By N. Abdel-Khalek, A. Youssef

The tailings from beneficiation of Florida phosphate ore contain considerable phosphate values. These tailings are currently discharged into large disposal areas. More than three million tons of P2O5 are discarded with the phosphatic slimes (clays) in Florida each year. These phosphatic clays not only create one of the most difficult disposal problems in the mining industry, but also represent a tremendous loss of P2O5. As the quality and quantity of Florida’s phosphate reserves diminish, recovery of phosphate values from these wastes becomes more vital. This will also significantly lengthen the life of these important phosphate resources. Thus, it is the goal of this study is to recover more than 80% of the phosphate values in phosphatic clays. A systematic study to characterize samples taken from inactive disposal area has been conducted. The data suggest that natural segregation takes place in the settling pond. In other words, coarser particles settle closer to the feeding point of the pond. Flotation tests were conducted using the +325 mesh fraction of samples obtained from sites close to the feeding point (sample# A) and further from that point (sample# B) and (sample# C) which is even further away from the feeding point. The results show the following: Sample# A gives the highest grade and recovery, followed by that of # B and then of # C. There is a great potential to upgrade sample# A where concentrates of high grade (68.9-70.1 % BPL or 31.5- 32.1% P2O5) and recovery (~86.6-95.4 %) can be obtained under the investigated operating conditions (1.0 – 2.0 kg/ton sodium silicate and 1.5—3.0 kg/ton collector mixture of fatty acid and fuel oil). The mineralogical and chemical analysis of all samples is presented in this paper for comparison. Only in this paper, the flotation data of (site # A) are discussed below.

Jan 1, 2002

By Robert J. Timko, Charles D. Taylor, Edward D. Thimons, Tom Mal

A test system was developed for measuring airflow in the National Institute for Occupational Safety and Health (NIOSH) ventilation gallery using a three-axis ultrasonic anemometer. The gallery was used to simulate face airflow conditions in underground mines having a blowing curtain. Airflow data collected at multiple sampling locations between the face and the end of the curtain were used to draw airflow profiles for different curtain setback distances, intake flow quantities and entry widths. In addition, methane was released at the face, measured at the sampling locations, and displayed as methane distribution in the area between the curtain and the face. Entry geometry had a significant effect on airflow patterns, and the flow patterns affected the distribution of methane in the entry. Flow measured at and parallel to the face was a good predictor of methane dilution and removal within two feet of the face.

Jan 1, 2005

By Vince Luongo

PROJECT DESCRIPTION The York Durham Sanitary System (YDSS) Interceptor in the Town of Richmond Hill located just north of Toronto, Ontario, Canada will see the construction of a tunnel extending along 19th Avenue for a length of approximately 3.8 Km from Yonge Street, east to Leslie Street and will have a minimum internal diameter of 2.1 m. t to Leslie Street and will have a minimum internal diameter of 2.1 m. The tunnel will connect into four shafts, for which two of the shafts will be constructed using the slurry wall construction method given the high water table and difficult ground conditions encountered at these locations. The two shafts noted as Access Shaft No. 2 and No. 3 were designed and constructed to meet regulatory conditions, which required a sealed shaft construction method. GEOGRAPHICAL PROFILE The ground conditions in the Toronto region consist predominately of glacial till, glaciolacustrine and glaciofluvial sand, silt and clay deposits, and beach sands and gravels. The shallow geological formation found in the project area consists of four types of deposits: Oak Ridge Morain deposits, Halton Till, Glacial lake deposits and Organic soils. The Oak Ridge Morain is the dominant deposit encountered along the tunnel alignment. This formation consists of three deposits: The Upper Till, Middle Sand and the Lower Till. Standard penetration tests (SPT) carried out in these deposits measured N-values ranging from 2 to more than 100 blows/300mm which indicate very loose to very dense soil conditions. The Middle Sand deposit will be the dominant feature within the slurry wall construction at access shafts 2 and 3. Access Shaft 3 The base of the slurry wall will be 20.5 M below the ground surface. Slurry wall excavation will be within peat and organic soils found at the upper 3 M, followed by 5 M of the Upper Till. The remainder of the excavation will be within the Middle Sand. The piezometric head elevation is found at the ground surface. Access Shaft 2 The base of the slurry wall will be 22.5 M below the ground surface. Slurry wall excavation will be entirely within the Middle Sand 2.The piezometric head elevation is found at 7 M below the ground surface.

Jan 1, 2007

By Silvano Morelli, Giovanna Cassani, Renzo Bindi, Antonio Nicola

More than 70 km of main line and service tunnels have been excavated to date for crossing the Apennines between Bologna and Florence. A new design and construction approach, known as Analysis of the Controlled Deformation in Rock and Soils, (ADECO-RS), was adopted to tackle the extreme heterogeneity of the ground and the particular stress-strain conditions. The goal of this system is to obtain constant and predictable full section advance rates, even in very poor geology, with the highest possible level of safety and reliability. The execution of this gigantic project required the mobilization of 21 job-sites, with the concurrent operation of 30 excavation headings. The global production rates confirm the high quality of the design and the high level of industrialization reached during the construction stage, levels not previously obtained in similar conditions, using other approaches such as NATM.

Jan 1, 2003

By Roozbeh Afzali

Designing an appropriate tunnel blasting pattern reduces the cost of rock breakage and subsequent operations such as loading, haulage and support of tunnels. For that reason, we developed a software that designs tunnel blasting patterns. Using this software, three different tunnel blast design models based on parallel hole cut, namely, Swedish, Konya and Energy Balance, were investigated and compared for a virtual tunnel. Accordingly, blasting patterns were designed, for different cross sections. The trend of parameters such as specific charge and specific drilling as functions of tunnel cross-section was determined for each model. Our results show that, in general, The Swedish model gives lower specific charge and specific drilling compared to other models.

Jan 1, 2008

By K. P. Black, G. W. Sevick, D. E. Hockley, K. S. Sexsmith, J. T. Chapman

Mineralogical analyses of carbonates in depyritized tailings and pyrite concentrate (from depyritization of the tailings) were completed as part of the tailings characterization for the Crandon Project, a massive sulfide deposit in northeastern Wisconsin. The mineralogical study was designed to determine the proportion of calcium and magnesium carbonates, and therefore the effective buffering capacity of carbonates in the tailings. The depyritized tailings are net acid consuming and will be stored in a surface tailings management area. The pyrite concentrate is net acid generating and will be used as backfill in the underground mine workings. The majority of carbonates in the depyritized tailings were ferroan dolomite containing 10 to 15% iron (by weight) and lesser amounts of siderite and magnesian siderite. The proportion of calcium and magnesium-rich carbonates corresponds to several independent tests of carbonate neutralization potential (CO3-NP) availability. The pyrite concentrate had less CO3-NP, indicating segregation of the carbonates during pyrite flotation. These carbonates reported higher iron contents, consistent with the relatively lower availability of CO3-NP in the pyrite concentrate.

Jan 1, 2002

By D. Conklin

Annual fish monitoring of the Red River, NM from the town of Red River to downstream of Questa, NM has been conducted since 1997. This long-term dataset, sponsored by the Chevron Mining Inc. Questa Mine provides an opportunity to evaluate the fish community response to natural phenomena, such as landslides and drought. Hydrothermal scars are present on drainages to the Red River, which can contribute large quantities of sediment to the Red River during localized storm events. Sediment inputs from the hydrothermal scars result in decreased habitat and water quality conditions within the Red River. Landslides from the hydrothermal scars contributed large amounts of sediment to the Red River in the summers of 2002 and 2007. Resident trout populations in the Red River after summer 2002 were depressed at sites adjacent to and downstream of the hydrothermal scars. Resident trout populations had begun to recover by 2005 and 2006; however, after the summer 2007 landslide, the resident trout population was again drastically reduced. In fall 2007, 13 resident trout were collected from 11 sites in the approximately 23 km reach of the river, compared to 691 from the same 11 sites in fall 2006. Resident trout density and biomass has gradually increased since fall 2007, and flows have removed sediment from the study reach. A combination of increased sedimentation and decreased water quality were likely responsible for the decreased resident trout populations in the Red River. Drought and the lack of flushing flows appeared to exacerbate the problem of high sedimentation levels from 2001 to 2004. Climate models predict prolonged periods of drought and increased intensity of storm events, potentially resulting in less favorable conditions for the resident trout population of the Red River in this area.

Jan 1, 2011

By P. M. Prasad

Off-grade molybdenite concentrates, mainly derived from secondary sources as by-products of the processing of copper, uranium and tungsten ores, do not satisfy the purity requirements (percent MoS2) for the production of molybdenum bearing products. This investigation is a continuation of a successful effort to refine a low-grade molybdenite concentrate to prepare a high-grade MoS2 using a mixed acid (HF + HCl) leach procedure. Specifically, this investigation is concerned with an understanding of the separation chemistry underlying the removal of the oxide/silicate gangue and the base-metal sulfide associations present in the low-grade molybdenite by their selective dissolution in the two acids. Experiments were conducted on an off-grade concentrate containing 42.6% Mo. Results of the controlled dissolution tests indicate that both HCl and HF are suitable for the removal of the associated alumina and both work well for iron, nickel and copper. However, HF was found to be the most effective for dissolving silica/silicate and magnesia. An attempt was made to rank the leaching efficiencies of the acids used singly, sequentially or in a mixed mode. Scale-up (300 to 2,000 g) experiments were conducted to validate this approach. Excellent purification of the concentrate was possible by processing the off-grade concentrate with 10% HCl plus 15% HF at 363 K for 7.2 ks in open polypropylene reactors with internal stirring. These conditions leached practically all of the oxide and silicate gangue and 96% of the metallic impurities. Starting from the low-grade molybdenite concentrate (42.6% Mo; 71.1% MoS2) it was found feasible to obtain a refined product containing 97.8% MoS2, which is suitable for industrial use.

Jan 1, 2007

By M. Moagabo

CO2 emissions from carbonate laden reclaimed mine spoil has been shown to pose a hazard to residents in homes built on or adjacent to such land. The objective of this project was to develop a soil CO2 flux survey protocol for assessing reclaimed mine land. The research involved CO2 chamber accumulation flux surveys; stable carbon isotope ratio analysis; statistical hypothesis testing to examine correlation between CO2 flux and soil temperature and moisture as well as spatial dependence; and geostatistics to map CO2 and delineate high flux zones. Soil temperature was observed to have a positive correlation with fluxes while soil moisture was observed to be negatively correlated. Spatial dependence of CO2 fluxes on reclaimed mine land was observed on one of the two study sites. The research suggests that macro-porosity and gas permeability may be important factors that explain CO2 migration in mine spoil. A flux survey protocol has been developed, based on these results, for reclaimed mine lands. The work demonstrates the capability of geostatistical methods to delineate high flux fields. Further research will be required to determine suitable thresholds for such analysis.

Jan 1, 2012