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By B. Das

Hematite floatability from two low grade banded iron ores of India, namely banded hematite quartzite (BHQ) and banded hematite jasper (BHJ) using fatty acids and amine as the collectors is investigated under identical physico-chemical conditions. The results indicated that hematite present in BHQ ore is easy to float using both the collectors, compared to BHJ ore. The difference of flotability between the two banded iron ores is that quartz grains are coarser and well liberated below 100 micron size in case of BHQ compared to BHJ ore. In case of BHJ ore, fine hematite and quartz grains are intimately inter-grown and are dispersed in thick jasper bands leading to liberation problems. Besides that, dusty jasper particles coat over hematite surface in case of BHJ ore during the process of grinding, which hinders specific adsorption of collector on hematite or quartz surfaces. This is substantiated by scanning electron microscopy (SEM). The flotation studies have indicated that it is possible to achieve ~64% Fe with ~67% recovery from a BHQ ore using both anionic and cationic collectors from a feed containing around 38% Fe. In contrast, the hematite recovery in BHJ ore was poor. Differences in the ore characteristics that affect the flotability of hematite present in both the ores are compared. Keywords: Banded hematite quartzite, banded hematite jasper, flotation, oleic acid, dodecylamine, QEMSCAN, Scanning electron microscope

Feb 27, 2013

By Jameel Menashi

A process has been developed for recovering the refractory metal values contained in mixed secondary source materials such as contaminated grinding wastes, oxides and sludges. The wastes are calcined with sodium carbonate in air to convert the refractory metals to water soluble Na2CrO4, Na3V04, Na2Mo04 and Na2W04. The base metals, Fe, Ni, Co and Cu, are converted to water insoluble oxides. An aqueous leach of the calcine effectively separates the refractory metals from the insoluble base metals. Co, Ni and Cu can be recovered from the oxidic residue by conventional processing methods. The leach solution is purified and then treated to recover the refractory metals as Cr203, NH4VO3, (NH4)6Mo7024?4H2O and H2WO4. The purity of the products is sufficient for their use in many metallurgical applications. The Na+ values in the leach solution are recovered as Na2CO3(or NaHC03) and are recycled to the calcination step. It is shown that the process can accommodate a wide range of feed compositions and generates a minimum of aqueous effluents.

Jan 1, 1984

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

In this work, a new flotation strategy was proposed for the flotation of rutile. In this strategy, rutile was activated by Pb(NO3)2 and then floated with amyl xanthate (AX) as a collector at pH 8. Pb(OH)+ was the dominant lead species in the solution at pH 8 and is believed to be the major species reacting with the rutile surface. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) study revealed that the lead activation products were well distributed on the rutile surface, and AX− could further bind with the Pb atom on the Pb-activated rutile surface. In this regard, the Pb-activated rutile could be floated by AX. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(OH)2 was generated on the Pb-activated rutile surface. The electron transfer during the adsorption of the AX− on the Pb-activated rutile surface was also investigated by XPS analysis.

By Qinbo Cao, Qianshan Peng, Heng Zou, Xingcai Yu

In this work, a new flotation strategy was proposed for the flotation of rutile. In this strategy, rutile was activated by Pb(NO3)2 and then floated with amyl xanthate (AX) as a collector at pH 8. Pb(OH)+ was the dominant lead species in the solution at pH 8 and is believed to be the major species reacting with the rutile surface. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) study revealed that the lead activation products were well distributed on the rutile surface, and AX− could further bind with the Pb atom on the Pb-activated rutile surface. In this regard, the Pb-activated rutile could be floated by AX. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis indicated that Pb(OH)2 was generated on the Pb-activated rutile surface. The electron transfer during the adsorption of the AX− on the Pb-activated rutile surface was also investigated by XPS analysis.

By Aleksandar D. Bugarski, Dylan A. Ritter

The results of laboratory characterization of tailpipe emissions for three “clean” engines that meet U.S. EPA Tier 4 final emissions standards were used to assess the viability and effectiveness of repowering existing engines and powering new mobile equipment with those engines as a control strategy for reducing exposure of underground miners to diesel aerosol and criteria gases. The evaluated engines were representative of those that achieve the emission standards through implementation of various in-cylinder emissions control strategies, use of crankcase filtration, and use of three types of exhaust aftertreatment systems: (1) diesel oxidation catalytic converter (DOC), (2) combination of DOC and the full-flow wall flow monolith diesel particulate filter (DPF), or (3) combination of DOC, diesel exhaust fluid (DEF) based selective catalytic reduction (SCR) system, and ammonia slip catalyst (ASC). The study showed that the highest reductions in concentrations of diesel aerosols in underground workings, in terms of both mass and number, could be achieved if the engines, preferably in all power classes, are fitted with viable DPF systems. The use of U.S. EPA Tier 4 final engines equipped with DOC and DOC/SCR/ASC systems could help operators to considerably reduce mass, but not number concentrations of aerosols. The emissions of two of the evaluated engines, one equipped with DOC and the other equipped with DOC/DPF systems, were characterized by substantial secondary NO2 emissions that would limit the viability of those engines for underground mining applications. It appears that the catalyst formulations used in the exhaust aftertreatment systems of the “clean” engines marketed to the underground mining industry need to be formulated to minimize the potential for generation of secondary NO2 emissions. The results indicate that the engines fitted with viable SCR/ASC systems present a low-NO2 alternative. All three “clean” engines were found to have low CO output. Therefore, due to nuances associated with the use of diesel-powered mobile equipment in underground mines, special attention needs to be paid to the selection and potentially optimization of “clean” engines for underground mining applications.

Feb 1, 2025

A dedicated tunnel construction version of the Caterpillar 328D LCR compact radius excavator is proving highly productive on the A9 Autoroute construction project near Visp, in Switzerland. It is the first machine of its kind to operate on a Swiss contract and uses a special dedicated front attachment designed and constructed by German Caterpillar dealer Zeppelin. The machine offers a powerful, stable and compact solution for tunneling contractors. A rear overhang of just 305 mm (12 in.) provides a tail swing radius of just 1.9 m (6.2 ft). The 328D LCR is ideal for the restricted working areas within a tunnel construction site. The machine is equipped with the wide tracks from the 330D L conventional crawler excavator, ensuring maximum stability when operating. In addition, the boom mounting has been moved further toward the center of the machine for the tunnel model, creating an increased lift capacity over the front end compared with a standard 325D L. The boom itself features a robust box section construction, with high-strength steels, additional supporting struts and reinforced bearings for maximum durability. All pins have hard-chromium plating for optimum protection against wear. Stick digging force is a powerful 134 kN, with up to 212 kN of bucket digging force available, for maximum penetration in blasted material. The 328D LCR is also equipped with a heavy-duty dozer blade as standard. This ensures outstanding stability when working and providing a useful secondary tool for clearing and leveling within the jobsite. Two 45° tilting mechanisms in the boom construction, allow the boom to be swung to 45° on either side of the machine. So the specially designed attachment linkage provides increased rollback for access to the roof of the tunnel. A Caterpillar CW45S mechanical quick-coupler allows rapid changes between specialist tunneling attachments, standard Caterpillar buckets and a range of Caterpillar work tools. The machine is powered by a Caterpillar C7 diesel engine. This six-cylinder EU Stage IIIA diesel motor [ ] offers 8 percent more power than its predecessor, with 140 kW (190 hp) available at just 1,800 rpm. Caterpillar?s ACERT combustion technology results in lower fuel consumption and reduced exhaust emissions. However, the tunnel machine is also equipped with a diesel particulate filter as standard, to further cut exhaust gases within the tunnel working. The 328D LCR is designed for use in transport tunnels of 6.8 m (22.3 ft) in height. With the tunneling boom in place, the machine has an operating weight of 42,540 kg (93,783 lbs), yet retains a transport height with the tunnel boom of just 3.9 m (12.8 ft). Transport width with 600 mm (23.6 in.) track shoes, is just 3.2 m (10.5 ft). On the A9 tunnel contract, the machine is being used by a consortium of Swiss and Austrian companies working for the canton of Valais? Routes Nationals Construction (RNC) department. The 31.8-km (19.7-mile) A9 Autoroute construction project will connect Sierre in the west and the town of Brig to the east. The tunnel that is bypassing the town of Visp is just one of a number along the mountainous route.

Jan 1, 2009

By Jennifer B. Leinart

Sixty percent of the mines responding to the sixth annual Mining Cost Service labor survey reported increases in wages averaging 3.4% over the preceding 12 months. Only one mine reported a decrease in wages and this was accompanied by initiation of a substantial profit-sharing plan. Thirty-nine percent reported no change in wages. Thirty-seven percent reported using some form of incentive bonus plan. Mining Cost Service annually surveys coal, metal, and industrial mineral mines throughout the United States. Information about wages, benefits, and incentive bonus plans is part of an extensive data collection program to monitor cost areas of significance to the mining industry. This year, 131 mines responded to the survey. The data is collected by sending questionnaires to personnel managers at active mining operations. The information included in this article was taken from the returned forms, from labor contracts provided by some of the mines, and from followup telephone calls. This year's data was collected between November 1988 and February 1989.

Jan 1, 1990

By J. R. Dyni

Colorado nahcolite deposits, estimated at 29 billion metric tons, formed in an asp metric permanent-lake basin whose waters were rich in algae and sulfate-reducing bacteria. Nahcolite (NaHCOg) occurs in oil shale of the Green River Formation (Eocene) as aggregates (62 percent), disseminated crystals (24 percent), and impure beds (14 percent). Because much of the nahcolite is nonbedded, it will be mined with oil shale and can be concentrated to marketable grade by crushing and screening Impurities in nahcolite are kerogen, quartz, pyrite, and carbonate minerals. A promising new market for nahcolite is in the process of removal of sulfur dioxide from industrial stack gases. When heated, nahcolite reacts with sulfur dioxide to form sodium sulfate. Differences in thermally induced microporosity may explain why nahcolite is more reactive than trona, a possible competitor with nahcolite for SO2 removal. Limited production of nahcolite at one or possibly two localities is expected in the next several years, but large-scale production is probably at least 10 years away.

Jan 1, 1980

By James D. Cooper

Long range projections of demand for nonmetallic minerals are presented, together with data on the domestic resources which are available or which can be made available to meet the requirements through the balance of the century. Past successes in solving nonmetallic mineral requirement problems are briefly reviewed to illustrate the capability for solving present and future problems of a similar nature. Major problems threatening the future supply of specific industrial minerals are described together with possible methods for assuring the necessary raw materials for future needs. The growing importance of environ- mental degradation, land use conflicts, and other important factors which affect several or all of the nonmetallic mineral industries is covered, and the necessity of planning for efficient and orderly extraction and rehabilitation of mineral deposits is stressed. The present Bureau of Mines methods and tools for long range planning are briefly discussed.

Jan 1, 1969

By Jozef F. Zurawski

River Des Peres Foul water Interceptor (Skinker–McCausland Tunnel) is a gravity sewer tunnel constructed to eliminate dry sewage overflows during high river stages and to improve the wastewater collection and treatment. The original 78-inch (2m)finished diameter Skinker-McCausland Tunnel started as a 21,500 feet (6.5km)interceptor with 13 work, drop and access shafts. The tunnel constructions included soft ground, mixed face and rock tunneling in karst formation with maximum overburden of 175 feet (53m). Due to the success of the project, the tunnel alignment was extended another13,361 feet (4.1 km) and 7 new structures by negotiating two additional segments with the contractor and the designers.

Jan 1, 2001

By N. I. Aziz, I. Tague, P. Mackenzie-Wood

The recent mine disasters in Australian coal mines have initiated an introduction of Self-Contained Self-Rescuer (SCSR) as component in the development of new escape strategies for miners. These self-contained self-rescuers are closed circuit, demand sensitive breathing apparatus that make oxygen available to the wearer for a nominal period of time. Their operation is completely independent of the surrounding atmosphere. Once properly donned, the SCSR can assist a miner to escape from an area containing smoke, toxic gases or an oxygen deficient atmosphere. The duration of a typical SCSR is usually taken at the point of complete collapse of the breathing bag which is accompanied by an increase in breathing resistance and inhaled levels of carbon dioxide. Because the oxygen consumption (V02) and the heart rate are correlated, a prediction of V02 and consequently the duration of an SCSR can be made by monitoring the heart rate. Thirty-seven volunteers participated in field simulated escape trials at four underground coal mines. The results from the field trials suggested that oxygen consumption depends on the heart rate, the body weight and exercise rating of the miner. All the volunteers were asked to fill out the questionnaires to evaluate the performance of the units. The miners indicated that they could tolerate the inhaled temperature without any difficulty to breathing resistance. A complete statistical analysis of the field results is also presented.

Feb 24, 1997

By Harvey W. Parker

The underground industry is challenged by many complex technical and non-technical issues and risks. The most obvious of these are the traditional technical issues that we usually try to address with risk management techniques. However, there are many other non-technical risks that our projects face on a daily basis which we often fail to fully recognize or appreciate. This paper addresses some of the less-technical broad-based risks in order to put them into perspective with the technical risks we face day to day in underground planning, design and construction. The good news is that Risk Management techniques are not always about bad things. For obvious reasons Risk Management is always thought of in terms of the ?downside? of risk (i.e., the identification and mitigation of things that can go wrong). On the contrary, there is an ?upside? of things that might go better than expected. Fortunately, if a deliberate effort is made, the same principles and techniques that our industry uses in Risk Management can be applied toward identifying and quantifying the Opportunities and Benefits that might occur. In this way, the process of conducting risk management programs can not only identify the downside risk but can be used to identify and direct projects to take advantage of the upside of uncertainty (i.e., Opportunities as they arise). This beneficial aspect of risk management programs will be highlighted in this paper together with the importance of the non-technical issues.

Jan 1, 2008

By A. Jennings

[ ] In November 2005, Essroc Cement, part of the Italcementi Group, commissioned a long overland conveyor at their Nazareth plant in Pennsylvania. This conveyor, tagged CV-105, was designed to transport 1000 tph of limestone from the quarry to the kiln, and 400 tph of hot clinker (at 300°F) at back from the kiln to a handling facility about halfway back. Conveyor CV-105 is 8969 ft (2733 m) long. It gains 152 ft (46 m) of elevation in the first 1570 ft (480 m), then is mostly flat for the remaining 7400 ft (2250 m) (Figure 1). After the limestone is discharged at the head pulley, hot clinker is loaded onto the return side of the belt. This clinker can be discharged at one of two locations.

Jan 1, 2012

By Stephen Njoloma, William Bracken, Harald Cordes, Ivan Hee

"DC Water’s First Street Tunnel (FST) is part of the $2.6 billion Clean Rivers Project designed to reduce the occurrence of combined sewer overflows into local waterways. Due to flood events in the Bloomingdale and LeDroit Park neighborhoods, the FST Project was accelerated by DC Water to mitigate future flooding by boosting storage capacity and thus relieving the undersized combined sewers.The FST Project was finalized in 2016 as a collaborative effort between DC Water, its consulting team consisting of Greeley & Hansen and McMillen Jacobs Associates, and the design-build team of Skanska, Jay Dee Contractors (SKJD) with WSP Parsons Brinckerhoff as the designer.Scope of project. The FST Project (Fig. 1) included four primary shaft sites, a large 6 m (20 ft) internal diameter, 823- m (2,700-ft) long bored tunnel and three adit connections from the off-line shafts to the large-diameter tunnel. The adits which vary in size and length, are the subject of this article. The Channing Street site (Fig. 2) was established as the main site for an Earth pressure balance tunnel boring machine (TBM) and included a 49-m (160-ft) deep shaft with slurry wall support of excavation and 20-m (65-ft) internal diameter final cast-in-place permanent concrete liner. The construction sites at Adams Street, V Street and Thomas Street each consisted of off-line shaft structures tied to near-surface sewer diversion chambers and ventilation facilities. These three off-line shafts were connected to the large bored TBM tunnel via adit tunnels. Each of the three adits had a portion or the entire length excavated by sequential excavation method (SEM) in frozen ground.The Adams Street adit (Fig. 3) was constructed in two phases. The first phase is the 23-m (75-ft) long and 5-m (16-ft) diameter section immediately outside the drop shaft which also serves as the deaeration chamber and was excavated by SEM. The second phase which is 91 m (300 ft) long and 3 m (10 ft) in diameter was excavated by Micro TBM (MTBM) launched from within the permanently lined deaeration chamber. MTBM excavation commenced toward a reception chamber that was excavated by SEM from the previously bored FST TBM tunnel. This SEM excavation had a 5 m (17 ft) diameter and a length of 4.5 m (15 ft)"

Jan 3, 2018

By W. M. Middleton

The exploiting of geothermal steam is a new endeavor in this country and is for that matter a very new science in the world. With the majority of steam wells in the world having been drilled during the last twelve years relatively little experience and knowledge has been gained that can guide us as compared to the techniques the oil and gas producers have developed for their use. We few technical personnel associated with the field find it a continuous challenge to understand and explain what effects or causes the various unusual phenomenon experienced. We have had unending discussions attempting to formulate pet theories which we can use as guides. We know, so the geologists tell us, that the source of the heat is from the hot magmatic core of the earth. Theory has it that the magma is cooling off and that hot gases are given off as this magma cools and shrinks. In volcanic' areas along fault lines where the magma reaches closer to the surface than in other areas, there is a higher concentration of gas evolution; consequently, geyser or geothermal areas are developed. As these hot gases rise toward the surface they encounter various minerals, including overlying bodies of water. It is into these underground lakes that our wells are penetrating. As the heat enters these lakes it spreads out by conduction, convection and water migration. We can strike this hot water over quite large areas in many of the geothermal fields. At present there is one anomaly to this in the United States as there is in Italy where our wells do not penetrate a hot water lake. This is at The Big Geysers in California. Here superheated steam is produced with a heat content, so high that it could not have been boiled off of a fresh water pool. This puzzled us until last year when a well was completed into a large body of brine in the Imperial Valley. This brine exists at close to 500°F and at a hydrostatic pressure sufficient to preclude any boiling. It is now believed by some of us that a similar pool of brine must exist below The Big Geysers area, from which the steam is emanating. If there is such a brine pool, it offers a plausible explanation of the high-heat content, for brine boils at a higher temperature than fresh water. I am now beginning to think that a similar brine pool may exist under all the geothermal basins for if it is under two of them, it is highly probable that it is under the others. The partial understanding of what we are drilling toward, and formulating a theory to explain its behavior helps guide us in our steam well drilling.

Jan 1, 1963

By K. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 meters (1MPa, tensile strength) in the rock mass, a distance that is sufficient to impact the pit-scale slope over the long term. In addition, the damage zone was calculated using the reasonable assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone ? up to 5.6 meters (30MPa, 30% of the compressive strength) ? indicates that microfracturing can occur throughout the entire rock mass in the blasting area. Finally, an economic analysis was conducted by comparing two reasonably assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond?s law after increasing the blast energy from 180kcal/t to 350kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. An optimal blast design should consider both slope stability (safety) and downstream comminution energy (production).

Feb 23, 2014

By Graham Davey

High-speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However, it has been widely used in the industrial mineral field for more than 30 years. Many existing metallurgical operations are looking to maximize economic return from existing deposits this requires new thinking and technologies. The operating experience of two copper operations is discussed here to show the effect of the introduction of the Metso Stirred Media Detritor (SMD), a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from this new technology. The benefits and process difficulties are explained. The initial drive in high speed stirred milling technology was toward ultra fine grinding where the mill product has an 80 percent passing size of 15 µm (937mesh) or less. More recently, a number of installations have occurred in a more conventional regrind setting. Few conventional copper concentrators require such fine grinding to attain satisfactory copper grades and recoveries. So other advantages must be considered here rather than just the ability to grind fine with good power efficiency.

Jan 1, 2004

By William R. Yernberg

The 26th Peruvian Mining Convention (Convención de Ingeneieros de Minas del Perú) was held Sept. 15 through 19, 2003, in Arequipa. The convention was sponsored by the Peruvian Institute of Mining Engineers (Instituto de Ingeneiros de Minas del Peru). The Institute has been organizing these events since 1954. They are now held every other year. The conventions spotlight Peru’s mineral resources and have contributed to the tremendous growth of the Peruvian mining industry. This year’s meeting consisted of technical sessions, forums, field trips and social activities. It was held at the Tecsup Institute of Technology of Arequipa. More than 3,000 mining professionals attended. As always, the meeting was well organized, and participants expressed gratitude to the organizing committee for another successful meeting.

Jan 1, 2004

By Libby R. Ricafort, Victorio V. Pato, R. S. Pizarro

Introduction Atlas Consolidated Mining and Development Corp. (ACMDC) started gold production at its Masbate gold mine early in 1980. This involved an open-pit mine and a 3.5-k/d (3850-stpd) carbon-in-pulp processing facility (Pizzaro and Antonio, 1981). When this operation started, the mine began stockpiling sub-grade milling material averaging 1 g/t (0.029 oz per st) gold. Furthermore, geologists estimated that there were additional low grade reserves within the ultimate pit limits. These amounted to 2.4 Mt (2.6 million st) with an average grade of 1.1 g/t (0.03 oz per st) gold. The success of low cost heap leaching prompted an investigation to determine if this tech¬nique would be applicable for the low grade Masbate ore. The findings were favorable and a series of laboratory tests were undertaken. These tests indicated the amenability of this subgrade milling ore to heap leaching. Depending on ore size, gold extractions of more than 60% were obtained. To further define operating parameters for a commercial heap leaching plant, a 400-t (440-st) batch pilot plant was built and operated. These test results were used to design the first commercial heap leaching plant in the Philippines. One design concern was the control of solutions during the rainy season. Due to the material's low grade, every effort was made to minimize capital and operating costs. To this end, surplus mining equipment from the copper operations of ACMDC and used machinery in the crushing circuit were considered. Location: The Masbate gold heap leaching operations are located on the northeastern part of Masbate Island, Philippines. This is about 480 km (300 miles) south-east of Manila. Climate: The climate is moderate with two distinct periods. The dry season runs from January through June, and the rainy season extends from July through December. During the wet season, the rainfall at the mine site averages 300 mm/m (11.8 in. per month) for a total of about 2000 mm/year (78 in. per year). However, heavy downpours in excess of 100 mm/h (4 in. per hour) can occur. Geology: Four distinct rock types have been identified in the pit area. They are tuffaceous agglomerates, andesitic agglomerates, metasedimentary rocks, and hornblende augite andesitic porphyry. The tuffaceous agglomerate occupies the northern and western flanks of the mine. Andesitic agglomerates are localized distinctly in the central portion of the volcanic plug within the mine site. The eastern boundary of the mine is occupied by metasedimentary rocks, whereas, the hornblende augite andesitic porphyry occurs as an intrusive within the andesitic agglomerate and tuffaceous agglomerate. Some areas of the pit contain high proportions of clay minerals, requiring an agglomeration step in the flowsheet. This ensures satisfactory percolation through the heaps. Ore characteristics: Gold and silver are microscopically dis-

Jan 9, 1987

By Werner Burger

Earth Pressure tunnel boring machines are tackling difficult ground conditions that five years previous were not considered feasible. The technology has evolved that allows EPB TBMs to cross into areas that with the latest in conditioning and special design considerations are now possible to mine. This paper will review the various recent developments and those projects where these new techniques have been applied.

Jan 1, 2008