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By C. J. Roos

Ground-engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these "consumable" items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corp. to predict the consumption of excavator teeth at a particular mine site. This paper presents the results of the Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2010

By Yuchen Wu, Jing Mei, GUOZHONG LIU, KE GAO, Songjie Tian, Jianwei Cheng, Yu Wang, Yuhang Wu, Hui Wang

The stability and integrity of protective coal pillars between the longwall working face and development roadways are greatly affected by the mining activities such as the development face advancing or retreat mining. Due to underground strata pressure, the coal pillar cracks could be further developed and then the air leakage passages (mainly cracks) could be produced greatly. The air circulation caused by the atmospheric pressure difference between the two sides of the coal pillar may also provide suitable conditions for the possible spontaneous combustion of the residual coal in the mine gob. In this paper, a typical the protective coal pillar in a Chinese coal mine is studied. The deformation and stress of coal pillars during the mining process of longwall working face are simulated by using FLAC3D. The displacement and strain of coal pillars are analyzed. Two indexes, the linear fracture rate (LFR) and area fracture rate (AFR), are introduced to characterize the development of internal cracks’ development within coal pillars. By using field measurement, the air leakage intensity distribution due to coal pillar cracks is obtained; the equation of air leakage resistance of coal pillar under the influence of mining is derived. Then, the possible location of large air leakage of coal pillar is determined, which can be used as guidelines to study the possibilities of coal spontaneous combustions happening in pillar or mine gob. The research results help to control such potential hazards in advance.

Jun 16, 2022

By Laura Suarez, Jörgen Kajberg, Pär Jonsén

In recent years, slag, a residue from pyrometallurgical processes, has become more attractive in circular economy frameworks to increase the efficient use of resources throughout the life cycle of steel products and help in the reduction of carbon emissions. Its applicability is strongly dependent on the particle size, and therefore, the optimization of breaking processes should be approached by increasing the knowledge of the dynamics of slag to promote fracture. Increasing the knowledge on themechanical response ofmanganese slag opens up the potential for the development of cost-effective numerical models, e.g., constitutive models based on inverse engineering calibration frameworks or digital twins. In this study, rate-dependent tests of manganese slag have been performed using a split Hopkinson pressure bar device for testing its dynamic mechanical response. In order to obtain information about the crack initiation and fracture process, 2D ultra-high speed imaging was implemented with a sampling frequency of 663,200 fps for diametrically loaded specimens. Full-field deformation measurements using digital image correlation (DIC) techniques showed a staggered fracture process where failure points on mechanical response curves vary due to the internal events happening in the material. Localized frictional occurrences and inertial effects acting inside the pre-cracked matrix have a strong effect on the global mechanical response, and therefore, a great variability of strengths was obtained.

Nov 3, 2023

By Edwin W. Tooker

Creation of needed new resources will be accomplished mainly by imaginative and diligent geologic exploration because geologic availability is the key determinant of future mineral supply. Adequate resources of most commodities can be made available for the rest of this century and beyond if they are discovered. Thus conversion of hypothetical and speculative resources into available reserves will provide the principal challenge to earth scientists. Additional problems now compete for our attention. First is a challenge to discover more resources than have been found to date for domestic needs as world-wide demands increase exponentially and as easily found high-grade deposits are rapidly being depleted. New ways to find new types of deposits are required. Second, the United States, a resource importer, increasingly is challenged for access to foreign supplies through stiffening competition and economic or expropriation sanctions. Balancing needs for mineral supply and environmental protection is a third challenge. Geologic explorers must consider statutory as well as economic and technologic requirements, controlled access to public and private lands, competition with urban sprawl or wilderness, limitations on discovery, appraisal and mining methods, and restoration of mined areas. Finally, is the challenge to temper public and private attitudes and assure that decisions bearing on resource problems are based on comprehensive credible facts. While striving to maintain and improve the standard of living, many Americans appear to disdain and mistrust those organizations that provide their material where-withal. Meeting these challenges effectively, and in time, will require careful appraisal of the resource system and the joint efforts of industry, university, and government earth science research.

Jan 1, 1974

By Brianna M. Eiter, Jennica L. Bellanca

Mineworkers face a challenging and dynamic work environment every workday. To maintain a safe workplace, mineworkers must be able to recognize worksite hazards while they perform their jobs. Though hazard recognition is a critical skill, recent research from the National Institute for Occupational Safety and Health (NIOSH) indicates that mineworkers fail to identify a significant number of hazards. To further the understanding of mineworkers’ hazard recognition ability and to begin to address hazard recognition performance, NIOSH researchers analyzed data collected during a laboratory research study to determine the effect of individual mineworker factors including risk attitude, work experience, and safety training on hazard recognition accuracy. The results of this study show that mineworker risk attitude and safety-specific work experience affect hazard recognition performance while hazard-specific safety training does not. These results suggest that some of these individual factors can be overcome through experience and training. Potential strategies that can be used to address these factors are also discussed.

Aug 31, 2020

By S. A. Sanderson

The last two decades have witnessed the resurgence in popularity of a century old tool for shaping laws and public policy – the ballot initiative. In recent years, anti-mining special interests have used the initiative process to secure voter approval of measures to ban modern surface mining for gold and silver. In November 1998, voters in Montana approved such a measure1 – the effects of which have been devastating to the mining industry in that state. In November 1999, anti-mining groups sought to place a nearly identical provision on the general election ballot in Colorado. They did not succeed, but the battle over mining’s future continues in the most important forum of all – the court of public opinion. The Colorado measure failed, in large part, because its proponents failed to convey a positive environmental theme. The mining industry also exercised early-on the rights available under state law for administrative and judicial review of the initiative, instead of relying upon the limited relief that would have been available had it waited until after the secretary of state approved the measure for the November election ballot. This article will summarize the ballot initiative process in Colorado and the proceedings that took place over Initiative No. 215.

Jan 1, 2001

By Yushuai Xian, Youjun Tao, Fangyuan Ma

This study compared particle size distribution and density distribution of crushed products for waste printed circuit boards (WPCBs) before and after heat treatment. The crushing process for heat-treated WPCBs is a selective crushing process; more metal is concentrated in the coarse particle range of 1.0–0.5 mm and high density range of 2.8–2.96 g/cm3. WPCBs were separated using the Falcon separator to recycle useful metals. The Box-Behnken module of Design-Expert was used to obtain optimal separation parameters, namely, rotational frequency of 25 Hz, recoil water pressure of 0.025 Mpa and feed speed of 34 ml/s. On this basis, the separation indexes for WPCBs with and without heat treatment were compared. Experimental results show that the recovery effect is better for heat-treatedWPCBs than for thosewithout heat treatment. Comparedwith the non-heattreatedWPCBs, the product grade of heat-treated WPCBs is 1.95% higher, and its recovery is improved by about 14%. Finally, characteristics ofWPCBs before and after heat treatment were analyzed on the basis of stress experiments and scanning electron microscopy (SEM), respectively. Results of mechanical characterization indicate that the stress experiment for non-heat-treated WPCBs has a maximumpressure load of 212 N and displacement of 20mm, but heat-treatedWPCBs only need 140 N stress and 14 mm displacement. SEM shows that copper foil and fiberglass cloth are deformed in different directions and sizes after heat treatment to form gaps, which promote liberation of copper foil and fiberglass cloth.

Sep 10, 2020

By Grover H. Emrich

Pennsylvania,, due to its location in the humid east, is fortunate to possess within its borders large quantities of water. Most of the State is drained by three major river systems-the Ohio, Susquehanna and Delaware. This abundant supply of surface water has been widely utilized throughout the State, but today other sources of water must be developed due to the increasing demands for water, die largest undeveloped source of water in Pennsylvania is ground water. Pennsylvania is also fortunate to possess extensive coal resources. These coal resources have contributed measurably to the development and prosperity of the States Coal and water's - two valuable resources - have been necessary for the development and industrialization of Pennsylvania, The State needs both resources but can no longer afford to develop one while adversely affecting or destroying the other, We are aware of the effect of coal mining on surface water, but coal mining can also materially affect subsurface water, This effect will according' to the local geologic conditions.

Jan 1, 1965

By Hans Adden, Anne Lehan, Markus Thewes

"1. INTRODUCTION AND MOTIVATION Traditionally design processes are focussed at creating new tunnels for lowest building cost. But the trend towards sustainable constructions in tunnelling has greatly increased in recent years. A critical subtask of this approach is to realize the potential for optimizing and reducing the life-cycle costs (LCC) of tunnels and their components. To evaluate underground infrastructure projects from an economic point of view is therefore a highly topical subject of public authorities as well as private companies participating in Public Private Partnerships (PPP) projects. Nowadays, in the case of public works contracts, the contracting authorities shall draw up rules not only for the design but also for life-cycle costing. Within the scope of the decision-making process of building a new tunnel, planning the maintenance activities or the refurbishment of a tunnel in operation, the decision-makers need detailed knowledge about the current and future financial conditions of the planned projects and selected sub-measures. But in practice, the initial costs still represent the primary decision criterion in the planning phase, whereas the subsequent or follow-up costs, respectively, are only estimated roughly. Although tunnels are the key components and the most costly parts of the transport infrastructure, only a small number of scientific papers deal explicitly with the calculation of life-cycle costs for underground infrastructure. And in these cases, most authors use as the starting point only the basic form of the Net Present Value method which is known as the frequently applied life-cycle costing technique in building construction. The present study explains the strategic concept of life-cycle costing and its fundamental instruments for operational implementation. It shows the necessity to take into consideration that there are fundamental methodical problems when the life-cycle concept is transposed without modifications from building construction to civil engineering. The paper will discuss in detail some selected associated problems with the net present value method. On the basis of operational and safety related tunnel equipment it is shown, what impact this may have on principle determining the LCC of tunnels. Selected best-practices of maintenance planning for tunnels undertaken by the German Ministry of Transport fill the theoretical approach of the concept with life and give a practical orientation. In particular government authorities but also construction companies are interested parties in modern cost management considerations. The reason for this development is the replacement of aged excisting structures and the advancement of technical standards. The increase in the total numbers of tunnels (Fig. 1) as well as the need for future re-investments in existing tunnels show the overall economic impact and justify the change towards the life-cycle perspective."

Jan 1, 2016

By Igor Gonzales G.

The Southern Peru Copper Corp. (SPCC) recently built an integrated copper project consisting of dump- and heap-leaching operations at its mine complex in Peru. The pregnant leach solution (PLS) containing the solubilized copper from the leaching operations is processed in a new solvent extraction/electrowinning (SX/EW) facility to produce high-purity cathode copper. The dump leaching and SX/EW facilities are located near the Toquepala mine site. The crushing and heap-leaching operation is located at the Cuajone Mine. The pregnant leach solution from Toquepala and Cuajone is pumped 35 km (22 miles) to the SX/EW plant at Toquepala. The SX/EW plant consists of three trains of solvent extraction (SX), a tank farm area and an electrowinning (EW) facility. The solvent extraction plant has a total PLS flow capacity of 3,210 m3/hr (113,360 cu ft/hr). The electrowinning facility has an expected long-term production capacity of 97 t/d(107 stpd) or about 35 kt/a (38,500 stpy) of cathode copper. However, present production exceeds the expected long-term by about 20%.

Jan 1, 1996

By J. Seiter, S. Cox, E. Kim

Mining has always been among the most hazardous of occupations, and with the increasing demand for coal and minerals, safety in mines assumes even greater importance. Worldwide, underground miners are being exposed to noise and respirable dust hazards associated with roof bolt drilling. These hazards are now being understood to cause irreparable damage to the health of miners. The objective of this research was to discover if a polycrystalline diamond compact (PDC) drill bit generates less respirable dust and hazardous noise than a competing tungsten carbide (WC) bit in dry vacuum drilling. In order to control the drill parameters the drilling tests were conducted in a laboratory setting. The results were obtained by determining the quantities of dust and noise generated using each drill bit and analyzing those levels, using monitoring devices and software to collect the data. This paper includes information on the experimental setup, equipment used, drilling parameters, and data collected. Our results indicate that PDC bits produce significantly less noise and dust than WC bits. Our findings can contribute to improving the working conditions of rock bolter operators by reducing noise and dust generation.

Jan 1, 2014

By Yunxing Cao, Xinsheng Zhang, Bingbing Meng, Shuaifang Guo, Li Wang, Junsheng Zhang

During the initial process of mining a longwall working face, it is often found that the roof will not collapse readily, which increases the risk of later roof collapse disasters. Explosive and hydraulic fracturing are common roof weakening techniques; however, they have certain limitations. In the present study, CO2 fracturing was used for roof weakening during the initial mining phase in the Changcun coal mine, China, which is a novel strategy. First, by analyzing the lithological characteristics of the working face and applying combined beam theory, the breaking spans of the top coal, immediate roof, and main roof were determined before weakening. An F-35 CO2 fracturing device with a rated pressure of 270 MPa was used, which provides fracturing energy equivalent to 0.968 kg of TNT. The fracture radius of the main roof was studied by ANSYS/ LS-DYNA combined with the hanging roof-breaking theory to determine the optimal layout of CO2 fracturing drills. The results show that the breaking spans of the top coal, immediate roof, and main roof were reduced by 3.99 m, 7.66 m, and 22.03 m, respectively. The main roof collapsed as the working face advanced, eliminating the chance of later roof collapse disasters. Compared with hydraulic fracturing and explosives, CO2 fracturing is safer and more practical, giving it significant application potential.

Nov 23, 2023

By D. Brady

When deciding to deploy rescue teams underground the decision makers need to be able to determine that there won?t be an explosion whilst the rescue teams are underground. Previously general body concentrations in areas likely to be travelled were compared to explosive limits on a one off basis with no formal process looking at trends or other areas. A new approach is being adopted that takes into account the rate of change of gas concentrations with triggers set to enable a withdrawal of personnel prior to a possible explosion and influences such a barometric pressure changes. This paper explains the rationale behind the changes made and the advantages and implications of adopting such an approach.

Jan 1, 2012

By Nikhil Dhawan, Amit Barnwal

The present study reports a processing route to recover metals from integrated circuits of discarded random access memory (RAM) units containing ~ 66% printed circuit boards and ~ 33% integrated circuits. The integrated circuits are manually separated, grounded, classified, and subjected to water fluidization for the effective separation of metals. The significant separation was achieved via water fluidization, and the underflow fraction was magnetically separated. The magnetic fraction was thermally exposed in a muffle furnace, and the process optimization was carried out using a Box-Behnken statistical design. The detailed characterization at subsequent steps significantly aids the understanding of metal-plastic separation and enrichment. A concentrate containing 97% metals (Fe-59%, Ni-9.5%, Cu-7.7%, Sn-13.4%, Pb-5.6%, Ag-1.6%) with 96 wt% recovery can be recovered from discarded IC units. The process pursued is simple, adaptable, and environment-friendly, and the product can be used in conventional smelters.

Jun 23, 2020

By A. K. Sinha

Modern mine ventilation systems have grown rapidly in recent years both in tern of its complexities as well as its value for human health and safety. Although computer models are now available to help the design and operation of mine ventilation systems, considerable differences often exist between the computer based predictions and practical results. Research conducted to compare computer result with practical measurements made in ventilation circuits simulated in a physical model seems to confirm such differences. It is concluded that although a mine ventilation computer model is a very powerful tool, it can be utilized to its full potential only after more reliable input data are developed.

Jan 1, 1985

By Michael E. Zellars

The distribution of phosphate in Pliocene-Miocene deposits of the Southeastern United States was controlled by the prevailing geologic setting. For each basin a unique set of conditions in terms of relationship of land mass to shelf, depositional environment and seawater composition, and movement controlled phosphate distribution. Concentration sufficient to recognize the deposits as a resource occurred in lagoons or shallow neritic zones, with clastics and carbonates diluting the section basinward. Each deposit within a basin displays similar metallurgy and lithology, notwithstanding post-depositional alteration.

Jan 1, 1978

By Zhibiao Guo, Jinglin You, Dongshan Yang, Yuanxin Zhao, Yuhui Li, Jingwei Gao

By utilizing collapsed gangue to create gob ribs, roof cutting and roadway maintenance (RCRM) technology enables coal pillar-free mining, presenting a novel approach. Due to their inherent structure, faults, which are common geological formations, can lead to various hazards, including fault sliding and significant deformation of roadways. In this study, a selfdesigned underground engineering simulation test device is utilized to imitate the cross-fault mining of the 11,101 working face in the Qipanjing Coal Mine (East). The objective is to examine the behavior of the surrounding rock and stress evolution. Generally, the experimental findings demonstrate that compared to the return air roadway, the RCRM roadway experiences a 3.3% decrease in maximum coal rib stress. This suggests that the implementation of this technique can effectively alleviate the stress on the surrounding rock of the roadway. The maximum coal rib stress, lateral pressure of the gob rib, and maximum deformation of the roof near the fault of the RCRM roadway are 11.3%, 25.6%, and 86.1% greater than those of the conventional geological conditions, respectively. The roadway deformation is negatively impacted by the fault structure. Based on experimental data and field measurements, a discrepancy in the maximum roof deformation between the test and field monitoring results under typical geological conditions is 8%. This indicates a favorable alignment between the test results and the real-life scenario. In conclusion, the proposed targeted control technique is implemented in the field by integrating the mining invariant equation and gangue volume expansion equation. This not only validates the effectiveness of the technology but also offers valuable insights for the future utilization of RCRM technology under comparable circumstances.

Feb 20, 2024

By Y. Nien Wang, Moe Amini, Heiner Sander, Max John

INTRODUCTION As the population increased along the coast route (California Route 1), and the people’s need to have guaranteed access increased, the landslides and related road closures began to have serious adverse economic impacts. Landslides were causing major long-term road closures about every 10 years on average. In 1983, ground movement at Devil’s Slide caused Highway 1 to be closed for an extended period of time which caused significant economic loss to the surrounding coastal communities. A number of options for bypassing the slide area were considered, and the Martini Creek inland bypass was selected for design. Subsequent litigation led to the creation of the Devil’s Slide Tunnel Study in 1996. The results of this study indicated that a tunnel alternative would be competitive with the inland bypass. The final decision was left to the citizens of San Mateo County, who approved the tunnel alternative in the November, 1996 election After completion of environmental studies and the processing of legal challenges, the final environmental document was finished in 2001. The preferred tunnel alternative was designated to proceed for final design and construction. PROJECT DESCRIPTION The Devil’s Slide Tunnels consists of a separated two-lane road, one lane in each direction, which passes through twin tunnels and over twin bridges and then connects with the existing non-separated, two-lane road at each end. The total length of the project is approximately 1900 meters consisting of four main project divisions, which are described below, going from south to north. 1.Operations and Maintenance Center (OMC) area, 2.Southern approach roadways to the South Portals (250 meters), including the South Rock Cut,

Jan 1, 2005

By Gerald H. Luttrell, Seyed Hassan Amini, Aaron Noble

One of the most important processing engineering tools for designing mineral processing facilities is linear circuit analysis. This technique, originally conceived and developed by Meloy, Williams, and Fuerstenau nearly four decades ago, provides fundamental insights regarding how unit operations interact and respond when arranged in multi-stage processing circuits. Researchers have successfully utilized this tool to improve the operating performance of industrial processing circuits incorporating coal spirals, magnetic separators, mineral spirals, and eddy current separators. More recently, advanced versions of this tool have also been developed to provide a standardized framework for circuit mass balance calculations, to output exact analytical solutions to mass yield and value-based efficiency expressions, and to estimate uncertainty propagation in separation circuits. This article reviews the historical development of linear circuit analysis, describes how the technique has evolved to address more complex circuit design problems, and presents industrial case studies that highlight the importance of this process engineering tool.

Two new inorganic-organic hybrid polymers, Al(OH)3-polyacrylamide (Al(OH)3-PAM) and Mg(OH)2-polyacrylamide (Mg(OH)2-PAM) were synthesized and successfully applied for the treatment of oil sand tailings. The results indicate that both Mg(OH)2-PAM and Al(OH)3-PAM were unaffected by the change in pH, and could be applied to oil sand tailings with varying sand-to-fine ratio (SFR). The optimum dosages for the Mg(OH)2-PAM and Al(OH)3-PAM were about 330 g/ton and 650 g/ton, respectively for SFR 3.75. The flocculated oil sand tailings dewater quickly producing 66-68% solids. The flocculated tailings produced similar filtration rate before and after shear. Mg(OH)2-PAM treated oil sand tailings produced twice the filtration rates (220 ml/min) compared with Al(OH)3-PAM. This study clearly indicates that Mg(OH)2-PAM and Al(OH)3-PAM is a viable solution while decreasing the mass-production of tailings and increasing the rate of water-recycle.

Jan 1, 2012