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By Salvatore Fancello, Ferruccio Cribari, Amerigo Tanzi, Mauro D’Angelo, Massimo Lodico, Alessandro Bertero, Eliano Romani, Tommaso Gondolini, Fabio Giannelli

"The new metro line “C” entails the construction and rehabilitation of 24 stations and 21,5 km of metro line, 13 of which carried out underground; the new metro line will improve the transportation system of a congested city such as Rome.The new line “C” of San Giovanni metro station will be constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and will underpass the existing station. The underpass project envisages an Artificial Ground Freezing in order to excavate two new tunnels, while keeping trains running in the safest possible condition.In order to allow trains to regularly run to and from the existing station’s line “A”, a temporary structure for rail support, during excavation of the under-crossing tunnels, was installed and a real-time monitoring system was devised in order to control both soil temperature during freezing activities and the existing station’s behavior. The monitoring system has been one of the key to the success of the project.The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).THE NEW “C” LINE OF ROME’S METROThe world’s most complex and extraordinary Metro System is currently being built in the heart of Rome. Its underground route stretches underneath the most important monuments, churches and historical buildings.Rome’s Metro Line C is the longest urban underground railway in Italy and it is the first line in Rome to extend further east to the Great Ring Road, thus bridging the gap between the farthest suburbs and the Historical Centre. It is an original project, carried out mostly underground at a depth of 25/30 metres below road level."

Jan 1, 2016

By M. E. Gershon

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon’s pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon’s pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (157. ) of Professor Gershon’s pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 12, 1987

By E. Cho

Illinois No. 6 coals of IBC 101 and IBC 112 were treated in solution with sodium hypochlorite to remove their sulfur contents, especially organic sulfur. The lab experiments were conducted in two steps of leaching at room temperature and hydrolysis at 90oC. The removal of organic sulfur from IBC 101 was by 37.8% while that from IBC 112 was only 13.7% under their respective optimum conditions. This large difference in organic sulfur removal is considered to be due to difference in concentration of surface total acid group, 3.14 vs. 0.88 mmol/g of coal.

Jan 1, 2007

By S. A. Montague

In spite of the many new insulating materials, both synthetic and manufactured, that have been put on the market since the end of World War II, and notwithstanding the many millions of dollars applied to the development of synthetic mica, natural block mica1 is still a most indispensable insulator in various electronic components. It will remain so, barring some spectacular break-through in research that might provide a substitute fully acceptable as a replacement for mica in all of its superior properties. But this is not to say the future for mica is assured, or free from serious problems. Technological advances have created problems requiring a solution to be found if future requirements are to be filled.

Jan 1, 1962

By Steve Kral

In recent years, junior mining companies, mostly listed in Canada, have taken a beating in the finance markets. Simply put, potential investors have been leery of sinking millions into exploration and mining projects due to volatile commodities prices and an uncertain regulatory climate in developed and developing countries. The 2014 edition of the Prospectors and Developers Association of Canada (PDAC), however, seemed to be a bit different for some juniors. Equity valuations have improved and metals prices appear to be stabilizing. So, for some of the stronger junior companies, there is some hope. Merger and acquisition (M&A) activity is picking up and, believe it or not, companies are raising some capital. Billed as the largest annual mining meeting in North America, the PDAC conference attracted more than 25,000 mining and exploration professionals from around the world. Organizers were anticipating attendance to break the 30,000 mark. But, given the state of the exploration end of the mining business, 25,000 is still a respectable number. Junior companies that are in the project feasibility stage, or have made promising discoveries that stand a good chance of proceeding to production, are being looked at by potential investors. Those are the survivors of the last three years of dismal M&A activity. On the other side are the juniors that are still around ? and there are plenty of juniors that were at the PDAC last year but have since disappeared ? but have little or no working capital. One analyst calculated that there are about 850 companies with less than $200,000 in working capital and about 600 with negative working capital. This will likely result in fewer junior mining and exploration companies as the year progresses but the ones that remain should be stronger.

By Timothy O’Rourke, Karrie Buxton, Chris Lynagh, Daniel Dobbels, Frederick Vincent

The Doan Valley Storage Tunnel Project in Cleveland Ohio was constructed to control Combined Sewer Overflows (CSOs). It is a complex system of three tunnels ranging from 8.5 to 18 feet in diameter with a total length of about 2.3 miles that was put into operation in mid-2021. The project lies within and below the cultural, educational, and medical hub of Cleveland, which presented unique design and construction challenges. This paper provides a case history of the design and construction, with particular attention given to lessons learned in devising a large tunnel system that can carry both dry and wet weather flows constructed in rock with limited cover, within a flood plain area and vibrant urban center

Dec 1, 2022

By F. S. Knoll

Electrostatic separation is one of the most misunderstood physical processes used to beneficiate minerals. Nonetheless, millions of tons of titanium ores, iron ores and other minerals are processed every year economically, efficiently and safely. Over the past ten years major advances in electrostatic separation and its application have occurred. New processes include dewatering clay slurries, separating halite and sylvite, and shape separation of vermiculite and gangue minerals. Electrostatic separation techniques are based on one of two methods, electrophoresis or dieleccrophoresis -- processes involving charged and uncharged particles respectively. In some cases, the combination of these two techniques has proven quite useful. The purpose of this paper is to provide a basic understanding of the physical processes collectively called "electro- static separation" in order to enhance one's ability to define and consider new possibilities in mineral processing and other fields.

Jan 1, 1984

By C. L. Lin

A PC image-based on-line coarse particle size analyzer has been developed to measure particle size distributions under plant situations where overlapped particles are being transported on a moving belt conveyor. Although previous testing had shown satisfactory performance of this image-based system for separated particle size measurements (the non-overlapped case), it was necessary to modify original algorithms in order to solve the overlap problem and make the system suitable for plant operations. On-site testing has been conducted at a large copper concentrator in the southwestern U.S. for further investigation of the overlap problem.

Jan 1, 1995

By Fred C. Bond

The perennial subject of comminution is deserving of a fresh approach if one can be found. This is attempted here by directing attention primarily to principles rather than to theories. While theories attempt to explain how a certain process acts, principles delineate the laws which the action-must follow. Comminution may be defined as the progressive separation of particulate matter. At the present time this is accomplished commercially by applying energy in the form of compressive and, shearing forces. Such forces strain and distort the particles they contact. When-the applied stress locally exceeds the breaking strength at the weakest flaw in the particle, a crack tip forms. The surrounding strain energy flows to the crack tip, which rapidly extends through the particle as a break. The minute changes in shape and the resulting energy flow cause the failure of other highly stressed flaws, with the consequent formation of a progeny (1) of new smaller particles out of its destroyed progenitor. The applied mechanical energy is transformed into strain energy as the particle is distorted, and then into heat when it fails. Only a tiny fraction of the order of 1/1000 of the applied energy necessary for breakage appears as new surface energy in the product particles. The comminution problem is the relationship between, energy input and product particle size. Its solution is of great-economic importance,

Jan 1, 1961

By R. R. Guzman

In this study, the "Mine Project Risk Management" methodology, MPRM (Botin et al. 2011), has been applied to characterize the sources of uncertainty and to quantify risk in the mining engineering stages of Block Caving mining method. As the result, rock mass caveability and ore fragmentation were identified as the two most relevant parameters of this process and a methodological model has been developed to quantify the risk associated to each of these two parameters. Furthermore, the applicability of the proposed model has been validated using as a case study the Chuquicamata Underground Mine Project in Chile.

Feb 23, 2014

By R. L. Grayson

Focusing on relationships between severity measure versus productivity and other factors, this paper presents a comprehensive study of injuries for U.S. underground coal mines in 1996 by mine size. Based on analyses of data, generally the larger the mine, the more productive it is (in tons per employee-hour), but the more severe is its injury experience (r = 0.65). Within very large, large, and medium mine sizes, however, the more productive the mine, the less severe is its injury experience (r =-0.43, -0.36, and -0.26, respectively). For small and very small mines, a more deeply nested analysis is required to understand relationships. Other interesting relationships and comparisons are presented.

Jan 1, 2000

By John C. Kleiber

From time to time since the initial installation of an experimental flotation section in 1940 (reference A), Permanente Cement Company has made efforts to beneficiate the low-grade limestone fraction which occurs in its deposit at Permanente, California, The encouraging results outlined in this paper are the result of Permanente's latest effort. This paper discusses the factors governing the selection of the flowsheet with particular reference to marketability of the sand tailing by-product. The process flow is outlined in detail, and operating statistics of the plant are presented. Finally, the problems encountered in the operation of Permanente's beneficiation plant are discussed as well as solutions sought and found.

Jan 1, 1964

By A. L. Anderson, J. T. Rybock

Lime, soda ash and similar precipitants have been the industry standard for treatment of acid rock drainage (ARD) because of their proven ability and low per-gallon operational cost. However, these methods carry serious environmental drawbacks and high life-cycle costs. KEECO’s Silica Micro Encapsulation (SME) technology has all the positive characteristics of conventional ARD-treatment systems but none of the drawbacks. SME achieves highly effective treatment in a single step, provides options for ARD prevention and recovery of metals, requires lower capital expenditures, generates smaller volumes of higher-density sludge, consistently passes leach tests, and eliminates long-term liabilities associated with potential metal remobilization and hazardous waste landfilling.

Jan 1, 2000

By Dermot M. Winters, Brent T. Wahlquist, C. Y. Chen

The enactment of the Surface Mining Control and Reclamation Act (SMCRA) in August 1977 addressed subsidence resulting from underground mines, in addition to creating the requirements for reclamation of surface coal mines. Subsidence control regulations pursuant to SMCRA were initially promulgated in March 1979. Several revisions have since been made. In addition, due to court challenges some regulations have been remanded and others are still on appeal. In the meantime the Secretary has agreed to initiate rulemaking on some issues. It is yet to be determined how the prohibition of certain areas from surface coal mining operations under Section 522(e) of the Act applies to subsidence. This presentation discusses the status of the regulations and issues related to or affecting the subsidence regulations.

Jan 1, 1986

"The profile of the respondents was that of a professional responsible for communications, community relations or corporate social responsibility programs. By targeting a consistent professional profile it was possible to ensure that most respondents had a similar degree of responsibility and/or decision-making ability related to the application of communication technologies. The research attempted to be inclusive and attention was paid to interview respondents from both genders and from indigenous groups.4, 5 A codebook of 80 themes was developed that highlighted recurring topics; for example, codes were created to identify risks, benefits, policies and learning process of using social media and included topics that were repeatedly emphasized by respondents (i.e. age, efficiency and language). Both manifest coding (i.e. coding of the visible content, such as specific words) and latent coding (i.e. coding of underlying meanings) was undertaken (Creswell [13]). The codes were used in the qualitative analysis using ATLAS.ti software and network views were created to illustrate the relationship between major themes of this research. There are limitations to this research, largely related to the changing nature of the Internet and communication technologies. There is also a geographic limitation to the application of this research because most of the data was gathered primarily from Canadian sources.6 Different levels of Internet penetration, or limited access to computers or mobile devices, and low literacy rates may reduce the applicability of the research in countries with low Internet penetration. A more systematic process to selecting candidates may have helped bring balance to the final list of interview respondents. For example, most of the corporate respondents were from medium and large companies and there was not adequate representation of small mineral exploration companies. The research did not probe into social media applications by different business groups within the mining sector, such as smelting and processing."

Jan 1, 2011

By Richard Collins

The projected depletion and the increasing costs of petroleum and natural gas along with the public and governmental resistance to nuclear energy have caused coal to emerge as one of today's answers to both our short term and long term energy needs in power generation. In order to satisfy this need, major increases in coal production are mandatory, thus requiring more and higher capacity coal transfer terminals. The logic for selecting coal as the major fuel for power generation is based on many different reports on the existing and potential energy sources, which include petroleum, natural gas, hydropower, solar, geothermal, and nuclear. The following is a brief synopsis of these reports for each type of energy.

Jan 1, 1978

By R. Lawrence

Mineral property valuations to be used for Canadian securities regulatory purposes must comply with CIMVal1. The technical basis for a CIMVal report is the same as that required for a technical report that complies with NI 43-1012. NI 43-101 describes the content to be covered in a technical report, while also covering other requirements, one of which is that the report should be based on a property visit. CIMVal is based on five tenets that the valuator must follow: ? Materiality. ? Independence. ? Transparency. ? Competence. ? Reasonableness. Upon its adoption by CIM Council in 2003, it was hoped that the new CIMVal code would be adopted without change by the several Canadian regulators.

Jan 1, 2011

By Miguel Angel Banuet Rodriquez, Hector Conceso Aragon

"Construction of the longest road tunnel in Mexico is part of Acapulco’s alternate roadway to the scenic roadway project. This article provides a brief summary regarding details of the construction since the project began. Work was done by skilled engineers and Mexican workers that includes outstanding execution of the work in an urban and tourist area. This project will have a strong impact on the steady development of the port of Acapulco.Project locationAcapulco’s Alternate Roadway Project is currently under construction in the city of Acapulco, located in the Guerrero state of Mexico. It is an 8-km (5-mile) long roadway that starts at the Icacos neighborhood, heading toward Acapulco’s airport, crossing a drill-and-blast tunnel that is 3,160 m (10,350 ft) long under Veladero Park, a mountainous area. The tunnel overburden reaches a depth of 380 m (1,250 ft) approximately at the central point of the horizontal alignment, and continues with a 4-km (2.5-mile) long elevated road to connect to the existing Viaducto Diamante toll road (Fig. 1).Tunnel construction has already been finished using two portals for drilling and blasting operations; Brisamar Portal on the west side and Cayaco Portal on the east side (Fig. 2).Geometric dataOnly two main excavation cross-sections were considered in the executive design. The first one corresponds to the running tunnel for a three-lane vehicle section, with crosssection areas between 120 and 130 m2 (1,290 and 1,400 sq ft) taking into consideration different geological and geotechnical conditions to be encountered (Fig. 3).The second one corresponds to eight emergency bays, each one 50 m (164 ft) long, laid down within the tunnel outline, located at 400 m (1,312 ft) from each one with excavation cross-sections between 156 to 169 m2 (1,680 to 1,820 sq ft), in accordance to geological and geotechnical conditions to be encountered (Fig. 4).The tunnel’s horizontal alignment is completely straight, having a small curve within the vertical alignment on Cayaco portal, because there were some differences in levels when tunnel excavation started. Tunnel slopes were designed in such a way that rainwater does not run down into the tunnel at any time."

Jan 3, 2018

By B. W. Lawrence

Shaft alignment requirements are consistently met using conventional shaft sinking methods. Little attention has been given to achieving similar alignment accuracies using rotary drilled shaft methods. Alignment of these shafts is difficult to control and guarantee. Bare shafts and shafts that use drum hoisting systems can accept some deviation. However, combining drilled shafts with Koepe hoist installations presents new accuracy requirements for drilled shafts. This paper describes the importance of verticality with practical examples, and discusses various methods of measuring verticality and their respective limitations.

Jan 1, 1989

By Michael F. Gleason

In 1986, Gold Fields began negotiations with a large Nevada electrical power utility to supply power for its Chimney Creek Mine In northern Nevada. After the long negotiations reached an impass over various costs associated with the power line, a decision was made by Gold Fields to generate its own power. Self-generation is not uncommon overseas, but it is rare for any but very large or very small operations in the United States. Surprisingly, under certain conditions a mine can generate its own power profitably and Gold Fields has found that the associated operating and maintenance problems are minimal. The following report details what factors went into this decision and how it works. Hopefully, it can serve as a guideline for those who may find themselves in a similar position.

Jan 1, 1990