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By T. Knuutinen, M. Klemetti, P. Mörsky

This paper presents a comparison study done at VTT's new pilot plant facilities in Outokumpu, Finland, for chromite ore. The ore was ground in a rod mill -, a ball mill - and high pressure roller mill - ball mill circuit in the capacity range of 0.5 - 3.0 t / h. The main grinding characteristics are discussed and the quality of the products are compared from the mineralogical point of view. The benefits of high pressure roller mill comminution for further mineral processing of chromite is also discussed.

Jan 1, 1995

By J. L. Ellenberger, P. W. Jeran

A deep longwall coal mine was instrumented with a three-dimensional microseismic system in order to help determine the exact strata mechanics associated with the rock failure, redistribution of stress and the associated gob formation from the longwall. Overall, 5,000 well calibrated seismic events were recorded during the mining of the panel. Analysis of these events showed a close correlation between the seismic activity and advance rate, and that the majority of the recorded seismic activity occurs in the immediate area of the advancing longwall face.

Jan 1, 2002

By J. D. Patsey, G. T. Lineberry

A.E. Hall The authors are to be commended for their attempt to provide a convenient piece of software for preliminary drum hoist specification. This field has received little attention in recent years and is eminently suited to calculation by computer. Unfortunately, there appears to be an error in the calculation of the required rope diameter. The 66-mm (2 5/8-in.) rope selected is oversized for this application. Wire rope weight and breaking strength are related to the rope diameter. For a round strand rope

Jan 8, 1987

By David A. Rice, Scott A. Shuey, William K. Tolley

The U.S. Bureau of Mines (USBM) is developing new dewatering technology to permit the recycling of iron values contained in wet steel plant sludges. In laboratory tests, Q-BOP fume sludge was dewatered to 12% moisture by displacing water with acetone in a plate-and-frame pressure filter. Acetone is reclaimed through distillation at lower cost than conventional thermal drying of the sludge. The projected additional energy requirement for acetone treatment of the sludge, including acetone recovery, is $5 to $7 per dry ton.

Jan 1, 1995

By A. E. Isaacson

Bureau of Mines researchers developed and tested equipment to measure corrosion rates on a commercial-scale mill. Bench-scale experiments were designed for duplicating ore grinding conditions closely enough that realistic rate determinations can be made in laboratory tests. Rates measured in a laboratory system compared favorably with those measured in the field. Cast steel was found to have corrosion rates in a copper mill and laboratory test cell of 22 and 21 mpy, respectively. Corrosion was found to account for less than 5 pct of the total grinding media wear in the operations studied.

Jan 1, 1987

By Yuanhong Qi, Xun Fu Wang, Tao Fu, Kunkun Cui, Yingyi Zhang, Jie Wang, Junmao Qie

With the sharp decrease of sulfide nickel resources, the nickel laterite is becoming more attractive as nickel oxide, nickel matte, and nickel-iron. This study investigated the mineral phase structure, chemical analysis, thermal properties, and element distribution characteristics of the rotten rock layer deposited in the Southeast Sulawesi Ophiolite Belt. The results show that the nickel laterite deposited in Southeast Sulawesi Island, Indonesia, belongs to the typical high-nickel and low-iron garnierite-type laterite. The concentrations of nickel and iron of the nickel laterite are 1.99 wt% and 17.55 wt%, respectively. The serpentine, olivine, clay, chlorite, hematite, and magnetite are the major minerals, and the pyroxene, actinolite, limonite, and chromite are the minor minerals in the nickel laterite in Southeast Sulawesi, Indonesia. Serpentine and olivine are the main nickel minerals with an average nickel concentration of 3.65 wt% and 1.73 wt%, respectively. The Fe and Ni have homogeneity and symbiosis in the serpentine and olivine, and their concentrations are often positively correlated.

By Bruce A. Kuyper

Routine core drilling at the Cove deposit failed to confirm gold-silver grades and length of intercepts observed in reverse circulation drilling. A drilling program was designed to ascertain whether the disparity was due to problems with reverse circulation drilling techniques, core drilling techniques, or the erratic nature of the gold-silver mineralization. Special sampling devices and core drilling methods were employed. Data obtained from core-reverse circulation twins showed that down-hole contamination during reverse circulation drilling accounted for much of the variation between reverse circulation and core drill results. Down-hole contamination occurred as a result of high ground-water inflows eroding friable vein material from hole walls.

Jan 1, 1991

By G. J. Karabin

The Boundary Element Method of Numerical Modeling has become an increasingly popular rock mechanics -mine design tool. It has been used by the Roof Control Division, Pittsburgh Safety and Health Technology Center, MSHA, to aid in the resolution of complex ground control problems since 1985. This paper will present an overview of an evolving simulation process and details of methods utilized to generate necessary coal, rock and gob input properties. Also included is a description of a Deterioration Index System that is used to link model output to observed mine conditions and two case studies to illustrate that process.

Jan 1, 1995

By X. Zhu, L. Chen, R. Guru, M. Peiravi, M. Mohanty, L. Ackah, B. Xu

"The overall goal of this study was to develop a suitable flowsheet to extract rare earth elements (REEs) from coal ash. Only the findings from the first part of this study is being reported at this time. A total of fourteen coal samples of different ranks were examined for REEs concentration. An anthracite coal sample, originating from Pennsylvania having more than 700 ppm (in the coal ash) was selected for the REE extraction tests. The experimental program completed so far included high temperature leaching using nitric acid, followed by the solvent extraction tests. A 4x2x2 experimental design was used to conduct a total of thirty two high temperature leaching tests by varying acid molarity (at 4 levels), solid content (at 2 level) and leaching time (at 2 level). The highest LREE (light REE) recovery of 90% and HREE (heavy REE) recovery of 94% were obtained from the most optimum leaching test condition while maintaining the impurity recovery to the leachate at less than 40%. Solvent extraction experiments were conducted to recover the REE’s from the above leachate solution using a variety of organic extractants including, TBP, Cyanex, D2EHPA and their combinations. D2EHPA was found to be the best extractant during this SX text series providing nearly 99% recovery of REEs. INTRODUCTION The demand for rare earth element and other strategic metals (REM) in the world is rapidly increasing due to their use in a variety of high technology applications. More than 100,000 tons of rare earth oxides (REO) are being used worldwide on an annual basis. However, we have less than 10% of the world reserve of rare earth element (REE) mineral deposits in the US. More than 60% of rare earth oxide (REO) was imported to the US from outside (mostly from China) in the year of 2013. However, China’s institution of export quota has significantly reduced the supply of REMs to the U.S. Hence, new ways of producing REM and/or finding substitutes for those metals for the high-tech applications need to be invented/discovered in a timely manner. Coal Combustion Byproducts (CCBs), which are discarded as waste materials in most cases, are known to contain REEs (in low concentration) that could be extracted using a suitable process flowsheet. This may be a worthwhile route to pursue considering the short supply of REMs and the abundance of coal ash in thousands of ash ponds in the US. On an annual basis, more than 110 million tons of Coal Combustion Byproducts (CCBs) are being produced while satisfying our nation’s need for electricity (ACAA, 2014). However, less than 50% of these CCBs are being successfully used in various applications and the remainder is being dumped as waste materials in the landfills and ash ponds."

Jan 1, 2017

By David R. Klug, Chris Gause, Troy L. Page

The Inter-Island Tunnel is one of two undersea tunnels which are part of the Boston Harbor Clean-Up Program. The tunnel is 7.7 km (25,160 ft) long, bored to a 4.3 m (14 ft) diameter in the Cambridge Argillite Formation and was finished to a 3.5 m (11.5 ft) diameter final concrete lining. The owner is the Massachusetts Water Resources Authority (MWRA) who is a regional authority responsible for overall design and construction. The tunnel's primary purpose is the transport of untreated effluent from Nut Island facility in Quincy, MA to the new treatment plant at Deer Island. Two sludge lines are installed for the transport of sludge from Deer Island to Nut Island. During construction the contractor encountered fault zones, fractured strata, and soft ground tunnel sections which liberated more ground water than was originally anticipated by the project designer. Ground water was controlled during mining and the placing of the final lining. The final lining of cast-in-place concrete had to be backfill grouted to cut off water inflows and provide contact for equal tunnel loading which is critical in long-term design. This paper deals with an engineered backfill grouting system which was the first of its type to be used in North America. It discusses the geological conditions encountered, the design criteria used in the evaluation process, and an indepth review of the various system components. It demonstrates how contractors can use knowledgeable and professional industry suppliers to solve difficult construction problems.

Jan 1, 1999

By Ora H. Rostad

The sequence of events preceeding the discovery of the Mount Emmons molybdenite include some inadvertent near misses by several groups. The events are given in general chronological order to bring out the essentially contemporaneous, but different activities by several groups in two areas on opposite sides of Mount Emmons. The Mount Emmons molybdenite deposit lies in the Elk Mountain mining district. The west edge of the deposit is near the boundary between the Elk Mountain and Ruby mining districts as shown by the USGS map included (see Fig. 1). Considerable history regarding the Keystone silver-lead-zinc mine is given because of its proximity to the Mount Emmons molybdenite deposit which is on the other side of the mountain from Redwell Basin and where other significant activities took place. It should be noted that there was no documentary evidence available to me that would indicate that molybdenite was recognized to be present on, or under, any part of Mount Emmons, including Redwell Basin, before 1970. Veins containing silver-lead-zinc minerals were discovered in the Elk Mountain and Ruby mining districts about 1872. Some discoveries on the south flank of Mount Emmons about 1880 were developed into the Keystone mine. The Keystone has the largest cumulative production of metal ores of any of the mines in these districts. Most of the 413 Mt (455,473 st) of ore produced from the Keystone mine through August 1967 was produced after 1950. The ore averaged 175.4 gt (5.64 oz per ton) Ag, 2.62% Pb, 5.56% Zn, and 0.72% Cu.

Jan 1, 1991

By T. P. Lim, A. J. Vivyurka, N. K. Davé

Chemical and radioisotope stratification studies were carried out in an abandoned uranium tailings pile at Elliot Lake, Ontario, Canada. The tailings, with an average thickness of 7 m over an area of 16 hectares, were deposited approximately 20 years ago on a layer of black peaty material which overlays deposits of permeable glaciofluvial sands. Geohydro-chemical investigations of this tailings area have been ongoing since 1978. The radioisotope profile study was conducted on three adjacent sites. Solid core samples, collected with a split spoon sampler at various depths, were analyzed for various chemical and radioisotope constituents. The results indicated by 2 distinct zones of stratification; an upper zone, where the constituents were uniformly distributed, and a lower zone, near the peat-tailing interface, which showed increasing concentration with depth. Within the peat layer, the concentration decreased rapidly with no significant levels of contaminant penetration below the peat layers observed, though the samples were limited. The pH profile showed that the top 5 m of the tailings have been oxidized, the average soil pH in this zone was 3.4 compared to 5 .8 underneath it. The groundwater hydrology of the system was observed to be complex showing downward and lateral flow in the dry season and lateral and upward flow during the spring and periods of heavy rainfall. The results are discussed in terms of a model based on the combined segregation and settling process of the tailings fine fraction, and the geohydro-chemical interaction of the solid and liquid phases.

Jan 1, 1981

By S. H. Seyedein, Hamed Tavakkoli, Mohammad Reza Aboutalebi, S. N. Asharafizadeh

The liquid–liquid extraction behavior of lutetium from different acidic solutions was investigated using two extractants, D2EHPA and PC88A, in kerosene. Lutetium extraction reactions with D2EHPA and PC88A from HNO3 and H2SO4 solutions were chemically and thermodynamically analyzed. It was found that each Lu cation was complexed with six monomers of the organic extractant and released three protons. Simultaneously, the Lu cation was instituted in the P–O–H group of the extractants. Thermodynamic analysis of reactions between extractants and acidic solutions showed that the D2EHPA-HNO3 system is the most favorable for extracting lutetium. It is noted that the calculated equilibrium constant of the reaction in this system was approximately six times larger than that of the D2EHPA-H2SO4 system. However, the value of the equilibrium constant for the D2EHPA-HNO3 system was evaluated to be approximately 200 times greater than that of the PC88A-HNO3 system. Therefore, one can conclude that the extraction behavior of lutetium is more influenced by the extractant type than the solutionmedium. The synergistic effect of different mixtures of extractants on the solvent extraction of lutetium was also examined, and the highest synergistic factor was obtained for a binary mixture of PC88A:D2EHPA at the ratio of 4:1 for both aqueous solutions.

Mar 15, 2021

By Morris Loshinsky, George Ziegler

The New York City Transit System is celebrating its Diamond Jubilee this year. In 1904, 9.3 route miles of New York's first subway was placed in operation in lower Manhattan. Since that date the system has grown to 230 route miles and 458 stations (See Exhibit #1). The age of the system immediately provides a clue to the nature of our construction activity. While we must always plan for the future and expand the system in the direction of the future needs in New York, a substantial amount of time and money must be channeled towards the modernization and maintenance of the existing system which provides vital transportation for 3-1/2 million passengers a day. This paper however will be directed to our New Route's Construction and, specifically, to three rock tunnel and cut and cover sections presently under construction. Currently, New York is engaged in the construction of about 9 New Route miles of structure. Briefly, the 3 Sections we will discuss are as follows: Route 131-A Section 5A is a 4 track structure in Manhattan and includes the new Lexington Avenue Station. This 1240 foot long section is located between Park Avenue and 3rd Avenue and is a combined cut and cover and rock tunnel section under 63rd Street. Route 131-A Section 5B is an intricate 2423 foot long 4 track rock tunnel section extending from 3rd Avenue to the FDR Drive under 63rd Street in Manhattan.

Jan 1, 1979

By S. Ubaldini

Acid mine drainage (AMD) is a common problem in different areas with a past history of mining activities, which is characterized by low pH (2-4.5) and significant toxic metals concentration. The main aim of the present work was to perform a process feasibility analysis in order to remove heavy metals (Cd, Zn, Ni, Mn, Cu) from AMD (Acid Mine Drainage) in a relatively cheap and environmentally friendly way, by means of electrowinning and biosorption. A first characterization of an Italian AMD sample was performed evidencing a zinc concentration around 2 g/L, cadmium and nickel content of about 4 mg/L, manganese of 85 mg/L and iron 190 mg/L. Electrowinning tests lead to the following metal removal after three hours treatment: Zn 99%, Ni 99.9%, Cd 99.9%, Cu 99%, Mn 87%, Fe 96%. Moreover, an high grade of purity of the metal deposit has been achieved (Zn>95%), as observed by X-ray diffraction analysis. Considering that metals concentration in the effluent was still above legal limits (in particular for Zn, Mn and Fe), a further biosorption treatment was planned in order to produce an effluent fitting environmental limits. Experimental electrowinning tests and literature multimetal column biosorption data have been used in order to perform a preliminary techno-economic feasibility analysis of the process aimed at metal removal from AMD. A treatment cost of about 6.5 ?/m3 AMD has been estimated, for a plant capacity of 10 m3/h AMD inlet flow rate.

Jan 1, 2006

By K. L. Kayler

Ball clay production in 1991 amounted to about 800 kt (880,000 st), about the same as in 1990. 1992 estimates show a 5% decrease to 750 kt (827,000 st). This decrease continued a trend of reduced production that began after the peak of 900 kt (1 million st) that occurred in 1988. Use of ball clay in sanitary ware was about 2% less in 1992, although levels of use in floors and wall tile, dinner ware and pottery remained constant. Filler, extender and binder applications continued to be important end uses, accounting for about 17% of total market. Refractory uses maintained their market share of about 17 kt (18,700 st). Use of clay liners in toxic and waste dumps is an application widely found in Germany. However, its use has not been fully exploited in the United States. This could represent an opportunity for domestic clay producers. Tennessee remained the leading source of ball clays. Other producers were Indiana, Kentucky, Mississippi and Texas. Tennessee's production, however, decreased about 3% in tonnage produced and its value dropped from 68% to 65% of total production. The ceramics division of Southern Clay Products, Inc., was bought from LaPorte plc by United Clays of Texas, Inc., a US subsidiary of Watts Blake Bearne & Co. The purchase included ball clay reserves at Troup, TX. The acquisition makes United Clays the second largest ball clay producer in the United Sates. United is also the only company mining clay in Texas. Fire clay production decreased 5%

Jan 1, 1993

By Mark L. Bricker

The Jim Bridger Coal Mine, operated by Bridger Coal Co., is located in Sweetwater County, WY about 56 km (35 miles) northeast of Rock Springs. Bridger Coal is a joint ven¬ture between Nerco Coal Corp, the operator, and Idaho Energy Resources Co. The permit boundary encompasses more than 81 km'- (20,000 acres) on the western side of the Continental Divide. Since the mine began opera¬tions in 1974, it has produced about 82 Mt (90 million st) of coal while moving about 344 hm3 (450 million cu yd) of virgin earth. Annual production averages 4.5 Mt to 6.4 Mt (5 million to 7 million st) of run-of-mine coal. Coal is consumed on-site by the Jim Bridger Power Plant, a 2000-MW generating station. Electricity is transmitted to the Pacific Northwest power grid that includes Oregon, Idaho and northern California. Geology The mine is located on the northeast flank of the Rock Springs uplift. This is a broad, asymmetrical anticlinal feature about 97 km (60 miles) long and 56 km (35 miles) wide with a north-trending axis. This uplift separates the Green River Basin to the west and the Great Divide and Washakie Basins to the east. Precambrian rocks on the apex of the uplift are estimated to be 5200 m (17,000 ft) above the Precambrian rocks in the Green River and Washakie Basins. Normal faults with generally less than 30-m (100-ft) vertical displacement cut through the uplift. The dip of strata on the flanks is generally between 3° and 15°.

Jan 1, 1991

By James W. Martin, Robert R. Faddick

INTRODUCTION Virtually every sector of society in our country feels the impact of tunnels, either through the transportation of water, commodities, or people. The economic implications are staggering. The Committee on Rapid Excavation (1) reported that during the near future, 1968-1975, underground excavation activity will comprise 946 miles of tunnels (subways: 85 miles; underground urban highways: 123 miles; intercity highway tunnels: 210 miles; water supply tunnels: 528 miles) and 5,119 million tons of crude ore; metals: 874 million tons; nonmetals: 899 million tons; and coal: 3,346 million tons. It is estimated that the cumulative demand for underground excavation in the decade 1970-1979 will be 13 billion dollars for construction-oriented demand and 16 billion dollars for mining-oriented demand. The respective figures for the decade 1980-1989 are estimated at 22 billion dollars and 18 billion dollars. Of the many advantages claimed for tunnels (2, 3, 4, 5) the environmental considerations are becoming increasingly important. Transportation tunnels particularly for rapid transit systems, offer reductions in noise pollution and air pollution while improving aesthetics and optimizing land use (fewer problems of right-of-way and disruption of utilities). Considerable interest has been shown recently in sub-surface construction and mining (6, 7, 8). Recognizing the future demands for tunnels has led to considerable study of methods to improve rates of tunnel advance per day, safety, and the overall economics. The search for higher rates of advance has Led away from what has heap termed conventional methods (drilling

Jan 1, 1974

By James S. Redpath

"The ways of the world be many and most of the ways be tried, you follow in the footsteps of others till you come to the great divide". These words, written by Robert Service a long time ago, come to mind when I think of our original attitude upon entering into a contract with the International Nickel Company to sink the deepest shaft in the world outside of the Union of South Africa. This shaft was to be sunk to a depth of 7,137 feet from surface, and while it was recognized by all concerned to be a somewhat unusual undertaking in our part of the world, the fact that quite a few shafts had already been sunk to this depth in South Africa probably gave us the feeling that we were following in the footsteps of others. In retrospect, because this shaft was being sunk under entirely different conditions than those existing in South Africa, we were in fact venturing into an entirely new area of endeavour without properly recognizing this fact. It has occurred to me that others considering a similar type of job could benefit from our experience, especially in an assessment of the risks involved and how they compare to those encountered in an ordinary shaft. For comparison purposes, I would define an ordinary shaft as being sunk to a depth of 5,000 ft or less, and a deep shaft as one being sunk to a depth of between 5,000 ft and 8,000 ft. The sinking of the Creighton No. 9 Shaft has been de-

Jan 1, 1997

By Kenneth W. Torpey, James G. Ball, Richard F. Flanagan, David S. McAllister

INTRODUCTION Under a Federal grant by the Urban Mass Transit Administration (UMTA) (80%), and sponsored by the State of New York (200), Niagara Frontier Transportation Authority is constructing a 10.3 km (6.4 mile) light rail rapid transit system in Buffalo, New York. The $450 million project, which began construction in the Spring of 1979, is unique in rail transit alignment designs in the U.S.A. and the first predominantly underground light rail system in North America. The Buffalo project is unique in that the first phase of the expandable system follows the alignment of Main Street and is on the surface in a proposed 1.6 km (1.0 mile) pedestrian mall in the downtown business district. The alignment then progresses northward into a cut-and-cover portal and standard double-box configuration for 2.74 km (1.7 miles) at a depth of 9.1-10.7 m (30-35 ft) and subsequently drops into bedrock at depths of 18.3-27.4 m (60 to 90 ft). The 5.63 km (3.5 mile) rock tunnel section consists of two single tunnels 4.88 m (16.0 ft) nominal finished diam. and includes five stations. The rock tunnel line section was divided into a north and south contract of 2 316 m (7,600 ft) and 3 243 m (10,640 ft), respectively. Due to the existing surface facilities and the future station locations, the line tunnel contracts differed considerably in their shaft access

Jan 1, 1981