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By G. Barbery

In Mineral Processing, the objective of most processes is the separation of mixtures of minerals, which are originally associated in composite particles. Feed preparation processes grinding for instance, which take place before beneficiation or separation processes do not usually break particles at the boundary between mineral phases. They produce composite ("middlings") as well as liberated particle. It is therefore necessary, in a particulate system, to determine the proportion of particles which are liberated as well as, ideally, the size distribution of minerals which remain associated in composite particles. Up to now, there has been a lack of experimental techniques to characterize completely composite particulate systems. Heavy liquid separation which is commonly used to obtain information of this type can only be applied to simple binary cases for which one mineral has a low density (lower than e.g 2.8 ). The technique which is proposed in this paper involves the measurement of parameters on polished sections of particles mounted in a matrix, and the use of mathematical transformations to reconstruct in three-dimensions the information obtained from these measurements .

Jan 1, 1977

By Devan Naik, Matthew Stokes, Andy Nigro

This paper describes the surgical removal of a 24 ft dia. Slurry Shield TBM entombed beneath one of the country’s busiest commuter rail interlockings, the Harold Interlocking in Queens, NY, and the construction of the interface to a cut/cover tunnel which extended the mined tunnel section. A sophisticated SOE was built around the TBM to support active track loads within 8ft. of the excavation. Once the TBM head and guts were removed, a full round CIP lining was installed connecting the existing precast tunnel liner to the C/C tunnel under construction. All this construction was done on a narrow island of land without road access nestled between 7 mainline LIRR/Amtrak rail lines.

Jun 13, 2021

By Sadatoshi Ohmori, Karen Shinoda, Nobuharu Isago

Method of tunnel excavation is generally classified such as full-face excavation, bench-cut excavation, diaphragm with center pillar excavation, center drift advancing excavation and so on. These excavation methods should be selected properly in terms of ground condition, the area of tunnel section, the arrangement of construction. Center drift advancing excavation method in mountain tunnel construction, is often applied under quite weak ground condition, prior to the main tunnel widening excavation. Recently, the advancing drift is for the excavation of extreme larger section in main tunnel to confirm the stability of face. In addition, we make advancing deformation occur in drift when the construction was done in poor ground like squeezing and swelling ground, and the force occurred in main tunnel was expected to reduce by the effect of ‘dodging’ for support structure. Mechanical relation between drift and main tunnel has been mainly grasped on past experiences in Japan. However, the characteristic of tunnel enlargement was partially discussed by using the three dimensional analysis and the result was grasped by past experiences on the basis of each tunnel construction. It is considered that the natural ground stress is normally released as the advance displacement, but it was released after the main tunnel widening, causing a displacement and deformation increase. Up to now, the construction practice has shown the reduced displacement during the main tunnel widening excavation by the drift, and the numerical analysis agreed with above observation. However, there is no report found that the displacement and deformation at the time of widening excavation of the main tunnel become larger in case of a drift application. In Kyusyu area, western part of Japan, the northern part of Yoshinomoto tunnel was applied an advancing bench-cutting method for a center drift for the purpose of obtaining the geological information for support selection of the main tunnel in widening excavation. The shape of center drift was a perfect circle with a diameter of 4.0 m or 6.0 m and the same temporary support regardless of the geological situation. As a result, the displacement and deformation of the main tunnel after widening excavation were larger than the section where the center drift was not applied. Furthermore, the displacement and deformation of the main tunnel after its widening excavation was considered larger in the section where the cross-section of the center drift with 4.0 m diameter was applied than one with 6.0 m. Therefore, the center drift with a high rigidity support structure had the effect of suppressing the advancing deformation prior to the main tunnel widening excavation.

Jun 13, 2021

By Jerry C. Tien

The rare earth elements (REEs) are a group of 17 chemical (metallic) elements which appear in the periodic table. The group consists of 15 lanthanide elements along with yttrium and scandium (Table 1). They share many similar properties, which is why they occur together in geological deposits. Although commonly referred to as rare, they are really quite common; the reason they are perceived as rare is because it is not common to find them in commercially viable concentrations. These metals are critical to advanced technology, ranging from smart phones to global positions system (GPS) receivers, medical devices and jet engines. They are critical in green, high-tech and defense industries (Fig.1 and 2). Although there have been increasing efforts to find alternative supplies, these efforts have been complicated by the pollution that rare earth mining and processing creates. To extract rare earths minerals from mined ore is a complicated and costly process. The ore is first mined through normal mining process, the bastnaesite, which generally contains a number of minerals of little value, is first removed through a floatation process. The bastnaesite containing the REEs is further separated into their respective pure forms in a separation plant using acid and various solvent extraction separation steps. Each element has its own unique extraction steps and chemical processes. At times, these elements, in the form of oxides, will require reprocessing to achieve ideal purity. The last steps would be to further process into metals first, then alloys for various applications. The entire process takes approximately 10 days. The mining and processing of REEs, if not carefully controlled, can create environmental hazards. This is one of the reasons the Mountain Pass Mine in California was closed down in the 1980s.

Dec 1, 2013

By John J. Simmons

Federal and state regulations, in an effort to reduce acid rain, are becoming increasing more stringent regarding sulfur content of fossil fuels. Whereas coal from Illinois and Ohio contains between 1.5 and 37. sulfur, Wyoming has billions of tons of coal reserves containing less than O.5/% sulfur. However, much of Wyoming's coal is high in moisture, 25-30%, and low in energy, 8,200 to 8,900 BTU, vs. 10,500+ BTU for Illinois and Ohio Basin coals. Wyoming currently ships in excess of 130 million tons of coal to utilities as distant as Michigan, Wisconsin, Minnesota, Iowa, Nebraska, Louisiana, Oklahoma, and Texas. With freight charges ranging from $12.00-$20.00/ton, more than $1.5 billion a year is spent to transport water. A test shipment of more than 50,000 tons of Wyoming coal has recently been made from Mobil's Cabello Rojo Mine, south of Gillette, by Burlington Northern to the Robert's Bank British Columbia coal terminal for transloading and shipment to Taiwan Power Company. This coal assayed approximately 8,400 BTU/lb. and 277. moisture. Carbontec Energy Corporation feels the future availability of dried coal containing 11,000+ BTU could substantially enhance the potential export as well as the domestic market for Wyoming coal. Large and small utilities, along with industrial furnaces require tens of millions of tons of Wyoming, West Virginia, and other Eastern The federal government is encouraging the expenditure of hundreds of million of dollars by utilities to retrofit their boilers to allow them to burn higher sulfur coal. This program, if carried to completion, would cost many tens of billions of dollars, with the net result being high power costs sustained by the utilities. These costs will be passed on and paid for by the American consumer. A sensible alternative would be the burning of low sulfur coal by the utilities, without costly capital and operating expenditures. Carbontec Energy feels the successful operation of a Carbondry Coal Drying Plant in Wyoming will be the forerunner to other similar and larger operations in the State. CARBONTEC RESEARCH The activities of Carbontec's personnel to develop a viable process to dry sub-bituminous and lignite coal goes back some 14 years; in fact, for some of us it goes back to 1962 when we were involved in a program under which lignite coal from Truax Trayer's Velva mine was placed in low sulfur coal, which are burned alone or blended with high sulfur, Midwestern coal. Carbontec believes that a high BTU. reasonably priced, shippable coal fuel produced in Wyoming and delivered at costs competitive with Eastern low sulfur coal, could offer substantial benefits to Wyoming coal producers, utility customers, and to the State of Wyoming.

Jan 1, 1989

By K. P. Wang, Ta M. Li

The Chinese energy and mineral industries are readying themselves for a period of dynamic transition, unprecedented in the country's long and sometimes turbulent history. The transition comes as a result of the government's new program of "Four Modernizations" in its agricultural, defense, industry, and science and technology sectors. The announced program is generally considered by Western observers to be a moderate, pragmatic approach to get China on the road to industrial parity with Western nations by the year 2000. The game plan calls for integration with the West to beef up Chinese know-how and the purchase of foreign technology to supplement areas where China lacks the ability to do so itself. While the role of energy and minerals is not specifically mentioned in the program, it was made clear to ME that China realizes the basis of any sustained modernization program is tied closely to the health of its minerals sector. Various published reports have indicated the existence of an already vibrant energy and minerals sector with world rank production in coal, iron ore, tin, antimony, cement, pyrite, asbestos and tungsten to name just a few. For the most part, except for the export metals, the primary focus of China's production has been on fulfilling domestic needs. Now the new initiatives are aimed not only at self-sufficiency, but also on propelling the country's natural resource clout into international prominence. With a mineral resource base that is considered by many westerners a potential bonanza, China's new long march toward modernization will be an exciting adventure, well worth watching. Big Projects Spark Excitement China's renewed commitment to a more liberal program is as much a desire to "walk on its own two legs" as it is a backlash from the frustrating years that followed the Cultural Revolution of the 1960s and early 1970s. Much of the early excitement was initiated by China's Premier and Party Chairman Hua Guo-feng in speaking to the fifth National People's Congress (NPC) in 1978. Here, Chairman Hua presented the Communist Party's 10-year blueprint for economic development. Specifically, the Party's plans called for completion of 120 large-scale industrial projects by 1985. Mentioned were 10 new iron and steel works, 30 power plants, six new railways, 10 oil and gas fields, nine nonferrous metal

Jan 3, 1980

By X. P. Zheng, H. K. Lin

Barium fluorophlogopites were synthesized in the laboratory to investigate the effects of composition and crystal parameters on surface properties and floatability. The negative surface charge of mica is determined by the barium content, the crystal cell volume, the distance between the layer structure and the Ba-O bond length. The higher the barium content, the larger the cell volume and distance between the layer structure, and the longer the Ba-0 bond, the more negatively charged the surface is, and, hence, the more easily adsorbed are cationic collectors. When an anionic collector (sodium oleate) is used, barium oleate forms on the mica surface and hence chemical adsorption occurs.

Jan 1, 1995

By Michael Rehbock-Sander, Romed Insam

"INTRODUCTIONThe idea of building a summit tunnel under the Brenner occurred to the Italian engineer Giovanni Qualizza as far back as 1847. But it was to be another 160 years to pass before a base tunnel was to be built.In 1971 the idea of a tunnel at the Brenner was dusted off again. The UIC, the International Union of Railways, commissioned a study for a new Brenner railway with a base tunnel. By 1989 three feasibility studies had been drawn up which formed the basis for further planning of the Brenner Base Tunnel.This was the start of the planning activities. In 1994, the European Union included the Berlin-Naples corridor in the list of priority projects. Ten years later, Austria and Italy signed a State Treaty to build the Brenner Base Tunnel. In that same year, what is today the BBT SE was established.PROJECT DESCRIPTIONThe Brenner Base Tunnel (BBT) with a length of 55 km is the centrepiece of the Helsinki-Valletta Transeuropean Traffic Corridor from Finland to Southern Italy. The BBT tunnel system connects in the north with the Innsbruck station (Austria) as well as to the feeder routes in the Lower Inn Valley, and opens to the south with the projected new line in the direction of Verona (Italy). The tangible design efforts have been underway since 1999; the start of construction of the first section was in the year 2007. The project is financed by the Italian and Austrian governments (each 30 %), as well as by the European Union (40 %).From 2027 onwards the Brenner base tunnel, including the existing lines connected with it, will carry a daily average of 330 trains (approx. 80% cargo trains and 20% passenger trains)."

Jan 1, 2016

By Angelina Anani, Nathalie Risso, Carlos Olmos de Aguilera

The traditional approach to safety clearance monitoring and proper PPE usage in underground mines is time-consuming, costly, and susceptible to negligence. However, automated real-time monitoring can be implemented using computer vision-based approaches. This study aims to develop a system that provides timely information based on the automatic detection of proper PPE use and safety clearance in underground mines. Deep learning and a decentralized computing structure between the cloud and sensing devices (fog technology) are used. We hypothesize that a camera-based system can provide near real-time assessment of proper PPE use and verified clearance to access restricted areas in underground mines.

Jun 25, 2023

By Francisco J. Sotillo

Using new ecological-natural-organic depressant for gangue and pyrite with antibacterial properties (control of acid mine drainage) with new improved xanthate collectors using rheology additive not chemical reacting with xanthate resulted in better sulfide flotation. Rougher-scavenger lead flotation tests were conducted increasing the concentrate grade from 7.07% Pb to 13.44% Pb, enhancing selectivity. Lead recovery increased from 64.08% to 79.38% and 80.40% using only the new depressant, and improved xanthate Z-11 and Z-4, respectively. The results demonstrated that the new depressant was selective and efficient, and the new improved xanthates stronger more selective collectors.

Feb 22, 2026

By A. R. Biggart, A. Walters, G. J. E. Kramer

The Owner Procurement Process or OPP is a proven, viable alternative contract delivery method that is potentially applicable to many tunnel projects. Using the OPP, the owner specifies and procures major tunnel construction items such as tunnel boring machines and tunnel linings and provides them to a tunnel excavation contractor in order to manage risk and accelerate project schedule. However, due to industry perceptions regarding potential owner risk, it is seldom considered or is rejected out of hand. In fact, past performance demonstrates that the process significantly minimizes owner, contractor and over-all project risk and mitigates the impact of any claims and differing site conditions. The paper outlines how the process should be structured to achieve schedule, cost, quality and risk management benefits. Potential and perceived disadvantages are discussed and how the process can be structured to mitigate or avoid them. The planned implementation of this process on the tunnels for the Silicon Valley Rapid Transit Project in San Jose, California is discussed.

Jan 1, 2005

By John H. Wright

The United States Antarctic Program (USAP), through its principal support contractor Raytheon Polar Services Co. (RPSC), has recently completed a three-year project comprising nearly 936 m (3,071 ft) of undersnow utility tunnels at Amundsen-Scott Station, South Pole, Antarctica. The tunnel serves the new station facilities that are currently under construction. It houses the piping that conveys fresh water from current and future water well sites, as well as waste water to repositories in abandoned wells. The undersnow tunnels permit year-round access for system operations and maintenance. The network of tunnels is entirely unlined and unsupported. And, for the most part, it maintains a rectangular cross section of 1.8-m-wide x 3-m-high (6 x 10 ft).The tunnel runs from 6 to 14 m (18 to 45 ft) below the surface. Eight 1-m- (3.3-ft-) diam raises bored from the surface serve the network as emergency escapeways.

Jan 1, 2002

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By Michael V. Mergentime, Prakash M. Donde

The Nutley Quarry Trunk Sewer Project is a good example of a tunnel that went through difficult and complex ground. The 2 m (7ft.) diameter and 840 m (2,750 ft.)long tunnel passed through soft ground, mixed face, and hard sandstone. The soft ground and mixed face tunneling provided several challenges. During excavation of the tunnel, the Contractor encountered a number of unanticipated large boulders. In addition, the length of the mixed face portion of the tunnel increased by 100%. The Contractor tried various construction techniques to overcome the difficult ground conditions and complete the project. The tunneling progress was slower than expected. The Contractor claimed extra costs for differing site conditions. Through discussions and negotiations between the Contractor, Engineer, and Owner, all of the changed condition claims were settled before the construction of the project was completed. This paper addresses the difficult ground conditions, claims evaluation, and how they were resolved by cooperative efforts between the Contractor and the Owner/Engineer.

Jan 1, 2001

By Håkan Stille, Jalaeddin Y. Rafi, Fredrik Johansson

"INTRODUCTIONIn tunneling projects, pre-grouting is performed with the purpose of establishing an impervious zone around the tunnel periphery. This is obtained by reducing the penetrability of the most conductive fractures in the rock mass. The main attention, besides economy of the project, is given to limiting the ingress of water into the tunnel to a certain amount during construction s well as operation period. Failure in pre-grouting process may, according to Bruce (2007), significantly affect the project in terms of safety, performance, cost and time. In this respect, determination of design parameters (pumping pressure, properties of the mix and stop criteria) affects these projects significantly. In current practices, depends on the geological conditions and requirements of the project these parameters differ widely. Weaver (1991) recommends selection of design parameters, specifically grout injection pressures, based on site specific factors and the conditions at each specific hole into which grout is to be injected (grout hole logging and water pressure test data). Houlsby (1990) correlated the allowable grouting pressure to the quality of the rock mass and the rock cover above the grouted fracture. In his methodology, grouting should be continued until the maximum pressure was attained. Later, Lombardi and Deere (1993) introduced the Grout Intensity Number (GIN), which limits the combination of injection pressure and injected grout volume in order to control the energy induced in the fracture i.e. avoid fracture jacking. Even though the GIN method was a step forward in understanding of the mechanism of the fracture deformation, there are ambiguities connected to this methodology, thus determination of the intensity number is challenging (see e.g., Rafi and Stille 2015)a.A main problem when no theoretical solution is practiced is that effects from the chosen injection pressure, such as possible increases of transmissivity and changes in total grouting time, remains hidden in the overall grouting process. The question is if a high or a low pressure should be used to fulfil the requirements of the projects at the lowest possible cost."

Jan 1, 2016

By G. H. Harris

The flotation behavior of two high sulfur coals using a non-ionic surfactant as collector from two series of compounds containing oxygenated functional groups was studied in detail using a 2-liter Denver flotation cell. The performance of these reagents was compared with that of an oily collector, namely dodecane. The results showed that at the same coal recovery, a much lower dosage of these non-ionic surfactants was required as compared with that of dodecane. More import was the performance of these compounds as promoters for oxidized as well as un oxidized coal. Mechanisms of interaction of these compounds with the coal are suggested.

Jan 1, 1993

By S. Anderson

Advances in inexpensive computer automation led to the development and utilization of a computerized ore control system at Cyprus Coppers tone Gold Mine near Parker, Arizona. These new ore control practices improved accuracy, performance, and productivity of the ore control effort. An automated system for data collection, including bar coding of blast hole samples, laboratory analysis, data management, grade estimation, cut delineation, and ore zone stakeout, plays a major role in ore control practices. This is of particular interest because of the large amount of blast hole information being processed, analyzed, and reported daily.

Jan 1, 1991

Spirals have become one of the most popular methods for treating fine coal. Unfortunately, spirals tend to produce an undesirably high specific gravity cut-point and often misplace significant amounts of coal and/or rock. In the present study, a process-engineering tool known as linear circuit analysis was used to identify problems with traditional spiral circuits and to suggest alternative configurations. These analyses indicate that a modified rougher-cleaner circuit incorporating a middlings recycle stream offers the best option for improving performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing preparation plant. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce cut-point and improve separation efficiency. Preliminary economic analyses show that the new circuit provides an attractive payback on the capital investment.

Jan 1, 1998

By S. S. Peng

In this paper, the precise definitions for a number of commonly used subsidence parameters are given. The subsidence parameters have been determined using an integrated approach for 110 subsidence cases collected in the major US coal fields. Attempts have been made to establish empirical formulae for the parameters. The results of this study indicate that some traditionally-held concepts should be changed.

Jan 1, 1995

By T. D. Arnold

The Barrick Bullfrog underground mine was established as an afterthought to the main open pit. As open pit ore dwindles, the underground mining becomes increasingly more important as an ore source, and to the overall economics of the project. This situation is similar to many other mines, and there is a strong move towards underground mining in the United States today. There are inherent problems in starting and operating underground mines in the shadow of any open pit operation, and at the Bullfrog there were several attempts at productive increases that were both successful and unsuccessful.

Jan 1, 1996