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By Robert Livermore

It has been a noteworthy feature of the Cobalt camp, that many of the valuable ore deposits have been covered, wholly or in part, by small but usually deep lakes, such as Cobalt, Cart, and Peterson lakes, and with the subject of this article, Kerr lake. In the early days of the camp many water-covered areas, which have since been found to be valuable, were ignored or neglected by owners, or simply perfunctorily staked for water rights. Kerr lake is probably the evidence of a fault or sharp fold, having a general east and west strike, and containing a series of ore-bearing fissures, parallel generally to the strike, although having some notable exceptions to the general rule. On the north side of Kerr lake the formation is of diabase, while on the south side it is of Huronian slates and conglomerates. These Huronian measures extend out under the lake, dipping gently to the north to a lateral distance not yet definitely determined, owing to the lack of development under the deepest parts of the lake. Probably the contact between the diabase and Huronian or else between the former and the underlying Keewatin formation occurs somewhere near the center of the lake. Kerr lake originally covered 45 acres. Of this the Kerr Lake Mining CO. owned 12, the Drummond Mine, 7, and the Crown Reserve Mining CO. the remainder of 26 acres. Since the latter's property was originally entirely under water, it was necessary for the owners to make land for buildings and shaft room. Accordingly, in 1908, a trench was blasted out which deepened the outlet, and lowered the lake 8 ft. As many of the rich veins of the Crown Reserve and Kerr Lake companies were under water, mining was pursued under some disadvantages. Fortunately the rock is tight and solid, and mining has been done sufficiently fay from the surface to avoid unnecessary risk. Nevertheless, there was always danger of encountering open seams, through which too large a flow of water for comfortable working might come. Careful soundings were made over the veins, by means of steel-shod pipe, through mud and water to bedrock, but there was sometimes an element of uncertainty as to whether actual bedrock had been reached. Furthermore, the necessity of leaving safe backs between workings and lake tied up large quantities of ore, and made development in certain

Jan 1, 1915

By Peter V. Barr

Despite the advent of modem firing control systems reheating furnace operations frequently allow significant thermal excursions in the discharged slabs or billets after furnace delays. Although HSM furnaces are not immune to this and other related problems, mini-mill operations are most vulnerable due to their more frequent delays and (often) less sophisticated control systems. In order to reduce these problems control systems will commonly include a thermal model, operating either on-line (interacting directly with the controller logic) or in an advisory, off-line mode. Using a new 'fast' thermal model, the paper examines the thermal response of a typical mini-mill furnace during both delays and the subsequent recovery period. A variety of firing strategies are explored and compared on the basis of maintaining thermal excursions within allowable limits for rolling. Other factors, such as the potential for overheating of billets within the furnace during delays and the overall thermal state of the furnace, are also considered in some detail. Although common practice, the use of conventional thermocouple zone temperatures for furnace control during and after delays is shown to be a dubious proposition. Keywords: Reheat Furnace, Modeling, Process Control

Jan 1, 2003

By M. Al Mukhtar, D. Hoxha, X. Brunetaud, D. P. Do, C. Auvray, L. Michel

"Mechanical behavior of rock joints is often the key factor governing the response of complex structures constructed in fractured rock masses such as underground openings or of objects assembling various stones blocks such as historical building walls or damaged marble statues. This paper aims at developing a theoretical model to describe the behavior of fresh joints based on the description of their morphology. The main idea of the model is to establish a link between the effective contact surface of joints and the frictional coefficient. Beginning from a chosen level of joint surface description where a joint is considered as “smooth”, the model describes the added friction with respect to the increase of the contact surface of the joints and the distribution of stress in these contacts. The model developed initially for asperities with regular geometry is firstly compared with existing models and then applied on fresh artificial joints. For that, healthy artificial joints have been characterised using in one hand classical CNL shearing tests and in another hand the morphology of joints. The joints surfaces are digitized before testing using a high resolution laser scanner (Konica Minelota Vivid 910) allowing to obtain a precision up to 10µm. From these scanned surfaces the morphology of joints is characterised on the profiles running in the direction of shearing and a mean value of friction is calculated using the developed model. This calculated value is then compared with that obtained from CNL shearing test and a good approximation is notedINTRODUCTIONThe role of the mechanical behavior of rock joints on the overall response of fractured rock masses is well established in many fields of engineering activity going from the stability of underground constructions (Souley M, Hoxha D, Homand F 1999), rock slope stability (Einstein H.H. Veneziano D., Baecher GB., O’Reilly K.J, 1983, Jaeger 1971), various rehabilitation of masonry construction, damaged stone artworks restoration (Michel L., Do D.P, Coignard B, Hoxha, 2014) and so on. In the same time the characterisation of the behavior of joints and their modeling is nowadays a dynamic field of research or/and investigations and many alternative approaches have been proposed (Barton, N.R. and Choubey, V. 1977, Tatone, S.A. Bryan, Grasselli Giovanni 2010, William C E. 2007). While empirical relations of shear strength with various parameters of the joint morphology are the most used in practice because of their simplicity (Barton. and Choubey, 1977, Barton 1973, Bandis S., Lumsden A. C. and Barton N. R. 1983) many other models of joint strength are developed based on mechanistic considerations (Haberfield CM, Johnston IW. 1994), multiscale approaches (Yang Z.Y., Di C.C., Yen K.C. 2001, Fardin N., O. Stephansson, Lanru Jing 2001) or micromechanical ones (A. Serrano, C. Olalla, R.A. Galindo 2014) to mention just a few of research trends on rock joints modeling."

Jan 1, 2015

By C. E. Golson

Modern concrete technology emphasizes the basic qualities required of an acceptable aggregate: it must be clean, sound, homogeneous, and of a size gradation resulting in a concrete of the desired physical qualities at a minimum cost. In the case of coarse aggregates, crushing, scrubbing, and screening will usually provide the required material, although beneficiation is often necessary in order to eliminate unsound or deleterious fractions. Beneficiation is also applicable to fine aggregates,( but the processes most often employed are washing, classification, and dewatering.

Jan 1, 1959

By William O. Macha G

El presente trabajo describe la molienda y flotación como etapas de mejoramiento en la metalurgia del plomo en Paragasha. Para ello, se revisa los principales problemas de la metalurgia, como el de los minerales encontrados en la superficie, entre otros. Asimismo se describen los circuitos pertinentes de la planta piloto, como de la planta Paragasha y los resultados metalúrgicos en los meses de enero a marzo en 1965. En el primero, se señalan las dos etapas de molienda y flotación en el Pb, mientras que en el segundo, se muestra el circuito stándard: molienda y flotación.

Aug 20, 1965

By Carlos Bruno Eckstein, Gabriela Ribeiro Pereira, Luís Henrique de Almeida, Clara Johanna Pacheco, Mónica Patrícia Arenas, Mariana Gaudencio B. Lima, Ana Beatriz Fonseca, Laudemiro Nogueira Júnior

Neste trabalho foi caracterizada a influência da evolução microestrutural e da composição química de aços austeníticos HP-Nb na resposta magnética detectada pela técnica de microscopia de força magnética (MFM). Além disso, também foi determinada a influência das forças eletrostáticas no sinal detectado por tal método, através da implementação da técnica de microscopia por força Kelvin (KPFM). Para este estudo, foram analisadas quatro amostras, que foram extraídas de dois tubos de reforma a vapor com diferentes composições químicas. Cada uma das amostras estudadas foi extraída de uma região do tubo exposta a diferentes temperaturas resultando em distintos estados de evolução microestrutural. Segundo os resultados obtidos, apenas as amostras com estado de envelhecimento I exibiram resposta magnética nas interfaces matriz-carbetos.

Oct 28, 2019

The phenomenon of Instantaneous Outbursts, although not new to Australia, was sharply drawn to the attention of the local coal-mining industry by two isolated fatal occurrences on widely separated fields, both late in 1954. An outburst is the eruption of apparently solid coal from the face, aided by vast quantities of gas released from the coal, as the coal fails under mining stresses additional to its natural stressing.The gases involved are principally methane and carbon dioxide. The various factors which combine to produce outburst conditions range from external factors such as stresses arising from depth of cover and other causes, to inherent factors such as strength of coal,and its capacity to retain gases (sorption). Of the localities where instantaneous outbursts occur the Gard Basin in Southern France has had the greatest number and the most serious occurrences. By contrast, local outbursts have been minor.Experimental work into some influencing factors has been carried out by various overseas authorities and some research has been accomplished in Australia. Practices used in some overseas areas to improve safety of working are largely empirical, as are the local rules and recommendations for work in affected areas.The appearance of further outburst areas is anticipated as mining becomes more extensive and deeper.INTRODUCTION"Instantaneous Outbursts" can be described as violent eruptions of coal from the solid accompanied by considerable gas evolution. The projected coal is usually of small size, and a high proportion is pulverized, and may be carried and deposited over great distances by the gases, liberated from the outburst. This outburst coal is of bituminous to anthracitic rank, and the gas involved is essentially methane or carbon dioxide, or a mixture of both. Outbursts involving carbon dioxide are usually more violent and dangerous. The phenomenon is relatively unusual, being confined to probably sixteen known areas in the entire world, these areas comprising only portion of the coalfields in which they occur. Usually only one or two mines on each field are affected.

Jan 1, 1958

By R. E. Wade

The Butte, Anaconda & Pacific electrification is of peculiar interest, in an incidental way, to the entire mining fraternity, and especially the engineering branch, not only in this great Northwest country but throughout the entire Western mining country, which is rich in minerals and water power. It is probably fair to say that the prime object of mining and smelting engineering is to reduce the cost of production, and in the case in hand the relative location of mines and smelter brings the cost of transportation of ore to the front. While some might assign this item to the railway people, it is inseparably a part and parcel of the general scheme of the production of metal from the ore. In considering the electrification of the B., A. & P. railway the mining and smelting engineer, above all, wants to know what saving will be effected by the change in motive power. Unfortunately the new power has been in use during a very limited period and on the Smelter Hill section of the road only, and no reliable data, from actual service conditions, can be obtained until the entire electrified section has been in service for a reasonable length of time. Any remarks on this subject at the present time, therefore, must of necessity be general in nature and more or less descriptive. The railway, electrical and mining worlds and the country in general are indebted to the B., A. & P. railway for the pioneer work it is now doing, as it undoubtedly marks the beginning of the electrification, within the comparatively near future, of all transcontinental roads between the Missouri river and the Pacific coast. Together with this goes the development of an untold wealth in water power and all natural resources within the same territory. For the first time in the history of electric railway work, in this country, direct current at a potential of 2,400 volts is being used. With this potential there is a great saving in transmission of energy to the locomotives and there are only two substations, one at either end and 26 miles apart, for supplying the power for the movement of trains of heavy tonnage over the main line and for switching movements at terminal and intermediate yards, and comparatively little feeder copper is required.

Jan 1, 1914

By Chris Mark

Perhaps the most significant development in coal mine ground control during the last century was the introduction of roof bolting during the late 1940's and 1950's. From an engineering standpoint, roof bolts are inherently more effective than the wood timbers they replaced. Roof bolts promised to dramatically reduce the number of roof fall accidents, which then claimed hundreds of lives each year, and they were initially hailed as "one of the great social advances of our time." Roof bolting also emerged at a time of rapid technologic transformation of the coal industry, and greatly accelerated the transition to trackless, rubber-tired face haulage. The U.S. Bureau of Mines quickly became the new roof support's strongest advocate. Some state agencies and miners were skeptical at first, but nearly everyone was soon won over. Case histories were reported showing that roof falls could be largely eliminated while productivity increased dramatically. Little wonder that, in the words of one contemporary observer, "roof bolting has been adopted more rapidly than any other new technology in the history of coal mine mechanization." Yet by the end of the 1950's, it was clear that roof fall fatality incidence rates had actually increased. It would be another decade before the superior ground support provided by roof bolts would clearly save lives, The story of how roof bolting was implemented by the mining industry, but took so long to live up to its promise, is a fascinating example of the interaction between economics, technology, regulation, and science. It still has important lessons for today.

Jan 1, 2002

By K. B. Chaudhurl

The thermodynamics of the reactions taking place are examined with the aid of equilibrium diagrams for the Pb-O-S system. Based on investigations of chemical, mineralogical and differential-thermo analyses of intermediate products of different desulphuration degrees, an attempt is made to explain the mechanisms of the reactions in the smelting shaft of the KIVCET furnace. The differences between this and other direct lead smelting processes are demonstrated by these thermodynamic and kinetic considerations. Proceeding from these results, the practicability of direct lead smelting processes is discussed with reference to the composition of the primary feed materials to be processed. This comparison also considers the behaviour of minor metals, the products obtained and their characteristics in respect to further treatment. For assessing the operating costs, the over-all energy consumption is considered taking into account various price relations between electric energy and fuels/reductants. Based on the peculiarities of the various processes, an attempt is made to compare the necessary means of meeting the pollution control requirements. The paper concludes with reference to the criteria and problems involved in comparable evaluations.

Jan 1, 1978

By R. E. Wade

THE Butte, Anaconda & Pacific electrification is of peculiar interest, in an incidental way, to the entire mining fraternity, and especially the engineering branch, not only in this great Northwest country but throughout the entire Western mining country, which is rich in minerals and water power. It is probably fair to say that the prime object of mining and smelting engineering is to reduce the cost of production, and in the case in hand the relative location of mines and smelter brings the cost of transportation of ore to the front. While some might assign this item to the railway people, it is inseparably a part and parcel of the general scheme of the production of metal from the ore. In considering the electrification of the B., A. &. P. railway the mining and smelting engineer, above all, wants to know what saving will be effected by the change in motive power. Unfortunately the new power has been in use during a very limited period and on the Smelter Hill section of the road only, and no reliable data, from actual service conditions, can be obtained until the entire electrified section has been in service for a reasonable length of time. Any remarks on this subject at the present time, therefore, must of necessity be general in nature and more or less descriptive. The railway, electrical and mining worlds and the country in general are indebted to the B., A. & P. railway for the pioneer work it is now doing, as it undoubtedly marks the beginning of the electrification, within the comparatively near future, of all transcontinental roads between the Missouri river and the Pacific coast. Together with this goes the development of an untold wealth in water power and all natural resources within the same territory. For the first time in the history of electric railway work, in this country, direct current at a potential of 2,400 volts is being used. With this potential there is a great saving in transmission of energy to the locomotives and there are only two substations, one at. either end and 26 miles apart, for supplying the power for the movement of trains of heavy tonnage over the main line and for switching movements at terminal and intermediate yards, and comparatively little feeder copper is required.

Jan 11, 1913

By L. D. van Dyk, G. S. Tshofu

Iron ore fines are by-products of iron ore mining operations. Unlike iron ore lumps, fines cannot directly be used in conventional iron making processes, and consequently large quantities accumulate around the world. Pelletizing and sintering can be used to convert iron ore fines into agglomerates or briquettes for processing with lump ore, but these techniques are energy intensive and produce greenhouse gases. This research investigated the extraction of iron from iron ore fines using acetylacetone (a ß-diketone) as an environmentally friendly alternative process for fines utilization. A 2k factorial experiment design was used to identify the significant extraction variables. It was found that the reaction temperature and solid to liquid ratio had significant effects on the extraction process. The extraction kinetics were studied at different temperatures and the highest iron extraction (97 %) was obtained after 48 hours at 413 K and 0.025:1 (g:mL) solid to liquid ratio for a particle size range of +106 to -150 µm. The extraction products were easily separated from the unreacted acetylacetone by flash distillation and iron(III) acetylacetonate crystals were recovered. An economic evaluation showed that selling the crystals was profitable. Alternatively, the crystals can be reduced with hydrogen to iron particles and acetylacetone (for reuse).

Jan 1, 2015

By Vitor de Oliveira Campos

Vários resíduos gerados nos processo siderúrgico são fonte de ferro e podem ser reciclados e reintegrados de volta ao ciclo produtivo do ferro. Exemplos incluem pós de coletores e despoeiramento, carepas e lamas. Estes materiais são geralmente classificados como rejeitos e são descartados em aterros a um alto custo, mas adquirem um valor significante quando reciclados e reutilizados apropriadamente. O presente estudo consiste em demostrar a viabilidade da utilização destes resíduos em um processo de mini sinterização, plantas de sinterização produzindo até 1 milhão de toneladas por ano. O produto obtido apresenta propriedades químicas e físicas adequadas para carregamento direto no alto-forno, para utilização como nucleante na sinterização, ou como refrigerante no convertedor. O balanço do zinco e dos álcalis é de extrema importância para viabilizar um sínter final com qualidade requerida e será analisado neste estudo. Conclui-se que a utilização dos resíduos citados é economicamente viável e o estudo de caso apresentado neste trabalho comprova o benefício com retorno significativo.

Aug 1, 2018

By Ahmet Haxhiaj, Jaroslaw Drelich

"Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepçë is done at about 9000C, for pellets which are composed of PbS, CaCO3, Fe2O3, and SiO2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO2, and FeO, and porosity. The plant’s practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.IntroductionAgglomeration roasting of sulfide lead concentrate is an important phase in the production of lead by reductive melting [1-6]. The reductive melting process is a complex process with contradictory effects of several technological indexes which many times are hard to measure and determine. In this process, loading the water-jacket furnace with pellets of optimized composition and structure can reduce the consumption of coke, and achieve high level of lead recovery. Pellets (agglomerates) should be porous, but at the same time they should have necessary mechanical strength. ‘Self-melting’ ability of pellets is controlled by the types and quantities of fluxes blended into the pellet composition. Three major additives and their role are:"

Jan 1, 2011

By Manuel Gomez

Primary, low-temperature tars are generally known to alter with time. The effect is believed to occur, in some instances, without the external influence of air, light, or heat. Since one of the processes occurring during extended storage is oxidation, the action of mild oxidation induced by air and heat, in addition to the effect of storage, was studied. The principal effect in aging and oxidation is formation of pitch at the expense of the distillate fraction. The fraction boiling above 270° C. is mainly involved in pitch formation due to storage, whereas all fractions are affected to some degree when tar is heated at 125° C. in the presence of air. If the effects of air are considered, the aromatic and tar-acid fractions seem to be important in pitch formation.

Jan 1, 1956

By Thiemo Hagedorn, Gerhard Weissbach, Ralph Bergmann, Wilhelm J. Kogelmann

The objective of this unique method is to multiply the advance rate of conventional tunneling while improving both ground control and the safety of the crew. The high advance rate is achieved by concurrent rock excavation and installation of concrete lining at fully synchronized work phases. The novel TACHUSMATIC system consists of a high-production, robotic cutter boom, an automated slip form and continuous mucking and conveying. This novel system utilizes the inherent bearing capacity of the rock that is activated by a small, initial deformation. The supporting resistance is then provided both by the rock mass itself and the pumped in concrete lining. During the hardening of the concrete, the hydraulic cylinders of the TACHUSMATIC automatically apply the appropriate support resistance, thus providing safe ground control. This novel tunneling system is practically a fully automated, fail-safe NATM that does not require highly skilled engineers and crew. The TACHUSMATIC can be used for construction of circular, rectangular and horseshoe-shaped tunnels. When equipped with the Alpine Multi-Tool Miner (MTM) systems, the machine can work in a wide range of ground and rock conditions. The use of novel, diamond-tipped cutter bits (picks) will increase hard rock cutting capabilities and will significantly reduce pick consumption. Because of its moderate cost, the novel system is an economic alternative to conventional tunneling even at short drivages. A new installation is cost-effective for tunnels longer than 750 meters (2,500 ft.) At a typical tunneling project, the cost permeter is about 25% lower than with conventional methods.

Jan 1, 2003

By Ana Carolina Martins Silva

Os aços inoxidáveis dúplex ferríticos-austeníticos fazem parte de uma classe de materiais com microestrutura bifásica, composta por uma matriz ferrítica e ilhas de austenita, com frações volumétricas aproximadamente iguais dessas fases. Essa classe de materiais é caracterizada por apresentar interessante combinação de elevadas propriedades mecânicas e de resistência à corrosão e, por isso, é considerada bastante versátil, sendo utilizados nas indústrias química e petroquímica, de papel e celulose, siderúrgicas, alimentícias e de geração de energia. Este trabalho objetiva caracterizar as microestruturas do Aço Inoxidável Duplex SAF 2205, revelando as fases que se apresentam após tratamento térmico a 800ºC, em diferentes tempos, estudar a relação entre a dureza do material e a precipitação da fase sigma, além de determinar a cinética de precipitação dessa fase. Após obtidos os dados experimentais, dados de VV e composição de equilíbrio da fase sigma foram obtidos via Thermo-Calc. Ao final do trabalho, os resultados experimentais e de simulação são comparados e conclui-se que a nucleação da fase sigma é por difusão de Cromo na matriz.

Oct 30, 2017

By J. Botula

In the region of the North-Bohemian Coal Basin and its environment, there, in a row of places, are found the accumulations of rocks of the sedimentary and pyro clastic origin, the preliminary composition of those shows the possibility of their being utilized for the production of ecologically sparing natural Fe- and Ti- pigments and filling substances. In many places of the regions of Chomutov and Podborany and near Bilina and also in other places, there are found raw stocks perspective for the preparation of yellow up to ochre-brown, red, brown-red and green dyes. The target of project is the verification of dispensable reserves, their mineralogical composition and chemical and physical attributes, verification of treatment ways of Fe-and Ti-pigments separation (hydrocyclones, magnetic and electrostatic separation) and their stabilization and technological painting attributes for applications in colors, coating and plastic masses, mortar mixtures etc.

Jan 1, 2014

By Francis Church Lincoln

I. SITUATION AND SURROUNDINGS. THE Promontorio mine is situated at the northern end of the Sierra San Francisco de Coneto, in the town of Promontorio, Partido of El Oro, State of Durango, Mexico. As shown in the sketch-map, Fig. 1, the nearest railroad station is Chinacates on the Mexican International Railroad, 82 miles north of the city of Durango. The mine is 16 miles north of the station by air-line. It is reached by means of a good wagon-road which first crosses the Guatimapé Plain, passing the ranches of San Antonio and San Julian, to Estacion-a distance of about 15.5 miles-and then entering the mountains crosses the Sierra to Promontorio-a further distance of 11.5 miles¬making in all a distance of 27 miles by road from railroad to mine. Promontorio is just beyond the summit of the range, at an elevation of about 8,000 ft. above sea-level, or 1,350 ft. above the Chinacates station. The Castillo de San Francisco, the highest peak in the Sierra, has an altitude of 10,000 ft., and the Promontorio road crosses the summit of the ridge at an elevation of 9,000 ft. by a pass just below this peak known as the Puerto del Almagre. The Promontorio mill is situated at Santa Ives, 2 miles by tram or 3 miles by wagon-road to the north of Promontorio and about 600 ft. lower. The Sierra San Francisco de Coneto decreases in height towards the north and west till it comes to an end at the Melchor Arroyo on the ranches of Melchor and Ramos. Beyond this arroyo another range, the Sierra de la Candela, begins. In the vicinity of the Promontorio mine the hills are very rugged and the surface is furrowed by ravines which contain running streams during the rainy season-July, August and

Jan 1, 1908

By G. C. Naveen

Punatsangchu Hydroelectric Project Authority is constructing 1020 MW underground hydroelectric project in Bhutan. The project envisages construction of concrete dam, Desilting Chamber, Head Race Tunnel, Power House Complex and Tail Race Tunnel. Tunneling is one of the major activity in any underground projects as they are driven for multiple activities. By and large the tunnels are a major part of connecting networks from surface to caverns/underground working sites. Many tunnels in hydropower project are part of water conducting systems and one such important tunnel is the Tail Race Tunnel in this project and had to be excavated in thinly foliated rockmass conditions by D&B method. The rockmass is traversed by three to four joint sets and few minor shear seams. Rock Class “Q” values were between III and IV. Tunnel was excavated by full face parallel hole drilling blasting method. The adopted blasting method consisted of drilling 45mm (1.77 inch) diameter holes to a depth of 2m and the drilled holes were charged with 40mm (1.57 inch) diameter cartridge explosives and charges were initiated with half second non electric initiators. The perimeter holes were drilled at closer spacing of 30cm (1 feet) and alternate holes were charged using 32mm (1.23 inch) diameter cartridges explosive. Low dipping foliation joints present in the rockmass tend to slab in crown portion and erratic occurrence of intrusive bodies lead to unpredictable behavior of rock mass posing a major challenge for the safe excavation. Stability was a major issue through controlled blasting under constant supervision too could not limit the overbreak in certain weak rockmass conditions thereby exposing cavities of about 2.5m (8.2 feet). The stabilization of these cavities and handling the overbreak due to rockmass condition was time consuming and warranted additional supports. With systematic measurements and controlled blast designs the Horse Shoe Shaped Tail Race Tunnel of 9.1 m (29.85 feet) diameter and 304m (997.37 feet) length to connect with Downstream Surge Gallery of 314m (1030 feet) length, 18m (59 feet) wide and 58.8m (193 feet) height in thinly foliated and jointed biotite gneiss rockmass was successfully excavated.