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By Edwin K. Maughan

The Rocky Mountain region contains part of the paleocontinental shelf that lay in Arizona and New Mexico through Utah, Colorado, and Wyoming into Montana and North Dakota. The shelf was bounded by the northeast-southwest-trending Transcontinental arch and the Cordilleran miogeocline in late Paleozoic and early Mesozoic time. Major tectonic features that affected middle Phanerozoic sediments on the shelf were the Big Snowy trough and Williston basin in the north and the ancestral Rocky Mountains in the central part of the region. The Zuni uplift and similar positive areas occurred along the axis of the Transcontinental arch in the southern part. The late Paleozoic and early Mesozoic sedimentary rocks record transgressive-regressive marine cycles in which the Cordilleran shelf and much of the adjacent craton were inundated by epeiric seas. Early in the Carboniferous, an epeiric sea covered most of the shelf. Greater topographic relief developed in Late Mississippian, was at a maximum in Middle Pennsylvanian, and then diminished through Permian and Triassic time. The development in the Pennsylvanian Period of horsts and grabens along northwest- trending faults on the northwest flank of the Transcontinental arch resulted in the ancestral Rocky Mountain system. The eastern part of the region was emergent by Middle Triassic, and the emergence lasted until Middle Jurassic, owing to uplift along the Transcontinental arch. During the early part of the Mesozoic, the sediments were dominantly terrigenous and were deposited mostly in shallow littoral marine environments shifting to continental. Most middle Phanerozoic structural elements within the area of the shelf are characterized by lineaments that have either an east-northeast or a conjugate north-northwest trend. The east-northeast lineaments closely parallel the northeast trend of the continental slope (miogeocline) in Nevada to southern Idaho. The conjugate set closely parallels the northwesterly continuation of the miogeocline north of an approximately right- angle bend in south-central Idaho. The northeasterly trending Transcontinental arch and the northwest-trending margin of the Canadian Shield are parallel structural elements with the north- east and northwest trends of the miogeocline. The rectangular lineament pattern on the shelf suggests a system of rectilinear fractures within the underlying Precambrian crystalline basement rocks that moved several times in the Phanerozoic in response to external forces applied against the continental crust. Movement of these blocks influenced erosion, deposition, and lithofacies of the sediments in middle Phanerozoic time. Zones of crustal weakness, represented by the lineaments bounding these blocks, probably were influential in localizing sedimentary mineral accumulations and petroleum deposits, as well as later igneous intrusions, volcanism, and emplacement of hydrothermal ores. Igneous activity in this region was rare during the middle Phanerozoic, but these conjugate fractures seem to have been avenues for later passage of hydrothermal solutions responsible for ore emplacement.

Jan 1, 2013

"The sulphide nickel resources of Australia are concentrated in the Western Australian Shield. This shield is considered to have developed by extensive, but incomplete, Proterozoic reworking of once-continuous Archaean crust. It now constitutes relic Archaean cratons and intervening orogenic mobile belts transected by narrow, curvilinear tectono-thermal mobile belts of younger Proterozoic age. Remnants of the Archaean cratons are exposed in the Yilgarn and Pilbara Blocks. In the former an ancient (to ca 3600 m.y.) high-grade gneiss terrain (Western Gneiss Terrain) occurs along the western margin of the block and is interpreted to flank younger (ca3000-2800 m.y.) greenstone belts to the east. Ancient (to ca3500 m.y.) granitoid-greenstone terrains dominate the Pilbara Block.Proterozoic mobile belts contain only traces of nickel mineralization, except for one locality in the Halls Creek Province. The Archaean high-grade gneiss terrains contain no important mineralization, and the Pilbara granitoid-greenstone terrains contain only scattered examples of less important types of mineralization.The important deposits (e.g. Kambalda, Windarra, Agnew, Mt Keith) are all of komatiitic affinity and are best developed in the youngest greenstone belts of the eastern part of the Yilgarn Block. In particular, they are concentrated within, and adjacent to, the Norseman-Wiluna Belt, which contrasts in age, lithofacies and structural style with all other greenstone belts in the shield. It is interpreted to have been a rift zone. Within this belt the two main deposit types—the volcanic peridotite-associated and intrusive dunite-associated deposits—are concentrated into spatially separate zones. Precise controls on this heterogeneous distribution cannot be determined unequivocally from available data. One possibility is that the major volcanic peridotite-associated deposits were developed selectively in the actively subsiding axial part of the rift zone during the early extensional phase, whereas intrusive dunite-associated deposits were formed during a subsequent (less active?) stage of volcanic basin development. Distinctive sub-types (facies) of the volcanic peridotite-associated deposits form clusters that are generally within the rift zone. These may represent deposits related to discrete eruption centres, and at least part of their variation is due to relative position within extensive, topographically confined, linear flows."

Jan 1, 1984

By Boorder De, B. S. Panov, A. B. Westerhof, V. A. Korcemagin

Paper presented at the conference on Economic geology in Europe and beyond II, models for <mineral deposits> in sedimentary <basins>, held in Keyworth, UK, 13-14 April 1994. The Hg and Sb deposits of the Mediterranean and Circum-Pacific Belts are often found at elevated structural levels, suggesting that their preferential occurrence in young orogenic belts is not a fundamental metallogenic feature but merely reflects their chances of surviving post-orogenic peneplanation. In western Europe their emplacement appears often to be related to late orogenic extensional events accompanied by a notable increase in heat flow. Although Nikitovka and Almaden have quite different settings, both appear to be related to deep-reaching shears. Together with brittle fault zones at higher levels, these provided pathways for fluid phases that originated at least partially within the mantle. The Nikitovka deposits are located in the Donets segment of the 2 000 km Pripyat-Dniepr-Donets palaeorift in the East European Platform. Initiated in the mid-Devonian with a possible Precambrian precursor, its listric boundary faults displace the Moho from a depth of about 50 km north and south of the rift to 35 km along the axes of the Pripyat and Dniepr segments. The steep central anticline of the Donets segment, within which the main Hg-Sb district is located, is interpreted to be associated with a reactivated fault reaching into the upper mantle. The Almaden syncline, formed during the Variscan Orogeny, may be an older pull-apart basin or half-graben associated with the collapse of the Cadomian Orogenic Belt. It is situated on a major ENE-WSW-striking shear zone which may represent a Late Cadomian transfer zone reaching into the mantle

Apr 1, 1995

By D Craw, P Upton

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Otago Schist belt of southern New Zealand hosts widespread orogenic gold deposits. Erosion of these orogenic gold deposits has led to the formation of numerous placer deposits distributed across and beyond the host schist belt. Numerical modelling of crustal scale deformation and geomorphic evolution has defined the key tectonic features that have controlled the severance of detrital gold deposits from their sources. Tectonic activity over the past 20 million years, during development of the modern Pacific-Australian plate boundary, has severed links between some placers and their sources. Detrital gold was transported south from the Otago Schist source region in two different river systems in the Miocene. Mesozoic orogenic gold deposits shed gold into rivers that flowed to the south. These rivers were terminated by the rise of north-west-trending basement ridges at the boundary between weak schist crust and strong greywacke crust, and the ridges were controlled by pre-existing faults at that rheological boundary. In contrast, rising mountains close to the developing plate boundary in the Miocene were the locus of new orogenic gold deposits hosted in extensional faults. These gold deposits were rapidly exhumed and contributed detrital gold to orogen-parallel Miocene rivers that flowed to the south-west. Pleistocene deformation on mainly north-west and north-east orientations, and associated river capture, has severed the links between these Miocene orogenic deposits and downstream detrital gold.CITATION:Craw, D and Upton, P, 2015. Tectonic severance of links between placer gold and its sources, southern New Zealand , in Proceedings PACRIM 2015 Congress, pp 541–544 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Chen Lin

Tectonic stress is an important parameter for understanding the dynamics of underground engineering and for the exploitation of coalbed methane. Multiple-period structural features usually have complex spatial relationships in tectonic superposition areas, which provides evidence for identification of the sequence of the tectonic stress period. Conjugated joints and slickensides are used to reconstruct the tectonic stress of the No. 8 Mine in Pingdingshan. Based on the geological unit division and field measurements, data on hundreds of joints and slickensides are collected from 33 stations. The tectonic stress results indicated by the conjugated joints show that there are mainly four directions of tectonic stress: NEE-SWW, NW-SE, NE-SW, and NNESSW. The tectonic stress results of the slickensides indicate that there are mainly four directions of tectonic stress: NNE-SSW, NNW-SSE, NEE-SWW, and NW-SE. According to the systematic analysis of the joints and slickensides, this paper separates the superposed joint and slickenside sets and identifies the tectonic stress periods with their abutting relationships. Three tectonic stress periods are determined and the sequence of the tectonic stress periods is NE-SW, NW-SE, and NEE-SWW. The results are consistent with other tectonic stress measurements for both the region and the locality.

China has been producing gold for more than 4000 years with gold production increasing substantially since the 1980s, from about 25 tonnes in 1980 to some 160 tonnes in 1998. More than 80 per cent of the gold production is from East China. However, complete information on eastern China gold has been rarely reported internationally. This is a general overview on the tectonics and metallogeny of gold deposits in East China. The geology of these gold deposits is compiled mainly from data and information reported in China, and is also based on the authorÆs work in China from 1974 to 1986 and a recent visit to China.

Jan 1, 1999

The New Guinea Mobile Belt is the northern zone of the Melanesian Orogeny (Dow and Sukamto, 1984), which consists of a complex zone ofupthrusted and accreted, regionally metamorphosed geosynclinal sediments and volcanics of Mesozoic to Eocene age and the overlying sediments. On the northern margin of this accreted terrane, formed an Eocene to Middle Miocene island arc. The North New Guinea Basin formed during the Upper Oligocene on the accreted margin. The depositional history of this basin is complicated by major crustal movements during the Upper Miocene to Holocene. During the Middle to Upper Miocene two magmatic arcs were emplaced. The northern magmatic arc is in part, spatically and genetically related to the Eocene to Middle Miocene island arc. The Maramuni-Utawa Magmatic Arc (southern) is a result of the Oligocene accretion and regional metamorphism. Coincident witt these magmatic arcs are belts of mineralization containing porphyry Cu-Au, epithermal/hydrothermal Au, Ag + Cu-Pb-Zn, exhalative Cu-Pb-Zn + Ag-Au, lateritic Ni-Cr-Co + PGE and alluvial Au, PGE, Cr occurrences and deposits. An intergrated tectonic model is presented for these and other data for the northern zone of the Melanesian Orogeny.

Jan 1, 1990

Four data sets are required to put constraints on the tectonic evolution of the southern rim of the Pacific Ocean basinI . data bearing on the dispersal of the major Gondwanaland continental fragments and the birth of the Southern Ocean,2. data bearing on the interaction of the Pacific Ocean basin lithosphere with the South American, Antarctic, and Australasian continental masses,3. data bearing on.the evolution of the Scotia Sea floor, and 4. data bearing on the evolution of the various continents, microcontinents. and volcanic arcs.

Jan 1, 1990

Deformation of the lithosphere by tectonic forces is investigated from both observational and theoretical standpoints. Global and regional geophysical data bases, coupled with the means for their rapid display and analysis, facilitate recognition of areas of the con- tinents and oceans where the response of the lithosphere to these deforming processes might fruitfully be studied. Gravity anomalies, from Seasat altimeter data and from land and shipboard measurements, provide critical infor- mation on the isostatic state of deformed lithosphere and therefore on its thermal and mechanical properties.

Jan 1, 1987

Forty two new apatite and zircon fission track analyses on the Kubor-Marum-Bena Bena area of northern Papua New Guinea severely constrain the timing of tectonic events and hence the tectonic models for New Guinea, particularly arc-continent collision. In addition, the data can be analysed regionally in terms of known and assumed lithospheric fault zones inferred to control mineralisation (eg. Corbett 1994; Kendrick et al 1995; Hill et al 1996) to determine reactivation of these zones. When combined with the new kinematic plate models for the evolution of New Guinea (Hall 1997) there is the potential to predict likely zones of mineralisation. The low-medium grade? Palaeozoic rocks of the Bena Bena terrane yielded a zircon fission track age of 17 Ma, indicating the time of cooling below 200¦C. The age is consistent with `the shift, at about 16-18 Ma, from volcanolithic sediments to mixed provenance sediments rich in quartz and metasedimentary lithic fragments in the southern Finisterre Ranges (Abbott et al. 1994). This shift was recorded in the Sukurum Formation, which ranges in age from Middle Miocene to Pliocene with quartzose and metasedimentary grains in all samples. Although recording rocks at temperatures of 200¦C and hence depths of ---5km, the 17 Ma age suggests the Bena Dena terrane was rapidly cooling at that time due to uplift and erosion, supplying metasediments to the southern flank of the Finisterre Range, currently 100 km to the east. Significantly, the Middle Miocene Akuna Intrusive Complex, dated 14-17 Ma by Page (1976), lies almost entirely within or adjacent to the Bena Bena terrane. Potentially the uplift, erosion and cooling of the terrane at 17 Ma may have been caused by the rising plutons. If so the 800 sq km exposure Akuna Intrusive Complex at the SE end of the Bena Bena terrane may have been the focus of uplift and supplied the metasedimentary detritus to the Finisterre Range. This suggests that the Finisterre Range was not far removed from the Bena Bena terrane, perhaps less than the 200 - 400 km indicated by Abbott et al (1984). The Akuna Intrusive Complex probably resulted from subduction of the Solomon Sea Plate beneath the PNG margin. In order for the subducted slab to reach depths of -100km below the area to facilitate partial melting and plutonism (Hamilton 1994), subduction probably commenced 3-5 Ma Ma before plutonism, ie at or prior to 20 Ma suggesting a significant change in the tectonic regime at -20 Ma, perhaps related to collision of the Solomons - Ontong Java Plateau collision (eg. Hall 1997). The main result to emerge from the 28 apatite fission track analyses is that the whole of the study area underwent rapid cooling due to uplift and denudation in the Late Miocene, mainly between 7-10 Ma. Results from several samples indicate that they were not totally overprinted prior to uplift indicating maximum burial of -3 km in the Middle Miocene, assuming normal temperature gradients. The burial is less if higher gradients are assumed, allowing for Middle Miocene plutonism. The Late Miocene cooling in the Mobile Belt agrees well with the Pliocene to Recent cooling in the Fold Belt to the SW, interpreted to be due to uplift and erosion associated with fold and thrust deformation of the Miocene Limestones (Hill & Gleadow 1989). This timing relationship suggests, that compressional deformation in the Mobile Belt occurred in the Late Miocene, at 105 Ma, and that the deformation migrated towards the undeformed foreland in the southwest in the Pliocene, at 5-2 Ma. The regional Late Miocene uplift and denudation in the Mobile Belt is also consistent with that postulated by Crowhurst et al (1996; 1997) for northwest PNG, although they considered the event to have occurred mainly from 8-5 Ma. If so, then the uplift and denudation may have been migrating from east to west as well as to the south into the Fold Belt. These timing relationships place significant constraints on tectonic models for the area, indicating that the major compressional pulse in PNG commenced in the northeast at -10 Ma and migrated to the southwest and west in the latest Miocene to Pliocene. This suggests that the initial arc-continent collision and associated shortening occurred in the Late Miocene around -10-12 Ma. This immediately followed intrusion and cooling of the Akuna Intrusive Complex at -17-14 Ma and the Bismarck Intrusive Complex at -12.5 Ma (Page 1976), indicating a linkage between the end of plutonism and the start of compressional deformation. The timing is consistent with the observation of Hamilton (1994) that in areas of subduction `the common regime in overriding plates is extensional and leading edges are crumpled only in collisions. This suggests that the Middle Miocene magmatism in northern New Guinea occurred during extension above a subducting slab and was terminated by Late Miocene arc collision and resultant compression commencing at -10-12 Ma. In general, these data indicate that the acme of denudation and cooling in the Mobile Belt was in the Late Miocene, with relatively little denudation there since. In contrast, Hill & Gleadow (1989) found that the peak of denudation in basement outcrops in the Fold Belt was in the Pliocene at -4 Ma. However, in this study some samples from the Mobile Belt yielded Pliocene ages or high

Jan 1, 1997

By Toru Yamasaki

A concept of plate-tectonic controls for the formation of seafloor massive sulfide (SMS) deposits in back-arc settings was established by Franklin et al. (2005). According to Franklin et al. (2005), a consequence of extension and rifting is subsidence, thinning of the crust, and the rise of hot, athenospheric mantle into the base of the crust. Underplating of the crust by mafic magmas results in low-pressure partial melting of the hydrated crust at a <15-km depth, and the generation of felsic anhydrous melts. The rapid ascent of hot felsic melts, along with mantle-derived mafic melts, results in bimodal volcanism that characterizes rift and volcanogenic massive sulfide deposits (VMS) environments. The rapid and focused advection of the magmatic heat within the rift to the near-surface environment which are required to sustain vigorous long-lived VMS hydrothermal systems. Faults within rift environments may also allow seawater to penetrate into subvolcanic intrusions and mix with magmatically generated metalliferous fluid or allow a direct magmatic contribution from shallow crustal level (3–12 km) magma chambers (Franklin et al., 2005, and references therein). In addition, the caldera-forming processes are favorable for the formation of VMS deposits and the focused high heat flow and cross- stratal structural permeability that is restricted in time and space to caldera development provides an explanation for the clustering of VMS deposits and their restriction to specific time-stratigraphic intervals and structures in the evolution of submarine central volcanic complexes (Franklin et al., 2005, and references therein). The concept is persuasive, although it is based on a series of logically constructed reviews mainly focused on ancient on-land deposits.

Jan 1, 2018

Low-grade, porphyry copper type mineralization at the Moonmera prospect is related to the intrusion of a granodiorite porphyry mass into the Upper Permian "Gracemere granodiorite". Significant copper mineraliza- tion appears to be associated with the alteration assemblage quartz-sericite- kaolinite. The ore shell is surrounded by a zone where montmorillonite and kaolinite are in greater abundance and this assemblage is over- lapped, mainly at depth, by potassium feldspar alteration. Secondary biotite is abundant throughout the mineralized zone. Preliminary sulphur isotope results on the sulphide mineralization are compatible with a magmatic origin for the sulphur.

Jan 1, 1974

By Alonso Marchena, William Martínez

El estudio que se ve reflejado en el presente artículo tuvo como objetivo mantener actualizado el mapa metalogenético del Perú y desarrollar conceptos sobre el origen de los yacimientos minerales, basados en datos geocronométricos, geoquímicos, isotópicos, estratigráficos y estructurales, en la Cordillera Occidental entre Ica y Tacna. La zona de investigación comprende las franjas metalogenéticas IV, V, VIII, IX y X. Se destaca el valor de herramientas tales como la litogeoquímica en la discriminación de pórfidos de Cu (Mo-Au) y se muestra la efectividad de nuevos parámetros de elementos traza en la discriminación y reconocimiento de magmatismo fértil vinculado a pórfidos en el sur del Perú.

Oct 30, 2020

By Luis Ayala, Francisco Solano

Entre Huachón y Corralcancha (Cordillera Oriental) se ha identificado un corredor estructural NO-SE (Chaska-Rumichaca) ubicado a ~30km al este de Cerro de Pasco. Cuyos límites son fallas regionales que determinan un bloque paleozoico del Complejo Metamórfico del Marañón (CMM). El límite occidental (Falla Rumichaca) corresponde a una falla inversa de vergencia SO que aflora dentro del CMM; mientras que el límite oriental (Falla Chaska) es una zona de cizalla compresional de vergencia NE que coloca al CMM sobre los Grupos Mitu (Pérmico superior-Triásico inferior) y Pucará (Triásico superior-Jurásico inferior) replegados. Este límite exhibe un flexionamiento de NO-SE a N-S que está asociado a fallas subordinadas de cinemática compresional, extensional y de desgarre.

May 1, 2008

By R Ratlou

Increased contamination due to sand in spiral feed has had a negative effect on the efficiency of spiral concentrators at Navigation Plant. The no. 1 seam at Kromdraai opencast, which was previously mined by underground bord and pillar methods, is now susceptible to spontaneous combustion because of air ingress into the old workings which are exposed in the opencast high wall. This posed a risk in the loss of reserves to burnt coal. As solutions, buffer blasting of the preceding cut to collapse bords and soft overburden dressing of un-collapsed bords were implemented to prevent air entering the workings. The latter remedy resulted in increased contamination due to addition of sand in Run of Mine. After evaluating alternatives, a low capital option was selected. The 110t/hr Teetered Bed Separator (TBS) has been installed, primarily to desand and upgrade the feed to the spiral concentrators. The unit indicated an upgrade with a yield increase of 0.4% during test work and is currently showing an overall plant yield increase of 0.97%.

Jan 1, 2006

By R. Drummond

The fourth Teetered Bed Separator (TBS) has just been installed in Australia, and trials have been run in many sites. There is a growing recognition of the potential advantages of using TBS technology to treat coal in the ?3+0.25 mm size range, at cut points below 1.60. From these activities, there has been a substantial growth in knowledge with respect to application engineering and operational functions. The paper briefly describes the installations, including flowsheets, and so provides a background to the potential deployment of TBS technology. There are a large number of potential applications for TBS technology, including treatment of fine ROM coal in new plants, or in upgrade situations for re-processing of spiral product, or scavenging coal from coarse tailings. As well, cost effective capacity upgrades are possible by using TBS units for treating the sands size fraction. Issues arising from Australian TBS installations and application engineering are also discussed.

Jan 1, 2002

By A. L. O’Neil, J. A. Wineland, A. B. Arnold

Movement of water through the Tehachapi Mountains was one of the most challenging parts of the planning, design, and construction of the California Aqueduct. The California Aqueduct is the main artery of the California State Water Project, which will move water 444 miles from the Sacramento-San Joaquin Delta into the arid and semiarid, densely populated parts of Southern California. The $2,000,000,000 project, designed and constructed by the California State Dept. of Water Resources, was started in 1957 at the Oroville Dam site and is now well past the halfway mark in construction. Water is now being delivered from the California Aqueduct to portions of the San Joaquin Valley. The California Aqueduct is scheduled for completion in 1972. Tunnels on the Tehachapi Crossing are often overshadowed in engineering descriptions of the Crossing by the tremendous importance and engineering significance of the Tehachapi pumping plant which will pump water through the tunnel system. For purposes of this paper, it will suffice to say that the plant is designed to lift 4100 cu ft of water per sec up approximately 2000 ft, making this the highest pumplift in the United States and one of the largest in the world. Water will be moved from the pumping plant through twin tunnels called the Tehachapi Discharge Lines to the top of the lift. From here, water will flow through four additional tunnels which are all linked by short connecting structures (Fig. 1). The tunnels are referred to as Tunnels 1, 2, 3, and Carley V. Porter Tunnel. HISTORY Selection of the final route of the Tehachapi Crossing was the result of comprehensive investigations beginning in 195 1. Numerous tunnel

Jan 1, 1970

By Thomas Pallua, William C. Gates

"Two major railroad companies have identified several segments along the railroad corridor betweenTehachapi and Bakersfield, Kern County in California that require construction of a second track to improve operations in this area. The total project proposes an upgrade of five segments along the Tehachapi-Bakersfield route. The authors focused on two segments: Walong to Marcel and Cliff Siding Extension. The second track project comprised design of a through-cut adjacent to an existing tunnel and up to 120-feet-high (36m) side-hill cuts (both in granitic rock). The authors characterized the geologic ground conditions and ground behavior, including rock mass quality and strength using a combination of rock core drilling and rock slope mapping. The rock mass is generally characterized as granitic tonalite with strong core stones surrounded by a matrix of decomposed granite (DG)."

Jan 1, 2017

By M. S. Davis

The Tek Process can produce masonry products such as bricks, roof or wall tiles, and block from virtually any inorganic waste. In the process the aggregate raw materials, portland cement, water and common chemicals are first mixed together; then mechanically subjected to several thousand pound pressure per square inch. This causes a novel chemical reaction between the cement, chemicals and water; producing the "patented" Tek adhesive binder which holds the aggregate together in a stone-like mix. Simultaneously, the desired product shape is formed. The building modules can have strengths of 8000 p.s.i. (pounds per square inch) with completely sound aggregates utilizing air curing for a period of 28 days. With most aggregates, 3000 p.s.i. is achieved within 24 hours. Eventual strengths usually exceed 5000 p.s.i. with almost any raw material. Water absorption ranges from 5-7.5 percent. Both absorption and strength figures are superior to the most rigid of any and all A.S.T.M. specifications for the highest quality bricks. In most locations, the product (when brick shaped is called Tekbrik) can be produced significantly more economically than can comparable grades of clay or other bricks, be- cause almost any inorganic waste materials or pollutant can be used as a raw material. The process results in a lower manufacturing cost as compared to clay bricks; fuel cost to operate a clay kiln represents a substantial portion of the total cost. Capital expenditure for a Tek plant also is lower due to the large investment in clay kilns. Transportation savings also are important, clay brick factories must be very large because the kilns are uneconomical unless they are large. Most bricks are manufactured at the sites of clay deposits in relatively uninhabited areas. The cost of transportation to the job site represents a considerable percentage of the selling price.

Jan 1, 1974

By Stephen C. Tadolini, Minova USA Inc., Peter S. Mills, David R. Burkhard

"Fiber-reinforced spayed concrete has been used for several years in civil and tunneling operations. Research conducted to reduce cure times and increase compressive and flexural strengths resulted in the development of Tekcrete Fast®, a cementitious product capable of obtaining 41 MPa (6,000 psi) compressive strength and 8 MPa (1,200 psi) flexural strength in only 3 hours and reaching 7 day strengths of 62 MPa and 11.7 MPa (9,000 and 1,700 psi), respectively. A single bag product that uses conventional shotcrete and gunite application systems make it a natural crossover product for mining applications. The discovery of incredible adhesion properties and high resistance to chloride permeability helps ensure long-term stability and increases the ease of application. Project results from Disaster City® in Texas and the application for rehabilitating a coal mine belt entry are presented. The case study illustrates the effectiveness of the product in stabilizing a coal mine beltway and adjacent cross-cuts that were subjected to progressive sloughage due to humidity and cyclical loading. INTRODUCTION Original research produced a shotcrete formulation that extends beyond stabilization and can be used to restore the structural integrity of damaged infrastructure. The primary challenge was to develop a shotcrete or gunite that had structural strength within a few minutes to prevent parasitic loading, allowing ingress into damaged structures minutes after applying the mix formulation. This also applies to mining conditions where rapid support of progressive failures can minimize failure. An additional benefit was discovering that the product had extremely high adhesion properties in addition to high flexural strengths. The approach to product design was the development of “single bag” dry mixes that are entirely self-contained, can be rapidly transported anywhere in the field or underground, and can be deployed using simple equipment. Dry mix eliminates issues relevant to high shear water mixing because water is added in the form of a mist at the point of delivery; thus a low water-to-cement ratio can be achieved. However, since there is no onsite powder mixing, the product must have a high degree of inherent homogeneity. Minova offers a commercial version of this material, Tekcrete Fast®, a product that has been successfully deployed in the mining industry and is currently being used in civil, construction, and tunneling operations. The material can rapidly stabilize lose ground in metal, nonmetal, and coal mines. This paper described the technology development, product testing results, and applications and describes a case study to stabilize a coal mine beltway."

Jan 1, 2017