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By David Newman

"Horizontal stress can have a profound effect on the stability of an underground limestone mine. The presence of horizontal stress is usually determined once the mine has been developed and the orientation of headers and crosscuts are well established. Multiple attempts are typically made to control roof falls without re-orienting the mine. Once the decision has been made to change the orientation, pillar centers, mine opening widths, and the question of how to determine the correct orientation must be answered.A case history is presented to illustrate how geologic structure, ground conditions and roof falls in adjacent mines, the World Stress Map (Heidbach et al., 2016), in-mine measurement of “cutter” roof orientation, the orientation of strata offset (cats eyes) within borescope holes, and the diametral deviation method of determining horizontal strain from drill core were used to establish the most likely range of horizontal stress.The main headers were re-orientated in a direction parallel to the median of the range of horizontal stress. The crosscuts were angled 60° to the headers to avoid being perpendicular to the horizontal stress direction. Pillar centers and opening widths were increased in the favorable stress direction of the mains and decreased in the less favorable crosscut orientation. The major principal horizontal stress magnitude was estimated using the strain measurements from the diametral deviation method and elastic modulus obtained through testing.INTRODUCTIONOver the past decade, there has been a significant increase in the number of underground stone mining operations in the United States. As stripping ratios at surface quarries become uneconomical and reach the extent of the mineral boundary, coupled with the encroachment of urban development on previously rural mining operations, the remaining mine reserves are best accessed through underground development.Although the majority of underground limestone mines in the Midwest are in relatively flat lying deposits with minimal geologic structure, many Appalachian mines are in folded and faulted environments. Tectonic horizontal stresses associated with multiple orogenic episodes are locked in the formation and are released as the underground mine is developed.A common misconception is that horizontal stress impacts are more prevalent at shallow depths where the ratio of horizontal to vertical stress may be high. However, field observations and academic research indicates that horizontal stress conditions may be encountered at any depth due to the tectonic compression of the limestone formation (Esterhuizen et al., 2007; Dolinar and Esterhuizen, 2007; Iannacchione et al., 2003; Slaker, Murphy, and Miller, 2017; Kuhnhein and Ramer, 2004). This paper outlines mine design and layout guidelines for the mitigation of horizontal stress impacts on underground stone mining operations through a case history example. This approach to mine planning and the ability to anticipate horizontal stress can significantly improve future production of multiple levels (Newman and Newman, 2019). As underground stone production continues at deeper depths and in more geologically and geometrically complex mining conditions, an emphasis on ground control and the anticipation of horizontal stress can provide safer and more productive single and multiple level mining operations."

Jan 1, 2019

By A. H. Farazi, C. Quamruzzaman

The freezing and subsequent solidifying of unstable, weak (sands, silts and clays) and/or wet soil to form a desired-shape frozen barrier around a construction area are possibly the main features of the freezing method for shaft sinking. The barrier, along with strengthening the soil, provides a dry environment to ensure sustainable subsurface construction work before placing a permanent lining. The freezing method requires the installation of freezing pipes in boreholes around the construction area and the circulation of chilled salt water through these pipes and has long been a proven technique for dry shaft sinking through unstable and water-bearing seam around the world. As removing heat from the ground is the main feature of the method, an efficient thermal design of the freezing process is mandatory to ensure success of the shaft sinking operation. This applies to both the sustainability and economy of the intended structure. The design presented in this paper is aimed at figuring out the heat-removing ability and operating time of the refrigerative equipment using some simple formulae. The authors adopted a theoretical approach to determine the quantity of heat to be removed from the ground. The amount of energy for the equipment was found to be greater than that for freezing, which proved the validity of the design. The active freezing period was calculated to be 121 days. The authors followed the structural design of the freezing process they proposed in their previous work (Farazi and Quamruzzaman, 2013). Though the first coal seam in the coalfield was encountered at a depth of approximately 352 m in the subsurface, the target depth for cooling and freezing was decided to be 162 m. The formation demands extra care to nullify its risk of the temporary structure collapsing and water rushing in (Farazi et al., 2012). Discussion on the determination of refrigerative equipment parameters was excluded from the scope of this work.

Jan 1, 2014

By W. Pawlos, A. Bakalarz, M. Duchnowska

This paper presents the results of an investigation into the influence of hydrodynamics on a preflotation process for the copper sulfide ore from the Fore-Sudetic Monocline deposits in Poland in a flotation machine. The main aim of the preflotation stage for Polish copper ore is to remove the easy-to-float organic matter — organic carbon — that causes serious problems in metallurgical processes. The organic matter is connected with the presence of shale ore. This paper describes the preflotation experiments conducted to investigate the effect of various stirrer speeds. The upgrading selectivity of copper and organic carbon were analyzed and compared. The results show that the effectiveness of separation between organic carbon and copper decreases with increased stirrer speed in the laboratory flotation machine. The more intensive the mixing of the flotation suspension, the lower the selectivity of the preflotation experiment. Lower stirrer speed probably provides lower mechanical entrainment and flotation of copper minerals.

By M. S. Safarzadeh

Over the last fifty years, the treatment of enargite concentrates has not received much attention, primarily because of the availability of other clean concentrates suitable for processing with existing smelting and/or leaching technologies. As traditional copper ores have become scarcer, copper-arsenic ore deposits have garnered more interest. Arsenic release is a significant concern during the treatment of enargite concentrates by pyro or hydrometallurgical methods. Enargite is also very refractive in standard leaching procedures. Thus, economical treatment options for enargite concentrates are needed. Preliminary experiments have shown that the acid bake-leach process could be adapted and used for the treatment of enargite concentrates. In this study, low-temperature (100-400º C) sulfuric acid baking of an enargite concentrate followed by water leaching has been evaluated. The results indicate the thermal transformation of enargite to copper sulfate happens during sulfuric acid baking, with most of the arsenic being released from the concentrate into the gas phase when baking at 400º C. The condition for maximum copper extraction (~100%) from the concentrate was found to be 400º C, a sulfuric acid concentration of 0.5 mL/g and two hours baking time. Part of the arsenic was captured in the form of arsenopyrite (FeAsS). X-ray diffraction (XRD) analysis proved the presence of some arsenic in the form of claudetite (As2O3) in the baked concentrate. Acid baking of pure enargite behaved in a similar fashion.

Nov 1, 2011

By Greg Sanders, Bill Lueck, Michael Gilbert, Mahmood Khwaja

"The city of Minneapolis contracted with CDM Smith to update and provide a conceptual design for improvements to mitigate surcharge flooding in the Central City Storm Water Tunnel System (CCSTS). As a part of the project, CDM Smith conducted a field survey and condition assessment of the existing tunnel system. Information from the survey was then used to update the existing XPSWMM model and develop system wide alternatives.The CCSTS provides storm-water runoff drainage for nearly the entire area of the city’s downtown commercial district. The system consists of deep storm-water tunnels constructed in the St. Peter Sandstone, approximately 21 m (70 ft) below the street’s surface. The primary tunnels comprising the Central City storm water tunnel system are located below Hennepin Avenue, Nicollet Mall, Lesalle Avenue, Marquette Avenue South, 2nd Avenue South, South 5th Street, Washington Avenue South, Portland Avenue South, 2nd Street South, and Chicago Avenue South, as shown in Fig. 1. This network of tunnels conveys the runoff from a 305-acre tributary area that is generally bound by Hennepin Avenue and 1st Avenue North to the east, 12th Street to the south, 4th Avenue South and 7th Avenue South to the west, and 2nd Street South. These tunnels were constructed between 1936 and 1940, except for the Marquette Avenue South tunnel, which was constructed between 1963 and 1964.The CCSTS operates as a gravity flow system. These tunnels were constructed within the St. Peter Sandstone layer of bedrock and emerge from the bedrock at the Mississippi River below St. Anthony Falls. The Central City and the adjacent Chicago Avenue tunnel system converge into a single outfall at the Mississippi River. The runoff discharges from the converged outfall to a side channel of the Mississippi River, called a tailrace, located near the Guthrie Theater. The Minneapolis Division of Surface Water and Sewers provided 32 historic plats detailing the plan and profile of the tunnel system.The tunnel plans show nine different cross-section configurations. Eight configurations within the overall system generally show the same geometric “cathedral” shape with the inside dimensions varying from 1.2 to 1.8 m (4 to 6 ft) in width and 1.8 to 2.4 m (6 to 8 ft) in height. For analysis, these eight configurations were reduced to three configurations with regards to tunnel liner, cross-sectional area and support. For simplicity, the three configurations are described according to the three types of tunnel support used during construction: none required, light timber and heavy timber"

Jun 1, 2019

By Robert L. Runkel, D. Kirk Nordstrom, James W. Ball

Low-flow reactive-transport processes in Wightman Fork downstream of the Summitville Mine, south-central Colorado were simulated using the OTIS and OTEQ solute-transport models. The simulation was calibrated using data from a synoptic study conducted during October, 1998. Discharge over the 8-km reach from just below the mine site to the Alamosa River confluence ranged from 0.077 to 0.17 m3/s; travel time was 10.7 hours; pH ranged from 4.6 to 5.7. Simulations revealed that mass balance for SO4 was maintained, and that pH, Fe, and Al were non-conservative. Simulations allowing hydrous ferric and aluminum oxide or hydroxysulfate precipitation matched observed water quality conditions more closely than simulations without precipitation.

Jan 1, 2000

By J. E. Osmanski

This semantically ambiguous title purports to describe an examination of the question of automation and its effect on the industrial worker. More explicit titles might be "Painless Automation" or "Mechanization without a Sting" or, if I may steal a few phrases from the title of a recent interview Pith John L. Lewis, "More Machines, Fewer Men -- Is the Union Happy About It?" Automation has become the biggest ?scare word? for many industrial workers and their unions since "wage stabilization.? "To many a union orator," reports TIME of January 4, "automation is the sinister business of eliminating jobs." TIME might better have phrased this description by saying that many unions regard automation as the attempt to eliminate not jobs, but workers, The recent steel dispute was hung up for so long primarily because of the problems evolved of increased job efficiency through automation and job changes. Everywhere today there is heard the cry of our need for maintaining full employment within the context of an expanding economy echoing against the sheer reality of automation's displacement of thousands of workers through a rapid acceleration of productivity.

Jan 1, 1960

By Hendri Silaen, Charles Leatemia, Monang Napitupulu, John Kamarea, Arwin Edijanto, Riza Hasan, Avesiena Primadiansyah

The Deep Mill Level Zone (DMLZ) is the fourth panel cave mine in the East Ertsberg Skarn System, (EESS) which lies 500 m below the producing Deep Ore Zone (DOZ) mine and up to 1,700 m below the surface. The interaction between the DMLZ and DOZ is occurring as the DMLZ cave grows vertically toward the DOZ footprint. During this process, a rapid change in the global mine system stress is anticipated. This change is forecasted to drive substantial changes in the magnitude and direction of principal stresses in the DMLZ and DOZ mines at PT Freeport Indonesia. These changes will bring the mine system closer to the ultimate capacity of the excavations and can result in significant impacts to mine stability if not managed. Critical to this management, is understanding cave growth and locations, as well as how these changes will impact stress conditions.

Apr 26, 2022

By S. J. Cohen

Changes in our energy, national security, and commerce needs have necessitated identification of new sources of minerals, such as rare earths, lithium, copper, silver, aluminum, titanium, and the minerals on the U.S. Geological Survey’s (USGS) list of critical minerals (USGS, 2022). With the need to domestically produce these minerals, more mining will be required within the U.S. Some of these critical minerals deposit with naturally occurring radioactive materials (NORM), therefore, mining these minerals may concentrate NORM to the point that some states may require licensing and radiation protection programs. NORM is not regulated by the Federal government; it is regulated by the individual states. Consequently, overall national state of NORM regulation is chaotic with each individual state either choosing to regulate or not regulate NORM, and, if a state chooses to regulate NORM, then that state develops its own unique regulations. Further complicating the regulatory environment, states utilize a wide variety of strategies for regulating NORM, which sometimes results in inappropriate regulations, inconsistencies with specific radionuclides that are regulated, and inconsistencies with specific NORM types that are regulated. This paper will review the nature of NORM regulations, identify regulatory traps, and provide general guidance for identifying NORM and potentially avoiding regulatory jeopardy. Because of the chaotic nature of NORM regulations nationally, seeking guidance from qualified professionals with relevant expertise is recommended. Also, contacting the appropriate regulatory agency to gain a complete understanding of the NORM regulatory environment is useful for maintaining compliance.

Feb 1, 2023

By G. Meschke

"This paper reports on computational and experimental research, performed at the Collaborative Research Center “Interaction Models for Mechanized Tunneling” at Ruhr-University Bochum, Germany. Research covers a broad spectrum of topics relevant for mechanized tunneling in soft soil conditions. This includes advances exploration methods and models for the characterization of the in-situ ground conditions, the interaction of the face support and the tail gap grouting with the porous soil, multi-scale models for the design of fiber reinforced segmental linings with enhanced robustness, computational methods for the numerical simulation of the tunnel advancement, the soil excavation and the material transport in the pressure chamber, logistics processes and risk analysis in urban tunneling.INTRODUCTIONMechanized Tunneling has proven itself as an economical and flexible construction method that continues to undergo a dynamic evolution process. Shield diameters continue to increase, and the application range of tunnel boring machines is being extended to an ever-increasing variety of geotechnical conditions. In order to maintain economic viability and to ensure an environmentally friendly construction process, realistic and reliable numerical models are required in order to make informed decisions during planning and construction. To provide a reliable numerical prognosis, it is necessary to accurately assess and understand the interactions between the components involved in mechanized tunneling with the surrounding site, the ground, and any pre-existing structures. Heterogeneous geological conditions and often only approximated ground parameters create, in contrast to other engineering projects, special demands. This necessitates new insights to new problems that can only be effectively solved through truly interdisciplinary research. To address these challenges, the German Research Foundation (DFG) has established the Collaborative Research Center “Interaction Models for Mechanized Tunneling” (SFB 837) at the Ruhr-University in Bochum in 2010. Collaborative Research Centers are interdisciplinary scientific research groups in which cooperative research is conducted under the umbrella of a central research theme. With a research budget of ca. 10 Million Euros for the second 4-year funding period, and a research team composed of 13 project leaders along with approximately 35 scientific assistants the SFB 837 is currently one of the largest research groups conducting fundamental research in tunneling related topics worldwide.RESEARCH TOPICSThe research topics of the SFB 837 encompass a number of relevant planning and construction related aspects in mechanized tunneling (Figure 1). These research themes are each supported by computational models and laboratory investigations and are all included in an SFB overarching Tunnel Information Model (TIM). Interaction groups integrate and combine the results of different submodels through prototypical cause-and-effect relationships, and through the analysis of the Wehrhahn metro line (WHL) project in Düsseldorf, which has been adopted as the reference project for the SFB 837."

Jan 1, 2016

By M. D. Dennis

Precious metal mineralization at Mt. Hamilton" Nevada is associated with a poly-metallic, garnet-pyroxene skarn system developed in middle to upper Cambrian calcareous shales, limestones and dolomites. The skarn is developed around the Cretaceous Seligman and Monte cristo calc-alkaline stocks. Gold is associated with intense retrograde alteration. Later epithermal quartz veins containing gold, silver, base-metal sulfides, and sulfosalts cross-cut skarn alteration. Westmont Mining Inc. is currently developing two mineralized zones containing a geologic resource of approximately 7.7 M.T., which averages 0.05 OPT gold and 0.5 OPT silver. The project will have an estimated mine life of seven years, with a planned annual production rate of 35,000 ounces of gold and 300,000 ounces of silver.

Jan 1, 1989

By David Shuck

On November 1991, Homestake Mining Co. completed the installation of a $5.7-million, 2.7-kt/d (3000-stpd) flotation circuit into the flowsheet of the McLaughlin Mine in California's coastal mountain range, about 113 km (70 miles) north of San Francisco. This addition reduced overall operating costs and improved the gold recovery of the low-grade refractory reserves over that expected from direct cyanidation. In addition, flotation provided a means to generate a sulfide concentrate that is used to supplement feed to the pressure oxidation circuit. The McLaughlin operation started in 1985 as the first pressure oxidation plant for treating sulfide refractory ore. During the mine's short history, efforts have been made to reduce costs and increase production through process development.

Jan 1, 1994

By Hasan Nizamoğlu, Z. Abidin Sarı, Aslıhan Demiraslan, M. Deniz Turan, Tolga Depci

In this study, recovery of copper from solid material (obtained by leaching of chalcopyrite with oxalic acid in the presence of hydrogen peroxide) with a copper oxalate structure was carried out selectively using HCl. The chemical composition of the solid was as 29.3%, 9.7%, and 13.3% for Cu, Fe, and S, respectively. Selective recovery of copper by degrading the copper oxalate structure with a low-solubility product (Ksp = 4.43 × 10−10) was performed by conventional leaching in the presence of HCl. The optimum leaching conditions were determined as 5 M of HCl concentration, 318 K of leaching temperature, 120 min of leaching time, 25 ml/g of liquid–solid ratio and 400 rpm of stirring speed. Under these conditions, approximately 77% of copper and 3% of iron were taken into the solution. According to the characterization of the leach residue that was obtained, the oxalate structure was degraded. Moreover, the results of XRD analysis showed that the sulfur (S) and cubanite (CuFe2S3) phases were mostly observed in leaching residues, and this was supported by the SEM-EDX data. Based on the results, it may be stated that selective copper extraction can be obtained from a chalcopyrite concentrate by a two-step leaching method using a conventional hydrometallurgical technique.

By Kenneth K. Landes

So far my consulting in industrial minerals has been confined principally to carbonate rocks,-salt, coking coal, and glass sand. Much of this work has been for companies either too small for a full-time geological staff or unaware of the value of employing one or more qualified geologists permanently. It gave me considerable personal satisfaction to see several of the latter companies employ one or two full-time geologists after the completion of a consulting contract with them. One possible reason why some companies lack the wisdom to hire geologists is that they are dominated by engineers who still subscribe to the old idea that engineers are self-sufficient in all fields. They could have learned this from their professors. I once knew a Dean of Engineering who got purple in the face when a faculty committee was discussing the financing of a broad gauged engineering project and suggestions were made that assistance be obtained from the Schools of Business and Law and from some of the science departments tie pounded the table and shouted "Engineers are trained to handle all this!" In teaching engineering geology some years ago I used to tell the class repeatedly that the course would not make them geologists, that the purpose was to teach them

Jan 1, 1972

By William Hodder, Ehsan Alavi, Nader Ghasempour, Daniel Cressman

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel (CBT) Project in Toronto will extend approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. The tunnel is currently being mined by using a shielded dual-mode tunnel boring machine (open and close) capable of operating in EPB mode and lined by using a precast concrete segmental tunnel linear with an internal diameter of 6,300 mm and external diameter of 6,900 mm. The CBT is expected to be excavated mainly through shale bedrock of the Georgian Bay Formation, at approximately 50 meters deep. The tunnel crosses a buried bedrock valley in two locations, in the southern portion of the alignment, adjacent to the Don River, and at the northern portion of the alignment approaching the CX-1 shaft. In these two locations, the bedrock cover is expected to be less than 6 meters. The risk of encountering weathered bedrock, significant ground water inflows or surficial soil deposits through these buried valleys was identified during the design phase. The contract required the TBM to be designed with the ability to probe drill ahead of the TBM and convert to EPB mode if necessary, to cross this area. This paper will discuss the additional exploration that was performed by the contractor to identify the extent of this buried valley, the plan going into the zone of potential weathered shale, and the actual conditions encountered.

Jun 13, 2021

By Albert Hofstra, Joel Leventhal

The gray, dark gray and black colors of the sediments and the presence of pyrite in the Carlin, Jerritt Canyon, Horse Canyon, Betze, and Gold Acres sediment-hosted disseminated gold (SHDG) deposits indicate that these rocks are not oxidized with respect to carbon and iron sulfide. Both ore and non-ore host rocks generally are dark colored. Analyses for noncarbonate carbon (usually called organic carbon) in samples from SHDG deposits and related unmineralized rocks indicate that these rocks contain from a few tenths to a few percent carbon. We use the term noncarbonate carbon because, strictly speaking, organic carbon denotes carbon that is bound to hydrogen. However, the carbon present in SHDG deposits and related rocks has very little hydrogen chemically bound to it. Rocks with less than 2% organic carbon are usually gray in color. The dark colors in our samples are due to the relatively high temperatures that these rocks have experienced relative to organic matter maturation. We confirm the results of Nelson et al. (1982) that previous reports (for example, Radtke and Scheiner, 1970) were incorrect in reporting significant amounts of humic acids, extractable hydrocarbons (bitumen) or "carbonaceous" material. We believe these reports had problems with contamination or misdirected emphasis. Our samples consisted of unweathered rocks, collected mainly from mine cuts (benches, trenches, cores) and put into glass containers or wrapped in aluminum foil to avoid contamination. Only a few samples were collected from natural outcrops. We were careful to avoid samples in proximity to blast holes that were packed with ammonium nitrate and diesel fuel ("ANFO"). Contamination by ANFO may explain some of the previous reports of hydrocarbons, pyrobitumens, humic acids and anomalous nitrogen. When we were collecting samples, it was apparent that in addition to lithologic and color differences, the surface appearance of the rocks was distinguishable: "preg robbing" material that had a sooty surface; "graphitic" rock with a shiny surface; and more ordinary rocks that had a flat gray or black appearance. [Preg robbing is a term for ores that adsorb gold from the milling circuit; the graphitic material had not been x-rayed to actually identify graphite.] We hoped that laboratory study of these samples would show some fundamental differences that we could relate to ore genesis. Even though these sample types appeared different in the field, we could not distinguish any differences in thermal maturity (see below). Normal petroleum/organic geochemical laboratory procedures (solvent extraction, Rock-eval, pyrolysis-gas chromatography) failed to yield much information because the carbon was over-mature relative to oil and gas generation. Rock-eval results show less than 20 (± 20) mg of pyrolizable hydrocarbons per gram organic carbon (and an indeterminate Tmax) indicating that the organic matter in these deposits is burned-out relative to petroleum generation [with an H/C (atomic) ratio of less than 0.41. Because of the non-definitive results from standard organic geochemical methods, x-ray diffraction (XRD) and Raman spectroscopy were used to characterize the carbon. Prior to XRD, samples were treated with HCl and HF acids (1) to remove quartz that has a peak near 26° [20] at the position of the 002 peak of graphite and (2) to concentrate the carbon to a level detectable by XRD. The residue was put on a colodion mount and analyzed by XRD. The XRD analyses yielded a broad peak at 26° [20]. The shape of this peak indicates that the carbon is more thermally mature than anthracite rank coal but less mature than crystallized graphite. Based on XRD results from the literature (Landis, 1971) that are calibrated to metamorphic facies, results from our samples correspond to pumpellyite-actinolite to lowermost greenschist facies conditions, probably

Jan 1, 1990

THE FUTUREGEN CLEAN Coal project will be the recipient of $1 billion worth of federal stimulus money by way of the U.S. Department of Energy (DOE), which announced the commitment to the project. The money is expected to kick off years of further work that could finally see the project completed. One of the companies involved, Ameren Corp., said the $1.2 billion project ? which will include some private funding ? still has a number of hurdles to clear.

Jan 1, 2010

By S. A. Braley

Water is our most important natural resource, for without it there is no life. It is also the principal natural resource for all manufacturing processes, in particular for the development of power. For these reasons it is essential that water be protected and conserved, with the realization that its quality 18 as important as the water itself. A significant factor in the quality of ground water is the mining of coal -- that other main ingredient of Power. In the mining of coal it is necessary to disturb the geological strata overlying or adjacent to the coal seam. This procedure not only releases water from water-bearing strata or underground aquifers but also exposes other minerals which eventually become the source of pollution or deterioration of the released water as well as of the surface stream into which It is discharged It is then evident that in attempting to utilize one essential natural resource there is degradation of the quality of the other. Many selfishly assume that the principal function of a stream is fishing and recreation, but the real function is the support of industry and agriculture upon which civilization is dependent.

Jan 1, 1959

By Matthew J. Hrebar

Dragline stripping operations account for over one-half of the U.S. bituminous coal production mined by surface coal mining methods. The dragline is a popular stripping tool because of its flexibility in varying overburden depths and relatively low operating costs per cubic yard of overburden. Because of the relatively high capital costs of the machines and their use as a primary stripping tool, the selection process is an important step in the mine planning procedure.

Jan 1, 1979

By T. Gollaher

The use of paste thickeners for mineral tailings has gained increasing acceptance by the mining industry throughout the world and in the U.S. during the last five years. Advantages of water recovery and environmental sustainability are the driving forces for paste as an alternative to conventional thickening and the slurry pond. This paper presents a summary of the differences between paste and conventional tailings thickeners, along with recent examples of full-scale paste thickener installations.

Jan 1, 2010