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By Hans G. Kok

At this time in the history of engineering and construction, cost indexes give weekly evidence of the sharply rising costs of labor and materials. Paralleling the rise in construction costs are the costs of plant maintenance. Automation of the modern industrial plant has permitted a substantial reduction in the total number of employees required for plant operation. Of this reduced total, however, up to one-half of the employees may be engaged in plant maintenance. Management's decision to risk investment capital for a pro- posed plant or improvement is increasingly dependent upon the engineer's ingenuity in designing plant systems and structures which will require a minimum of materials and labor for manufacture, installation, and operation and which will be maintenance-free to a maximum degree. This paper concerns itself with the structural elements of bulk material handling systems in which the foregoing factors influenced the design to a considerable extent.

Jan 1, 1969

By N. Bat, N. Sarantsatsral

Blasthole sampling practices were investigated at the Erdenet copper and molybdenum mine in Mongolia to address grade reconciliation issues. The goal of the study was to determine if the particle size distribution (PSD) of blasthole cuttings was accurately reflected in the samples. The study additionally examined if the measured grade was related to the particle size of samples. Using a sector sampler specifically designed to collect samples for the study, six large samples were collected from three blocks following a specialized protocol. Each sample was split into nine size fractions, ranging from larger than 12 mm to smaller than 63 µm. Copper and molybdenum grades were determined for each of the size fractions. For comparison, nine samples were collected from the same blocks following the standard mine sampling protocol. These samples were also split into the same nine size fractions. As with the other samples, grades were determined for each of the size fractions. The results showed that the PSD in the samples collected following the standard operating procedure varied significantly from sample to sample. This variation was much lower for the samples collected following the specialized protocol. Loss of fines was also indicated in the standard mine sampling process. These observations suggest that the standard sampling protocol did not consistently capture the PSD. The copper and molybdenum grades increased as particle size decreased, regardless of the sampling protocol used. This observation underscores the importance of the PSD of a sample being representative of the true PSD. Given the low number of samples in the study, it is not a strong conclusion that the standard sampling protocol captures the PSD inconsistently. However, it could be taken as a caution. On the other hand, the grade versus PSD relationship is more certain, given that it was observed regardless of the sampling method used.

Feb 1, 2017

By Robert W. Leonardson

The Questa Molybdenite Mine provides a unique opportunity to study the geochemical dispersion of various hydrothermal events, utilizing drill hole analyses. Numerous post-ore factors have altered the primary ore-related geochemical dispersions to the present day configuration, e. g. dikes, faults, hydrothermal convection cells, and weathering. Due to the interaction of an andesitic volcanic pile with the silicic-alkalic generated volatiles, the geochemical haloes of the Goat Hill deposit demonstrate a marked divergence from the classic Climax-type molybdenite ore body. Certainly, however, the similarities to the Climax-type ore body are apparent as potassically-rich fluids have invaded the highly reactive country rock.

Jan 1, 1984

By K. Oraee

Excessive emissions of methane from the coal seams can have a serious adverse effect on both safety and productivity of longwall coal faces. Mechanization of coal faces has increased production possibilities to the extent that normal ventilation systems may not be able to ventilate coal face areas in order to lower methane content in the air to within legal limits. Production increases may therefore be prohibited for this reason, especially in gassy seams. Methane drainage from the coal seam by means of long holes and before production starts can act as a useful remedial action. In this paper a two dimensional mathematical model has been produced. The model that is based on finite elements, simulates a methane drainage system where the resultant risk is linked to the coefficient of diffusion, coal permeability, holes pattern and the duration for which the seam is subject to drainage. It is concluded that methane drainage of this type can assist in achieving production increases in many coals seems, especially where high gas content is a virtue of the seam.

Jan 1, 2010

By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

By Andrew Chegwidden, Tara Wilk

Shaft 18B-1 is the second shaft to be constructed as a part of contract C547A along the New York City water supply system Tunnel No. 3. More complex than Shaft 17B-1, this site has an additional 30 m (100 ft) of overburden for a total excavation depth of approximately 78 m (256 ft) through water-bearing overburden soil and 145 m (475 feet) of gneiss bedrock to connect to the underlying Water Tunnel No. 3. round freeing was specied as the method to provide temporary earth support and ground water control for the overburden material. An extensive supplemental geotechnical investigation (SGI) and frozen soil testing program was performed to develop the design of a temporary ground freezing system, consisting of over 7,315 m (24,000 ft or 4.5 miles) of drilling for the installation of 95 freeze pipes. At the start of shaft excavation, the upper sandy silts strata was found to have an unprecedented low thermal conductivity, leaving the frozen soil face approximately 0.6 to 1 m (2–3 ft) behind the cutline. The ground freezing earth support needed to be augmented with ring beams and liner plates to support this soil face and allow for the excavation to proceed and be completed safely.

Jun 23, 2024

By E. Yigit

Hydrometallurgical production of zinc from concentrates is generally carried out by H2SO4 leaching. For the smooth operation of this process, some harmful components must be removed from the leach solution before the electrolysis stage; MgO is one of these compounds. Zinc concentrate samples from the Mount Isa mines were used in leaching tests. Leaching tests with an aqueous solution of H2SO4 and SO2 gas were carried out at various temperatures, pH levels and leaching durations. While duration and the pH value of the solution were effective parameters in H2SO4 leaching, temperature and pH were more effective in SO2 leaching for the removal of MgCO3 and CaCO3. Removal of MgCO3 and CaCO3 was generally achieved at low pH values. The results show that SO2 gas can be a good alternative to sulfuric acid in the leaching of MgCO3 and CaCO3

Jan 1, 2010

By Manoj Kumar, Anil Kumar Singh, Prabal Patra, Ashish Agrawal, Souvik Ghosh, Subhashis Kundu, Kamma Ramakrishna Rao, Manish Kumar Gupta, Anindya Sarkar

The slag measurement systems in the cast house are very important. In the conventional method, the slag is granulated in a slag granulation system, and the slag flow rate is measured by the associated belt scale. However, in places where a slag granulation system is not available, the alternate approach is to deduce a theoretical calculation and develop the measurement because the commissioning of such slag granulation requires huge capital and has inherent geographical limitation. However, the theoretical approach suffers from several drifts and is far from the reality. In the present paper, we have innovatively engineered a sensor by designing the stellite-coated thermocouple that can measure the temperature of the slurry and placed it in such a way that the abrasive slag granules do not obstruct it, but we could measure the temperature of hot water, and further based on the thermodynamic approach, the slag flow rate is determined that can be compared with the theoretical approach. This approach of slag rate measurement is cost-effective and long-lasting.

Oct 2, 2023

Underground instrumentation and observations at longwall panels have demonstrated that the growth of main roof causes an extremely high roof weighting on the shields. It can sometimes result in catastrophic effects on the support when the roof weighting intensity far exceeds the support capacity. In this paper, a comprehensive study was conducted on characteristics of main roof breakage and its effects on shields at different locations, based on the monitored shield data, theoretical analysis, and finite element analysis. With the help of theoretical analysis and numerical modeling, stress distribution and redistribution in the main roof were analyzed in detail to define main roof failure modes and understand the maximum roof weighting intensity imposed on the shields. From this study, it was found that the effects of main roof breakage on shields are chiefly related to the shield initial setting condition and the final failure mode of the main roof.

Jan 1, 1994

By M. J. Hrebar

Surface coal mine design has traditionally relied on graphic and analytic approaches for pit layout and equipment selection. A number of interactive graphic microcomputer programs have been written which aid in the design process in the academic arena and should also have industrial applications. The programs described include a dragline cut diagram and production index calculation program, a downslope load scraper cut diagram and volume program and an overburden volume and coal tonnage sequencing program.

Jan 1, 1985

By Edward J. Harvey

Joplin, one of the most famous zinc mining camps of a bygone era, is today experiencing a healthy growth in manufacturing enterprises. Manufacturing requires water, and knowledge of its availability and quality often is the main factor in location of industry. For this reason in January 1964, on the suggestion of the former State Geologist, Dr. Thomas R. Beveridge, a study of the water resources of the Joplin District was undertaken as a cooperative effort of the Missouri Geological Survey and Water Resources now under the direction of Dr. William C. Hayes and the U. S. Geological Survey. The project area is in southwestern Missouri on the Springfield Plateau and is bordered on the west and north by the Osage Plains of Kansas and Western Missouri, (fig. l). Upland altitudes rise from 900 feet above sea level in the west to 1400 feet in the east. The countryside is rolling to moderately hilly and much is excellent farmland.

Jan 1, 1965

By Victor Phillips

The Humphrey Preparation Plant of Christopher Coal Company, located in Monongalia County, West Virginia, was built to process the combined production of the Pursglove No. 15 and the Humphrey No. 7 Mines. Both Mines operate in the Pittsburgh Seam, primarily producing Metallurgical Fuel destined for by-product ovens in the Pittsburgh District. The results of an extensive core-drilling program have established sufficient reserves of low-sulfur coal to justify a 20,000 ton-per-day preparation plant, This is the story of the preparation phase of this combined operation. Christopher Coal Company operated the Pursglove No. 15 Mine to produce steam coal, which was prepared in a conven-

Jan 1, 1958

By Chris D. Breeds

Northwest Boring, Inc. (NWB) deployed a skinned up AVN 2000AB Microtunnel Boring Machine (MTBM) to install 7.5-foot long, 118-inch outer diameter reinforced concrete pipe (RCP) sections along an alignment between the Fremont (FRS) jacking shaft and the 3rd Avenue (3RS) receiving shaft for the Ship Canal Water Quality SCWQ Project. The alignment includes: a 67-foot long straight section, a 367-foot long curved section excavated along a 650-foot radius curve, followed by a 182-foot long straight section. This paper describes the project including planning and design, manufacturing, equipment installation in the 90-foot-deep FRS jacking shaft, egress through the secants and microtunnel operations required to complete the shaft and install the required casing pipes.

Dec 1, 2022

By L. W. Laage

MFIRE is a mine ventilation and fire interaction computer simulation program. It allows transient state ventilation simulation and features mass based flow rates, natural ventilation, air recirculation, fan curve fitting, airflow reversal and product of combustion tracking. MFIRE was designed to accommodate the needs of the mining industry for routine ventilation calculations and mine emergency planning. This paper describes recent work by the Bureau and MTU to improve MFIRE by incorporating humidity in the mass flow and heat exchange calculations, a data file preparation program and variable reference density in the network calculations. Recent bug fixes are also discussed.

Jan 1, 1993

By John B. Mitchell

Approximately 90% of all potash produced is employed as a fertilizer, either directly or with nitrogen and phosphorus. The remaining 10% is utilized in the manufacture of other chemical products, The original source of potassium was wood ash (hence the name potash), However, today the term potash refers to all commercially important salts of potassium. Sylvite, usually found associated with halite, is the predominant economic potash mineral; carnallite a lesser important source of potassium chloride, while langbeinite is important as a source of potassium sulphate. The world's first potash mining operation commenced in Strassfurt, Germany about 1860, Since that time the industry has grown steadily to its present annual volume of about 30, 000, 000 tons of potassium chloride products or 18, 000, 000 tons of K2O equivalent, potassium chloride or "muriate of potash" being equivalent to 63. 1% pure K2O, WORLD POTASH RESERVES ARE NOT EVENLY DISTRIBUTED The earth's crust contains 2 to 3 per cent potassium, mostly in the form of insoluble silicate minerals. The economically important deposits, however, are formed from brines concentrated by evaporation. The world's most important commercial deposits are of Devonian and Permian age, however soluble potassium bearing salts are presently being concentrated by evaporation in several drainage basins, notably Searles Lake, California, Great Salt Lake, Utah' and in the Dead Sea. At least twenty-four countries are known to have reserves of potash: Canada and the USSR have over 80% of the presently known world reserves, (Figure 1)

Jan 1, 1972

By P. A. Rittenhouse

Reserves of potash are more than adequate to meet future world demand for this primary fertilizer nutrient. The bulk of both reserves and current production is located in only a few countries. Recent attention has focused on potential development of smaller reserves to supply local markets in developing areas of the world. However, most new capacity in the next decade will be built in countries with large current production and reserves. The paper reviews current and future projects that will add to the world supply of potash.

Jan 1, 1985

By J. Alderman

In modern industry, cost and productivity concerns and environmental concerns are sometimes incompatible, but at other times only appear to be incompatible. Surface disposal of wastes from coal preparation plants appears to be an area of the production system with little opportunity for initiating measures which cut costs and concurrently benefit the environment. However, improving the recovery efficiency of fine coal circuitry can cost-effectively reduce the plant waste environmental burden by a substantial amount. Studies at Jim Walter Resources indicate that fine-coal waste measuring 50% ash contains over 50% recoverable, marketable coal. Modifications to the plant circuitry which reduce the amount of misplaced coal in the fine-coal waste stream could substantially reduce the volume of fine waste disposed aboveground. Studies at Jim Walter Resources indicated that episodic overloads of the vacuum filters in the fine-coal circuits at the preparation plants were a source of misplaced coal in the fine-waste stream of the cleaning plants. To improve the filtration rate and reduce overload episodes, conventional rotary blowers were replaced with high pressure air blasters on most of the filters. Subsequent testing indicated that measurable benefits can be derived from this modification.

Jan 1, 1990

By Hung-Kei H. Lam

Rubidium and cesium were discovered by Bunsen and Kirchhoff about 100 years ago. These two elements are by no means as abundant as sodium or potassium. Their occurrence in minerals is widespread, but usually as minor constituents. There is no known specific ore containing rubidium, but rubidium is found replacing the. other alkali metals in .some minerals.. Perhaps the highest concentration of rubidium found in one mineral is in lepidolite, KLi(OH,F)2A12Si3010, which contains from 0 to 3.5%*Rb20. 0n the average, lepidolite contains about 0.5% Rb20. Other sources of rubidium are carnallite, KMgCl3?6H20; pollucite, H20.2Cs20.2AI203.9SiO2; rhodizite, R20.2A1203-3B203; biotite, H2K(Mg,Fe)3A1(Si04)3; sea water, rivers, marine and fresh water organisms, soils, and plants. Cesium, even though it is the least abundant. of the stable alkalies, has a specific ore. Pollucites a hydrous cesium aluminum silicate, may con¬tain as high as 42.5% Cs20, although again, the average Cs20 content is about 25% among the handful of known deposits. Other cesium-containing minerals are lepidolite and carnallite. Rubidium and cesium are very much like potassium in chemical properties, consequently, they are hard to separate. Because of the difficulty in obtaining pure cesium and rubidium compounds coupled with the scarcity-of supply, prices were high and the two elements enjoyed little industrial use. Just before the Second World War, the world. supply of rubidium and cesium, from Germany, was a matter of tens of kilograms per year and prices were about

Jan 1, 1959

By Clément F. Bernier

One of the chief sources of the world's supply of asbestos lies in a belt of ultrabasic rocks which runs northeastward through an area called the Eastern Townships, south of the St. Lawrence River in the Province of Québec. The productive portion of this belt extends from the town of Asbestos in the south, for a distance of some 9,5 km to beyond the village of East-Broughton. The first discovery of asbestos in this region was made in 1874. Only crude fibre was produced until 1888 when the first mill was erected near the town of Black Lake. Since the inception of the industry, almost 100 years ago, no less than 100 different compa¬nies have been formed and 46 different mines have been operated. There are presently 5 active companies in the area providing direct employment for 4100 workers, down from 6000 during the seventies.

Jan 1, 1984

By S. K. Kawatra

In many mining operations, particularly northern open-pit mines, large seasonal variations in grinding slurry temperature can occur. It is shown in this paper that this temperature shift can cause a winter-time loss in autogenous grinding efficiency of as much as 20Y. if it is not controlled. Laboratory experimentation indicates that much of this effect is due to increases in slurry viscosity as the temperature is decreased. An additional effect may result from changes in rock strength upon freezing, for which possible mechanisms are discussed. However, no effect clearly resulting from rock strength changes has been definitely confirmed.

Jan 1, 1990