Search Documents

By Y. Wang, E. Forssberg, A. Johansson, B. Chan

A super-conducting high gradient magnetic separator with matrix vibration in dry separation mode is a powder purification device, which has been used to remove weakly magnetic impure particles from fine calcite powders below 53 µm in this study. A fundamental question concerned is the evolution of the matrix clogging under gas-solids loads. This paper presents the improvement of the separation selectivity using a method of mechanically based vibration on the matrix in the separator. The functions of the matrix vibration are discussed. The results indicated that the mechanically based vibration on the matrix within a high intensity magnetic field while a feed was introduced in an air stream, was found to be effective for the dry purification of fine powder materials.

Jan 1, 2001

By I. Tsolas

This paper presents the use of non-parametric approach (i.e., data envelopment analysis, DEA) for the development of environmental sustainability indicators in mineral processing using environmental, economic and/or integrated indicators (i.e., indicators that interrelate two dimensions of sustainability). A case study based on real publicly available data is presented to illustrate how the proposed approach can be implemented in practice. The merit of this approach, which is based on the productive efficiency framework, is that it provides environmental sustainability indicators that can be used internally for benchmarking purposes and externally for sustainability reporting.

Jan 1, 2008

This study was conducted to establish the effects of a diesel particulate filter (DPF) system with sintered metal substrate on the concentrations and size distributions of nano and ultrafine aerosols and concentrations of nitric oxides in underground mine air. The study focused on the formation and transformation of nucleation mode particles in mine air under prevailing test conditions. Experimental work was conducted in the NIOSH Diesel Laboratory at the Lake Lynn Laboratory experimental mine, a facility developed to allow evaluation of control technologies directly in underground conditions. The DPF system was examined for four repeatable steady-state engine modes using a naturally aspirated mechanically controlled Isuzu C240 diesel engine fueled with ultralow sulfur fuel. The engine coupled to an eddy-current dynamometer was operated in the underground drift with tightly controlled ventilation. Measurements upwind and downwind of the exhaust system discharge were used to quantify the effects of the DPF system on the mine air. A baseline was established using a standard muffler. The study showed that sintered metal DPF systems reduced the total mass of aerosols in the mine air by more than ten-fold when compared to a muffler. The nucleation mode aerosols (50dem<40 nm) in mine air were found to be strongly influenced by engine operating mode. The concentration of nucleation mode aerosols was found to be significantly higher for high-load modes than for low-load modes. The muffler and DPF system resulted in comparable total nitrogen oxides (NOx) concentrations. However, the nitrogen dioxide (NO2) fraction of the total NOx was found to be substantially higher for both systems for low-load modes than for high-load modes.

Jan 1, 2009

By Yves St-Amour, Vince Luongo

This paper will discuss one of the largest construction projects the City of Portland has undertaken. This phase of the Willamette River Combined Sewer Overflow (CSO)project consists of approximately 18,500 ft of tunnel in soft ground, requiring the construction of six deep shafts and jet grout ground improvement. The purpose of the project is to reduce volume of combined sewerage overflows from the drainage areas on the west side of the Willamette River. Bencor-Petrifond-Pacchiosi Joint Venture was awarded a contract to design and construct six deep circular shafts, jet grout ground improvement for three bridges and jet grout ground improvement break-in/outs for some shafts. Of the six shafts the Pumping Station Shaft was the deepest and largest, requiring a permanent ground support system with a deep jet grout ground water cut-off to 335-ft deep. The joint venture used state of the art methods and equipment to achieve its objectives and build the structures through some very difficult alluvial soils to great depths next to the Willamette River. The paper will provide a general discussion of the shaft construction and jet grout ground improvement installed for this phase of the project. It will also discuss some of the technical challenges encountered while effectively managing risk and costs, resulting in a successful project completed in a timely manner.

Jan 1, 2005

By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012

By G. Balletto, C. Furcas

"The mineral raw materials industry is a key-component of the Gross Domestic Product of industrialised economies, closely related to both the building and the industrial sectors. Despite this, at local level mining and quarrying are associated with both irreversible environmental damage and several visual alterations affecting the natural landscape. In this sense, SIA (Social Impact Assessment) has become a strategic tool that can not only improve the prediction but also the assessment of the social impact by involving the local communities in a participatory process. Taking into account the SIA experience, together with the examination of some relevant international case studies, it is possible to draw up a list of good practices for mining project management, from exploration through to closure and beyond, with quarry restoration. Such good practices will complement the existing studies, focusing on environmental issues, with the social issues arisen considered in SIA application."

Jan 1, 2011

By T. Hudaverdi

Several studies have been conducted on blastability and prediction of fragmentation. The term blastability is used to refer the susceptibility of the rock to blasting and is closely related to fragmentation. Parameters that determine fragmentation by blasting may be divided into two groups. The first group consists of blasting design parameters. The blast design parameters are controllable parameters and determined by the explosive engineers. The burden, spacing between holes, bench height, drillhole diameter, stemming height and explosive density are all design parameters. The second group consists of rock mass parameters that are referred to as uncontrollable parameters. The uncontrollable parameters are physical and mechanical properties of rock and rock mass structure. The strength, modulus of elasticity, density of rock, number of joint sets, joint orientation and joint spacing are among uncontrollable parameters. The rock mass parameters and blast design parameters should be considered together to explain fragmentation process. In this study, a blast database was accumulated to use for multivariate analysis. The blast database contains the blasts performed near Istanbul region quarries and the blasts that were preformed in various mines in the world by the blasting researchers. The cluster analysis was used to separate the blast data into different similarity groups. Group memberships were analyzed and checked by the discriminant analysis. Then, the multivariate regression analysis was used to develop a prediction equation for blast fragmentation for each group. Finally, a validation of the suggested models was performed for various mines. The model comprises blast design parameters, mechanical properties of rock and rock mass structure.

Jan 1, 2011

By Manuel Arnáiz, Pedro R. Sola, Rogelio Baudot, Manuel Herrera, Carlos S. Oteo

The aim of this paper is to describe and analyze the ground treatment performed between January and May 2002 in order to increase safety during excavation and reduce instability problems along 180 m of tunnel, during the construction works associated with line 10 extension to the Madrid Metro. The tunnel was excavated using the traditional Madrid Method and in the section considered in this paper layers of sand were detected around the tunnel crown area with a significant presence of water, the in?ow of which needed to be controlled with a minimum impact on the surrounding environment.

Jan 1, 2003

By Michael R. King

The application and use of steel fibre reinforced concrete in precast tunnel lining design is a growing trend due to its advantages in performance over plain concrete, and ease of manufacture compared to traditionally reinforced concrete. However, the design process and performance characteristics of the material are poorly served by current codes and standards. This paper provides some basic design guidance for segmental linings, and compares the material properties for the different material options. A typical example is considered to compare the possible results of lining arrangement and thicknesses for a plain, reinforced, and fibre reinforced design solution.

Jan 1, 2005

By D. Tao, R. Honakey, B. K. Parekh

The dewatering of stable phosphatic clay suspensions generated from phosphate beneficiation in the central Florida is an issue of practical and theoretical importance. Because of its tiny particle size and surface charge, the phosphatic clay takes up to 20-30 years to settle in water and causes environmental, aesthetic, economic, and handling problems. An efficient and cost-effective dewatering/consolidation process for phosphatic clay is of great interest to the phosphate industry in Florida. In this paper, the consolidation and dewatering behavior of phosphatic clay was studied by use of anionic flocculants with and without sand addition. The effects of pH, initial polymer concentration, polymer dosage, polymer addition steps, and metal cations (K+, Ca2+, and Al3+) on the flocculation of phosphatic clay have been studied. Experimental results indicated that clay suspensions were well flocculated at pH 10.5 by DPW-1-1355 and Magnafloc 5250 flocculants acquired from Ciba Specialty Chemicals. Sand particles from phosphate flotation added to the clay slurry promoted flocculation and increased clay consolidation. K+ showed good performance to improve the flocculation characteristics by neutralizing clay surface charge. The adsorption mechanisms of flocculants on clay particles were also discussed in this paper.

Jan 1, 2006

By L. L. Lacerda, A. J. Blair

The Wolf Creek Upper Narrows Tunnel (Upper Narrows Tunnel) is one of the first major highway tunnel in the United States implementing the use of spray-on membrane for purposes of constructing a double-shell drainage solution between an initial shotcrete lining and a final cast-in-place concrete lining (Figure 1). In the case of the Upper Narrows Tunnel the primary membrane is constructed with a spray-on product manufactured by Degussa, namely Masterseal® 340 FA (MS 340) that has been utilized previously in other tunnel projects. Shotcrete-like in application, but differing in physical properties, MS 340 is now outdated, and is succeeded by Masterseal® 345 (MS 345), a nearly identical product, with improvements in material properties. Tunnel project histories utilizing either MS 340 or MS 345 are discussed and summarized with regard to the respective motives for prompting spray-on membrane selection and the realized benefits resulting from spray-on membrane construction. With an emphasis on the Upper Narrows Tunnel, project summaries discuss details of the aspects of design for spray-on membrane construction methodology as opposed to conventional sheet membrane construction methodologies. It is anticipated that experience gained during the construction of the Upper Narrows Tunnel with respect to other tunnel projects that have utilized spray-on membrane will be of use for future tunnels employing spray-on membrane in drainage solutions.

Jan 1, 2005

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

Coal has been mined in the central Appalachian coalfields of southern West Virginia, western Virginia, and eastern Kentucky for more than a century. The dwindling reserve base consists in large part of coal that would have been considered unmineable by earlier generations. Nearly every current operation is working on a property where coal has been extracted in the past, from seams either above, below, or both. NIOSH is conducting research aimed at helping mine planners prevent hazardous conditions due to multiple seam interactions. To-date, more than 300 case histories have been collected from underground mines, mainly from central Appalachia. This paper focuses on several of the more challenging situations that have been encountered, including: • Room-and-pillar development 20 ft (6 m) beneath full extraction workings at a depth of 1,000 ft (300m) of cover (Virginia) • Pillar recovery 45 ft above full extraction workings at 900 ft (270 m) of cover (Virginia) • Near-simultaneous room-and-pillar mining with pillar recovery with 40 ft (12 m) of interburden and 1,500-2,000 ft (450-600 m) of cover (Kentucky) • Longwall mining directly beneath main entries in overlying seams (West Virginia) • Some of these operations have been highly successful in overcoming the challenges, others less so. The lessons learned from their experience will help ensure that these and similar difficult reserves can be mined safely.

Jan 1, 2006

According to the previous research, it is found that the thickness of cover is mostly less than 100 m for highwall mining system. However, for most of the Chinese surface coal mines, the mining depth is over 150 m; on the other hand, the shovel-truck is the most common mining technology. As a result, a lot of residual coal will be remained around end-walls. Considering these facts, the calculated methodology of highwall mining system under thick cover is presented in this paper. Meanwhile, numerical simulation of highwall mining system under thick cover was carried out. The outcome shows that the calculated methodology for pillar stability of highwall mining system under thick cover presented in this paper is acceptable. In other words, the highwall mining system is feasible to extract the residual coal around end-walls in Chinese surface coal mines. Thus, not only coal recovery ratio can be improved, but also can increase the production life of surface coal mines in China.

Jan 1, 2012

By J. B. Hadaway

The current limit to power transmission for grinding mills through one mill pinion is approximately 7,500kW. Above this power rating either twin pinion arrangements or Gearless drives are required. The SMTP concept was developed to overcome this limitation by using two pinions with a single large drive motor. The SMTP mill drive offers major advantages in capital cost and greatly simplifies plant layouts, while using an innovative adaptation of industry-proven single helical gearing. Through the use of a single motor, provision of variable speed drive is greatly simplified. The SMTP can also be used for significant power upgrades on existing mills.

Jan 1, 2001

By C. R. Copeland

Airborne dust emission standards are receiving growing attention. This trend is motivated by significant health studies that have shown adverse health effects due to exposure to dust. Currently, the air quality standards are not specific to particles in the nanoparticulate range (<1,000 nm). However, as our understanding of health related matters increases, it is very likely that nanoparticulate standards will be adopted. It was previously believed that typical comminution and material-handling practices could not result in airborne nanoparticulates. However, experimental studies using air monitoring and SEM have verified the presence of nanoparticulates in the air as a result of comminution and material handling. This means that emerging nanoparticulate air quality standards are a real possibility for industrial operations. With this emerging problem facing the minerals industry, effective suppression methods for nanoparticulates should be explored. Systematic studies have indicated that nanoparticulates from silica can be suppressed utilizing hygroscopic reagents such as calcium chloride. This reagent was as much as 93% more effective than water in suppressing silica nanoparticulates.

Jan 1, 2007

By K. Grubaugh

Ghana’s physiographic and geologic features are the basis for its long mining history. The Gold Coast colony has been a significant producer of gold. The gold of the Akan forest (Ghana) was a terminus for caravans that plied Saharan trade routes. Now it also produces significant quantities of manganese, bauxite, and diamonds In addition, the country produces kaolinite, silica for glass, salt, and both aggregate and dimensioned stone. Most secondary minerals are consumed locally but some amounts do find international markets. Ghana revised the mining laws and regulations in 1986. These revised laws dramatically increased gold production and improved the country’s economy. The success of these laws spawned imitators in other African states such as Cote d’Ivoire, Mali, and Burkina Faso. Representatives of these countries claim Ghana was their model. Environmental regulations exist but an intensive adversarial atmosphere is lacking. Ghana has also offered the mining industry incentives like accelerated depreciation rates and exemption from import duties on related supplies and capital equipment. The country has also pursued an aggressive policy to restore the nation’s business infrastructure.

Jan 1, 2001

By M. S. Klima, A. P. Pinkerton

Solid-bowl (decanter) centrifuges are used extensively to dewater slurries in a wide range of industries. However, the application of decanters as classification devices is not as common. In this study, the performance of a continuous, pilot-scale, solid-bowl centrifuge was evaluated when classifying an ultrafine coal slurry containing nearly 60% material less than 10µm. The current study examined the effects of operating conditions on centrifuge performance. The test conditions included centrifuge bowl and scroll speeds, volumetric feed rates, solids concentration, and pond depth. Centrifuge performance was evaluated using partition curves, along with product yields and solids concentrations.

Jan 1, 2000

By Russell Miller, Fun-Den Wang

High Pressure Water Jet Assisted Tunneling The high pressure water jet assisted tunneling project was conducted in a granite quarry near Skykomish, Washington, approximately 90 miles east of Seattle. A 7-ft diam tunnel boring machine was modified and equipped with high pressure water jets. The concept that tunneling rates can be improved by using high pressure water jets was validated, with an average increased advance rate of 50% to 60%. For some tests, the advance rate was more than doubled. A comprehensive economic analysis has shown that very significant savings are possible. At a 50% increase in advance rate, cost savings of 14% and 24% were projected for 10-ft and 20-ft diam tunnels respectively. These benefits were seen to be relatively insensitive to water jet equipment costs.

Jan 1, 1976

By M. Schlegel, J. A. Villa Mena, R. E. Vivas

ArcelorMittal, headquartered in Luxembourg, is one of the world’s largest steel and mining companies. It supplies steel to industries such as automotive, construction, and energy, with a strong emphasis on sustainability and innovation. The company employs about 125,000 people and, in 2024, produced 42.4 million tons of iron ore and 57.9 million tons of crude steel across 15 countries. Its mining operations span Canada, the United States, Mexico, Brazil, Ukraine, Bosnia and Herzegovina, Kazakhstan, and Liberia, focusing on iron ore and coal extraction to support steel production. This study examines Peña Colorada, one of Mexico’s largest iron ore mines (a joint venture by ArcelorMittal and Ternium). Facing declining ore grades, Peña Colorada adopted Hexagon solutions to uncover and capture project value. A comparison of two Life of Mine (LOM) plans from 2012 and 2016 (before and after implementing Hexagon solutions) shows that between 2019 and 2023, Peña Colorada reduced actual waste by 26% (compared to 2012 LOM) and 19% (compared to 2016 LOM). LOM Plans are generated yearly, and each time, opportunities for reducing mining waste were identified, evaluated and implemented. The key driver was schedule optimization using Hexagon MinePlan Schedule Optimizer (MPSO). This reduction means less waste transported to disposal sites, resulting in fewer hauling equipment operating hours, lower fuel consumption, and reduced carbon emissions.

Feb 22, 2026