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By Mahmut Altiner

This study aimed to produce magnesium oxide (MgO) particles with different properties from dolomite ore using an experimental procedure comprising four stages: sample preparation (S1), HCl leaching (S2), precipitation (S3), and calcination (S4). Three different base sources (NaOH, KOH, and NH4OH) were used as precipitant in the third stage to obtain magnesium hydroxide [Mg(OH)2] from a leachate solution, which was obtained in the second stage. Next, Mg(OH)2 particles generated by different alkali sources were calcined at various temperatures from 600–1000 °C for different durations (1–5 h). The effect of these base types on the properties of each product was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), atomic force microscopy (AFM), and wet chemical analyses. The experimental results indicated that each product was identified as periclase (MgO) mineral, which was produced with a specific surface area (SSA) of 4.49–44.54 m2 /g depending on the production conditions. The surface roughness of the MgO particles increased with increasing calcination temperature. SEM analyses showed that MgO particles produced at a temperature of 600 or 800 °C were amorphous, indicating that the process was not influenced by the base type, but MgO crystals were smooth when the calcination temperature was 1000 °C. Finally, it was determined from all experimental findings that MgO particles produced via the addition of NaOH have superior properties (such as higher SSA and lower surface roughness) compared with MgO particles produced with KOH or NH4OH as the alkali source. These properties led to great improvement of its usability in industry.

By Mahmut Altiner

This study aimed to produce magnesium oxide (MgO) particles with different properties from dolomite ore using an experimental procedure comprising four stages: sample preparation (S1), HCl leaching (S2), precipitation (S3), and calcination (S4). Three different base sources (NaOH, KOH, and NH4OH) were used as precipitant in the third stage to obtain magnesium hydroxide [Mg(OH)2] from a leachate solution, which was obtained in the second stage. Next, Mg(OH)2 particles generated by different alkali sources were calcined at various temperatures from 600–1000 °C for different durations (1–5 h). The effect of these base types on the properties of each product was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), atomic force microscopy (AFM), and wet chemical analyses. The experimental results indicated that each product was identified as periclase (MgO) mineral, which was produced with a specific surface area (SSA) of 4.49–44.54 m2 /g depending on the production conditions. The surface roughness of the MgO particles increased with increasing calcination temperature. SEM analyses showed that MgO particles produced at a temperature of 600 or 800 °C were amorphous, indicating that the process was not influenced by the base type, but MgO crystals were smooth when the calcination temperature was 1000 °C. Finally, it was determined from all experimental findings that MgO particles produced via the addition of NaOH have superior properties (such as higher SSA and lower surface roughness) compared with MgO particles produced with KOH or NH4OH as the alkali source. These properties led to great improvement of its usability in industry.

By William Gleason

"The city of Denver, CO has experienced extreme growth in the past decade, with the population of the city topping more than 700,000 people in 2018. The current storm water drainage system was put in place in the early 1900s and has not been able to keep up with the growth of the city.When it rains north and east of the city, the runoff goes toward the South Platte River. With the dense population and sometimes severe thunderstorms in the summer, the city has experienced significant flooding that not only endangers lives of residents, but some of the storms have caused millions of dollars of property damage.The Platte to Park Hill Project is a $298-million nearterm, four-phase solution to the flooding that includes the Globeville landing outfall; an open drainage project in the Cole neighborhood in north Denver; an area for temporary water detention and another temporary water detention in Park Hill.The largest and most complex phase of the project is the Globeville landing outfall — a $70-million box culvert project that includes a pair of 157-m (515-ft) long, 243-cm (96-in.) diameter storm water tunnels that pass beneath a busy rail yard with 17 tracks for the Union Pacific Railroad (UPRR) and two Regional Transportation District (RTD) commuter rail tracks. The tunnels, which were installed parallel to a pair of existing 243-cm (96-in.) tunnels, were designed by Brierley & Associates as a client of Merrick & Company for the City & County of Denver, and Bradshaw Construction constructed the one-pass tunnels.From the start, it was evident that the tunneling portion of the project would be the most challenging because of the rail yards.“It’s a little bit more complicated because the railroads have such tight restrictions for settlement,” said Rebecca Brock, Brierley’s project manager. “We had a lot of meetings with Union Pacific and RTD to figure out what are prescribed versus tolerable settlements.”“The portion extending beyond the UPRR under the RTD rails was challenging, as RTD is new to tunnel installations under its tracks,” said Lester Bradshaw, president of Bradshaw Construction. “The RTD tracks employed a unique foundation of continuous concrete with integral raised concrete ties on rubber bushings. Minimizing settlement to these tracks was a critical requirement.”"

Jan 9, 2018

By Richard H. De Voto

The McDonald gold project and two satellite gold deposits near Lincoln, MT were discovered in the early 1990s. They contain at least 307.9 t (9.9 million oz) of gold and 933 t (30 million oz)of silver. The McDonald gold deposit alone contains 223.9 t (7.2 million oz) of gold reserves that can be open-pit mined and processed by cyanide heap leaching at a projected cash operating cost of $6.10/g ($190/oz). The deposit is predominantly oxidized with no chance of acid production. It can be mined, operated and reclaimed with minimal permanent environmental disturbance other than the creation of an open-pit filled with a fresh-water lake that would support trout.

Jan 1, 2000

By Roger Best

In the mining industry, where some of the vehicles are larger than a one-story house, tire maintenance cannot be accomplished by the tire shop alone. It takes an army of people to maintain a fleet of 100 trucks that may be transporting gold, iron ore, oil sand, copper or coal from an openpit to a refinery and eventually delivering the product to a customer. Everyone working in and around these mammoth machines has a duty to help with the maintenance of the tires, whether they know it or not. These responsibilities comprise observation and reporting hazards up to and including changing out a tire and recording the information in a tire-tracking program such as TreadStat.

Jan 2, 2010

By Botelho Junior, Amilton Barbosa, Denise C. R. Espinosa, David B. Dreisinger

Copper and cobalt can be found on nickel laterite ores, and cobalt can be found also on copper ores, and many contaminants such as iron, aluminum, and magnesium are associated with these ores. In hydrometallurgical process, a purification step is necessary after leaching due to the presence of these impurities. Chelating resins are more selective for some metals than others, making them more efficient than cationic resins. This overview discusses chelating resin applications to recover copper, nickel, and cobalt from mining process and mining tailings and the effect of contaminants in leach solution. Chelating resins with iminodiacetate functional group can be used for selective copper recovery, and both iminodiacetate and bis-picolylamine resins are highly selective for nickel and cobalt. Chelating resins with the same functional group can have different performances on the kinetics of loading, because of variations of structure, the density of functional group, and degree of cross-linking. This article reviews commercial chelating resins that can be applied in leach solutions with different compositions, and also possible innovations for uses of chelating resins to recover metals from mining process and mining tailings.

By A. Fuerst

The recent seismic events have shown that earthquakes have an immense destructive power. Chile was hit in February 2010 with a seismic intensity of 8.8 on the Richter scale, and had loss of about 700 killed persons, while Haiti was hit in January 2010 with 7.0 killing about 220?000 people. The event in Haiti showed that the seismic events can lead to a disaster if no preventive measures are taken. On the other side, the seismic event in Chile has hit a well-prepared country with moderate consequences. The earthquake with 6.6 Richter in Japan in March 2011, have further shown how severe the consequences can be if critical equipment is involved. Fortunately, the equipment in a mine has not the potential hazard as a nuclear power plant. Anyway, we are diligent and it is obvious that the seismic risk may lead to a real disaster even if the probability is small. The GMD is an important component in the grinding circuit of a mine. This paper maps out earthquake-prone areas including expected earthquake magnitude calculated according to relevant standards, focusing mainly on the building code IBC 2009. An overview is provided on how this standard is applied to mining equipment to minimize damage and aid large mills in operation to successfully withstand seismic effects. The differences in stresses and forces on the GMD and foundation are shown based on a turning and stopped mill simulation during an earthquake. The results demonstrate the need to maintain active and operating earthquake detection systems. Aside from detecting an earthquake?s magnitude, the sensor information can also be used to reduce the harmful effects that an earthquake has on mining equipment. As follows the earthquake requirements are defined. The last part of this paper explains how to fullfill these requirements.

Jan 1, 2012

By A. D. Davis, C. J. Webb, C. S. Johnson

The Belle Eldridge Mine is an inactive lead-zinc mine in Spruce Gulch south of Deadwood, South Dakota. Acidic mine drainage (AMD) produced at the site drains into Spruce Creek, a tributary of Whitewood Creek. The site is on U.S. Bureau of Land Management (BLM) property. Extensive fieldwork was done at the Belle Eldridge Mine through the cooperation of the BLM and the South Dakota School of Mines and Technology. The site was extensively mapped to identify physical and environmental hazards such as tailings, waste rock, collapsed buildings, adits and workings. An exhaustive search of the historical records of the Belle Eldridge Mine was conducted. Maps of the under-ground workings of the Belle Eldridge dating from the 1930’s and 1940’s were found. The maps were used to correlate currently collapsed features to old adits and tunnels. Using hand corers and a portable drill rig, waste rock, tailings and soil core samples were collected and depth to bedrock was determined and the total volume of waste and tailings pile were determined. Related work examined the hydrology of the site. The site is very complex hydrogeologically. Numerous underground and surface workings and tunnels add to the complexity. Several seeps are located at the site, one of which is producing AMD. Recharge to the site was studied, and a 100-year flood plain map was produced.

Jan 1, 2000

By Gerald C. Smith

Introduction Newmont Mining Corp.'s Carlin Gold Mining Co. mines gold ore and waste material from four open-pit mines in Northeastern Nevada. Combined production rate is 24.5 Mt/a (27 million stpy). The company is producing gold bullion from the 2.4 kt/d (2600 stpd) Carlin Mill No. 1. and the 2.3 kt/d (2600 stpd) Maggie Creek heap leaching plant. In August 1985, the 6.3 kt/d (7000 stpd) Carlin Mill No. 2 at Gold Quarry came on-line. The total combined throughput of 11.2 kt/d (12,000 stpd) will make Carlin Gold Mining one of the largest US gold producers. Feasibility studies are underway to increase the total gold out-put from Gold Quarry. This will be done by adding a continuous dump-leaching process that will recover gold from lower grade ore. History In 1961, Newmont exploration geologists located claims in the Lynn Creek mining district near Carlin, NV. An exploration drilling program revealed significant gold mineralization. A stepped-up drilling program revealed an ore body with an estimated 10 Mt (11 million st) of ore containing 109 t (3.5 million oz) of gold. Test results in 1963 allowed metallurgists to develop the flowsheet and design for a 1.8-kt/d (2000-stpd) countercurrent decantation (CCD) cyanide plant. Carlin Gold Mining Co. was formed to operate the property. Carlin purchased its first mining equipment in 1965. This consisted of two Bucyrus-Erie 2.7 m3 (3.5 cu yd) shovels and nine 27.2 t (30 st) Wabco Haulpak trucks, two Inger¬soll-Rand track-mounted drills, one Chicago Pneumatic T-650 rotary drill, one rubber tired Michigan 280 dozer, one Caterpillar D-8 36A track dozer, one Caterpillar 16 motor grader, and the necessary ancillary equipment. The fleet was capable of mining 3.2 Mt/a (3.5 mil¬lion stpy) working two eight-hour shifts, five days a week. In 1967, one P&H 1500 3.8 m3(5 cu yd) diesel electrical shovel and three 59 t (65 st) Dart trucks were added to the fleet, along with a Chicago Pneumatic rubber tire mounted rotary drill. This equipment addition increased the mining capabilities to 5.7 Mt/a (6.3 million stpy). Three separate pits, the Main, East, and West, within a 1.6-km (1-mile) radius of the Carlin mill were being mined. The crew consisted of 46 hourly men and three supervisors. This equals 497 t/ total hourly manshift (548 st) or 407 t/total manshift (515 st). Rising gold prices in the early 1970s allowed lower grade deposits to be mined at greater distances from the mill. The Boot-strap pit, 19.3 km (12 miles) north of Carlin, was started in 1973. Two Hough 45.4 t (50 st) front-end loaders, four Wabco Haulpak 45.4 t (50 st) trucks, and a second track type D-8H dozer were added. The higher grade ore was trucked to the Carlin mill using three

Jan 11, 1985

By Derek J. Penrice

A critical element of the Transbay Transit Center Program, the Caltrain Downtown Extension (DTX) will extend commuter rail service into downtown San Francisco and accommodate future statewide high-speed rail service. The DTX project includes 1.8 miles of underground construction, comprising significant sections of mined and cut-and-cover tunnel. At the request of stakeholders, an updated cost estimate was prepared early in the project?s preliminary engineering phase. Unsurprisingly, this yielded a cost substantially higher than the available budget. This paper provides a summary of the management processes and planning decisions taken to bring the project back to budget, resulting in a configuration which derives maximum value from available funding and retains maximum flexibility for future system expansion.

Jan 1, 2008

Application of microprocessors, programmable logic devices, and other computer-oriented hardware and software on-board large surface mining equipment to optimize availability and productivity, stretch machine life, and protect against catastrophic breakdown has been a goal of heavy-equipment manufacturers for several years. Progress in this direction has not been as rapid as many manufacturers anticipated in the mid-1980s, and, on the other side of the coin, mining industry and machine operator acceptance of such products has not always been enthusiastic. However, the trend toward such development seems undeniable. Large surface mining equipment in the future will doubtless carry more, and not fewer, applications of computers and computer-related products. The intensity of development interest and degree of progress in commercializing such on-board computer and computer-related products on surface mining equipment varies considerably among the manufacturers. Summarized here are the on-board computer-oriented products of three heavy-equipment suppliers-P&H Harnishfeger, Marathon LeTourneau, and Haulpak not a comprehensive survey, but, perhaps indicative of the direction such development is taking.

Jan 1, 1990

By S. Borner Schweizer

An overview over SAM’s approach to assess corporate sustainability performance illustrates how sustainability challenges are linked to trends, assessment criteria and finally company performance. This process is exemplified with some general and industry specific criteria. Lastly, results of the Dow Jones Sustainability Assessment 2004 show a considerable gap between leading and average companies. Best practice examples demonstrate how lagging companies could improve their sustainability performance.

Jan 1, 2005

By Brian Garrod

Increasing use of pressurized-face tunnel boring machines in North America has produced a similar increase in the application of precast concrete tunnel linings. Where a pressurized TBM is needed, immediate ground support and ground water pressure resistance is also required. A segmental lining installed within the TBM tail shield provides the only available means of providing such a sealed lining. This paper addresses new developments in North America in lining applications and design. For the purposes of this paper, a precast concrete tunnel lining is defined as a tunnel lining constructed using precast concrete segments that are assembled into a lining ring. The lining rings are connected adjacent to each other to form a tunnel lining. Each segment has a sealing gasket around it so that when the lining is completed, it provides a fully waterproof lining system. The ring is erected within the tail shield of the TBM and the annular gap around the ring is filled with grout as the machine moves forward. The ring is not expanded and normally provides the finished lining of the tunnel with no requirement for a second pass lining. The TBM has a series of hydraulic rams that push on the leading edge of the segmental lining to provide the sole system of forward propulsion for the machine. The rings are tapered, being longer on one side than the other. This allows the rings to be installed either on a curve or in a straight line depending on the rotational position of the rings.

Jan 1, 2008

Minerals are fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels?mining, processing and manufacturing finished products. The estimated growth rate for the real GDP of the United States was 2.1 percent and the nominal GDP was about $13.8 trillion in 2007 (Table 1). The prime interest rate decreased to 7.25 percent in December from 8.25 percent at the beginning of 2007, reflecting actions taken by the Federal Reserve Board to counter financial difficulties surrounding subprime mort-gages. Delinquencies on subprime mortgages increased throughout the year, affecting not only the delinquent home owners but also financial instruments invested in mortgage-backed securities. The average contract mortgage rate for the purchase of previously occupied homes in the United States was 6.35 percent in November; a slight decrease from 6.37 percent in January but still greater than 5.34 percent reported in July 2003, the lowest rate in the past five years. With the tightening of credit, the seasonally adjusted annualized rate for new privately owned housing starts declined 27 percent from December 2006 to November 2007. The loss in the residential market was balanced by a 9-percent increase in nonresidential construction between January and August 2007, during which slight increases occurred in nearly all

Jan 1, 2008

By Brian Fulcher, Michael Bell, Shimi Tzobery, Werner Burger, John Bednarski

The Arrowhead Tunnels Project represents the final portion of a 70 km (44-mile) long water conveyance facility that will bring up to 28 m3/sec (1,000 ft3/sec) of water into Southern California. The 13 km (8-mile) tunneling project is well underway and consists of two, 5.8 m (19-foot) diameter TBM bores through extremely variable geological conditions. The tunnels lie near the base of the San Bernardino Mountains and several significant faults including the San Andreas Fault run within one kilometer (0.6 miles) of the tunnel alignment. Numerous other significant faults cross the tunnel alignment and water pressures in the tunnel have been recorded as high as 20 bar (300 psi). This paper describes some of the problems and challenges encountered and the solutions implemented to advance the two hybrid TBMs under conditions that ranged from hard rock with no water inflows to full-face granular material under 10-bar pressure and in excess of 32 l/sec (500 gpm) inflows. Due to the range and severity of ground and water conditions actually encountered, the Owner-Contractor-Designer team eventually found that adjusting the means and methods to be more responsive—virtually on a day-by-day basis—was needed to suit the conditions

Jan 1, 2007

By A. J. S. Spearing, A. Mueller

The support of intersections in coal mines remains an important safety issue, mainly because the large diagonal span compromises the stability of the roof. This structural weakness is further exacerbated if the intersection is developed incorrectly, the pillar corners fail or the crosscuts are angled (not perpendicular). This report details the current support systems used and investigates unplanned falls of ground in intersections in coal mines throughout the United States. A possible failure mechanism is proposed and some suggestions are made to improve the effectiveness of the support in these vital areas.

Jan 1, 2009

By O. Ofor

Coal fines of less than 0.5 mm particle size, discarded as too fine for gravity separation, were subjected to flotation tests at varying pH and temperatures using modified dosages of kerosene as oil phase and methylisobutylketone (MIBK) as frother. Optimal coal recovery of over 74% was obtained using 200 kg kerosene and 4 kg MIBK per ton of coal fines at a pH of 9.7 and an ambient temperature of 26° C. The coal concentrate obtained under these optimal recovery conditions assayed 9.10% ash, 0.35% sulfur and 0.011% phosphorus, representing reductions in the ash, sulfur and phosphorus contents of approximately 75%, 43% and 8.3%, respectively. Its gross calorific value was 32.9 MJ/kg, its percentage of volatile matter measured 30.6 and the fixed carbon content was 66.3% (d.a.f). Caking tests showed the optimal concentrate has a standard welling number of 1 and is a Gray-King coke type C. These results show that the optimal flotation product could be utilized for such industrial purposes as steam raising or for processing in gasworks, but it would be unsuitable for metallurgical coke production.

Jan 1, 1993

By T. Karalis

Perlite is a generic term for naturally occurring siliceous rock. It is a form of natural volcanic glass the main constituent of which is amorphous silica (70-76%). Perlite, when heated rapidly to its softening temperature range, expands from four to twenty times its original volume, due to the presence of 2-6% ?combined? water, in a manner similar to popcorn as the H2O molecules vaporize and create countless tiny bubbles, which account for its exceptional physical properties: light weight (30-150 kg/m3), low thermal conductivity, cellular structure, in general. These properties make perlite adaptable for numerous end-uses, which can be distinguished into 2 categories: Expanded perlite applications in: a) Construction Materials market (e.g. Acoustical Tiles, light-weight insulating Mortars, self-levelling Concrete), b) Agriculture (e.g. Hydroponics), c) Food and Chemical industry (e.g. Filtration Media, Filler, etc.), d) Insulation and Heat resistance technology (e.g. Cryogenic vessels, Refractory Bricks, etc.). Unexpanded Graded perlite applications in: a) Phosphoric Fertilizers industry (additive in H3PO4 production), b) Foundry technology (slag-aid, insulating and heat resistance agent).

Jan 1, 2006

By J. Gonzales

For this paper, blending is conceived as a linear process that takes a proportion from one stockpile or location and mixes it with another proportion from another stockpile or location, with the aim of obtaining a set of attributes in the final combination that satisfies a given quality standard. A blending class is the combination of ore attributes and grade limits that should be stockpiled in order to achieve the target quality for the process Plant. Current literature considers the number of blending classes in the Open Pit Scheduling Problem as fixed; however, this paper shows how to define specific blending classes for a given deposit so that the schedule can be solved with Sequential Linear Programming. Finally, a practical application in a Peruvian copper mine is shown, involving four ore attributes: alteration code, arsenic, oxide content and copper grade. INTRODUCTION In copper ore deposits, blending for quality has not been a typical issue as it was for coal and iron ore; however, current copper deposits in the world are becoming geologically and chemically more complex than in the past and is not uncommon to have quality standards involving up to four attributes, introducing an additional complexity to the mine scheduling process [1]. In order to solve the Open Pit Scheduling Problem with multiple ore quality constraints, two assumptions are necessary [2]: - Grade constraints are defined only by specifying an upper and lower limit; - Ore attributes in stockpiles are pre-determined, i.e., the upper and/or lower grade limits defining each stockpile are already known at the time of setting the schedule. Assuming each ore attribute is classified as high, medium or low, and there are four attributes to be controlled in the target ore quality, the number of possible blending classes would be 3^4 = 81. This number is impractical to manage in Operations, and increases the complexity at the time of running the schedule; therefore, a more efficient way of classifying ore is required. Note that in practice, one blending class can be split into more than one stockpile location due to physical capacity constraints. Therefore, the number of stockpiles could even be more than 81. BLENDING CLASSES DETERMINATION For a given set of ore grades with lower and upper limits to be achieved, one has to find all feasible ore classes such that when blended, their grades will lie within those limits.

Jan 1, 2019

By Carl G. Bock

INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has let a contract for the excavation of three rock stations, spaced about 3550' (1082m) apart, beneath Connecticut Avenue in Washington, D.C. Two previous rock stations have been completed, one of which had a crown pilot tunnel excavated to explore geologic conditions that would be encountered during the station excavation. This pilot tunnel was primarily for inspection by bidders and design was based on core hole information. The other rock station had no pilot tunnel and was also designed on the basis of core hole information. The three rock station areas, which are the subject of this paper, have been explored by crown pilot tunnels and an as-built report, with geologic maps and sections, has been prepared, for use by the design engineer as the basis of design for support of the structures. The geotechnical report describes the geologic structure in detail and relates it to excavation and support of the three crown pilot tunnels and the running tunnels which will be enlarged to create the 58'W x 44'H x 700'(+)L (17.6m x 13.3m x 212m +) stations. The information was complete enough to permit the design engineer to visualize the geologic structure and compute loads for the various types of rock conditions. It was therefore possible to determine the size and spacing of the steel sets for the several different conditions of rock structure encountered in the pilot tunnels.

Jan 1, 1976