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By V. Sastry

Signgareni Collieries Company Ltd. is operating the JK Opencast Project, at Yellandu, with a rated annual capacity of 1.6 Mt of coal with an average stripping ratio of 4.3. This opencast coal project has three working sections, OC-II block, C-Block and D-Block These workings are operating in close proximity to the JR-5 Longwall Shed, 26-Dip Incline, other structures of 26-Dip, and a Township. There were complaints about ground vibrations and fly rock problems caused due to blasting operations, especially in OC-II and D-Blocks. In view of this, studies were taken up to eliminate the problems of ground vibrations and fly rock.

Jan 1, 2001

This paper discusses considerations to be made for the selection of rock tunnelling machines, as opposed to drilling and blasting. A systematic approach is presented in terms of utilizing data frcm site investigations to accurately forecast machine performance for estimating and planning purposes and to help minimise associated risks. Useful rock index properties are identified, and correlations for predicting advance rates for roadheader and full face machines are presented together with a simple method of characteristing rock mass conditions for estimating machine utilization and the savings to be gained in support costs. Finally considerations for tunnelling in adverse ground, for advance probing and for large sized tunnels are outlined.

Jan 1, 1987

Hindered settling devices (teeter bed, up-current) are widely used in the mining industry to classify mineral streams into various size fractions and to separate minerals. In the coal industry these devices are extremely successful in separating coal of low densities from shale and pyrite. In the beach sand and in the iron ore industry, this equipment is used to beneficiate minerals either as stand alone units or lately as classifiers in spiral circuits. The challenge that these applications give to metallurgists is to be able to simulate the equipment by using mathematical models with or without the aid of small bench scale tests. In any green fields and many brownfields projects, limited amounts of samples make pilot plant tests difficult. Although there are mathematical approaches available, the accuracy is of such a nature that it can not be used for design purposes. This refers to the use of StrokeÆs law, NewtonÆs and the so called intermediate law as is widely published. Research done by the author indicates that in most applications none of the above laws apply. Using the original data as published by Perry and Chilton (Chemical Engineering Handbook, pp 5-64, 1973) and re-plotting it indicates that the settling velocity of particles is a function of (particle diameter)n where n varies between 1.2 and 1.6 which is different from that predicted by the intermediate law that suggests that n = 1.18. Another way of describing the relationship between the drag force and the Reynolds number is done by iterating between settling velocity and the Reynolds number. This needs more computer time but the accuracy obtained from this does add value to simulations. A small but simple test is suggested to determine the settling velocity of particles to enable metallurgists to determine variations from the theoretical calculations to determine the influence of viscosity and particle shape.

Jan 1, 2008

By J. E. Nesset, E. R. Bobicki, K. L. Bilaniuk

The introduction of froth flotation technology in Canada, and in particular, in British Columbia, began not long after it was successfully applied in the Broken Hill mining area of Australia which began around 1905. It proved to be a revolutionary and transformative technology that resulted in marginal operations in copper, lead and zinc becoming profitable in spectacular fashion. The paper presents the technology of both oil flotation and froth flotation in the context of the challenges of the time and its early application in British Columbia at the Le Roi No.2 mine (1903), the Britannia Copper mine (1912), and at the Allenby concentrator of the Copper Mountain mine (1918-19). New-found archival documents indicate the Britannia application to be the first production application of froth flotation for copper ore outside Australia, a claim that is currently made by the Braden mine (now El Teniente) in Chile. Flotation was initially an add-on process following gravity methods but was rapidly shown to be far superior method for the bulk and selective recovery of metal sulphides. Flotation proved particularly successful for the recovery of zinc sulphide (the so-called ‘zinc problem’) which was considered a contaminant at the time. The ‘copper problem’ related to the poor recovery of fine copper sulphide particles that were not amenable to gravity methods. The success of flotation led to changes in both the scale and methods of mining, concentration and smelting in a manner that allowed integrated mining companies to flourish. Many are still with us today. INTRODUCTION The advent of froth flotation in the early 20th century was truly a revolutionary technological development, not only for the mining and metallurgical industries, but arguably more so for business and society overall. The Canadian technology historian Jeremy Mouat stated (1996) “The development of flotation was the greatest single metallurgical improvement of the modern era...it is not overstating the case to claim that flotation was of central importance to the smooth functioning of the global economy”. It should, therefore, be a story of interest to us all. The aim of this paper is not to retell the full story, that has been well covered by others (Hoover, 1912; Rickard, 1916a; Hines & Vincent, 1961; Lynch et al., 2010) but rather to add some Canadian perspective and the key role played by companies and individuals in those early days, focusing on events in British Columbia’s copper industry. EARLY DEVELOPMENTS During the later half of the 19th century, a number of flotation-related patents were issued. These include the 1860 patent (Britain) granted to William Haynes for a process to separate sulphides from ground ore by mixing it with oil (1-10% wt) followed by a separation process in a water-filled vessel; the 1877 patent granted to Georg and Adolph Bessel (Germany) for a process involving the mixing of oil and graphite ore followed by boiling in water to produce a high grade graphite froth (>90% carbon); and the 1885 patent granted to Rebecca ‘Carrie’ Everson for the separation of sulphides by mixing sulphide ore with small quantities of oil, and adding water followed by sulphuric acid. These processes are more properly referred to as bulk oil flotation due to the relatively large quantity of hydrocarbon used.

Jan 1, 2019

Optimisation and sensitivity analysis of final pit limits is now an accepted procedure for open pit planning studies. Tools to assist the design engineer in an underground metalliferous mine to make optimal choices for the selection of major development, stope geometry and cut-off grade analysis have not been available. The engineer has had to rely on experience and a limited analysis of design alternatives. A new tool called the `floating stope' has been developed to define the optimal (boundary) limit for material that can be economically extracted by underground stoping methods. The method is analogous to the `floating cone' method of open pit optimisation. The geology and mineralisation are modelled as a regular or subcell block model. Included in the model are structural and geotechnical features, and any previously mined out areas. Inputs to the procedure include the minimum stope dimensions, cut-off grade, stope head grade, and the way in which dilution is to be calculated. The optimisation procedure can be directed to maximise ore tonnes, grade, contained metal or the economic (dollar) value of material mined. The procedure can be applied at each stage of mine evaluation and design to assist with preliminary resource appraisal, selection of stoping methods, and detailed mine design. As with open pit optimisation procedures, manual intervention by an experienced engineer is required to produce practical and detailed designs. This practical design should follow the optimised design as closely as possible. The paper outlines the algorithms used in the definition of the stope envelope, and describes the analysis and results of several case studies where the optimisation procedure has been applied.

Jan 1, 1995

By C. M. McCulloch

As part of the Bureau of Mines methane control program, the Pittsburgh coalbed was studied in Washington and Green Counties, Pa., and in Marion and Monongalia Counties, W. Va., where this coalbed is now being mined at its greatest depth. The coalbed thickness appeared to be structurally controlled; the bed was generally thinner near the axes of anticlines and thicker near the axes of synclines. The overburden isopach shows a similar relationship. Most of the clay veins in coal occur in the synclinal troughs, generally under sandstone roof. Cleat orientations measured in 18 underground mines showed that face cleats are perpendicular to the axial trends of the folds, and the butt cleats are parallel to the axial trends, indicating structural control of the cleat. Measurement and analysis of surface joint orientations provide a method for predicting the cleat orientations of the coalbed, but linears measured from infrared photographs and photoindex sheets helped only to determine regional trends. The results of these investigations provide a geologic framework for rational planning for underground mine development to use the best available technology to cope with methane emissions, coalbed discontinuities, and related ground support problems.

Jan 1, 1975

By J. B. Ackerman, J. D. Miller

Alunite [KA13(S04)2(OH)6] is a promising non-bauxitic aluminum resource, the domestic reserves of which are estimated to be 800 x 106 tons at 35 percent alunite. The major gangue mineral associated with alunite is quartz. The thermochemical process that has been developed for treatment of this ore does not provide for the initial removal of gangue prior to processing. In this regard, it may be desirable to concentrate the ore to gain significant technical and economic advantages. Experimental results indicate the effectiveness of an oleic acid flotation technique and exemplify the problems encountered in fine particles processing. These results show that the quality of separation studied as a function of temperature, collector addition, and depressant addition is dependent on the degree of liberation achieved during size reduction. At coarse grinds the quality of separation was limited by the presence of locked particles while for finer grinds where more extensive liberation is achieved, better separations were obtained. The degree of liberation for each size interval was determined by an SEM/energy dispersive x-ray technique and found to be independent of the extent of size reduction, suggesting that liberation occurs by indiscriminate fracture and not by detachment. Up to 89 percent liberation was realized for a minus 400 mesh grind. Under these circumstances, the quality of separation appears not only to be limited by the remaining locked particles, but, also, by contamination of the alunite concentrate with fine quartz gangue (< 2µm). The best separation for the minus 400 mesh grind was a rougher recovery of 88 percent with a grade of 65% alunite at 50°C.

Jan 1, 1980

By G. Sedelnikova, D. Kim, N. Ibragimova

"The object of this study was three samples of sulfide old tailings, which were obtained after Cu- Zn ores processing. Fine metal dissemination in sulfides as well as fine mineral intergrowth determine the refractory nature of material and low metal extraction using simple methods: gravitation 1-6%, flotation 32-48%, cyanidation 10-37%, and cause the need to use sulfide bio-oxidation to liberate gold and to recover it by heap leaching. The gold is the main valuable metal in the tailings with content 1-1.5 g/t. Heap bio-oxidation with mesophilic and moderately thermophilic bacteria was used for pre-treatment of tailings before gold heap leaching from bio-oxidation solid residues. The tailings have a low permeability < 0.3-1.2 m/day, which is caused by migration of fine particles, decreases recovery rates, and is poorly suited to heap bacterial leaching. Therefore, preliminary gold sulfide tailings with permeability < 0.3 m/day were pelletized using copper containing flotation tailings of converter slags and calcium oxide. The most gold extraction was obtained for pelletized tailings. The base metals (copper and zinc) were precipitated from bacterial solutions. Experiments have demonstrated effective bio-oxidation of all third gold sulfide tailings samples and enough high gold extraction 60-82%.INTRODUCTIONIn Russia, as everywhere, there is a trend toward deterioration in the quality of mineral resources, including non-ferrous and precious metals, manifested in lower grade and higher complexity of ores. The proportion of refractory ores is increasing, characterized by fine dissemination of metals in sulfides, intergrowth, and poor liberation of minerals during concentration, resulting in loss of base and precious metals to flotation tailings.Over the operation period, huge reserves (hundreds of million tons) of ore processing waste have been accumulated at mining and concentration operations. Because of the imperfections of the previously used ore concentration technologies, the content of precious and base metals in flotation tailings is comparable with the grades of the ores being currently processed. Therefore, old tailings can be viewed as an additional reserve of non-ferrous and precious metals. The works (DEN, 1997; Lyman, Johnson, & Guerney, 2000) demonstrate that, tailings containing sulfides (sulfur, copper, zinc, and other metals) are a potential environmental hazard since they produce acid drainage water containing toxic components. Processing those tailings would require designing an effective technology for recovering useful components and protecting the environment."

Jan 1, 2016

By Helmut Ehnes

Over 330 million accidents at work happen world wide every year, only counting those leading to more than four days absence. More than 350,000 end fatal. Two million people more die every year due to work-related diseases. To sum this up: around 2.4 million people die every year because of work conditions. Among many risky industries, mining stands out. While mining represents just 1% of employees globally, it unfortunately represents 8% of all occupational fatalities. Mining operations go along with a variety of hazards. Not only in large operations, as they first come to mind, but also in the manifold small scale mines, with an estimated 13 million labourers worldwide exposed to substances such as dust, mercury and other chemicals, while also dealing with poor ventilation, inadequate space and overexertion. But is the number of severe accidents and diseases inevitable or can we change this situation? We can make mining sustainably safer, but we need a successful strategy to do so. A high potential lies in Vision Zero. Vision Zero is a prevention strategy for a safe future without fatal or serious occupational diseases, work accidents and traffic accidents. First defined as early as in the 19th century by Eleuthère Irénée du Pont, its very successful elements were adopted by many European countries first aiming at road safety, then extended to safety and health at work. Vision Zero?s holistic elements cover technology, workplaces, rules, and people as fields of action. By focussing on severe and fatal accidents, its application increases the level of safety and health overall.

Aug 1, 2013

By A. L. Field

Previous Publications THE first report on the slag viscosity work of the Bureau of Mines was made by one of the authors 1 in 1916. It was concerned chiefly with, the method of measurement. A paper 2 on this phase of the work was presented to the Institute in February, 1917, and a similar paper 3 was communicated to the Faraday Society. Purpose and Scope of the Slag Viscosity Tables Following the development of a suitable method, the next step in the investigation was the measurement of slag viscosity over a wide range of temperature and composition, and the arrangement of this experimental data in the form of tables for the use of the blast-furnace operator. It is believed that this information, if used intelligently, should help the operator to reduce losses in production caused by off-grade pig iron, to improve fuel economy, to promote operating efficiency, and to extend present-day practice to meet the increasing need of smelting lean and complex ores. In the experimental part of the work it was early observed that the temperature-viscosity relations of a slag were determined, for practical purposes, by the relative proportions of the three major constituents, lime (CaO), alumina (Al203), and silica (Si02), provided the percentage

Jan 12, 1917

By A. L. Field, P. H. Royster

The first report on the slag viscosity work of the Bureau of Mines was made by one of the authors1 in 1916. It was concerned chiefly with the method of measurement. A paper2 on this phase of the work was presented to the Institute in February, 1917, and a similar paper3 was communicated to the Faraday Society. PuRpose and Scope of the Slag Viscosity Tables Following the development of a suitable method, the next step in the investigation was the measurement of slag viscosity over a wide range of temperature and composition, and the arrangement of this experimental data in the form of tables for the use of the blast-furnace operator. It is believed that this information, if used intelligently, should help the operator to reduce losses in production caused by off-grade pig iron, to improve fuel economy, to promote operating efficiency, and to extend present-day practice to meet the increasing need of smelting lean and complex ores. In the experimental part of the work it was carly, observed that the temperature-viscosity relations of a slag were determined, for practical purposes, by the relative proportions of the three major constituents, lime (CaO), alumina (Al2O3), and silica (SiO2), provided the percentage

Jan 1, 1918

By Cadwallader Evans

THE American Institute of Mining Engineers was organized in the anthracite region of Pennsylvania by men who were primarily interested in anthracite. Its first meeting, at Wilkes-Barre, Pa., in the Northern Anthracite field, on May 16, 1871, resulted from a call sent out by three outstanding men of the anthracite .industry: Eckley B. Coxe, R. P. Rothwell, and Martin Coryell. The best known of these was Eckley B. Coxe, who was the manager of large hold¬ings operated by him and his family,. and who is remembered as the inventor of a special grate for burning very fine anthracite, known as the Coxe traveling grate, which is still very widely used. R. P. Rothwell was a well-known consulting engineer of the region, as was Martin Coryell, who was associated with another well-known anthracite family, the Pardees. There is no record of the discussions that resulted in this initial meeting, but it is safe to assume that the formation of the Institute was largely influenced, through appreciation by the founders, of the necessity for a free exchange of information covering the whole of the mining industry. One of the rules adopted at the first meeting was:

Jan 1, 1947

By Frank H. Riddle, Wilfrid R. Foster

GENERAL treatment of the various minerals of importance in refractories appears in the chapter entitled "Refractories" elsewhere in this volume. The present chapter is restricted to a discussion of minerals of the sillimanite group and brings up to date the excellent information contributed by Prof. Paul F. Kerr to the first edition (1937). Since the appearance of that edition, the status of the group has changed some- what. Kyanite remains the preferred source material for mullite refractories but total consumption of kyanite has increased considerably.85 The exigencies of World War II forced an increased dependence on domestic sources and led to an intensification of the search for higher-grade deposits of kyanite and allied minerals. The first discovery of massive kyanite similar to that of India has been reported from Georgia.37 British East Africa has joined India as a substantial supplier of our imported kyanite, but that from India continues to hold preference.85 During World War II, prices of both domestic and foreign grades reached peaks unparalleled since the earliest years of the use of kyanite and as yet have shown no tendency to return to prewar levels. Topaz, by virtue of the deposit outlined in South Carolina, merits inclusion in the group.20,36,95 Large andalusite deposits, which threaten to rival our one large domestic occurrence, have been found in Russia.69,88 Sillimanite has not yet attained an important position among these useful minerals because of the lack of accessible deposits of high-quality material in adequate supply.37,50,58 Tests by the Bureau of Mines have indicated the possibilities of economically beneficiating low-grade sillimanite and kyanite.105.106,140 Government, university, and industrial

Jan 1, 1949

By Henry H. Roos

NTRODUCTION In the mining industry, a "drill jumbo" is a drilling unit equipped with one or more rock drills and mounted on a mechanical conveyance. Jumbos range from single¬drill ring drills mounted on simple steel skids to sophisti¬cated multiple-drill units mounted on diesel engine powered carriers and equipped with automatic controls and sound-abatement cabs. Individual types of jumbos usually are designed for specific tasks such as fan drilling in sublevel caving operations. Some units, such as development jumbos, can be utilized for several functions in addition to their normal applications, e.g., for production drilling in room-and-pillar operations, stoping in cut-and-fill mining, etc. Mine operators can purchase individual components from manufacturers, assembling these components into a jumbo suitable for specific conditions. However, this requires that mine personnel have good engineering and mechanical abilities. Although manufacturers of jumbos maintain facilities for designing machines to meet con¬ditions created by new mining methods and unusual ap¬plications, the cost of the engineering and experimental work for new types of jumbos should be evaluated in terms of both costs and benefits; it may be advantageous to plan the mining operation so that existing and proven units can be utilized. GENERAL SELECTION CRITERIA Since the operating conditions vary in underground mines, the design of a jumbo must be selected to cope with the individual characteristics of the mine. The necessary considerations include access space into the working areas, grades expected to be encountered, radii of the curves, ambient temperatures, the characteristics of the rock, the acidity or alkalinity (pH rating) of the mine water, etc. Access to Mine Workings The mine workings must be accessible to the selected jumbo. Frequently, a jumbo must be disassembled at least partially to pass through the mine shafts. There¬fore, a bolted construction allowing disassembly into pieces of suitable size and weight is desirable in most applications. Type of Undercarriage Generally, a crawler-type undercarriage should not be used in trackless mines having acidic mine water. The acidic water causes an electrolytic action between the individual crawler parts and causes rapid corrosion and early failures. Propulsion A two-wheel drive on a pneumatic-tired jumbo is marginal for grades exceeding 12%. A four-wheel drive unit with good weight distribution is capable of operat¬ing on grades of up to 35%. At least 30% of the gross vehicle weight (GVW) should be carried on the steering axle; otherwise, the steering tires may not have sufficient traction on loose road surfaces and may "plow" instead of steer. To assure stable operation in mines with steep grades, the height of the center of gravity of the jumbo should be considered. It should not make the unit prone to rolling over on the steep grades that may be encoun¬tered. Turning Ability In confined working areas, a skid-steering or crawler unit has the best maneuverability. An articulated carrier is preferable when base-rotated parallel booms are being utilized. A rigid-frame jumbo with automotive steering is compact and economical, having lower maintenance requirements than the other two types. However, the turning radius of a rigid-frame unit is wider than either the skid-steering or articulated units, and this wider turning radius may be detrimental in mines with narrow drifts. JUMBO COMPONENTS Rail Undercarriages A mine with a rail-transportation system generally utilizes drill jumbos that are mounted on rail-type under¬carriages. With a light load and good weight distribu¬tion, this carrier may consist of a simple two-axle four-wheel platform onto which the boom-mounting brackets are attached. As the depth of the round and the penetration rates increase, the weight of the equip¬ment installed on the chassis also increases. The greatest problem with a heavy overhung load is balancing the carrier; a three-boom unit may require a substantial amount of counterweighting to maintain an acceptable 70% to 30% axle-load balance. Although lengthening the wheelbase helps balance the unit, a long wheelbase increases the turning radius, often creating problems on curves and sometimes requiring a swivel truck-type chassis. A good rule of thumb for a simple four-wheel undercarriage is to maintain a wheelbase length to track gage-width ratio that does not exceed 2.5 to 1.0. For a larger ratio, a swivel truck should be utilized. Swing-out outriggers or roof jacks help keep a jumbo in place during the drilling cycle. Usually, a rail-mounted jumbo is not self-propelled. Instead, it is maneuvered into place by a locomotive. Occasionally, several headings are being advanced in close proximity, and a self-propelled jumbo is con¬venient. In electrified mines, such a jumbo utilizes conventional battery-powered traction gear; in dieselized mines, hydrostatic drive components offer good flexi¬bility. The tractive power requirements of a typical rail jumbo may be calculated from the formula: HP = [(RR + GR) X Sl/[33,000 X Em X Eh]

Jan 1, 1982

By J. S. Heath

Many disputes related to environmental issues in mining are resolved through often-antagonistic negotiations in a regulatory context or through litigation. These approaches are certainly the best choices for resolving certain disputes. However, just as no single remediation technology is the right fit for every site, so no single dispute resolution process is the best choice for every situation. This paper introduces a range of dispute resolution alternatives (from collaborative decision making through mediation, arbitration, and litigation). Especially when money is tightest, cost-effective dispute resolution(and the outcomes that can accompany it) can have an impact on the bottom line.

Jan 1, 2000

Etching solutions containing hexavalent chromium ions (e.g., chromic acid) are used in brass finishing, printed circuit board etching, preparation of plastic for plating, anodizing, and various other industrial surface treatment operations. As the solutions are used, hexavalent chromium ions are reduced to their trivalent state, contaminants accumulate in the solution, and the effective acid concentration is reduced. When the etching rate becomes unsatisfactory for the particular operation, the solutions are discarded. This is a problem because the discarded solutions are pollutants, and because replacing the etching solution is expensive. The Bureau of Mines has developed a process for regenerating these spent solutions and returning them to the surface treatment operation without interrupting the etching process. An electrolysis cell containing anode and cathode compartments that are separated by permeable membranes, is used for regenerating the spent solutions. The spent chromic acid solution is fed to the anode compartment and sui (uric acid is circulated in the cathode compartment. Application of a steady electrical potential of a few volts dc across the electrodes causes the copper ions and other contaminants in the spent solution to migrate through the membrane to the cathode compartment where copper is plated onto the cathode. Zinc and the other contaminants remain in the sulfuric acid. At the same time, the complex, trivalent chromium ions in the spent solution are attracted to the anode where they are oxidized to their original hexavalent state. The regenerated solution in the anode compartment is then recycled back to the plant?s etching operation for reuse.

Jan 1, 1980

By J. J. Demo

The effect of aluminum additions on the coating vale and corrosion resistance of Cr-Fe diffusiou coalings on a mild steel substvate has been studied. Aluminum additions up to 2 wt pct increase the chromium penetration rate while further additions retard it. The apparent cor$lict between these data and metallogyapkic ineasurements, which show a continuially increasing coaling thickness with aluminum addition, is discrissed. Compavisorz of corrosion resistance on the basis of equal thickness of tlre entire coating measured mnetal- ALTHOUGH ferrous metal articles are cheap and widely used, they are often quickly degraded by corrosion. To prevent or slow down the corrosion process, lographically is misleading; equal thickness of the cor-rosion-resistant portion of the coating is a bette.v basis of conzpavison. Inter difision coefFicients for Cr-Al-Fe coatings of different aluminum content have been detevmined and found to dary logarithmically when plotted againnst chromium concentvation. A general method of calculating diffusion profiles for different lrealment limes and surfuce coucentralions IS described. many types of coating are applied to steel.&apos; Among these are diffusion coatings, formed by high-temperature diffusion of selected elements into the surface, which then becomes the coating Diffusion coatings are metallurgically bonded to the substrate and show a continuously varying concentration gradient from surface to substrate. Generally, these coatings have the advantage of adhering to the substrate upon deformation of the composite. Moreover, when chromium is one of the diffusion elements, a mild steel substrate

Jan 1, 1968

By Claudio Gutierrez

It has been claimed (Eadington and Rosser, 1969) that when freshly precipitated lead sulfide is in contact with oxygen-containing water, there is an "induction period" of at least a few hours during which no detectable oxidation of the lead sulfide takes place This effect would be of the utmost importance for the adsorption of xanthate on galena in flotation mills. It was tried here to reproduce the results obtained in (Eadington and Rosser, 1969), but no "induction period" was found. Besides, reasons are given to prove that the oxidation mechanism proposed by Eadington and Prosser (1969) is not realistic.

Jan 1, 1982

By Mary C. Nodine, Michael P. Walker, Paul Eggers, Donald E. Aubrecht

The CANALSIDE commercial development in Buffalo, New York serves to revitalize the former site of the Buffalo Memorial Auditorium, adjacent to Lake Erie. The Auditorium was constructed in 1940 and founded on steel H-piles driven to limestone bedrock. After decades of professional sport and entertainment events, the “Aud,” as it was locally known, was closed in 1996. It sat vacant until it was demolished in 2009, at which time plans were made to revitalize the area with shops, restaurants, and a historic replica canal. The only portion of the Aud that was left intact was a subbasement boiler room. The subbasement was renovated in 2014 and has since been used to house water and ice making equipment for the historic replica canals, which boast recreational ice skating in the winter. The subbasement floor was about 10 feet below groundwater and the Lake Erie water level. The floor consisted of an approximately 4-foot-thick layered inverted waffle slab system, with reinforced concrete grade beams and concrete infill between the grade beams. A waterproofing membrane was located near the base of the slab. There were no major seepage issues in the subbasement, so the existing waterproofing membrane was assumed to be intact and performing adequately. A four-story building housing a children’s museum was proposed to be constructed directly above the subbasement. The loads imparted by the new building would exceed the capacity of the existing piles, so it was determined that drilling micropiles through the subbasement floor would be the most practical means of supporting the new building. Drilling through the existing slab and waterproofing system was a concern due to the challenges of controlling water during construction and the importance of maintaining the integrity of the permanent waterproofing system.

Jan 1, 2018

By John V. Beall

Runding the bottom corner of the West Africa11 hump, one hovers off the coast of the tiny Republic of Liberia. But not for long-as Portuguese navigators, Blackbirders, and Farrell Line captains have learned. The ponderous swell of the Atlantic is driven by an on-shore wind that never dies. As remorseless as the Atlantic chewing away at the unbroken shoreline, is the country beyond-West Africa, where white meets black, where desert blends to bush to impenetrable jungle, where elephants chomp the foliage of young trees. This is a land from which the tsetse fly has driven the cattle, and the root crops grow big and voluptuous above the ground and are shrunken and barren of nutrient below. This is the environment of Liberia which is elbowing an iron ore market for itself on crowded shelves. Liberia is an anomaly in Africa. It was the first republic on the continent in modern times, having been established in 1848. While most of Africa was benefiting from the investment of foreign capital under colonial regimes, Liberia was going it alone. To be sure, Liberia was aware of foreign activity as hunks of territory were lopped off by neighboring French and English colonies. Today the country is about 43,000 sq miles, the size of Tennessee, which, in the language of exploration men, is a workable size unit.

Jan 12, 1962